چكيده لاتين :
Chernobyl and Fukushima nuclear accidents showed that nuclear accident is not an issue of regional scale and radioactive nuclei disperse and transport faraway under atmospheric conditions. They have a lot of damage, undesirable and dangerous long term effects on the environment and human health. Given the importance of this issue, in this paper, the simulation of atmospheric dispersion, transport and deposition of nuclear materials released from a hypothetical accident in Bushehr nuclear power plant have been studied using HYSPLIT. The hypothetical accident at Bushehr nuclear power plant is based on world's largest nuclear accident, the Chernobyl accident. In this study, it is assumed that the accident in Bushehr nuclear plant occurred on 22 December 2014. Most important radioactive nuclei namely Cesium-137, Iodine-131, Strontium-90, Plutonium-239 and Tellurium-132 are used in this simulation. Release of the radioactive materials is different into the environment. So that, 30% of the cesium-137, 55 % of the Iodine-131, 5 % of the Strontium-90, 3.5 % of the Plutonium-239 and 40 % of the Tellurium-132 contained in the reactor core are released. The accident is controlled for three days. The emission rate of radioactive materials is also different in these days. So, 60 %, 30 % and 10 % of nuclear pollutants are released into the environment, respectively in the first day, the second day and the third day. Given speed and energy of pollutants exit from reactor, they are placed in different heights. The approximate release heights are determined based on the Chernobyl accident. The release heights are 225, 425, 715, 1090, 1575 and 2225 meters. The amount of pollutants that are placed at any height is also different.
Simulation of atmospheric dispersion, transport and deposition of radioactive materials released in the accident is performed for 1, 10, 24, 48, 168, 336 and 720 hours at different levels. In this paper, the atmospheric dispersion, transport and deposition of nuclear pollutants is investigated over Bushehr province, Iran and the world separately. In addition, the hypothetical accident of Bushehr reactor in 22 December 2014 are compared with the hypothetical accidents of Bushehr reactor in 21 March, 22 June and 23 September 2015.
The simulation results show that in the period of one month, the nuclear materials released from the accident polluted Tangestan, Dashti, Dayyer, Kangan, Jam and Asaloyeh more than other regions in Bushehr province and the maximum deposition of nuclear pollutants is in the coastal areas Tangistan.
The simulation results show that a week after the accident, nuclear pollutants are polluted southern, southeastern, eastern and part of northeastern areas of Iran thoroughly and they also affected neighbouring some countries. On the other hand, nuclear materials polluted Red Sea. Two weeks after the event, part of the pollutants entered the continent of America after crossing East Asia and they are deposited in North America. Another part of the pollutants also dispersed in the African continent and after a month of the event they are deposited in South America.
In Iran, Lamerd and Bandar Abbas have the maximum of nuclear pollutants concentration. In Lamerd, on the first day, the maximum concentration of radioactive materials at ground level and the heights 10 meters is and , respectively.
Comparing the hypothetical accident of Bushehr reactor in 22 December 2014 with the hypothetical accidents of Bushehr reactor in 21 March, 22 June and 23 September 2015 show that the dispersion and transport of radioactive materials released from accident of 22 December 2014 is almost similar with the hypothetical accidents of Bushehr reactor in 22 June and 23 September 2015, because the pressure systems have the same effects on Bushehr plant. With passing time, the dispersion and transport of nuclear pollutants is different. But in every three incidents, the most pollution is over the southern regions of Iran. The results of this study under similar atmospheric conditions will be applicable to use in Bushehr nuclear plant emergencies.
