Leakage of Contaminated Water from the Top Plate of a Tank at B Area (South)


Print View Posted on: 16 April 2015

Event Date: 02 October 2013 Event Type: Power Reactor
Event Location: Japan, FUKUSHIMA-DAIICHI INES Rating: Not Applicable (Final)

On 2 October, 2013, TEPCO found a water dropping from around the top plate of B area (south) tank (No.5 tank at Group A in B area), in where treated water from the desalination apparatus is stored, at Fukushima Daiichi NPS.
The leaked water was not only dropping inside the dike, but also dropping to outside of the dike at B area (south) via the scaffold installed around the tank for inspection.
Because it cannot be denied that the water leaked from the top plate of the tank flowed into the drainage channel via the side ditch nearby, and leaked into the sea, TEPCO performed water-stop measures by putting sandbags in the side ditch which connects to the drainage channel.
The radioactivities of the water leaked into the sea were approximately as follows.
- Total Beta: 6.5 MBq
- Cesium-134: 52kBq
- Cesium-137: 130kBq
There has been no contamination of the ocean that raises any concern about influence to heaith and the environment.

INES Rating: Not applicable (Final) as per 16 April 2015
Release beyond authorized limits? No
Overexposure of a member of the public? No
Overexposure of a worker? No

Contamination spread within the facility? Yes
Damage to radiological barriers (incl. fuel damage) within the facility? No

Degradation of Defence In-Depth Yes

Person injured physically or casualty? No
Is there a continuing problem? No

Shoji Takeyama
Nuclear Regulation Authority

shoji_takeyama@nsr.go.jp
http://www.nsr.go.jp/english/index.html
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