Measurement of (238)U, (228)Ra, (226)Ra, (40)K and (137)Cs in foodstuffs samples collected from coastal areas of China.

This study represents a total of 245 samples collected. The activities of (238)U, (228)Ra, (226)Ra, (40)K and (137)Cs were determined in samples of vegetables, tea, cereal (rice, wheat and corn), meat, poultry, freshwater product, seafood and seaweed that collected from the 30km safety zone of the Nuclear Power Plants (NPPs) area. All the samples radionuclide activities were quantified by using High Purity Germanium (HPGe) gamma spectrometry. The geometric mean concentrations (Bqkg(-1) wet weight) for (238)U, (228)Ra, (226)Ra, (40)K, and (137)Cs in all investigated foodstuffs samples, are 0.13, 0.16, 0.11, 68 and 0.02, respectively. The arithmetic mean concentrations (Bqkg(-1) wet weight) for (238)U, (228)Ra, (226)Ra, (40)K, and (137)Cs in all investigated foodstuffs samples, are 0.34, 0.65, 0.32, 111 and 0.09, respectively. Results of this study were compared with others, the measured values are the same with those of a previous investigation. Radiation doses due to the consumption of these foodstuffs to humans are estimated to comprise around 37-46% of the annual dose limit for public.

Intercomparison of γ-spectrometry analysis of radionuclides between China and Japan in 2012-2013.

An intercomparison of γ-spectrometry measurement and analysis was organized by the Japan Chemical Analysis Center (JCAC), the National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention (NIRP, China CDC), and the Radiation Monitoring Technical Center of Ministry of Environmental Protection, Chinese (RMTC). The main objective of this study was to assess the γ-spectrometry measurement and analysis technology. The JCAC completed the collection and preparation of soil and powdered rice samples. Three laboratories compared the measurement of seven radionuclides that included two samples of (214)Pb, (214)Bi, (208)Tl, (228)Ac, (40)K, (137)Cs, and (134)Cs with γ-spectrometry. During the studies conducted at the laboratory, the calculated value En was found to be the total uncertainty data of the reported activity. Except (134)Cs in powdered rice sample, the calculated En between each of the two laboratories was <1. The measurement results are acceptable except (134)Cs; therefore, measurement results in the three laboratories were consistent within a certain range except in the case of (134)Cs. Although there is a need to improve the accuracy of measurements and analysis of (134)Cs, an intercomparison was conducted of the tested levels on radionuclide analyzed in the three laboratories.

A review of nationwide radioactivity comparisons on gamma-ray spectrometry organized by the NIRP, China.

Six comparison exercises on radioactivity measurement by γ-spectrometry have been organized by NIRP in China since 2007. The type of measured nuclides changed from natural to man-made over this period. A total of 188 samples were prepared and distributed to 39 different participating laboratories and 528 radionuclide assays have been performed. A perceptible laboratory performance improvement was observed with the average percentage of acceptable scores being 87% in 2008, increasing to 92% in 2012.

Radioactivity analysis following the Fukushima Dai-ichi nuclear accident.

A total of 118 samples were analyzed using HPGe γ-spectrometry. (131)I, (134)Cs, (137)Cs and (136)Cs were detected in aerosol air samples that were collected 22 days after the accident with values of 1720 µBq m(-)³, 247 µBq m(-)³, 289 µBq m(-)³ and 23 µBq m(-)³, respectively. (131)I was detected in rainwater and soil samples and was also measurable in vegetables collected between April 2 and 13, 2011, with values ranging from 0.55 Bq kg(-1) to 2.68 Bq kg(-1). No (131)I was detected in milk, drinking water, seawater or marine biota samples.

Assessment of radionuclide level in topsoil samples for partial areas of Tibet, China.

By using high-purity germanium gamma spectroscopy, specific activities of naturally occurring and man-made radionuclides were determined in topsoil samples collected from Nyingch, Lhasa and Xigazê of Tibet Autonomous Region, China. The average activity concentrations of (226)Ra, (232)Th and (40)K were 25.1 ± 0.7, 67.1 ± 2.8 and 608.6 ± 12.9 Bq kg(-1), respectively. The activity concentration of (137)Cs was found to vary from <0.3 (minimum detection concentration) to 46.2 Bq kg(-1) with an average of 4.3 ± 0.5 Bq kg(-1). By using the results of (226)Ra, (232)Th and (40)K in the sampled soils, the average outdoor gamma dose rate in air was calculated as 77.5 ± 23.2 nGy h(-1). Furthermore, the average outdoor annual effective dose from terrestrial radiation was 0.10 mSv. The external hazard index in this work varied from 0.20 to 0.70 with an average of 0.40 ± 0.14. The external exposure from terrestrial radiation will not pose any significant radiological threat to the population resident in the studied areas.

Inter-comparison exercise for determination of (226)Ra, (232)Th and (40)K in soil and building material.

A nationwide inter-comparison exercise for the determination of activity concentration of (226)Ra, (232)Th and (40)K in soil and building material was organized by the National Institute for Radiological Protection (NIRP), CDC, China. The primary purpose of this work was to assess the accuracy and precision of gamma-spectrometry analyses. Activity concentrations of (226)Ra, (232)Th and (40)K were determined by gamma-ray spectrometry in accordance with established inter-comparison procedures. A total of 15 laboratories participated in this programme. All participants reported their comparison results for a total of 87 data sets for three nuclides in soil and building material. The overall measurement results of samples for inter-comparison showed a good agreement with the reference values, with nearly 87% of the participants producing acceptable results. Some influential factors in measurement comparisons are also discussed in this paper on the basis of reported results.

Retrospection of recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area of North China using Cesium-137.

The Luanhe River Source Area belongs to typical semi-arid, agro-pastoral ecotone of North China. It is very important for the prevention and treatment of soil erosion in North China to analyze and evaluate quantitatively the recent 30-year changes in the process of soil wind erosion in this area. Based on long field observations, soil samples from different depths in a representative wind-deposited soil profile in the Luanhe River Source Area were collected. Then the (137)Cs activity of soil samples from different depths in the soil profile was determined using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCAM-100), and their soil properties, such as the soil particle fraction and so on, were analyzed. According to the detected (137)Cs activity of different depths, a continuous time sequence of the wind-deposited soil profile in the study area was established. Furthermore, through assumption on a soil relative wind erosion intensity index (SWEI), recent 30-year changes in the process of soil wind erosion in the Luanhe River Source Area were retrospected . The analysis results revealed that weaker soil wind erosion occurred in the study area from the 1970s to the early 1980s and from the late 1980s to the mid to late 1990s. Conversely, intense periods of soil wind erosion occurred in the mid-1980s and from the late 1990s to 2002.