[NYTr] Japan: Nuclear Power on Shaky Ground

[nytr at olm.blythe-systems.com]

sent by Dave Muller (southnews)

The Yomiuri Shimbun - Jul 23, 2007
http://www.yomiuri.co.jp/dy/national/20070723TDY01002.htm

NUCLEAR POWER ON SHAKY GROUND

No price too high to pay for safe nuclear plants


This is the second installment of a three-part series examining how 
earthquake-prone Japan can coexist with nuclear power plants, a concern 
that has surfaced in the wake of the July 16 earthquake in the Chuetsu 
region of Niigata Prefecture--the first temblor anywhere in which a 
fault line ran beneath a nuclear power plant.

Following last Monday's earthquake, the asphalt-paved grounds of Tokyo 
Electric Power Co.'s Kashiwazaki-Kariwa nuclear power plant in Niigata 
Prefecture bulge and sag, blocking people's path.

Immediately after the Niigata Prefecture Chuetsu Offshore Earthquake 
occurred, Shizuo Suda, deputy manager of the fire prevention division
at Kashiwazaki Fire Department, entered the plant to inspect an
electric transformer that had caught fire. After observing the scene,
Suda became very concerned about the possibility of a secondary
disaster occurring. He had never imagined that an earthquake would
bring about such terrible destruction, and he thought to himself that
if oil leaked from an underground pipe and ignited, there would be no
remedying the situation.

Suda's report to the Kashiwazaki municipal government indicating the 
seriousness of the situation at the plant prompted the municipal 
government to issue an emergency order to TEPCO instructing it to shut 
down the plant.

Yumio Ishii, president of the Japan Society of Civil Engineers, said 
Friday: "I strongly feel we were lucky the disaster wasn't worse than
it was. The quake-resistance standards for nuclear power plants
definitely need to be reviewed."

The late Nobu Kitamura, a prominent geologist and professor emeritus at 
Tohoku University, conducted research into faults across the country in 
the 1960s and '70s. He once described the Japanese archipelago, which
is situated in a seismogenic zone, as follows: "If I throw a stone from 
here to there, countless faults lie underground in the space between. 
That's where Japan is located."

Last Monday's quake, in which fault lines directly underneath the 
nuclear power plant shifted, showed Kitamura's description was no 
exaggeration.

Japan is the only country located on four plates edging toward each 
other and many fault zones. Among 31 nations and regions that have 
nuclear power plants, Japan is the most at risk of being hit by 
earthquakes. Japan introduced nuclear power technology from Europe and 
the United States 50 years ago. The history of Japan's nuclear power 
industry has been a struggle against earthquakes.

Inside a nuclear reactor, control rods designed to serve as brakes move 
between nuclear fuel rods that are assembled precisely spaced apart.

If the spacing changes even slightly due to an earthquake, the control 
rods will cease to function as brakes.

Japan Atomic Power Co.'s Tokai nuclear power station in Tokaimura, 
Ibaraki Prefecture, is the nation's first commercial nuclear power 
plant. A graphite reactor, imported from Britain, a nation that not
face the threat of serious earthquakes, was used for the power plant.

At the time of introducing the reactor, questions regarding its 
quake-resistance capabilities were voiced by many experts, forcing the 
company to make changes in the construction plan, including
improvements to the graphite layers surrounding the fuel rods.

The technology for light water reactors, which was used in many plants 
later, was imported from the United States, which has seismogenic zones 
on its Pacific Coast.

Although those reactors were designed for optimum quake resistance, the 
United States is blessed with many choices for locating its nuclear 
plants, so it does not have to worry so much about making its nuclear 
plants capable of withstanding very strong quakes.

Japan, however, had to develop the strictest quake-resistant standards 
for its nuclear power plants. But the tremors of the Niigata Prefecture 
Chuetsu Offshore Earthquake exceeded those standards.

Seismic research has advanced significantly in the past half century. 
But it was only after the Great Hanshin Earthquake in 1995 that active 
faults in various regions earned serious attention. Also, it was not 
until the 1980s that understanding of the process of liquefaction began 
to deepen.

Seismology is still developing, and quake-resistance standards for 
nuclear power plants always need to be reviewed.

It is said that the cost of building one nuclear power plant in Japan
is 300 billion yen--the highest in the world--as expenses for 
quake-resistance measures are high.

In the electric power industry, many are reluctant to adopt strict 
antiseismic measures, saying costs will skyrocket if standards are made 
rigorous.

Mitsumasa Hirano, chief secretary of the Japan Nuclear Energy Safety 
Organization said, "People have become to understand the uncertainty of 
seismology, and the social perception toward risk has changed since the 
Great Hanshin Earthquake."

Electric power companies have been making efforts to balance cost and 
safety in setting quake-resistance standards for nuclear power plants, 
but it is not acceptable to delay the implementation of antiseismic 
measures simply because doing so will be expensive.