Fukushima Daiichi NPS Prompt Report 2015

Source may be rainwater puddles formed on the rooftop of Unit 2 reactor building; the investigation is not related to Sunday's temporal rise in a separate drainage

FUKUSHIMA, February 24, 2015―Tokyo Electric Power Company announced today that a source of relatively high radiation in one of the drainage channels at Fukushima Daiichi NPS may be a puddle of rainwater which accumulated on the rooftop of the Unit 2 Reactor Building, which contains one of the reactors that suffered a meltdown during the 3.11 accident.

Radioactive material concentration in the water inside one of the several drains, named "Drainage K", has been consistently higher (around ten to several hundred becquerels per liter of Cesium137) than the other drains since monitoring started in April 2014.

The company detected a temporary rise in radioactivity in another drainage channel named "Drainage C" on Sunday, an incident which the company is currently investigating the potential causes for.  The report submitted to the Nuclear Regulatory Authority today explains the result of the investigation into the upstream branch pipes of "Drainage K" which leads to the rooftop of the Unit 2 reactor building.

The company explained that radiation levels are high in puddles where radioactive materials accumulate and are contained.  Radioactive materials are also likely to accumulate within the structure of the rooftop, the company said. As the company inspected the rooftop, 23,000 becquerels per liter of Cesium137 was detected from the puddle.  Cesium137 levels in rainwater collected from other spots on the rooftop ranged from 650 to 1,100 becquerels per liter.

After recognizing the high levels in "Drainage K", TEPCO has been installing "zeolite" materials, which remove Cesium from water, inside the channel for the water to pass through. The company said it is also planning to install the "zeolite" around the rainwater drain on the rooftop of Unit 2.

For detail, please go to http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150224_01-e.pdf

About TEPCO

Tokyo Electric Power Company, Inc. (TEPCO) is Japan's largest power company, supplying energy to the greater Kanto area, including Japan's two most populous cities, Tokyo and Yokohama. Its 34,000 employees are committed to providing safe, reliable power to its 29.0 million customers, diversifying energy resources to ensure sustainability, and contributing to economic growth while fully meeting its responsibilities after the Fukushima Daiichi accident.
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