The Osaka prefectural government disclosed simulation results March 16 on how its region would be affected by a nuclear disaster at one of four power plants in nearby Fukui Prefecture.
The Osaka prefectural government disclosed simulation results March 16 on how its region would be affected by a nuclear disaster at one of four power plants in nearby Fukui Prefecture.
It said thyroid gland radiation readings were projected to exceed 100 millisieverts, a threshold level for indoor evacuation, in one of 106 cases that were simulated with different accident sources and weather conditions.
It added that readings of between 50-100 millisieverts could be expected in 11 of the 106 simulations.
The results were based on a simulation of a disastrous nuclear accident on a par with the one at the Fukushima No. 1 nuclear power plant last year.
This is the first time Osaka authorities have officially studied the potential impact of a nuclear crisis.
The simulations were done by the Lake Biwa Environmental Research Institute, which is overseen by the Shiga prefectural government.
The institute assumed that a major nuclear emergency had occurred at one of the four existing nuclear power plants in Fukui Prefecture--Tsuruga, Mihama, Oi and Takahama--and that radioactive substances spewed for six hours on a day of gentle and sustained northerly winds.
The diffusion of radioactive iodine was simulated, and thyroid gland radiation readings were evaluated in four stages, ranging between zero and 500 millisieverts.
One simulation, assuming the weather conditions of March 6, 2010, and an accident at the Takahama nuclear plant, indicated doses in excess of 100 millisieverts near the northwestern end of Osaka Prefecture in and around Nose.
Another case study, based on the same weather conditions and a hypothetical accident at the Oi nuclear plant, forecast readings below 100 millisieverts but in excess of 50 millisieverts--the International Atomic Energy Agency's standard for the intake of stable iodine tablets--in a zone in the east of the prefecture between Takatsuki and Tondabayashi.
"My policy is to disclose everything, including unfavorable information," said Osaka Governor Ichiro Matsui, in releasing the simulation results.