中性子計測ハウジング取替工法の開発 [in Japanese] Development of In-core Monitor Housing Replacement Technology [in Japanese]
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Replacement technology of in-core monitor (ICM) housing of BWR was developed and applied in the operating Plant. This technology replaces stress corrosion cracking (SCC) susceptible existing ICM housing by new housing composed of SCC resistant material. Major procedure steps are removal of the existing ICM housing, welding and trimming of a new weld buildup, welding of a new ICM housing, and joint of a new ICM guide tube with the ICM housing using shape memory alloy couplings. Each procedure step is performed remotely with automated tools, which are installed from the reactor refueling floor, 26m down to the Reactor Pressure Vessel bottom, through core plate etc. After several years of development, this technology was applied to an ICM housing of Fukushima Daiich Unit #4 where a crack caused by SCC was found on October 1997. and site work was successfully completed in the end of January 1998.
- Transactions of the Atomic Energy Society of Japan
Transactions of the Atomic Energy Society of Japan 41(10), 1075-1083, 1999-10-30
Atomic Energy Society of Japan