ABSTRACT
Objective To ensure the accuracy of gamma spectrometer in our laboratory for the analysis of radionuclides in samples and to improve the laboratory personnel’s ability to perform analyses of radionuclides. Methods Our laboratory had continuously participated in the national assessments of gamma spectrometry of radionuclides organized by the Chinese Center for Disease Control and Prevention. The samples were measured by a high-purity germanium gamma spectrometer (GEM-MX7080P4). An analysis was performed on the results of the gamma spectrometry assessments from 2014 to 2021. Results Our laboratory had an overall qualified rate of 100% (8/8) and an overall excellent rate of 39% (3/8) in the gamma spectrometry assessments from 2014 to 2021. The distribution ranges of RD, Z, U, and Urel for 28 measurements involving radionuclides 208Tl, 228Ac, 232Th, 40K, 238U, and 137Cs were −11.82% to 5.97%, −0.59 to 0.30, 0.02 to 0.92, and 4.33% to 10.49%, respectively. Conclusion The methods used in our laboratory for gamma spectrometry of radionuclides are accurate and the testing reports issued by our laboratory are reliable.
ABSTRACT
Objective To determine the activity concentration of radionuclides for 137Cs and 40K in edible wild mushrooms,and to evaluate the extent of radioactive contamination and ingestion doses to adults from consumption of these wild mushrooms.Methods A total of 33 samples for 18 edible wild mushroom species were collected from natural forest Mangshi,Yunnan province.The activity concentrations of 137Cs and 40K were analyzed by using high-purity germanium (HPGe) gamma spectrometry.Results Except.for one sample that was below the MDA,137Cs artificial radionuclides were detected in other 32 samples,with activity concentration of 137Cs in the range of 0.45-339.58 Bq/kg (dry weight) and an average of 25.47 Bq/kg (dry weight).In regards to 40K in edible mushrooms,all species presented the activity concentrations for this radionuclide and the levels varied from 453.4 to 1 882.6 Bq/kg (dry weight),with an average of 815.1 Bq/kg (dry weight).After species of mushroom with only one sample were eliminated,there was significant difference for 137Cs(F =21.13,P ＜ 0.05) among 6 species of mushroom named Gomphus floccosus (Schw.) Sing.,Boletus edulis bull,Boletus edulis bull,Tylopllus bolloul (Peck) Sing.,Lentinus edodes (Berk.) Sing.and Boletus brunneissimus W.F.Chin,but without significant difference for 40K.Conclusions These 6 different mushroom species have different capacity to retain radionuclides of 137Cs in soil.These wild mushrooms,such as Gomphus floccosus (Schw.) Sing.and Lentinus edodes (Berk.) Sing.have large affinity ability for radionuclides137Cs.The effective dose to adults attributable to consuming these kinds of mushrooms is small and below the level that could cause harm.
ABSTRACT
In order to assess the radioactive level in the environment, the specific activities of 238U, 232Th and 40K were measured by using a gamma ray spectrometer based on a NaI(Tl) detector. The results showed that the specific activities of 238U, 232Th and 40K were 12.846-88.585, 1.304-26.656 and 11.598-2275.896 Bq/kg respectively. The radium equivalent activity was also calculated which varied from 0.893 to 175.244 Bq/kg. The radium equivalent average values were lower than the world average. In general, the highest level of radium equivalent value was in leafy type NPK fertilizers. The urea type had no radionuclide. The specific activity and absorbed dose rate at 1m above the ground surface (nGy/h) after NPK fertilizers agricultural applications were calculated and the maximum value of dose rate was 0.15 percent of the world average outdoor exposure due to terrestrial gamma radiation.
ABSTRACT
Objective To estimate the dose to non-uranium miners from external exposure.Methods Ore samples of non-uranium mines were collected in site and analyzed with gamma spcetrometry,then annual dose to the miners was estimated based on the measured radioactivities of radionuclides.Results Thirty-two ore samples in thirteen mines in seven provinces were collected and analyzed.Among them,radioactivity concentrations in two samples were higher than others,and the annual doses from external exposure to the radionuclides in the two ore samples were estimated to be higher than 1 mSv/a.Conclusions Gamma spectrometry is fit for determining the radionuclides concentrations and its results can be used for estimating dose from external exposure in non-uranium mines.
ABSTRACT
Objective To establish a method for estimating internal dose from aerosol inhalation in non-uranium miners.Methods Aerosol samples in a tunnel in Dongchuan Copper Mine in Yunnan Province were collected by portable high flux air sampler.Radionuclides collected at the sampler filters were analyzed by the gamma spectrometry.Annual committed effective dose due to inhalation of the aerosol dust was estimated using the formula provided by ASTM.Results Radionuclides collected in two aerosol samples were anlayzed,the annual committed effective doses due to inhalation of 1 μm and 5 μm aerosol were estimated.Conclusions The method of using high flux air sampling and gamma spectrometry is explored to estimate the dose from aerosol inhalation.
ABSTRACT
Objective To organize measurement comparison among provincial CDC gamma spectrometry laboratory for verification of the precision and accuracy of the measuring results from each laboratory and to improve the ability and level for radionuclides measurement in building materials.Methods The method for gamma spectrometry measurement comparison was referred to the method of IAEA international comparison in 2002.Results The results of these labs in this comparison agreed with the reference results well.About 50% labs' relative biases were less than 5%,over 80% labs were less than 10%.Conclusions The results of this comparison showed that the analysis method for the radioactivity content in building materials by gamma spectrometry in each lab was credible and meet the request of the standard GB 6566-2001 "Radioactive Nuclide Limit for Building Materials".