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Study: December Accident Could Have Triggered Hydrogen Explosion

June 11, 1996

TOKYO (AP) _ A lab reenactment of last December’s nuclear power plant accident showed that a similar failure could escalate into a possible explosion, a utility spokesman said today.

A spokesman for the Nuclear Reactor and Power Development Corp., which runs the reactor and conducted the test, said researchers could not yet explain why the test ended in the possible explosion and the accident itself did not.

A sodium coolant, believed to have corroded the pipes it was traveling through, leaked Dec. 8 from the Monju nuclear reactor in Tsuruga, 220 miles west of Tokyo.

There were no injuries. The reactor was shut down and has not been reactivated since.

In laboratory tests last week, spilt sodium ate through steel plates similar to those used on the reactor’s floor, according to utility spokesman Kazushige Kikuchi.

If that had created the holes, allowing the sodium to flow down to the concrete lying below, an explosion would have theoretically followed, Kikuchi said.

``We need to find why the holes opened during the experiment but not during the accident,″ Kikuchi said.

Anti-nuclear activists said it was impossible to determine how large the explosion could have been, but claimed the surrounding area was in considerable danger.

The power plant at Tsuruga, called Monju for a Buddhist deity of wisdom, is a controversial fast-breeder reactor that uses plutonium, one of the deadliest substances known to man. The plutonium in its core is cooled down with the extremely volatile sodium.

The by-product can be used to create nuclear weapons.

Last week, an official with Japan’s Ministry of International Trade and Industry said the country’s plan to promote a fast-breeder reactor will be reviewed as a result of the accident.

Japan’s Nuclear Safety Commission says an investigation is still under way to determine the exact cause of the accident.

Other industrialized nations, including the United States, Britain and Germany, have given up plans for such reactors because of the costs and the danger.

Update hourly