As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has...As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has been accumulated mainly in marine sediments, because sea is about 80% of planet surface, and solid fission products released by nuclear explosions are transported by wind first and then by rain to liquid and solid portions on earth, while gaseous fission products are diffused in the atmosphere. In this way, heavy, high yielding fission products, such as 137Cs, get marine sediments, where they are found mixed with heavy radioactive natural elements such as U, Th and their also radioactive decay products. But since alkaline are so abundant on earth, it is also found natural radioactive isotope 4~K, 0.0118% of isotopes forming K element, with half life 1.28 ~ l09, in the time range of planet age and elements origin. So, one easy way to assess both the importance and evaluation of radioactive contamination at global scale should be to establish a RCF （radioactive contamination factor） as a percentage of 137Cs contaminant radioactivity in marine sediments, compared to 4~K natural radioactivity present from the very beginning of earth, both expressed as Bq per gram of sediment. In the frame of these rather general considerations, a research project has started in Mexico whose varied purposes are： to characterize sea regions in both vast littorals in the country, by its natural 4~K radioactivity present in sea salts, as well as to determine if 137Cs traces produced by recent radioactive contamination have reached their coasts. Also, to assess the 137Cs traces already present in marine sediments as a result of more than two thousand nuclear test explosions performed till now, rather than contamination produced by four main accidents in nuclear reactors during the last 60 years. It is proposed a radioactive contamination factor obtained from samples taken up in both coasts during the last two years, which should be very useful in two ways： first to assess the real danger of radioactive contamination already present by comparing with natural radioactivity, and second to assess the growth, equilibrium or drop of radioactive contamination, given that nuclear energy is still the best option to solve the large energy demand foreseen in the near future.展开更多
Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irra...Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irradiation facility for research the goal of this paper is to show a case study of application of nuclear security and nuclear security culture code of contact in irradiation facility using cobalt 60. And it will show the necessary work done to achieve the goal of protection of radioactive material and continue working in safe conditions. This objective could not be achieved without the collaboration of all department involved in security and nuclear safety. In this work we applied the nuclear security and nuclear security culture procedures in order to define the type of system used to achieve the global objective in accordance with Global Threat Reduction Program to reduce the threat of a RDD （Radiological Dispersion Device） in collaboration with The United States Department of Energy＇s NNSA （National Nuclear Security Administration）. The objective of this paper is to share a local experience in upgrading security with return of experience in practice and very good collaboration with general direction of national security and all departments involved in security and nuclear safety.展开更多
An opportunity to use laser radiation as a means to reduce negative aftermath of acute and prolonged exposure to ionizing radiation was checked. The mice were exposed to γ- rays of ^60Co （whole body irradiation） in...An opportunity to use laser radiation as a means to reduce negative aftermath of acute and prolonged exposure to ionizing radiation was checked. The mice were exposed to γ- rays of ^60Co （whole body irradiation） in the dose of 7 Gy （the transitional clinical form of the acute radiation sickness）. The dose rate at acute irradiation was 1.14 Gy/min, and at prolonged exposure, 0.027 Gy/min. Laser radiation in the dose l mJ/cm^2 was used to irradiate only the back of a mouse. First, the mice were exposed to γ-radiation, then to laser radiation. The time interval between two types of irradiation did not exceed 30 min. It was shown that the radiation protection of mice with laser radiation is possible at exposure to ionizing radiation in a wide dose interval and can reduce negative after-effects of both the acute and prolonged radiation exposure.展开更多
Environment and safety analysis of test blanket module （ TBM ） is an important part of ITER safety design process. The aim is to ensure that the TBM do not adversely affect the safety of ITER and environment around ...Environment and safety analysis of test blanket module （ TBM ） is an important part of ITER safety design process. The aim is to ensure that the TBM do not adversely affect the safety of ITER and environment around ITER. Accurate calculations of all radioactivity and potential harmfulness are very important to environment and safety analysis, nuclear waste disposing and the reactor running, and so on.展开更多
A large amount of radioactivity was released into the environment after the Fukushima nuclear accident （FNA） in Japan in 2011. This radioactivity had a significant impact on the global environment, and there was muc...A large amount of radioactivity was released into the environment after the Fukushima nuclear accident （FNA） in Japan in 2011. This radioactivity had a significant impact on the global environment, and there was much public concern about its effects. The subsequent assessment of the FNA and the environmental remediation required are proving to be long and complicated tasks. The assessments are based on the radioactive source terms for the FNA, which determine the level of damage caused by the nuclear accident. We investigated the radioactive source terms from three aspects： the amount and composition of the radionuclides; the activity and atomic ratio of the radionuclides; and comparison with other historical events. The total amount of radioactivity, excluding the radioactive noble gases （85Kr and 133Xe）, released by the FNA was about 10% of that released by the Chernobyl nuclear accident in 1986 and 〈1%o of the global fallout from the atmosphere nuclear explosion. However, the FNA was the most serious nuclear accident in terms of radioactive pollution of the marine environment. The recovery actions carried out after the FNA have been evaluated and the environmental impacts of the FNA are discussed.展开更多
文摘As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has been accumulated mainly in marine sediments, because sea is about 80% of planet surface, and solid fission products released by nuclear explosions are transported by wind first and then by rain to liquid and solid portions on earth, while gaseous fission products are diffused in the atmosphere. In this way, heavy, high yielding fission products, such as 137Cs, get marine sediments, where they are found mixed with heavy radioactive natural elements such as U, Th and their also radioactive decay products. But since alkaline are so abundant on earth, it is also found natural radioactive isotope 4~K, 0.0118% of isotopes forming K element, with half life 1.28 ~ l09, in the time range of planet age and elements origin. So, one easy way to assess both the importance and evaluation of radioactive contamination at global scale should be to establish a RCF （radioactive contamination factor） as a percentage of 137Cs contaminant radioactivity in marine sediments, compared to 4~K natural radioactivity present from the very beginning of earth, both expressed as Bq per gram of sediment. In the frame of these rather general considerations, a research project has started in Mexico whose varied purposes are： to characterize sea regions in both vast littorals in the country, by its natural 4~K radioactivity present in sea salts, as well as to determine if 137Cs traces produced by recent radioactive contamination have reached their coasts. Also, to assess the 137Cs traces already present in marine sediments as a result of more than two thousand nuclear test explosions performed till now, rather than contamination produced by four main accidents in nuclear reactors during the last 60 years. It is proposed a radioactive contamination factor obtained from samples taken up in both coasts during the last two years, which should be very useful in two ways： first to assess the real danger of radioactive contamination already present by comparing with natural radioactivity, and second to assess the growth, equilibrium or drop of radioactive contamination, given that nuclear energy is still the best option to solve the large energy demand foreseen in the near future.
文摘Around the world, radioactive sources have been widely used for decades to benefit humankind; industry food; health, etc. However, the malicious use of radiological sources poses a significant threat globally. As Irradiation facility for research the goal of this paper is to show a case study of application of nuclear security and nuclear security culture code of contact in irradiation facility using cobalt 60. And it will show the necessary work done to achieve the goal of protection of radioactive material and continue working in safe conditions. This objective could not be achieved without the collaboration of all department involved in security and nuclear safety. In this work we applied the nuclear security and nuclear security culture procedures in order to define the type of system used to achieve the global objective in accordance with Global Threat Reduction Program to reduce the threat of a RDD （Radiological Dispersion Device） in collaboration with The United States Department of Energy＇s NNSA （National Nuclear Security Administration）. The objective of this paper is to share a local experience in upgrading security with return of experience in practice and very good collaboration with general direction of national security and all departments involved in security and nuclear safety.
文摘An opportunity to use laser radiation as a means to reduce negative aftermath of acute and prolonged exposure to ionizing radiation was checked. The mice were exposed to γ- rays of ^60Co （whole body irradiation） in the dose of 7 Gy （the transitional clinical form of the acute radiation sickness）. The dose rate at acute irradiation was 1.14 Gy/min, and at prolonged exposure, 0.027 Gy/min. Laser radiation in the dose l mJ/cm^2 was used to irradiate only the back of a mouse. First, the mice were exposed to γ-radiation, then to laser radiation. The time interval between two types of irradiation did not exceed 30 min. It was shown that the radiation protection of mice with laser radiation is possible at exposure to ionizing radiation in a wide dose interval and can reduce negative after-effects of both the acute and prolonged radiation exposure.
文摘Environment and safety analysis of test blanket module （ TBM ） is an important part of ITER safety design process. The aim is to ensure that the TBM do not adversely affect the safety of ITER and environment around ITER. Accurate calculations of all radioactivity and potential harmfulness are very important to environment and safety analysis, nuclear waste disposing and the reactor running, and so on.
基金China Polar Science Strategy Foundation(Grant No.20120316)Tsinghua University Initiative Scientific Research Program(Grant No.20111080965)the National Natural Science Foundation of China(Grant Nos.11205094&41106167)
文摘A large amount of radioactivity was released into the environment after the Fukushima nuclear accident （FNA） in Japan in 2011. This radioactivity had a significant impact on the global environment, and there was much public concern about its effects. The subsequent assessment of the FNA and the environmental remediation required are proving to be long and complicated tasks. The assessments are based on the radioactive source terms for the FNA, which determine the level of damage caused by the nuclear accident. We investigated the radioactive source terms from three aspects： the amount and composition of the radionuclides; the activity and atomic ratio of the radionuclides; and comparison with other historical events. The total amount of radioactivity, excluding the radioactive noble gases （85Kr and 133Xe）, released by the FNA was about 10% of that released by the Chernobyl nuclear accident in 1986 and 〈1%o of the global fallout from the atmosphere nuclear explosion. However, the FNA was the most serious nuclear accident in terms of radioactive pollution of the marine environment. The recovery actions carried out after the FNA have been evaluated and the environmental impacts of the FNA are discussed.
