nuclear-news

Costs and safety problems in Japan’s older nuclear reactors

Six reactors in Japan, including Tsuruga’s unit No. 1, have the same design as those that failed at Fukushima—a General Electric Co. model called Mark I originally designed based on tests from the late 1950s and early 1960s.

In 2009, Chubu Electric Power Co.  based in central Japan, decommissioned the No. 1 and 2 reactors at its Hamaoka nuclear-power plant because they were too expensive to keep up to safety standards.

 Japan Assesses Older Nuclear Plants WSJ,  By MARI IWATA and ELEANOR WARNOCK, May 2, 2012, TOKYO—Japan is grappling with the question of whether older nuclear reactors are more prone to spinning out of control when a disaster hits, as the nation pushes to restart units for the first time since last year’s accident in Fukushima.

The Japanese government, which has held a series of hearings on the
matter this year with an expert panel, concluded age wasn’t a factor
in the meltdown of three reactors at the Fukushima Daiichi plant
following the devastating earthquake and tsunami in March 2011. All
three reactors went online in the 1970s. The government said bolts,
pipes and other important parts used in safety equipment such as
cooling systems had been regularly replaced, making the age of the
reactors less relevant.

A number of critics have expressed concern with the findings, saying
that the government’s investigations weren’t broad enough, and that it
ignored comments even from critical members of the panel……

Although restart decisions are officially up to regulators and plant
operators, the government has said it won’t restart reactors unless it
has the support of local communities.

At the front of the restart queue are two relatively new reactors: the
1990s-built No. 3 and No. 4 units at the Oi plant in western Japan,
according to people familiar with the matter in the government and at
Oi operator Kansai Electric Power Co. 9503.TO -1.22% Two other
reactors that began operation in 1979 at the same plant and were shut
down first for routine maintenance aren’t being considered yet for
restart.

In Fukui prefecture, where Oi is located, eight of 13 nuclear reactors
started commercial operations in the 1970s, including Japan’s oldest
reactor, the 42-year-old unit No. 1 at the Tsuruga nuclear plant.
After the Fukushima accident last year, Fukui Gov. Issei Nishikawa
told reporters that some reactor designs “may be too old” to
withstand natural disasters on par with the quake and tsunami. Mr.
Nishikawa hasn’t commented on the government’s conclusions.

A spokesman for Japan’s nuclear regulator, the Nuclear and Industrial
Safety Agency, said it won’t conduct any more investigations into
whether the age of the Fukushima Daiichi reactors was a factor in that
accident, because the damaged reactors are officially shut down. The
regulator will continue to investigate age fatigue at other plants as
part of its normal duties, he said.
Six reactors in Japan, including Tsuruga’s unit No. 1, have the same
design as those that failed at Fukushima—a General Electric Co. model
called Mark I originally designed based on tests from the late 1950s
and early 1960s….
some experts predict older plants will have a harder time complying
with safety standards, which are constantly being revised and
strengthened.

“Nuclear-power plants built in the 1970s are generally more vulnerable
than newer ones,” said Hiromitsu Ino, a former professor at Tokyo
University who has studied metals used in reactors. He is critical of
the government’s conclusions regarding reactor aging, and says the
government should have looked into more reactor parts and broadened
its investigation to include reactor vessels……
In 2009, Chubu Electric Power Co.  based in central Japan,
decommissioned the No. 1 and 2 reactors at its Hamaoka nuclear-power
plant because they were too expensive to keep up to safety standards.
http://online.wsj.com/article/SB10001424052702303978104577361191820516780.html

May 3, 2012 - Posted by Christina Macpherson | Japan, safety