By IANS,
Tokyo: Japanese government said Saturday condition at four reactors at the quake-hit Fukushima nuclear power plant were improving.
Following Japan’s Self-Defence Force (SDF) and firefighting personnel shooting water over Fukushima’s nuclear reactor 3 Saturday afternoon, to cool down the reactor and overheating spent fuel pools, Defence Minister Toshimi Kitazawa said the operation had been successful.
The situation at the reactor 1 to 4 was “more stable than expected” as the temperature of the four reactors at the plant remained below 100 degrees Celsius, Xinhua quoted Kitazawa as saying during a press conference Saturday.
As per experts, a rise in water temperature, usually to 40 degrees Celsius, causes the water-level in the fuel pools to fall, exposing the spent nuclear fuel rods, which could then heat up further, melt and discharge highly radioactive materials in the worst-case scenario.
Japanese Prime Minister Naoto Kan, however, has directed Kitazawa for a close monitoring of the situation.
Chief Cabinet Secretary Yukio Edano has said that whilst stations at the Fukushima plant remain unpredictable, he believes water-spraying over the spent fuel rod pool in the reactor 3 is successful and that the current situation is “more stable than before”.
“We are trying to get things under control,” Edano said, adding that the SDF was now preparing to spray water into the reactor 4 to cool its spent fuel pool.
Earlier Saturday, Japan’s Meteorological Agency announced that a strong earthquake of magnitude 6.1 jolted Ibaraki Prefecture and the surrounding area in the Kanto and Tohoku region at 6.56 p.m. (local time) Saturday evening. But no damage to nuclear facilities in Ibaraki, or Tohoku Prefecture were recorded.
An unmanned vehicle with a 22-metre high platform was used to avoid personnel coming into contact with excessive amounts of radiation.
The Tokyo Fire Department’s special “hyper rescue team” also joined the SDF in spraying water to cool down the nuclear reactor 3. The combined effort discharged 60 tonnes of water within 20 minutes in the operation’s first phase Saturday morning.
Efforts to cool the reactor were suspended Saturday morning, as TEPCO workers tried to reconnect electricity to the plant using outside power sources.
TEPCO said that reconnection of the nuclear reactor 2 was expected to be completed during the day. But it might take some time before cooling devices could be reactivated, as a lot of damage might have been caused to electrical systems of the Fukushima nuclear plant due to the March 11 magnitude 9 quake and ensuing tsunami.
The utility said that at the time of the quake, the reactors 1, 2 and 3 of Fukushima nuclear plant were the only ones operating and shutdown automatically, as they are supposed to. But due to lost cooling functions in the reactors some of the cores are believed to have partially melted.
The buildings housing the reactor 1, 3 and 4 have been severely damaged, and fuel pools in the reactors have been left uncovered. In addition, the reactor 2’s containment vessel suffered damage to its pressure-suppression chamber, TEPCO said.
TEPCO said that post-operation readings taken as of 2.50 p.m. (local time) Friday stood at 3,339 microsieverts per hour, compared to 3,484 microsieverts at 1.50 p.m., before the work started.
The government has set an exclusion zone covering areas within a 20-km radius of the plant and has urged people within 20 to 30 km to stay indoors.
The Nuclear and Industry Safety Agency raised the severity level of the crisis-hit reactors to 5 from 4 on an international scale Friday.
Chief Cabinet Secretary Yukio Edano said earlier that higher levels of radiation than the legal standard were detected in fresh milk and spinach in Fukushima Prefecture.
According to media reports, 7,320 people have been killed in the tsunami and earthquake. At least 11,370 people were still unaccounted for. Hundreds of thousands are still living in makeshift shelters and camps.