ANS webinar updates progress at Fukushima

March 3, 2021, 9:25AMNuclear News

The accident at Japan's Fukushima Daiichi nuclear power plant on March 11, 2011, has sparked many safety improvements in the nuclear industry over the past decade. Lessons from the accident and its aftermath will influence firms and regulators as they consider the future design, construction, operation and decommissioning of nuclear reactors.

An American Nuclear Society webinar, “Nuclear News Presents: A Look Back at the Fukushima Daiichi Accident,” held yesterday was attended by more than 1,550 viewers and generated about 150 questions to the panelists. The attendance was the largest ever for an ANS webinar.

The panelists were Mike Corradini, emeritus professor, University of Wisconsin; Dale Klein, former chairman of the U.S. Nuclear Regulatory Commission; Joy Rempe, principal, Rempe and Assoc. LLC; Lake Barrett, senior advisor, Tokyo Electric Power Company and Japan’s International Research Institute for Nuclear Decommissioning (IRID); and Paul Dickman, senior policy fellow, Argonne National Laboratory.

The webinar’s recording and slides are available here, along with an e-version of the March issue of Nuclear News, which features a cover story on the Fukushima Daiichi accident.

Fukushima update: Lake Barrett, senior advisor to TEPCO and IRID, said that the psychological damage caused by Japan’s March 2011 earthquake and ensuing accident at Fukushima Daiichi overshadows the physical damage of the events.

“No one died from radiation at Fukushima, but unfortunately some did die from the psychological stress from the accident,” Barrett said during the webinar. “The real impacts were not nuclear health physics or biological at all but were substantial and remain important factors now and in the future.”

Barrett said that while much remains to be done in remediating the plant site, which pose immense technical challenges, he is confident that the Fukushima decommissioning team can get the job done. “The technical challenges, as large as they are, are not as difficult as social/political challenges they face,” he added.

Later, during the Q&A portion of the webinar, Barrett said that professional societies such as ANS and other technical and scientific organizations have a role to play in addressing some of those social and political issues.

Comparison to TMI-2: Barrett said that the general approach in the decommissioning of the Fukushima site is much like the approach taken in response to the Three Mile Island Unit 2 accident of 1979. As an NRC site director at the time, Barrett was responsible for overseeing the stabilization and cleanup of TMI-2.

“The details are of course different, but the principles are the same, with risk-reduction being the primary consideration,” Barrett said of the two sites. Working from the outside in, he explained, decommissioning crews will safely maintain the stability of Fukushima’s reactors, eventually gaining access to remove and package the core debris, all while controlling and minimizing the release of radioactive materials.

Fukushima water: One of the biggest challenges in the remediation of Fukushima is the management of processed water at the site. The processed water, which has been cleaned of radionuclides except for tritium, is currently stored in more than 1,000 tanks containing over a million tons of water. TEPCO is currently awaiting a decision by the Japanese government on what to do with the water.

Barrett said that he, along with other authorities, have recommended that the water be diluted and discharged to the sea in a controlled, monitored release, as is done safely at nearly every other nuclear power facility in the world.

“This complex social/political issue is virtually identical to what we faced at Three Mile Island,” Barrett noted. “But there we had only 9,000 tons of water after recycling.” Over a period of 13 years, the TMI water was evaporated, Barrett said, adding that evaporation at Fukushima would not be as simple because of the amount of salt in the water.

In his following presentation, Paul Dickman also noted that nuclear power plants commonly release tritium in a safe manner (each year, he said, the U.S. nuclear power fleet releases nearly double the amount of tritium that is stored at Fukushima), and that release to the sea is the most practical solution for Fukushima’s stored water.

The problem, Dickman said, is that TEPCO is being prevented from releasing Fukushima’s water because of political reasons. “What has happened is the water at Fukushima has become a surrogate for many grievances,” he said, adding that other Asian countries are using the water as an excuse for imposing trade embargoes.

Unit 3 SFP defueling: Barrett reported that just days earlier, on February 28, the last of the 566 fuel assemblies were safely removed from Fukushima’s Unit 3 spent fuel pool. To remove the fuel from the pool, Barrett said that TEPCO used a sophisticated robotic system that is remotely controlled from 500 meters away. The same system was used to remove debris that was covering the fuel rack, as well as the fuel in the racks, he said, adding that some of the fuel assemblies were damaged by falling debris and jammed in the fuel rack.

The cost: During the Q&A portion of the webinar, Barrett said that it will likely cost between $60 to $100 billion to remediate the Fukushima site.

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