JAERI nuclear analyses for IFMIF

Full text: In JAEA, which is a new name of JAERI, a shielding analysis of the IFMIF target room concrete wall and an analysis of radioactive erosion and corrosion products in the IFMIF lithium loop have been carried out for IFMIF. When replacing heavy concrete at the front wall to normal concrete, neutron doses become ∼ 10 (at 2m depth) to 100 (4m depth) times higher. In this case, introduction of the steel layer at the surface of the wall can compensate the degradation. On the other hand, introduction of the water channels in the surface of the wall is not effective to enhance the shielding performance. An analysis of radioactive erosion and corrosion products was conducted to estimate the radioactive corrosion products with a design code ACT-4 developed in JAERI, the activation cross sections based on the FENDL library and the IEAF-2001 library. The result says the concentration of the corrosion in lithium is not very large compared with that of 7Be. However, the behavior of the nuclides such as accumulation and detachment on material has not been clarified yet. When the dose rate around the lithium loop was estimated under the condition of 100% plate-out, the value was beyond the acceptable level for the hands-on maintenance near the loop soon after the operation stop. It means that a very efficient cold trap is required so that the 90% activity in the lithium loop is removed. (author)