Japan reactor core may be leaking radioactive material, official says

Japan nuclear core may be leaking

STORY HIGHLIGHTS

• NEW: Japan nuclear agency: Screeners have examined 87,813 people for exposure
• NEW: Work stops at two other reactors with high radiation levels in water, utility says
• Discovery of contaminated water suggests nuclear core leak, Japan officials say
• Three workers who stepped in the water were exposed to radiation

Tokyo (CNN) -- Authorities in Japan raised the prospect Friday of a likely breach in the all-important containment vessel of the No. 3 reactor at the stricken Fukushima Daiichi nuclear power plant, a potentially ominous development in the race to prevent a large-scale release of radiation.

Contaminated water likely seeped through the containment vessel protecting the reactor's core, said Hidehiko Nishiyama of the Japan Nuclear and Industrial Safety Agency.

Three employees working near the No. 3 reactor Thursday stepped into water that had 10,000 times the amount of radiation typical for a nuclear plant, Nishiyama said. An analysis of the contamination suggests "some sort of leakage" from the reactor core, signaling a possible break of the containment vessel that houses the core, he said.

The workers have been hospitalized and work inside the reactor building has been halted, according to the agency.

Work inside two other reactor buildings also had to stop and workers had to be pulled back Friday after the discovery of high levels of radiation in water at those locations, a Tokyo Electric Power Company official said Saturday. Water is still being pumped into the containment vessels, the utility official said.

Nuclear power experts cautioned against reading too much into the newest development, saying the workers exposed to radioactive water might not suffer injuries any more serious than a sunburn.

Moreover, evidence of radioactivity in the water around the plant is not necessarily surprising given the amount of water sprayed onto and pumped into the reactors, said Ian Hutchinson, professor of nuclear science and engineering at the Massachusetts institute of Technology.