Japan's government and the owner of the damaged Fukushima Daiichi nuclear power plant are reviewing efforts to wind down the two-month crisis as thousands of nearby residents await word regarding planned evacuations.Plant workers are making step-by-step progress toward restoring normal cooling, the Tokyo Electric Power Co. said.
But a new radiation leak was found Wednesday outside Reactor 3 at the plant, TEPCO said later. Surface radiation was detected as high as 1.5 msv per hour, TEPCO said, but the company added that it cannot confirm if the radioactive water is leaking into the sea.
Nearly 80,000 people have spent two months away from their homes in the 20-kilometer (12.5-mile) zone around the plant, while tens of thousands more are awaiting orders to evacuate more distant towns where radiation levels are likely to raise the long-term cancer risk.
In the city of Fukushima, displaced residents berated Tokyo Electric President Masataka Shimizu and other top utility executives, who asked for forgiveness on their hands and knees Tuesday. About 100 residents from the village of Kawauchi were allowed to return home for a short visit.
They were issued protective gear, allowed to pack one small bag and spend two hours in their homes. Some returned to find pets -- left behind in the initial confusion -- dead of starvation, Japan's Environment Ministry reported Wednesday.
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Private animal-rescue groups had mounted expeditions into the evacuation zone to rescue pets before the government began enforcing the restricted area in late April. Government officials plan to retrieve other pets Wednesday, the ministry said.
Residents of several cities and towns outside the 20-kilometer zone have been told to be ready to move by mid-May. They were put on notice in April that evacuation orders would be coming in about a month, and about a third have already left, government spokesman Noriyuki Shikata said Wednesday.
"It depends on the circumstances of individuals," Shikata said. "It's a bit difficult to get the most updated figure, but I understand that over half the original residents are still residing in the zone."
Tokyo Electric and Japanese nuclear regulators have been trying to wind down the crisis at Fukushima Daiichi since March 11, when the massive earthquake and tsunami that struck northern Japan's Tohoku region knocked out the plant's cooling systems. The result was the world's worst nuclear accident since Chernobyl, compounding a natural disaster of historic proportions.
Japan marked two months since the earthquake and tsunami with a moment of silence Wednesday. While no deaths have been attributed to the Fukushima Daiichi accident, the earthquake and tsunami have killed nearly 15,000 and left 10,000 more missing, Japan's National Police Agency reported.
In early April, Tokyo Electric announced a six- to nine-month plan to bring the nuclear crisis to an end by restoring normal cooling systems and fully shutting down the reactors. That plan is being reviewed by the utility and the government, and its results are expected to be announced in mid-May, Tokyo Electric spokesman Hiro Hasegawa said Wednesday.
Tokyo Electric has "a number of balls in the air" as it tries to wind down the crisis, said Margaret Harding, a nuclear engineer and former executive at General Electric, which designed the reactor.
"We want them going in with a well thought-out plan that will succeed, because failure here is really not something any of us want them to have happen," Harding said.
The three operating reactors at Fukushima Daiichi overheated, massive hydrogen explosions blew apart the buildings housing units 1 and 3 and another suspected hydrogen blast is believed to have damaged the No. 2 reactor. Engineers have been pouring hundreds of tons of water a day into the reactors since as an emergency measure, and have also struggled to keep spent fuel pools in units 1, 3 and 4 from overheating.
Huge quantities of radioactive materials spewed from the plant, prompting Japan to declare the accident a top-scale event on the international rating system for nuclear disasters. Thousands of tons of radioactive water have flooded the basements where the cooling systems were housed, making it impossible for workers get into the facilities.
Workers have been able to install air filters inside the No. 1 reactor building to limit the further release of radioactive particles and have begun filling the primary containment shell around the reactor core with water to cover the now-exposed fuel rods, said Yoshikazu Nagai, another spokesman for Tokyo Electric.
The plan will be to recirculate that water through a heat exchanger to cool it, then send it back into the reactor, Nagai said -- essentially building a new cooling system. Similar plans are being considered for unit 2, which is believed to be leaking radioactive water, and 3, where engineers noted a disturbing rise in the reactor's temperature readings last week.
"First we have to tackle unit No. 1, and we need to see if we can succeed," Nagai told CNN.
Equipment that will be used to decontaminate the stagnant, radioactive water pooling in the plant's basements is expected to arrive by mid-May, he said.
The spent but still-energetic fuel assemblies housed in pools of water at the reactor sites remain a concern, however. Water samples taken Sunday from the No. 3 spent fuel pool showed a sharp spike in levels of radioactivity after finding negligible concentrations of reactor byproducts such as radioactive iodine and cesium the previous week, the company reported.
A previous increase in radiation levels in the unit 4 spent fuel pool was blamed on radioactive debris falling into that pool, which was exposed by damage to the reactor building. But the cause of Sunday's reading was unknown, Nagai said.
Meanwhile, Japanese Prime Minister Naoto Kan says his government will rethink its plans for nuclear energy "from scratch" as a result of the disaster.
"Under the basic plan for energy in 2030, the proportion of nuclear energy and total electricity supply would be 50% for nuclear energy and 20% renewable energy," Kan told reporters Tuesday. "But with the occurrence of a major nuclear disaster, the basic plan for energy is going to have to be reviewed thoroughly, from scratch."
Alternative sources of energy like biomass, wind and solar "should be regarded as one of the major pillars" in a new plan, Kan said, and conservation efforts will be ramped up.
In addition, after years of complaints from anti-nuclear activists, his government called on Japanese utility Chubu Electric to shut down the Hamaoka nuclear power plant southwest of Tokyo. The facility sits on a fault line that Japan's science ministry says has an 87% chance of producing a massive earthquake within the next three decades.
Chubu Electric said it would suspend operations at Hamaoka "until further measures" are completed to protect the plant from a tsunami like the one that crippled Fukushima Daiichi.
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