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How to extract fuel debris

How to extract fuel debris

July 5, 2017


Fuel debris extraction plan for crippled Fukushima reactors to be revealed soon: sources





A state-backed entity is close to completing a plan for decommissioning the crisis-hit Fukushima nuclear power plant, detailing for the first time how it hopes to extract fuel debris from three reactors, sources said.


The Nuclear Damage Compensation and Decommissioning Facilitation Corp., tasked with providing technical support for decommissioning the complex, may propose a method to remove nuclear debris without completely filling the reactor containment vessels with water, the sources said Tuesday.


The plan means the debris inside reactors 1, 2 and 3 at the crippled Fukushima No. 1 complex is likely to be shaved off gradually with a drill or laser equipment as a shower of water is poured remotely, the sources said.


Filling reactor containment vessels with water before removing the debris is seen as effective in blocking the spread of radiation, but the entity decided not to adopt the approach because they fear water may leak from the damaged structures, the sources said.


In the method currently being weighed, some debris would remain in the air during the operation, posing a major challenge in efforts to block radiation and prevent debris from flying off, the sources said.


While debris has yet to be directly confirmed and information on exact locations and conditions is limited, the extraction work — the most difficult part of the decommissioning project — is expected to proceed in stages from the side of the bottom part of each reactor containment vessel, the sources said.


Based on the plan, the government and the plant operator, Tokyo Electric Power Company Holdings Inc., are expected to determine a course of action for each reactor building this summer, possibly reviewing a road map for decommissioning the entire complex as well, the sources added.


Decommissioning the crippled reactors is expected to take at least 30 to 40 years.

The current road map calls for a debris-extraction plan for each reactor by this summer, with a detailed plan for at least one of the units ready in the first half of fiscal 2018. Extraction work would begin in 2021.


Following a magnitude 9.0 earthquake in March 2011, tsunami waves inundated the six-reactor plant, located on ground 10 meters above sea level, flooding power supply facilities. Reactor cooling systems were crippled and reactors 1, 2 and 3 suffered fuel meltdowns, while hydrogen explosions damaged the buildings housing reactors 1, 3 and 4.


At least 150,000 people in Fukushima were forced to live as evacuees amid radiation fears. While some have returned to their homes, Tepco and the government face enormous challenges in scrapping the reactors.


The Nuclear Damage Compensation and Decommissioning Facilitation entity was established after the crisis, the worst nuclear disaster since Chernobyl, to help the utility pay damages. The state-backed entity holds a majority stake in Tepco.


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