The Tohoku Electric Power Company has submitted plans for decommissioning the Onagawa Unit 1 reactor with Japan’s Nuclear Regulation Authority, making it the tenth reactor in the country since the Great East Japan Earthquake of March 2011 to be scheduled for closure.
The company had already said it would decommission the boiling water reactor, stating that there was not enough space in the containment vessel in the small 524MWe plant to include new safety equipment required after the Fukushima Dai-ichi triple reactor meltdown that occurred as the result of the devastating earthquake’s subsequent tsunami.
According to Nuclear Engineering International, the containment vessel would have to include fire extinguishing equipment, power supply equipment and a separate water injection pump system. A victim of size, the plant would be unprofitable if the upgrades were unavoidable.
Tohoku Electric operates four nuclear power plants including Onagawa 2 and 3 at 825MWe each, which first began producing power in 1995 and 2002, respectively. In Aomori Prefecture, the Higashidori plant operated by Tohoku began operations in 2005. Onagawa 1, meanwhile, entered into commercial operations status in June 1984.
Decommissioning is expected to take 34 years, including the removal of 60 metric tons of high level radioactive waste, 740 metric tons of low-level waste and 5,340 metric tons of very low level waste. The first step, however, will be the removal of 821 used fuel assemblies, which will be transferred to the Onagawa 3 storage pool.
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