Decommssioning of Japan's Hamaoka NPP continues

5 February 2016

Japan's Nuclear Regulation Authority (NRA) has given approval for Chubu Electric Power Company to decommission equipment at units 1 and 2 of its Hamaoka NPP in Shizuoka Prefecture - the second phase of its decommissioning plan.

Chubu Electric began decommissioning the plant in 2009, with the aim of completely the work by fiscal 2036. Chubu Electric plans to dismantle exhaust stacks, steam piping, the turbines and the main condensers by fiscal 2022, and to decontaminate the reactor pressure vessels. The company estimates that this phase will yield about 5,000t of low-level radioactive waste, but has no firm plan for its disposal and tentatively proposes keeping some of the waste in buildings at the plant.

The utility submitted a decommissioning plan for Hamaoka 1 and 2 in June 2009, which was revised the following September. The work is divided into four stages: the first stage was preparatory work for dismantling; the second stage includes dismantling and removal of equipment surrounding the reactors; the third stage is to dismantle the reactors; and the fourth covers demolition of buildings at both units. The plan was approved by the ministry of economy, trade and industry in November 2009. Chubu Electric completed the first stage in March 2015 and then applied to the NRA for permission to start phase two.

Hamaoka 1 (540MWe) and 2 (840MWe) are boiling water reactors, which began operation in 1973 and 1978, respectively. Chubu decided to close both in January 2009 because they required expensive modifications to meet seismic standards imposed after the July 2007 Niigata Chuetsu offshore earthquake. Following Fukushima, Chubu complied with a request from then-prime minister Naoto Kan to close Hamaoka 4 and 5 were shut down. Unit 3 was already offline for regular inspections. The enhanced safety measures are expected to be completed in September 2016 for unit 4 and in September 2017 for unit 3. Chubu is exploring necessary measures for unit 5.

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