It will take up to nine months before the crippled Fukushima Daiichi Nuclear Power Station in Japan is stabilized, facility owner Tokyo Electric Power Co. (TEPCO) said last week. Radiation has been leaking from the complex since a massive earthquake-triggered tsunami inundated Japan’s Pacific coast and knocked out cooling systems at the plant’s six reactors just over a month ago.

At an April 17 news conference, TEPCO officials unveiled a phased “road map” to bring the crisis under control. In the first three months of the plan, the company hopes to cool the reactors and gradually reduce the level of leaking radiation.

Three to six months after that, the utility expects all of the reactors to achieve “cold shutdowns,” a stable condition in which temperatures drop and radiation leaks substantially decline.

“It is a sign of the extraordinary seriousness of the Fukushima nuclear disaster that TEPCO anticipates it may take nine more months before cold shutdown can be achieved,” Daniel O. Hirsch, lecturer on nuclear policy at the University of California, Santa Cruz, tells C&EN. “Radioactive releases could continue for a long time.”

TEPCO said the plan involves installing a concrete cover over the three badly damaged reactor buildings to contain the radiation. Hydrogen explosions in the buildings in days immediately after the quake blew off their roofs and scattered radioactive debris. The company has been pumping nitrogen gas into plant reactors to help prevent additional hydrogen blasts.

“We will do our utmost to curb the release of radioactive materials by achieving a stable cooling state at the reactors and spent-fuel pools,” TEPCO Chairman Tsunehisa Katsumata told reporters at the briefing. “The company has been doing its utmost to prevent a worsening of the situation. We have put together a road map and will put all our efforts into achieving these goals.”

Robots that are being used to measure the levels of radiation in the nuclear complex have reported radioactivity readings of up to 57 millisieverts per hour. Workers cannot enter these areas because the upper limit for nuclear workers in Japan is 250 millisieverts per year.

Meanwhile, very low levels of radioactive material linked to the damaged nuclear plant in Japan have reached the U.S. West Coast. But analyses of air and water samples for radiation contamination show that the U.S. remains safe, EPA Administrator Lisa P. Jackson told the Senate Environment & Public Works Committee earlier this month (C&EN Online Latest News, April 14).

“Let me be clear. EPA has not seen and does not expect to see radiation in our air or water reaching harmful levels in the U.S.,” Jackson said. “All of the data that we have seen, which we continue to make public and available on our website, indicates that while radiation levels are slightly elevated in some places, they are significantly below problematic levels.”

EPA has 164 monitoring stations spread throughout the 50 states, and the agency measures radioactive substances in air, precipitation, drinking water, and milk.

Recent air samples have contained very small amounts of iodine, cesium, and tellurium, which are consistent with possible releases from the damaged Japanese reactors, Jackson testified. The largest amounts were found in samples from Alaska, she said, but all of the radiation levels detected “are hundreds of times below levels of concern.”

（news from：Chemical & Engineering News）