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PubMed2006

High-resolution alpha spectrometry under field conditions - fast identification of alpha particle emitting radionuclides from air samples.

Alpha particle emitting radionuclides may be released into the atmosphere as a result of a severe nuclear accident, the malevolent use of radioactive material or some other incident. Rapid detection methods are then of crucial importance for carrying out well-timed protective actions. The present paper demonstrates that a method in which an aerosol sample is collected on a filter and directly analysed by high-resolution alpha spectrometry in a vacuum chamber, but without radiochemical sample treatment, is suitable for field measurements. A detection limit of less than 0.1 Bqm(-3) for (239)Pu is achieved assuming 1-h sampling using a glass-fibre filter and 1-h data acquisition. This value is higher than in the case when sampling is performed using a porous membrane filter. A measurement system consisting of standard components is mounted in a vehicle designed for rapid field measurements.

Air Pollutants, Radioactive↗
PubMed2006

Long-term monitoring of radioactivity in surface air and deposition in New York State.

Gross-beta activities have been determined weekly for 22 y from filtered atmospheric aerosols at seven sites in New York State. The activities, ranging from 0.1 to 0.9 mBq m(-3), varied seasonally and were evaluated in terms of meteorological factors. Cosmogenic beryllium (7Be) concentrations were determined quarterly on the air filters and weekly in deposition collected at one site. Over 98% of the air filters contained observable activity concentrations of 7Be (mean of 3 mBq m(-3)) and 210Pb (mean of 1 mBq m(-3)). However, only 20% of deposition samples contained Be concentrations above analytical detection limits. Tritium (3H) concentrations were below detection limits in deposition samples at the background site, but were present on most samples collected near a H-processing facility. Measurements of 131I were conducted weekly on charcoal canisters, with only one site showing observable concentrations (mean of 1 mBq m(-3)), due to nearby incineration of dried municipal sludge containing patient waste from hospital treatments.

Air Pollutants, Radioactive↗
PubMed1996

Outdoor field evaluation of passive tritiated water vapor samplers at Canadian power reactor sites.

Tritium is one of several radioactive nuclides routinely monitored in and around CANDU (CANada Deuterium Uranium) power reactor facilities. Over the last ten years, passive samplers have replaced active sampling devices for sampling tritiated water vapor in the workplace at many CANDU stations. The potential of passive samplers for outdoor monitoring has also been realized. This paper presents the results of a 1-y field trial carried out at all five Canadian CANDU reactor sites. The results indicate that passive samplers can be used at most sampling locations to measure tritiated water vapor in air concentrations as low as 1 Bq m-3 over a 30-d sampling period. Only in one of the five sampling locations was poor agreement observed between active and passive monitoring data. This location, however, was very windy and it is suspected that the gusty winds were the source of the discrepancies observed.

Air Pollutants, Radioactive↗
PubMed1996

Measurement of airborne 218Po--a Bayesian approach.

The standard mathematical treatment of the buildup and decay of airborne radionuclides on a filter paper uses the solutions of the so-called Bateman equations adapted to the sampling process. These equations can be interpreted as differential equations for the expectation of an underlying stochastic process, which describes the random fluctuations in the accumulation and decay of the sampled radioactive atoms. The process for the buildup and decay of airborne 218Po can be characterized as an "immigration-death process" in the widely adopted, biologically based jargon. The probability distribution for the number of 218Po atoms, accumulated after sampling time t, is Poisson. We show that the distribution of the number of counts, registered by a detector with efficiency epsilon during a counting period T after the end of sampling, is also Poisson, with mean dependent on epsilon, t, T, the flowrate and N(o), the number of airborne 218Po atoms per unit volume. This Poisson distribution was used to construct the likelihood given the observed number of counts. After inversion with Bayes' Theorem we obtained the posterior density for N(o). This density characterizes the remaining uncertainty about the measured number of 218Po atoms per unit volume of air.

Air Pollution, Radioactive↗
PubMed1986

A Monte Carlo program to calculate the exposure rate from airborne radioactive gases inside a nuclear reactor containment building.

A program was developed to calculate the exposure rate resulting from airborne gases inside a reactor containment building. The calculations were performed at the location of a wall-mounted area radiation monitor. The program uses Monte Carlo techniques and accounts for both the direct and scattered components of the radiation field at the detector. The scattered component was found to contribute about 30% of the total exposure rate at 50 keV and dropped to about 7% at 2000 keV. The results of the calculations were normalized to unit activity per unit volume of air in the containment. This allows the exposure rate readings of the area monitor to be used to estimate the airborne activity in containment in the early phases of an accident. Such estimates, coupled with containment leak rates, provide a method to obtain a release rate for use in offsite dose projection calculations.

Accidents↗
PubMed2006

Modeling a potential atmospheric release from a waste disposal facility at the savannah river site as an area source.

The Saltstone Facility was designed at the Savannah River Site (SRS) to treat and dispose of certain low-level liquid radioactive wastes. The final product of Saltstone is several large concrete vaults. As part of the performance assessment for Saltstone, reduction of dose to receptors downwind of the vaults have been estimated for treating the vaults as an area atmospheric source as opposed to a point source. The CAP88 model has the ability to handle area sources, but the methods are not appropriate for receptors close to the source such as those modeled at 100 m. Use of the area source as opposed to the point source can reduce the dose by as much as a factor of 5 depending on vault size. A method for quickly assessing the dose from an area source for near-in exposures is demonstrated here.

Air Movements↗
PubMed2002

[Radiation effects of the Chernobyl accident on the Hungarian population].

Due to the nuclear accident at Chernobyl in April 1986, the atmospheric transport spread the released radioactivity throughout the whole Europe. The initial plume moved into the north-western direction and a portion of this plum turned to west and later on to south-west. The central European countries including Hungary became affected in 29-30 April. The release during the last period (5-7 May) was directed to Romania, Bulgaria and Greece. In addition to the main trajectories of the atmospheric transport, the local meteorological conditions with winds of different directions at various altitudes, rainfalls etc. produced a very complex deposition pattern in Central Europe. The contamination of the soil surface and vegetation were strongly influenced by the wash-out of the radioactive materials from the local air. Due to the high geographical variation of the rains the surface contamination provided a similar heterogeneity among the territories of the country. The northern-west part and the region of the capital Budapest became nearly 5 times higher contaminated than the middle part of the country. Radiation doses of the population have been provided by activity concentrations in air, soil, vegetation, foods etc. and the external dose rates, mainly due to the surface contamination by the isotopes of 131I, 134Cs and 137Cs. The average effective dose contribution received by the individuals (adults) in Hungary during the 15 years following the accident has been assessed to be 0.30 mSv while the annual dose from the natural background is 2.5-3 mSv. Contribution to total dose from the internal pathway (committed effective dose) resulted about 0.10 mSv and the external radiation provided 0.19 mSv. The contributions of the external exposure from the contaminated air and inhalation are less than 5% of the total one.

Air Pollutants, Radioactive↗
PubMed2003

Database of calculated values of retention and excretion for members of the public following acute intake of radionuclides.

Intakes of radionuclides can be estimated from measurements of radioactivity in the whole body or in specific organs or in excreta by comparing them with predicted retention or excretion data calculated using standard biokinetic models. For occupational exposure monitoring, data are presented by ICRP for 29 radionuclides in Publication 78 (1997) and by the authors for 42 radionuclides as electronic look-up tables in Microsoft Excel. In the present work, values of retention and excretion were computed for selected radionuclides inhaled or ingested by members of the public. Graphs were constructed from the computed results showing the predicted monitoring data as functions of time following acute intakes of radionuclides. A graphical database was assembled on the Web site http//www.nirs.go.jp/RPD/ to provide a tool for the interpretation of bioassay measurements.

Administration, Inhalation↗
PubMed1996

Identification and screening evaluation of key historical materials and emission sources at the Oak Ridge Reservation.

In 1991, the State of Tennessee initiated a Health Studies Agreement with the U.S. Department of Energy. It included independent studies of possible adverse health effects in people living near the Oak Ridge Reservation resulting from releases of chemicals and radionuclides since 1942. A Dose Reconstruction Feasibility, the first of a planned sequence of initiatives to evaluate the potential for health effects, included application of screening methods to focus subsequent dose reconstruction and epidemiologic efforts on the materials and emission sources that have historically been most important. The feasibility study produced a history of operations that likely generated off-site releases from the X-10, K-25, Y-12, and S-50 plants, based on reviews of classified and unclassified records and interviews of active and retired workers. The availability of environmental monitoring and research data that would support dose reconstruction was also characterized. Quantitative emission and environmental contamination data were used to identify those materials and plant activities that should receive the highest priority in further health studies. Plausible exposure pathways were identified, and screening methods were used to identify the most important pathways and past activities that appear to be associated with the greatest health hazards. The materials and activities shown to have the highest potential for public health hazards are as follows: 1) The release of radioiodine [likely over 3.7 PBq (100,000 Ci)] to the air from radioactive lanthanum ("RaLa") processing at X-10 (now Oak Ridge National Laboratory) from 1944 through 1956; 2) The release of 137Cs and other radionuclides in liquid wastes from chemical separation activities at X-10; 3) The release of mercury to the air, soil, and surface waters from Y-12 lithium enrichment operations between 1950 and 1963. About 11,000,000 kg of mercury were handled at Y-12, and 910,000 kg were reported lost or unaccounted for; and 4) The release of polychlorinated biphenyls (PCBs) from machining oils, electrical equipment, and other sources in the Oak Ridge area. Based on the findings of the study, the Oak Ridge Health Agreement Steering Panel called for a dose reconstruction for radioiodine, mercury, PCBs, and radionuclides released from White Oak Creek and research into opportunities for analytic epidemiologic studies to identify adverse health effects in exposed populations.

Air Pollutants, Radioactive↗
PubMed1984

Ambient monitoring of airborne radioactivity near a former thorium processing plant.

Twenty-four hour sampling for airborne radioactivity near a former thorium and rare-earth extraction facility was conducted for approx. 2 months with high-volume and dichotomous air samplers. Thoron ( 220Rn ) daughters were identified in the air and confirmed to be originating from the waste storage site. High-volume samplers near the facility measured average 212Pb concentrations of 177, 43, and 237 pCi/m3 with corresponding ranges of (1.9-1351), (1.5-301) and (0.73-2201)pCi/m3. Simultaneous measurements with dichotomous samplers at the same sites measured average 212Pb concentrations on coarse particulates (2.5-15 microns dia.) of 14, 4 and 10 pCi/m3 and on fine particulates (less than 2.5 microns dia.) of 94, 9 and 214 pCi/m3, respectively. Corresponding ranges were (0.2-109), (0.1-63) and (0.1-94) pCi/m3 for coarse particulates and (0.7-1094), (0.4-101) and (0.5-2685) pCi/m3 for fine particulates. Uranium, thorium and radium radionuclides were not identified as being present in significant concentrations in the particulate samples.

Air Pollutants↗
PubMed2004

Development and management of a radon assessment strategy suitable for underground railway tunnelling projects.

The construction of underground tunnels through radon-bearing rock poses a radiation health risk to tunnelling workers from exposure to radon gas and its radioactive decay products. This paper presents the development and practical application of a radon assessment strategy suitable for the measurement of radon in tunnelling work environments in Hong Kong. The assessment strategy was successfully evaluated on a number of underground railway tunnelling projects over a 3 y period. Radon measurements were undertaken using a combination of portable radon measurement equipment and track etch detectors (TEDs) deployed throughout the tunnels. The radon gas monitoring results were used to confirm that ventilation rates were adequate or identified, at an early stage, when further action to reduce radon levels was required. Exposure dose estimates based on the TED results showed that the exposure of tunnel workers to radon did not exceed 3 mSv per annum for the duration of each project.

Air Pollutants, Radioactive↗
PubMed1999

Chromosome breakage at sites of oncogenes in a population accidentally exposed to radioactive chemical pollution.

The purpose of the present study was to investigate the level of aberrations at fragile sites of chromosomes in peripheral blood lymphocytes of the population of an area polluted with radionuclides, following an accident at the Siberian Chemical Plant. We carried out the micronucleus test to screen people with radiation-related cytogenetic effects. Of the 1246 inhabitants of the settlement of Samus examined, 148 showed a significantly increased frequency of micronucleated erythrocytes and were selected for chromosome analysis as a radiation-exposed group. Additional analysis was carried out on 40 patients with gastric cancer and atrophic gastritis with stage II-III epithelial dysplasia. Eighty six individuals from a non-polluted area were used as a control group. Chromosomal breaks and exchanges occurred preferentially in chromosomes 3 and 6 among radiation-exposed persons and patients. The regions 3p14-25 and 6p23 were damaged most often. There was a tendency to preferential involvement of q21-25 of chromosome 6 in patients with gastric cancer and atrophic gastritis. Specific damage at certain chromosome sites was observed in the radiation-exposed population as well as in patients with gastric cancer. Most often this damage was located near oncogene loci, which could imply that chromosome damage induced by radiation is likely to be a predisposing factor to the expression of oncogenes and malignant transformation of cells in exposed individuals.

Adult↗
PubMed2000

Pneumotoxic effects of radioactive dust (RD) from a nuclear power plant in Kozloduy, Bulgaria.

BACKGROUND: Airborne radioactive particles isolated from the reactor halls of nuclear power plants are a potential risk to the respiratory system of the working staff. Such radioactive dust (RD) from the Nuclear Power Plant, Kozloduy, Bulgaria was investigated. METHODS: The RD was administered intratracheally to 60 male Wistar rats as an aqueous suspension and the biological effects are estimated, using sensitive biological markers in bronchoalveolar lavage fluid (BALF) and important parameters of the pulmonary antioxidant defense. RESULTS: The results obtained show that RD increases the total cell number, the activities of the lactate dehydrogenase and alkaline phosphatase as well as the protein content in BALF. The activities of superoxide dismutase and catalase in lung homogenate are decreased while activity of the glutathione peroxidase and the content of non-protein sulfhydrils is elevated. CONCLUSIONS: It is concluded that the RD causes transitory toxic effect on lung tissue and changes the correlation between the elements of the pulmonary antioxidative defense.

Air Pollutants, Radioactive↗
PubMed1996

The whole-body incorporation of radioactive caesium in Switzerland during the last 30 years: a survey of young persons in Geneva and some measurements of Belarusian and Ukrainian children.

In a cross-sectional study, at least 40 young men and women about 18 years old (half of each sex) were selected each year, and the body concentration of 137Cs was measured in a whole-body counter. This radioisotope, with a half-life of 30 years, originates from the atom bomb explosions in the atmosphere, which were stopped in 1963, or from the accident at Chernobyl. The concentrations due to the emissions from this reactor remained below one-third of the values due to atomic bombs. The results in children from Belarus who spent a few weeks in Switzerland in the summer are lower than would have been expected according to the literature from Russia, but correspond to those recently obtained in situ by international scientific teams.

Adolescent↗
PubMedDate not supplied

Adult leukemia and proximity-based surrogates for exposure to Pilgrim plant's nuclear emissions.

Possible associations between adult leukemia incidence and proximity-based surrogate measures of potential for exposure to radioactive emissions from the Pilgrim nuclear power plant in Plymouth, Massachusetts, were investigated. Included in this study were 105 nonchronic lymphocytic leukemia cases, diagnosed between 1978 and 1986 at age 13 y or older, that occurred in 22 towns near Pilgrim; population controls numbered 208. Residence within 4 mi (6.4 km) of Pilgrim during "high-emissions" years was related to case-control status (adjusted odds ratio [OR] = 3.88, 95% confidence interval [95% CI] = 0.81-10.64). A high "exposure" score (i.e., a value that accounted for downwind time) was also related to case-control status (OR = 3.46, 95% CI = 1.50-7.96). Some statistically significant dose-response trends were found. Cautious interpretation of associations is warranted in light of the low levels of reported emissions.

Adolescent↗
PubMed2006

The second EURADOS intercomparison of national network systems used to provide early warning of a nuclear accident.

In 1999 and 2002, the EURADOS Working Group on Environmental Monitoring organised two European intercomparison exercises of national network systems used to provide early warning in case of a nuclear accident. In total, 12 European countries, represented by more than 40 scientists, participated in these two intercomparisons with more than 35 different dose rate detectors. In addition, an in situ gamma spectrometry intercomparison was performed by a group of European scientists during the 2002 exercise. Results of these spectrometry measurements will be reported elsewhere. This report summarises the results of the second intercomparison, performed in 2002, at the environmental dosimetry facilities of the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The unique combination of the ultra-low background Underground Laboratory (UDO) and two free-field sites (a floating platform on a lake showing an almost pure cosmic radiation field and a free-field gamma ray irradiation facility) provide the particular opportunity to precisely quantify the inherent background of the detectors and to calibrate them almost free of any background and traceable to PTB's primary standards. In addition, the intercomparison comprised investigations on the energy and dose rate dependence of the detectors' response to gamma radiation as well as on the response to cosmic radiation. Finally, the sensitivity of the detector systems to small dose rate variations, similar to that caused by a passing overhead radioactive plume, was studied under realistic free-field conditions. Following the Council Directive 96/29/EURATOM, the participants of the 2002 intercomparison were asked to report their results in terms of the operational quantity ambient dose equivalent, H(*)(10). Although the verification of the individual calibrations showed smaller discrepancies than those in the 1999 intercomparison, in a few cases, these discrepancies would be still unacceptably high in the case of a real emergency situation as demonstrated by the plume results. This shows the clear need for further efforts towards a European harmonisation in environmental dosimetry. For this purpose, a further intercomparison shall be held at the PTB in 2006, especially with the participation of new members of the European Union.

Air Pollution, Radioactive↗
PubMed1994

Airborne radioactive contamination following aerosol ventilation studies.

Lung aerosol ventilation studies may be accompanied by airborne contamination, with subsequent surface contamination. Airborne contamination has been measured prior to, during and following 59 consecutive 99Tcm-diethylenetriamine pentaacetate (DTPA) aerosol studies using a personal air sampler. Airborne contamination ranging between 0 and 20 330 kBq m-3 has been measured. Airborne contamination increases with degree of patient breathing difficulty. The effective dose equivalent (EDE) to staff from ingested activity has been calculated to be 0.3 microSv per study. This figure is supported by data from gamma camera images of a contaminated staff member. However, surface contamination measurements reveal that 60% of studies exceed maximum permissible contamination limits for the hands; 16% of studies exceed limits for controlled area surfaces. The EDE from ingestion is low, but protective clothing is essential to prevent body and clothing contamination. Ingested activity and surface contamination results from this study have been compared with results from a Technegas study.

Aerosols↗
PubMed1984

Ingestion pathway factor in dose assessment for annual airborne releases of radioactivity.

An analytic model is derived for use in a simplified assessment of the committed effective dose equivalent to the public due to routine airborne releases of radioactive materials. The model uses the dosimetry in ICRP Publication 30 and determines the ratio of the committed effective dose equivalent (CEDE) via a specified ingestion pathway relative to that CEDE by inhalation per annual airborne release of a radionuclide. This ratio is defined as the ingestion pathway factor (IPF) and is shown to depend upon the radionuclide annual limits of intake, the atmospheric deposition velocity, and an ingestion parameter, the effective contamination intake area. The IPF values are tabulated for several radionuclides. These resultant IPF values often exceed unity, suggesting that the ingestion path is often the critical or limiting pathway for off-site CEDE to an individual. An application of this assessment is demonstrated in a review of a hypothetical nuclear facility to determine the appropriate extent of radiologic effluent and environmental monitoring at the facility.

Air Pollutants↗