Shutdown dose rate assessment of the interspace components of wide angle viewing system diagnostic for ITER

Abstract

Shutdown dose rate (SDDR) calculations have been performed to give support to the design of the Interspace (IS) VIS/IR WAVS diagnostic components of the Equatorial Port 12 (EP12), in the framework of the F4E-FPA-407 SG04 project. The Vis/IR WAVS comprises the viewing systems in four Equatorial Ports: 3, 9, 12 and 17, reminding that the present results are relative to the EP12 specifically. The Vis/IR WAVS is an optical diagnostic aimed at monitoring in visible and infrared radiation the ITER plasma facing components for machine protection.This paper describes the methodology used and shows the results obtained. The objective of the assessment is to evaluate whether the design meets the ALARA criteria in the IS area. In this work, once the materials have been selected to contribute as less as possible to the activation, the main criterion is that the contribution of all diagnostics installed in the port should not overcome the target of the biological dose rate of 100 μSv/h in the IS area after 106s of decay time.The main conclusion of the analysis is that the contribution of the VIS/IR WAVS IS components to the SDDR meets with the ALARA criterion in the IS. The contribution of the VIS/IR WAVS IS components to the SDDR in the IS, concerning the contribution of the whole ITER model, is about 9.6% in the left corridor and 5.5% in the right corridor. Besides, the percentage of contribution of the SS316L structure with respect to the total SDDR induced by the IS VIS/IR WAVS components is 99.3% in the left corridor and 99.5% in the right corridor. However, it has to be taken into account that these values have been obtained using a local model, therefore these values will be lower than the realistic values. Therefore, these values should be taken only as relative values.