Concentration of reactors involves "unique" risks

 December 19, 2014

EDITORIAL: Risks posed by nuclear reactor clusters left unaddressed

http://ajw.asahi.com/article/views/editorial/AJ201412190028

Simultaneous accidents at multiple nuclear reactors could jeopardize the survival of the nation.

This is a grim reality we faced during the harrowing nuclear crisis that broke out in 2011 at the Fukushima No. 1 nuclear power plant.

But both electric utilities and the Nuclear Regulation Authority (NRA) appear reluctant to face up to the risk of multiple nuclear accidents occurring simultaneously.

In a draft report on its safety reviews of the No. 3 and No. 4 reactors at Kansai Electric Power Co.’s Takahama nuclear plant in Fukui Prefecture, the NRA said the two reactors had cleared the new safety standards.

That means the Takahama plant became the second nuclear power facility to receive the virtual go-ahead to resume operations under the tougher safety requirements introduced after the Fukushima nuclear disaster. Previously, the No. 1 and No. 2 reactors at Kyushu Electric Power Co.’s Sendai plant in Kagoshima Prefecture had passed the NRA’s safety screenings in line with the stricter regulations.

Unlike the Sendai plant, however, the reactors at the Takahama plant are located near many other reactors.

Besides the No. 3 and the No. 4 reactors, the Takahama plant has two other reactors--the No. 1 and the No. 2 units. There are also four reactors at Kansai Electric Power’s Oi nuclear power plant, which is located about 15 kilometers from the Takahama complex.

In addition, there are five other reactors about 50 km from the Takahama plant--three at the same utility’s Mihama nuclear plant and two at Japan Atomic Power Co.’s Tsuruga plant. A total of 13 reactors are concentrated in the area.

None of the 13 reactors is set to be decommissioned. Kansai Electric Power has applied for the NRA’s safety screenings of the No. 3 and the No. 4 reactors at the Oi nuclear plant. The company has also indicated its intention to submit applications for the No. 1 and the No. 2 reactors at the Takahama plant.

Shunichi Tanaka, chairman of the NRA, has acknowledged the problem of such a cluster of reactors. The risk “may have to be given sufficient consideration when a new reactor is built,” he said.

But the NRA’s current safety screenings only assess whether individual reactors meet the safety standards required to prepare for natural disasters and severe accidents.

The nuclear regulators do not assess the safety risks stemming from the geographic proximity between the Nos. 3 and 4 reactors at the Takahama plant and the Nos. 3 and 4 units at the Oi plant.

Under the current safety screening system, any number of offline reactors can be restarted as long as they clear the safety standards individually. As a result, a group of reactors located in close proximity could be brought back online in a piecemeal process.

As the NRA itself has admitted, clearing the new tougher safety standards does not mean zero accident risk.

If a major natural disaster, such as a massive earthquake, triggers multiple reactor accidents within a narrow area, efforts to deal with the accident at one reactor could be seriously hampered by radioactive materials released from other nearby reactors. Bringing the situation under control would be extremely difficult.

Responding to such multiple nuclear accidents would be a far more formidable challenge than dealing with a single accident. The abilities of the companies that operate the reactors as well as society as a whole would be severely tested.

Few other countries in the world have so many clusters of nuclear reactors located within a relatively narrow area.

Such a setup requires safety screenings that take into consideration the unique risks involved in concentrations of reactors.

Serious debate is needed on the tolerance level for such a concentration of safety risks in a relatively narrow area.

If idled reactors in such clusters are to be restarted, the public deserves a more detailed and convincing explanation about how to deal with the risks.

How should the risks of concentrated reactor locations be considered?

If this is a question that is too important and complicated to be left to electric utilities and the NRA, the government should step up to the plate and tackle the challenge head-on.

--The Asahi Shimbun, Dec. 19