Contaminated water leakage from a water tank

Print Posted on: 06 February 2015

Event Date: 19 August 2013 Event Type: Power Reactor
Event Location: Japan, FUKUSHIMA DAIICHI INES Rating: Not Applicable (Final)

・Regarding the contaminated water leakage from a water tank in the H4 Tank Area at Fukushima Daiichi nuclear power station that was detected on August 19, 2013, radioactivity concentrations in the water in the leaking tank were :
- Cesium-134: 44 Bq/cm3
- Cesium-137: 92 Bq/cm3
- Strontium-90: 150 kBq/cm3
- β emitting radionuclides in total: 410 kBq/cm3
・The amount of the leaked water is estimated to be approximately 300m3, judging from the decrease of water level in the water tank in question.
・No significant increase in radioactivity was detected in the seawater near the ditch, while high air dose rates were observed in the ditch that flows into the sea.

INES Rating: Not applicable (Final) as per 10 December 2014
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 Yes

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

Shoji Takeyama
Nuclear Regulation Authority