Continued from page 1

The radiation was far higher than that measured in the spent fuel pool of Unit 4, suggesting the damage to the fuel in Unit 2 is greater.

As work continues inside the plant to reduce radiation levels and stem leaks into the sea, the Defense Ministry said it would send about 2,500 soldiers to join the hundreds of police, outfitted with protective suits, who are searching for bodies in tsunami debris around the plant.

About 1,000 bodies are thought to be buried in the muddy piles of broken houses, cars and fishing boats. As of Sunday, searchers had located 66 bodies and recovered 63, police said.

The combined earthquake and tsunami have left more than 27,000 people dead or missing.

The robots being used inside the plant are made by Bedford, Mass., company iRobot. Traveling on miniature tanklike treads, the devices opened closed doors and explored the insides of the reactor buildings, coming back with radioactivity readings of up to 49 millisieverts per hour inside Unit 1 and up to 57 millisieverts per hour inside Unit 3.

The legal limit for nuclear workers was more than doubled since the crisis began to 250 millisieverts. The U.S. Environmental Protection Agency recommends an evacuation after an incident releases 10 millisieverts of radiation, and workers in the U.S. nuclear industry are allowed an upper limit of 50 millisieverts per year. Doctors say radiation sickness sets in at 1,000 millisieverts and includes nausea and vomiting.

The robots, along with remote-controlled miniature helicopters, have enabled Tepco to photograph and take measurements of conditions in and around the plant while minimizing the workers’ exposure to radiation and other hazards.

Tepco’s plan for ending the crisis, drawn up at the government’s order, is meant to be a first step toward letting some of the tens of thousands of residents evacuated from the area around the company’s Fukushima Dai-ichi nuclear power plant return to their homes.