US nuclear experts warn that pumping seawater to cool an earthquake-hit Japanese nuclear reactor is an “act of desperation” that may foreshadow a Chernobyl-like disaster.
Several experts, in a conference call with reporters, have also predicted that regardless of the outcome at the Fukushima Daiichi plant, the accident will seriously damage the nuclear power renaissance.
“The situation has become desperate enough that they apparently don’t have the capability to deliver fresh water or plain water to cool the reactor and stabilise it, who now, in an act of desperation, are having to resort to diverting and using seawater,” said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies.
“I would describe this measure as a Hail Mary pass,” he added, using American football slang for a final effort to win the game as time expires.
An 8.9-magnitude earthquake that struck Japan on Friday set off the emergency at the plant, which was then hit by an explosion that prompted an evacuation of the surrounding area.
Workers doused the stricken reactor with seawater to try to avert catastrophe after the quake knocked out power to the cooling system.
What occurred at the plant was a “station blackout,” which is the loss of offsite air-conditioning power combined with the failure of onsite power, in this case diesel generators.
“It is considered to be extremely unlikely, but the station blackout has been one of the great concerns for decades,” said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.
“We’re in uncharted territory,” he said.
‘Time will tell’
The reactor has been shut down but the concern is the heat in the core, which can melt if it is not cooled. If the core melts through the reactor vessel, Dr Bergeron explains, it could flow onto the floor of the containment building.
If that happens, the structure will likely fail, the experts say.
“The containment building at this plant is certainly stronger than that at Chernobyl but a lot less strong than at Three Mile Island, so time will tell,” he said.
Peter Bradford, former member of the US Nuclear Regulatory Commission (NRC), says that if the cooling attempts fail, “at that point it’s a Chernobyl-like situation where you start dumping in sand and cement”.
The two worst nuclear accidents on record are the 1986 Chernobyl disaster in Ukraine, and the partial core meltdown of the Three Mile Island reactor in the US state of Pennsylvania in 1979.
Nuclear plant operator Tokyo Electric Power Co says radiation levels had surpassed the legal limit at its Fukushima No. 1 plant, hit by a blast the previous day.
“If it continues, if they don’t get control of this and… we go from a partial meltdown of the core to a full meltdown, this will be a complete disaster,” said Joseph Cirincione, the head of the Ploughshares Fund.
He said the presence of radioactive cesium in the atmosphere after the plant was vented indicated that a partial meltdown was underway.
“That told the operators that the fuel rods had been exposed, that the water level had dropped below the fuel rods and the fuel rods were starting to burn, releasing cesium,” he said.
Japan’s nuclear safety agency rates the Fukushima accident at four on the International Nuclear Event Scale from 0 to 7. The Three Mile Island accident was rated five, while Chernobyl was a seven.
But World Nuclear Association spokesman Ian Hore-Lacy says the threat of a full meltdown is minimal.
“That possibility is remote at the best of times and is diminishing by the hour as the fuel gets cooler and generates less heat,” he said.