Removal of hydrogen starts at fukushima plant

Tokyo Electric Power Company will try to remove more hydrogen from the troubled Fukushima Daiichi nuclear power plant on Sunday. The density of the gas increased in pipes connected to the No. 1 reactor after a significant drop on Saturday. Last month, TEPCO found that hydrogen had built up inside pipes leading to the No. 1 reactor containment vessel and its density was between 61 and 63 percent of the total gas present. This poses a problem because releasing high densities of hydrogen outside the reactor building could cause another explosion, Japan''s (NHK World) website reported. On Saturday, TEPCO spent one hour removing hydrogen, while at the same time injecting nitrogen to the pipes to reduce the risk of an explosion. About half an hour later, the company found the percentage of hydrogen had dropped to nearly zero. However 2 hours later, the density was measured at 3.9 percent. Even though TEPCO said an explosion is unlikely, hydrogen at a density of over 4 percent could cause a blast when mixed with oxygen. TEPCO believes that the hydrogen level rose because gas accumulated in the upper part of the pipes may have redistributed internally.