December 16, 2011
9:54 am EDT
Reuters reported this morning that the Japanese prime minister declared that the Fukushima Daiichi nuclear energy facility is in a state of cold shutdown. See story:
TOKYO, Dec 16 (Reuters) – Japan declared its tsunami-stricken Fukushima nuclear power plant to be in cold shutdown on Friday, taking a major step to resolving the world’s worst nuclear crisis in 25 years but some critics questioned whether the plant was really under control.
The Fukushima Daiichi plant, 240 km (150 miles) northeast of Tokyo, was wrecked on March 11 by a huge earthquake and a towering tsunami which knocked out its cooling systems, triggering meltdowns, radiation leaks and mass evacuations.
In making the much-anticipated announcement, Prime Minister Yoshihiko Noda tried to draw a line under the most acute phase of the crisis and highlighted the next challenges: the clean-up and the safe dismantling of the plant, something the government says may take more than 30 years.
“The reactors have reached a state of cold shutdown,” Noda told a government nuclear emergency response meeting.
“A stable condition has been achieved,” he added, noting radiation levels at the boundary of the plant could now be kept at low levels, even in the event of “unforeseeable incidents.”
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See NEI’s post that explains the difference between “cold shutdown condition,” which is what happened at Fukushima, and the normal process of “cold shutdown.”
December 12, 2011
1:49 pm EDT
TEPCO Workers Lay Cables to Restore Power to Fukushima Daini
Struggling against earthquake aftershocks, devastating floodwaters and debris, employees at Tokyo Electric Power Co.’s (TEPCO) Fukushima Daini nuclear energy facility safely shut down all four of the facility’s reactors within days of the historic 9.0-magnitude earthquake and tsunami that struck on March 11. The facility is located only seven miles southwest of its sister plant, Fukushima Daiichi, and produces enough electricity to power roughly three million homes and businesses in Japan.
When the earthquake struck, the Fukushima Daini facility automatically shut down safely as designed. However, it went into a state of emergency following the tsunami when water damage disrupted heat removal systems in three of the four reactors.
TEPCO reactor operators were able to quickly bring reactor 3, which had retained its heat removal function, into stable condition in a matter of hours. Meanwhile, other employees worked feverishly around-the-clock to reestablish heat removal capability in the other three reactors and finished stabilizing them by March 15.
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December 2, 2011
4:01 pm EDT
- The industry on Dec. 1 urged the U.S. Nuclear Regulatory Commission staff to consider an integrated and flexible approach toward meeting the NRC’s Fukushima task force recommendations, arguing that this approach would result in faster, more efficient implementation of the most safety-significant recommendations. The industry advocated enhancing the post-9/11 concept of using portable equipment to address loss of all AC power and loss of ultimate heat sink from a variety of natural phenomena. This enhanced mitigation action—called a “diverse and flexible mitigation capability”—could be supplemented by regional response centers that could provide additional hardware and equipment to further extend coping capability should there be a longer-term loss of power or cooling capability.
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November 21, 2011
4:31 pm EDT
- The Japanese cabinet has approved “basic policies” to clean up radioactive contamination resulting from the Fukushima Daiichi accident. Based on recommendations made in 2007 by the International Commission on Radiological Protection, areas contaminated to dose levels within two rem per year above background will be cleaned up to reduce adult doses by 50 percent within two years and 60 percent for children, and to a long-term level of 0.1 rem/year above background radiation levels. Two rem is about the same amount of radiation exposure a patient would receive from a full body CT scan. Areas where the annual dose levels are above two rem/year will be given priority in scheduling decontamination activities.
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November 16, 2011
5:16 pm EDT
- Shikoku Electric Power Co. has submitted the results of first-phase stress tests for its Ikata Unit 3 reactor to the Nuclear and Industrial Safety Agency. The results show Ikata 3 could withstand an earthquake with ground acceleration 1.9 times as strong as the reactor’s design basis and a 47-foot tsunami, four times its design basis. Shikoku Electric is the second utility to submit a stress test result after Kansai Electric did so for its Ohi Unit 3 reactor Oct. 28. Read More »