The New York Times reports the threat of nuclear meltdown is still very real at Japanese reactors impacted by Friday’s tsunami. At Fukushima Daiichi Nuclear Power Station’s Reactor 2, at least parts of the fuel rods have been exposed for several hours, suggesting some of the fuel has begun to melt. The Times quotes an anonymous nuclear industry executive saying Japanese power industry managers were “basically in a full-scale panic” late Monday night after several attempts to cool the reactor failed:
“With the cooling systems malfunctioning simultaneously at three separate reactors at the Fukushima Daiichi Nuclear Power Station after the powerful earthquake and tsunami, the acute crisis developed late Monday at reactor No. 2 of the plant, where a series of problems thwarted efforts to keep the core of the reactor covered with water — a step considered crucial to preventing the reactor’s containment vessel from exploding and preventing the fuel inside it from melting down.
The plant’s operator, Tokyo Electric Power, said late Monday that repeated efforts to inject seawater into the reactor had failed, causing water levels inside the reactor’s containment vessel to fall and exposing its fuel rods. After what at first appeared to be a successful bid to refill the vessel, water levels again dwindled, this time to critical levels, exposing the rods almost completely, company executives said.
Workers were having difficulty injecting seawater into the reactor because its vents — necessary to release pressure in the containment vessel by allowing radioactive steam to escape — had stopped working properly, they said.
The more time that passes with fuel rods uncovered by water and the pressure inside the containment vessel unvented, the greater the risk that the containment vessel will crack or explode, creating a potentially catastrophic release of radioactive material into the atmosphere — an accident that would be by far the worst to confront the nuclear power industry since the explosion of the Chernobyl nuclear power plant 25 years ago.”