TOKYO (Kyodo) -- The operator of the disaster-stricken Fukushima Daiichi nuclear complex was set to attempt to remove a small amount of melted fuel from one of its crippled reactors on Thursday, but decided to put the trial extraction on hold due to issues discovered during preparations.
Tokyo Electric Power Co. has not said when it will try again after suspending the operation on Thursday morning after setup errors were identified in the debris retrieval device.
It is the first such attempt to remove debris by TEPCO since the plant in Fukushima Prefecture was devastated by a massive earthquake and tsunami over a decade ago.
"It is better to carry on with the work safely and steadily rather than rushing," TEPCO President Tomoaki Kobayakawa told reporters in Niigata prefecture, where he was visiting to discuss another reactor operated by the company.
The trial will only seek to retrieve a few grams of fuel debris from the No. 2 unit over approximately two weeks. Methods of removing all the melted fuel remaining in the No. 1 to No. 3 reactors have yet to be decided, leaving major challenges in the plant's decadeslong decommissioning plan.
TEPCO has chosen the No. 2 reactor as the first to start the fuel debris retrieval work, as the situation inside is understood more clearly than the others.
Among the three reactors that experienced core meltdowns in the accident, the reactor building housing the No. 2 unit was the only one not to suffer a hydrogen explosion.
The No. 2 unit was in operation when the emergency began and some fuel is believed to have melted through the reactor pressure vessel that holds the fuel and accumulated at the bottom of the outer primary containment vessel. It is thought to have mixed with materials such as cement from the surrounding area.
According to the plan, TEPCO hopes to retrieve up to 3 grams of debris using a telescopic device equipped with a gripper tool. The device can extend up to 22 meters and access the debris through a penetration point in the primary containment vessel.
Steps have been taken to limit radiation emissions from the stricken reactor, with a valve system installed as a barrier.
