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Important Report from TEPCO

The Tokyo Electric Power Company, Incorporated, would like to make comments on subjects that are reported by the newspapers, TV or websites.

Groundwater Bypass Plan
- For Suppressing Increase of Contaminated Water -

May 29, 2013

Regarding the contaminated water problem, we deeply apologize for the anxiety it brought to the society. Here, we provide explanation on our groundwater bypass plan.

- Groundwater flows from the mountain side to the sea side within the power station site, and the water quality of the groundwater has been verified* as having a sufficiently low radioactivity density.

- The groundwater bypass plan has been designed to reduce the amount of water flowing into the reactor buildings (the amount of contaminated water) by altering the flow of groundwater and lowering the water level of groundwater, which is to be achieved through pumping up groundwater at the mountain side before it flows into the reactor buildings where contaminated water has been accumulated

* As a result of water quality inspection on water from pump wells

1. Part of groundwater that flows from the mountain side to the sea side within the power station site is currently flowing into the reactor buildings, and this inflow is responsible for the continuous increase of contaminated water.

2. To cope with this, we are working on the advancement of the “groundwater bypass (Reference 1)” plan designed to reduce the amount of water flowing into the reactor buildings by altering the flow of groundwater and lowering the water level of groundwater, which is to be achieved through pumping up groundwater at the mountain side before it flows into the reactor buildings.

3. In the groundwater bypass plan, water pumped up at the mountain side will be temporarily stored in a tank. Then, each time before releasing the water, we will verify that the radioactivity density of the water is below the allowance limit (Cesium137:1Bq/L), that is, at the same level as that of the nearby rivers.

4. We have installed: wells (pump wells) that pump up groundwater; tanks exclusively for water quality verification; and piping exclusively for transferring groundwater. We have performed water quality inspection on groundwater collected at the pump wells and accumulated in a temporary storage tank, and have confirmed that the radioactivity density of the water is sufficiently low (Reference 2).

 

(Reference 1) Groundwater bypass

(Reference 2) Water quality inspection before start of operation (as of June 12)

  • *1Results are obtained through detailed analysis with increased measurement accuracy. The results shown for the pump wells are the largest values found among the pump wells Nos. 1 to 12.
  • *2"ND" indicates a case where the analysis result is below the detection limit value of radioactivity density.
  • *3The total radioactivity density of Cesium 134 and Cesium 137.
  • *4Analysis underway. (Data on strontium-90 will be obtained after the start of operation.)
 Pumped-up water will be temporarily stored in a tank. Then, each time before releasing the water, we will verify that the radioactivity density of the water is sufficiently low.

 

(Reference 3) Effect on human body (radiation exposure)

 We consider that direct oral intake of groundwater from the pump well would affect a human body to a negligible extent.