5 Sept (NucNet): Radiation levels near tanks containing contaminated water at the Fukushima-Daiichi nuclear power plant have fallen after measures to prevent leaks were implemented by plant operator Tokyo Electric Power Company (Tepco).
Tepco said in a statement today that on 3 September 2013 it had used “sealing materials, acrylic boards and rubber mats” as a trial shielding method for reducing radiation near water storage tanks.
Tepco said the local radiation dose rate on the north side of one tank, tank number 4 in the H3 area, was 2,200 millisieverts an hour (mSv/h) on September 3, but fell to 30 mSv/h following the implemented shielding steps. On the south side of the tank, the local radiation dose rate was 500 mSv/h on 3 September, but measurements taken today show it has fallen to 15 mSv/h.
At tank number 10 in the H3 area, the local radiation dose rate was 70 mSv/h on 3 September, but has now fallen to 10 mSv/h, Tepco said.
The measurements were taken near the base of the tanks, about five centimetres above ground level.
Recent leaks of contaminated water were reported on 19 August 2013 when water was discovered inside and outside a dike surrounding a wastewater tank.
On 21 August, the Japan Nuclear Regulatory Authority revised its rating of this leak from a Level 1 to a Level 3 on the International Nuclear and Radiological Event Scale.
The storage tanks were built following the March 2011 accident at the plant to hold radioactive water.
Tepco said last week that an estimated 300 cubic metres of water had escaped from one of the tanks, leaving “hot spots” of pools of radioactive water.
In a statement earlier this week, Tepco expressed its regret for the latest problem to strike the plant.
“We deeply apologise for the great anxiety and inconvenience caused by the recent contaminated water issues at Fukushima-Daiichi, which affect residents near the power station and the broader society,” the statement said.
“We will investigate the cause of this issue, taking any appropriate countermeasures immediately, and continue to make every effort to secure the safety of workers.”