Fukushima fuel extraction plan in the pipeline?

Local news has been  reporting of a state-backed corporation coming up with a way to decommission Fukushima No. 1 Nuclear Power Plant through an unconventional method that could cause even more radioactive emissions from the the crisis-stricken plant.

The Nuclear Damage Compensation and Decommissioning Facilitation Corp., which was established after the March 2011 crisis to help utility TEPCO with its massive indemnifications, has also been involved with providing technical support for decommissioning the complex. Now, however, it is believed to be on the verge of announcing a method to remove nuclear debris within the three stricken reactors that does away with filling the reactor containment vessels with water.

The method reportedly under consideration is to use drills or lasers to gradually shave off the debris, with water sprayed in remotely.

Normally filling containment vessels with water is considered essential before removing radioactive debris in order to prevent the spread of radiation. An expert who was asked about this new method said that new approaches were important as the conventional approach might prove difficult due to the possibility water may leak from the damaged structures.

The argument about whether or not water “might” leak form the vessels or not is moot -- the ground water issue that has stymied decommissioning progress at the plant is already well known to have been caused by leaks from the reactors. Even officials from Japan’s International Research Institute for Nuclear Decommissioning (IRID) have stated that the vessels are riddled with holes. 

“The safest way to remove the fuel is to fill the primary containment vessel with water and … under such a condition maybe the workers can access the fuel debris underwater,” Kazuhiro Suzuki, executive director of IRID, told me while researching “Yoshida’s Dilemma.”  However, hundreds of holes and cracks and other damaged components would need to be fixed first, perhaps with the help of robots and a kind of nuclear fuel-proof sealer, he added. “With the high radiation levels, just to fix all of these is very difficult,” he said.

The new method apparently under consideration would mean that some debris would remain in the air during the operation, meaning radioactive materials could fly off into the air.

However, even if the new method should prove to be viable there is still one major hurdle to be cleared first: Finding out exactly where the debris is located. 

Previous forays into the reactors using a number of robotic devices developed by IRID and nuclear component developers such as Hitachi have been largely unproductive in clarifying the situation. It is hoped that latest investigation, which is reported to  be taking place this month, will make some headway inside reactor 3, though experts are unsure if it will be enough to encourage any concrete plan of debris removal there. The previous investigation, inside reactor 2, was equally inconclusive, though it did prompt TEPCO to announce that radiation inside the reactor is of such a high level as to be life-threatening.

Sources: NHK, Asahi Shinbun, Kyodo