Take iodine 12 hours before fallout

December 1, 2012

Taking iodine before fallout hits is key: NRA

Kyodo

http://www.japantimes.co.jp/text/nn20121201a2.html

The Nuclear Regulation Authority released Friday the results of a computer simulation on how the use of iodine tablets by people around nuclear plants can protect their thyroids from excessive exposure to radiation in the event of a severe catastrophe.

The NRA's estimate, compiled by the government-affiliated Japan Atomic Energy Agency, shows that taking iodine before large fallout is released would have a positive effect, particularly for people within 30 km of a crippled plant.

The Japan Atomic Energy Agency also recommended that people within 5 km of a plant evacuate immediately in the event of a disaster and not wait until radioactive materials actually start to escape.

The agency reported its assessment to a panel set up under the NRA in hopes it will help local governments craft effective disaster mitigation plans based on guidelines compiled since the Fukushima crisis started.

The guidelines feature special disaster preparations for people living within 30 km of a nuclear facility. The analysis is based on the assumption that a 1.1 million kw reactor releases radioactive substances at around the same level as those seen in the Fukushima meltdowns.

In its model, a massive radiation leak starts 27 hours after an emergency occurs at a plant and lasts for seven hours.

The amount of radiation affecting people 5 to 30 km radius from the plant could exceed International Atomic Energy Agency criteria for taking thyroid protection — 50 millisieverts in the first seven days — even if they stay indoors for two days before evacuating beyond the 30-km line. But when taking iodine pills 12 hours before the release of radioactive substances, their exposure is expected to drop below the benchmark line.

November 30, 2012

Taking iodine before release of radioactivity helps reduce exposure

http://mainichi.jp/english/english/newsselect/news/20121130p2g00m0dm077000c.html

TOKYO (Kyodo) -- A Japanese government affiliate said Friday that taking iodine tablets before large amounts of radioactive substances are released in the event of a nuclear plant disaster would help people living within 30 kilometers of the plant to protect their thyroids from excessive exposure.

The analysis by the Japan Atomic Energy Agency also recommended that people within a 5 km-radius of the plant evacuate before the release of radioactive materials begins in such severe cases as that at the Fukushima Daiichi complex.

The agency reported its assessment at a panel set up under the Nuclear Regulation Authority, the country's nuclear regulatory body, hoping it will help local governments craft their own nuclear disaster mitigation plans based on guidelines compiled in the wake of the nuclear crisis.

The guidelines feature special preparations for nuclear disasters for people living within a 30-km radius of nuclear plants.

The analysis is based on the assumption that a 1.1 million kilowatt reactor releases radioactive substances at around the same level as those seen in the Fukushima disaster.

The release of such massive amounts of radiation is presumed to start 27 hours after an emergency occurs at the plant and last for seven hours.

According to the JAEA, the amount of radiation affecting people living within a 5-30 km radius may exceed International Atomic Energy Agency criteria for taking thyroid protection -- 50 millisieverts in the first seven days -- even if they stay indoors for two days before evacuating to outside the 30-km circle.

But when taking iodine pills 12 hours before the release of radioactive substances, their exposure is expected to drop below the benchmark line.

The analysis also said that evacuation before such massive releases of radioactive substances would be effective for people living within the 5-km zone in order to keep the exposure to their whole body below 100 millisieverts, an IAEA-set limit where evacuation is recommended.

But those within a 5-30 km zone do not necessarily have to do likewise, the analysis said.

The benchmark was not exceeded when people within a 5-10 km zone stayed inside concrete facilities for two days and then moved outside the 30-km circle, nor for people within a 10-30 km zone who remained indoors for two days.