Tokyo Electric Power Co. on Thursday began injecting nitrogen into the Fukushima No. 1 atomic plant’s reactor 3 to reduce the risk of further hydrogen explosions, a significant step forward in the effort to contain the nuclear crisis that started March 11.
If successful, Tepco will complete its goal of injecting the inert gas into all three crippled reactors by mid-July, indicating that bringing the crisis under control is basically on track. Tepco has already started operating a new system to circulate water around the three reactors to cool the nuclear fuel inside.
Under a road map outlined by Tepco and the government, stabilizing the crippled reactors by mid-July is the first step toward achieving a cold shutdown by January at the latest.
Nitrogen is being injected into the reactor’s primary containment vessel to keep the ratio of hydrogen at an acceptably low level and prevent an explosion that could possibly release massive amounts of radioactive substances.
Though the nitrogen injection may cause radioactive substances to leak from the containment vessel, the Nuclear and Industrial Safety Agency said the surrounding environment will not be affected. Reactor 3 uses highly dangerous mixed plutonium-uranium oxide (MOX) fuel.
Tepco plans to strengthen radiation monitoring inside the plant.
The company and the government will announce a new road map Tuesday highlighting their work schedule through the second step and beyond.
The new schedule may also indicate whether the government is planning to reduce the scope for evacuation around the crippled Fukushima plant. Chief Cabinet Secretary Yukio Edano said Thursday the government is considering reducing the number of areas subject to possible evacuation in the event the crisis deepens.
In April, about 67,000 residents in a zone 20 to 30 km from the plant, including the towns of Hirono and Naraha, were instructed to prepare to evacuate or remain indoors if the accident worsens.
Edano didn’t mention the prospect of whether locals evacuated from the 20 km no-go zone could return home.
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