Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

A. Chambon*, R. Luís, E. Klinkby, Y. Nietiadi, D. Rechena, B. Gonçalves, M. Jessen, S.B. Korsholm, A.W. Larsen, B. Lauritzen, J. Rasmussen, M. Salewski, M. Fabbri, C. Morillo

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

Abstract

The ITER Collective Thomson Scattering (CTS) system will be the main diagnostic responsible for measuring the velocity distribution function of fusion-born alpha particles in the plasma. As the CTS diagnostic is integrated in the equatorial port plug 12 (drawer 3), with direct apertures to the port interspace where maintenance hands-on operation will be carried out, it is essential to assess the shutdown dose rates (SDDR) in these maintenance areas. In this work, the D1S-UNED3.1.4 Monte-Carlo transport code, based on the implementation of the direct-one-step methodology in MCNP5 v1.60, was used to estimate the dose rate level 12 days (106 s) after shutdown in the port interspace. The results show that the CTS system does not contribute significantly to the SDDR in the area where hands-on maintenance is foreseen with contribution to dose rates less than 1 µSv/h. This is consistent with previous estimates, although with the most recent model of the CTS design there is a slight increase of the SDDR values. This deviation can be attributed to design changes and improved shielding modelling and/or most importantly, to statistical fluctuations of the D1S simulations. From a neutronics point of view, the increase in the SDDR falls within the range of the statistical fluctuations, and the design is still compliant with the radiation safety ALARA principle aiming at minimizing radiation doses, and there is no requirement for further design optimizations.
Original languageEnglish
Article numberC12001
JournalJournal of Instrumentation
Volume16
Issue number12
Number of pages10
ISSN1748-0221
DOIs
Publication statusPublished - 2021
Event4th European Conference on Plasma Diagnostics - Online
Duration: 7 Jun 202111 Jun 2021
Conference number: 4

Conference

Conference4th European Conference on Plasma Diagnostics
Number4
LocationOnline
Period07/06/202111/06/2021

Keywords

  • Radiation calculations
  • Simulation methods and programs

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