Development of Detritiation System using Microbial Activity

Research Project

Project/Area Number	08558054
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	展開研究
Research Field	Nuclear fusion studies
Research Institution	KYUSHU UNIVERSITY
Principal Investigator	MOMOSHIMA Noriyuki Kyushu Univ.Fac.Sci., Associate Prof., 理学部, 助教授 (80128107)
Co-Investigator(Kenkyū-buntansha)	MATSUI Kiyoaki Kyushu Matsushita Co., Senear Researcher, 主任研究員 MATSUOKA Nobuaki Kyushu Envir.Eval.Assoc., Senear Researcher, 主任研究員 OKAI Tomio Kyushu Univ.Fac.Eng., Assistant Prof., 工学部, 講師 (50150488)
Project Period (FY)	1996 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥6,300,000 (Direct Cost: ¥6,300,000) Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000) Fiscal Year 1996: ¥4,200,000 (Direct Cost: ¥4,200,000)
Keywords	Detritiation system / Tritium / Oxidation / Tritium gas / Silicon tube / Microbial activity / 多孔質担体 / 微生物固定 / フィルター
Research Abstract	Hugh amounts of tritium are planning to use in nuclear fusion reactors in future. To keep radiological safety for the operation of nuclear reactors, detritiation system is necessary. In this study a new detritiation system, which uses microbial activity, is developed. Microorganism that can oxidize HT to HTO was extracted from general soil by repeated culture. The yellow color organism was capable to keeping in a refrigerator for a long time. Oxidation activities of the organism in development and stationary stages were examined using hydrogen molecule and effective oxidation activities were confirmed in both stages. Oxidation activity was confirmed by applying tritium gas (tritium molecule) to the organism. For detritiation system, separation of gas phase that containing tritium gas from liquid phase that containing microorganism is preferable to avoid cross contamination. We, then, developed a system that uses tube such as silicon for separation of gas phase and liquid phase. Tritium … More gas in the gas phase diffuses to liquid phase through tubes and oxidized to HTO by microbial activity in the liquid phase. Teflon, polyethylene, and silicon were examined and silicon showed highest detritiation rate. Surface area and thickness of silicon tube was examined how the detritiation rate changes. The increase in surface area increased detritiation rate. The thickness of tube did not influence on the detritiation rate, suggesting dissolution of tritium gas to silicon determined the rate. Flow rate of gas phase affected to the detritiation rate ; higher flow rate showed more effective detritiation rate, but saturation of the detritiation rate was observed above a certain flow rate. Turbulence transfer of tritium molecule to the surface of the silicon tube increased with increase of flow rate of gas phase. In nuclear fusion reactors, high concentration of tritium gas will be treated with a conventional detritiation system, which uses metal catalyst at high temperature. The present system is useful for the condition that tritium gas was released to high humid air and wide space like a room of building. The present system can be operated at room temperature and needs small electric power that can drive an air pump. Less