Monju reactor unclogged for restart


A device that fell last August into the vessel of the Monju prototype fast-breeder reactor in Tsuruga, Fukui Prefecture, was finally retrieved Friday, paving the way for resumed test runs by fall, the Japan Atomic Energy Agency said.

But due to the nuclear disaster at the Fukushima No. 1 power plant, triggered by the March earthquake and tsunami, it is unclear whether the country’s nuclear fuel recycling project, in which the troubled Monju prototype would play a key role, can move ahead as planned. Because it is meant to produce plutonium, were it to experience a leak accident, the danger would be grave.

The agency hopes to resume test runs of the reactor at 40 percent of its output capacity by the end of March, aiming for full operation by the end of March 2014.

In a procedure that took about eight hours, a crane was used to remove the 12-meter-long, 3.3-ton device together with part of a vessel lid where it got stuck.

The cylindrical device, used to load fuel, fell inside the reactor vessel while it was being lifted out after completing a fuel exchange.

Attempts made in October to grab the device failed after it had become deformed and was caught against the vessel’s upper lid.

It was a delicate and potentially dangerous operation at the plant on the Sea of Japan coast, because part of the device was soaked in a sodium coolant that can catch fire when it comes in contact with air.

The retrieval work, which started Thursday, was delayed several hours when a rubber part attached to a tube at the lower part of the container was found to be damaged after workers discovered that argon gas was leaking from the tube, the agency said.