Workers at Fukushima Daiichi tackled a leak in a water treatment system caused by a maintenance error. No ill effects have been reported from radiation exposure during the repair.
|Workers in action reconnecting the pipe
Tokyo Electric Power Company (Tepco) said a joint between two pipes was mistakenly loosened at around 9.35am this morning. In response a team of eleven workers cooperated to stop the water flow by closing a nearby valve and then reconnect the pipe. This was completed by 10.50am.
A significant amount of partially treated water leaked within the facility building, accumulating in a dyke installed there to contain any such leaks. The entire area behind the dyke of about 720 square metres was covered by the water to a depth of a few centimetres. After working in these conditions six of the eleven workers were found to have been in contact with radioactive material in the water, said Tepco, which has not reported any ill effects. No contamination was found on the workers faces, leading to the conclusion that no material had been ingested.
Tepco measured radiation dose rates at the water surface as 1.2 mSv per hour for beta radiation, which reaches only around 15 centimetres in air, and 80 times less for long range gamma radiation. This means workers could avoid most radiation risk with their protective clothing and by maintaining distance from the water, although a certain proximity was inevitable in carrying out the repair.
The incident occurred in the desalination system, which comes after the SARRY process to remove caesium and before some water is recirculated to cool the reactor buildings. Tepco said that enough water is stored for cooling that the incident had no effect on that function. After desalination another stream of water goes through an additional ALPS facility which removes other contaminants and is then stored pending eventual regulatory permission to discharge.
Researched and written
by World Nuclear News