Japan's new nuclear industry watchdog is under a cloud again, after admitting to additional errors in its maps caused by faulty weather data on the expected spread of radioactive substances from a nuclear accident.
The Nuclear Regulation Authority admitted on Nov. 8 to more errors in its maps discovered when it was checking data of the Genkai nuclear plant in Saga Prefecture and the Sendai nuclear plant in Kagoshima Prefecture, which are both operated by Kyushu Electric Power Co. It had previously admitted to errors on the two plants on Oct. 29 and Nov. 6 after its initial release on Oct. 24.
Before finding the latest errors, the NRA planned to release corrected forecast maps on Nov. 8. But these mistakes led the NRA to postpone their release to next week or later. The NRA will again check for any additional errors on all the maps, which show the spread of radiation in both direction and distance from all the nation's 16 nuclear power plants in the event of a nuclear accident. Local governments are using the maps to draw up contingency and evacuation plans.
When the NRA first released the maps on Oct. 24, it was forced that evening to correct data on the farthest local governments from the nuclear power plants where weekly radiation doses are likely to reach 100 millisieverts.
On Oct. 29, the NRA was forced to apologize for errors on the distances and directions of the potential spread of radioactive substances from six nuclear plants, including the Genkai plant and the Sendai plant. The Japan Nuclear Energy Safety Organization (JNES) provided the data for the NRA through computer simulations.
On Nov. 6, the NRA announced there were more mistakes on forecasts of the Genkai plant and Sendai plant, and apologized and made corrections on the maps at a news conference. It blamed the errors on incorrect weather data it had been given by Kyushu Electric.
On Nov. 7, the JNES, when making a check for correcting the maps, noticed that it had input incorrect weather data.
Informed by the organization, the NRA decided to delay the release of the corrected maps, although it believes the seriousness of the latest weather data errors by the JNES is minimal.
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