The radioactive dust emitted from the Fukushima Dai-ichi Power Plant is not expected to hit Taiwan in the coming three days, and even if it did, over the first few days of a worst-case scenario, residents would receive a smaller radiation dose than from a computerized tomography (CT) scan, Atomic Energy Council (AEC) officials said yesterday.
AEC Minister Tsai Chuen-horng (蔡春鴻) made the remarks amid a spiraling crisis at the complex, where three active reactors and their cooling systems were seriously impaired by the massive earthquake and ensuing tsunami on Friday.
“Based on an analysis of the wind direction by the Central Weather Bureau, [the dust] will not be blown to Taiwan until at least the 19th of this month,” Tsai said when fielding questions from lawmakers who were concerned whether the nation would be affected by the radioactive dust at the legislature’s Education and Culture Committee.
According to the bureau, Taiwan will mostly be affected by seasonal winds from China, while mesospheric winds blowing over Japan are moving in a southeasterly direction, which would blow radioactive fallout to the Pacific Ocean.
Saying that it would monitor the situation closely as climate and wind patterns tend to change rapidly during the spring, the bureau predicted that if radiation continues to leak from the Fukushima plant’s crippled reactors, the risk of radioactive pollution reaching Canada and the west coast of the US would increase.
Separately, AEC Deputy Minister Shieh Der-jhy (謝得志) said the council decided to calculate the worst-case scenario after it was bombarded with questions from both legislators and the public since the first hydrogen explosion was reported at the Fukushima plant last week.
Based on the AEC’s analysis, Fukushima is about 2,200km from Taiwan, and the wind is blowing at 5m per second. Assuming all 10 nuclear reactors at the two nuclear power plants in Fukushima melt down, people in Taiwan would accumulate a total of 7.2 millisieverts (msv) of radiation within two days.
The accumulated radioactive exposure over seven days would top 25.5 msv.
The figures are below the government standards that require people to remain indoors, at 10msv, and to evacuate, which is 50msv.
Shieh emphasized that 1 sievert equals 1,000 msv, and 1 msv equals 1,000 microsieverts (μsv), adding that one has to be careful about the units being used when discussing radiation levels. He said cancer patients receive 2 sieverts during each chemotherapy session, whereas those undergoing a computerized tomography on a coronary artery would accumulate 16msv each time.
Additional reporting by CNA