Headway as Fukushima pumps restart
March 21, 2011
ENGINEERS have restored power to cooling pumps in two reactors at the Fukushima No. 1 nuclear power plant, the first genuinely hopeful sign in the battle to prevent a meltdown at any of the six reactors.
Although power has so far been restored only at reactor buildings 5 and 6, which were not considered a particular threat, that success suggests workers are finally beginning to make headway in preventing more radiation from escaping.
Japan's military is also spraying water from fire engines to cool the No.4 reactor, the site of two blazes last week, while pressure in No.3 stabilised as the fight to contain the crisis entered its second week.
The improvement at the No.3 reactor could eliminate the need to vent radioactive steam, Tokyo Electric Power Company spokesman Naoyuki Matsumoto said.
Tokyo Electric said water pumps and controls might still fail to function even with power restored due to damage from the disaster.
Reactors 5 and 6 had been shut down at the time the quake struck on March 11, but spent fuel rods in an upper level of the reactor buildings were still generating heat and required cooling. When electricity was lost and the tsunami damaged back-up generators, the pools holding the fuel rods began to grow warmer.
Officials of Tokyo Electric said temperatures in the No.5 and No.6 pools had begun to fall since the pumps restarted.
Police and military teams were spraying water manually on the other buildings to keep the reactor cores and the spent fuel pools cooled and prevent a meltdown that would release large amounts of radiation.
The most recent reports suggest that the heavy spraying is working and has reduced radiation levels at the plant.
Engineers had run a power line to the plant, 240 kilometres north of Tokyo, from the country's electrical grid on Friday night, but connecting it has been a bigger problem than anticipated. Workers could only spend limited amounts of time in the plant to make the connections, and engineers have had to laboriously check all the circuitry first to ensure there was no surge of current.
Engineers have been focusing on reactors No.2 and 3 and the building housing reactor No.4. But the need to build shelters to protect workers and equipment from the spray water, as well as from the radiation, delayed efforts.
Reactor No.2 is thought to have a cracked containment vessel and is potentially the most problematic reactor. Reactor No.3 is not known to be damaged, but its fuel rods contain a mixture of uranium and highly carcinogenic plutonium. Even a leak of small quantities would be disastrous.
The pool at reactor No.4 has the hottest spent fuel and is thought to have either holes in the pool or another leak that is allowing water to run out. It is thus imperative to cool those heat sources first.
Japan now says the tsunami-ravaged nuclear plant must eventually be scrapped.
Closing the plant is inevitable since the seawater that emergency crews are using to cool the reactors is corrosive, rendering critical parts of the complex unusable.
Chief Cabinet Secretary Yukio Edano has also revealed ''abnormal levels'' of radiation have again been detected in milk and spinach taken from areas near the plant. It's the second such announcement in as many days and is certain to fuel public anxiety. smh.com.au |
