Japan Fears Reactor Core Breach Damage may have occurred in explosion last week By Mary Papenfuss, Newser User Posted Mar 25, 2011 2:24 AM CDT Updated Mar 25, 2011 7:51 AM CDT 6 comments Comments White smoke billows from the No. 3 unit of the Fukushima Dai-ichi nuclear power plant last week. (AP Photo/Tokyo Electric Power Co.) (Newser) – Japanese officials fear that one of the reactor cores of the Fukushima nuclear facility may have been breached, raising the specter of significant environmental damage and halting work at the nuclear complex. "It is possible that somewhere the reactor may have been damaged," says a spokesman for the nation's nuclear safety agency. Officials are hopeful the damage is limited because the crippled Unit 3 reactor still appears to retain some of its "containment functions," he adds. The plant has leaked some low levels of radiation, but a breach could mean a much larger release of contaminants. Suspicions of a possible breach were raised when two workers waded into water 10,000 times more radioactive than is typical and suffered skin burns, the agency says. Officials believe the damage may have occurred last week when a hydrogen explosion destroyed Unit 3's outer containment building. It's possible the core has not been breached and that the damage was limited to surrounding areas, such as in piping or the containment pool, reports AP. The crippled reactor holds some 170 tons of radioactive fuel at its core.