injecting nitrogen

The operator of the Fukushima Daiichi nuclear power plant has started injecting nitrogen, an inert gas, into the pressure vessels of the crippled reactors to prevent another hydrogen explosion.In late October, Tokyo Electric Power Company began extracting gases from the containment vessel of the No.2 reactor to remove radioactive substances. During the work, TEPCO found hydrogen accumulating in parts of the reactor at a density of up to 2.9 percent.TEPCO started pumping nitrogen into the pressure vessels of the No.1, 2, 3 reactors on Thursday to lessen the concentration of hydrogen.The density of hydrogen accumulating in the containment and pressure vessels is thought to be below 4 percent, the level where an explosion could occur.TEPCO says the nitrogen injection will push out hydrogen and reduce its concentration.Keeping hydrogen density low is an indispensible condition in the second step of the process decided upon by the government and TEPCO to resolve the nuclear accident. They are aiming to achieve a state of cold shutdown for the reactors by the end of the year.The Nuclear and Industrial Safety Agency plans to assess how well TEPCO can manage hydrogen levels.