MHI Begins Installation of Radioactive Waste Storage Facility Equipment

TEPCO is currently taking various measures towards restoration after the accident at the Fukushima Daiichi Nuclear Power Station. One of the most critical issues is the processing of water containing radioactive substances accumulated within the station's Unit 1 to 4 buildings. At present, reactors are being cooled by circulating water that is treated by radioactive substance removal and desalination processes. The storage facility to be constructed will stably store radioactive sludge, of slurry consistency, generated during coagulated settling within the decontamination apparatus in the radioactive substance removal process.

The sludge storage facility will consist of a number of facilities and systems, including sludge storage tanks to be installed in a cell room surrounded by 1 meter (m) thick concrete walls, a system to process off-gas from the sludge storage tanks, a ventilation and air-conditioning system, a control system and utility facilities. The 13.5m-long, 3.2m-diameter cylindrically shaped sludge storage tanks will be made of 25 millimeter thick iron. Eight tanks, including one for back up, with sludge storage capacities of up to 90 cubic meters each, will be horizontally installed in the facility. The tanks will also function to agitate waste sludge and scavenge hydrogen.

In delivering the storage facility, MHI will fully utilize its comprehensive technological expertise in system design and construction methods. This pool of knowledge draws upon the company's experience in delivering storage tanks for highly radiated waste liquid to the Tokai and Rokkasho reprocessing plants (respectively in Ibaraki and Aomori prefectures) and on its knowhow accumulated through construction of many plants both within and outside Japan.

MHI has been supporting recovery efforts at the Fukushima Daiichi Nuclear Power Station in various ways, including conversion of a "Mega-Float" for pooling of moderately radiated accumulated water and the provision of forklift truck-based special vehicles equipped with a radiation-shielded cabin to handle rubble in the accident site. Going forward the company will continue its full engagement to support restoration operations.