The operators of Japan's Fukushima nuclear plant say they are moving equipment to higher ground after a series of strong aftershocks that have hampered efforts to repair the crippled facility.
The latest strong tremor came at about 6 a.m. local time Thursday, with a magnitude of 6.1. It was the fourth aftershock since Monday with a magnitude of 6 or greater and the 14th with a magnitude greater than 5. Hundreds of aftershocks have rattled Japan's northeastern coast since the massive 9.0 earthquake and tsunami on March 11 that knocked out the plant's cooling systems.
Officials with the Tokyo Electric Power Company said Thursday they are reinforcing connections to the national electrical grid to make sure they have power to pump water into the plant's reactors and cooling ponds. A spokesman said generators and other equipment are being moved to higher ground to protect against another tsunami.
Workers at the plant are also seeking a way to remove spent fuel rods from a storage pond at the plant's number four reactor, where elevated radiation levels have been detected in the water. Officials said Wednesday that the radiation levels suggest that some of the rods have been damaged, though most are likely intact.
Technicians managed to pump more than 250 tons of highly radioactive water out of a tunnel next to another of the plant's reactors on Wednesday, an essential step before they can resume work on repairing the unit's vital cooling systems. But Japan's NHK Television said the water level in the tunnel had risen again Thursday morning, suggesting water is still leaking into the tunnel from the reactor.
NHK quoted plant officials as saying radiation levels in the ocean near the plant have dropped dramatically since a leak was plugged last week but are still high. The latest reading found radioactive iodine at 2,500 the legal limit, compared to 7.5 million times the limit on April 2.
The network also reported that recent health ministry testing has found radiation at 25 times the legal limit in fish caught south of the nuclear plant on Wednesday, and that radioactivity was detected on 11 kinds of vegetables sampled in Fukushima prefecture on Monday.
The toll from the March 11 disaster continues to rise, with Japan's national police agency reporting more than 13,300 confirmed dead and more than 15,000 missing.
Japan's Kyodo news agency says many of the victims died when officially designated evacuation sites were swamped or washed away by the tsunami, which was as high as a three-story building when it hit the coast. The agency says it has identified more than 100 evacuation sites that failed to stand up to the tidal wave.
Some information for this report was provided by AP.