Adding 4 meters to Hamaoka plant

September 28, 2013

Utility heightening tsunami breakwater at most vulnerable nuclear plant

http://ajw.asahi.com/article/behind_news/social_affairs/AJ201309280046

THE ASAHI SHIMBUN

OMAEZAKI, Shizuoka Prefecture--Chubu Electric Power Co. has started work to heighten the breakwater at its Hamaoka nuclear plant by 4 meters to clear a hurdle in its application to restart its reactors.

The 1.6-kilometer-long structure currently stands at 18 meters and is designed to protect the nuclear plant--and its five reactors--from tsunami damage. The Hamaoka plant is widely seen as the nuclear plant at most risk in the event of a powerful earthquake.

The decision to heighten the breakwater came after a Cabinet Office panel released a new estimate in August 2012 that said the maximum height of tsunami could be 19 meters if a major quake strikes the region.

The additional work, which started on Sept. 27, involves welding steel tubes to the top of the breakwater along a 170-meter section on the western edge of the structure. The tubes will later be covered with reinforced concrete.

For the rest of the breakwater, 4-meter-tall steel plates will be installed at the top of the wall.

Chubu Electric intends to strengthen the foundation of the breakwater near the No. 4 and 5 reactors as an additional safeguard.

The utility puts the construction costs of the entire breakwater at 150 billion yen ($1.52 billion). Completion is expected by September 2015.

Chubu Electric shut down the plant after Prime Minister Naoto Kan made the request in May 2011, two months after the Fukushima nuclear disaster unfolded. Kan cited the high probability of a devastating earthquake hitting the region.

Such a quake along the Nankai Trough, a subterranean trench stretching from Suruga Bay off Shizuoka Prefecture along the Pacific coastline, could strike the region within decades, according to the Cabinet Office’s report.