Workers Seal Off Damaged Japanese Nuclear Plant Reactor Employees Delayed Reporting Fire, Explosion While They Waited For Orders

Workers sealed off a damaged nuclear plant Thursday, and the company that runs the plant admitted that employees delayed reporting both a fire and a later explosion for 30 minutes while they waited for orders.

The cause of Tuesday’s fire at the plant in Tokaimura, northeastern Japan, is still not known. The fire apparently led to the explosion 10 hours later in a waste-handling facility.

But the person with sole authority to make emergency decisions apparently was on vacation Tuesday, and TV reports Thursday indicated a slow, inflexible response compounded the damage and the release of low-level radioactivity.

The incident exposed at least 37 workers to small amounts of radiation - one-2000th of the dose considered safe for a year, according to the plant. It was the most workers ever exposed in a nuclear accident in Japan.

Public broadcaster NHK cited investigators as saying the radiation leak and possibly the blast may have been caused by a gradual increase in air pressure because heat from the fire disabled the building’s ventilation and pressure equalization systems.

In a similar report, the Asahi Television network said the plant’s operator knew immediately after the explosion that minuscule amounts of radiation had been released, but omitted that fact from statements that day.

NHK also said officials, mistakenly thinking the fire was out, neglected to check the temperature in the room where the fire originated. The fire eventually spread and apparently triggered the explosion.

Workers clad in protective suits with breathing filters used duct tape Thursday to seal 30 windows and three doors damaged by Tuesday night’s blast.

A spokesman for the plant’s government-linked operator, the Power Reactor and Nuclear Fuel Development Corp., or Donen, said sole authority to make emergency decisions rested with the chief of the plant, who was on vacation Tuesday. The only people working at the site when the initial fire broke out at 10 a.m. were employees of a subcontractor that runs the plant.

After discovering the fire, those workers waited for orders from officials in another building and four minutes elapsed before the sprinkler system was turned on, he said.

Employees then waited more than 30 minutes before contacting the local fire department, the spokesman said.

Ten hours later, the explosion occurred. Donen employees again delayed notifying the fire department for more than 30 minutes, he added.

The accident occurred just as Japan’s government was trying to rebuild trust in its nuclear program, set back by an accident in December 1995 in a prototype fast-breeder reactor.