Approximate relationship for calculating the dose rate from radioactive fallout

Background:Male hunters in Swedish counties with high fallout of 137Cs after the Chernobyl Nuclear Power Plant (NPP) accident have higher radiation exposure due to higher consumption of game compared with the general population.Methods:Cancer incidence in Sweden was studied in 9 counties with different 137Cs fallout after the Chernobyl NPP accident in 1986. In total, 9,267 cancer cases occurred in hunters and 138,909 cancer cases in non-hunters to 31 December 2015. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated using unexposed hunters, or non-hunters, as reference to study internal radiation exposure or hunter life style, respectively.Results:Directly age standardized total cancer incidence showed an increasing trend in non-hunters. For hunters, the total cancer incidence was significantly lower up to 2001 when the total cancer incidence crossed over the weaker non-hunter trend and remained higher for the following 15 years. IRRs for total cancer in hunters versus non-hunters for each county did not show any clear exposure response pattern. IRRs for hunters versus non-hunters were higher regardless of rural/non-rural status with slightly higher risk estimates for the rural settings. The IRR for hunters was 1.06 (95% CI 1.04–1.08) 1986–2015, representing an excess of 531 cancer cases in hunters.Conclusion:An increased total incidence of cancer was identified for male hunters compared with male non-hunters. No obvious association between cancer and 137Cs from the Chernobyl NPP accident could be identified, although the exposure classification was too crude to exclude such an association.

The time dependence of the absorbed dose rate in air at a distance of 1 m from a patient who was undergoing myocardial perfusion scintigraphy with 201 Tl was measured. The absorbed dose rate was deduced by in situ gamma ray spectrometry using a 'calibrated' portable Ge detector which allows the direct measurement of spectral dose rate distribution in the surroundings of a source without any assumption about the source geometry. The decrease of the absorbed dose rate with time can be expressed by a single exponential decay. The effective and biological half-lives of 201 Tl were estimated to be 63 h and 20 days respectively. The total absorbed dose in air at a distance of 1 m from the patient was found to be 0.03 mGy which, converted to effective dose, gives 0.03 mSv which is small compared with the arithmetic annual mean worldwide, weighted for population, effective dose due to terrestrial gamma rays (0.46 mSv) and cosmic rays (0.38 mSv).

BACKGROUND AND AIM: Male hunters have slightly higher total cancer incidence versus male non-hunters in 9 Swedish counties after the Chernobyl Nuclear Power Plant (NPP) accident in 1986. The aim of this study was to investigate whether the contribution of absorbed dose from the Chernobyl fallout could have influenced the elevated cancer incidence, given that hunters have a higher internal radiation exposure due to consumption of game contaminated with ¹³⁷Cs. METHODS: An algorithm was developed to calculate the total absorbed colon dose as a sum of external and internal absorbed colon dose. The time-integrated total absorbed colon dose was calculated individually for hunters (n=40 874) 1986-2015. Allowing for a 5-year latency period, the age-adjusted Incidence Rate Ratios (IRR) per milliGray (mGy) with 95% Confidence Intervals (CI) were calculated using Poisson regression for the follow-up period 1991-2015. A total of 8 964 cancer cases occurred in the hunter cohort to 31 December 2015. Pre-Chernobyl total cancer incidence in each of the counties was investigated as a potential confounding factor. RESULTS:The mean colon dose was 2.39 mGy with more than half of the absorbed colon dose from internal ¹³⁴Cs and ¹³⁷Cs taken together. No specific cancer site showed a significant increased IRR per mGy. For total cancer the IRR per mGy was 0.995 (95% CI 0.988-1.003). The IRR did not change after adjustment for the pre-Chernobyl total cancer incidence. CONCLUSIONS:Using the total colon dose as proxy for the whole body dose, no dose-dependent increased risk for cancer was observed in hunters, hence the elevated cancer incidence in hunters versus non-hunters could probably not be attributed to intake of ¹³⁷Cs contaminated game after the Chernobyl NPP accident. Future analyses will calculate individual organ absorbed dose and investigate dose-response relationship for those cancer sites. KEYWORDS: incidence, ionizing radiation, environmental epidemiology, exposure assessment, cancer and cancer precursors

An integral expression was derived for calculating the dose rate from a rectangular source which can be reduced to sources having the form of either an infinite plane strip or an infinite plane. Consideration of dose buildup was made by incorporating a dose buildup factor of the Berger form in the equation. Results of calculations of the dose rate from an infinite strip source are presented as a fraction of that from an infinite plane source. The equation has been applied to strip sources varying from 1 to 1000 m in width and for gamma energies ranging from 50 keV to 5 MeV. The application of the equation and data to the calculation of dose rates above a shore or beach surface contaminated by radionuclides released to the environment in liquid effluents from nuclear power stations or other nuclear facilities is discussed.

An area located in the Southern Urals was contaminated in 1949-1956 as a result of radioactive waste releases into the Techa river by the Mayak Production Association. The external dose reconstruction of the Techa river dosimetry system (TRDS-2000) for the exposed population is based on an assessment of dose rates in air (DRA) obtained by modeling transport and deposition of radionuclides along the river for the time before 1952 and by gamma dose rate measurements since 1952. The aim of this paper is to contribute to a verification of the TRDS-2000 external dose assessment. Absorbed doses in bricks from a 130-year-old building in the heavily exposed Metlino settlement were measured by a luminescence technique. By the autumn of 1956 the population of Metlino had been evacuated, and then a water reservoir was created at the village location, which led to a change in the radioactive source geometry. Radiation transport calculations for assumed environmental sources before and since 1957 were performed with the MCNP Monte Carlo code. In combination with TRDS-2000 estimates for annual dose rates in air at the shore of the Techa river for the period 1949-1956 and contemporary dose rate in air measurements, absorbed doses in bricks were calculated. These calculations were performed deterministically with best estimates of the modeling parameters and stochastically by propagating uncertainty distributions through the calculation scheme. Assessed doses in bricks were found to be consistent with measured values within the uncertainty bounds, while their best estimates were approximately 15% lower than the luminescence measurements.

PANTHERE is an industrial simulation tool developed by EDF to calculate γ dose rates in 3D geometry with numerous observation points and radioactive sources.It is composed of three main components: a kernel, a GUI and a database.PANTHERE takes a key role in EDF's ALARA process, enabling to predict dose rates and then organize and optimize operations in high radiation environments.It is used in most EDF engineering units at every stage of a nuclear facility lifecycle: design (EPR TM , for example), operation (maintenance) and dismantling.PANTHERE is verified and validated by comparison with reference Monte-Carlo code TRIPOLI-4® and gamma dose rates experimental measurements.EDF is currently replacing PANTHEREV1 (operational version) by PANTHEREV2.The major improvements are the enhanced computation speed, the unification of the GUI and the shared database for all radiation protection simulation codes used by EDF engineering units (gamma, and in the future beta and neutron radiation).PANTHEREV2's kernel uses the NARMER solver of the CEA, which performs dose rate calculations based on the point-kernel integration method with build-up factors.The GUI is based on the software platform SALOME® of CEA and EDF, and provides improved ergonomy and contains all necessary features as required by radiation protection simulation practices.

1.20 Some Features of Gene Repertoire of IGHV/D/J Rearrangements in Chronic Lymphocytic Leukemia Patients Exposed to Ionizing Radiation due to the Chernobyl Nuclear Power Plant Accident

Ambient gamma radiation study was carried out in South Konkan using thermo luminescent dosimeters (TLDs). A statistical analysis was carried out to understand the distribution of gamma radiation in the study area. The annual effective doses (AEDs) received by the local population from the selected villages were 0.31 and 0.09 mSv year−1 for indoor and outdoor locations, respectively. For indoor conditions, the maximum dose rate occurred for winter season and the minimum occurred in monsoon season while for outdoor conditions the maximum dose rate occurred in spring season and minimum occurred in the monsoon season. The terrestrial radioactivity in the corresponding villages was measured by a HpGe detector. The radiation hazard indices like absorbed dose rate in air (D), radium equivalent activity (Raeq), external hazard index (H ex) and internal hazard index (H in), and AED were calculated using soil radioactivity data. The minimum absorbed dose rate in air (33.97 nGy h−1) corresponds to the Dale village and the maximum (101.86 nGy h−1) corresponds to the Mithgawane village. Radiation hazard indices as Raeq, H ex, and H in were found to be within the limit. The average AED from natural radionuclides was found to be lower than the worldwide value. The AEDs of this study were compared with previous studies carried out worldwide. A positive correlation was observed for the absorbed dose rate in air and the activity concentration of U-238, Th-232, and K-40. A positive correlation between activity concentrations of U-238, Th-232, and K-40 was also observed. The comparison between the AEDs calculated using absorbed dose measured by TLDs and the values calculated from soil’s gamma spectrometry showed some variation in the villages of South Konkan.

After the Chernobyl nuclear power plant accident in 1986, all Member States of the European Union have installed area dose rate monitoring networks so that radiological incidents can be detected quickly. However, the different technical approaches and procedures led to inconsistencies in the area dose rate data. In the last 15 years, the working group 'Environmental Radiation Monitoring' of the European Radiation Dosimetry Group (EURADOS) has performed six pan-European intercomparison exercises for detector systems operated in national dosimetric early warning networks. These intercomparisons aimed at the harmonisation of area dose rate measurements of radiation monitoring stations in Europe. The intercomparisons revealed differences in technical properties of the dose rate monitoring systems as well as in the calibration and measuring methods that led to deviations of measured dose rate values by a factor of 5 or more under the same measuring conditions. As a result of the intercomparisons, the accuracy of dose rate measurements could be improved considerably. Further progress in metrologically correct measurements of area dose rates in the natural environment and necessary steps towards a metrologically sound pan-European system for environmental radiation monitoring will be discussed.

This study presents the first documented evidence of radioactive contamination in Western Abkhazia linked to the Chernobyl Nuclear Power Plant accident. The data obtained show that the level of ¹³⁷Cs radioactive contamination in the study area ranged from 50 to 160 kBq/m² in 1986. This corresponds to contemporary values of 25 to 79 kBq/m² when considering the radionuclide’s half-life. These measurements are highly consistent with data recorded in the adjacent Sochi region, where contamination levels varied between 40 and 185 kBq/m² in 1986. The local spatial variability of ¹³⁷Cs fallout was studied at four reference sites, located in different parts of the Mussera upland. All investigated sites demonstrated moderate variability, with value ranges of 17–25%. This heterogeneous distribution pattern is attributed to a combination of factors, including local topography, atmospheric deposition characteristics, and anthropogenic influence. Measurements of ambient dose equivalent rates ranged from 0.01 to 0.05 μSv/h. While no direct correlation was found between dose rates and the age or genesis of the underlying bedrock, a clear relationship was established between dose rates and terrain morphology. Elevated dose rates were consistently recorded in erosional landforms within topographically dissected areas. Analysis of peat cores from the Pitsunda Peninsula lagoon provided conclusive evidence of the Chernobyl disaster’s impact on Western Abkhazia, with a measured ¹³⁷Cs inventory of 20.7 kBq/m² (equivalent to 49.5 kBq/m² when corrected to 1986 values). Application of the non-equilibrium ²¹⁰Pb dating method yielded a peat accumulation rate of 0.1 cm/year. The Chernobyl accident resulted in a significant release of 137 Cs, leading to widespread radioactive fallout. This document assesses the 137 Cs inventory and its impact on ambient dose rates in the affected regions.

The absorbed dose rates in air due to terrestrial radionuclides were estimated from aerial gamma spectrometric data for an area of 48,600 km2 in Southern Brazil. The source data was the Serra do Mar Sul Aero‐Geophysical Project back‐calibrated in a cooperative work among the Geological Survey of Brazil, the Geological Survey of Canada, and Paterson, Grant & Watson Ltd. The concentrations of eU (ppm), eTh (ppm) and K (%) were converted to dose rates in air (nGy⋅h−1) by accounting for the contribution of each element's concentration. Regional variation was interpreted according to lithotypes and a synthesis was performed according to the basic geological units present in the area. Higher values of total dose were estimated for felsic igneous and metamorphic rocks, with average values varying up to 119±24 nGy⋅h−1, obtained by Anitapolis syenite body. Sedimentary, metasedimentary and metamafic rocks presented the lower dose levels, and some beach deposits reached the lowest average total dose, 18.5±8.2 nGy⋅h−1. Thorium gives the main average contribution in all geological units, the highest value being reached by the nebulitic gneisses of Atuba Complex, 71±23 nGy⋅h−1. Potassium presents the lowest average contribution to dose rate in 53 of the 72 units analyzed, the highest contribution being obtained by intrusive alkaline bodies (28±12 nGy⋅h−1). The general pattern of geographic dose distribution respects well the hypotheses on geo‐physicochemical behavior of radioactive elements.

The absorbed gamma-dose rate in air at a height of 1 m above ground level was calculated from activity concentrations of gamma-emitting radionuclides in arable soil samples collected from eight locations within Sinnar State using the published Dose Rate Conversion Factors. Measurements were carried out using high-resolution gamma-spectrometry. On average, the activity concentrations obtained were 38 +/- 8 ((232)Th), 17 +/- 2 ((226)Ra), 174 +/- 19 ((40)K) and 0.9 +/- 0.2 Bq kg(-1) for the fallout radionuclide (137)Cs. The average value obtained here for (232)Th is slightly higher than the corresponding world-average. The calculated absorbed dose rate in air at a height of 1 m for all sampled locations ranges from 31 to 47 nGy h(-1) with an average value of 39 +/- 7 nGy h(-1) which is characteristic of normal background radiation areas. The corresponding annual effective dose was 47.8 +/- 6 microSv y(-1). The major contribution to the total absorbed dose rate comes from (232)Th, which amounts to 61%. Recalculation of the absorbed dose rate-based gamma-energies of individual nuclides from uranium and thorium decay series and (40)K showed that the greater part of the absorbed dose from the uranium series is due to (214)Bi, whereas for the (232)Th series it is equally attributed to (228)Ac and (208)Tl.

Concentrations of 238U, 232Th, 226Ra, 40K and 137Cs are measured in collected soil samples from various locations in the Thrace region of Turkey. The activity concentrations range from 12.82 to 101.75 Bq kg−1 d.w. (dry weight) for 238U, from 5.16 to 73.34 Bq kg−1 d.w. for 232Th, from 185.54 to 5399 Bq kg−1 d.w. for 40K and from 11.42 to 90.73 Bq kg−1 d.w. for 226Ra. In addition to naturally occurring radionuclides, 137Cs activity concentration is determined between 3.05 and 46.78 Bq kg−1 d.w. for soil samples. Determination of the radiological hazard is achieved through calculations of the external terrestrial gamma dose rate in air (nGy h−1) and annual effective dose rate (mSv year−1) and the results are compared with the similar works in different countries.

A spatial simulation method in.mp4 format was proposed to determine Fukushima radioactive fallout transport and the Absorbed Dose Rate, Annual Effective Dose Equivalent, and Excess Lifetime Cancer Risk were determined for 10 months after the accident (March 11 2011). The findings of this study demonstrate that an appropriate ARIMA model can be applied for radiation dose time-series in the case of nuclear reactor accidents like Chernobyl and Fukushima to predict the future air dose rates, which can provide valuable information in determining the evacuation zones, decontamination processes, and radiation protection progresses. The model forecasted results and the actual observation data in the same period shows a gradual decrease in the air dose rates during the prediction period. Moreover, there is a good agreement between them as the prediction and observation scatter plot follows each other with small variations. These results provide important insights into the predictability of ARIMA models; thus, the models were utilized to forecast the air dose rates for the period (January 2020–October 2020).

Air dose rates were measured inside a car with an ion chamber detector across Fukushima Prefecture from March 19 to 22, 2011. The dose rate along the Tohoku Expressway ranged from 2 to 6 μSv/h. Relatively high values were obtained around Nihonmatsu City. The dose rate dipped to an exceptionally low value inside a tunnel to what was probably the normal background value before the Fukushima nuclear accident. The dose rate in Fukushima City ranged from 2 to 9 μSv/h. High values were obtained in the center of the city. The dose rates along the Banetsu Expressway and in Samegawa Village located in the Abukuma highlands were very low at 1.5–3 and 1 μSv/h, respectively. During our stay in Fukushima, external and internal exposure was evaluated at 0.1 and 0.0327 mSv, respectively. A commercially available GM-tube detector calibrated with a 137Cs standard source was used to determine the status of environmental radioactive contamination caused by the Fukushima nuclear accident. The calibration was achieved with a quadratic correction function for dose rates up to 4 μSv/h. The calibrated GM-tube detector was used for measuring air dose rates and ground surface contamination in East Japan. Measurements were taken inside a car and a bullet train as well as outdoors from March to August 2011. The dose rates measured inside a vehicle along the Tohoku Expressway (in May) and in the Tohoku Shinkansen (in August) were as much as 1.0 and 0.25 μSv/h, respectively. The measurement results agreed well with the official data obtained using a NaI scintillation counter, demonstrating that a calibrated GM-tube detector can be an effective tool for measuring radioactivity.