Japan, UN, to Probe Earthquake Damage at Nuclear Power Plant

TOKYO, Japan, July 24, 2007 (ENS) - Japan will establish an independent committee to investigate leaks of radioactive water, flooding, fire and electrical problems at the world's largest nuclear power plant that was damaged by a strong earthquake July 16, the government said today.

The Tokyo Electic Power Company's Kashiwazaki-Kariwa nuclear power plant in Niigata prefecture was shut down after the 6.8 magnitude quake caused a leak of low-level radioactive water.

Tokyo Electic Power Company's Kashiwazaki-Kariwa nuclear power plant (Photo courtesy TEPCO)

Today, three of the plant's seven units are operating and one is starting up, the company said.

Minister of Economy, Trade and Industry Akira Amari said only that the panel will begin its investigations as soon as possible.

The panel is likely to submit its report to the UN's International Atomic Energy Agency, IAEA, at its annual conference in Vienna in September.

Japan now says it will allow IAEA investigators to inspect the nuclear plant, after an offer of assistance last week from IAEA head Dr. Mohamed ElBaradei.

The government of Shinzo Abe had rejected help from the UN agency, but was persuaded by a petition from local officials eager for more information.

The IAEA said last week that preliminary data indicates that the earthquake "may have exceeded the seismic design assumptions for the plant."

"The agency believes a thorough investigation of the impact of the earthquake on the plant and full transparency in such investigations is required," the IAEA said.

The Tokyo Electic Power Company confirmed today that 2,000 tons of water flooded the basement of the building that houses the facility's No. 1 reactor.

The water escaped from damaged fire protection system piping in Unit 1, the company said, but it was not radioactive.

The leak had been announced in the days following the quake, and today company spokesman Kiyoto Ishikawa said the flooding posed no environmental hazards.

It now appears that the earthquake also shook a storage pool containing about 2,300 kiloliters of water and spent nuclear fuel on the fourth floor of the No. 6 reactor building, TEPCO said.

The radioactive water spilled through a small hole where electric cables run through for equipment used to transport spent fuel, TEPCO said.

Usually, insulation material fills the spaces between the hole and the cables, but the packing material evidently came loose during the quake, allowing the water to flow along the cables and then into an air conditioning duct before entering drainage ditches that lead to the Sea of Japan, TEPCO said.

The floor where the storage pool is located is in a restricted radiation zone, but the floors into which the water flowed are outside the restricted zone, the utility said.

An estimated 1.2 cubic meters of radioactive water flowed into the sea, but the company said it is still not certain about the total amount of water that flowed from the pool.

TEPCO says that during the incident, radioactive material was twice vented into the air.

TEPCO has started on repairs of minor damage at the plant, and the company will soon prepare a plan for the detailed check of safety-significant equipment such as the reactor internals, said the Nuclear and Industrial Safety Agency. A detailed inspection of the reactors will be conducted based on that plan.

Minister Amari acknowledged today that the government failed to carefully examine fault lines near nuclear power plants, and said a stricter review system is needed, the Kyodo news agency reported.

The 6.8 magnitude earthquake that claimed 11 lives was located in the city of Kashiwazaki and the village of Kariwa along the Sea of Japan coast.

With a combined power output capacity of more than 8,200 megawatts, the Kashiwazaki-Kariwa nuclear power plant is the world largest. The quake's epicenter was just 16 kilometers, 10 miles, away from the plant.

Copyright Environment News Service (ENS) 2007. All rights reserved.