* Reactor leaks 8 tonnes of water but none escapes outside
* Incident follows smaller leaks last weekend
* Timing bad as govt seeks consensus to restart reactors
* Tepco stabilising reactors so it can start dismantling
(Adds specialist comment, details, background)
TOKYO, Feb 2 More than 8 tonnes
of radioactive water leaked from a reactor at Japan's Fukushima
nuclear plant but none reached outside the reactor building,
Tokyo Electric Power Co said on Thursday as it strives
to ensure damaged reactors are stable enough for work to start
on dismantling them.
Experts said the incident, which follows smaller leaks last
weekend, is not a big setback to getting the plant under control
but the timing is awkward for the government as it strives to
win public acceptance for the restart of reactors elsewhere to
avoid a summer power crunch.
The Fukushima Daiichi plant, on the coast 240 km (150 miles)
northeast of Tokyo, was wrecked by the March 11 earthquake and
tsunami, triggering reactor meltdowns and radiation leaks that
caused mass evacuations and widespread contamination.
The leak discovered late on Tuesday was from a pipe at the
plant's No.4 reactor that may have burst after freezing due to
cold weather, said a spokesman for the utility, known as Tepco.
He said leaking water would go into a drain leading to a storage
It contained only a tiny amount of radiation compared with
the huge amount of water used to cool the reactors in the
aftermath of the March disaster, much of which is still being
treated at the plant to lower its radiation level, he said.
The No.4 reactor was shut for maintenance when the tsunami
struck, and no fuel rods are inside the reactor vessel.
"I wouldn't say this is a positive development. But it isn't
something that would further stoke safety concerns over other
nuclear plants," said Kenji Sumita, honorary professor at Osaka
"If it hadn't been for the Fukushima disaster, an incident
like this could have gone unreported."
Shattered trust in the safety of nuclear energy has
prevented the restart of reactors shut for routine maintenance,
straining power supply and threatening blackouts. Only three of
Japan's 54 nuclear reactors are now operating. Without approval
for restarts, all of them could be shut by the end of April,
boosting the use of fossil fuels and adding over $30 billion a
year to the nation's energy costs, a government estimate said.
U.N. nuclear experts gave their backing on Tuesday to stress
tests aimed at showing Japan's nuclear plants can withstand the
sort of disasters that devastated Fukushima Daiichi.
The government announced on Dec. 16 that reactors at the
plant had reached a state of cold shutdown, a milestone in
cleanup efforts and a pre-condition for allowing about 80,000
residents evacuated from a 20-km (12 miles) radius of the
Daiichi plant to return home.
Resource-poor Japan had aimed to increase the share of
nuclear power to more than half of its electricity supply by
2030 before the disaster, but now looks to reduce its reliance
on nuclear power and raise the role renewable sources such as
wind and solar power.
Tepco initially estimated the size of this week's leak at
six litres but later revised it to 8.5 cubic metres, and is
looking into how it can prevent similar incidents.
It follows the discovery and plugging of smaller leaks at
the same reactor last weekend.
(Reporting by Mark Bendeich and Kiyoshi Takenaka; Editing by