Decommissioning work in parts of the Fukushima Daiichi plant in Japan has been delayed after engineers discovered that sandbags placed in the basements of buildings near Units 1 and 3 were found to contain excessive radiation levels. Tokyo Electric Power Company (TEPCO) operates the plant and is in charge of the decommissioning efforts following the accident caused by the earthquake and tsunami on March 11, 2011.
The details:According to an April 19 email to Nuclear News from TEPCO representative Joji Hara, sandbags at the Process Main Building (PMB) had a maximum radiation level of 3,000 mSv, while sandbags at the High Temperature Incinerator Building (HTI) had a maximum level of 4,000 mSv. TEPCO originally had placed 26 tons of sandbags in the basements of the two buildings near the Unit 1 and Unit 3 reactors, and surveys of the sandbags were done in late 2019. The sandbags are packed with a mineral called zeolite to absorb radioactive cesium, and TEPCO planned to have the contaminated water in the buildings removed in 2020. Now, TEPCO estimates not being able to remove the water until 2023 or later.
The next step: TEPCO is considering two methods to deal with the highly radioactive sandbags. The first is to remove the zeolite and the other materials by using equipment similar to a vacuum cleaner. The second involves using a vehicle similar to a bulldozer to collect the zeolite and other materials. In either case, all work would be done underwater, and the removed materials would be stored inside appropriate containers.
Final word: “The water level of the accumulated contaminated water inside the buildings is now being lowered in order to complete the task of floor exposure,” according to Hara. “For the PMB and HTI, countermeasures to lower the radiation level of the sandbags will be taken before completion of the [water removal] task.”