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Fukushima Daiichi NPS Prompt Report 2013

Fukushima Daiichi NPS Prompt Report (Oct 20, 2013)No Impact on Seawater: Overflowed from dikes at Fukushima Daiichi NPS

Continuous heavy rainfall, 11 tank areas overflowed; 6 of these above the Discharge Standard

TOKYO - Oct. 20, 2013. Although Tokyo Electric Power Company (TEPCO) was in the course of expanding the capabilities of the Fukushima Daiichi NPS facility to prepare for Typhoon No. 27 (Francisco), due to the continuous heavy rainfall in the Touhoku region, the rainwater in the dikes (*1) has overflowed from 11 tank areas. 6 of these were above the Discharge Standard (*2).
There has been no unexpected exposure to radiation and no impact on the seawater.
TEPCO assumed that the overflow stopped when the rain ended at midnight on Oct. 21.

Once the previous typhoon named Wiphia, typhoon No.26, had passed, TEPCO started transferring the dike water, which had accumulated due to rainwater.
In addition, on Oct. 21, TEPCO was planning to expand the capability of the facility to prepare for Typhoon No. 27 (Francisco) by readying extra water pumps and an extra draining hose.

However, the continuous heavy rainfall exceeded the water transferring capabilities; therefore, water overflowed from the dikes.
Since there are sandbags and sand bank around the outside of each tank areas, the possibility of the direct leakage to the seawater is very limited. TEPCO spokesman Noriyuki Imaizumi, who is the General Manager in Nuclear Power & Plant Siting Division, said that "we will keep monitoring the samplings from the seawater and continue to make every effort to secure the safety of workers."

According to the latest sampling data, the highest level of Strontium-90 was 710 Bq/L at the H2 (South) area; approximately 24 times the government discharge standard for Strontium-90, which is 30 Bq/L. There is no significant change in the monitoring data at the sea area inside and around the power station. Judging by the monitoring results of the seawater, there has no impact on the waters of the ocean. Cesium-134 and Cesium-137 were below the minimum detection levels and have not been found in most of the tank areas.

(*1) Each group of tanks in which the contaminated water accumulates at the Fukushima Daiichi NPS is set up on a concrete foundation and surrounded by a 30 centimeter-tall dike.
(*2) The discharge standard is the provisional standard established by the Japanese government, and is set to be lower than the sea discharge standard value.

TEPCO, Inc. is a provider of electricity to the Kanto region, which includes Tokyo and Yokohama. The company is headquartered in Tokyo. The Fukushima Daiichi Nuclear Power Station was struck by a tsunami after an earthquake that occurred in March 2011. For more information, please go to

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