THE OBJECTIVE OF THIS RESEARCH IS THE IDENTIFICATION OF THE DESIGN AND CONSTRUCTION RULES WHICH SHOULD REASONABLY BE BROUGHT INTO OPERATION FOR THE PROJECTED FAST BREEDER REACTORS (FBRS) IN ORDER TO FACILITATE THEIR DISMANTLING.
A POOL-TYPE SODIUM-COOLED FBR WITH A GENERATING POWER LARGER THAN 1000 MWE WILL BE TAKEN AS A REFERENCE FOR THIS STUDY. PRIORITY WILL BE GIVEN TO DESIGN FEATURES INVOLVING LOW EQUIPMENT COSTS AND LITTLE DEVELOPMENTS. OTHER FEATURES WILL ONLY BE MENTIONED.
Calculations have been devised taking into account the activation and contamination of SPX1/SPX2 fast breeder reactor (FBR) components. The decay time influence has been studied for some representative structures of the reactor block. The main radionuclides are iron-55 and cobalt-60 for short time decay (activation), nickel-63 and niobium-94 for long time decay (activation), and caesium-137 and sodium-22 for contamination. From these elements, the phases of final shutdown and decommissioning to be followed according to the different L'Agence Internationale de l'Energie Atomique (AIEA) levels have been estimated. The delay time has been defined from the known technical criteria. The analysis of different scenarios and the activity calculations permit precise decisions about the different types of measures to facilitate decommissioning to be made.
B.1. COMPILATION AND ANALYSIS OF THE DESIGN FEATURES OF A FBR (> 1000 MWE) WITH REGARD TO DECOMMISSIONING (MAIN DIMENSIONS AND QUANTITIES, NATURE AND LOCALISATION OF CONTAMINATION AND ACTIVATION, CAPACITIES OF AUXILIARY SYSTEMS, ETC.)
B.2. IDENTIFICATION OF THE MAIN FEATURES DETERMINANT TO DECOMMISSIONING : CALCULATION OF ACTIVATION AND DOSE RATES OF MAJOR COMPONENTS, ASSESSMENT OF PROBLEMS POSED BY CONTAMINATION, ETC.
B.3. STUDY OF VARIOUS STAGES OF DISMANTLING, INCLUDING ASSESSMENT OF REMOTE DISMANTLING AND DEFERRED DISMANTLING.
B.4. IDENTIFICATION AND EVALUATION OF COST-EFFECTIVE DESIGN FEATURES FACILITATING DECOMMISSIONING, CONSIDERING LOW-COBALT STEELS, COATINGS; PRIMARY CIRCUIT DRAINING AND RINSING, DECONTAMINATION OF REACTOR INTERNALS, REMOTE DISMANTLING, ETC.