Security & Safety
13 Aug (NucNet): Almost 90 percent of spent fuel assemblies from the spent fuel pool at Fukushima-Daiichi Unit 4 have been transferred to a central storage pool with the remainder scheduled to be removed by the end of the year, operator Tokyo Electric Power Company (Tepco) said.
Tepco said in a report published online that of the 1,331 spent fuel assemblies in the pool, 1,166 units had been removed, with 165 remaining.
According to Tepco, there were initially 1,533 fuel assemblies in the pool, with 1,331 used and 202 unused.
Unit 4 at Fukushima-Daiichi was already shut down for a regular inspection when the station was hit by an earthquake and tsunami in March 2011 and all spent fuel assemblies had been transferred to the spent fuel pool. The unused assemblies were being prepared to be inserted into the reactor when the disaster happened.
Tepco also said in the report that while there had been a decline in leaks from storage tanks that were built following the accident to hold radioactive water, the leaks “have not been entirely eradicated”.
The report says Tepco has applied for government permission to restart the Kashiwazaki Kariwa nuclear station and continues to make improvements to the facility in anticipation of it eventually being returned to service.
Japan’s nuclear regulator has begun examinations into whether units 6 and 7 of the Kashiwazaki Kariwa station comply with new regulatory standards and are ready to be restarted.
Kashiwazaki Kariwa-6 and -7 are both 1,315 megawatt advanced boiling water reactors brought into commercial operation in 1996 and 1997 respectively.
The seven-unit Kashiwazaki Kariwa plant was not directly affected by the March 2011 earthquake and tsunami, but it was struck by an earthquake in July 2007 leading to the automatic, safe shutdown of units 3, 4 and 7. Units 1, 5 and 6 were already shut down at the time of the earthquake for periodic inspections.
Unit 2 was technically undergoing a periodic inspection and start-up operations had just begun, but the unit was also shut down safely.
Tepco restarted units 1, 5, 6 and 7 at the plant after repair of damaged systems and inspections. But these units have since been shut down for planned refuelling and maintenance and not yet restarted following government-mandated safety checks in the wake of the Fukushima-Daiichi accident.
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