The operator of Japan’s tsunami-flooded nuclear power complex is seeking ways to pull damaged spent fuel rods out of a storage pool at one of its reactors, citing surging radiation and elevated temperatures as worrisome signs.
The troubling signals at the Fukushima Dai-ichi nuclear complex come as frustrations grow with Tokyo Electric Power Co’s handling of the crisis since the 11 March tsunami swamped the plant, knocking out crucial cooling systems. Restoring them will take months.
Frequent aftershocks from the magnitude-9.0 earthquake that triggered the monstrous waves are unwelcome reminders of the disaster and are impeding work on the cooling systems.
The government earlier this week revised its rating of the severity of the crisis to level seven, the worst possible on an international scale. The only other level seven was the 1986 Chernobyl disaster, though that explosion released 10 times the radioactivity that has come from Fukushima Dai-ichi so far.
Tepco officials said yesterday they were discussing ways to eventually remove spent fuel rods from storage pools as the plant is closed down for good.
The issue appeared most urgent at the number four reactor, which was shut down for maintenance at the time of the tsunami, with all the spent fuel rods moved from its core. Company officials said they were considering ways to remove the fuel rods for permanent storage, but must first devise ways to reduce radiation leaking from the pool.
Tepco manager Junichi Matsumoto said analysis of the pool’s water detected radioactive iodine-131, caesium-134 and caesium-137. Normally, those elements would not be found in the pool.
High radioactivity in the water may result from damage to the fuel rods but also from contaminated debris and particles spewed from other reactors, Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said.
But he said a failure to inject water into the pool for several days until yesterday, when spraying resumed, may also have caused damage. Water that inadvertently was sprayed into a surge tank, which monitors overflows, appeared to have indicated the pool was full when it actually wasn’t, he said.
“I believe fuel rods in the pool are largely intact, or still keeping the normal shape of what they should look like,” Nishiyama said.
“If they were totally messed up, we would have been looking at different sets of numbers from the water sampling.”
Tepco has also been working to drain radiation-contaminated water from some of the plant’s other five reactors and to stabilise conditions at its No 1 reactor by pumping nitrogen into its containment vessel to reduce risks of an explosion.
The plant’s operator is also installing steel plates and silt screens to help reduce radiation leaks.
The halting progress at the plant has deepened the misery of residents who were forced to leave their homes and jobs near Fukushima Dai-ichi.