Editor's Note: John Boyd is an IEEE Spectrum contributor reporting from Kawasaki, Japan. This is part of IEEE Spectrum's ongoing coverage of Japan's earthquake and nuclear emergency. For more details on how Fukushima Dai-1's nuclear reactors work and what has gone wrong so far, see our explainer and our timeline.
An independent panel of experts met for the first time Tuesday to look into the Fukushima Dai-1 nuclear plant accident from a variety of perspectives. The panel, headed by Yotaro Hatamura, professor emeritus at the University of Tokyo, has been given the authority to question all entities involved, including TEPCO, government ministers, and even the prime minister.
The ten-person panel is made up of several academic along with a lawyer and the mayor of one of the towns in Fukushima. They are all from outside the nuclear industry to ensure impartiality. In addition, two technology advisors have been assigned to help the members with technical questions.
Dubbed the “investigation and verification committee”, the panel will examine the technology and social aspects that led to the accident, but will not seek to assign blame. In addressing the panel, Prime Minister Naoto Kan said, “A closed inner-circle of pro-nuclear scientists and bureaucrats has made energy policies (to date). I would ask you to discuss if such a policy-making process should be maintained, and to examine the accident from various standpoints, not just the technical aspect.”
As if to underscore the prime minister’s veiled criticism of the policy-making process, NHK, Japan’s national broadcaster, said it had obtained a draft of an official report that says the government intends to make the Nuclear and Industrial Safety Agency (NISA), the country’s nuclear regulator, an independent body. At present, the agency comes under the wing of the Ministry of Economy, Trade, and Industry (METI), which is regarded as being a proponent of nuclear power. The aim of the restructuring is to better assign roles and responsibilities should another disaster hit the nuclear industry.
According to NHK, the leaked report also calls on Tokyo Electric Power Co. (TEPCO) to improve the design of its nuclear plants so that cooling systems continue to function in the wake of a major disaster—an obvious recommendation given the systems for reactors Nos. 1, 2 and 3 in the Fukushima nuclear plant all failed after the tsunami struck on 11 March, as did all their emergency power back-up systems. The report also points out that the present location of the storage pools used to store spent fuel rods are too high to be readily accessed and so are hampering workers’ efforts to bring the situation under control.
The leaked decision to separate NISA from METI mirrors preliminary suggestions made by an inspection team of nuclear experts from the International Atomic Energy Agency (IAEA) who visited Japan from 27 May 27 to 2 June and recommended that NISA should be made independent and its role clarified. The report will be reviewed by the government’s nuclear taskforce before it is submitted to the IAEA’s Ministerial Conference on Nuclear Safety to be held from 20 June in Vienna.
IAEA’s Director General Yukiya Amano said on Monday that the upcoming, “Ministerial Conference is of vital importance for global nuclear safety after the Fukushima Dai-1 accident. Its main goals are to make a preliminary assessment of the accident, strengthen emergency preparedness and response, and launch the process of reviewing the global nuclear safety framework in order to strengthen it.”
Meanwhile work continues to bring the stricken plant under control. On Saturday TEPCO reported detecting radiation readings as high as 4000 millisieverts per hour inside the No. 1 Reactor building. The readings were taken by a robot sent into the building on Friday. Radiation was measured near the floor under which is located the reactor’s torus. The torus is a safety structure into which steam can be vented if the pressure in the pressure vessel rises to high. TEPCO believes highly radioactive water from the reactor has collected in the torus and is probably the source of the radiation
According to Kyodo News, the government nuclear task force is considering limiting the radiation dose for workers clearing the contaminated debris caused by the hydrogen explosions in the plant to 20 millisieverts per year. But sources cited in the Kyodo report noted that “the limited number of dosimeters could make policing the rule difficult.”
TEPCO reported on Friday that two employees working in the plant site have exceeded the exposure limit of 250 millisieverts of radiation. Citing data from the National Institute of Radiological Science, TEPCO said the two men had absorbed high levels of radioactive iodine-131 with internal exposure levels ranging between 200 to 580 millisieverts. NHK reported that the two men were working without masks in the control rooms of reactors No. 3 and 4 at the time of the hydrogen explosion in the No. 1 Reactor building, the day after the earthquake struck.
In response to this disclosure, the Ministry of Health, Labor and Welfare sent for inspectors to the plant on Tuesday to check working conditions and to question TEPCO site managers.
The two men have now been transferred to work at the Fukushima Dai-2 plant to avoid further exposure. The government had originally set a limit of 50 millisieverts of radiation exposure per year, but increased it to 100 millisieverts soon after the accident, then increased it again to the present 250 millisieverts in order to be able to deal with the emergency.