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PubMed1997

Plutonium in fish, algae, and sediments in the Barents, Petshora and Kara Seas.

This work contributed to a joint research programme between the Finnish Centre for Radiation and Nuclear Safety and the Murmansk Marine Biological Institute in the Arctic. Radioanalyses for plutonium isotopes were performed on more than 50 sediment samples, 12 algae samples and 19 fish samples. Plutonium concentrations in algae and fish samples, including fish meat, bone and liver, were low or in many cases below detection limits. Some differences in plutonium concentrations of sediments were found between different sampling areas. However, the concentrations were low. The Pu isotopic ratios were similar to those found in environmental samples generally when Pu is derived from global fallout or discharges from reprocessing plants. No local enhancement of plutonium contamination was found in the marine areas studied. However, the sampling locations represent only areas of free access; prohibited military areas of North-west Russia with potential pollution sources were not included.

Animals↗
PubMedDate not supplied

A method to determine the time since last purification of weapons grade plutonium.

A non-destructive technique to determine the time since last purification of weapons grade plutonium based on the 241Pu decay series has been developed and demonstrated to provide results that are consistent with our historical and process knowledge. This method is based on the use of the Bateman equations and the decay chain 241Pu-->237U & 241Am-->237Np-->233Pa. Secular equilibrium is assumed between the (2.1 x 10(6) year) 237Np and the (27 day) 233Pa. The proposed method is dependent upon the efficiency of the plutonium separation process but makes no assumption about the relative abundance of 241Pu in 239Pu. Even though the technique was developed for weapons grade plutonium, it is expected to apply to almost any material that contains plutonium.

Algorithms↗
PubMed2003

Work and disproportionation for aqueous plutonium.

The relation of two plutonium work integrals has recently been illustrated. One of the integrals applies to the work of disproportionation of tetravalent plutonium in 1 M acid and the other to the work of oxidation of plutonium from the trivalent to a higher oxidation state. This paper generalizes the disproportionation work integral so that it can be applied to tetravalent plutonium at any acid concentration. An equation is provided that can be used to verify work estimations obtained by integration. It applies to oxidation and disproportionation processes and it is easy to use.

Computer Simulation↗
PubMed1999

Radiotoxicity of plutonium in NTA-degrading Chelatobacter heintzii cell suspensions.

The radiotoxicity of plutonium in NTA-degrading Chelatobacter heintzii cell suspensions was investigated as part of a more general study to establish the key interactions between actinide-organic complexes and microorganisms in the subsurface. The radiation tolerance of C. heintzii, based on 60Co gamma irradiation experiments, was 165 +/- 30 Gy. No bacteria survived irradiation doses greater than 500 Gy. In the presence of plutonium, where alpha particle decay was the primary source of ionizing radiation, the observed toxicity was predominantly radiolytic rather than chemical. This was evident by the greater effect of activity, rather than concentration, on the toxicity noted. Bioassociation of plutonium with C. heintzii was postulated to be an important and necessary step in the observed loss of cell viability since this was the best way to account for the observed death rate. The radiotoxicity of plutonium towards bacteria is a potentially important consideration in the bioremediation of sites contaminated with radionuclide-organic mixtures and the bioprocessing of nuclear waste.

Gram-Negative Aerobic Bacteria↗
PubMed1986

The gastrointestinal absorption of organically bound forms of plutonium in fed and fasted hamsters.

Values of about 0.005-0.01 per cent were obtained for the absorption in fed hamsters of plutonium ingested as Pu4+ citrate, isocitrate, phytate and malate complexes and Pu3+ ascorbate compared with about 0.003-0.004 per cent for Pu4+ nitrate. Replacing drinking water with tea did not affect the result for Pu4+ nitrate. Fasting hamsters for 8 h before the administration of plutonium citrate increased absorption to 0.1-0.2 per cent. An extra period of fasting for 4 h after administration did not lead to a further increase in absorption. Similar values were also obtained when plutonium citrate was administered after a 24 h fast, followed either by immediate access to food or a further 4 h fast. In hamsters fasted for 24 h before administration of either Pu3+ ascorbate or Pu4+ nitrate, about 6-7 per cent of the ingested plutonium was retained in the gastrointestinal tract after one week. At three weeks after ingestion of Pu3+ ascorbate, gastrointestinal retention had fallen 100-fold without an increase in absorption.

Animals↗
PubMed1979

The gastrointestinal absorption of plutonium and americium in the hamster.

Plutonium-239 and americium-241 were administered to adult hamsters in various chemical forms and their absorption from the gut was measured. The results have been compared with published data on other species in order to derive values for the estimated absorption of these actinides in man. On the basis of current knowledge, the best values for adults would appear to be: 0.05% for americium, 0.01% for plutonium ingested in soluble form, and 0.0001% for plutonium ingested as the dioxide. Plutonium dioxide should be considered as soluble if a significant proportion (greater than 5%) of the activity is in particles less than 25 nm in diameter.

Administration, Oral↗
PubMed1993

Plutonium in south-central Washington State autopsy tissue samples--1970-1975.

Results are presented of postmortem human tissue sampling and analysis for plutonium of Hanford Site workers, residents of the nearby Tri-Cities, and individuals residing farther away from the Hanford Site for the period 1970-1975. The majority of Hanford Site workers and nearby residents coming to autopsy had tissue concentrations of plutonium no larger than those who lived farther away from Hanford and whose likely source of plutonium was limited to nuclear weapons testing fallout. Thus, Hanford operations up to that time apparently had made no significant addition to plutonium in those individuals sampled postmortem.

Autopsy↗
PubMed1994

Soft tissue concentrations of plutonium and americium in occupationally-exposed humans.

Human tissues, obtained at autopsy from 82 volunteer donors with a history of occupational exposure, were analyzed for 238Pu, 239 + 240Pu, and 241Am by chemical separation and subsequent alpha spectrometry. Concentrations of these actinide nuclides in soft tissues (testes, thyroid gland, spleen, kidneys, heart, and skeletal muscle) were compared to those of the livers in the same subjects. Tissue:liver concentration ratios were essentially constant over a wide range of liver concentrations. The spleen had consistently high actinide concentrations relative to liver; however, the heart had the greatest concentration ratio for 241Am. Testes had relatively high concentration ratios of the plutonium nuclides but low concentrations of 241Am. Skeletal muscle had low concentrations of plutonium relative to liver but high concentrations of 241Am. In the tissues studied, concentration ratios of 241Am were greater than those of the plutonium nuclides, most likely a result of more rapid excretion of that nuclide than the plutonium nuclides by the liver.

Americium↗
PubMed1996

Natural radionuclide and plutonium content in Black Sea bottom sediments.

The content of uranium, thorium, radium, lead, polonium, and plutonium in bottom sediments and algae from two locations at the Bulgarian Black Sea coast have been determined. Some parent:progeny ratios for evaluation of the geochemical behavior of the nuclides have been estimated as well. The extractable and total uranium and thorium are determined by two separate radiochemical procedures to differentiate the more soluble chemical forms of the elements and to estimate the potential hazard for the biosphere and for humans. No distinct seasonal variation as well as no significant change in total and extractable uranium (also for 226Ra) content is observed. The same is valid for extractable thorium while the total thorium content in the first two seasons is slightly higher. Our data show that 210Po content is accumulated more in the sediments than 210Pb, and the evaluated disequilibria suggest that the two radionuclides belong to more recent sediment layers deposited in the slime samples compared to the silt ones for the different seasons. The obtained values for plutonium are in the lower limits of the data cited in literature, which is quite clear as there are no plutonium discharge facilities at the Bulgarian Black Sea coast. The obtained values for the activity ratio 238Pu:239 + 240Pu are higher for Bjala sediments compared to those of Kaliakra. The ratio values are out of the variation range for the global contamination with weapon tests fallout plutonium which is probably due to Chernobyl accident contribution. The dependence of natural radionuclide content on the sediment type as well as the variation of nuclide accumulation for two types of algae in two sampling locations for five consecutive seasons is evaluated. No serious contamination with natural radionuclides in the algae is observed.

Eukaryota↗
PubMed1996

Plutonium releases from the 1957 fire at Rocky Flats.

The Colorado Department of Public Health and Environment sponsored a study to reconstruct contaminant doses to the public from the Rocky Flats nuclear weapons plant. This analysis of the September 1957 fire in a plutonium fabrication building that breached the building air filtration system is part of the Colorado Department of Public Health and Environment study. The plutonium release from this fire is estimated using environmental data collected around the time of the fire and an air dispersion model. The approximate upper bound on the total plutonium release from the fire is 1.9 GBq (0.05 Ci), with an uncertainty of about two orders of magnitude. Off-site air concentrations and deposition of plutonium resulting from the approximate upper-bound release are estimated. The highest predicted off-site effective dose resulting from the approximate upper-bound release is about 13 microSv (1.3 mrem).

Air Pollutants, Radioactive↗
PubMed1997

Evaluation of continuous air monitor placement in a plutonium facility.

Department of Energy appraisers found continuous air monitors at Department of Energy plutonium facilities alarmed less than 30% of the time when integrated room plutonium air concentrations exceeded 500 DAC-hours. Without other interventions, this alarm percentage suggests the possibility that workers could be exposed to high airborne concentrations without continuous air monitor alarms. Past research has shown that placement of continuous air monitors is a critical component in rapid and reliable detection of airborne releases. At Los Alamos National Laboratory and many other Department of Energy plutonium facilities, continuous air monitors have been primarily placed at ventilation exhaust points. The purpose of this study was to evaluate and compare the effectiveness of exhaust register placement of workplace continuous air monitors with other sampling locations. Polydisperse oil aerosols were released from multiple locations in two plutonium laboratories at Los Alamos National Laboratory. An array of laser particle counters positioned in the rooms measured time-resolved aerosol dispersion. Results showed alternative placement of air samplers generally resulted in aerosol detection that was faster, often more sensitive, and equally reliable compared with samplers at exhaust registers.

Aerosols↗
PubMed1997

A three-dimensional spatial model of plutonium in soil near Rocky Flats, Colorado.

The horizontal and depth distribution of plutonium was measured in soil east of the Rocky Flats Environmental Technology Site (formerly the Rocky Flats Plant) near Denver, Colorado, during 1992-1994. The study area was centered on the eastern plume of plutonium contamination and included transects extending from 0.2 km east of the primary origin of the contamination (the 903 Pad) to distances of up to 19 km northeast, east, southeast and south-southeast of the 903 Pad. Soil was collected in 3 cm layers down to 21 cm at exponentially increasing distances along the four transects. Plutonium concentrations decreased rapidly with depth, distance from the 903 Pad, and angle from due east. Depth distributions were independent of distance and angle from the 903 Pad, and our profile model can be used to adjust to a common basis, historical measurements made from sampling to different depths. Based on a total of approximately 1,400 independent measurements, mathematical functions were developed to describe the distance, directional, and depth relationships. These equations, combined with soil density and rock measurements, provided a new method to estimate the plutonium concentration or total deposition per unit area anywhere within the study area. Total deposition per unit area measurements at 50 sites provided an independent test of the model's predictive accuracy. Sampling coefficients of variation based on replicate samples at the main sampling locations averaged 33%, but ranged from 12 to 98%. The analytical measurement coefficient of variation averaged 8%. Mean 0-3 cm soil concentrations of (239,240)Pu among 10 Front Range "background" and 11 community locations near Rocky Flats were 2.1 and 2.3 Bq kg(-1), respectively.

Plutonium↗
PubMed1999

Resolving Nevada test site and global fallout plutonium in attic dust and soils using 137Cs/239+240Pu activity ratios.

A simple equation using only 137Cs/239+240Pu activity ratios was developed and evaluated as a means of resolving the plutonium in attic dust and soil from Nevada and Utah that came from Nevada Test Site fallout from that which came from global fallout. Applied to an historical data set of 137Cs and 239+240Pu activity concentrations in soils from Nevada and Utah, the activity ratio method gives results similar to the traditional 240Pu/239Pu isotope mass ratio method. Considering the difficulty and expense of determining the 240Pu/239Pu atom ratios, this activity ratio method is simpler, faster, and less costly, and may be useful for detecting and/or monitoring plutonium contamination in soils. Applied to samples of attic dust and soil collected from throughout southern Nevada and Utah during 1996 and 1997, it was found that all sites surveyed showed the presence of Nevada Test Site plutonium. Over 90% of the plutonium found in the samples from Beatty, Tonopah, and Queen City Summit, Nevada, can be attributed to the Nevada Test Site.

Cesium Radioisotopes↗
PubMed2002

A model for a comprehensive assessment of exposure and lifetime cancer incidence risk from plutonium released from the Rocky Flats Plant, 1953-1989.

A model was developed to calculate ambient air concentrations, surface deposition, and lifetime carcinogenic risk with uncertainty from plutonium released to the air from the Rocky Flats Plant between the years 1953 and 1989. The model integrated airborne release estimates and atmospheric dispersion and deposition calculations from 37 years of routine plant operations and episodic releases. Episodic releases included two major fires in 1957 and 1969 that breached the building air filtration systems, and suspension of plutonium contaminated soil from the former 903 waste storage area during high winds. Predicted air concentrations included contributions from site releases and resuspension from contaminated soil. Inhalation was the only exposure pathway considered. Environmental measurements suitable for model validation were lacking for the period when major site releases occurred (1953 to 1970). However, environmental media, such as soil and lake sediment, are natural accumulators and provided evidence of past offsite releases. The geometric mean predicted-to-observed (P/O) ratio for soil was 0.93 with a geometric standard deviation of 1.6. The model systematically underpredicted concentrations near the 903 Area because large, nonrespirable particles that deposited close to the source were not included in release estimates. Plutonium soil inventories for the model domain had P/O ratios ranging from 0.22 to 4.2. The geometric mean P/O ratio for ambient air was 0.90 with a geometric standard deviation of 2.6. Age-dated sediment cores from Standley Lake had a geometric mean P/O ratio of 1.0 with a geometric standard deviation of 1.7. Predicted-to-observed ratios for plutonium inventories in Great Western Reservoir ranged from 0.36 to 1.7. Lifetime cancer incidence risks were calculated for a male laborer scenario who resided in the model domain for the entire assessment time. Maximum cancer risks ranged from 10-6 (5th percentile) to 10(-4) (95th percentile). Most of the exposure was incurred during the 1950's.

Adult↗
PubMed2004

Relative role of plutonium excretion with urine and feces from human body.

The ratio of plutonium content in 35 pairs of daily fecal and urine samples from 19 former MAYAK workers several decades after the end of occupational exposure was measured in clinical conditions. No dependence of the ratio Pu(feces)/Pu(urine) on plutonium aerosol transportability, sex, and age of workers was revealed in the late times after the end of occupational exposure. It was found that at the late times after the end of occupational exposure, the ratio of feces/urine is characterized by the lognormal distribution with the median value, 0.57, and error for this index characterized geometric deviation, sigmag = 1.12 Urinary and fecal excretions were analyzed after chronic exposure to inhaled plutonium compounds of different transportability for another group of 345 workers. During 500-16,000 d after the started chronic inhalation, plutonium biokinetic model ("Doses-2000") used in Southern Ural Biophysics Institute (SUBI) and based on the ICRP Publication 66 overestimated the feces/urine ratio by an order of magnitude as compared with the observed values. It indicates a necessity for further improvement of the biokinetic model used in SUBI.

Administration, Inhalation↗
PubMed1986

Bronchoalveolar lavage: a new bioassay tool for plutonium inhalation exposures.

Existing methods for estimating lung burdens of radionuclides with low-energy gamma or x-ray emissions have limitations in their accuracy and availability. In this study, we evaluated the utility of bronchoalveolar lavage and assay of radioactivity in recovered lavage fluid as a bioassay tool to estimate lung burdens of plutonium. Six adult beagles briefly inhaled a polydisperse aerosol of 239PuO2, treated at 1150 degrees C, to achieve individual lung burdens of about 200 nCi. On the sixth day after exposure, a portion of each lung lobe of each dog was lavaged with 50 ml of saline. The dogs were killed, and tissue samples were obtained for radiochemical analysis. Using the relationship between regional deposition patterns of aerosols and the measured recoveries of plutonium in each lavage sample, the lung burden of each dog was estimated. The mean ratio for the lung burden estimates using lavage samples compared with the radiochemically determined lung burden was 1.0 +/- 0.6. This precision was similar to that obtained from in vivo measurement of plutonium x-rays, a standard bioassay procedure for plutonium inhalation cases. This suggests that the bronchoalveolar lavage technique may have applicability in situations where in vivo x-ray measurement is not feasible, or where lung burden estimates in addition to those obtained from in vivo measurement are valuable. The technique may also have utility for assessing inhalation exposures to other relatively insoluble materials, including nonradioactive chemicals.

Animals↗
PubMed2005

Adaptation of the ICRP publication 66 respiratory tract model to data on plutonium biokinetics for Mayak workers.

The biokinetics of inhaled plutonium were analyzed using compartment models representing their behavior within the respiratory tract, the gastrointestinal tract, and in systemic tissues. The processes of aerosol deposition, particle transport, absorption, and formation of a fixed deposit in the respiratory tract were formulated in the framework of the Human Respiratory Tract Model described in ICRP Publication 66. The values of parameters governing absorption and formation of the fixed deposit were established by fitting the model to the observations in 530 autopsy cases. The influence of smoking on mechanical clearance of deposited plutonium activity was considered. The dependence of absorption on the aerosol transportability, as estimated by in vitro methods (dialysis), was demonstrated. The results of this study were compared to those obtained from an earlier model of plutonium behavior in the respiratory tract, which was based on the same set of autopsy data. That model did not address the early phases of respiratory clearance and hence underestimated the committed lung dose by about 25% for plutonium oxides. Little difference in lung dose was found for nitrate forms.

Absorption↗
PubMed2006

Application of multi-compartment wound models to plutonium-contaminated wounds incurred by former workers at rocky flats.

This paper presents the analysis of urine bioassay data, spanning four decades, from five workers who had wounds contaminated with plutonium at the Department of Energy Rocky Flats Plant during the period 1961-1967. The cases were selected from participants in the Department of Energy-sponsored Former Radiation Worker Medical Surveillance Program at Rocky Flats, which provided medical monitoring, modern bioassay measurements, and internal dose re-evaluations for former Rocky Flats workers. The cases include a variety of wound types, excision treatment regimes, and monitoring information. These wound cases illustrate the use of two multi-compartment wound models and three plutonium urine excretion models for retrospective calculation of internal plutonium depositions resulting from wounds for which no chelation therapy was administered. Wound model compartment fractions and half times are determined for each case and urine excretion model as are composite parameter values. The urine analysis and wound count measurements obtained under the program provide data with state-of-the art measurement sensitivity, as well as the opportunity to include long-term excretion and wound site data that exceed 10,000 d post-exposure for retrospective intake and dose evaluations. These data are provided to the radiation dosimetry community for use in developing and testing improved models for plutonium deposition in wounds.

Adult↗