Accident in Fukui Pref. would impact millions in neighbouring pref.

 November 18, 2013

Nuclear accident could contaminate Lake Biwa

http://www3.nhk.or.jp/nhkworld/english/news/20131118_37.html

Shiga Prefecture in western Japan warns that a nuclear accident at a power plant in the neighboring prefecture could taint drinking water drawn from Lake Biwa.

Shiga prefectural officials on Monday compiled a report on the impact of a major nuclear disaster at one of Kansai Electric Power Company's nuclear plants, in Mihama or Ohi, in neighboring Fukui Prefecture. The disaster is simulated as being on the scale of the 2011 Fukushima accident.

The prefecture based its assumptions on weather factors such as rain and wind. It says a nuclear accident would release radioactive iodine and cesium, and contaminate Japan's largest lake.

Iodine levels would exceed the nationally acceptable 300 becquerels per liter at depths of up to 5 meters. Tap water is taken at that depth.

The estimated contaminated area accounts for 21.7 percent of the lake's total surface area of some 670 square kilometers.

The levels of Cesium 137 would also exceed the state limit of 200 becquerels per liter at up to 18 percent of the lake's total area.

The state levels are temporary and only applied in times of emergency. The simulated contamination would remain above permissible levels for about 10 days in some parts of the lake.

Shiga prefecture plans to assess the mid- to long-term impact of nuclear accidents, and to find ways to remove the nuclear materials at water purification plants.

The findings will be reflected in the prefecture's disaster preparedness plan.

Shiga Governor Yukiko Kada stressed the need to share information with some 14.5 million residents in western Japan who use water from Lake Biwa.

Professor Haruo Hayashi of Kyoto University's Disaster Prevention Research Institute says the findings effectively pinpoint the need for an evacuation plan for wider areas than initially projected. Hayashi heads Shiga Prefecture's disaster preparedness efforts.

Kansai Electric Power Company has 11 reactors at three nuclear power stations in Fukui Prefecture. All of them are currently idle. The plants are located about 30 to 60 kilometers from Lake Biwa.