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Japanese nuclear regulator approves restart of tsunami-hit Onagawa reactor

27 November 2019

According to the Kyodo news agency, a nuclear reactor in north-eastern Japan that was damaged by the 2011 earthquake-tsunami disaster and subsequently shut down has finally received the Japanese Nuclear Regulation Authority’s approval to resume operations.

Onagawa NPP - Image: Wikimedia CC
Onagawa NPP - Image: Wikimedia CC

The No. 2 reactor of Tohoku Electric Power Co.’s Onagawa plant in Miyagi Prefecture received the green light from the NRA after the addition of anti-disaster measures including a large sea wall that is nearing completion.

The Onagawa plant was the closest nuclear plant to the epicentre of the magnitude 9.0 quake that struck northeastern Japan on March 11, 2011, and heavy shaking triggered an automatic shutdown of its three reactors.

While the No. 2 reactor building suffered flooding from the subsequent 13-metre tsunami and lost up to 70% of its earthquake-resistance strength, the plant’s emergency cooling system remained intact and did not suffer a meltdown, unlike at Fukushima Dai-ichi’s 1, 2 and 3 reactors operated by Tokyo Electric Power Co. (Tepco), 165 kilometres to the south.

It is only the second nuclear reactor damaged by the March 2011 disaster to clear the NRA’s new safety standards after the Tokai No. 2 power station in Ibaraki Prefecture.

As well as the sea wall, Onagawa still needs to complete other anti-disaster measures as well as receive local consent to restart, meaning it will almost certainly remain offline until after 2020.

Tohoku Electric expects to spend ¥340 billion ($3.1 billion) on the measures, primarily the 800-metre long wall reaching 29 metres above sea level along the perimeter facing the Pacific Ocean to guard against a tsunami up to 23 metres high.

Costs for enhanced safety measures have ballooned and are expected to further swell with the construction of facilities to be used in the event of a terrorist attack, also required under the new safety standards, Kyodo says.

Tohoku Electric applied for a safety screening for the No. 2 reactor in December 2013, and its restart would save the utility ¥35 billion annually in fuel costs. The No. 1 reactor is scheduled to be decommissioned, while the utility is considering whether to seek approval to restart the No. 3 reactor.

The Onagawa No. 2 reactor may become the first boiling water reactor — the same type used at the Fukushima plant — to resume operations after the disaster, which claimed nearly 16,000 lives and left more than 2,500 missing. In Onagawa, more than 800 were killed or went missing.

Other boiling water reactors at Tepco’s Kashiwazaki-Kariwa plant in Niigata Prefecture and the Tokai No. 2 plant of Japan Atomic Power Co. already have NRA approval to resume operations, but have yet to obtain local consent.

The Fukushima disaster led to the shutdown of the country’s 54 operational reactors, which once provided nearly a third of Japan’s electricity. All those considered for restart had to be relicensed under new standards after the disaster highlighted operational and regulatory failings.

Nine reactors have been restarted, all of them pressurised water reactors located in the south of the country. Because of Fukushima, a stigma still hangs over use of the older BWR technology.

Reuters estimates that 21 of Japan’s reactors will be decommissioned, a further 11 are shut with any restart unlikely, six are shut with restart uncertain, and another seven are shut with restart likely at some point in the future.

While the approval will be a boost for Japan’s embattled nuclear industry, the sector will still miss a government target of providing at least a fifth of the country’s electricity by 2030, an analysis by Reuters showed last year.

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