Tokyo Electric Power Co. began efforts Wednesday to stem the possibility of a hydrogen explosion at the quake-damaged Fukushima Daiichi nuclear power complex. The utility, known as Tepco, was preparing Wednesday night to deal with the potential that hydrogen gas in the plant’s No. 1 reactor could come into contact with oxygen and explode—a scenario that could damage the reactor’s containment vessel and leak large quantities of radioactive material. The containment vessel is meant to be airtight. But the overheating of fuel rods following the breakdown of the cooling system in the wake of last month’s earthquake, and the subsequent pumping of seawater into the reactor, are believed to have damaged some of the vents and pipes running in and out of the reactor. Overheating of the reactor is also likely to have damaged the control rods, which help control the speed of a nuclear reaction. As a result, Tepco has said it has been mixing boron into the cooling water for the past three weeks. Boron absorbs neutrons and helps prevent so-called recriticality, in which the nuclear reaction accelerates and reaches a self-sustaining level that is difficult to stop.
Japan Must Repair Cooling Function to Stop Nuclear Plant Leaks
