Jeremy L. Dillon
RW Monitor
9/19/2014
While water contamination continues to plague the cleanup of the damaged Fukushima nuclear power plant, the Tokyo Electric Power Company appears to be making headway on the problem. TEPCO announced this week that it has successfully installed and has begun testing an enhanced ALPS water treatment system at the plant. The new ALPS system builds off the existing treatment system in an effort to increase treatment capacity. TEPCO plans to install two additional systems, with one going on-line at the end of the month and the other starting in October. The enhanced systems should be capable of processing 1,500 tons of contaminated water a day in total, twice the capacity of the existing system of 750 tons a day. “The improvements built into the newer ALPS system reflect the lessons learned from the earlier ALPS design,” TEPCO said in a release. “They include new rubber linings to prevent erosion, improved monitoring of water flow, improved leak detection, enhanced backup equipment and enhanced physical barriers to contain any leaks.”
TEPCO’s water treatment strategy appears to be working, according to the company. Late last week, TEPCO announced that seawater monitoring results outside the site show radiation levels well below regulatory limits. The company estimates that strontium has been reduced to approximately a third of earlier levels, while cesium has been reduced to a tenth of the volume. “Cesium [has] now been measured in amounts below [Japan’s Nuclear Regulation Authority] limits in all points,” TEPCO said in a release. “Strontium also has been measured within regulatory limits at most points within the port, except nearest the reactors, where recent measurements show levels of 70-100 BqL compared with the JNRA limit of 30 Bq/L.” After the accident, TEPCO’s immediate concern dealt with cesium removal from contaminated water, while earlier this year, the company awarded a contract to Kurion to expand its role at the site by developing a technology to treat strontium within the contaminated water tanks.
TEPCO also attributed the success in reduced levels with its efforts to prevent further groundwater contamination. Earlier this year, the company announced the launch of its by-pass system that diverts groundwater from the site. The bypass system is an attempt to reduce the accumulation of contaminated water by intercepting the clean groundwater before it reaches the plant by rerouting it around the plant into the sea. TEPCO also began construction of an ‘ice wall,” which freezes the surrounding soil in an effort to block the flow of groundwater. The strategy also includes the construction of a seaside wall aiming to prevent groundwater from flowing into the sea by constructing a steel pipe sheet pile wall on the east side of the site and construction of a subdrain system that will capture underground water and pump the water for treatment. All four systems are part of TEPCO’s three large water management strategies: Contaminant removal, contaminant isolation, and leakage prevention.
