A few of the world’s nuclear power plants are described briefly in this section to give the reader an idea of present computer applications These plants were selected because they are completed or soon will be, have some degree of computer control, and have been adequately discussed in meetings or publications. Pertinent data are summarized in Table 8.5. The dates listed are years during which the plant

goes on-line as a power-generating station, in some cases these have been inferred from other planned milestones, such as plant completion and date critical

8-7.1 Douglas Point

The CANDU reactor20 at Douglas Point, Ontario, is probably the earliest planned use of digital-computer control in a nuclear power plant At present the computer directly drives neutron absorber rods to control the reactor flux profile and indirectly adjusts power by providing the set point to the analog moderator level controller

As an assist to higher plant factor, the computer also modifies safety-circuit operation. The safety circuit alone will initiate scram if low coolant flow in any fuel channel is signaled, however, when the computer is operating, it inhibits the trip unless low flow is accompanied by high coolant outlet temperature.

8-7.2 Marviken

The Marviken Nuclear Power Plant,18 a 200-MW(e) station, will have a comprehensive set of sequence programs for start-up, running, shutdown, and refueling These are largely automatic with interspersed stopping points that require a manual command to proceed The control system will also automatically adjust the throttle valves in 32 superheat channels in the reactor core, a difficult procedure because a high-channel temperature requires resetting not only the affected channel valve but also those in several surrounding channels This is a good example of applying computer control where other means are inadequate.

8-7.3 Wylfa

Wylfa,21 a MAGNOX reactor station, is the first in a series of three plants in which computer-based data and display systems have been applied progressively more toward direct control as United Kingdom experience grows Wylfa has automatic turbine run-up

8-7.4 Dungeness “B”

In addition to automatic turbine run up, the Dungeness “B,”22 an advanced gas-cooled reactor station, will have complete start-up, from subcrmcal to power, under com­puter control with manual intervention required if the system encounters abnormal conditions The computer will also control, by rod movement, the ratio of outlet gas temperatures among five reactor zones This is a difficult control problem under all conditions of coolant flow and reactor power level

8-7.5 Hinkley “B”

Except for a different array of inputs and outputs, the Hinkley “B”13 is controlled similarly to the Dungeness “B ” Both stations are examples of the “dual-plant three — computer” configuration discussed m Sec 8-5.

8-7.6 Prototype Fast Reactor

Automatic computer control of reactor flux, coolant outlet temperatures, and steam-generator outlet tempera­tures is being considered for the prototype fast reactor,1 6 a 250-MW(e) sodium-cooled fast reactor facility This is the plant, cited before, in which a detailed economic and technical study resulted in a redundant computer system and a revision of principles to allow plant shutdown on complete control-system failure

8-7.7 Pickering

Nearly all the major reactor variables in the Pickering Nuclear Power Station,23 as in other Canadian plants, will be computer controlled. This includes flux profile, overall reactivity, boiler pressure, and the fueling process

8-7.8 Gentilly

As in the Pickering, most control of the Gentilly Nuclear Power Station2 4 will be by computer Of interest is the reactor’s large positive void coefficient, which will be compensated by moving a set of booster rods according to changes in plant power level Primary-coolant flow valves will also be automatically controlled as a function of power

REFERENCES

1 T J Williams, The Application of University Research to Industrial Process Control, in 22nd Annual ISA Conference, Chicago, 1967, Part 3, Paper No 5 1 ACOS-67, p 3, Instrument Society of America, Pittsburgh, 1967

2 Control Engineering Company, Compilations of Process Control Applications in Control Engineering, May 1962, September 1963, August 1965, September 1966, March 1967, July, 1968

3 M. A Schultz and F C Legler, Application of Digital Computer Techniques to Reactor Operation, in Proceedings of the Third International Conference on the Peaceful Uses of Atomic Energy, Geneva, 1964, Vol 4, pp 321 330, United Nations, New York, 1965

4 M A Schultz, Automatic Digital Computer Control, Sec 4 2, in Small Nuclear Power Plants, USAEC Report COO-284(Vol 2), pp 126 130, Chicago Operations Office, March 1967

5 W C Lipinski, Optimal Digital Computer Control of Nuclear Reactors, USAEC Report ANL-7530, Argonne National Labora tory, January 1969

6 J T Tou, Digital and Sampled Data Control Systems, McGraw Hill Book Company, Inc, New York, 1959

7 W D T Davies, Control Algorithms for DDC Instrum Pract 21 70-77 (January 1967)

8 К L Gimmy, On-Line Computers at the Savannah River Plant in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord Norway, September 1968, pp 727 737, Organization for Economic Cooperation and Development, Pans, 1968

9 A Pearson and C G Lennox, Sensing and Control Instrumenta tion, in The Technology of Nuclear Reactor Safety, Vol 1, Reactor Physics and Control, T J Thompson and J G Beckerley (Eds ), pp 285 416, M I T Press, Cambridge, Mass, 1964

10 J R Howard, Experience in DDC Turbine Start Up, ISA (Instrum Soc Amer) J, 13 61-65 (July 1966)

11 T J Glass Current Trends in Process Computer Software paper presented at Annual ISA Conference, Chicago, 1967, Paper No D2 3 DAHCOD67

12 R G Basten, Impact of Nuclear Reactor Control on the Structure of Computer Systems, in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp 517 533, Organization for Economic Cooperation and Development, Pans, 1968

13 M W Jervis, On Line Computers in Central Electricity Generat ing Board Nuclear Power Stations, in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp 51 78, Organization for Economic Cooperation and Development, Pans 1968

14 Computers in Control, Nucl Lng, 11 618 620 (August 1966)

15 J C Kite, How to Assure Maximum Performance in Redundant Computer Control Systems, paper presented at Annual ISA Conference, Chicago, 1967, Paper No D4 4-DAHCOD-67

16 N T C McAffer The Computer Instrumentation of the Prototype Fast Reactor, in Application of On Line Computers to Nuclear Reactors Seminar held at Sandefjord, Norway, September 1968, pp 351 379, Organization for Economic Cooperation and Development, Paris, 1968

17 Hinkley Point B, Nucl Lng, 12 26-28 (January 1967)

18 J Akesson, Techniques of Computer Application For the Marviken Nuclear Power Plant, in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp. 301-318, Organization for Economic Cooperation and Development, Paris, 1968

19. J. C Spooner, Real Time Operating System for Process Control, paper presented at Annual ISA Conference Chicago 1967 Paper No D1 1 DAHCOD 67

20 E Siddall and J E Smith, Computer Control in the Douglas Point Nuclear Power Station, in Heavy Water Power Reactors Symposium Proceedings, Vienna, 1967, International Atomic Energy Agency, Vienna, 1968 (STI/PUB/163)

21 D Wellbourne, Data Processing Control by a Computer at Wylfa Nuclear Power Station, m Advances in Automatic Control Convention held at Nottingham England, Apr 5-9, 1965, Paper 16, Institute of Mechanical Engineers London

22 A R Cameron, The On-Line Digital Computer System For The Dungeness “B” Nuclear Power Station, in Application of On-Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp 273 300, Orgamza tion for Economic Cooperation and Development, Pans, 1968

23 J E Smith, D>gital Computer Control System Planned For Pickering Nuclear Station, Elec News Lng, 39-41 (March 1967)

24 W R Whittal and К G Bosomworth, Dual Digital Computer Control System For the GentiUy Nuclear Power Station, 4th International Federation for Information Processing Congress, Edinburgh, Scotland, Aug 5 10, 1968, North-Holland Publish­ing Company, Amsterdam, 1969

BIBLIOGRAPHY

A comprehensive bibliography covering the general field of com­puter control is presented in T J Williams, Computers and Process Control, Ind Lng Chem, 62(2) 28 (February 1970)

Argonne National Laboratory, Liquid Metal Fast Breeder Reactor (LMFBR) Program Plan, Vol 4, Instrumentation and Control, USAEC Report WASH 1104, August 1968 Bullock J В and H P Danforth, The Application of an On Line Digital Computer to the Control System of the High Flux Isotope Reactor (HFIR) in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968 pp 459-478, Organization for Economic Cooperation and Development, Paris, 1968 Demuth, H В, J Bergstein, К H Duerre, and F P Schilling, Digital Control System for the UHTREX Reactor, in Apphca tion of On Line Computers to Nuclear Reactors Seminar held at Sandefjord Norway, September 1968, pp 621 642, Orgamza tion for Economic Cooperation and Development, Pans 1968 Ethenngton, H (Ed) Nuclear Engineering Handbook, McGraw Hill Book Company, Inc, New York, 1958 Freymeyer, P, and H Stein, Automation in the Control of Nuclear Power Stations, Kemtechmk, 11(9/10) 514 (September/

October 1969)

Harrer, J M, Nuclear Reactor Control Engineering, D Van Nostrand Company, Inc, Princeton, N J, 1963 Holland, L К , On Line Computer Experience with Boiling Water Reactors Trans Amer Nucl Soc 9(1) 264 (June 1966)

Moen, H, et al, Computer Control of the Halden Boiling Heavy Water Reactor, in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp 647 667, Organization for Economic Cooperation and Development Pans, 1968

Morin, R, Utilization of Digital Computers tor Starting and Running the EDP 3 Atomic Power Plant, Report AECTR-691, December 1967

Nuclear Reactors Built, Being Built, or Planned in the United States as of December 31, 1968, USAEC Report TID 8200 (19th Rev ), December 1968

Pearson, A Computer Control on Canadian Nuclear Reactors, in Application of On Line Computers to Nuclear Reactors, Seminar held at Sandefjord, Norway, September 1968, pp 123-144 Organization for Economic Cooperation and Develop ment, Pans, 1968

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

Williams, T J, A Manual for Digital Computer Application to Process Control, Purdue University Press, Lafayette, Indiana, 1966

8- 1 INTRODUCTION

The safe operation of nuclear power reactors requires that many of the instrumentation and control systems have a high degree of reliability. One factor in reliability is the integrity of the power source for the instrumentation and control power buses. This chapter provides the designer of instrumentation and control systems with sufficient in­formation to choose the power-source system best suited to his specific application and giving maximum support to the overall system reliability.

8- 1.1 System Requirements

The power sources most commonly used are electrical. Accordingly, this chapter deals mainly with them and only briefly with nonelectrical systems. The common combina­tions of static, rotating, and stored-energy system com­ponents are discussed. Battery-supported static inverter systems, which are among the most frequently used electrical source systems, are emphasized.

The systems discussed differ with respect to their degree of noninterruptibility, i. e., their capability to con­tinue operating under emergency conditions after normal source failure, the quality of their output, and their cost. The designer of instrumentation and control systems must first determine his requirements and establish the relative importance and criticality of each part of the system before choosing the most economical power-source systems to meet his needs. The various systems described offer phase changing, direct-current transformation, line-frequency and line-voltage transformation, isolation, and stabilization. Capability for short-time operation with stored-energy sources and long-time operation with engine-driven energy sources can also be included.

9- 1.2 Design Objectives

To design the power-source system for nuclear-reactor instrumentation and control and to achieve maximum reliability requires, at the outset, a thorough evaluation of the load characteristics. A designer of electronic systems is painfully aware of the risks in having instrumentation and control systems depend on plant auxiliary-power sources.

9-1 Introduction……………………………………………………………… 212

9-1.1 System Requirements…………………………………………. 212

9-1.2 Design Objectives……………………………………………… 212

9-2 Types of Power Supply…………………………………………….. 213

9-2.1 System Similarities……………………………………………. 213

9-2.2 Energy Storage Methods……………………………………… 213

9-3 Requirements for Power Supply……………………………………… 213

9-3.1 General System Categories………………………………….. 213

(a) Interruptible Systems…………………………………. 213

(b) Noninterruptible Systems…………………………….. 213

9-3.2 Load Characteristics and Causes of Trouble. . . 214

9-4 Components of Power-Supply Systems…………………………….. 214

9-4.1 Static Inverters…………………………………………………….. 214

9-4.2 Storage Batteries……………………………………………….. 216

9-4.3 Stored-Energy Eddy-Current Coupling………………….. 217

9-4.4 Engine-Driven Alternators………………………………….. 218

9-4.5 A-C and D-C Drive Motors…………………………………. 218

9-5 Design of Power-Supply System………………………………………. 219

9-5.1 Simple A-C/D-C System……………………………………… 219

9-5.2 Rectifier—Battery System…………………………………… 219

9-5.3 Rectifier—Battery—Static Inverter Systems. . . 219

(a) Basic Continuous-Inverter System………………….. 219

(b) Continuous-Inverter System with Direct

A-C Feed………………………………………………….. 219

(c) Continuous-Inverter System with

Electromechanical Transfer Switch…. 22u

(d) Continuous-Inverter System with High­Speed Transfer Switch 220

(e) Continuous-Inverter System with

Redundant Inverter and Transfer Switch. .221

9-5.4 Generator and Internal-Combustion-

Engine System…………………………………………………………. 222

9-5.5 Synchronous Motor-Generator—Flywheel-

Clutch—Internal-Combustion-Engine Systems…. 222

(a) Nonisolated System…………………………………….. 222

(b) Isolated System…………………………………………. 223

9-5.6 Induction Motor-Generator—Stored-Energy

Eddy-Current-Coupling—Internal-Combustion-

Engine System………………………………………………………… 223

9-5.7 Synchronous Motor-Generator—Stored-Energy

Eddy-Current-Coupling—Internal-Combustion-

Engine System…………………………………………………………… 224

9-5.8 Battery-Supported Motor-Generator Isolated

Systems…………………………………………………………………. 224

(a) Motor-Generator—Motor-Battery System. . 224

(b) Static Rectifier—Motor-Generator—

Battery System…………………………………………… 224

9-6 Conclusions……………………………………………………………….. 224

Bibliography………………………………………………………………….. 225

Complete independence from outside power sources would provide ideal integrity. The best power system for a particular application cannot be designed by just selecting available components to obtain complete power-source independence. The designer must take into account, in his effort to satisfy the overall design objectives economically, such aspects as the allowable outage time of the power source, allowable transfer time between normal and standby power sources, initial cost, maintenance expense, and operating cost The system that provides the desired reliability with the minimum cost is usually based on a compromise between many design considerations