Fukushima Watch: Lawmakers Rank the Safety of Japan’s 50 Reactors

In a country as small, crowded and earthquake-prone as Japan, vetting nuclear reactors for safety is key — as the March 2011 accident at Fukushima Daiichi showed. Japan is the only economy, besides Taiwan, that has so many nuclear plants in quake zones.

Japan Atomic Power Co.’s Tsuruga nuclear power plant.

So which of the country’s 50 reactors are safest to operate?

A bipartisan group of 10 lawmakers– all of whom support reducing Japan’s reliance on nuclear power– looked into that question. They ranked the reactors by nine criteria, including reactor age and type, accident records, average operating rates, quake vulnerability and proximity to large population centers.

They found the 10 safest reactors are run by three utilities — Kyushu Electric Power Co. (6), Shikoku Electric Power Co. (2) and Hokkaido Electric Power Co. (2). They are the smallest of Japan’s 10 utilities, and their plants are relatively new, and located far from large cities.

The worst performer is Japan Atomic Power Co.’s Tsuruga No. 1 reactor, which was recently found to have an active fault running right underneath.

Tsuruga is followed by Oi Nos. 1-2, Mihama Nos. 1-3, and Hamaoka Nos. 3-5. Of the worst 10, five are owned by Kansai Electric Power Co., and three by Chubu Electric Power Co., the nation’s second and third largest utilities. The still-operational reactors of Tokyo Electric Power Co., which runs Fukushima Daiichi, came in toward the middle of the rankings. But all Tepco’s reactors were on a second list of facilities the lawmakers thought should be scrapped, based on the risks of future earthquakes or damage done by recent quakes. Tepco’s remaining reactors have all suffered damage from earthquakes in 2007 and 2011.

The bottom 10 ranking reactors are all 30 years old or more, except for the three Hamaoka reactors, which are newer but sitting in a region with a high risk of being hit by a Magnitude 8 earthquake.

The list is still a preliminary, the lawmakers’ group says, since it has yet to incorporate other important risk factors such as the strength of tsunami barriers and the availability of emergency-operation facilities.

The rating should also take into account plant layout and what’s around the facilities, argues Ikuko Tanioka, an upper house member of the ruling Democratic Party of Japan. “Many of them have no open space around them to host large Self-Defense Force contingents,” she said. “Many also stand in snowy regions, with access easily blocked in winter.”

The Self-Defense Forces, Japan’s equivalent to a military, played a big role in helping control last year’s accident at Fukushima Daiichi, and evacuate residents in the surrounding areas.

Another possible hazard is multiple reactors at the same location, says Masaru Kaneko, a Keio University professor and expert on the economics of nuclear power, who was invited by the lawmakers to comment on the rankings. Most Japanese plants have three, four, or even up to seven reactors in one place. That means an accident at one reactor could easily affect the operations of other units, as happened at Fukushima Daiichi. “No more than two reactors should be allowed to restart at any one plant,” Mr. Kaneko said.

But scrapping reactors is costly. According to the Ministry of Economy, Trade and Industry, if Japan abandons nuclear power now, utilities would need to register ¥4.4 trillion in one-off costs for decommissioning and asset write-offs. They will also face ¥3.1 trillion in additional fossil-fuel costs every year.

As of the end of March, the nation’s 10 utilities had a combined net worth of only ¥5.7 trillion. An immediate exit from nuclear power would leave four of them insolvent — Tepco, Tohoku Electric Power Co., Hokkaido Electric and Japan Atomic Power, METI said.



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