(This post is by Christine McCann)
Here’s the latest of our news bulletins from the ongoing crisis at Japan’s Fukushima Daiichi nuclear power plant.
State of Nuclear Politics in Japan
The Noda Cabinet has adopted an Environment Ministry plan to decontaminate areas affected by the Fukushima Daiichi disaster. Environment Minister Goshi Hosono—who is also the nation’s Nuclear Crisis Minister—said that the government will take responsibility for decontaminating areas where radiation measures one millisievert or more per year in the no-entry and evacuation zones. In other areas, local municipalities will be responsible for decontamination work, although the central government will absorb the cost. By August 2013, the government hopes to reduce radiation by 50% in areas where radiation is less than 20 millisieverts per year, and by 60% in areas frequented by children.
Forty-two Tokyo Electric Power (TEPCO) shareholders have instructed auditors of the utility to file a lawsuit on their behalf, alleging that 61 current and former TEPCO executives failed to protect the Fukushima Daiichi plant from the effects of the March earthquake and tsunami. The shareholders plan to sue for a record-breaking 5.5 trillion yen ($71 billion), and say that they will file the suit themselves if auditors fail to do so. TEPCO had no comment.
For the first time since the March nuclear disaster, a select group of journalists was allowed to tour J-Village, the former sports complex being used by as many as 3,300 TEPCO employees involved in cleanup efforts at the Fukushima nuclear plant. The compound’s 12 soccer fields now house sleeping facilities for 1,000 workers, helipads, decontamination areas, and a medical center, as well as a cafeteria and laundry. The complex also stores nuclear waste in the form of used protective clothing and safety gear. Currently, almost half a million sets of radioactive gear is being stored there. Workers are checked daily for radiation exposure and receive a whole body counter (WBC) exam monthly. The facility provides a sharp contrast to workers’ living conditions in the months immediately following the accident, when workers slept on floors and were given only a biscuit for breakfast and a bowl of noodles for dinner. One worker said, “Conditions have gotten better but it’s still tough.”
During the tour, the Director of the Fukushima Daiichi plant, Masao Yoshida, took questions from reporters and admitted that in the first week after the nuclear disaster, he thought he might not survive. Yoshida apologized to residents of Fukushima Prefecture and the Japanese people, and admitted, “Though they [the reactors] are stable, they are not safe.”
State of the Reactors
TEPCO is continuing its efforts to move the Fukushima Daiichi plant toward “cold shutdown status.” The government has defined cold shutdown as reducing temperatures with the reactors to below 100ºC, reducing and managing radiation leaking from the plant, and maintaining stable cooling systems. This week, Nuclear Crisis Minister Goshi Hosono said that TEPCO must also ensure that temperatures of melted fuel, which has leaked through the reactor pressure vessels, remain below 100ºC. That order poses a challenge for the utility; equipment designed to monitor the reactors was damaged in the tsunami, and radiation levels are so high that workers have been unable to repair it. Experts point to last week’s incident in which TEPCO said that criticality may have occurred in reactor #2—a statement they later rescinded, saying that instead, spontaneous fission was occurring—as an example of TEPCO’s inability to accurately assess the ongoing state of the reactors.
Contamination (Includes Human Exposure)
Japan’s Science Ministry has released a new radiation map revealing the spread of cesium over 18 prefectures, six more than previous maps which only showed radiation readings for 12 prefectures. Ministry officials say that cesium spread to the western border between Gunma and Nagano prefectures, and to Iwate Prefecture in the north. Cesium levels in Iwate and Nagano Prefectures exceeded 30,000 Bq/m2; in four other towns, levels exceeded 60,000 Bq/m2. Officials believe that the mountains near Gunma and Nagano may have prevented radiation from traveling further west.
A study by researchers at the University of Tsukuba and Nihon University asserts that high levels of contamination measured in cities and towns over 160 km from the Fukushima Daiichi plant can be attributed to rain that fell between March 21 and 23, washing radiation down on areas of Togichi, Saitama, and Chiba prefectures, as well as Tokyo.
Medical professionals in Fukushima are now traveling to administer thyroid ultrasound exams to children, after parents complained that the prefecture’s single examination site was too far for many to access. When children are exposed to radioactive iodine, such as that released in the Fukushima nuclear disaster, they are at increased risk for thyroid cancer. Doctors expect to conduct ultrasounds every two years until the children reach the age of 20, and then every five years after that.
Radioactive cesium levels measuring 649 Bq/kg have been discovered in kuritake mushrooms grown outdoors in Tochigi Prefecture, 120 km southwest of the site of the Fukushima nuclear disaster. The government limit is 500 Bq/kg. Earlier this month, contaminated shiitake mushrooms were found 260 km from the plant, in Yokohama. The mushrooms are being recalled, and farmers have been asked to voluntarily refrain from shipping more.
Decontamination Efforts and Waste Disposal
Scientists from Hiroshima International University have mixed photosynthetic bacteria with radioactive sludge using a process that removes 90% of the cesium. The positive charge of cesium is attracted to the negatively charged bacteria; researchers believe that bacteria then absorb the cesium. Ken Sasaki, one of the scientists involved with the study, said that the method is inexpensive and the resulting waste is 75 times lower in volume than the original radioactive materials. The team hopes it can be used on soil in areas affected by the nuclear disaster.
Other Nuclear News
The International Atomic Energy Agency (IAEA) released a statement saying that low levels of radioactive iodine-131 have been discovered in the Czech Republic, Germany, Poland, Slovakia, Sweden, Hungary, Denmark, and Austria. IAEA officials insist that the levels do not pose a risk to human health, but admit they have been unable to pinpoint the source of the radiation. Experts do not believe it is coming from the Fukushima plant. One official said, “We are a little concerned, because there must be a source somewhere.” The IAEA is continuing to investigate.