On July 23, there have been some reports about installing used flange type tanks (bolted tanks) partially installed to store contaminated water at Fukushima Daiichi NPS from a few media which questioned about the quality of the tanks. This may provoke some anxiety about the safety and reliability of the tanks being used to store water at the Fukushima Daiichi Nuclear Power Station.
However, the storage tanks are secured and here are the facts about the storage tanks at Fukushima, and about the water management efforts of which they are a part.
•The tanks are safe: When installing the tanks at Fukushima Daiichi NPS, TEPCO expects for 5 years of its sustainability and there is no requirement differece between the new and used tanks. In fact, all tanks are examined by water-filling testing before actual usage. And the material which is used for the joint of the flange type tanks is brand new packing, even if it was used, TEPCO considers there will be no effect for the sustainability of its use. Furthermore, TEPCO has enhanced water management by conducting tank patrol 4 times a day and monitoring water level indicator around the clock.
•Replacement of the flange tanks: the need to protect the environment was paramount, the need to store contaminated water immediately after the March 2011 accident at Fukushima was great. As a result, installing storage tanks at Fukushima Daiichi, which meets the standard of integrity, was essential regardless of different types of tanks. TEPCO will replace the flange type tanks to welded type tanks from September, 2014 which are less likely to occur leakage.
•Comprehensive water management: As we have said previously, the tanks are an important part of a comprehensive water management plan in which the need for additional storage tanks is expected to diminish over the next few years. Just in the last several months, we have made major progress toward (1) reducing the amount of water that becomes contaminated, and (2) cleaning the water that does become contaminated. For example:
1.We successfully initiated a groundwater bypass system that keeps some groundwater from entering the facility. Continuous testing has demonstrated that this water remains clean enough to discharge into the ocean - where the groundwater would naturally go. The government and local fishermen have agreed to this discharge, with water being held to a standard far stricter than those usually applied to ocean discharges, and with continuous independent monitoring. To learn more (video) http://www.tepco.co.jp/en/news/library/archive-e.html?video_uuid=z2w288fm&catid=61795
2.We will be upgrading and expanding the water treatment systems (ALPS) so that they will be more durable and remove all nuclides (except tritium), enabling the safer storage of water and potentially reducing the need for storage capacity.
3.We erected an impermeable wall on the sea-facing side of the plant that is designed to prevent contaminated groundwater from reaching the ocean. This, together with restored sub-drain and pumping systems that were damaged in the March 2011 accident, is expected to further reduce the already dramatically reduced levels of contamination in the port area adjacent to the plant.
4.With the assistance of the government and Kajima Corp., we began construction of the “ice wall,” a system designed to freeze the soil around the entire perimeter of Units 1-4, blocking groundwater from entering the reactor building basements and dramatically reducing the accumulation of contaminated water from its current level of 400 tons per day. This, in turn, will reduce the need for more storage tanks and will also free up capacity in the water treatment systems to clean water that is already being stored. To learn more (video) http://www.tepco.co.jp/en/news/library/archive-e.html?video_uuid=kyt26951&catid=61795
We are committed to pursuing these and other strategies to manage water on the site, something that will remain a challenge while the work to decontaminate and decommission Fukushima Daiichi continues over the years. And we are committed to transparency about these activities.
To read more about TEPCO’s countermeasures for contaminated water please visit http://www.tepco.co.jp/en/decommision/team/images/FukushimaDaiichiDandD_02.pdf