* Officials readying new tactics for Fukushima
* Radioactive water pooled in basement of No. 1 unit
* Update on timetable for stabilising plant due on Tuesday
(Fixes typo in second para)
By Rie Ishiguro and Kevin Krolicki
TOKYO, May 15 Japanese officials are readying a
new approach to stabilising a reactor at a nuclear plant
crippled by an earthquake and tsunami after discovering a leak
from the containment vessel of enough radioactive water to fill
an Olympic swimming pool.
The discovery has forced officials to abandon their original
plan to bring under control the No. 1 reactor at the Fukushimi
Daiichi plant, crippled by the March 11 earthquake and tsunami.
That plan would have entailed cycling a more limited volume of
water across uranium fuel believed to have gone into meltdown.
Despite the setback, Japanese nuclear safety officials and
the plant's operator, Tokyo Electric Power (TEPCO) ,
plan to stick to a target of stabilising the plant and bringing
its reactors to a state of "cold shutdown" by January.
"We want to preserve the timetable, but at the same time
we're going to have to change our approach," Goshi Hosono, an
adviser to Prime Minister Naoto Kan, told a television talk show
Outside experts have questioned whether the initial
timetable for Fukushima was too optimistic. The 9.0 earthquake
and the tsunami that followed unleashed the worst nuclear
accident since Chernobyl in Ukraine in 1986.
Tepco is scheduled to provide an update on progress on
Tuesday. In a pair of television appearances on Sunday, Hosono
said the government would announce its own timetable for
recovery efforts at the same time.
Tepco is preparing to pay compensation to thousands of
residents, farmers, fisherman and businesses for the disaster
under a plan directed and partly funded by the government.
Kan has said Japan's government shares responsibility for
the disaster after promoting nuclear power for decades. A
government study published last December and made public on
Sunday shows that officials had made a detailed analysis of
tsunami risk to nuclear plants. [ID:nL4E7GF003]
Also on Sunday, about 7,800 residents northwest of Fukushima
began a new round of evacuations. The towns are outside the
30-km (18-mile) safety zone set by the government but stood in
the path of the radioactive plume that took shape just after the
The 9.0 magnitude earthquake and ensuing 15-metre
(46.5-foot) tsunami devastated Japan's northeastern coast,
killing more than 15,000 people. A further 9,500 are still
PROBLEMS WITH RADIOACTIVE WATER
The wider evacuations come after worrying details emerged
about the state of the No. 1 reactor last week. Progress to
bring the unit under control has been seen as a test case for
how quickly work on three other damaged reactors can proceed.
Among the revelations: the fuel in the reactor had melted
down after the earthquake and dropped to the bottom of the
pressure vessel at the core. Officials now estimate that the
fuel rods in the No. 1 reactor could have been exposed to the
air for as long as 14 hours after the accident.
A reading taken by a robot on the first floor of the reactor
building on Friday recorded 2,000 millisieverts per hour, a
level permitting workers to stay in the vicinity for no longer
than eight minutes.
In addition, the reactor's containment vessel has leaked
large amounts of the water being piped in to cool the fuel.
On Saturday, a Tepco worker was able to peer into basement
of the reactor building and saw it had filled to almost half its
11-metre (35-foot) height with radioactive water -- an estimated
3,000 tonnes, larger than an Olympic swimming pool.
Critics have said that pumping in large amounts of water --
more than 10,000 tonnes in No. 1 reactor alone -- puts both the
groundwater and nearby Pacific at risk.
"We have a problem to face dealing with the water," Hosono
said. "We have to think of this in terms of a big loop - taking
the water out of the plant, cleaning it and then returning it to
cool the reactor."
That marks a break with the previous plan to use a more
conventional cooling system. Instead, Hidehiko Nishiyama, a
spokesman for the Nuclear and Industrial Safety Agency, said new
steps were being readied to treat and store radioactive water.
Among the major risks ahead, experts say, is the prospect of
another hydrogen explosion like those believed to have destroyed
parts of the buildings housing reactors No. 3 and No. 4.
Workers stepped up the flow of water into the No. 3 reactor
on Saturday after concern about the heat still being generated
by its fuel. Officials also remain worried about the structural
integrity of the building in No. 4 that supports its fuel
storage pool, an area that raised concern among U.S. officials.
(Editing by Ron Popeski)