Study of decontamination and maintenance for vehicle manipulator of ITER blanket remote handling system

Abstract

Abstract The ITER blanket remote handling system (BRHS) will be operated in the ITER vacuum vessel (VV) after plasma operation to exchange the blanket first walls (FWs) and shield blocks (SBs), which can weigh up to 4.5 t and be larger than 1.5 m. The most important operation for the BRHS is the two-year maintenance campaign in which all 440 FWs must be replaced. The in-vessel components will have been activated by neutrons produced by the D-T reaction, with the total dose estimated to be 5 MGy. Moreover, activated dust will have accumulated in the VV and will contaminate the BRHS. The BRHS must first be transported to the red zone of the hot cell facility where it will be decontaminated remotely. The BRHS will then be transported to the hands-on area to be decontaminated manually and undergo maintenance. The ITER Organization has defined the dose rate criteria in the hands-on area as 100 μSv/h, thus, decontamination and maintenance activities must be performed in compliance with these criteria. In this paper, the parts that will require replacement in the two-year maintenance campaign are estimated based on the results of past irradiation experiments studies; areas of the BRHS that could not be decontaminated remotely are specified; and the dose rate to workers standing near the BRHS are calculated by using Monte Carlo N–Particle Transport Code analysis to establish the BRHS maintenance plan.