Discovery of a Crack in a Connection Valve between Tanks for Concentrated Water Treated by Reverse Osmosis


Print View Posted on: 16 April 2015

Event Date: 17 September 2014 Event Type: Power Reactor
Event Location: Japan, FUKUSHIMA-DAIICHI INES Rating: Not Applicable (Final)

On 4 September, 2014, TEPCO found that the concentrated water* treated by Reverse Osmosis (RO) was leaking from a connection valve between A5 tank and A6 tank in the G4 South Tank Area.
The leaked water was remaining within the dike surrounding the area.
The radioactivities of the leaked water were approximately as follows:
-Total Gamma: 27kBq
-Total Beta: 98 MBq
As a result of inspection by TEPCO, it was found on 17 September, 2014, that the connection valve had a crack which penetrated the valve.

*Concentrated water treated by RO: Concentrated saline water remaining after the desalination by RO. Contaminated water in the basement of reactor and turbine buildings undergo cesium removal, and are then treated by RO for desalination.

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? Yes

Degradation of Defence In-Depth No

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

Shoji Takeyama
Nuclear Regulation Authority

shoji_takeyama@nsr.go.jp
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