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Radioactivity concentrations of 137Cs and 40K in basidiomycetes collected in Taiwan.

Radioactivity concentrations of 137Cs and 40K in 64 mushroom samples belonging to 16 species of basidiomycetes collected at various locations in Taiwan have been measured in 1994. All of the samples were mushrooms cultivated indoors. The concentrations of 137Cs in many samples were below the limit of detection (< 1.0 Bq kg-1 dry weight), and 134Cs was not detected in any of the samples. The radioactivity concentration ranges of 137Cs and 40K in basidiomycetes were < 1.0-7.3 Bq kg-1 dry weight and < 50-1230 Bq kg-1 dry weight, respectively. The transfer factors of F. velutipes, G. lucidum and L. edodes from sawdust (growing substrate) to mushroom were approximately 10, 10.2, < 3.8 for 137Cs, and 7.2, 1.6, 1.8 for 40K, respectively. The effective dose equivalent due to the dietary intake of radiocesium through mushrooms for the Taiwanese people was estimated to be only 4.4 x 10(-10) Sv y-1.

Basidiomycota↗

PubMed2000

Removal of 125I from radioactive experimental waste with an anion exchange paper membrane.

The behavior of radioactive iodide and chloride ions through an anion exchange paper membrane to remove 125I from radioactive experimental waste has been studied with nonequilibrium thermodynamic analyses. Anion exchange paper membrane was found to be electroconductively more permeable to iodide ion than to chloride ion. The iodide ion bound more strongly to the anion exchange site within a membrane phase than the chloride ion by more than twice. The results suggested that an anion exchange paper membrane was appropriate for the filtration removal system.

Filtration↗

PubMed2001

Ferrate treatment for removing chromium from high-level radioactive tank waste.

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. This method could be generally applicable to removing chromium from chromium-contaminated solids, when coupled with a subsequent reduction of the separated chromate back to chromium(III). The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(II) molar ratio, but the chromium removal tends to level out for Fe(VI)/ Cr(III) greaterthan 10. Increasingtemperature leadsto better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be disposed as low-activity waste.

Chromium↗

PubMed2004

Mineral radioactivity in sands as a mechanism for fixation of organic carbon on the early Earth.

Irradiation of organic molecules by mineral radioactivity is a feasible alternative to cosmic irradiation to precipitate solid organic carbon-rich matter on the early Earth. Radioactive (uranium- and thorium-rich) minerals have been concentrated at the Earth's surface, and accumulated accretionary coatings of carbon due to irradiation, since early Archean times. The organic accretion process could have occurred at the surface or in the sub-surface, and is independent of a terrestrial or extraterrestrial source for the carbon.

Carbon↗

PubMed2004

Biofouling on the walls of a spent nuclear fuel pool with radioactive ultrapure water.

Microbial activity in spent nuclear fuel pools which contain ultrapure and radioactive water has been previously observed. The aim of the present research was to isolate and identify the microorganisms attached to the nuclear pool wall of a Spanish nuclear power plant. Amplification of 16S rDNA fragments from the culturable microorganisms by PCR using universal primers for the domain 'Bacteria', followed by Denaturing Gradient Gel Electrophoresis analysis revealed the presence of six different bacteria. The complete gene for 16S rDNA of each one was sequenced and identified as belonging to three different phylogenetic groups, viz. beta-Proteobacteria, Actinomycetales and the Bacillus/Staphylococcus group. A fungus was also found and identified as Aspergillus fumigatus by sequencing the D2 region of the large subunit rDNA gene. The isolation of these microorganisms in oligotrophic and radioactive conditions is of great interest due to the possibility of their use in bioremediation processes of radionuclide-contaminated environments.

Aspergillus fumigatus↗

PubMed1983

Solutions for the ICRP gastrointestinal activity from inhaled radioactive aerosols.

The International Commission on Radiological Protection (ICRP) has developed linear differential equations to define the movement of the fraction of inhaled radioactivity that goes to the gastrointestinal tract. These equations are based on assumed biological removal constants for each of three aerosol classes. The graphical method presented here allows the determination of the total number of nuclear transformations that occur in each gastrointestinal compartment when a given class aerosol is inhaled. The method takes into account the radioactive half-life of the isotope, the intestinal absorption fraction, and the aerosol size.

Aerosols↗

PubMed1992

Characterization of long-lived radioactive dust in uranium mill operations.

The characteristics of long-lived radioactive dust clouds generated in several mechanical and physiochemical operations in a uranium mill have been investigated. The study consisted of the determination of dust size distribution and of the size distribution of radionuclides associated with particulate matter in the size range less than 0.1 to 26 microns. Experiments were conducted by using two different types of cascade impactors operating at different sampling flow rates. Radionuclide identification was done by using alpha-spectrometry. Long- and short-lived radionuclides were identified in dust samples. The characteristics of the dust clouds depended on the mill operation, such as crushing (vibrating grizzly, jaw crusher, cone crusher); screening; ore transportation; grinding; acid leaching; counter-current decantation; yellow cake precipitation and drying; and yellow cake packaging. In addition, other dust and radioactivity measurements have been carried out.

Air Pollutants, Occupational↗

PubMed2003

Review of the radioactive waste management system in Nigeria.

The management of radioactive waste in Nigeria from early 1960 to date is reviewed. As in many developing countries, waste management in Nigeria has been shown to be ineffective. The factors that are responsible for this ineffectiveness are identified and discussed. The steps being taken by and the opportunities available to the newly established Nigerian Nuclear Regulatory Authority towards addressing this problem of ineffectiveness are discussed. The efforts of this newly set up body towards managing the resultant radioactive wastes that will be generated during the use of a reactor and an accelerator that will soon be commissioned in Nigeria are also mentioned. Likely ways of further addressing the problems militating against waste management in developing countries are suggested.

Developing Countries↗

PubMed2004

Controls on radioactivity in water supplies in England and Wales, with especial reference to radon.

This note describes the legal and administrative controls on concentrations of radioactive materials, with especial reference to radon, in drinking water in England and Wales. These controls follow the EC Drinking Water Directive and Recommendations from the European Union. The Directive relates to radioactivity in drinking water generally, while the Recommendations are specific to radon. A distinction is made between private and public supplies, with more stringent controls on the latter. In general, problems in meeting the recommended levels are not expected in England and Wales.

England↗

PubMed2002

Uranium and thorium series radionuclides in drinking water from drilled bedrock wells: correlation to geology and bedrock radioactivity and dose estimation.

Natural radioactivity in drinking water from 328 drilled wells was studied in correlation to source parameters. Poor correlation to both aquifer geology and bedrock radioactivity was observed. Concentrations of 238U, 226Ra, 228Ra, 222Rn and 210Po in groundwater samples was in the ranges <0.027-5.3, <0.016-4.9, <0.014-1.24, 5-8105 and <0.05-0.947 Bq.l(-1) respectively. In about 80% of the sites the radon concentration exceeds the Nordic recommended exemption level for radon in drinking water and 15% of the sites exceed the action limit. The effective doses from ingestion were calculated and presented in association with geology. Doses due to ingestion ranged between 0.05 and 20.4 mSv.y(-1), where the average contribution from 222Rn amounted to 75%. In comparison, the effective doses from inhalation of indoor 222Rn ranged between 0.2 and 20 mSv.y(-1). The average contribution from inhalation of 222Rn in air to the total effective dose (ingestion+inhalation) was 58 +/- 22%, 73 +/- 18% and 77 +/- 16% (1 SD) for the age categories 1 y, 10 y and adults respectively.

Air Pollution, Indoor↗

PubMed2005

Modelling of the shielding capabilities of the existing solid radioactive waste storages at Ignalina NPP.

There is only one nuclear power plant in Lithuania--Ignalina NPP (INPP). The INPP operates two similar units with design electrical power of 1500 MW. The units were commissioned in 1983 and 1987 respectively. From the beginning of the INPP operation all generated solid radioactive waste was collected and stored at the Soviet type solid radwaste facility located at INPP site. The INPP solid radwaste storage facility consists of four buildings, namely building No. 155, No. 155/1, No. 157 and No. 157/1. The buildings of the INPP solid radwaste storage facility are reinforced concrete structures above ground. State Nuclear Safety Inspectorate (VATESI) has specified that particular safety analysis must be performed for existing radioactive waste storage facilities of the INPP. As part of the safety analysis, shielding capabilities of the walls and roofs of these buildings were analysed. This paper presents radiation shielding analysis of the buildings No. 157 and No. 157/1 that are still in operation. The buildings No. 155 and No. 155/1 are already filled up with the waste and no additional waste loading is expected.

Computer Simulation↗

PubMed2006

In situ long-term monitoring system for radioactive contaminants.

A long-term in situ subsurface instrument for monitoring radioactive contaminant plumes, as an alternative to soil analysis, is described. A portable, laser-based reader optically stimulates luminescence from sensors, each containing an Al2O3:C dosemeter. The sensors, designed for placement at various subsurface locations around a waste site, are allowed to accumulate dose for a predetermined time that is based on the instrument's minimum detectable dose (MDD). The reader is then attached to the sensor by fibre optic cable to read the accumulated dose; an increase above natural background levels indicating the presence of leaked radioactivity. Based on an MDD of 5 microGy, it is shown that the sensor can measure soil concentrations of 1.85 Bq cm(-3) after an exposure time of 50 h for 137Cs and 67 h for 90Sr/90Y. Discrimination between beta and gamma radiation is possible using an end cap placed over one of the two paired sensors, allowing simultaneous measurement of 137Cs and 90Sr/90Y in a mixed field. The monitor system represents a substantial improvement over quarterly soil sampling because of a greatly increased measurement frequency and the ability to perform measurements reproducibly.

Dose-Response Relationship, Radiation↗

PubMed1991

Radioactive tracer techniques in the sequencing of glycoprotein oligosaccharides.

Complete sequencing of the oligosaccharide units of glycoproteins can be performed by conventional physical techniques if nanomole quantities of pure molecules are available. However, isolation of sufficient quantities of a glycoprotein may not be technically feasible (e.g., the analysis of biosynthetic intermediates, or rare molecules). Alternatively, partial structural analyses may answer the biological question at hand. In both instances, radioactive sugars can be used to metabolically label the oligosaccharide units of a glycoprotein, permitting substantial structural characterization. Several aspects of this approach are discussed in this overview, including selection of the labeled precursor, maximization of uptake and incorporation, determinants of the specificity of labeling, and general principles for the release and structural analysis of labeled oligosaccharides. Particular advantages include simplicity, ease of use without sophisticated instrumentation, and the fact that purification to radiometric homogeneity is sufficient. Radioactive tracer techniques cannot replace conventional approaches to sequencing oligosaccharides. However, they do provide a rapid, relatively simple approach to obtaining considerable information from limited amounts of material. For molecules such as short-lived biosynthetic intermediates, there is no substitute for these techniques. This approach has been responsible for the initial identification and characterization of many novel oligosaccharides of biological interest.

Animals↗

PubMed1982

Doses received while crossing a plume of radioactive material released during an accident at a nuclear power plant.

A set of calculations was performed to determine doses resulting from a release of radioactive material during a hypothetical serious accident at a nuclear power plant. Three different accident scenarios were considered, and calculations were performed for each of three meteorological conditions accompanying each accident scenario. The calculated doses were the doses received by a reference man traversing the entire width of the plume of radioactive material at distances ranging from one to 40km downwind of the release site. Dose pathways considered included the internal dose due to inhalation of material in the plume, the external dose due to exposure to the plume, and the external dose due to ground contamination deposited by the passing plume. The calculated doses are presented along with a discussion of their implications for emergency response planning.

Air Pollution, Radioactive↗

PubMed1983

Biological elimination rates of radioisotopes by mallards contaminated at a liquid radioactive waste disposal area.

The biological elimination of nine gamma-emitting radioisotopes was studied in mallards (Anas platyrhynchos) which were released onto liquid radioactive waste pounds in southeastern Idaho. After 68, 75 or 145 days, the ducks were removed from the contaminated environment and placed in metabolic cages. Whole-body and feces-urine counts were made for 51 days and then the ducks were sacrificed and dissected for tissue analyses. The biological elimination of radioisotopes were fit to two compartment models using non-linear least squares estimation. Fecal-urine data substantiated two-compartment elimination of all radionuclides. Biological half-lives in mallards were 10 days (131I), 22 days (140Ba), 86 days (51Cr), 32 days (58Co), 26 days (75Se), 67 days (65Zn), 10 days (134Cs), 67 days (60Co) and 11 days (137Cs). Body burdens in ducks were at 90% of equilibrium with the radioactive waste pond water at the time of removal from the waste ponds. Tissue distribution of radionuclides on the day of removal from the ponds showed gut to have the highest concentrations followed by feather, liver and muscle. After 51 days in metabolic cages, feather had the greatest radionuclide concentrations followed by liver, muscle and gut. Liver contained the greatest variety of radionuclides and muscle the smallest. Biological elimination rates for the major dose-contributing nuclides (134Cs and 137Cs) to humans consuming contaminated waterfowl tissue indicate that the dose to man could be reduced substantially due to the rapid elimination of these radionuclides by mallards. Contaminated waterfowl would receive most of the internal dose in the first month after leaving the contaminated environment indicating that long-term doses would be inconsequential.

Animals↗

PubMed1984

The calculation of total transformations in organs following the inhalation of radioactive aerosols of different sizes.

A technique is presented which makes use of the ICRP methodology for calculating the total number of transformations in an organ following the inhalation of radioactive aerosols of various half-lives and activity median aerodynamic diameters (AMADs). As found in studies involving respiratory and gastrointestinal tract activities under similar conditions, there are constants common to the aerosol class which allow the plotting of factors which depend only upon the radioactive half-life of the isotopes involved. The method shows the influence of respiratory uptake on the total number of transformations in the organ as well as the influence of AMAD and the route the isotope takes to the organ, e.g. directly from the respiratory tract or via the gastrointestinal tract. Although the technique is more complicated than that used for the respiratory or gastrointestinal tract uptake, the method requires a minimum of calculation.

Aerosols↗

PubMed1984

An electrostatic precipitator for the study of airborne radioactivity.

An system has been developed to measure airborne radioactivity using electrostatic precipitation for collection and alpha-particle spectroscopy for detection. Features include good energy resolution (e.g. 170 and 300 KeV for full-width half maximum and full-width tenth maximum for 7.7-MeV alpha particles using a 7-cm2 area detector; and 52- and 122-KeV, respectively, using 1.2-cm2 area detector) and versatile computer control for collection, counting and data reduction. Aerosols bearing the radioactive atoms are deposited on a foil tape by electrostatic precipitation for a predetermined time after which the foil is moved under a solid-state detector to count the alpha-particle emissions. Activities are determined at the same frequency as samples are collected. Helium gas can be introduced at the detector to reduce energy loss and improve resolution. Although in principle certain aerosol sizes could be difficult to collect, in practice no difficulties were observed for typical environmental conditions, provided sufficiently low air-sampling rates were used. One important application is the measurement of 222Rn daughters. The sensitivity is such that detection of individual daughter concentrations less than 0.1 pCi/l. with only a 10% counting error is possible.

Air Pollution, Radioactive↗

PubMed1984

Iodine-129 in waterfowl muscle from a radioactive leaching pond complex in southeastern Idaho.

Waterfowl were collected at radioactive leaching ponds, an adjacent sewage lagoon on the Idaho National Engineering Laboratory ( INEL ) and on nearby control areas to determine 129I / 127I (stable isotope) atom ratios in muscle tissue. Iodine-129/127 atom ratios in muscle tissue averaged about 1.6 X 10(-6) for wild waterfowl from the leaching pond, 1.6 X 10(-6) for waterfowl from the sewage pond, and 1.3 X 10(-6) for control samples. A group of wing-clipped waterfowl placed on the ponds for 2-156 days had average 129I / 127I atom ratios in muscle of 6.0 X 10(-6). Iodine-129/127 atom ratios in muscle were statistically higher (P less than 0.05) in the wing-clipped waterfowl than in control, sewage lagoon and wild waterfowl samples because of the extended period of time they spent on the ponds. Internal lifetime whole-body dose from 129I was estimated to be 1.0 X 10(-5) mrad for waterfowl from control areas and 3.0 X 10(-5) mrad for leaching pond waterfowl. The lifetime thyroid dose commitment to man consuming a wild duck from the leaching ponds was 1.3 X 10(-4) mrem. Liquid effluents disposed in the radioactive leaching ponds do not appear to cause an appreciable increase in 129I / 127I atom ratios in tissues of waterfowl using the ponds.

Animals↗