At least eight people died in the quake that leveled houses, tore apart roads and buckled seaside bridges. Eyewitnesses reported that flames and smoke billowed from the Kazhiwazaki-Kariwa nuclear power plant (NPP) as the result a fire in an electrical transformer that took two hours to extinguish, according to Motoyasu Tamaki, an official with Tokyo Electric Company.

The Kazhiwazaki-Kariwa NPP is the largest nuclear power plant in the world, with an output of 8,212 megawatts, or enough to supply 12 million households. By comparison, the largest US nuclear power facility, in Palo Verde, Arizona, has an output capacity of 3,880 megawatts, according to the US Nuclear Energy Institute.

Owned and operated by Tokyo Electric, the plant Kazhiwazaki-Kariwa runs five boiling water reactors (BWRs) and two advanced boiling water reactors (ABWRs). Three of the BWRs and one of the ABWRs – units 2,3,4 and 7 – shut down immediately after the quake. The number 6 unit, also an ABWR, had already been shut down for repairs and is thought to be the source of the radioactive water leak. Units 5 and 6 where also down for inspection and unit two was being powered up at the time of the quake. The fire was sparked in a transformer linked to another unit, No.3, Tokyo Electric said.

Radioactive damage unclear
The Associated Press quoted an official with Tokyo Electric as saying that unit number 6 leaked some 1190 litres of water. Reuters, however, reported that Tokyo Electric had indicated that only some 1.5 litres of radioactive liquid had leaked from the shut down Unit No. 6. Units 1 and 4 were also not operating when the quake hit. Tokyo Electric officials reached for further comment by Bellona Web confirmed 1.5 liters had leaked from Unit No. 6. The Japanese nuclear NGO, the Citizens’ Nuclear Information Center, reported that some 60,000 Bequerels of radioactivity had ecsaped in the water, meaning there should be no significant impact on the environment.

Katsuya Uchino of Tokyo Electric indicated that the water contained a “tiny” amount of radioactive material and is thought to have been flushed out into the Sea of Japan.

“The radioactivity is one-billionth of the legal limit,” Uchino told Bellona Web, though could not indicate what sort of liquid had escaped or how radioactive it is.

The quake, which left fissures 3 feet wide in the ground along the coast, hit shortly after 10 a.m. local time and was centered off Niigata state. Buildings swayed 160 miles away in Tokyo. Sirens wailed in Kashiwazaki, a city of about 90,000, which appeared to be hardest hit, Japanese government officials said.

Japan’s Meteorological Agency measured the quake at a 6.8 magnitude. Near midnight Monday, another 6.8-magnitude quake hit off Japan’s west coast, according to the US Geological Survey, which said the initial quake registered 6.7.

Radioactive impact insignificant – but fresh fears of nuke power abound
Tokyo Electric told AP that the water leak had stopped and that there had been no "significant change" in the seawater under surveillance and no effect on the environment, but the developments at Kashiwazaki triggered fresh concern about the earthquake resistance of Japan’s nuclear power plants, which supply nearly a third of the country’s electricity.

Aileen Mioko Smith, of the environmentalist group Green Action, told AP that the fire showed that some facilities at nuclear power plants such as electrical transformers were built to lower quake-resistance levels than other equipment such as reactor cores.

"That’s the Achilles heel of nuclear power plants," said Mioko Smith, who confirmed that it took the plant two hours to extinguish the fire. "Today’s a good example of that… How prepared are they to put out fires when they happen?

Russian environmentalists fear nuclear power in Russia Far East
The quake also raises fears in Russian environmental circles, which report that Moscow intends to build a number of nuclear reactors in Russia’s far east off the coast of Japan.

“The appropriate question is how justified is the decision to allow the construction of an atomic power station in a seismically dangerous zone? And how does this relate to the recently forwarded idea to build a nuclear power plant in the Russian far east? “wrote Russian nuclear physicist and environmental commentator Andrei Ozharovsky.

“Maybe the more reasonable course is to not build dangerous nuclear power plants and use alternative energy instead.”

Bigger quakes predicted for Japan
Japan sits atop four tectonic plates and is one of the world’s most earthquake-prone countries. The last major quake to hit the capital, Tokyo, killed some 142,000 people in 1923, and experts say the capital has a 90 percent chance of suffering a major quake in the next 50 years.

Tokyo Electric could not say when the three units that had tripped offline after the quake would be restarted, but an official said it had no immediate plans to increase operations at oil- or gas-fired power plants to make up for the lost capacity.

"We have plenty of power supplies to cover needs for this week between Tuesday and Sunday," another company official said. "We’ll study the situation closely to decide on our plans beyond next week."

The outage comes at a time when Japan’s nuclear sector, which generates about a third of its power, is already operating at unusually low levels for the peak demand summer period, Reuters reported.

Nuclear plants at the country’s 10 generators operated at an average 62.4 percent in June, up from a seven-month low of 61.9 percent in May, data by the Federation of Electric Power Companies of Japan showed last week, according to Reuters.

But it was 7.5 percentage point lower than in June 2006, while overall power consumption rose to its highest on record for the month.

A new batch of safety lapses revealed this year has forced power companies to shut for additional checks this spring, dragging down utilisation rates to their lowest in over two and a half years in May.