Beware of degrading resin

September 03, 2013

TEPCO: Worn resin may be cause of high radiation

http://www3.nhk.or.jp/nhkworld/english/news/20130903_13.html

The operator of the Fukushima Daiichi nuclear plant says degrading resin may be to blame for extremely high radiation detected on the plant's storage tanks.

Tokyo Electric Power Company measured high radiation levels near the bottom of 3 tanks holding radioactive waste water, over the weekend. One of them had beta-ray radiation of up to 1,800 millisieverts per hour.

All the high measurements came from the joints of tanks built of steel plates that are bolted together. Workers found resin extruding from the joints. The resin is used inside the seams as a "water-stop" material because it expands when soaked with water.

TEPCO officials believe wear and tear caused the resin to extrude from the steel joints. They say there's no trace of water leakage from the joints, and no high levels of radiation have been measured on the ground beneath.

But they say they will look into the problem further, as degrading resin could result in leaks.

The company has been stepping up monitoring of tanks since a leakage of more than 300 tons of radioactive water was found from a single tank in mid-August.

But increased patrols have only led to more discoveries of hot spots. On Monday, beta-ray radiation of more than 100 millisieverts per hour was detected on another tank in a different area.