The relation between redundancy and reliability, which is treated in Chap. 11, is discussed here only on a large scale The minimum addition in providing a dual or backup computer control system is adding another central processor, further duplication of equipment then depends on plant-design concepts, such as whether or not the reactor will be operable if the computer fails Also to be considered is duplication of critical functions by indepen­dent hardware. Analog and manual backup are examples 1 5

Table 8.2 shows some of the reasons for having or not having redundant computers The use of a nonredundant system is usually justified by the requirement that the reactor and processes be capable of at least steady-state operation if the computer tails This implies either exten­sive analog backup control or a plant small enough to be
influenced plant designers to allow shutdown in case of total control-system failure if redundancy is used 1 6

Restating the above if a high plant factor is important, then frequent shutdown cannot be tolerated and a redundant control system is required. This is the pre­dominant reason for dual computers A second reason, especially applicable to prototype facilities, is the impor­tance of maintaining continuity of plant operating data, a criterion that applies to pure data-acquisition equipment as well as control systems. A third justification is that a standby computer can be used for off-line program prepara­tion and data processing but can be automatically inter­rupted when the unit is called into service to replace the operating computer

It has become common to design nuclear power stations with two complete reactor—generator units operating in­dependently At first sight it seems that reliable computer control could be effected by placing a control system on each reactor unit using the computers as backup for each other, at least for the essential control functions Although this configuration has been given much consideration, few, if any, such systems have been built Both computers would have to be larger, peripheral switching to one or the other would be difficult, and developing the complex switching programs would be very costly. The result is that dual plants usually have three computers, one as standby for an operating system on each reactor unit.1 7

The basic justifications for the triple control system are the same as for redundancy in general the importance of reliability, as it affects plant factor, and the convenience of having a standby for off-line programming

The final objective of redundancy is to improve plant availability or, in project terms, to ensure that the system

Table 8.3—Cost-Comparison Chart Item Number required Cost, $ Analog System Panels 20,000 Meters 500 10,000 Recorders 12 (multipoint) 50,000 Annunciators 4000 (points) 240,000 Control hardware* 260,000 Data logger 4000 (points) 420,000 Spare parts 100,000 Total $1,100,000

Computer System
Central processors	2	150,000
Process input/output	4000 (points)	450,000
Mass storage	Drums, disk, and magnetic tapes	125,000
Operator input/output	Printers, typers, and consoles	75,000
Displays	Cathode-ray tubes and interfaces	100,000
Spare parts		25,000
Programming		350,000
	Total	$1,275,000

*Only for those functions which the digital system would perform.

will permit attaining the target plant factor The immediate objective is to make the control system more reliable However, a precise estimate of the reliability of a redundant computer system cannot be made because the reliabilities of the constituent parts—processor, peripherals, interfaces, and displays—are not precisely known. So it is not surprising that past and present justifications for replicating components are commonly based on judgment and infer­ence from statistically inadequate data on past operating experience. This state of affairs will prevail until reactor power plants with computer control are commonplace, at which time the need for stringent justification will be far less.

Two principal types of lead—acid batteries are in use today: Plante and Faure. Plante invented the lead—acid battery about 100 years ago using positive and negative plates of pure-lead sheets. Today batteries that have pure lead in their positive plates are called Plante types. The original Plante battery was expensive because the lead peroxide, which is the active material of the positive plate, was extremely difficult to form on the surface of the positive plate. Some time later, Faure invented an eco­nomical method of pasting lead peroxide on the positive plates and lead oxide on the negative plates. This is the type of construction used today.

Faure batteries can be either lead—antimony or lead — calcium alloy plate grid types. The names are derived from the hardening alloy material used in the manufacture of the plate grids. Of the many types of batteries available, the lead—antimony and lead—calcium Faure types are the most common in noninterruptible power supplies. A lead — calcium battery costs up to 15% more than a lead — antimony battery; however, the lead—calcium battery offers several advantages over the lead—antimony battery. The lead—calcium battery requires much less water replace­ment and therefore generates a proportionately smaller amount of hydrogen gas during the recharge cycle. The floating voltage is less critical, 2.17 to 2.25 volts per cell (compared to 2.15 to 2.17 volts per cell for the lead — antimony battery). If the lead—calcium batteries are float — charged between 2.20 and 2.25 volts per cell, they are reported to never require an equalizing charge. These advantages must be balanced against the higher initial cost of the lead—calcium battery since satisfactory operation for equal lifetimes can be expected from both types of batteries when properly maintained.

The current produced by a lead—acid battery results from the chemical reaction of dilute sulfuric acid on the active materials in the plates. Lead dioxide reacts with the sulfuric acid at the anode to produce a positive charge. At

’The maximum flux in a transformer is inversely proportional to the form factor (root mean square/average) for the input voltage. Since the form factors are 1.00 and 1.11 for square-wave and sinusoidal inputs (of the same frequency), respectively, there is an 11% additional swing in flux for the square-wave input. In view of the fact that this increase would increase the total core loss, it could lead to exceeding the rated temperature rise within the transformer at full load.

the cathode, metallic lead reacts with the acid to produce a negative charge. During the discharge process, sulfuric acid is consumed and replaced by a corresponding amount of water. During charging the process is reversed, acid being formed at the plates with a corresponding consumption of water and generation of oxygen and hydrogen gas.

As the discharge of a lead—acid battery progresses, the water formed is absorbed into the electrolyte, resulting in a reduction of the specific gravity of the acid. The battery open-circuit voltage depends on the concentration of the acid in contact with the active plate materials. The-voltage available for useful work is the voltage across the battery terminals during discharge. This latter voltage is equal to the sum of the internal cell voltages minus the drop due to the internal resistance of cells. The reduction of acid concentration as the cell discharges is accompanied by an increase in internal resistance; the increase is gradual at first and then rapid as the cell approaches full discharge. The internal resistance may increase by as much as a factor of 2 to 3 on approaching full discharge. The internal resistance of a fully charged battery is so small that it has little effect on the terminal voltage except when high discharge rates are encountered. During discharge lead sulfate accumulates on the plates. Lead sulfate is a nonconductor and has a tendency to block the pores of the plates, thereby impeding the chemical reaction. Sulfate is a contributing factor in the reduction of the terminal voltage during discharge.

When the battery is discharged at low rates, the formation of water and lead sulfate proceeds slowly, allowing the acid in the electrolyte to be readily absorbed into the pores of the plates and resulting in a gradual decrease of the terminal voltage. When the battery is discharged at a very high rate, the depletion of acid at the plates takes place so rapidly that the rate of acid replace­ment cannot keep pace, which causes a greater reduction in terminal voltage. The increased depletion of acid at the plates on high discharge is the primary reason that batteries have a lower ampere-hour capacity at high discharge current rates.

The capacity of the lead—acid battery is reduced as the ambient temperature decreases. The amount of reduction also depends on the rate of discharge and cell design. The major reasons for the reduction in capacity with decreasing temperature are the increased electrolyte viscosity, which impedes the diffusion of the acid at the plates, and the higher internal cell resistance caused by increased resistance of the electrolyte. The common practice is to refer to the capacity of a battery at reduced temperatures as a percentage of its capacity at 77 F.

Batteries are rated on the basis of ampere-hours, which means the amperes that the battery will deliver for a given time at a specified temperature to reach a specified “final” voltage. The standard battery terminal voltages commonly used are 24, 48, 120, and 240 volts. These correspond to 12, 24, 60, and 120 cells, respectively, at a nominal 2 volts per cell. Faure batteries are float-charged at a cell voltage ranging from 2.15 to 2.25 volts, depending on the type of cell. Determining the size or ampere-hour capacity of a battery involves a detailed procedure that is beyond the scope of this test. (Details of the methods are given in the bibliography at the end of this chapter ) Sizing of the bat­tery can be done by the design engineer, who is aware of the battery limitations, or by the manufacturer or supplier of the nonmterruptible supply package In general, the battery must have sufficient ampere-hour capacity to carry momentary loads plus continuous or basic loads for a specified length of time before reaching its final voltage, commonly referenced at 1.75 volts per cell

A lead—acid battery must receive the correct charge to give optimum performance and life. It is difficult and impractical to obtain this precisely on every charge or under floating operation. Lead—acid batteries do not need a full charge on every recharge to obtain satisfactory opera­tion. For long life, however, they must be brought to the fully charged condition periodically, the period depending on the degree and frequency of discharge On daily or frequent recharges, it is common practice to charge slightly short of a fully charged condition, a complete charge must be made every 1 to 3 months This complete charge is commonly referred to as an “equalizing charge ” Most modern battery-charging equipment is designed to effect a periodic equalizing charge.

The equalizing charge is intended to be sufficient to equalize any minor differences among the cells and should be continued until each cell of the battery reaches maximum voltage and specific gravity. To achieve this state requires manual attention and is, therefore, impractical However, the same effect is obtained by giving the entire battery an additional amount of charge for a limited period, which is not harmful to the battery. Most charging is controlled by an automatic timing switch incorporated in the charging equipment The most practical means of giving an equalizing charge is to set the time switch for an additional period of time For batteries in normal full­floating service, which is the most common service in standby power systems, a common practice is to raise the floating voltage above its normal value by about 5 to 10% for a period of 8 to 24 hr, depending on the type of battery and application. It is important to ensure that any nonmterruptible loads on the battery during the equalizing charge are rated for operation at the higher voltage levels

The efficiency of a battery may be expressed as ampere-hour efficiency, voltage efficiency, or watt-hour efficiency. Ampere-hour efficiency is the ratio of the number of ampere-hours a battery yields on discharge to the number of ampere-hours required to fully recharge the battery. A typical lead—antimony battery requires a re­charge in ampere-hours about 10% greater than the previous discharge, and the ampere-hour efficiency is 91%. Voltage efficiency is similarly defined as the ratio of discharge voltage to charge voltage. For the same typical lead — antimony battery, the average voltage on charge is approxi­mately 17% higher than on discharge, the voltage efficiency is 85%. The product of ampere-hour and voltage efficiencies gives a watt-hour, or total, efficiency. For the lead- antimony battery, the watt-hour efficiency is 0.91 X 0.85, or 77% This is a representative value for such batteries. (The watt-hour efficiency is slightly higher for a typical lead—calcium battery.)

The Faure battery is the most reliable single component used in nonmterruptible power systems today. Properly designed, battery-supported systems afford the optimum in overall reliability.

The Dresden plant has a boiling-water reactor system using a dual steam cycle and forced circulation. Figures 7.17 and 7.18 depict two views of the reactor vessel. Eighty cruciform-shaped control rods are interspersed through the array of fuel assemblies. Figure 7.19 shows how the control rods are arranged in the core.

The control rods were originally made of 2% boron- steel alloy but were replaced by stainless-steel sheet packed

Table 7.3—Detailed Description of San Onofre Control-Rod
Actuation [18]

Control-Rod Withdrawal: Sequence of Operations

1. Movable gripper coil—On.

2. Stationary gripper coil—Off.

3. Lift coil—On. The У — in. gap between the lift armature and the lift magnet pole closes, and the drive rod rises one step length.

4. Stationary gripper coil—On. The stationary gripper armature rises and closes the gap below the stationary gripper magnet pole. The three links, pinned to the stationary gripper armature, swing the stationary gripper latches into a drive-shaft groove. The latches contact the shaft and lift it Уз2 in. In this manner, the load is transferred from the movable to the stationary gripper latches.

5. Movable gripper coil—Off. The movable gripper armature separates from the lift armature under the force of three springs and gravity. Three links, pinned to the movable gripper armature, swing the three movable gripper latches out of the groove.

6. Lift coil—Off. The gap between the lift armature and lift magnet pole opens. The movable gripper latches drop in. to a position adjacent to the next groove.

7. Movable gripper coil—On. The movable gripper armature rises and swings the movable gripper latches into the drive-shaft groove.

8. Stationary gripper coil—Off. The stationary gripper latches, and the armature moves downward by gravity until the load of the drive shaft is transferred to the movable gripper latches. It then swings out of the shaft groove.

The sequence described above, where the control rod moves У in.

for each cycle, is termed “one step” or “one cycle.” The sequence

is repeated at a rate of up to 40 steps per minute. The control rod

is thus withdrawn at a rate of up to 15 in. per minute.

Control-Rod Insertion: Sequence of Operations

1. Stationary gripper coil—On.

2. Movable gripper coil—Off.

3. Lift coil—On. The movable gripper latches are raised to a position adjacent to a shaft groove.

4. Movable gripper coil—On. The movable gripper armature rises and swings the movable gripper latches into a groove.

5. Stationary gripper coil—Off. The stationary gripper armature moves downward and swings the stationary gripper latches out of the groove.

6. Lift coil—Off. Gravity separates the lift armature from the lift magnet pole, and the control rod drops down in.

Fig. 7.17—Longitudinal section of the Dresden reactor showing control-rod drives mounted below the reactor. (From Andrew W. Kramer, Boiling Water Reactors, p. 461, Addison—Wesley Publishing Company, Inc., Reading, Mass., 1959.)

the reactor in the “up” position. Reactivity is increased by lowering the control rod below the core. The control-rod

drive mechanism is basically a hydraulic cylinder. Normal controlled movement of the rod is attained by applying reactor feedwater regulated at 200 psia above reactor pressure to either the top or bottom surface of the piston rod and simultaneously connecting the opposite side to a vent tank held at 30 psia above reactor pressure. This movement, however, cannot be effected until the locking ball located in a slot between the control-rod piston and the cylinder wall is released by the unlocking piston (Fig. 7.20). For rod “up” motion (direction toward decreasing reac­tivity) pressure is applied on the bottom of the piston rod. The control-rod piston, secured by the ball to the spring — loaded locking piston, moves upward a small but sufficient distance against the spring to release the ball into the annulus in the unlocking piston and free the rod. The rod continues to move upward as long as pressure is kept applied to the “up” inlet port. When the inlet pressure is shut off, reactor pressure is applied through the shuttle valve, and upward movement continues until the next notch in the piston reaches the ball. At this point, the spring loading of the locking piston is enough to lock both pistons together and prevent further movement.

For “down” motion, the high pressure is applied to the “down” inlet port and the “up” inlet port is switched to the vent tank. In this condition, the high pressure is applied to the top surfaces of both the rod piston and the unlocking piston. The unlocking piston moves down against a spring load and exposes an annulus that frees the locking ball, allowing the main rod piston to be moved. If the down pressure is maintained, rod down movement continues. If the pressure is applied only momentarily, the ball is freed long enough to allow the piston to move to the next slot where it again engages the locking piston and stops.

There are 12 slots along the 8.5-ft travel of the control rod, and rod movement in 8-in. steps can be obtained. The maximum rate of reactivity insertion from this control rod is 1.3 X 1СГ4 6k/sec. The interlocking circuits allow move­ment of only one rod at a time.

For scramming, a 1400-psi accumulator tank is supplied for every three drives. For each drive two solenoid valves provide pressure to the “up” inlet port and open the “down” inlet port to a dump tank. The rod movement for scram is completed in 2.5 sec.

Rod position is indicated by a series of magnetically operated switches located inside an inner cylinder along the drive stroke. A magnet built into the rod piston actuates the switches as it passes them, and corresponding indicating lights on the control panel show the rod position.

The effect of scram-system failure is minimized by the use of independent systems for every three rods. If a large-scale failure occurs, however, a chemical poison — injection system containing sodium pentaborate at a pres­sure much higher than that of the reactor is actuated.

7- 4.4 Gas-Cooled Reactors

Gas-cooled reactors can be considered as being either low-temperature or high-temperature gas-cooled reactors.

The low-temperature gas-cooled reactors are typified by the natural-uranium graphite-moderated C02 — cooled units in the United Kingdom and similar installations in Italy, France, and Japan. These reactors are very large structures owing to the low excess reactivity available from natural — uranium fuel. For example, 40- to 70-ft diameter and 40-ft height are typical. The number of control rods is corre­spondingly large, 100 or more. The control rods (usually boron steel) are generally mounted and operated vertically. They are suspended by steel cables wound around a drum which is driven by a low-speed motor equipped with induction braking. A typical control-rod drive mechanism is shown in Fig. 7.21.

The control problems in low-temperature gas-cooled reactors arise chiefly from spatial variations in fission — product (especially 135Xe) poisoning. To cope with these problems, for example, the Hunterston reactor in Scotland is divided into one central zone and eight radial zones, with the control rods distributed throughout. The central zone

HEAD LIFTING LUG (4 REQ-AZIMUTH 45*- l35*-225*- 315*)

HEAD STUDS (56 REQ)

CHANNEL SUPPORT BRACE — 14 REQ)

PRESSURE DIFFERENTIAL TUBE HEADER AND OUTLET

Fig. 7.20—Control-rod drive mechanism, Dresden Nuclear Power Plant.

GRID (36 RODS) Fig. 7.19—Dresden reactor fuel-element and control-rod array. Fuel elements are 36-rod assemblies of U02 contained in Zircaloy-2 tubes. Cruciform control rods fit in spaces between the elements. (From Andrew W. Kramer, Boiling Water Reactors, p. 464, Addison—Wesley Publishing Com­pany, Inc., Reading, Mass., 1958.)

has the largest number of rods per unit cross section area The rods in each zone are grouped for control purposes and each rod can be independently operated.

The normal rate of addition of reactivity is very low in the low-temperature gas-cooled reactors. In the Berkeley (England) reactor, for instance, the rate is 2 X l(f6 5k/sec Start-up from a cold shutdown condition to critical takes 6 or 7 hr, to increase from critical to full power takes 11 hr because of the negative temperature coefficient.

High-temperature gas-cooled reactors (HTGR’s) use enriched-uramum fuel and are much smaller in size than the low-temperature reactors. Graphite is used as moderator A variety of coolant gases may be used, including N2, C02, H2, He, and air In the United States, helium is used, elsewhere, carbon dioxide is the favored coolant for gas-cooled power reactors

The Peach Bottom HTGR and the Fort St Vrain HTGR, two U. S nuclear power stations, are described in some detail in Vol. 2, Chap. 18. In Chap. 18, Sec. 18-6, there is a discussion of their control-rod drive and position — indicating systems The brief description of the Peach Bottom control-rod drive mechanism presented here over­laps the Chap. 18 material to some extent. However, the emphasis is different. Specifically Unit 1 of the Peach Bottom Power Station in Pennsylvania is considered here The core, located near the bottom of a 25-ft-high cylindri­cal pressure vessel, is approximately 9 ft in diameter and 7.5 ft high There are 36 control rods, each worth 0.007 6k (average), mounted below the reactor where the drive mechanisms are in a mild environment (^200°F and ~10 R/hr gamma flux) The location provides for easy access to maintain the drives and leaves the top of the pressure vessel free for fuel-handling operations. The control rods are stainless-steel tubes containing boron carbide.

The basic drive mechanism (Fig. 7.22) is an axial piston-type hydraulic motor that turns a ball screw and produces linear motion of a ball-nut assembly The ball-nut moves a push rod, which, in turn, raises or lowers the control rod Each control-rod port (extension of the pressure vessel) contains the entire drive mechanism includ­ing the hydraulic motor, regulating and scram valves, position transmitters, rotary-to-linear motion ball-nut screw device, scram-energy accumulator, and scram-action snubber

Hydraulic turbine oil is used for the motor and is supplied to the drive from two header connections One is a low-pressure supply that produces the normal operating speed of the control rod. The high-pressure line maintains the fluid level in a scram accumulator, pressurized by helium, which drives the rod at the scram speed of 10 ft/sec. A return header is supplied for the effluent from the motor The regulating and scram speeds of the motor are estab­lished by two sets of solenoid valves. One set, the regulating valves, admit low-pressure hydraulic oil for rotating the motor in either direction. The other set, scram valves, apply high-pressure oil to the motor for one direction of rotation only, namely, that for driving the rod upward into the core.

Total rod movement is 7 ft. The regulating or control speed is 0.06 ft/sec or 0.72 in./sec, corresponding to a rate of change of reactivity of 1.1 X 10-4 5k/sec (maximum) Except for rod-removal operations, the drive is never detached from the rod. Monitoring of the coupling between the drive and the rod depends on an electrical circuit between the two, which, if broken, trips an annunciator at the operator’s console. Downward motion of the rod increases core reactivity, and scram motion is upward. Control of rod direction is by manual activation of solenoid valves through remote switches or from an automatic “on-off” control circuit.

A clutch-brake on the hydraulic-motor shaft prevents downward drift of the rod when no hydraulic pressure is being applied to the motor. This is accomplished by means of a friction brake and an over-running clutch that allows completely free rotation of the shaft to produce rod motion upward (decreasing reactivity) but applies a reverse torque at 1.75 to 2.5 times that produced by the deadweight of the rod and attached drive parts acting vertically. The operation of the hydraulic motor, however, easily overcomes this friction when rod-down motion is desired. A mechanical latch holds the rod in the “up” (full-in) position after insertion. The latch has to be actuated when the rod is withdrawn down past the latch Mechanically, the latch cannot be withdrawn if the rod weight is on the latch. Safety requires that no more than three rods at one time be in a position intermediate between latched in and full out.

There are two independent emergency shutdown sys­tems. One is a group of 19 electrically driven emergency shutdown rods. These rods are operated by conventional Acme thread screw-nut mechanisms driven by simple and rugged d-c motors. Batteries, located in an extension of the rod port housing, supply power to drive the motors in the scram direction External d-c supplies are used to provide withdrawal power to these drives. Operation of these rods is by operator manual control only. They are used only in the event that normal scram operation fails. Complete rod insertion is attained in 24 sec, and the design provides very large torques that can overcome a resistive force as high as 10,000 lb, in which case insertion takes 1 min. Such operation was provided for the remote possibility that reactor damage (warping or debris) could restrict the normal movement of the rods The other emergency shutdown system, located in the top section of the guide tubes for each of the control and emergency shutdown rods, is a set of 5 5 gravity-drop neutron absorbers that are thermally released by abnormally high core temperature. This system is intended to operate in the event the other rod systems fail to act

Rod-position indication is provided by four selsyn receivers and by limit lights Each control-rod drive mechanism contains a selsyn transmitter geared to 170° rotation for full rod travel. Each position indicator has a graphical display (column type,~5V2-m scale corresponding to 0 to 84-in. rod travel, position accuracy ±2%) and a

CONTROL ROD — GUIDE SLEEVE

f a I

BALL SPLINE

-CONTROL ROD

, V : : ■

GRID PLATE

ROTARY FACE-TYPE DIFFERENTIAL PRESSURE SEAL-~-Ulj^

COOLANT FLOW

ROD BACKSTOPPING DEVICE-

HELIUM PURGE

PRESSURE VESSEL

POSITION AND CONTROL TRANSDUCERS’

-SCRAM DECELERATION VALVE -SCRAM EMERGENCY SNUBBER

HYDRAULIC MOTOR AXIAL PISTON TYPE.

BIOLOGICAL SHIELD

——— FLUID LEAKAGE DETECTOR

PRESSURE

RETURN

‘SOLID PUSH ROD

Fig. 7.22—Control-rod drive for Peach Bottom gas-cooled reactor.

digital display (three digit counter calibrated in inches, indication of rod position ±0 12 full scale, full-scale slewing time <6 sec)

When operating at power, the reactor is controlled by a group of three rods in the center region of the core The particular rods in the group are continuously monitored by the synchro position indicators at the reactor operator’s console The fourth indicator is switched to the individual rod being moved and thus serves as a check on the synchro-receiver normally on that particular rod. The remainder of the rods not being used for control are either full in or full out, as indicated by a green or red background light in the particular control-rod window on the operating console, the lights are operated by upper and lower limit switches In addition, a precision potentiometer is driven from each rod-drive gear train to provide for testing rod response and operation and for checking rod-position indication if a synchro-transmitter malfunctions

7- 4.5 Fast Reactors

The control systems for fast reactors (EBR-2 and Fermi) are described in Vol 2, Chap 17, Sec 17-2

REFERENCES

1 United States of Amenta Standards Institute, USA Standard Glossary of Terms m Nuclear Science and Technology USAS N1 1 1967, USA Standards Institute New York, 1967

2 M A Schultz, Control of Nuclear Reactors and Power Plants, 2nd ed, McGraw Hill Book Company, Inc, New York, 1961

3 W H Esselman and W H Hamilton, Position Control in Sealed Systems, in Proceedings of the 1953 Conference on Nuclear I nergy University of California Press, 195 3

BIBLIOGRAPHY

Argonne National Laboratory, The EBWR Experimental Boiling Water Reactor, in AFC Nuclear Technology Series, USAEC Report ANL 5607, May 1957

Freund, George A, Materials for Control Rod Drive Mechanisms Rowman and Littlefield, Inc, New York, 1963

Harrer, Joseph M, Nuclear Reactor Control Fngineermg, D Van Nostrand Company, Inc, Princeton, N J , 1963

Hutter, E., Fast Reactor Control Mechanisms, AEC, Washington, D C,1964

International Atomic Energy Agency, Directory of Nuclear Reac tors, Vol I VI, International Atomic Energy Agency, Vienna, Austria

Lipinski, W C, J M Harrer, and R L Ramp, in Reactor Handbook Vol IV, Engineering, Chap 8, Interscience Pub­lishers, a division of John Wiley & Sons, Inc, New York, 1964

Loftness, Robert L, Nuclear Power Plants Design, Operating Fxpenence and hconomics D Van Nostrand Company, Inc, Princeton, N J, 1964

Nuclear Power pp 282 286, November 1956

Nuclear Power p 5 3 ff, May 1962

Nuclear Power pp 90 97, April 1962

Weaver, Lynn E, Systems Analysis of Nuclear Reactor Dynamics, Rowman & Littlefield, Inc, New York, 1963

(a) Temperature Control Temperature control of in strumentation systems is usually not given sufficient atten tion For example, although the overall average temperature of all components may not be excessive, many “hot spots” can develop through improper attention to cooling require ments Even though such hot spots may not cause immediate failure, the) eventually show up in system failures and poor mean time before failure (MTBF), with resulting high maintenance costs Although temperature considerations are basically a design function, no designer’s product can function effectively if operated in an environ ment m which it was never intended to operate For this reason those in charge of the installation must make certain that all equipment is operated within the designed environ mental limits, whether thermal, vibrational, radiation, or any other

Since most instrumentation equipment is located m enclosed cabinets, proper ventilation must be provided to avoid convection cooling that may allow heat from a lower chassis in a cabinet to pile up in the top chassis, thereby effectively “baking” every component in the equipment Under these conditions some units that functioned well in a

HIGH- PRESS. GAGE

LOW- PRESS. GAGE

fed

{X}

FROM COMPRESSOR STORAGE TANK

INSTRUMENT SYSTEM

ISOLATION FILTERS VALVES

PRESSURE — ISOLATION REDUCING VALVES STATIONS

DRAIN COCK

txl

Fig. 10.12—Dual-filter regulator station For actual installation see Fig 10 4

as clearance for operational safety.

55°C test oven have been known to fail when operating in a “room-temperature” relay rack For this reason each chassis placed in a cabinet must be checked for power consump­tion before installation and provisions made for the total cooling load demanded per cabinet The type of equipment in the cabinet must also be considered, for example, a log amplifier requires closer temperature control than a rela

If temperature might be a problem (either high temper­ature for indoor installation or low temperature in winter at outdoor locations), provisions for correcting the problem should be made before the equipment is installed, not after Since the instruments in control rooms are usually a large source of heat, air may be drawn from the room through vents placed in the bottom of each cabinet and then drawn out of the top of the cabinet into the building’s central air-conditioning return. Additional cooling capacity ma be required in the air conditioning system at the time of plant construction to handle the load of the control room If proper size ducts are used from the cabinets to the air return, the airflow through the equipment and in the room will he silent, low speed, and unobtrusive If the air input to the room is filtered, the control room will stay clean as well as cool, providing a more pleasant and lower maintenance environment Each cabinet mav also be equipped with a thermometer so that the cabinet temperature can be monitored

During set up and testing of cabinet-mounted equip ment, temperature-sensitive materials, such as tempilac, may be placed in areas of high-component density and low airflow or on components that require critical temperature control to be effective If after 8 hr of operation the temperature sensitive materials indicate proper operating temperatures, the airflow should be turned off or blocked, and the effect of the ensuring temperature rise on the equipment operation should be noted If any significant changes occur, an alarm annunciator should be installed to signal and warn of loss of sy stem airflow

Other than the electronic package located m the control room, the most critical area regarding temperature regula tion is around the reactor itself Energy dissipated in the reactor shielding material produces heat which raises the temperature of any detectors or other sensors in close proximity to the core Those responsible for installations should be certain that the ambient temperatures of each sensor location do not exceed those recommended by the manufacturer and that any connecting cable is rated for the environment in which it must perform.

(b) Vibration Control. Every attempt should be made to mount instrumentation in vibration-free areas When it is necessary to plate instruments in high-у ibration positions, it is most important that neither components, portions of the case, nor wires of any kind resonate at any of the vibrational frequencies involved since metal fatigue will most certainly cause ultimate failure

The easiest cure for vibrational problems is to shock mount the equipment and fasten securely all wiring harnesses by using anti wicking tools on connector solder points Anti-wicking tools prevent solder from flowing within stranded wire to a point beyond which the insula­tion has been stripped from the wire Other approaches mav also be required, including silicone rubber encapsula tion of wires and connectors, special internal vibration dampening of equipment, etc For further information on vibration control, see Defense Department Wire Specifica­tion MIL-W-5088C 01 MIL W-9160D

(c) Selection of Insulation for Radiation Environment.

Wiring insulation exposed to environmental extremes of radiation should be carefully selected It would be desirable to select wire that could withstand radiation exposures for the life of the plant (about 40 у ears) Extensive irradiation research programs have been conducted and numerous tables have been compiled on radiation damage to wire conductors and insulating materials

This chaptei contains several tables on radiation effects on materials These tables are typical and may or may not agree with specific results obtained by other research organizations

There is no substitute for experience gained in oper ating nuclear plants It has been found that out-of-core detector wiring and some m-core yviring may be good for only 24 months or less Replacement of this wiring at refueling time is considered standard operating procedure

Tabic 10 1 shoyvs the radiation stability of plastic insulating materials Klein and Mannal concluded that only inorganic insulation materials could function yyithin the reactor primary shield since radimon dose rates up to 101 2 rads/hr are often experienced [21] I he same type of insulation will be required in the containment vessel of a fast breeder reactor, where levels are expected to reach 10s rads/hr Outside the primary shield but inside the containment vessel of a thermal reactor, the dose rates may range from 0 5 to 160 rads/hr, and temperatures up to 70°C may be expected

On the basis of the foregoing assumptions and a 40-y ear plant lifetime, wiring inside the containment yessel may be expected to absorb 5 X 107 rads under normal conditions, a power excursion or other nuclear accident may add another 4X 106 rads Auxiliary structures, eg, residual heat remoyal compartments, outside the containment yessel mav be expected to receive dose rates 1/100 that of objects yyithin the containment yessel, but, in the event of an accident, these areas must be able to yvithstand much higher ley els

The temporary effects of radiation on elastomer based cables include thermoluminescence, decrease in electrical resistance, and gas generation I ong term effects include cither embrittlement or softening of the insulation Present theories tend to support the view that the cumulatnc

Table 10 1—Radiation Stability of Plastics* Material Threshold dose for + 5% change, t 103 rads Polystyrene 40 Phenol formaldehyde (asbestos filler) + 40 Polyester (mineral filler)4* 4 Polyvinyl chloride ft; 1 Polyethylene^ 0 9 Urea formaldehyde $ 0 5 Monochlorotrifluoroethylene i; 0 2 Cellulose acetate^ 0 2 Phenol formaldehyde (unfilled);}: 0 1 Methyl methacrylate^ 0 01 Polyester (unfilled):). 0 01 Polytetrafluoroethylene (Teflon) 0 01 *Irom P M Klein and C Mannal The l ffects of High hnergy Gamma Radiation on Dielectric Solids, in All / transaction*. on Communications and l lectromcs Parti, Vol 74, p 723 January 1956 + Based on most sensitive property, usually tensile strength f Crosslinks t Scissions

radiation damage to a substance in or near a nuclear reactor depends on the rotal energt absorbed b the material and is not a function of the type of radiation Accordingh, neutron damage to cables can be determined by referring to the tables for gamma-radiation damage and adjusting the total dose to account for the neutron energy Tables 10 2 to 10 6 show degradation as a function of absorbed dose caused by gamma radiation on various parameters of a cable and for various types of cable insulations Ггшп these findings, Blodgett and I isher presented the data shown as Table 10 7. The table lists and rates matenals that may be used successfully in various nuclear environments

10- 3.4 Installation Symbols

The designers of nuclear power plants use different symbols on drawings for the installation of instrumentation and electrical systems Although there are some relevant electrical codes and standards, there still appears to be lack of uniformity throughout the industry

Table 10 8 lists symbols typical of those currently used in the nuclear industry.

After the program description and the equipment configuration have been developed, the control engineer has enough information to make a preliminary estimate of system cost He compares the conceptual computer system with a conventional analog layout designed to perform the same basic tasks, which shows whether or not the computer control system is economically acceptable The analog equipment will include panels, panel meters, data loggers, strip-chart recorders, alarm annunciators, and controllers Some controllers must be capable of three-mode, feed­forward, and cascade operation. The systems should have equivalent orders of reliability and redundancy.

In all likelihood the computer control hardware re­quired for a reactor power plant will have a lower cost estimate than the analog configuration but will have a higher estimate when the cost of computer programming is included (see Table 8 3) If so, the decision to use a computer system has to be justified on the basis of services beyond those which analog systems can provide The values of such advantages are difficult to assess, they depend on such things as future savings in plant operating cost, benefits in case of a plant accident of low probability, and capability of readily accommodating later plant modifica­tion. Examples of some advantages are

1. The computer can lessen the time and effort applied to system installation and checkout For instance, several hundred sensors and cables can be connected and tested all at once by using a short computer program to detect and print out faulty channels Such procedures substantially lower installation time and cost compared with the standard method of “ringing out" each signal path by hand

2. The control-room staff can possibly be reduced because of greater efficiency in data acquisition and display Considering the cost of an operator over the lifetime of the plant (diminished by the initial cost of training personnel in the capability, programming language, and structure of the computer-based system), this factor can tip the scales in favor of a computer system Large offsetting increases in other activities usually are not expected, for example, the number of maintenance person­nel should be abouf the same with either kind of hardware, although they will generally be more highly paid for maintaining computer hardware.

3. At some time during its life, the plant will undergo changes in components, operating mode, or power level. The cost of altering the instrument and control system to provide for such changes will vary greatly but will be less with a computer system The cost of adapting to plant modification is hard to forecast except when such action is planned from the beginning. The latter is illustrated by a full-scale prototype power plant that is currently under construction.1 8 At start up and during initial testing, the plant will run with saturated steam, later to be changed to superheated steam to produce full-design electric power. It is estimated that the changeover will be done in a few hours by loading new computer programs, m contrast to a many-month-long job of altering conventional analog equip­ment.

4 The ability to format and output both transitory and permanent data in report form is an asset These data include postincident data, fuel exposure and inventory, and management reports on plant operation.

5. Reactivity balance, control-rod calibration, reactivity coefficient, and other complex on-line calculations can materially aid in efforts to achieve optimum reactor operation.

After all factors such as the above are taken into account and given conservative cost values, the total is incorporated into the initial system cost for comparison against an analog configuration.

The reader is cautioned that the figures in Table 8.3 are composite and illustrative. The cost ratios of the separate items will differ greatly for the various types of reactors and different plant operating modes

The systems described in Secs. 9-5 6 and 9-5 7 use an eddy-current magnetic coupling in combination with a stored-energy flywheel to obtain limited sustained opera­tion (i. e., 10 sec to 2 min) after failure of the normal source of power. An eddy-current coupling consists of rotor and stator assemblies, quite similar in many aspects to the common squirrel-cage induction motor. The rotor assembly is an input shaft on which is mounted a field coil and pole pieces, the coil being energized from a d-c source through slip rings. The stator is simply a hollow soft-iron cylinder with the output shaft attached to one of the cylinder bases

The air gap between the rotor pole pieces and the inner surface of the stator is small. As a result, the magnetic field established by energizing the rotor coil is concentrated in the soft-iron cylinder As the energized rotor rotates within the iron cylinder, the magnetic flux of the rotor sweeps through the stator cylinder and induces eddy currents The eddy currents in the stator set up magnetic fields that interact with the rotor fields, and, as a result, torque is developed which tends to drag the stator along with the rotor. There must be relative motion between the rotor and stator to develop any torque If there is no relative motion, no eddy currents are produced and no torque is created. The amount of torque produced by the coupling is a function of the rotor field strength and the speed difference between rotor and stator The output torque (stator) increases with increased rotor excitation and also with increased slip.

The use of a rotating field coil and slip rings with brushes creates maintenance and reliability problems that can be eliminated by using a brushless stationary field coil In this type of eddy-current coupling, the excitation coil is rigidly mounted in a frame. The input shaft carries a smooth cylindrical drum designed so that there is a small air gap between the stationary field assembly and the drum The output shaft carries the rotor, which is fitted into the input shaft cylindrical drum and separated by a small air gap. The flux path is from the stationary field poles to the cylindrical drum on the input shaft to the rotor and then axially m the rotor back to the cylindrical drum and to the field poles. The flux actually traverses two air gaps, as opposed to only one when slip rings and brushes are used. The output torque is developed by the interaction of eddy-current-induced magnetic fields on the inner surface of the cylindrical drum with the main field concentrated in the rotor. The main field flux is prevented from being short-circuited m the cylindrical drum by a nonmagnetic strip that separates the two halves of the drum. The stationary field design has increased reliability and reduced maintenance. The efficiency is less than that of a brush and slip-ring coupling because the double air gap requires more excitation for equal output torque

As noted earlier, the eddy-current coupling is similar to a squirrel-cage induction motor. In an induction motor a rotating magnetic field is established in the air gap by means of a polyphase winding on the stator. In the eddy-current coupling of the rotating field type, a rotating field is established by mechanical rotation of the energized rotor assembly by a prime mover The soft-iron cylindrical rotor of the coupling is analogous to the squirrel-cage rotor bars of an induction motor. In addition to these similarities, the slip-torque characteristic of an eddy current coupling is similar to that of a squirrel-cage induction motor. The slip-torque characteristic of an eddy-current coupling can be modified in the same manner as that of an induction motor. Use of high-resistance material for the soft-iron cylinder affects the slip-torque curve of an eddy-current coupling in the same manner as the use of high-resistance rotor bars affects the slip-torque curve of a squirrel-cage motor.

Eddy-current couplings are noted for their low ef­ficiencies, especially for large differences between input and output shaft speeds. Whenever the output speed is different from the input speed, heat is generated. This loss, called slip loss, is essentially equal to the difference between input shaft power and output shaft power. Slip loss is the major source of heat in an eddy-current coupling, and the heat must be dissipated by cooling fluid or air. At rated torque and output speed, the slip loss of a typical eddy-current coupling will be about 2 to 4%. Considering other losses, such as friction, windage, magnetic drag, and excitation, the peak efficiency is about 92%. At reduced speeds the slip loss increases, and the efficiency becomes essentially equal to the ratio of output speed to input speed.

The application of an eddy-current coupling in a nonmterruptible power supply with a drive motor, stored — energy flywheel, and output generator requires a large difference between the input and output eddy-current coupling shaft speeds. This results m a large coupling slip loss and hence poor efficiency, this can be relieved by operating normally without energizing the eddy-current coupling, see Sec 9-5 7

If the poor efficiency experienced when operating with the coupling normally energized is discounted, extremely close speed control and hence output frequency control can be attained with an eddy-current-coupled system. Upon coast-down, after losing the prime mover input power, the eddy-current coupling, used in conjunction with a flywheel, is able to dissipate the flywheel stored energy at a finely controlled rate just sufficient to maintain a constant output shaft speed (thereby providing an acceptable generator output) for intervals as long as several minutes.

Garth Driver and Robert E. Mahan

8- 1 INTRODUCTION

The meaning of “automatic control” has changed over the years along with the advance of control technology, the change being mainly one of scope At one time describing a servomechanism, the term was broadened to include feed­back control of a single process parameter, now it usually denotes the untended operation of complex processes or entire plants The word “automation’ was coined to indicate the elimination of the actions and decisions of human operators, it will be applied in this chapter to the internal control of nuclear reactor facilities However, just as advances in automatic control were expansions of scope based on previous technology, we may expect that automa­tion will soon be taken to imply optimum operation under changing external influences, such as product markets and raw materials costs

The instrument engineer has recently been given the chance to begin applying several decades of theory to the control of real industrial processes 1 The means were provided by those digital computer manufacturers who designed or modified their equipment for on-line data handling and control and who developed the beginnings of process program systems Because of the important part computers play in automation, this chapter will deal mainly with the special problems that arise in the design, procure­ment and application of digital computer control systems

The past growth of the field of computer control has shown an exponential trend that is typical of a newly introduced technology 2 The increase may eventually be expected to slow down to more of a linear rise as the demand stabilizes, however, it is likely that the limiting influence will not be the usual market saturation but rather the lack of a sufficient number of knowledgeable applica­tions engineers

The history of computers in control shows an early and continuing preponderance in the petroleum and other chemical industries with applications in electric-power and metals production running not far behind 3 On the other hand, computer control of nuclear facilities is among the

CHAPTER CONTENTS

8 1 Introduction 192

8 2 System Comparisons 193

8-2 1 Analog Control Systems 193

8 2 2 Hybrid Control Systems 194

8-2 3 Digital Control Systems 194

8-3 Degree of Automation 194

8-3 1 Operator Control 195

8-3 2 Monitored Operator Control 195

8 3 3 Operator Guidance 195

8-3 4 Automatic Control 195

8 4 Scope of Automation 195

8-4 1 Conventional Processes 196

8 4 2 Nuclear Processes 196

8-4 3 Auxiliary Processes 196

8-4 4 Start Up and Shutdown 196

8 4 5 Nonprocess Functions 197

8-4 6 Typical Applications 197

8-5 System Design 197

8-5 1 Schedule 197

8-5 2 Preliminary Design 198

8-5 3 Program Description 198

8-5 4 Redundancy 199

8-5 5 Cost Estimates 200

8-6 System Specification 201

8-6 1 Introductory Sections 201

8-6 2 Central Processor 201

8-6 3 Process Input/Output 203

8-6 4 Standard Peripherals 205

8-6 5 Software 207

8-6 6 Environmental and Miscellaneous

Characteristics. 208

8 6 7 Other Sections of the Specification 209

(a) Acceptance Tests. … . . 209

(b) Installation. . . . 209

(c) Training…………………… . 209

(d) Appendixes. … 209

8-7 Current Plant Designs 209

8-7 1 Douglas Point 210

8 7 2 Marviken 210

8-7 3 Wylfa 210

8-7 4 Dungeness “B” 210

8-7 5 Hinkley “B” 210

8-7 6 Prototype Fast Reactor 210

8-7.7 Pickering 210

8-7 8 Gentilly 210

References.. . ..210

Bibliography. . . . . . 211

Fig. 8.1—Analog feedback control system

Fig. 8.2—Analog automatic control system

least developed of the industrial areas, a state of affairs due largely to the plant builders’ and the operators’ uneasiness over acceptance by licensing authorities 4 Once this barrier has been surmounted, we expect nuclear-plant applications to catch up quickly with the rest of industry Moreover, the combination of an expanding competitive nuclear power business, the unusually thorough mathematical representa­tions of nuclear reactors the continuing improvements in computer speed and reliability, and the ability of the computer to solve complex problems affords an un­precedented opportunity for the engineer to apply advanced control methods 5

Control systems can be described in terms of the extent to which they provide automatic plant operation and the kind of equipment used to do it First, a system type may be classed by whether its primary implementation method is analog, digital, or a combination of both. This classifica­tion provides an indication of automation since it implies certain automation capabilities. A second classification concerns the degree of automatic control provided, the criterion being how completely the equipment replaces the human operator’s decisions and actions Third, the system can be described according to its scope, і e, the proportion of the total plant that is under automatic control These three categories will be discussed further in the following section

An underlying objective of automation is improved economics of plant operation, and the anticipated amount of improvement is the measure of the justification for control-system cost This objective will be achieved in different ways depending on the mission of the facility. A power-producing plant with proven components needs a
redundant system with moderate data handling to provide maximum operating continuity, whereas a prototype re­quires less emphasis on high plant factor and more on data acquisition and analysis The effect of facility mission on control-system design will be treated later in some detail because of its heavy influence on system size and cost

10- 4.1 Installation Hardware

(a) Conduits. Two basic types of conduit are available, aluminum and steel, other types, such as plastic, are used occasionally. In addition, plastic-coated steel and aluminum are finding wide use where corrosion is a problem. Aluminum is light in weight, free from corrosion by moisture, and easy to install, whereas steel is a far better shield against magnetic fields and has greater strength

Where conduit is to be run through concrete (such as in biological shields), steel should be used since many concrete mixes eventually corrode aluminum, particularly with the presence of moisture If radiation levels and conduit temperatures permit, plastic coated steel conduits yield the best service in damp locations Drain holes should be drilled at low points in exposed conduits to permit any accumu lated moisture to escape, and unexposed conduits, such as shield penetrations, should be arranged so that moisture cannot collect in interior points Conduit should be sized so that the installed wire cables, including allowances for expansion, fill no more than 40% of the conduit area to ensure ease of expansion and repair Information on conduit sizes and available fittings may be found in any equipment manufacturer’s catalog

Particular attention should be paid to joints between aluminum and steel conduit, and, wherever possible, these should be avoided because of the possibility of electrolytic corrosion If such joints must be made, they should be located where they can be easily inspected and protected from moisture

(b) Wiring Trays and Supports. Wiring trays and sup­ports are used wherever it is necessary to route a great number of large-diameter wires to a particular location and still allow easy access to the wiring Solid covered trays are used for instrumentation wiring and open mesh trays for power wiring

Care should be taken that heat buildup in enclosed power-cable trays does not lead to deterioration of insula­tion since power cables in enclosed trays should be operated at a lower rating than those in free air When trays are installed, they should be bonded together to ensure ground continuity and grounding to the main building ground This tan be accomplished by several methods, such as welding and brazing the sections together, using bolted joints, or by running a ground wire along the tray sections and bonding each section to the wire with a suitable clamp (see Sec 10-5).

10- 4.2 Signal and Control Cables

(a) Power-Distribution Cables. Since power cables for instrumentation do not normally carry high currents or high voltages, a reference, such as the latest National Electrical Code (NEC), should be used to determine minimum standards of conductor type, size, etc, and installers should be aware of signal cables in the vicinity of power lines so that proper shielding measures (as shown in Sec 10-5) can be taken. In addition to mterequipment cabling, power lines in mtrarack wiring should be enclosed in wireways wherever possible to improve shielding

(b) Unshielded Control Cables. The present practice in the electrical power industry of standardizing field wires to No 12 or No. 14 AWG with bulky insulation can cause

Table 10 2—Permanent Effect of Gamma Radiation on Physical Strengths of Cable Coverings* H D. C. B. C. K 90° C N F. C. E Sill- Neo- PVC Poly SBR CLPE EPDM Butyl oil base CLPE EPM cone PVC prene CSPE CPE Tensile Strength Original, psi Retention after 2114 2213 1520 2045 1455 798 804 2272 872 1191 2601 2544 2113 2170 irradiation, % 5 x 10s rads 110 96 98 122 104 96 121 102 101 76 80 104 106 112 5 x 106 rads 104 98 100 112 97 58 103 97 106 100 88 98 113 98 5 x 107 rads 79 123 82 101 93 + 98 70 119 100 61 77 124 135 1 x 10s rads 83 118 40 95 79 t 71 59 90 * 200% Modulus Original, psi Retention after 2260 2000 588 1767 1033 520 335 1260 730 859 2415 930 884 626 irradiation, % 5 x 10s rads 94 95 106 125 100 103 121 96 116 75 81 107 116 108 5 x 10[22] [23] rads 90 98 121 115 94 69 126 102 127 112 95 103 156 152 5 x 107 rads § 150 § 120 t 121 108 i? 98 160 203 § 1 X 108 rads § § § § + 103 s? § t Elongation Original % Retention after 260 640 460 270 470 450 870 480 300 290 250 550 560 670 irradiation, % 5 x 10s rads 115 103 93 104 111 93 97 90 96 107 100 96 89 99 5 x 106 rads 115 103 96 96 102 87 90 96 81 90 80 93 86 63 5 x 107 rads 31 70 48 47 + 71 58 41 34 40 46 59 18 1 x 10’ rads 19 2 33 37 32 t 53 25 26 t t

Table 10.3—Permanent Effect of Gamma Radiation on Dielectric Constant (k’) of Cable Coverings’^ Dose, rads Measured after 2 hr, °С PVC H. D. Poly. SBR C. B. CLPE C. F. EPDM Butyl 90° C oil base N. F. CLPE C. F. EPM Silicone k’ (S. I.C.) , 40 volts/mil, 60 Hz None 23 4.90 2.58 3.32 3.58 3.37 4.35 3.44 2.25 3.47 3.11 75 6.82 2.52 3.84 3.44 3.19 4.21 3.27 2.30 3.49 2.96 90 7.32 2.51 t 3.04 3.18 4.14 3.09 2.30 3.44 2.98 % Change 5 x 10s 23 + 3 -1 +5 -1 -4 -2 +5 +7 +8 0 75 -4 -2 + 10 -2 -4 -2 0 + 3 0 -i 90 +52 + 1 t +4 +5 -2 +2 -4 + 3 -i 5 x 106 23 +4 + 39 +5 + 3 -9 -20 + 10 + 3 +8 +29 75 +6 +42 +6 -7 -6 0 -4 -7 + 3 -8 90 t + 132 t +4 +5 0 + 3 +4 + 3 -8 5 x 10’ 23 +21 + 36 + 1 + 3 -7 -20 +6 + 3 + 10 +2 75 +41 + 39 -9 -1 -8 § + 1 -1 +6 + 1 90 t + 104 t +9 +2 § + 10 +9 +9 0 1 x 108 23 +59 -6 + 1 +2 + 1 § + 7 +2 +7 +6

*See note Table 10.2.

tThe high dielectric constants of the neoprene-, CSPE-, and CPE-based jacket materials were not significantly affected.

$Loss higher than limit of bridge.

§No test, sample degraded. [24]

Table 10.4—Permanent Effect of Gamma Radiation on d-c Resistivity of Cable Coverings* Dose, rads Measured after 2 hr, °С PVC H. D. Poly. SBR C. B. CLPE C. F. EPDM Butyl 90° C oil base N. F. CLPE C. F. EPM Sili­ cone Neo­ prene CSPE CPE D-C Resistivity, 100 Teraohms-cm, 500 volts D -c None 23 0.15 240 2.3 70 12 76 15 141 71 0.2 10~3 0.2 10“2 75 10"4 25 10~3 40 0.3 0.2 1.2 68 1.3 10~2 10"4 1 0-3 1 0 /4 90 10 4 20 10 4 37 0.3 0.1 0.1 50 1.0 10"3 10~6 10 4 10’3 % Change 5 x 10s 23 -28 m 1 +50 + 33 -20 0 -i -4 + 11 +57 -31 -14 -46 75 -90 -32 +48 +50 + 32 -14 + 100 -3 + 10 0 -34 -32 -55 90 -23 -90 -6 -33 -29 -51 + 100 -3 0 +52 -85 -54 + 198 5 x 106 23 -48 -70 + 13 -59 -4 0 -1 -4 + 38 0 + 15 -5 0 75 + 10 -99 +40 + 17 -8 -84 +66 -3 -9 +25 +4 -17 0 90 -47 -92 0 -43 -51 -98 +90 -3 0 +15 +415 -82 + 19 5 x 107 23 -67 -81 +48 -68 +5 3 -82 -5 -4 +25 +60 0 0 -14 75 + 100 -80 +250 -52 -34 t + 33 -4 -7 +20 + 11 -17 -92 90 +27 -99 + 100 -75 -79 + +25 -3 -40 +64 + 390 -75 -85 1 x 108 23 + 120 -70 +58 -7 +60 t + 35 -8 0 +60

Table 10.5—Permanent Effect of Gamma Radiation on Flame Resistance
of Thin-Wall Wires in Underwriters Laboratories Flame Test*+

H. D. C. F. 90° C C. F.

Poly./ SBR/ C. B. EPDM/ Butyl/ oil base/ N. F. ЕРМ/ Silicone

PVC PVC neoprene CLPE neoprene neoprene CSPE CLPE CPE glass

Dose, rads	0	10s	0	10®	0	10s	0	10s	0	108	0	10s	0	10s	0	108	0	108	0	108
Results	p	p	F	P	F	F	F	F	p	p	F	F	P	p	F	F	P	P	p	p
% flag destroyed	0	0	100	0	100	100	100	100	0	0	100	20	0	0	100	100	0	0	0	0
After burn, sec	0	0	180	0	52	60	180	100	0	0	50	80	0	0	180	180	0	0	0	0

*See note Table 10 2 tP, pass, F, failure

Table 10.6—Threshold (in rads) of Gamma Radiation Damage for Elastomer-Based Cable Coverings*

H. D. C. B. C. F. 90° C N. F. C. F. Sili — Neo­Property PVC Poly SBR CLPE EPDM Butyl oil base CLPE EPM cone PVC prene CSPE CPE

Tensile strength

108

108

5 x 107

108

108

5 X 106

10s

5 x 107

108

5 X 107

5 x 107

5 x 107

5 x 107

5 x 10

Elongation

5 x 107

5 x 106

5 x 107

5 x 107

5 x 107

5 X 106

108

5 x 107

5 x 107

5 X 107

5 x 107

5 x 107

5 x 107

5 x 10′

Rate of oxidation

5 x 106

>5 x 107

>5 x 107

>5 x 107

5 x 106

>5 x 107

5 x 106

5 x 107

5 x 105

5 x 106

5 x 106

5 x 107

5 x 10′

Dielectric loss

5 x 107

5 x 10s

108

108

108

5 x 106

108

5 x 105

108

108

5 x 107

5 x 107

5 x 107

5 x 10

Electric stability

5 x 10s

>5 x 107

5 x 10s

>5 x 107

5 x 107

5 x 10s

5 x 107

5 x 107

>5 x 107

>5 x 107

5 x 105

5 x 10s

5 x 106

5 x 10′

Dielectric strength

5 x 107

5 x 107

5 x 107

108

CO О Л

5 x 106

108

>106

>108

>108

5 x 107

5 x 10s

5 x 10s

5 x 10

Overall threshold of damage

5 x 105

5 x 106

5 x 105

5 x 107

5 x 107

5 x 106

5 x 107

5 x 106

5 x 107

5 x 105

5 x 105

5 x 106

5 x 106

5 x 10′

Highest dose still serviceable

5 x 10‘

5 x 107

5 x 107

108

108

5 x 106

108

108

108

5 x 107

5 x 106

5 x 106

5 x 107

5 x 10

*See note Table 10.2.

Table 10.7—Suggested IEEE Nuclear Environment Classification for Elastomer-Based Cable Coverings Temperature Class Radiation class O(90°C) A(105°C) B(130°C) 1 (9 x 104 rads) Silicone (see Note 1) Silicone (see Note 1) Silicone 2 (9 x 10s rads) Butyl/neoprene, CSPE, CPE, and H D Poly See below None 3 (8 8 x 10s rads) EPDM, EPM, oil base, N. F CLPE, and С В CLPE EPDM, С В CLPE, and EPM None 4 (8 8 x 109 rads) None None None 5 (101 0 rads) None None None

Notes

1 Dimethylsihcone based insulations (IPCEA S-19 81, Par 3 17) are suitable at their usual 130°C temperature rating only in low-radiation environments because of their sensitivity to steam and poor resistance to oxidation after irradiation Blodgett and Fisher rate them only in classes Ol, Al, and B1

2 Carbon-black (and probably clay-filled) cross-linked polyethylenes and clay-filled EPM — or EPDM based insulations are suitable at 105°C up to class 3 radiation levels when protected with suitable flame-resistant braids (such as the glass construction used in Blodgett and Fisher’s study) or flame and water-resistant asbestos constructions Blodgett and Fisher rate these two materials for classes Ol, 02, 03, and Al, A2, and A3

3 Butyl and high-density polyethylenes with neoprene, CSPE, or CPE jackets or the CPE as integral insulation jackets are suitable at their usual 90°C temperature rating only up to class 2 radiation levels Blodgett and Fisher rate these systems only for classes Ol and 02

4 Nonfilled cross linked polyethylenes and oil-base insulations, when protected by a neoprene, CSPE, or COE jacket, are suitable at their usual 90°C temperature rating up to class 03 Blodgett and Fisher rate these systems for classes Ol, 02, and 03

5 SBR and PVC-based coverings are suitable only at relatively low temperatures and radiation levels In particular (IPCEA S 61-402, paragraphs 3 7 and 3 8), PVC’s are sensitive to hot water and steam when exposed to more than 5 x 105 rads

serious installation problems if the instrument-cabinet terminal blocks are not properly sized The design engineer and instrument-cabinet manufacturer should allow ample space m the cabinet for terminal blocks, conduits, and wireways to accommodate the large-size field wires Single­conductor field wires with diameters of % to ^16 in are being used m power-station design

Several types of single conductor wire with small- diameter plastic insulation are durable and meet all the environmental requirements for power-station design

Where smaller (No 18 to No. 22 AWG) wires are used, they should normally be in the form of cables having a number of twisted pairs covered by an outer sheath, with one pair assigned to each circuit function Avoid having several circuits tied to a single ground conductor since, if this conductor fails, a number of circuits will be put out of commission instead of only one

It is evident that only power cables, switch commands, relay operating signals, and lines that can tolerate some cross-talk, such as communication lines, should be run m unshielded cables

If one of these lines is terminated in a terminal strip or block, solderless crimp connectors may be used, if the line terminates in a connector, solderless or solder-type termina­tions may be used. When wires are terminated in a connector, covering each wire with teflon tubing, shrink tubing, or other insulation will decrease the probability of shorts

In general, unshielded wiring is much easier to install than shielded and, if standards such as those referenced in other sections of this chapter are followed, should create no problems

(c) Instrument Signal Cables (Multiconductor, Shielded). Because of cross talk, spike induction, and other interference problems, it is important to consider the routing of each cable with respect to its electromagnetic environment Mixing of low-level signals, relay command’ servomotor control currents, and communication cables m the same conduit or raceway results in interference problems whether shielded cable is used or not Good practice dictates that instrumentation cables be separated physically according to signal level and function as well as electrically by shielding etc, wherever possible In critical circuits, such as reactor-control circuits, separate each channel’s measurement and control function from all others This will result m at least three sets of separately run conduit, color coded or identified in some way If this policy of separation is followed along with coincidence safety logic in the control-instrumentation design as well as in wiring layout, any portion of the control system may be disconnected without causing a scram

Isolate wiring according to function Cables carrying high currents or voltages should be isolated from those carrying low currents or voltages, and cables carrying interference-producing signals should be isolated from those carrying direct current A designer should use a separate

Table 10.8—Installation Symbols Commonly Used in the Nuclear Power Industry

© ©"

Winding connection З-phase ungrounded Winding connection З-phase grounded Piping

Resistor Capacitor Battery Alternating-current source

©

1———— і

Primary flow line

f-

■i

Secondary flow line

<

Thermocouple

ASMF Boiler Code line Control air line Instrument capillary tubing Flexible hose Valves Gate Globe Check Stop check Plug Angle Manual flow controller

Thermal element Conductor and junction 2-conductor cable Shielded 2-conductor cable Coaxial cable Ground Basic contact assemblies Electromagnetic actuator with mechanical linkage Push-button switch Coaxial connector Transformer Fuse

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MO©

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nnnnn ronnn AIR CORE IRON CORE

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Butterfly Relief

Circuit breaker

Semiconductor rectifier diode

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Electromatic relief

Meter

Three-way

Rotating generator

Four-way

Rotating motor Winding connection 1-phase

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Throttle

Table 10 8— -(Continued) Bleeder trip Local mounted transducer electric to pneumatic Locked open 10 —CX—’ Amplifier controller Locked closed L C —ж—• Miscellaneous Instruments Self contained Flow meter Control (opens on air failure) I Ob T Sight flow indicator Control (closes on air failure) —i? i—« In line flow indicator Air lock AL Л -Ль- Flow nozzle Operators Flow orifice Diaphragm -Ль- Restricting orifice /lJov Electric motor -Ль- /povN Thermocouple Nonelectric power Resistance bulb -ЬКЬ- Float —Ы<н Sample cooler Manual trip and reset -Ль- 1 /sv Sample nozzle Solenoid —Л— Drain trap Damper with electric operator і i T® u Manometer Damper with air operator Basket strainer Instruments Local mounted 00 Hose connection Panel mounted | PI | PS | Air relay ^-BOARD Annunciator alarm Н00ХХ SYMBOL N/ Remote manual control Local mounted transducer Air switch pneumatic to electric

AC

conduit for all low-level (detector, thermocouple, etc.) signals, a separate conduit for high-level control signals containing shielded wires, a separate conduit for relay and contact closure leads, and a separate conduit for a-c and d-c power distribution.

If every precaution is not followed, scrams mav be caused by arc welders or other noise-producing devices, such as switching d-c circuits, when placed near the detector cables.

Concerning the signal and control cables, each cable should carry only signals of the same type and, for instrumentation purposes, should have at least an overall shield (either braid or metal foil) for each group of conductors In all instances the cable shielding should have an insulating layer over the shield to provide isolation from ground-loop currents likely to be circulating in the outer conduit. Each of the two most common types of shields (braided and foil) offers different degrees of shielding protection. The braided type of shield offers good protec­tion for low-level signals. However, because of the effect of leakage capacity through the braided shield to ground, common-mode reflection suffers, and something better is needed for noise-free transmission of microvolt-level signals. Lapped foil shields have been developed for this purpose, and this type of solid-foil shield, plus a low-resistance drain wire, reduces the leakage capacity from about 0.1 to 0 01 pF/ft, typically. In addition, the foil shield improves shield-to-ground electrical leakage characteristics, rejection of magnetic pickup, and shield-resistance characteristics, and reduces termination problems

Conductor pairs within the cable should be of the twisted variety since this in itself reduces interference as much as 15 dB [25] The use of balanced, twisted pairs is even more effective, resulting in an interference reduction of up to 80 dB. The foregoing techniques were applied in the construction of the Ballistic Missile Early Warning System (BMEWS), where many different types of cables were located in close proximity to one another. In this system inherent shielding of the cableways provided 6-dB attenua­tion, twisting of power and other cables provided 26 dB, and the use of balanced, twisted pairs added another 80 dB

Because instrumentation cables must not be considered separately from the system in which they are to be used, the designer should consider terminating all cables carry ing signals having frequencies greater than 10 kHz with their characteristic impedance to avoid end reflection. Termina­tion of signal cables depends on the type of cable and the signal levels involved. In general, cables other than coaxial can be terminated using color-coded crimp connectors of the “ring” type and affixed to terminal strips Each end of a conductor should also be marked by attaching a piece of plastic sleeving bearing the wire designation number as shown on the system interconnection diagram.

Wires within a conduit should not exceed code limits to ensure easy cable pulling. No splices should be allowed except in appropriate junction boxes [see Sec 10-4.1(a)] . The conduit “fill” should not exceed 40%, including planned additional space reserved for system changes. When cable is pulled through conduit, excessive stress should not be placed on the cables since this may result in damage to insulation in regular wiring or changes of impedance in coaxial cables. Spare conductors should be installed in each cable to permit system expansion. As a rule, running 10 to 15% more conductors than required seems to work well 1 his allows for additions without raising the cost exces­sively. However, the type of reactor installation (power, experimental, etc.) may alter this general rule.

Termination of thermocouple leads is a special case, and the manufacturer’s instructions should be followed to ensure that there are no error currents produced by improper terminations In addition, thermocouples should be kept away from cables carrying high current or voltage signal levels Self-balancing temperature recorders respond too slowly to be affected by transients on thermocouple leads. However, electronic time-sequential multiplexing of large numbers of thermocouples into a device (such as a computer) requires that transients on the thermocouple leads be eliminated since sampling of a particular thermo­couple may occur when the signal level is being influenced bv a transient.

(d) Coaxial and Triaxial Cables. Coaxial and triaxial cables require care in selection and termination because signal levels are of the order of 1 mV or less Triaxial cables provide additional low-frequency’ (<100 kHz) shielding attenuation of 20 to 40 dB over coaxial cables, and additional benefits, such as low leakage, may be gained by appropriately driving the inner shield as explained in Sec. 10-5.5(a) Regarding installation of these cables, it is safe to use BNC type connectors of either the crimp or solder style up to 500 volts d-c. (The crimp type is popular.) Above 500 volts d-c, MI1V series connectors may be used to voltages of 5000 volts d-c, except where high-frequency pulses are present At very high pulse rates (>1 MHz), the connector impedance must match the cable, and so other types of connectors must be chosen. When cable connectors are being installed, care must be used to ensure that there are no loose ends of the shield braid to cause shorts or lower the breakdown resistance of the connector After the cable has been assembled, the test procedure outlined in Table 10.9 is recommended

Table 10.9—Cable-Testing Procedure Operating voltage Test procedure <600 volts d l 2 times rated voltage plus 1000 volts applied for 1 min. >600 volts d-c 2 25 times rated voltage plus 2000 volts applied for 1 min

Since magnetic and electric fields are responsible for most interference problems below approximately З МН/, low-frequency (60 II/) pickup should be guarded against b using steel conduit around low-level coaxial and triaxial cables The steel effectively attenuates both magnetic and electrostatic fields at all frequencies

At termination ends of coaxial or triaxial cables, each connector should be marked with its appropriate print number as well as the number of the mating connector for the particular cable An appropriate marking device is a plastic sleeve wrapped around the cable end and bearing the necessary information

When triaxial cable is used, connector assembly is more critical than when BNC is used, and greater care must be taken m testing the completed cable The tests in I able 10 9 should be applied in this case not only between center conductor and inner shield but also between the inner and the outer shield to ensure proper connector integrity I or extra protection a quantity of silicone grease — may be used inside the connector to provide additional insulation and to prevent accumulation of moisture within the connector

(e) Containment Penetrations. Penetrations for signal, control, and power tables m the leactor containment have been custom designed Custom designed penetrations, in many cases, required assembly at installation and disassem bly for repair Man) problems experienced with contain ment penetrations resulted from field-assembly conditions Although the problems experienced yvith field-assembled penetrations were often similar (e g, difficult installation, leaking seals, and poor wire termination), the variety of
custom designs prevented universal solutions from being applied to similar problems

I or greater reliability and ease of installation, several manufacturers have designed and now fabricate preasscmbled and pretested electrical penetrations These penetrations can be supplied with seals that are compatible with a variety of ambient environmental conditions (tem­perature, moisture, and nuclear-radiation level) Penetra­tions can be supplied with electrical conductors ranging from unshielded control and power wires to coaxial, triaxial, and other types of shielded cable Wire termina­tions are ayailable that range from pigtails and pressure or crimp splice tubes to special high-voltage and shielded connectors 1 he preassembled penetrations are tested at the factory for leak rate, conductor continuity, and insulation resistance The assembled and tested penetrations can be equipped with a leak-monitor pressure gauge and pressur i7ed with inert gas, thus allowing the penetration to be monitored for leaks during shipment and installation as w’ell as during operation. The preassembled penetration can be supplied for field installation with a welding ring or a bolted flange Pigure 10 14 shows some of the features available in preassembled penetrations

The basic criteria for judging a system specification are the same for a computer-based control system as for analog equipment. There are, however, additional items in a computer system which even an experienced designer may sometimes overlook. It is therefore advisable for the specification writer to have a checklist of items available or to consult the procurement documents of a successful control system

A complete outline of the sample specification is presented in Table 8 4. In this section a sample specifica­tion is presented and discussed section by section. The sample shows what should be included in a specification that requires the manufacturer to provide computer sys­tems programs but not the control software. Not all the items shown m the sample will appear in every specifica­tion. Many systems will not require double precision and floating-point hardware, memory protect, automatic re­start, etc On the other hand, the sample specification does not include special-purpose electronics that might be supplied by the computer manufacturer

We stress the point that the following specimen is for illustration only. It would not be used for an actual procurement because

1. There will usually be some items that are undergoing improvement and field testing of which the specification writer is unaware. A “functional” specification for such items may allow a supplier to offer equipment that would not meet strict performance specifications but is actually best suited to the application.

2. The detailed requirements in the specimen represent performance at or near the state of the art In the interest of a lower pnce and better competition, these should be relaxed wherever possible to correspond to the needs of the plant

3. System suppliers are continually developing execu­tive programs and adding applications programs to their software packages. By using as much of the supplier’s proven control software as appropriate to the application, the designer can realize a considerable project cost saving

4. Design engineers often prefer to evaluate computer speed by finding the running time of a bench-mark program that includes arithmetic, logic, transfer, and mput/output instructions in about the proportions that they will occur in the actual application. Besides providing a good functional criterion for acceptance, this method can reveal deficiencies in computer architecture that might not show up if only the operating speeds of the individual computer functions were analyzed.

8-6.1 Introductory Sections

The specification should begin with a short descnption of the reactor the computer is to be associated with and what the computer is expected to do. The bidder must be given a thorough and unambiguous concept of the whole system. Following this summarizing statement, the broad specifications of the computer itself should be described. A list of the major equipment should be presented in the order in which the equipment is described in the body of the specification.

The sample section below shows how the introductory sections of the system specification might be written.

SPECIFICATION FOR XPR-1 COMPUTER SYSTEM

SUMMARY

This specification details the requirements for the digital — computer system to be installed as an integral part of the XPR-1 instrumentation and display system The computer system will operate on-line to the reactor and provide the necessary equipment for reactor systems support, analysis, control, and reporting

This application supports the operation of XPR-1 (Experimental Power Reactor Number One), a 1000 MW(e) nuclear facility designed for the generation of electric power The computer system will support this facility by providing data acquisition, analysis, control, display, and reporting The reactor is characterized by both on—off and continuous data-acquisition and control processes On—off operations are typified by block valves, start—stop pump, supply utilities, etc Continuous monitoring and control is applied to neutron flux, temperature, flow, etc The success of this installation will depend on the reliability of the system, thus, meeting the reliability and quality assurance requirements is important

1.0 GENERAL DESCRIPTION

This specification describes a general-purpose digital computer of the binary, core-memory, parallel, single-address type with indirect and indexed addressing The computer system is to be used as the basis of a real-time control system performing control functions in the operation of a nuclear power reactor The computer system is required to respond to both analog and digital inputs, provide analog control signals, and store data in on-line bulk storage Operator communication is by keyboard and interactive cathode — ray tube display

2.0 MAJOR EQUIPMENT LIST

2 1 24-bit general-purpose computer with 16K of core memory.

2 2 250K word disk storage unit

2 3 100 line-per-minute line printer

2.4 300/100 character-per-second paper-tape reader/punch.

2 5 Two 21-in color cathode-ray-tube display consoles

2 6 An analog input facility for 2000 points.

2.7 A digital input facility for 2000 points

2 8 An analog output facility for 20 points

8-6.2 Central Processor

The requirements of the central processor are then listed. An acceptable range of word lengths, the result of a detailed analysis of data-handling and computation needs, is stated. The instruction set, memory requirements, and the

Table 8.4—Specification Outline (Summary Description)

5 13 Error control 5 14 Write lock 5 2 Line printer

5 2 1 Print speed 5 2 2 Number of columns 5 2 3 Character spacing 5 2 4 Character size 5 2 5 Character registration 5 2 6 Character set 5 2 7 Character replacement 5 2 8 Line spacing 5 2 9 Line registration 5 2 10 Paper handling

5.2.11 Ribbon

5 2 12 Printer cabinet soundproofing 5 2 13 Paper storage 5 3 Paper-tape reader/punch 5 3 1 Speed 5 3 2 Code

5 3 3 Tape take up and supply

5 4 Display—Alphanumeric and graphic

5 4 1 Display area 5 4 2 Phosphor 5 4 3 Spot size

5 4 4 Random positioning time

5 4 5 Positioning repeatability

5 4 6 Jitter

5 4 7 Resolution

5 4 8 Contrast ratio

5 4 9 Brightness

5 4 10 Vector data format

5 4 11 Vector end point registration

5 4 12 Vector writing rate

5 4 13 Character plot

5 4 14 Character sizes

5 4 15 Number of characters displayed

5 4 16 Aspect ratio

5 4 17 Intensity

5 4 18 Light pen

5 4 19 Keyboard

5 4 20 Memory

5 4 21 Enclosure

6 Software

6 1 Executive 6 2 Compiler 6 3 Assembler

6 4 Correction program 6 5 Diagnostic and utility programs 6 6 Input/output programs 6 7 Maintenance programs 6 8 Delivery form

6 9 Documentation

7 Environmental and miscellaneous characteristics

7 1 Temperature 7 2 Humidity

7 3 Power 7 4 Enclosure 7 5 Spare parts 7 6 Documentation 7 7 Reliability

7 8 Quality-assurance program

other items in this section must reflect the type of application whether it emphasizes data acquisition, data analysis, or process control Taken together, these items should also force the bidders to confine their offerings to heavy-duty industrial-grade equipment to the exclusion of light laboratory computers, desk computers, and machines designed for scientific or business data processing

The central-processor section of the sample specifica­tion is as follows

3.0 CENTRAL PROCESSOR

З 1 Core Memory

3 11 Word Length

The computer shall utilize a basic word length of 24 bits excluding memory parity and memory protect

3.1 2 Word Capacity

A minimum of 16,384 twenty-four-bit words of core memory shall be provided The computer shall be capable of field expansion to at least

32,768 words 3 1.3 Speed

The maximum read/restore memory cycle time shall not exceed 2 0 /isec 3 14 Parity

Memory parity shall be provided for each word in memory such that each transfer to, or from, memory is checked for correct parity An error shall cause an interrupt signal which identifies the location of the word in error 315 Protect

Memory protect shall be provided for each word in memory This bit shall be selectable under program control for each individual word When an at­tempted violation is detected by the computer, an interrupt signal shall be generated which identifies the location of the attempted violation

3 2 Arithmetic Unit

3.2 1 Hardware Arithmetic

Hardware arithmetic shall be provided to perform (1) single precision, (2) double precision, and (3) floating-point add, subtract, multiply, and divide

3.2 2 Execution Times

Execution times shall not exceed those listed below

	Single precision, fisec	Double precision, jusec	Floating point, Msec
Add	40	40	20
Subtract	4 0	4.0	20
Multiply	20	20	100
Divide	30	30	100

3.3 Addressing

3.3.1 Direct

The computer shall be capable of directly ad­dressing a minimum of 2048 memory locations.

3.3.2 Indirect

Multilevel indirect addressing shall be provided with a capability of reading a minimum of 32,768 memory locations. Each level ot indirect address shall add no more than one (1) memory cycle to an instructions execution time.

3 3 3 Indexing

At least three (3) dedicated index registers shall be provided

3 4 Priority Interrupts

At least 32 channels of multilevel hardware interrupt shall be provided such that any higher priority channel can interrupt the processing of a lower priority channel Each interrupt shall have a separate dedicated memory location (32 total) that contains space for the necessary instruc­tions to initiate a device service routine All interrupts except those assigned to the stall alarm and the power fail safe shall be capable of being individually turned on or off under program control

3 5 Direct Memory Access

A minimum of two (2) direct-memory-access (DMA) ports shall be provided Each port’s transfer rate shall be at least 500,000 twenty-four-bit words per second Multiplex capability for two channels at 250,000 twenty four-bit words per port shall be provided

3.6 Clocks

Two (2) basic clocks shall be provided, a real-time clock and an interval timer. The real-time clock shall have a basic frequency of 60 Hz. The interval timer shall have a crystal-controlled rate of 100 kHz with an accuracy of ±10 Hz per day. Additional registers shall be provided with the interval timer such that they can be loaded from memory under program control and incremented or decremented by the clock The timer shall provide an output signal (for use as an interrupt) when the register reaches zero.

3.7 Stall Alarm

A stall alarm shall be provided that detects machine looping or stalls. The method used shall be discussed in the response to bid.

3.8 Operator’s Console

An operator’s console shall be provided and shall include a tabletop working surface of at least 200 sq in.

3.8.1 Console Switches

A data entry switch corresponding to each bit in a word shall be provided. It shall be possible to enter data “manually” to “memory” and to all registers that are software accessible.

3.8.2 Display

The console shall provide for the display of the status of the following registers or their equivalent А-register (A-accumulator)

В-register (B-accumulator)

P-register (program counter)

I-register (instruction register)

M-register (memory address register)

X-register (index register)

In addition, the console display shall provide a run—halt indicator, an mput/output hold indi­cator, and a protect—violation indicator.

3.8.3 Console Teletype

A KSR-35 teletype, or equivalent heavy-duty machine, shall be interfaced to the computer for use as an operator’s console.

8-6.3 Process Input/Output

The process input/output are the communicating links between the plant and the computer. The multiplexer and converters are first specified individually as to number of

points, speed, and addressing. Then, because of the com­plex interrelations involved, a tendency toward functional specification is introduced, the requirements are placed on the entire input or output channel rather than on individual components Since the input/output list (see sample below) is a summary of many of the process interfaces, it is important to make sure that the two sets of requirements agree

The input/output sample specification is as follows

4 0 PROCESS INPUT/OUTPUT

4.1 Input/Output Channels

In addition to the direct-memory-access channel specified in Sec. 3 (Central Processor), the system shall provide a shared input/output (I/O) bus such that all peripheral devices can communicate directly with the computer

4.2 Speed

The I/O bus shall support I/O transfers at rates up to 30 kHz.

4.3 Input/Output Parity

I/O parity shall be provided. The system shall provide a hardware parity test for each I/O transfer and indicate all I/O parity errors by program interrupts

4.4 Input/Output Addressing

Capability for addressing a minimum of sixty-four (64) peripheral devices shall be provided. Each bidder shall indicate the standard I/O assignment by logical device number and hardware address number for all standard peripherals available for the computer

4.5 Digital Inputs

4.5.1 Capacity

The system shall provide for the input of at least two thousand (2000) binary signals. These signals take the following form

Type a 500 twelve (12)-bit voltage words. Type b 1000 one-bit binary voltages.

Type c 500 one-bit contact closures.

4.5.2 Logic Definition

Voltage inputs shall be positive true (1 = positive voltage). The following voltage range is required

+0.5 volt -0.0 volt +2.7 volts -0.0 volt

(The values specified are for conventional diode — transistor logic. It should be noted that high-level logic with improved noise immunity has recently become available from several sources. This high — level logic should be used whenever possible.) Contact signals shall be input as closure true Speed

The minimum transfer rates are as follows

50 type a inputs 1 kHz/channel

450 type a inputs 0 033 Hz/channel 48 type b inputs 30 kHz/channel (2 computer words)

952 type b inputs 1 Hz/channel (40 computer words)

500 type c inputs 0 5 Hz/channel (21 computer words)

4.6 Analog Outputs

4 6.1 Number of Channels

Twenty (20) channels of digital-to-analog output shall be provided

4.6.2 Output Range

The output shall be +10 volts full scale

4.6.3 Data Input

The data input shall be twelve (12) bits per channel fully buffered

4.6.4 Accuracy and Linearity

Accuracy and linearity shall be at least ±0 05% of full scale 5 mV

4.6 5 Monotonicity

The converter output shall be monotomc for each input bit change from negative (—) to positive (+) full scale.

4 6 6 Sag

The output sag shall be less than 1 mV/qsec

4.6 7 Slew Rate

The analog output rise time (10 to 90%) shall be 3 Msec or less for a full scale step change (digital) at the input.

4.6.8 Settling Time

The time required to settle to within 0.1% of the final value shall be less than 15 Msec for a full-scale step change (digital) at the input with 1000 pF capacitive load

4.6.9 Short-Circuit Capability

The output amphfier(s) shall be capable of sustain­ing a continuous short circuit to ground without damage.

4.7 Analog Inputs

The analog input system shall consist of a multiplexer(s), sample and hold amplifier(s), and an analog-to-digital converter It shall include all interface hardware required to make the analog system a functional part of the computer system.

4.7.1 Multiplexer

4.7.1.1 Input Switches

The input switches shall be field-effect transistors, either junction type (J-FET) or m e t a 1-ox і de-sem і со n d uctor (MOSFET). If MOSFET devices are sup­plied, each gate shall be protected from oxide rupture due to overvoltage.

4.7.1.2 Number of Channels

A minimum of 1000 input channels shall be provided. At least 500 channels shall be low level, the balance shall be high level (as defined in Sec. 4.7.1.6).

4.7.1.3 Input Configuration

Each input shall be differential-guarded (three-wire). All three inputs shall be commutated. A minimum of two (2) levels of subcommutation shall be pro­vided to isolate the input.

4.7.1.4 Sampling Rate

The following minimum sampling rates shall be provided

100 low-level channels, 5000 chan­nels/sec

100 high-level channels, 2500 chan­nels/sec

400 low-level channels, 10 channels/ sec

400 high-level channels, 10 channels/ sec

4.7.1.5 Input Impedance

The input impedance of an “off” channel shall be greater than ten (10) megohms when measured differentially or from either input to ground.

4.7 1.6 Full-Scale Input Voltage

The full-scale input range of the multi­plexer shall be as follows

Low-level inputs, ±10 mV High-level inputs, ±10 volts

4.7.1.7 Crosstalk

Crosstalk shall be less than ±0.01% of full scale on any channel when a 100% over­load is present on an adjacent channel.

4 7 18 Scatter

Channel-to-channel scatter shall be less than ±0.1% of full scale for the same input on all channels.

4.7.1.9 Common-Mode Rejection

Common mode rejection shall be at least 120 db from direct current to 60 Hz with a balanced source impedance. It shall be at least 85 db from direct current to 60 Hz for a 500-ohm unbalanced source impedance.

4 7 110 Maximum Common-Mode Voltage

The multiplexer(s) shall be capable of sustaining ±20 volts direct current or peak alternating current on any input without damage to the input switches and without turning on deselected channels.

4.7.1.11 Full-Scale Output Voltage

The full-scale output voltage shall be ±5 volts or greater for both low — and high — level inputs.

4.7.1.12 Address Modes

Three separate address modes shall be provided random, sequential, and dwell. Each mode shall be program initiated. The random access mode shall permit an external binary word to select any address at random. The sequential mode shall provide a fixed sampling pattern and be capable of operating from an internal or external clock. The dwell mode preselects one channel for continuous duty.

4.7.2 Analog-to-Digital Converter

4.7.2.1 Number of Bits

The converter shall provide 12 bits of information with the most significant bit representing the sign of the input data.

4.7.2.2 Conversion Speed

The total conversion time shall not ex­ceed 10/asec including sample time and hold time.

4.7.2.3 Aperture Time—Sample and Hold

The converter shall incorporate a sample and hold amplifier. The aperture time shall be 100 nsec or less.

4.7.2.4 Acquisition Time—Sample and Hold

The acquisition time shall not exceed 6 psec for a full-scale step input.

4 7 2 5 Sag—Sample and Hold

The permissible decay during hold shall be less than 4 of the least significant bit (lsb).

4.7.2.6 Accuracy

The transfer accuracy of the converter shall be at least ±0.05% ±’/ lsb

4.7.2.7 Monotonicity

The converter output shall be monotomc increasing (or decreasing) for a change from plus (+) to minus (-) full scale and from minus (-) to plus (+) full scale.

4.7.2.8 Linearity

The deviation from a straight line through plus (+) and minus (—) full scale shall not exceed ±0.1% t1/ lsb

4.7.2.9 Overscale indicator

One bit shall be provided to indicate an overscale input.

4.7.2.10 Display

A front-panel display that indicates the output word status shall be provided for troubleshooting purposes.

8-6.4 Standard Peripherals

Whereas the input/output includes the peripherals that are peculiar to process control systems, the standard peripherals include those items and their interfaces which are common to most computer systems The characteristics of each item depend on the application and often are compromises between programming efficiency and hard­ware cost This is particularly true of punched-card units and line printers. Only by experience can one estimate accurately the tradeoff between the programmers’ man­hours and the machine cost involved.

Although cathode-ray-tube (CRT) displays are be­coming more common, they have been used ш computers in so many different ways that no standard set of design criteria has yet been developed. It is therefore necessary, once the display content and formats have been decided on, to make a detailed analysis of the required data storage and transfer rates These are then related to the known capabilities of currently marketed hardware. Equipment to display both alphanumeric and graphic data should be studied carefully, a raster method may be required for one and beam steering for the other, with the result that two separate spares are needed if standby redundancy is a system requisite.

The standard-peripherals section of the sample specifi­cation is given below. The intermediate-speed bulk storage device may be either disk or drum, the specifications being quite similar. The disk was arbitrarily chosen for the example.

5. STANDARD PERIPHERALS

5.1 Disk Memory

A disk memory shall be interfaced to the computer. It shall utilize a fixed head per track design. The read/record heads shall not contact the disk surface.

5.1.1 Capacity

Disk capacity shall be a minimum of 12,000,000 bits.

5 1.2 Access Time

Worst case access time shall be less than or equal to 16 msec.

5.1.3 Error Control

Parity generation and error detection shall be provided for all transfers to and from the disk. The nominal error rate shall be no greater than 1 bit lost m 10* 0 data transfers.

5.1.4 Write Lock

Write lock shall be provided for at least 50% of the total storage capacity.

5.2 Line Printer

A line printer shall be interfaced to the computer. The printer will be used for on-line printing of alphabetic, numeric, and symbolic data.

5.2.1 Print Speed

Print speed shall be not less than 300 lines per minute.

5.2.2 Number of Columns

A minimum of 132 print positions (columns) across shall be provided.

5.2.3 Character Spacing

Character spacing shall be ten (10) characters to the inch (horizontally). The maximum cumulative error shall not exceed ±0.02 in. for the 132- column line.

5.2.4 Character Size

Nominal character size shall be 0.1 in. (vertically) by 0.066 in. (horizontally).

5.2.5 Character Registration

Vertical and horizontal registration shall be within a ±0 005-in tolerance.

5.2.6 Character Set

The following 64 characters shall be supplied A, В, C, D, E, F, G, H, I, J, K, L, M, N, О, P, Q, R, S, T, U, V, W, X, Y, Z, 1, 2, 3, 4, 5, 6, 7, 8, 9, ф, (,), ‘,

…….. /, -, +, &, L $, <, >, t,’, ", =, #, @, , %,

‘Л. ІЛл

5.2.7 Character Replacement

It shall be possible to individually remove and replace characters.

5.2.8 Line Spacing

Line-to-lme spacing shall be 6 lines per inch.

5.2.9 Line Registration

Line-to-lme registration shall be within ±0.005 in. nonaccumulative.

5.2.10 Paper Handling

The printer shall accept paper widths ranging from

2.5 to 18.5 in. The paper used shall be standard Z-fold sprocket feed. It shall be possible to use

6- part paper (multiple copy).

5.2.11 Ribbon

The printer ribbon shall be equipped with an automatic reversal feature.

5.2.12 Printer-Cabinet Soundproofing

The printer cabinet shall contain sound-deadening material with a minimum thickness of l/ in.

5.2.13 Paper Storage

Both input and output paper storage shall be provided.

5.3 Paper-Tape Reader/Punch

A paper tape reader/punch shall be interfaced to the computer

5.3.1 Speed

The system shall read/punch at a minimum speed of 300/100 characters per second.

5.3.2 Code

The system shall read and punch the standard

7- level ASCII code as described in ASA Standard X3.18-1967.

5.3.3 Tape Take-Up and Supply

The system shall utilize fanfold paper tape. Both supply and take-up bins for fanfold tape shall be supplied.

5 4 Display—Alphanumeric and Graphic

Two independent displays shall be interfaced to the computer. Each display system consists of a cathode-ray — tube assembly, vector generator, character generator, light pen, keyboard, and interface electronics.

5.4.1 Display Area

The display screen shall be not less than 19 in. across the color cathode-ray tube (diagonal or diameter measurement). The usable viewing area shall be not less than 12 sq in. All specifications shall be met everywhere in this area.

5.4.2 Phosphor

The CRT shall utilize a P22 phosphor (or equiv­alent) The faceplate shall have a boned safety shield installed.

5.4.3 Spot Size

The display-spot size shall not exceed 0.020 in. at the half-light points.

5.4.4 Random-Positioning Time

It shall be possible to display points at random. The maximum time required to position the beam and settle to within one spot width of the final position shall not exceed 16 /іsec.

5.4.5 Positioning Repeatability

The display-spot position repeatability shall not exceed ±0.3% of full scale independent of the previous position.

5.4.6 Jitter

The display-spot jitter shall not exceed ±0.2% of full scale over a time interval of 1 hr.

5.4.7 Resolution

The resolution in the x and у directions shall be ten (10) binary bits. The matrix defined is 1024 by 1024 points

5.4.8 Contrast Ratio

The contrast ratio for black and white shall be no less than 4 1 in an ambient light level of 20 ft-c.

5.4.9 Brightness

The brightness shall exceed 20 ft-lamberts in an ambient light level of 8 ft-c.

5.4.10 Vector Data Format

The display shall provide at least two (2) vector formats, one long and one short. Short vectors are defined as less than 1 m. The time required to display short vectors shall not exceed 5 Msec It shall be possible with the long-vector mode to specify either (inclusive) relative vector or absolute vector. In relative mode the x and у coordinates of the end point are given and the vector is drawn from the previous point. In absolute mode the x and у coordinates are specified and the vector is drawn relative to the origin of the position matrix.

5.4.11 Vector End-Point Registration

End-point registration shall be within ±0 03 5 in

5.4.12 Vector Writing Rate

The time required to write a vector shall be less than 50 msec regardless of length. The display intensity shall be constant irrespective of the length of the vector.

5.4.13 Character Plot

The character generator shall contain at least sixty-four (64) alphanumeric and symbolic charac­ters. The character set shall include those charac-

ters listed for the line printer in Sec. 5.2.6. The character generation time shall not exceed 10 jusec.

5 4.14 Character Sizes

At least two (2) programmable character sizes shall be provided.

5.4.15 Number of Characters Displayed

The display system shall be capable of displaying and refreshing not less than 1500 characters (50 Hz refresh rate)

5.4.16 Aspect Ratio

The character aspect ratio shall be not less than 4 3 (height to width) or greater than 3 2

5.4.17 Intensity

Three programmable intensity levels shall be sup plied for each primary color (red, blue, and green).

5.4.18 Light Pen

A photoelectric light pen shall be supplied for each display. It shall transmit an interrupt signal to the computer whenever a point on the display screen, within view of the pen, is intensified

5.4.19 Keyboard

An alphanumeric and symbolic keyboard shall be supplied with each display such that all defined characters can be entered from the keyboard. In addition, a function keyboard with at least 16 keys shall be supplied. A keyboard overlay that permits the selection of at least eight (8) different function groups shall be provided for all function keys. A separate overlay shall be supplied for each of the eight groups. Overlay code names shall not be supplied

5 4.20 Memory

A local refiesh memory capable of storing one frame of data shall be supplied with each display.

5 4 21 Enclosure

The display system shall be enclosed in a console cabinet. It shall have a table extending in the front below the cathode-ray tube. The cathode-ray tube shall be tilted slightly toward the back to facilitate operator viewing

The systems discussed in Secs. 9-5.4 to 9-5.7 use an a-c generator driven by an internal-combustion engine in combination with other components to provide a sustained power supply. Once operation is established with the engine as the prime mover, the time during which the alternator will operate is limited only by the available fuel supply.

The simple system shown in Fig. 9 8 is the basic configuration of a typical large standby auxiliary-power supply used in nuclear power plants. For a two-unit nuclear power station, a number of such large standby power sources sufficient to deliver as much as 20 MW when the normal auxiliary power is lost are required to maintain safe shutdown conditions or to provide power for the engi­neered safeguard auxiliaries during a loss-of-coolant accident.

The principles involved in the design and application of such power supplies are well known and are defined for nuclear power generating stations by standards [19] These principles or criteria are also applicable to the much smaller engine—generator units discussed elsewhere in this chapter.

9- 4.5 A-C and D-C Drive Motors

The normal dnve motor for a nonmterruptible rotating power supply can be either induction or synchronous The choice is usually determined by the frequency requirement of the output generator. The standard "a-c squirrel-cage induction motor is considered more reliable and can operate for a longer period with minimum maintenance. The slip rings and secondary excitation required by a synchronous motor require maintenance. However, brush­less synchronous motors are available and approach the reliability of induction motors, although at a greater cost.

The a-c induction motor can accelerate a greater load from rest than a synchronous motor can accelerate. The induction motor can be designed to have a very low slip value and thus can provide an output speed as little as 1% below that of a synchronous motor.

Synchronous motors provide a constant output fre­quency with constant input frequency. If a brushless synchronous motor is used, it is necessary to furnish an external exciter with voltage control and an external out-of-step protective relay, these are not required by an induction motor. Usually a large synchronous motor, when used with a stored-energy flywheel, is required to accelerate the flywheel into step. Thus, when large flywheels are used for stored energy, a synchronous motor that has several times the horsepower needed to drive the load may be required. In addition to the higher initial cost of the larger motor, the motor would be running normally at light load with decreased efficiency

The emergency drive motor for a rotating noninter­ruptible power supply can be a standard d-c motor with the possible addition of auxiliary fields for speed control. Usually the motor can have an intermittent rating since its duration of operation is relatively short, being limited by the d-c battery source used. Because the characteristics of common loads and supply voltages vary, automatic speed­regulating equipment should be furnished as part of the motor control. Read More Календарь Апрель 2024 Пн Вт Ср Чт Пт Сб Вс 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30   Рубрики 1 BIOFUELS A Look Back at the U. S. Department of Energy’s Aquatic Species Program: Biodiesel from Algae A. Worrall ABOUT THE AUTHOR ACCELERATOR DRIVEN SUBCRITICAL REACTORS ADVANCED BIOFUELS Advanced Biofuels and Bioproducts Advanced separation techniques for nuclear fuel reprocessing and radioactive waste treatment ADVANCES IN Advances in Biochemical Engineering/Biotechnology Advances in Biofuels Advances in Biorefineries Alcoholic Fuels Algae Energy All alternative energy Alternative transportation An Indispensable Truth An Introduction to Nuclear Materials AN INTRODUCTION. TO THE ENGINEERING. OF FAST NUCLEAR REACTORS ANNEX III. AHWR. Bhabha Atomic Research Centre, India ATOMIC ACCIDENTS BACKGROUND Bioenergy Bioenergy — Realizing the Potential Bioenergy from Wood BIOENERGY. RESEARCH:. ADVANCES AND. APPLICATIONS BIOETHANOL BIOFUEL'S ENGINEERING PROCESS TECHNOLOGY BIOFUELS BIOFUELS 1 Biofuels and Bioenergy Biofuels for Road Transport Biofuels from Agricultural Wastes and Byproducts BIOFUELS FROM ALGAE Biofuels Refining and Performance BIOGAS BIOGAS 1 BIOMASS — DETECTION, PRODUCTION AND USAGE Biomass and Biofuels from Microalgae Biomass Conversion Biomass Gasification and Pyrolysis BIOMASS NOW — CULTIVATION AND UTILIZATION BIOMASS NOW — SUSTAINABLE GROWTH AND USE Biomass Recalcitrance Biomasses identities Biotechnological Applications of Hemicellulosic Derived Sugars: State-of-the-Art Biotechnological Applications of Microalgae Biotechnology. for Fuels and Chemicals Cellulosic Energy Cropping Systems Comprehensive nuclear materials DESIGN FEATURES TO ACHIEVE. DEFENCE IN DEPTH IN SMALL AND. MEDIUM SIZED REACTORS Design of Reactor Containment Systems for Nuclear Power Plants ENERGY Energy Efficiency ENERGY SERVICES IN THE HINDU KUSH HIMALAYAN REGION Energy Storage Estimating Loss-of-Coolant Accident (LOCA) Frequencies Through the Elicitation Process EUROSUN 2008 EuroSun2004 EuroSun2008-10 EuroSun2008-11 EuroSun2008-13 EuroSun2008-2 EuroSun2008-3 EuroSun2008-4 EuroSun2008-5 EuroSun2008-7 EuroSun2008-9 EXAMPLES OF REACTIVITY-CONTROL SYSTEMS Exploitation des creurs REP Fast Breeder Reactor Programs: History and Status Fast Reactor Safety. (Nuclear science. and technology) Fertilization Frequency Response Testing. in Nuclear Reactors Fuels and Chemicals. from Biomass Gebaudetypologie Bayern Geothermal Energy GREEN BIORENEWABLE. BIOCOMPOSITES Handbook Nuclear Terms Handbook of biofuels production Handbook of Small Modular Nuclear Reactors Hydrogen — Fuel Cells Hydropower IAEA RADIATION TECHNOLOGY SERIES No Infrastructure and methodologies for the. justification of nuclear power programmes Innovative Biofibers from Renewable Resources Integral design concepts of advanced water cooled reactors Introduction to Nuclear Power Liquid Biofuels: Emergence, Development and LIQUID, GASEOUS AND SOLID BIOFUELS — CONVERSION TECHNIQUES Management von Biogas-Projekten Materials' ageing and degradation in. light water reactors Microbes and biochemistry of gas fermentation Modern Power Station Practice Natural circulation data and methods for advanced water cooled nuclear power plant designs Natural gas Neutron Scattering Applications and Techniques Nuclear and Radiochemistry Nuclear Back-end and Transmutation Technology for Waste Disposal NUCLEAR CHEMICAL ENGINEERING NUCLEAR ELECTRIC POWER Nuclear energy Nuclear Power and the Environment Nuclear power plant life management processes: Guidelines and practices for heavy water reactors NUCLEAR POWER PLANTS NUCLEAR POWER the PUBLIC Nuclear Reactor Design NUCLEAR REACTOR ENGINEERING Nuclear Reactors 1 NUCLEAR REACTORS 2 Others Particle Image Velocimetry (PIV) Passive Safety Systems and Natural Circulation in Water Cooled Nuclear Power Plants PHYSICS OF. HIGH-TEMPERATURE. REACTORS POWER Pretreatment Techniques for Biofuels and Biorefineries Principles of Fusion Energy PROCESS SYNTHESIS. FOR FUEL ETHANOL. PRODUCTION Production of Biofuels and Chemicals with Ionic Liquids Progress, Challenges, and Opportunities for. Converting U. S. and Russian Research Reactors Pumping Pyrolysis Radioactive waste management and contaminated site clean-up Recycling of Biomass Ashes Renewable Energy Products Rudiger Meiswinkel, Julian Meyer, Jurgen Schnell Second Generation Biofuels and Biomass Small modular reactors (SMRs) the case of Russia solar energy Solar Thermal and. Biomass Energy Sonar-Collecttors SonSolar Springer Series in Materials Science Study on Neutron Spectrum of Pulsed Neutron Reactor Sustainable Biotechnology Switchgrass Technologies for Converting Biomass to Useful Energy The Asian Biomass Handbook The Experimental Analyze Of The Solar Energy Collector The Future of Nuclear Power Thermal biomass. conversion and utilization —. Biomass information. system Thoria-based Nuclear Fuels Type of Membrane Contactor Suitable for CO2-O2 Exchanges in Culture Broth Vereinfachtes Verfahren WAS INTENTIONALLY LEFT BLANK Why We Need Nuclear Power wind power WORKSHOP ON NUCLEAR REACTION DATA AND. NUCLEAR REACTORS:. PHYSICS, DESIGN AND SAFETY Автономное энергообеспечение Альтерантивная энергия Альтернативные источники энергии и энергосбережение Без рубрики Биотопливо Ветровая энергия Ветрогенераторы, солнечные батареи и другие полезные конструк­ции Возобновляемые источники энергии ВОПРОСЫ ТЕОРИИ. И ИННОВАЦИОННЫХ РЕШЕНИЙ. ПРИ ИСПОЛЬЗОВАНИИ. ГЕЛИОЭНЕРГЕТИЧЕСКИХ СИСТЕМ ГЕЛИОЭНЕРГЕТИКА Другая энергия Зарядные станции Источники питания Источники энергии ИСУ Концентраторы солнечного излучения КРЕМНИЕВЫЕ СОЛНЕЧНЫЕ БАТАРЕИ Получение кремниевых пластин для солнечной энергетики Применение солнечной энергии Разное Солнечная электроэнергия Солнечная энергия Солнечная энергия — использование Солнечные батареи Солнечные коллекторы Солнечный ДОМ ТОНКОПЛЕНОЧНЫЕ. СОЛНЕЧНЫЕ ЭЛЕМЕНТЫ. НА ОСНОВЕ КРЕМНИЯ ФОТОЭЛЕКТРИЧЕСКОЕ. ПРЕОБРАЗОВАНИЕ. 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