FUKUSHIMA – Tokyo Electric Power Co. has finished pumping out radioactive water from all seven of its huge covered trenches at the crippled Fukushima No. 1 nuclear plant, transferring the contents of most to above-ground steel tanks, Tepco officials said.
The last covered trench to be emptied had contained around 3,000 tons of water that was relatively less contaminated than the others because it consisted mainly of seawater that entered the buildings housing reactors 5 and 6 when the plant was engulfed by tsunami moments after the March 11, 2011, Great East Japan Earthquake hit.
Highly radioactive water stored in the six other covered reservoirs had been transferred to more reliable tanks above ground before Tepco started handling the less-contaminated water starting on June 11. It was found that the highly radioactive water that had been pumped into the trenches, which are triple-lined, was seeping into the ground. The covered sunken trenches have raised coamings.
The less-contaminated water was pumped into the basement of the reactor 6 turbine building and will eventually be transferred to above-ground containers, Tepco said late Monday.
The utility first detected the radioactive water seepage from one of the trenches on April 5. Two other reservoirs were also found to have problems, leading Tepco to remove the water from all seven.
Handling the radioactive water remains a challenge for Tepco because the amount increases daily as a result of continuing water injections to cool reactors 1, 2 and 3, which suffered meltdowns after the tsunami hit.
The building housing reactor 4 was also damaged because of a hydrogen explosion.
Workers were able to achieve a cold shutdown of units 5 and 6.