* Pshakin says Japan should urgently restore power supply
* Graphite burned at Chernobyl, no graphite at Fukushima
* Talk of chain reaction in spent fuel pool groundless
By Gleb Bryanski
MOSCOW, March 17 (Reuters) - Japan should concentrate its efforts on restoring power to the Fukushima nuclear plant rather than trying to cool its reactors by dropping water from helicopters, a Russian nuclear expert said on Thursday.
“One can only put out forest fires like this, by pouring water from helicopters. It is not clear where this water is falling,” Gennady Pshakin from the Institute of Physics and Power Engineering in the city of Obninsk said by telephone.
“They need to start circulation pumps, at least one, maybe not at a full capacity, but I am not sure they have enough power. Diesel generators and mobile power stations which they sent there do not have enough capacity.”
Pshakin said the crisis unfolding after an earthquake crippled reactors at Fukushima was unlikely to become a second Chernobyl, and fears about a chain reaction in the spent fuel pool were groundless.
“It cannot be compared with Chernobyl. We had a totally different situation, a real fire. At Fukushima there is no fire, and nothing to burn, there is no graphite there. Only the spews of steam can take place there,” he said.
“I do not understand why there is such a noise about the fire in the spent fuel pool. There is nothing to burn there.” Japan said the situation in the pool remained a serious concern.
Pshakin said that at Chernobyl, the scene of the world’s worst nuclear accident in 1986, a massive expulsion of heavy radioactive metals such as plutonium and strontium into the atmosphere resulted from the fire and explosions.
He said there was no likelihood of this happening at Fukushima.
“Even if they have a meltdown, it will still only be small particles and steam,” he said. Due to the presence of zirconium it was likely that electrolysis of water could lead to the formation of hydrogen and oxygen.
“Their mixture could result in local explosions if there are sparks or overheating,” he said. He expects the reactors to start cooling within 10 days.
“The picture should clear up within 10 days. Then the self-cooling will reach the point where the remaining water will be enough. But circulation should be fixed in any case,” he said.
Pshakin said that caesium which is being spewed into the atmosphere at Fukoshima has a half-life period of 100 days, and he expects radiation levels to exceed the norm by 3-5 times outside the 30-kilometre zone around Fukushima.
“The level of radiation danger depends on how much the fuel has burnt down and how much caesium has been created. Most of it usually remains in the spent fuel,” he said.