241Am and 137Сs in the Khoiniki district of Belarus: updated radiological assessment of the local existing exposure situation

The results covered in this paper relate to the “Khoiniki” research sub-unit of a larger-scale sequence of studies focused on the local assessments of the present-day 241Am and 137Cs concentrations in the soils and locally produced foods, with the estimation of the public internal radiation doses in the residential areas of the Gomel region of the Republic of Belarus most closely adjacent to the ChNPP resettlement zone. The objective was to make a conservative estimate of a committed annual dose of internal exposure from 241Am and 137Сs received by the villagers of 96 farmsteads in 30 settlements of the private sector of Khoiniki countryside through both, inhalation and consumption of local foodstuffs. The results obtained in this study include an update of the existing contamination levels of 241Am and 137Сs present in the local soils and foods grown or produced in private backyards and households. 241Am in food samples was determined by alpha-spectroscopy radiochemical analysis with the use of selective extraction-chromatographic resins. Gamma-spectrometry techniques were used to measure 241Am in soil samples and 137Сs in soil and food samples. Based on our findings, the present-day deposition density of 241Am in the soils does not exceed 4 kBq/m2 , while the values of 137Cs contamination are by one to two orders of magnitude higher than that of 241Am and vary between 30 and 500 kBq/m2 . Generally, the values of activity concentration of 241Am detected in local soils are well within 10 Bq/kg in the majority of inspected villages, with the exception of three sites where higher levels of 241Am contamination is soils were detected ranging from 14 to 16 Bq/kg. The ambient dose rates in the countryside range from 0.05 to 0.38 μSv/hour, with the average of 0.15 μSv/hour. No cases of 137Сs contamination above the established reference levels of 80, 100 and 90 Bq/ kg have been found in the local food samples of, respectively, potatoes, vegetables (incl. roots and tubers) and grains. The content of 241Am in the staple foods produced in the area varies from single digits to tenths of mBq/ kg, which is less by three orders of magnitude than 137Сs activities concentrationd found in the same staples. Of the two pathways contributing to the local committed internal exposure from 241Am, the dominant one is through inhalation (0.006–0.038 mSv/year) prevailing over the consumption pathway of this same radioisotope by at least one order of magnitude. At the time of gardening and other household field works, the existing levels of 241Am contamination in soils are estimated to produce from 85 to 98% of the internal radiation dose received by individuals from inhaling the total of 241Am and 137Сs. The maximum committed annual doses of internal exposure from 137Сs are estimated to be above 1 mSv/year in 6 out of 30 villages engaged in our study. At the same time, the estimated internal radiation dose due to 241Am does not surpass 0.04 mSv/year. The 137Сs major contribution to the internal exposure of villages in the Khoiniki countryside is through food consumption.

Исследование концентрации радионуклидов в колодцах, используемых в качестве питьевой воды в северной Нигерии. На примере мегаполиса Джос

The increasing health effects of nuclear radiation occasioned by the enhanced human activities in the environment necessitated the need for constant investigation and assessment of radiological impact on the general populace within a confined area. Based on this, Twenty two (22) (Hand dug and motorized) well water samples were collected from various locations distributed across Jos Metropolis, Jos North LGA, Plateau State, Nigeria and analyzed for the concentration activity of these radionuclides (40K, 210Pb, 224Ra, 232Th, 238U) using radiochemical analysis technique, a high resolution gamma ray Spectrometry and a radon emanometry technique. The estimated mean concentration activity of 40K, 210Pb, 224Ra, 232Th and 238U in well water samples use as drinking water were determined. The mean concentration ranges from 1.36±0.51 Bq/l to 5.75±1.30 Bq/l. The mean concentration of 40K in well water samples ranges from 3.80±1.19 Bq/l to 2.05±0.30 Bq/l. The mean concentration of dissolved 224Ra in well water samples collected varies from 5.75±1.30 Bq/l to 1.95±0.58 Bq/l. 210Pb has an average concentration of 2.68 ± 0.80 Bq/l to 1.97±0.87 Bq/l. 232Th and 238U had average concentrations of 3.09 ± 0.57 Bq/l to 1.89±0.24 Bq/l and 5.41 ± 1.37 Bq/l to 1.36±0.51 Bq/l respectively. 210Pb and 224Ra were slightly above the recommended limits of 0.10 Bq/l and 1.00 Bq/l respectively, this can be attributed to the geological formation of the sampled area. 232Th and 238U where within the accepted standard limits of 1.00 Bq/l and 10.00 Bq/l recommended value by WHO (World Health Organization) and ICRP (International commission on radiological protection). Activity concentrations of measured radionuclides are in general decreasing in this order: 238U > 40K > 224Ra > 232Th > 210Pb for well water samples within Jos North LGA, respectively. Растущее воздействие ядерной радиации на здоровье, вызванное усилением деятельности человека в окружающей среде, обусловило необходимость постоянного исследования и оценки радиологического воздействия на население в пределах ограниченной территории. Было отобрано двадцать два образца колодезной воды из различных мест, распределенных по мегаполису Джос, Нигерия, и проанализированы на активность радионуклидов (40K, 210Pb, 224Ra, 232Th, 238U) с использованием метода радиохимического анализа, гамма-спектрометрии высокого разрешения и метода радоновой эманометрии. Определены средние концентрации радионуклидов в образцах воды из скважин, используемых в качестве питьевой воды. Средняя концентрация 40K колеблется от 3,80±1,19 Бк/л до 2,05±0,30 Бк/л. Средняя концентрация 224Ra варьируется от 5,75±1,30 Бк/л до 1,95±0,58 Бк/л. 210Pb от 2,68±0,80 Бк/л до 1,97±0,87 Бк/л. 232Th и 238U имели средние концентрации от 3,09±0,57 Бк/л до 1,89±0,24 Бк/л и от 5,41±1,37 Бк/л до 1,36±0,51 Бк/л. 210Pb и 224Ra были немного выше рекомендуемых пределов 0,10 Бк/л и 1,00 Бк/л, это может быть связано с геологическим строением отобранной области. 232Th и 238U находились в пределах принятых стандартных пределов 1,00 Бк/л и 10,00 Бк/л, рекомендованных ВОЗ и МКРЗ.

Development of 3H, 14C, 41Ca, 55Fe, 63Ni radiochemical analysis methods in activated concrete samples

Development of 3H, 14C, 41Ca, 55Fe and 63Ni radiochemical analysis methods were carried out independently by two laboratories using both inactivate and activated concrete samples. Two preliminary radioanalytical procedures for the non-volatile radionuclides (41Ca, 55Fe, 63Ni) and one Thermal oxidation method for the volatile radionuclides (3H, 14C) were developed. The difficulties in the method development and analysis of results are discussed.

Plutonium in Manhattan Project workers: Using autopsy data to evaluate organ content and dose estimates based on urine bioassay with implications for radiation epidemiology

Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results. Methods The comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries. Results Post-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of 239Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average, 196±193%; inclusion of follow-up urine measurements in analyses decreased the mean bias to 0.6±36.3%. Cumulative absorbed doses for the liver, red marrow, bone surface, and brain were calculated for the actual commitment period. Conclusion On average, post-exposure urine bioassay results were in good agreement with post-mortem tissue analyses and were more reliable than results of urine bioassays collected during the exposure.

Intercomparison exercise on difficult to measure radionuclides in activated concrete—statistical analysis and comparison with activation calculations

This paper reports the results obtained in a Nordic Nuclear Safety Research project during the second intercomparison exercise for the determination of difficult to measure radionuclides in decommissioning waste. Eight laboratories participated by carrying out radiochemical analysis of 3H, 14C, 36Cl, 41Ca, 55Fe and 63Ni in an activated concrete. In addition, gamma emitters, namely 152Eu and 60Co, were analysed. The assigned values were derived from the submitted results according to ISO 13,528 standard and the performance assessments were determined using z scores. The measured results were compared with activation calculation result showing varying degree of comparability.

Optimization of 210Po determination in soil

In recent years, naturally occurring radioactive materials (NORM) have become an important topic from the perspective of environmental protection. The list of isotopes that should be monitored in the environment is constantly growing as new amendments to international legislation are introduced. One of the often studied NORM elements is 210Po. In this study, a process of elaborating of a new method of 210Po determination in soil was presented. In the proposed method, several analytical aspects, like the influence of silica decomposition or optimization of an electrode material, were revised. The obtained procedure allows performance of complete radiochemical analysis in a single day, with the chemical efficiency of over 85% and great reduction of costs. Further, the influence of the use of phosphate fertilizers on polonium concentration in soil was also confirmed.

DISTRIBUTION OF RADIONUCLIDES IN NATURAL WATERS OF NORTHERN KAZAKHSTAN AND ASSESSMENT OF WATERBORNE DOSES IRRADIATION OF POPULATION

The population of the Earth is exposed to external and internal radiation every day. Radiation doses differ over a wide range of cosmic radiation levels and the content of natural and anthropogenic radionuclides in the lithosphere, hydrosphere, atmosphere and biosphere. Ionizing radiation and radionuclides of natural and artificial origin inevitably causes exposure, increasing the probability of adverse health effects. Suppose the dose of radiation is low and is exposed for a long period of time (low power). In that case, the risk is significantly reduced, since the likelihood of repair of damaged tissues increases. However, there is a risk of long-term consequences, such as cancer, which can manifest in years or even decades. The paper aims to research the natural factors in the formation of radioactivity in the natural waters of Northern Kazakhstan and assess waterrelated doses to the population. The leading research methods for this issue are radiometric and radiochemical methods of analysis. Selective radiochemical analysis was used to determine the radionuclides of uranium, thorium, radium, lead, cesium and strontium, and a radiometer was used to determine radonuclides. During the study, 166 water sources over the past 5 years were analysed and systematized. The research object was drinking water sources of the population of Ayyrtau, Tayinsha, Yesil districts, and Musirepov district of the North Kazakhstan region. Four types of drinking water sources were investigated: well water, borehole water, spring water, borehole water used for centralized water supply. When calculating the dose of internal exposure, the data of the annual radiochemical analysis of various fresh water sources of four districts of the North Kazakhstan region from 2011 to 2016 were used.

The effects of chronic diseases on plutonium urinary excretion in former workers of the Mayak Production Association

The radiochemical analysis of plutonium activity in urine is the main method for indirect estimation of doses of internal exposure from plutonium incorporation in professional workers. It was previously shown that late-in-life acute diseases, particularly those that affect the liver, can promote accelerated rates of release of plutonium from the liver with enhanced excretion rates. This initial study examines the relationships of some chronic diseases on plutonium excretion as well as the terminal relative distribution of plutonium between the liver and skeleton. Fourteen cases from former workers at the Mayak Production Association (Mayak PA) who provided from 4–9 urine plutonium bioassays for plutonium, had an autopsy conducted after death, and had sufficient clinical records to document their health status were used in this study. Enhanced plutonium excretion was associated with more serious chronic diseases, including cardiovascular diseases and other diseases that involved the liver. These chronic diseases were also associated with relatively less plutonium found in the liver relative to the skeleton determined by analyses conducted after autopsy. These data further document health conditions that affect plutonium biokinetics and organ deposition and retention patterns and suggest that health status should be considered when conducting plutonium bioassays as these may alter subsequent dosimetry and risk models.