6 years ago
Today for the first time the NRC went on record saying that the Fukushima Unit 4 Spent Fuel Pool was in deep trouble.
Mr Jaczko, who was briefing US politicians in Washington, said the NRC believed “there has been a hydrogen explosion in this unit due to an uncovering of the fuel in the spent fuel pool”.
“We believe that secondary containment has been destroyed and there is no water in the spent fuel pool. And we believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures.”
There has been some disputing going on between Japanese officials and the NRC, but apparently not enough to cloud the trouble, and the apparent plans to address it.
As U.S. and Japanese officials disagreed on how to characterize the seriousness of the nuclear crisis, police planned to use a water cannon truck — normally used for crowd control — to try to cool an overheated and possibly dry spent-fuel pool, one of an escalating series of malfunctions at the Daiichi plant in Fukushima prefecture, 150 miles north of Tokyo. Without cooling, the spent rods could emit radioactive material.
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In Washington, U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko said at a congressional hearing that all the water has evaporated from the spent fuel storage pool at the complex’s No. 4 reactor. Japanese officials have not confirmed that.
While not acknowledging that the Unit 4 SFP is a problem, they acknowledge plans to use a water cannon to get water into the pool.
As I said before boiloff, dryout and zirconium fires in the SFP pose a more significant risk than what is happening inside a hard containment.