7.1. Drive Mechanisms Instrumentation

The position of the piston in the Drive Mechanism gives the position of the neutron absorber in the core. The length of the piston is 300 mm and the length of the cylindrical cover is 1850 mm. The method used to measure the piston position is called Magnetically Variable Inductance.

The piston made from magnetic Stainless Steel is moving inside the cylinder covered with an electrical coil with high concentration of rings in one end and decreasing to the other. All other pieces of the Drive Mechanism are non-magnetic. A fine measurement of the inductance gives a measurement of the piston position and consequently of absorber position. The resolution measured was better than 1%.

The test were made at room temperature and non immersed in water and the inductance was measured. Interference and very low frequencies are a challenging situation and due to that, lab instruments of high complexity and cost were used. The design of a specifically designed instrument to measure inductance was finished and a prototype to operate at CAREM conditions will be tested in the “warm” and “hot” test mentioned in Section 6. of this work.

7.2. Reactor Protection System (RPS)

Description

The RPS is based in solid state intelligent processing units and hard-wired multiplexed voting and protective logic units. It has four redundant, independent channels, whose main features are:

• High reliability and availability as a result of design criteria and technology

• Fault-tolerance with on line auto-verification routines and auto-announcing capability

• Compactness and robustness

• High simplicity

Current developments

The current developments are originated from the Safety Requirement Specifications of the RPS.

Trip Unit:

The trip unit performs the data acquisition of the safety variables and compares them against the Safety System Settings to initiate the protective actions in case of anticipated operational occurrences or accident conditions. The development of the Trip Unit is subdivided in the following stages:

• Software Requirements Specifications & prototype

• Software design, code and implementation

• Hardware Requirements Specifications & prototype

• Hardware design and implementation

• Integration Requirements Specifications

• Integration Hardware/Software

• Validation

• Installation & Commissioning

• Operation & Maintenance

At present, the status of the development is at design stage in both hardware and software

Voting and Protective Logic Unit

The voting and protective logic unit performs the voting of

the redundant safety trip signals coming from the Trip Units in a logic arrangement of 2 out of 4 and then, according to the logic relations of the trip signals and initiation criteria, triggers the protective actions.

The development of the Trip Unit is subdivided in the following stages:

• Hardware Requirements Specifications & prototype

• Hardware Requirements Specifications

• Hardware design and implementation

Description

The highly automated digital Supervision & Control System, has an architecture of 5-level hierarchy with distributed processing and modem control technology It is conformed by different types of processing units

• Supervision Units (SU)

• Information Units (IU)

• Control Units (CU)

• Field Units (FU)

The Supervision & Control System is totally independent of the RPS High system reliability and availability are achieved by the use of redundancy and fault-tolerance in communications and processing unit

Operator interface is based on digital visual display units for safety, alarms, logics, processes and documentation presentation in the reactor main control room and others supervision and control centers Modem technologies as touch-screens, track-balls, custom keyboards, etc are used

Current Developments

The Supervision & Control System includes the development of a Control Operating System that implements all the low level functions as

Real-Time Data Base Communication System Control Functions Svstcm Management

This Control Operating System acts as a software platform on which the Supervision & Control System application is built on 1 he development process is divided in the following phases

Software Requirements Specifications & Prototype Software Design Specifications

Software Coding, Implementation & Integration Validation & Verification

Instalation <S_ Operation

The Ward Si Mcllor Methodology is applied in every phase of the development process At present, the status of the development is at Coding phase

8. Fuel Elements

The activities in this subject are being carried out by CNEA itself At present the detailed engineering for the CAREM 25 Fuel Elements and absorbers are under execution

Development of equipment for components and FE manufacturing.

The following tasks have already been earned out

• Development and construction of equipment for caps welding by TIG method

• Development and construction of dies for stamping and cutting elastic spacers components

• Development and construction of FE assembly and final control boards

• Construction of different manufactunng and metrological control devices for FE manufacturing

• Prototype of elastic spacer for the FE

• Dummy FE to define handling tools

Current developments

The following tests are under definition stages

• Elastic spacers mechanical and stress tests

• Fuel element seismic behaviour test

• Thermalhydrauhc behaviour in a low pressure loop

• Thermalhydrauhc behaviour in a high pressure loop

References

/1/ Dcnimns M. Метопа desenptiva del CAPCN, INVAP 0758 5302 2IASS 315 10 (1994)

/2/ Carnca, Pablo, Analisis de Analogies entre el reactor CAREM-25 у el CAPCN, INVAP, 0758-8700-2TAJN-003-10 (1994) /3/ Masnera. Nestor, Ensayos Dinamicos previstos para el CAPCN, INVAP 0758 8680 31AIN 012 1 0 (1994)

/4/ Camca, P & Balina J, Plan de Ensayos de FCC, Parte I, caractenz instalacion, INVAP 0758-8720-31 AIN-001-1A (1994)

/5/ Carrica P &. Balina J. Plan de Ensayos de FCC, Parte II, Ensayos Preliminares, INVAP 0758-8720-3IAIN-002-1AO(1994)

/6/ Carnca. P & Balina J, Plan de Ensayos de FCC, Parte III, Ensayos Finales, INVAP 0758-8720-31 AlN-003-10 (1994)

ПІ RA-8 Preliminary Safety Report,

/9/CONDOR 1 3, Villanno Eduardo INVAP (1995)

/10/ Strawbidgc and Barry Cnticality Calculations for Uniform Water Moderated Lattices, NSE, 23, 58 (1965)

/11/ Raslog. Muligroup Methods in Thermal Reactors Lattice Calculation, Lecture, Bogota, Colombia

/12/ Macdcr and Wydlcr, International Comparison Calculations for a BWR Lattice with Adjacent Gadolinium Pins, EIR-Bericht 532, NEACRP-L-271 (1984)

/13/ Arkuszcwsky, MCNP Analysis of the Nine-Cell LWR Gadolinium Benchmark, PSI-Beritch 13 (Aug 1988)

/14/ Szatmary, Experimental Investigation of the Physical Properties of WWER-Type Uranium Water Lattices, Final Report of TIC. Vol I, Akademiai Kiado, Budapest (1985)