Occupational radiation exposure during inspection and maintenance of the ITER water cooling system. A comparison between two working strategies

The international thermonuclear experimental reactor water cooling system ( ITER WCS) is divided into 20 loops with the aim to reduce the consequences of a loss of coolant accident (LOCA). This makes the ITER WCS a very compli cated system with many components requiring periodical inspection and maint enance. The main radiological concern for the staff involved in such activi ties is due to the activated corrosion products (ACPs) generated by corrosi on of the inner wall of the piping under the neutron flux. In the present s tudy the collective dose due to the ACP for one loop of the ITER WCS is ass essed. Two different maintenance and inspection (M/I) approaches (or workin g strategies) for the ITER WCS components are to be considered. The first o ne is usually applied in American and European designs of pressurised water reactors (PWRs) that have cooling loops similar to those envisaged in ITER . The other one is the strategy proposed by the ITER WCS designers that tak es into account the actual plant layout and technology. Both strategies hav e been implemented in the occupational radiation exposure (ORE) assessment process and two results have been obtained. The similarity is then performe d pointing out the differences between the two approaches, trying to indica te what is the best one from the ORE point of view. (C) 2000 Elsevier Scien ce B.V. All rights reserved.