NRA requests detailed anti-tsunami measures

January 23, 2013

NRA moves to require detailed measures against tsunami

Kyodo

http://www.japantimes.co.jp/news/2013/01/23/national/nra-moves-to-require-detailed-measures-against-tsunami/#.UQBHPPL1tEs

Nuclear body proposes requiring detailed anti-tsunami measures

http://mainichi.jp/english/english/newsselect/news/20130123p2g00m0dm025000c.html

TOKYO (Kyodo) -- Japan's Nuclear Regulation Authority on Tuesday proposed requiring utilities to implement detailed measures to protect their nuclear power plants from tsunami in a revision of current guidelines that stop short of doing so.

According to a draft of new safety standards following the 2011 Fukushima Daiichi plant disaster, each nuclear power plant should be designed to withstand the biggest tsunami that could hit a site.

In the draft, the NRA also warned that planners of new nuclear plants should be careful about older active faults, saying they must consider faults that have moved in the last 400,000 years, compared with the current guidelines that state in the past 120,000-130,000 years.

The requirements to be included in the new regulations, expected to come into force in July, are drawing attention because they could affect the resumption of the country's reactors. Only two reactors in Japan are currently operating amid safety concerns over the use of nuclear power.

The draft regulations, which were presented at a meeting with experts the same day, would oblige utilities to provide estimates regarding the biggest tsunami that could hit each plant and take measures to keep key facilities safe.

The NRA proposed requiring utilities to locate reactor buildings at elevations where even the biggest tsunami could not reach, or have such buildings protected by seawalls or other defenses.

Important facilities should be equipped with watertight doors in case sites are flooded, according to the draft.

Reinforcing facilities to withstand tsunami are one of the key lessons Japan learned from the Fukushima crisis, in which tsunami waves over 10 meters high flooded electrical equipment including backup generators, leading to the failure of reactor cooling systems due to loss of power.

Current regulations do not ask utilities to implement concrete safety measures.

In relation to measures to deal with the risk of earthquakes, the NRA plans to stipulate more clearly than in the existing guidelines on the quake resistance of nuclear plants that important facilities must not be built over active faults, according to the draft.