Japan had some success cooling reactors at the crippled Fukushima Dai-Ichi plant, bringing two of the six reactors under control and connecting a second electric cable to the station, according to reports.
Tokyo Electric Power Co., the operator, declared Units 5 and 6 safe after cooling water pumped into them reduced temperatures. An electric cable was hooked up to the No. 5 reactor, Kyodo News said, citing Tepco.
U.S. Energy Secretary Steven Chu said the Obama administration believes the worst of the crisis is over. Unit 2, where Tepco connected a 1.5-kilometer (1 mile) power cable March 18 as it tried to revive cooling systems knocked out by the magnitude-9 temblor and tsunami, is the main source of concern, Chu said on CNN’s “State of the Union” program.
“Because of the higher levels of radiation there, we take that as evidence that there might be a breach in that containment vessel,” he said. “But they’re not extraordinarily high, so it appears if there is a breach, it would be a limited breach. But, again, we don’t really know.”
The International Atomic Energy Agency’s 35-member board of governors will convene an extraordinary meeting today for the first time since Dec. 2009 when Director General Yukiya Amano was voted into his post. Amano will report on his March 19 meeting with Japanese Prime Minister Naoto Kan and senior nuclear officials.
Radiation measured in Tokyo, 220 kilometers (140 miles) south of Fukushima, declined marginally yesterday, to 0.0480 microgray per hour between 3 p.m. and 4 p.m. local time yesterday. In Kitaibaraki City, located between Tokyo and the damaged plant, radiation was at 0.783 at 3 p.m., down from readings above 1 microgray on March 18. An x-ray typically has 50 micrograys of radiation.
Shifting winds and rain will carry radiation released from the Fukushima complex inland and deposit radionuclides on the ground, Austria’s Meteorological and Geophysics Center reported yesterday, citing United Nations data.
“From the point of view of the worst-case scenario, the largest emissions are behind us and they went out to the Pacific Ocean,” Sergei Kiriyenko, head of Russia’s state nuclear power company, Rosatom Corp., said on Russian state TV Vesti. He said there may continue to be periodic emissions.
Japan’s military sprayed water from fire engines to cool the Fukushima Dai-Ichi No. 4 reactor, the site of two blazes last week. Pressure in No. 3, which spiked earlier, has stabilized, Chief Cabinet Secretary Yukio Edano said in Tokyo yesterday.
Tepco considered venting radioactive steam from the reactor yesterday before it stabilized, said Naoyuki Matsumoto, a company spokesman.
Tepco is still working on getting power fully restored after connecting the cable to Unit 2, Matsumoto said by phone late yesterday. Water pumps and controls may still fail to function once power is back if they’ve been damaged. A successful hook-up would advance efforts to prevent a meltdown.
If fuel rods in the plant have been damaged, the reactor cores may be more difficult to cool after power is restored, Edwin Lyman, a physicist with the Union of Concerned Scientists, said on a conference call.
Efforts to contain the crisis have been hampered by radiation that made it hazardous for workers to spend prolonged periods in the immediate vicinity of damaged buildings. Soldiers from Japan’s Self Defense Force and firefighters from Tokyo have used water cannons, specialized fire equipment and helicopters to douse damaged reactor No. 3 for the past five days.
Temperatures at spent-fuel cooling pools at all six reactors measured below 100 degrees Celsius (212 degrees Fahrenheit), Kyodo News said.
“These readings are something that Japanese people can be relieved to hear,” Kyodo quoted Defense Minister Toshimi Kitazawa as saying at a press conference yesterday.
The longer Tepco can prevent overheating of the reactor cores and water-filled pools used to store spent fuel, the smaller the supply becomes of the most dangerous, volatile elements, said Roger N. Blomquist, principal nuclear engineer at the Argonne National Laboratory, near Chicago.
The radioactive nature of the fuel means that it’s in a constant state of decay, he said. Even if some of the nuclear material has started melting, restoring electrical systems will enable Tepco to bring temperatures down to a manageable level so corrective measures and a cleanup can begin, said Blomquist, who oversees the nuclear section at Argonne, an Energy Department research center managed by the University of Chicago, birthplace of the nuclear industry.
Edano, the chief cabinet secretary, said radiation above government limits was found in milk and spinach produced near the plant struck by the earthquake, Japan’s strongest on record. Japan’s Health Ministry asked residents of the town of Iitate in Fukushima prefecture to refrain from drinking tap water because of radioactive iodine, Kyodo News reported.
People living within 30 kilometers of the plant should wear masks and long sleeves and stay out of the rain, Japan’s nuclear safety agency said.
Residents in an adjacent region that covers an area equivalent in size to Los Angeles were evacuated in the first few days after the disaster.