"We are considering injecting nitrogen into the container of reactor number 1 because hydrogen gas has possibly accumulated in the container," a Tokyo Electric Power Co. (TEPCO) official said. The plan is to inject nitrogen, an inert gas abundant in the atmosphere, to displace the oxygen that could react dangerously with the hydrogen. NTV reported that the nitrogen injection operation could take place "as early as today".
In the days after the March 11 earthquake and tsunami crippled the plant, an accumulation of hydrogen near the reactors caused large explosions that heavily damaged the outer buildings housing them. The latest worries signal the fragility of the situation at the Fukushima Daiichi plant more than three weeks after the disasters that knocked out reactor cooling systems, triggering explosions and fires and releasing radiation. The plant northeast of Tokyo has emitted radioactive materials into the air, contaminating farm produce and drinking water. The concerns over hydrogen came after TEPCO reported some progress earlier in the day, announcing that leakage of highly radioactive water from a cracked concrete pit at reactor number 2 has stopped.