Accessibility evaluation of the IFMIF liquid lithium loop considering activated erosion/corrosion materials deposition

Nakamura, Hiroo; Takemura, Morio*; Yamauchi, Michinori*; Fischer, U.*; Ida, Mizuho*; Mori, Seiji*; Nishitani, Takeo; Simakov, S.*; Sugimoto, Masayoshi

In the IFMIF, activated erosion/corrosion materials of Li target back wall deposits on a surface of the Li loop. Therefore, accessibility during maintenance of the Li loop pipings will depend on the activation level of the deposition materials. This paper evaluates effect of target activation on the accessibility of the Li loop pipings. Activation level is calculated by the ACT-4 code. High energy cross section above 15 MeV is introduced using IEAF-2001 data. In this calculation, target material is stainless steel 316. Area of the erosion/corrosion in the back wall is 100 cm. The erosion/corrosion rate is 1 micron/y. Dose rate around the Li loop after one year IFMIF operation is evaluated assuming 1% deposition of the erosion/corrosion materials and uniform deposition on surface area of 33 m. Permissible level for hands-on maintenance is 10 microSv/hr. As the results, after 1 week from shutdown, close maintenance work 8 cm to the Li loop is possible. Also, after 1 month, hands-on maintenance becomes possible.