Last week, TEPCO announced that radioactive water was leaking from temporary underground storage pits, and was likely to continue until the water could be transferred. The first reported leak occurred in a tank located some 800 meters from the Pacific Ocean which contained processed water which had been used to cool down the crippled reactors at the Fukushima Daiichi complex. The utility later reported that water found around the tank had also been found to be contaminated, but did not say how long the tank had been leaking.
The temporary storage pits are some 60 meters long, 53 meters wide, and 6 meters deep and lined with three layers of water proof sheets meant to keep the contaminated water from leaking into the surrounding environment. According to the utility and the Nuclear Regulation Authority, radiation levels between the waterproofing sheets used to layer the pits were measured around 6,000 becquerels per cubic centimeter. TEPCO reported that some 120 tons of contaminated water had leaked from the tank between Wednesday and Friday and estimated over 700 billion becquerels of radioactive strontium had already leaked at the time of announcement.
On Saturday, workers began using pumps to transfer the remaining 13,000 tons of highly contaminated water to an adjacent tank and storage pit. The next day, Sunday, TEPCO admitted that a second temporary underground storage pit was leaking as well. The second leaking pit contains 10,000 tons of contaminated water.
TEPCO will likely have to review its temporary storage strategy, but so far has only released plans to continue monitor the levels of radioactive materials in the soil around the tank and look for a new storage location. The Japanese utility believes that the radioactive water may have leaked out through joints in the tank’s seepage control sheets.
Masayuki Ono, a senior Tepco official, said at a news conference Sunday that it is difficult for the plant to store all of the radioactive water in the temporary tanks, which is why they were forced to keep the contaminated water in underground pits.
Source: The Japan Times