TEPCO Making Progress on Water Contamination
Jeremy L. Dillon
RW Monitor
11/7/2014
The Tokyo Electric Power Company this week completed the transfer of spent fuel assemblies from the Fukushima Daii-chi Unit 4 spent fuel pool. In what TEPCO deemed “a sold step forward” in decommissioning the plant, the company moved 1,331 fuel assemblies to a centralized storage common pool meant to store the used fuel. The Unit 4 reactor still holds 180 unirridiated fuel assemblies, but according to TEPCO, the radiation dose from new fuel is small enough to handle by hand. To move all the assemblies, the company loaded a cask 62 times by moving the assemblies into the cask in the spent fuel pool, lifting out of the pool using a crane, closing the lid and decontaminating the cask, and then transporting the cask to the common pool. TEPCO started the spent fuel transfer late last year.
While the movement of fuel from Unit 4 is an accomplishment, the milestone was the least complicated of the needed fuel removal. “At the time of the accident, although a hydrogen explosion occurred, all of the fuel rods had been transferred into and stored in the spent fuel pool as part of the periodic inspection,” TEPCO said. “Therefore, they survived relatively undamaged.” In comparison, the fuel rods at Units 1-3 all suffered heavy damage, resulting in fuel debris, and are not so easily transferred. “Since the fuel melted into a state called debris, it became difficult to apply conventional measures to remove it,” TEPCO said. “To deal with this situation, we are planning to conduct the task in parallel with the development of tools and devices for removal, etc. during the decommissioning process, over the next 30 to 40 years.” Units 5 and 6 did not suffer any damage during the accident, and their fuel remains secure in their spent fuel pools.
Water Strategies Making a Difference, Report Says
Also this week, TEPCO announced that its water contamination mitigation strategies are making progress at solving an issue that has plagued the site cleanup since 2011. According to the Nuclear Safety Reform Plan Progress Report, during the second quarter TEPCO made “significant advances in the treatment of contaminated water” at the Fukushima site. The report notes the activation of the ALPS water treatment systems, including a new high-performance ALPS system. “It demonstrates progress in a broad range of important areas,” Dale Klein, former Chair of the U.S. Nuclear Regulatory Commission and Chair of TEPCO’s Nuclear Reform Monitoring Committee, said in a statement. “Among the most significant are advances in implementing a comprehensive approach to manage water at the site of Fukushima Daiichi, the full operation of the new Fukushima D&D Engineering Company under the leadership of Naohiro Masuda, and the inculcation of a safety culture throughout the company.”
The installation of the new high-powered ALPS system last month, along with other water management activities, has TEPCO making strides against water 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.
Kurion Officially Announces Tritium-Removal Demonstration Contract
Meanwhile, Kurion has received a contract worth approximately $10 million from Japan’s Ministry of Economy, Trade and Industry (METI) to demonstrate its tritium-removal technology as a possible remedy at Fukushima, the company officially announced this week. Kurion first previewed its contract with METI back in September when Kurion President John Raymont spoke at the RadWaste Summit in Summerlin, Nev.
METI selected Kurion from among a field of 182 submissions to help fight the growing tritium contamination of water at the Fukushima-Daiichi site. Submissions for the tritium-removal project required the ability to treat 800,000 tons of tritiated water, Kurion said. “We recognize the urgency of the situation as water accumulates at the Fukushima site,” Raymont said in a statement. “While the specified completion date for the project is March 2016, it is our goal to accelerate the demonstration project and provide the necessary data by the end of 2015 to enable the METI, TEPCO and the Japanese people to make an informed decision about the tritium contamination at Fukushima.”
Kurion System Removes Hydrogen
According to the company, tritium has been especially hard to remove from the water tanks due to its chemistry. It is a special form of hydrogen that forms tritiated water, which does not lend itself to removal by conventional technologies, Kurion said, but the company’s Modular Detritiation System uses a process that removes the hydrogen. “The system converts tritiated water (HTO) to gaseous Hydrogen (H2), gaseous Oxygen (O2) and gaseous Tritium (HT); it then separates Tritium (T) for stabilization, enabling the safe disposition of the clean H2 and O2 gas streams (e.g., resold as chemical feedstock, flared to atmosphere, or recombined as H2O),” Kurion said in its release.
According to Raymont, the hydrogen can then be sold. “The Kurion approach for treating tritium at Fukushima offers TEPCO an unlikely option and benefit: it creates a significant Hydrogen feedstock for Japan’s ‘hydrogen economy’ and supports the METI 2015 Hydrogen Initiative to establish hydrogen as an energy source for cars. The 800,000 tons of tritiated water at Fukushima would generate about 90,000 tons of H2,” said Raymont.
Kurion has been heavily involved in the Fukushima cleanup. Earlier this summer, the company announced a contract with TEPCO to provide a mobile system to treat the water tanks at the Fukushima-Daiichi Power Station. Kurion previously provided treatment at the cleanup site to remove cesium from groundwater back in 2011, and the new contract calls for the removal of strontium from the water that is currently being stored in the tanks. According to Kurion, TEPCO liked the system so much it ordered a second mobile processing system to aid in the water treatment. The water in the tanks had previously been treated by Kurion and other similar systems to remove cesium.
