Nuclear power plant closed in Japan to make it more tsunami-proof

Temporary closure knocks Chubu Electrical's share price as company plans protective wall 12 metres high and nearly 1.6km long after Fukushima disaster.

Chubu Electric Power's Hamaoka nuclear power station in Omaezaki, Japan, is being temporarily closed down.

A Japanese power company has agreed to close a nuclear power plant amid concern that it remains vulnerable to a tsunami of the kind that caused the Fukushima crisis.

The decision to temporarily close the Hamaoka plant, about 200 kilometres west of Tokyo, came after a request from Japan's prime minister, Naoto Kan, to allow safety improvements to be made to make the coastal facility more resistant to seismic activity, including tsunami waves.

Its operator, Chubu Electrical Power Company, has drawn up plans in recent weeks to build a protective sea wall over the next two to three years, 12 metres high and nearly 1.6km long.

The company has also proposed installing more backup generators and making reactor buildings more watertight. The crisis at the Fukushima plant, where engineers are still working to achieve a stable "cold shutdown" of reactors, developed when emergency power supplies were disabled by tsunami waters.

Seismologists have warned that over the next three decades there is a high probability of an earthquake of 8.0 magnitude or greater hitting the region that contains the Hamaoka plant.

Mr Kan's call on Friday for the facility to be closed came after a government evaluation of earthquake and tsunami resistance at Japan's 54 nuclear reactors.

Two active reactors are being shut down, while the restarting of a third that was undergoing maintenance will be delayed. The facility also includes two reactors dating back to the 1970s that were shut down permanently two years ago.

Current sandwalls at the plant are thought able to protect against a tsunami up to eight metres high, little more than half the height of the waves that struck the coast where the Fukushima plant is located.

The Hamaoka complex generates more than one tenth of Chubu's power supplies, and the company's share price fell heavily yesterday as a result of Mr Kan's earlier call for the plant to be closed.

The company's president, Akihisa Mizuno, told reporters: "By halting the Hamaoka nuclear plant, we are causing great short-term trouble to not only those in the plant area but also many others including our customers and our shareholders.

"But firmly implementing measures to strengthen safety would become the cornerstone to continue safe and stable nuclear power in the long-term and, in the end, lead to the benefit of our customers."

Yesterday analysts yesterday warned that companies may consider relocating factories outside Japan because the closure of plants raises the risk of electricity shortages.

Some have also said the government has yet to formulate a clear long-term energy strategy if Japan is to reduce its reliance on nuclear power, which provides more than a third of the country's electricity.

There have already been severe disruptions to power supplies as a result of the March 11 earthquake and tsunami and the subsequent nuclear crisis, and the temporary closure of the Hamaoka facility is expected to lead to further shortfalls.

The plant supplies power to half of Toyota's 18 car factories in Japan. The company, the world's biggest automaker, along with others such as Nissan and Honda, has already suffered heavy disruption to production in Japan since March 11.

The crisis at the Fukushima plant has had global repercussions for the nuclear industry, with many governments responding to public fears by delaying or re-evaluating plans to build more plants.

However, Laurence Williams, a professor of nuclear safety at the University of Central Lancashire in the United Kingdom, said such moves were political decisions, because current International Atomic Energy Agency standards have long identified the need to design for external threats such as earthquakes and tsunamis.

"Operating [a nuclear plant] in a seismic zone is not to be forbidden. People live in these zones, people build large skyscrapers. It's about the standards you build to so these structures can respond appropriately to the seismic threat," he told The National.