Plutonium found in soil at the Fukushima nuclear complex heightened alarm on Tuesday over Japan’s battle to contain the world’s worst atomic crisis in 25 years, as pressure mounted on the prime minister to widen an evacuation zone around the plant.Some opposition lawmakers blasted Naoto Kan in parliament for his handling of the disaster and for not widening the exclusion zone. Kan said he was seeking advice on such a step, which would force 130,000 people to move in addition to 70,000 already displaced.
Plant operator Tokyo Electric Power Co said plutonium was found at low-risk levels in five places at the facility, which was crippled by a massive earthquake and tsunami on March 11.
A by-product of atomic reactions and also used in nuclear bombs, plutonium is highly carcinogenic and one of the most dangerous substances on the planet, experts say.
They believe some of the plutonium may have come from spent fuel rods at Fukushima or damage to reactor No. 3, the only one to use plutonium in its fuel mix.
Japan’s Nuclear and Industrial Safety Agency said while the plutonium levels were not harmful to human health, the discovery could mean the reactor’s containment mechanism had been breached.
“Plutonium is a substance that’s emitted when the temperature is high, and it’s also heavy and so does not leak out easily,” agency deputy director Hidehiko Nishiyama told a news conference.
“So if plutonium has emerged from the reactor, that tells us something about the damage to the fuel. And if it has breached the original containment system, it underlines the gravity and seriousness of this accident.”
Sakae Muto, a Tokyo Electric vice-president, said the traces of plutonium-238, 239 and 240 were in keeping with levels found in Japan in the past due to particles in the atmosphere from nuclear testing abroad.
“I apologise for making people worried,” Muto said.
Workers at Fukushima may have to struggle for weeks or months under extremely dangerous conditions to re-start cooling systems vital to control the reactors and avert total meltdown.
On Monday, highly contaminated water was found in concrete tunnels extending beyond one reactor, while at the weekend radiation hit 100,000 times over normal in water inside another.
That poses a major dilemma for Tokyo Electric, which wants to douse the reactors to cool them, but not worsen the radiation spread, Chief Cabinet Secretary Yukio Edano said on Tuesday.
“On the issue of pumping in water, we must avoid a situation in which the temperature (of the fuel rods) rises and the water boils off.
So this cooling is a priority. On the other hand, on the standing water, under the circumstances work must proceed to remove it as quickly as possible,” he said.