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1.
Radiat Environ Biophys ; 51(1): 1-14, 2012 Mar.
Article in English | MEDLINE | ID: mdl-21947564

ABSTRACT

Breast cancer risk from radiation exposure has been analyzed in the cohort of Japanese a-bomb survivors using empirical models and mechanistic two-step clonal expansion (TSCE) models with incidence data from 1958 to 1998. TSCE models rely on a phenomenological representation of cell transition processes on the path to cancer. They describe the data as good as empirical models and this fact has been exploited for risk assessment. Adequate models of both types have been selected with a statistical protocol based on parsimonious parameter deployment and their risk estimates have been combined using multi-model inference techniques. TSCE models relate the radiation risk to cell processes which are controlled by age-increasing rates of initiating mutations and by changes in hormone levels due to menopause. For exposure at young age, they predict an enhanced excess relative risk (ERR) whereas the preferred empirical model shows no dependence on age at exposure. At attained age 70, the multi-model median of the ERR at 1 Gy decreases moderately from 1.2 Gy(-1) (90% CI 0.72; 2.1) for exposure at age 25 to a 30% lower value for exposure at age 55. For cohort strata with few cases, where model predictions diverge, uncertainty intervals from multi-model inference are enhanced by up to a factor of 1.6 compared to the preferred empirical model. Multi-model inference provides a joint risk estimate from several plausible models rather than relying on a single model of choice. It produces more reliable point estimates and improves the characterization of uncertainties. The method is recommended for risk assessment in practical radiation protection.


Subject(s)
Breast Neoplasms/epidemiology , Models, Theoretical , Neoplasms, Radiation-Induced/epidemiology , Nuclear Weapons , Adolescent , Adult , Age Factors , Aged , Child , Cohort Studies , Female , Humans , Incidence , Japan/epidemiology , Middle Aged , Survivors , Young Adult
2.
Radiat Environ Biophys ; 46(4): 383-94, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17562061

ABSTRACT

Lung cancer mortality in the period of 1948-2002 has been analysed for 6,293 male workers of the Mayak Production Association, for whose information on smoking, annual external doses and annual lung doses due to plutonium exposures was available. Individual likelihoods were maximized for the two-stage clonal expansion (TSCE) model of carcinogenesis and for an empirical risk model. Possible detrimental and protective bystander effects on mutation and malignant transformation rates were taken into account in the TSCE model. Criteria for non-nested models were used to evaluate the quality of fit. Data were found to be incompatible with the model including a detrimental bystander effect. The model with a protective bystander effect did not improve the quality of fit over models without a bystander effect. The preferred TSCE model was sub-multiplicative in the risks due to smoking and internal radiation, and more than additive. Smoking contributed 57% to the lung cancer deaths, the interaction of smoking and radiation 27%, radiation 10%, and others cause 6%. An assessment of the relative biological effectiveness of plutonium was consistent with the ICRP recommended value of 20. At age 60 years, the excess relative risk (ERR) per lung dose was 0.20 (95% CI: 0.13; 0.40) Sv(-1), while the excess absolute risk (EAR) per lung dose was 3.2 (2.0; 6.2) per 10(4) PY Sv. With increasing age attained the ERR decreased and the EAR increased. In contrast to the atomic bomb survivors, a significant elevated lung cancer risk was also found for age attained younger than 55 years. For cumulative lung doses below 5 Sv, the excess risk depended linearly on dose. The excess relative risk was significantly lower in the TSCE model for ages attained younger than 55 than that in the empirical model. This reflects a model uncertainty in the results, which is not expressed by the standard statistical uncertainty bands.


Subject(s)
Bystander Effect , Lung Neoplasms/mortality , Lung Neoplasms/physiopathology , Neoplasms, Radiation-Induced/mortality , Neoplasms, Radiation-Induced/physiopathology , Occupational Exposure/statistics & numerical data , Risk Assessment/methods , Adult , Comorbidity , Computer Simulation , Female , Humans , Male , Models, Biological , Prevalence , Risk Factors , Russia/epidemiology , Smoking/mortality
3.
Radiat Res ; 165(1): 1-8, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16392956

ABSTRACT

The purpose of the present study was to analyze the thyroid cancer incidence risk after the Chernobyl accident and its degree of dependence on time and age. Data were analyzed for 1034 settlements in Ukraine and Belarus, in which more than 10 measurements of the (131)I content in human thyroids had been performed in May/June 1986. Thyroid doses due to the Chernobyl accident were assessed for the birth years 1968-1985 and related to thyroid cancers that were surgically removed during the period 1990-2001. The central estimate for the linear coefficient of the EAR dose response was 2.66 (95% CI: 2.19; 3.13) cases per 10(4) PY-Gy; for the quadratic coefficient, it was -0.145 (95% CI: -0.171; -0.119) cases per 10(4) PY-Gy(2). The EAR was found to be higher for females than for males by a factor of 1.4. It decreased with age at exposure and increased with age attained. The central estimate for the linear coefficient of the ERR dose response was 18.9 (95% CI: 11.1; 26.7) Gy(-1); for the quadratic coefficient, it was -1.03 (95% CI: -1.46; -0.60) Gy(-2). The ERR was found to be smaller for females than for males by a factor of 3.8 and decreased strongly with age at exposure. Both EAR and ERR were higher in the Belarusian settlements than in the Ukrainian settlements. In contrast to ERR, EAR increases with time after exposure. At the end of the observation period, excess risk estimates were found to be close to those observed in a major pooled analysis of seven studies of childhood thyroid cancer after external exposures.


Subject(s)
Air Pollutants, Radioactive/toxicity , Chernobyl Nuclear Accident , Environmental Exposure/analysis , Neoplasms, Radiation-Induced/epidemiology , Thyroid Neoplasms/epidemiology , Adolescent , Adult , Age Distribution , Aged , Aged, 80 and over , Body Burden , Child , Child, Preschool , Cohort Studies , Dose-Response Relationship, Radiation , Female , Humans , Incidence , Infant , Infant, Newborn , Male , Middle Aged , Power Plants , Prevalence , Radiation Dosage , Radiation Monitoring/methods , Radioactive Hazard Release , Registries , Republic of Belarus/epidemiology , Retrospective Studies , Risk Assessment/methods , Risk Factors , Sex Distribution , Time Factors , Ukraine/epidemiology
4.
J Environ Radioact ; 85(2-3): 344-60, 2006.
Article in English | MEDLINE | ID: mdl-16125288

ABSTRACT

Models for inhabited areas are used in a variety of applications for accidental or continuous releases of radioactivity to atmosphere. Pathways of interest are external exposure from radioactive material in the cloud or deposited on indoor and outdoor surfaces and people, inhalation from the plume and from material resuspended from the ground. In developing a model for inhabited areas it is necessary to consider what the end users may need and ensure that the model is appropriate for the application; different levels of detail may be appropriate for different applications. This paper considers the main processes governing exposure in inhabited areas, commenting on the extent to which we understand them and how well current models reflect this understanding. It also identifies where the authors believe future modelling is needed and the key areas where the current inhabited area models could be improved.


Subject(s)
Environmental Exposure/analysis , Models, Theoretical , Radioactive Fallout , Air Pollution, Indoor/analysis , Construction Materials , Decontamination , Europe , Housing , Humans , Poaceae , Radiation Dosage , Radioactive Pollutants , Trees
5.
Radiat Environ Biophys ; 44(2): 119-29, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16136318

ABSTRACT

Lung cancer mortality among 5,058 male workers of the Mayak Production Association has been analyzed with emphasis on the interaction of smoking and radiation exposure by using the two-step clonal expansion (TSCE) model of carcinogenesis. The cohort consists of all Mayak workers with known smoking status, who were employed in the period 1948-1972, and who either had the plutonium concentration in urine measured or who worked in the reactors, where plutonium exposure was negligible. Those who died during the first two years after the first urine sampling were excluded. The follow-up extended until the end of 1998. During this time, 2,176 workers died, including 244 lung cancer cases. Mayak workers were exposed to external (gamma and neutron) radiation, and in the radiochemical and plutonium plants to plutonium. In the preferred TSCE model, internal radiation and smoking act on the clonal expansion of pre-carcinogenic clones. Assuming a plutonium radiation weighting factor of 20, the excess relative risk per lung dose was estimated to be 0.11 (95% CI: 0.08; 0.17) Sv(-1). Most of the lung cancer deaths are found to be due to smoking. The second main factor is the interaction of smoking and internal radiation. The model is sub-multiplicative in relative risks due to smoking and radiation. In a multiplicative version of the TSCE model, internal radiation acts on initiation and transformation rates. This model version agrees with conventional epidemiological risk models, because it also suggests a higher risk estimate than the preferred TSCE model. However, it fits the data less well than the preferred model.


Subject(s)
Lung Neoplasms/etiology , Occupational Diseases/etiology , Plutonium/adverse effects , Smoking/adverse effects , Biophysical Phenomena , Biophysics , Cocarcinogenesis , Cohort Studies , Humans , Japan/epidemiology , Likelihood Functions , Lung Neoplasms/mortality , Male , Models, Biological , Models, Statistical , Nuclear Reactors , Nuclear Warfare , Occupational Exposure , Plutonium/administration & dosage , Russia/epidemiology
6.
Health Phys ; 89(3): 233-46, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16096499

ABSTRACT

The cumulative absorbed dose in fired-clay bricks collected from ten buildings in the populated contaminated settlement (137Cs, 1,470 kBq m(-2)) of Stary Vishkov, located 175 km downwind of the Chernobyl Nuclear Power Plant (NPP) in the Bryansk administrative region of Russia, was determined using luminescence techniques by five laboratories. At each location, the cumulative dose, after subtraction of the natural background dose, was translated to absorbed dose in air using conversion factors derived from Monte Carlo simulations. The simulations employed source distributions inferred from contemporary soil contamination data and also took into account heterogeneity of fallout deposition. At four locations the cumulative dose at a reference location was calculated, enabling the luminescence determinations to be compared directly with values of cumulative absorbed dose in air obtained using deterministic models. A "local" conversion factor was also derived from the Monte Carlo simulations for locations where the disturbance of soil was significant. Values of the "local" cumulative dose in air calculated using this factor were compared with those predicted using the deterministic models at each sampled location, allowing location factors to be calculated. The methodology developed is generally applicable to populated areas contaminated by radioactive fallout in which brick buildings are found. The sensitivity of the luminescence techniques for bricks from this region of Russia was sufficient to evaluate cumulative absorbed dose in brick due to fallout of less than 20 mGy.


Subject(s)
Air Pollutants, Radioactive/adverse effects , Chernobyl Nuclear Accident , Construction Materials , Radioactive Fallout , Cesium Radioisotopes/analysis , Environmental Monitoring , Power Plants , Radiation Dosage , Retrospective Studies , Thermoluminescent Dosimetry/methods
7.
Health Phys ; 86(1): 25-41, 2004 Jan.
Article in English | MEDLINE | ID: mdl-14695006

ABSTRACT

The cumulative absorbed dose in bricks collected from six buildings in two heavily contaminated settlements (137Cs > 2,000 kBq m(-2)) located downwind of the Chernobyl Nuclear Power Plant was determined using luminescence techniques by six laboratories. The settlements, Vesnianoje in Ukraine and Zaborie in Russia, are located in, respectively, proximal and distal locations relative to the Chernobyl Nuclear Power Plant. The luminescence determinations of cumulative dose in brick, after subtraction of the natural background dose, were translated to absorbed dose in air at a Reference Location using conversion factors derived from Monte Carlo simulations of photon transport. The simulations employed source distributions inferred from contemporary soil contamination data and also took into account heterogeneity of fallout deposition. This translation enables the luminescence determinations to be compared directly with values of cumulative absorbed dose obtained by computational modeling and also other dose reconstruction methods. For each sampled location the cumulative dose was calculated using three deterministic models, two of which are based on the attenuation of dose-rate with migration of radionuclides in soil and the third on historic instrumental gamma dose-rate data. The results of the comparison of the two methods indicate overall agreement within margins of +/-25%. The methodology developed is generally applicable and adaptable to areas contaminated by much lower levels of radioactive fallout in which brick buildings are found.


Subject(s)
Construction Materials/analysis , Models, Theoretical , Power Plants , Radioactive Fallout/analysis , Radioactive Hazard Release , Radioisotopes/analysis , Radiometry/instrumentation , Radiometry/methods , Computer Simulation , Environmental Monitoring/instrumentation , Environmental Monitoring/methods , Humans , Radiation Dosage , Retrospective Studies , Rural Population , Thermoluminescent Dosimetry/methods , Ukraine , Wind
8.
Radiat Environ Biophys ; 42(3): 169-74, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14579133

ABSTRACT

Absorbed doses were determined by thermoluminescence (TL) measurements for bricks from a height of 6 m from the south-western wall of the former mill in Metlino that faced the Techa river. Measurements of the internal beta-radiation and alpha-radiation in the brick samples and of radionuclide activities in soil samples from the Techa river valley were performed. The absorbed dose in bricks due to the natural radiation was derived and subtracted from the total dose in order to obtain the absorbed dose in the bricks caused by anthropogenic sources. The results were combined with results from two previous studies. The absorbed dose in the bricks due to the radiation field after relocation of the Metlino population in 1956 was derived from dose rates in air measured in front of the sampling locations in 1996/1997. Based on these dose rates the dose to bricks was calculated by means of conversion factors from the literature. The absorbed dose accumulated in the bricks in the period 1949-1956 was nearly 80% of the total dose that had been determined by TL measurements. Previously derived conversion factors were applied to obtain an estimate of the gamma dose in air at the former shore of the Techa river. An uncertainty and sensitivity analysis was performed with the program package Crystal Ball. Care was taken to treat statistical and systematic uncertainties separately and to take parameter correlations into account. The resulting distribution for the gamma dose accumulated in the period 1949-1956 at the Techa river shore has a median value of 32 Gy with a 95% confidence interval of 21-45 Gy. This study confirms the corresponding value of 26.6 Gy that is used in the Techa River Dosimetry System (TRDS) 2000.


Subject(s)
Air Pollutants, Radioactive/analysis , Construction Materials/analysis , Models, Theoretical , Radioactive Waste/analysis , Radioisotopes/analysis , Rivers/chemistry , Thermoluminescent Dosimetry/methods , Water Pollutants, Radioactive/analysis , Adsorption , Air Pollutants, Radioactive/chemistry , Algorithms , Computer Simulation , Environmental Monitoring/methods , Geologic Sediments/analysis , Geologic Sediments/chemistry , Power Plants , Radiation Dosage , Radioisotopes/chemistry , Reproducibility of Results , Risk Assessment/methods , Russia , Sensitivity and Specificity
9.
Radiat Environ Biophys ; 42(1): 17-26, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12687379

ABSTRACT

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.


Subject(s)
Environmental Exposure/analysis , Radiometry/methods , Rivers/chemistry , Water Pollutants, Radioactive/analysis , Beta Particles , Construction Materials , Gamma Rays , History, 20th Century , Luminescent Measurements , Monte Carlo Method , Nuclear Fission , Risk Assessment , Russia , Time Factors , Water Pollutants, Radioactive/history
10.
Radiat Prot Dosimetry ; 101(1-4): 549-52, 2002.
Article in English | MEDLINE | ID: mdl-12382809

ABSTRACT

The use of electron paramagnetic resonance (EPR) tooth dosimetry for calculation of organ doses requires conversion of the measured absorbed dose in enamel. Before deriving conversion factors from simulation calculations with a realistic anthropomorphic human phantom, in the current study a simplified phantom was chosen to compare EPR measurement and Monte Carlo calculation. The dose response of tooth enamel of molars at various positions inside a cylindrical Plexiglas phantom of head-size was calculated hy Monte Carlo modelling in parallel photon beams of X rays of 63 keV equivalent energy and 60Co gamma rays (1.25 Mev). For X ray exposure, preliminary results of EPR dosimetry with tooth enamel samples prepared from molars irradiated in the phantom were in agreement with calculation. The mean value of the ratio of the measured to the calculated dose was 0.93 +/- 0.08.


Subject(s)
Dental Enamel/radiation effects , Photons , Adult , Humans , Molar/radiation effects , Monte Carlo Method , Phantoms, Imaging , Polymethyl Methacrylate , Reproducibility of Results , X-Rays
11.
Radiat Prot Dosimetry ; 99(1-4): 203-6, 2002.
Article in English | MEDLINE | ID: mdl-12194284

ABSTRACT

To test possible effects of the heterogeneous nature of the cell nucleus on simulation results of radiation-induced DNA damage, inhomogeneous targets have been implemented in the biophysical code PARTRAC. The geometry of the DNA and the histones was defined by spheres around the constituent atoms. Electron cross sections in liquid water were scaled according to the mass density of the different materials, whereas photon cross sections were derived from the sum of the cross sections for the constituent atoms. In the case of higher energy electrons the simulations show an increase of energy deposition in the DNA proportional to its high mass density. For photons with energies in the range of the carbon and the oxygen K-shell (0.28-0.53 keV), cross sections of DNA are larger than those of water, leading to an increased yield of strand breaks per average absorbed dose in the cell nucleus.


Subject(s)
DNA Damage/radiation effects , DNA/radiation effects , Linear Energy Transfer , Computer Simulation , DNA/genetics , Dose-Response Relationship, Radiation , Monte Carlo Method
12.
Health Phys ; 82(1): 94-101, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11768803

ABSTRACT

Bricks collected from a contaminated village (Muslyumovo) of the lower Techa river valley, Southern Urals, Russia, were measured using thermoluminescence and optically stimulated luminescence by four European laboratories and a U.S. laboratory to establish and compare the applied dose reconstruction methodologies. The bricks, collected from 60-100-year-old buildings, had accumulated a relatively high dose due to natural sources of radiation in the brick and from the surrounding environment. This work represents the results of a first international intercomparison of luminescence measurements for bricks from the Southern Urals. The luminescence measurements of absorbed dose in bricks collected from the most shielded locations of the same buildings were used to determine the background dose due to natural sources of radiation and to validate the age of the bricks. The absorbed dose in different bricks measured by four laboratories using thermoluminescence and optically stimulated luminescence at a depth of 10 +/- 2.5 mm from the exposed brick surface agreed within +/-21%. After subtraction of the natural background dose, the absorbed dose in brick due to contaminated river sediments and banks was calculated and found to range between 150 and 200 mGy. The cumulative doses in brick due to man-made sources of radiation at 100 and 130 mm depths in the bricks were also measured and found to be consistent with depth dose profiles calculated by Monte Carlo simulations of photon transport for possible source distributions.


Subject(s)
Luminescent Measurements , Radioactive Pollutants/analysis , Radiometry , Background Radiation , Radiation Protection , Russia
13.
Appl Radiat Isot ; 54(5): 793-9, 2001 May.
Article in English | MEDLINE | ID: mdl-11258529

ABSTRACT

The EPR dose response of tooth enamel was determined for human molars collected in Egypt. The influence of age, gender and residence of the tooth donors as well as tooth position and sample preparation on EPR sensitivity and its variability over the enamel samples was investigated. The EPR sensitivity and its variability were found to depend only on the sample preparation procedure. The variability in EPR sensitivity of enamel from Egyptian teeth was maximally 10% and the mean sensitivity was in good agreement with that of German teeth.


Subject(s)
Dental Enamel/radiation effects , Electron Spin Resonance Spectroscopy , Age Factors , Egypt , Female , Germany , Humans , Male , Molar , Radiation Dosage , Reproducibility of Results , Sensitivity and Specificity , Sex Factors
14.
Health Phys ; 75(6): 574-83, 1998 Dec.
Article in English | MEDLINE | ID: mdl-9827504

ABSTRACT

The potential of thermoluminescence measurements of bricks from the contaminated area of the Techa river valley, Southern Urals, Russia, for reconstructing external exposures of affected population groups has been studied. Thermoluminescence dating of background samples was used to evaluate the age of old buildings available on the river banks. The anthropogenic gamma dose accrued in exposed samples is determined by subtracting the natural radiation background dose for the corresponding age from the accumulated dose measured by thermoluminescence. For a site in the upper Techa river region, where the levels of external exposures were extremely high, the depth-dose distribution in bricks and the dependence of accidental dose on the height of the sampling position were determined. For the same site, Monte Carlo simulations of radiation transport were performed for different source configurations corresponding to the situation before and after the construction of a reservoir on the river and evacuation of the population in 1956. A comparison of the results provides an understanding of the features of the measured depth-dose distributions and height dependencies in terms of the source configurations and shows that bricks from the higher sampling positions are likely to have accrued a larger fraction of anthropogenic dose from the time before the construction of the reservoir. The applicability of the thermoluminescent dosimetry method to environmental dose reconstruction in the middle Techa region, where the external exposure was relatively low, was also investigated.


Subject(s)
Computer Simulation , Environmental Pollution/analysis , Radioactive Hazard Release , Water Pollution, Radioactive/analysis , Water Supply , Alpha Particles , Beta Particles , Construction Materials , Fresh Water , Hot Temperature , Humans , Luminescent Measurements , Monte Carlo Method , Radiation, Ionizing , Russia , Strontium/analysis
15.
Appl Radiat Isot ; 47(4): 433-40, 1996 Apr.
Article in English | MEDLINE | ID: mdl-8624509

ABSTRACT

The analysis of depth-dose distributions in bricks sampled from walls in areas with nuclear waste or accident contamination has the potential of providing information on the energy and source configuration of the gamma-radiation that had been incident on the brick. In this study, a brick from a mill facing a shallow water reservoir of the contaminated Techa river in the South Ural region is investigated. Thermoluminescence (TL) methods were used to measure the accumulated dose at several depths in the brick. The accidental external gamma-dose is obtained by subtracting the natural radiation background dose from the total accumulated dose. In the first segment of the brick, at a depth of about 1.5 cm, the accident dose was found to be roughly 3.5 Gy. Monte-Carlo simulations of the photon transport from the reservoir bed contaminated with 137Cs were calculated for different depths in the brick. The calculations were made assuming different attenuating water levels. It is found that the depth-dose distribution determined by measurements corresponds to a water level between 20 and 50 cm. The results indicate that TL measurements combined with Monte-Carlo modelling calculations are highly promising for external gamma-dose reconstruction applications.


Subject(s)
Construction Materials , Radioactive Fallout/analysis , Beta Particles , Gamma Rays , Radioactive Hazard Release , Radioactive Waste , Temperature , Ukraine
16.
Radiat Environ Biophys ; 33(3): 251-67, 1994.
Article in English | MEDLINE | ID: mdl-7809371

ABSTRACT

Since the reactor accident of Chernobyl, cesium depth profiles and nuclide-specific kerma rates in air have been determined for various grassland sites in south Bavaria and in Ukraine. The sites are described by soil characteristics, annual precipitation, distance from release point, mode of deposition, and activity per unit area. The effects of surface roughness and migration of cesium into the soil on the kerma rate in air over grasslands was determined by two methods. The kerma rates in air obtained by the evaluations of in situ gamma-ray spectrometry results and of measured activity distributions in the soil showed only negligible differences for the observation period of 6 years after deposition. For the sites in Ukraine the kerma rate in air per activity per unit area was found to be systematically 40% higher than in Bavaria. The results from Bavaria on the attenuation of the kerma rate and a data set, including experiences from the weapons test fallout, are analytically approximated as a function of time up to 25 years after deposition.


Subject(s)
Air Pollutants, Radioactive/analysis , Cesium Radioisotopes/analysis , Soil Pollutants, Radioactive/analysis , Gamma Rays , Russia , Ukraine
17.
Health Phys ; 62(6): 519-28, 1992 Jun.
Article in English | MEDLINE | ID: mdl-1628983

ABSTRACT

When applying the standard method of in-situ gamma spectrometry to determine deposited radionuclide activities, an assumption is needed regarding the depth distribution of radionuclides in the ground. The method can be improved by assessing, from information contained in the spectrum, the attenuation of the radiation by the soil and vegetation. By comparing the count rates of the x ray and the gamma-ray lines of its daughter nuclide 137mBa, the 137Cs activity per area can be determined. The range of applicability of the method is discussed by means of an uncertainty analysis, and the method is applied to post-Chernobyl measurements. A comparison with the results of the standard method of in-situ spectrometry demonstrates the progress achieved by the proposed method. Nevertheless, the method still has some shortcomings for the peak analysis that could be improved by better detector resolution or better computer software.


Subject(s)
Cesium Radioisotopes , Radioactive Fallout/analysis , Soil Pollutants, Radioactive/analysis , Spectrometry, Gamma/methods , Models, Theoretical , Radioactivity
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