Shielding conceptual designs of ITER TCP ports to protect electronics

Abstract

Critical electronics of ITER Tokamak, hosted in the shielded corners (SC) of the Tokamak Building (B11), must operate under acceptable neutronic flux conditions (≤10 n·cm−2·s − 1) to minimize single event effects. During machine operation and at lower level (B1), both the Torus Cryopumps (TCP) ports location within B11 and their pumping efficiency constraints are factors contributing to the radiation environment in the SC. Although previous studies have addressed the transmission of radiation out the vessel of TCP ports, none of them have assessed the impact of such radiation beyond the Port Cell. In this work, different TCP shielding configurations were evaluated at B1 level of B11 due to plasma neutrons emerging from the six TCP ports only. MCNP and dedicated computational tools were used to perform the radiation transport calculations. Albeit being a partial study, the examination of the compatibility between the TCP plasma neutron flux and the electronics limit in the SC has been addressed, while considering the combined effect of the shielding design and the building walls, lintels and doors in the results. We present a combined shielding case that reduces the neutron flux to a range of 1.3–9.3 n·cm−2·s − 1 depending on the location, which is compatible with the limit while respecting pumping efficiency and assembly difficulty constraints.