information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise
14 Décembre 2012
December 14, 2012
http://mainichi.jp/english/english/newsselect/news/20121214p2a00m0na009000c.html
In yet another embarrassing admission for a nuclear watchdog, the Nuclear Regulation Authority (NRA) announced on Dec. 13 that all of its radiation dispersion forecast maps for Japan's nuclear plants were riddled with errors.
The maps were drawn up to show the predicted spread of radioactive materials in the event of a nuclear disaster at any of the 16 plants, and released to the public in October this year.
The NRA's secretariat gave verbal warnings to Deputy Secretary-General Hideka Morimoto and two other officials -- Yoshihide Kuroki and Shuichi Kaneko -- the same day. The NRA has released revised maps based on recalculated data.
According to the NRA, at least 2,200 mistakes -- including weather data input and processing errors -- were found in the radiation forecast maps. In response, the NRA secretariat is poised to set up a quality control division to prevent a recurrence.
"It was our first failure and we learned a lot from it. It's important not to repeat the mistake," said NRA Chairman Shunichi Tanaka.
The maps were based on calculations of the projected spread of radioactive materials in emergencies including core meltdowns in all reactors at each of the nuclear stations. The maps show the furthest points in 16 directions around the plants where radiation doses could reach 100 millisievert per week -- the International Atomic Energy Agency (IAEA)'s emergency evacuation standard.
After the maps were released, a series of mistakes were found and corrected, prompting the NRA to re-examine the calculation processes for all maps. The revised versions are very different from the previous versions, especially for the Genkai nuclear plant in Saga Prefecture, the Sendai plant in Kagoshima Prefecture, and the Tomari plant in Hokkaido. For other nuclear plants, the regulatory body made such revisions as increasing or decreasing the radioactive material diffusion distances by 0.1 to 4.8 kilometers.
The NRA secretariat and the Japan Nuclear Energy Safety Organization (JNES), which was commissioned to calculate the data and made input mistakes, have said they will jointly check their work thoroughly to prevent a recurrence.
The revised radiation forecast maps can be viewed on the NRA's website at: http://www.nsr.go.jp/committee/kisei/20121213.html
December 13, 2012
http://www.japantimes.co.jp/text/nn20121213x1.html
Kyodo
The Nuclear Regulation Authority said Thursday a thorough review of its mistake-plagued projections for the spread of radiation turned up errors in the data for every atomic power plant in Japan.
The regulatory body examined the data in detail to ensure there would be no more mistakes in the projections. Local governments are expected to use the information to craft plans to prepare for nuclear disasters.
The NRA said there were significant changes in diagrams for how radiation could spread in the event of crises at Kyushu Electric Power Co.'s Genkai and Sendai power plants and Hokkaido Electric Power Co.'s Tomari nuclear complex, compared with the previously revised projections released Oct. 29.
The three projections had to be revised either because the plant operators supplied erroneous weather information or because the data were incorrectly processed by the Japan Nuclear Energy Safety Organization, which was tasked with creating the projections.
The process of calculating the projections for the remaining 14 plants across the country, including disaster-hit Fukushima No. 1 operated by Tokyo Electric Power Co., also contained errors or was mishandled, although this did not result in drastic changes in the projections, according to the NRA's secretariat.
The simulation showed the distances at which doses could reach 100 millisieverts a week after a severe crisis like last year's three meltdowns at Fukushima No. 1. At that dose level, evacuation is recommended by the International Atomic Energy Agency.
The latest projections show the most distant point where such severe radiation could spread is 40.1 km east of Tepco's Kashiwazaki-Kariwa plant in Niigata Prefecture. That point is in the city of Nagaoka.
In the earlier projections, the NRA said the most distant point would still be in Nagaoka, but 40.2 km from Tepco's facility, the largest nuclear plant in the world.
The Nuclear Regulation Authority (NRA) on Dec. 13 released corrections to all of its radiation forecast maps, which show the likely spread of radioactive substances from a serious accident at 16 nuclear power plants across Japan.
The corrections affect all of the nuclear plants under study, which do not include the Fukushima No. 1 nuclear plant, site of the reactor meltdowns following an earthquake and tsunami in March 2011, or the Monju prototype fast-breeder reactor.
The forecast maps show the likely spread of radioactive substances in the event of an accident similar in scale to the Fukushima disaster, and the corrections are expected to affect the ongoing efforts by local governments situated near nuclear plants to draw up emergency evacuation plans.
Errors in the maps have been found on successive occasions since the nuclear regulatory agency initially released them on Oct. 24.
The most significant errors discovered in the recent overhaul concerned the forecast maps for the Tomari plant in Hokkaido, the Genkai plant in Saga Prefecture, and the Sendai plant in Kagoshima Prefecture.
The previous map for the Tomari plant was found to have overestimated the area of likely spread because of errors in weather data input. The maps for the Genkai and Sendai plants had to be turned 180 degrees because Kyushu Electric Power Co., operator of the plants, had mixed up the windward and leeward directions.
Local governments have been urged to draw up evacuation plans for areas where the weekly radiation doses are likely to reach 100 millisieverts, and the Dec. 13 corrections affect five municipalities in that regard.
Kutchan and Iwanai, both in Hokkaido, and Akune, Kagoshima Prefecture, were removed from the list of municipalities with areas of 100-millisievert weekly doses, while Tokamachi, Niigata Prefecture, and Sasebo, Nagasaki Prefecture, were added to the list.
Tokamachi, which was initially on the list but was delisted with the Oct. 29 correction, was put on the list again.
The Oct. 29 corrections included 22.5-degree rotations of the forecast maps for six nuclear plants, either clockwise or counterclockwise. The mix-up of windward and leeward directions for the Genkai and Sendai plants was made public by the NRA on Nov. 6. The NRA said it would release corrected maps for the two plants on Nov. 8, but they were not released on that day because more errors were discovered. The NRA instead decided to conduct the latest overhaul on all forecast maps for the 16 nuclear plants.
The NRA said its predecessor, the Nuclear and Industrial Safety Agency (NISA), gave ambiguous instructions when it commissioned the Japan Nuclear Energy Safety Organization (JNES) in March to create the forecast maps. JNES, which won the contract, failed to double-check the specifications, while the NRA also failed to define the procedures for checking them after it took over the mission from the now-defunct NISA.
The NRA on Dec. 13 verbally admonished three officials in charge of the matter.
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