TEPCO struggles to resume key water treatment system at Fukushima
TOKYO (Kyodo) — Tokyo Electric Power Co. continued struggling Monday to
figure out how to cope with difficulties in operating a newly installed
water treatment system at its troubled Fukushima Daiichi nuclear power
plant, aiming to resume its full operation as early as Tuesday.
Smooth operation of the system, which is designed to remove highly
radioactive materials from a massive amount of water accumulating at the
station, is considered essential to containing the three-month-old
nuclear crisis, as the utility plans to eventually recycle the water to
cool the plant’s damaged reactors.
But the newly installed system was halted at 12:54 a.m. Saturday, after
becoming fully operational at 8 p.m. Friday, because the radiation level
of a component to absorb cesium had reached its limit and required
replacement earlier than expected, the plant operator said.
The utility, known as TEPCO, has been analyzing why the component has
not worked well and how to solve the problem, the firm’s officials said.
’’I think we can resume operating the system in a day or so,’’ TEPCO
spokesman Junichi Matsumoto said at a press conference, emphasizing that
it will not take a long time before the company will come up with
measures to decontaminate high-level radioactive water.
While dealing with the tainted water, TEPCO said Monday it fully opened
the doors of the No. 2 reactor building at the power station to lower
humidity inside to enable people to work there, denying the move would
have an impact on the environment.
The ventilation has helped reduce the humidity inside, the government’s
nuclear safety agency said, adding that the level declined to 58.7-89.9
percent from as high as 99.9 percent measured before the doors were opened.
If the level of humidity decreases to around 70 percent, people can work
inside the building with full-face masks, which could allow TEPCO to
start injecting nitrogen into the reactor to prevent a hydrogen
explosion and adjust measuring equipment there, the Nuclear and
Industrial Safety Agency said.
In other progress, a robot called ’’Quince’’ — jointly developed by
Japan’s Chiba Institute of Technology, Tohoku University and other
institutions — will be sent to the Fukushima power complex, the agency
said.
Quince is capable of operating in places where rubble is scattered and
is believed to be able to measure levels of radiation inside buildings
and depths of contaminated water, as well as obtain samples of such
water, as it can climb wet and slippery steps, the agency added.
Still, TEPCO also said Monday that one more worker involved in efforts
to tackle the nuclear crisis at the power station was found to have been
exposed to radiation above the maximum allowable limit of 250
millisieverts, bringing the total number of such workers to nine.
The latest announcement was made as the utility is checking the external
and internal radiation exposure of a total of more than 3,500 workers
who were engaged in the emergency work in March, after the devastating
March 11 earthquake and ensuing tsunami crippled the plant.
The government will ’’have the responsibility to implement thorough
measures’’ to prevent workers at the complex from being excessively
exposed to radiation, Goshi Hosono, a special adviser to Prime Minister
Naoto Kan on the handling of the nuclear disaster, said at a press
conference.
Mainichi Shimbun , June 20, 2011
http://mdn.mainichi.jp/mdnnews/national/news/20110620p2g00m0dm090000c.html
N-bldg cover to be built, unbuilt, rebuilt
IWAKI, Fukushima—Work to assemble parts of a giant cover for the No. 1
nuclear reactor building at Tokyo Electric Power Co.’s Fukushima No. 1
nuclear power plant is proceeding at a fever pitch at Onahama Port in
Iwaki, Fukushima Prefecture.
The giant cover is designed to prevent most radioactive substances from
dispersing into the atmosphere from the No. 1 reactor, which was damaged
by a hydrogen explosion on March 12.
It will enclose an area of 42 meters by 47 meters and will stand 54
meters high.
To limit workers’ exposure to radiation and shorten the construction
period, 62 parts, including pillars, beams and polyester-sheeted panels,
are being assembled at the port into a unified structure. After it is
confirmed that the parts fit together properly, the cover will be
disassembled and transported to the nuclear power plant by ship.
On-site assembly of the components is scheduled to start next Monday.
TEPCO plans to complete the work in late September.
Final construction of the cover will be carried out by two giant cranes,
which will be remote-controlled.
A traditional Japanese insertion-only joint method, which does not
employ welding or bolts for joining materials, is being used to assemble
the cover.
The Yomiuri Shimbun , June 21, 2011
http://www.yomiuri.co.jp/dy/national/T110620004790.htm
TEPCO Builds Pillars to Support Fukushima No. 4 Reactor Pool
Fukushima, June 20 (Jiji Press)—Tokyo Electric Power Co. said Monday
it has finished building pillars to support the bottom of the spent fuel
pool of the No. 4 reactor at the Fukushima No. 1 nuclear power plant.
The power firm will boost the load tolerance of the pool by
reinforcing the facility with more concrete by the end of July, TEPCO
officials said.
The building that houses the No. 4 reactor sustained major damage in
what appears to have been a hydrogen explosion in March.
An analysis shows the quake resistance of the building is almost
intact, but TEPCO is conducting reinforcement work to keep on the safe
side, the officials said.
In the work, TEPCO built 32 steel pillars to support the pool’s
bottom. Each pillar can withstand weights of up to 40 tons.
Jiji Press, June 20, 2011
http://jen.jiji.com/jc/eng?g=eco&k=2011062000882
Tepco airs out humid reactor No. 2 building
Tokyo Electric Power Co. on Sunday released air from a reactor building at its crippled Fukushima No. 1 power plant, possibly allowing low-level radioactive substances to escape into the environment.
Tepco said that it opened the doors of reactor 2 at 8:50 p.m. to lower the humidity inside so people can work there. The utility claimed the move would not harm the environment.
The humidity in the damaged unit is nearly 100 percent, which is hampering efforts to bring the stricken plant under control. The utility plans to open the doors slowly and gradually in an operation that will last until around 4 a.m. Monday to avoid stirring up dust containing toxic materials.
After the venting, Tepco will start injecting nitrogen into the reactor to prevent a hydrogen explosion, and also adjust measuring equipment, it said.
A week ago, Tepco said it began filtered venting of the No. 2 reactor building to lower radiation levels to the point where workers can go inside. The high radioactivity and humidity have prevented workers from checking gauges and pipes, hampering efforts to cool the reactor.
Meanwhile, a piece of highly radioactive equipment that was removed from a separate reactor before the disaster and stored under water may be emitting radiation air after becoming partly exposed, Tepco said Sunday.
Although radiation levels are not unusually high around unit 4, which had been suspended for regular inspections when the March 11 tsunami knocked out its cooling systems, the equipment in question is not specifically monitored and requires radiation precautions be taken when work is required at the site.
Reactor 4 was not loaded with fuel when the quake hit, but it did have spent fuel rods cooling in a storage pool above it. But since the pool can’t be automatically cooled anymore, the still-hot rods are causing evaporation, which is drying up an adjacent pit. That pit contains a shroud that was used to adjust the flow of water inside the building. The 7.6-meter-deep pit contains just 2.5 meters of water, Tepco said, indicating that the hot part of the shroud, which was originally 6.8 meters high but was cut to fit in the pit, may be exposed to air.
Kyodo, June 20, 2011
http://search.japantimes.co.jp/cgi-bin/nn20110620a1.html