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The peaceful use of nuclear energy has a history of nearly 80 years, and the development of nuclear energy in China has been actively and steadily promoted. Up to now, there have been three major nuclear power plant accidents in human history: Three Mile Island nuclear accident in the United States, Chernobyl nuclear accident in the former Soviet Union and Fukushima nuclear accident in Japan. However, the public in our country knows little about the three nuclear accidents. This paper introduces some books on the three nuclear accidents for the general public, which help the public understand the nuclear accidents from a non-professional point of view.
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Objective To study the 137Cs source term from the Fukushima Daiichi nuclear power plant,based on inverse modeling,so as to provide reference for accident assessment and radiation protection.Methods The 137Cs source term was estimated by means of inverse modeling of nuclear accidents based on variational data assimilation combined with truncated total least squares (TTLS-VAR).The environmental monitoring data was balanced,and the dispersion model operator and monitoring data vector were corrected,in order to reduce the influence from atmospheric dispersion model error,and then improve the accuracy of inverse modeling of source term.Results The total amount of 137Cs released was estimated to be 1.74× 1016-3.73× 1016 Bq,with the highest peak of release rates estimated appearing on March 18,2011 and the average release rate in exceed of 1.00× 1012 Bq/s.The estimated total amount of 137 Cs was close to the data published by IAEA and UNSCEAR.Also,the estimated release sequences were in good consistent with Japanese analytical results of source terms and sequence of events.The highest peak of the estimated release rate curve corresponds to the leakage incident of unit 3.Conclusions In this study,the 137Cs source term from the Fukushima Daiichi nuclear power plant is estimated by using TTLS-VAR inverse modeling,which could provide the basis for accident assessment and radiation protection.
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Since the accident on March 11th 2011 at the Fukushima Daiichi Nuclear Power Station following the Great East Japan Earthquake,huge amount of radionuclide has been released to the surrounding environment.In this study,the environmental monitoring method,γ-ray dose rates,radioactivity in environmental samples,food,wild animals and plants,health situation of residents were summarized.Through summarizing the accident experience of Fukushima Daiichi Nuclear Power Station,this research discussed and analyzed the accident combining with the situation in China.
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Objective To determine the artificial radionuclides levels in environmental samples collected in some areas of China following the Japanese Fukushima nuclear accident,and to evaluate the extent of radioactive contamination.Methods A total of 118 samples including aerosol,water,soil and biological samples were collected and the activity concentrations of 131I, 137Cs and other artificial radionuclides were analyzed by using high-purity germanium (HPGe) γ spectrometry.Results Artificial radionuclides 131I,134Cs,137Cs and 136Cs were detected in the aerosol samples on 2 April,2011 and the activity concentrations were 1720,247,289,and 23 μBq/m3,respectively.Trace amount of 131I was detected in one sample of rain water and two samples of surface soil with concentrations of 2.08 Bq/L,1.82 and 0.59 Bq/kg,respectively.131I was also detected in 18 vegetable samples which were collected from 2 April to 13 April with the range of 0.55 -2.68 Bq/kg.Neither abnormal concentrations of 131I nor 137Cs was detected in milk,drinking water,sea water and marine products samples.Conclusions During the Fukushima nuclear accident,although minute quantities of radionuclides were detected in some samples collected in China,the effective dose for adults attributed to the nuclear accident is extremely small and significantly below the level that could cause harm to the public.
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Objective To monitor the levels of radioactive contamination due to the Japanese Fukushima nuclear accident in Beijing,so as to provide scientific technical information for government to draw effective controlling strategy and processing mechanism.Methods The system of nuclear emergency nmonitoring was started,then the radioactive contamination levels of atmosphere,rain water,surface water and vegetables in Beijing were detected according to the relative survey regulations and technology criterions.Results During the period from 15 to 41 d after the accident,obvious radioactive contamination was found in the atmosphere of Beijing.The maximum radioactivity concentration of 131I ( 5.89 mBq/m3 ) was detected at 22 d after the accident.The radioactivity concentrations of 137Cs and 134Cs were surveyed forming their corresponding peaks at 20 d after the accident,but they were one magnitude lower than the peak value of 131I at least.In addition,the gross β radioactivity level in the water of Chao Bai-he river was verified to be in the range of 0.314 - 0.602 Bq/L. Conclusions The radioactive contamination due to Fukushima nuclear accident has not done visible harm to the public health in Beijing,but monitoring should be continued to observe the long-term effect of the accident.
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Objective To investigate the radiological contamination of body surface for inbound people from Japan to China during Fukushima nuclear accident.Methods According to The guidance for radiological contamination management for body surface issued by Chinese Center for Disease Control and Prevention,for people evacuated from Japan,the body surface monitoring of radiological contamination was performed by the related agencies in main provinces and cities in China. The monitoring data were collected,analyzed and reported to Ministry of Health.Results A total of 432 persons were checked.The monitoring results of 429 cases were close to the background level,while those of three persons were higher than the background level.Conclusions In general,the detected results were as low as the background level.The radiological contamination monitoring of body surface for people from Japan could provide scientific data to relax the horror and panic among them.
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Objective To summarize the analytical results of radioactivity in the food and drinking water nationwide following the Fukushima nuclear accident,and to evaluate its possible contamination to the public health in China.Methods According to the national standard methods and IAEA,FDA correlative references,the scheme was established on sampling and measurements in food and drinking water after the breakout of the accident.The quality control was requested on the sampling,analyses and data report.Results Trace artificial radioactive isotope of 131I was measured in spinach samples on 2 April 2011 in Beijing. Subsequently 131I was found in 10 kinds of growing leaves vegetables (open field)nationwide.The maximum detectable activity of 131I in vegetables was about 3.1 Bq/kg.Since 3 May 2011,the concentration of 131I has been below the detection limits.No artificial radionulide was detectable in all of milk,drinking water and marine products samples during March to December,2011.Conclusions The food and drinking water measurements in China following the Fukushima nuclear accident denoted that the minor amounts of 131I in vegetables might result in very low absorbed dose and induce no impact on human health.The maximum detectable activity of 131I in vegetables was close to that reported in European countries,and much less than that measured in China immediately after the Chernobyl accident in 1986.
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Objective To investigate the environmental impact of the Japanese Fukushima No.1 nuclear power plant accident on radiation levels in some areas of Liaoning province.Methods The emergent monitoring was performed by detecting atmosphere aerosols,precipitations,drinking water,vegetables,milk and seafood by gamma spectrometry analysis and gross activity measurements.Results The fission radionuclides of 131I,134Cs and 137Cs were detected in atmosphere aerosols 20 d after nuclear accident.The rad ionuclides of 131I,134Cs and 137Cs were found existing in atmosphere for 25,4 and 6 d,respectively,with the highest concentrations of 4.6 × 10 3,2.9 × 10-4 and 4.2 × 10-4 Bq/m3,respectively.The man-made fission radionuclides could not be detected in vegetablcs,drinking water and milk from Shenyang city and seafood from Dandong city.Conclusions The atmosphere might be slightly contaminated in Liaoning province due to the nuclear accident,whereas the vegetables,milk and drinking water not contaminated.
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Objective To detect artificial radionuclide content in the spinach and soil in open air vegetable garden in Beijing during Fukushima nuclear accident and to study the radioactive contamination characteristics of the samples.Methods 6 spinach samples and 3 soil samples in open air vegetable garden were obtained through continuously sampling.High-purity germanium (HPGe) γ spectrometry was used to analyze activity concentrations of artificial radionuclide131 Ⅰ etc in these samples.Results Artificial radionuclide 131Ⅰ was detected in the 6 open air spinach samples.Artificial radionuclide 137Cs was detected in 3 vegetable garden soil samples,trace amount of 131 Ⅰ was detected in 1 open-air surface soil sample alone.Conclusions Following the Fukushima nuclear accident,spinach in Beijing's open-air vegetable garden was slightly polluted by artificial radionuclide 131 Ⅰ,with the highest values of pollution appeared around April 4,2011,but it could not cause harm to human health.