Contamination, plutonium

Plutonium (Pu) is an artificial element of atomic number 94 that has its main radioactive isotopes at 2 °Pu and Pu. The major sources of this element arise from the manufacture and detonation of nuclear weapons and from nuclear reactors. The fallout from detonations and discharges of nuclear waste are the major sources of plutonium contamination of the environment, where it is trapped in soils and plant or animal life. Since the contamination levels are generally very low, a sensitive technique is needed to estimate its concentration. However, not only the total amount can be estimated. Measurement of the isotope ratio provides information about its likely... 

Cooper MB, Bums PA, Tracy BL, et al. 1994. Characterization of plutonium contamination at the former nuclear weapons testing range at Maralinga in South Australia. J Radioanal Nucl Chem 177(1) 161-184. 

DOE. 1979c. Summary report of the grazing studies conducted on a plutonium-contaminated range in area 13 of the Nevada test site. Washington, DC U.S. Department of Energy. NTIS/EMSL-LV-0539-24. 

Plutonium contamination resulted from missile test failures in the 1960s. 

Allhough Ihe ceramification and SYNROC lechnologies are being researched to develop a final waste form for plutonium-contaminated materials, no experiments with plutonium have been performed. The SMITE process is designed for the treatment of solid, inorganic materials. The final waste form will leach in acidic solutions so storage in a basic environment is recommended. 

Montero, P. R. Sanchez, A. M. 2001. Plutonium contamination from accidental release or simply fallout study of soils at Palomares (Spain). Journal of Environmental Radioactivity, 55, 157-165. 

A lthough the levels of plutonium in environmental waters are generally - low, there is the possibility of plutonium contamination from weapons testing, nuclear reactor operations, laundry and decontamination wastes, fuel reprocessing, and accidental release during transportation. It has been estimated that by 1980 the United States will be producing 15,000-20,000 kg. of plutonium per year (12). Its growing use will increase the probability of environmental contamination. 

Krey, P.W. (1976) Remote plutonium contamination and total inventories from Rocky Flats. Health Physics, 30, 209-14. 

Plutonium-contaminated waste, principally from weapons materials processing. There are two classes of plutonium wastes the transuranic, containing mostly plutonium and other transuranics, and the high-level wastes that contain significant heat-generating products, strontium, and cesium. 

The reported solubility product of Pu(0H)i+, 7 X 10 as measured by pH titration ( 3, p. 300), is an exceedingly small number. If it were a true representation of the concentration of plutonium in solution, at pH 7 there would be only 7 X 10 mole of plutonium per liter thus the equilibrium concentration of plutonium in neutral water would be about one atom per 2400 liter and there would be no problem with plutonium-contaminated ground water. The solubility product does not accurately define the concentration of plutonium in aqueous solutions because it merely states the concentration of the Pu " " ion. At pH values of environmental interest, plutonium will be present not primarily as Pu " , but as species such as Pu(OH) " ", Pu(OH), unionized Pu(0H)4, colloidal polymeric forms to be discussed later, as well as other oxidation states formed by disproportionation at low acidities. Thus, the total plutonium concentration will be much higher than that described by the solubility product of Pu(0H)i. ... 

Improved rapid sample preparation methods were developed for plutonium and analysis by alpha-spectrometry and ICP-SFMS techniques. The methods were applied for the analysis of various samples from highly contaminated and less-contaminated sites. It was demonstrated that using different isotope ratios obtained both by mass spectrometry and alpha-spectrometry as complementary tools the source of plutonium contamination can be assessed and retrospective investigation is possible. 

Alpha-bearing wastes (also called transuranic, plutonium-contaminated material, or alpha wastes) include wastes that are contaminated with enough long-lived, alpha-emitting nuclides to make near-surface disposal unacceptable. They arise principally from spent fuel reprocessing and mixed-oxide fuel fabrication. The wastes may he disposed of in a similar manner to HLW. 

The plutonium contamination close-in at Taranaki is mainly in three forms, viz. as a fine dust, as small sub-millimetre particles, and as surface contamination on larger fragments (Bums et al., 1986). In the trials, the plutonium was dispersed in narrow plumes, the main ones extending to the west, north-west, north and north-east of Taranaki. The most extensive of these is the north-west plume, which can be detected crossing West Street between Fifth and Tenth Avenues (Fig. 10.10). In the central area... 

A technique more suited to this particular situation is that of in-situ gamma-ray spectrometry using a portable germanium detector. This is the method which has been employed in the study by Johnston et al. (1989), conducted during 1987 and 1988, to detect plutonium contamination at levels well below 1 kBq m ... 

Cooper et al. (1994) have reported re-suspension studies on soils contaminated with plutonium during nuclear weapons tests by use of a mechanical dust-raising apparatus. Airborne dust was analysed in terms of mass and Am activities for particle sizes less than 7 pm. The AMAD was determined as 4.8-6 pm for re-suspended soil. Also, surface soil was characterised in the laboratory by means of sieving and microparticle classification, yielding mass and "Am activity distribution with respect to size. Data indicate the granularity of plutonium contamination at both major and minor trial sites. Depth profile analyses for undisturbed areas demonstrate that most (74% on average) of the americium and plutonium activity is found in the top 10 mm of soil. Plutonium and americium activities were found to be enhanced in the inhalable fraction over their values in the total soil, and the enhancement factors were similar in re-suspended dust and surface soil. Observed enhancement factors ranged from 3.7 to 32.5. 

During this period several studies have been performed in this area. Let us only mention the report by Simon et al. (1995) in which plutonium-contaminated soil from the Republic of the Marshall Islands has been studied to determine the spatial and volume characteristics of contamination on two scales (1) in macroscopic masses, i.e., gram sized samples, and (2) in microscopic masses, i.e., tens of pg to 1 mg. Three measures of volumetric homogeneity calculated from alpha track measurements on a plastic track detector (CR-39) were performed to quantitatively assess microspatial or microvolumetric variations. 

Bums, P.A., Cooper, M.B., Duggleby, J.C., Mika, J.F. and Williams, G.A., Plutonium-contaminated fragments at the Taranaki site at Maralinga, ARL/TR075, July 1986. 

Johnston, P.N., Lokan. K.H., Richardson, C.K. and Williams, G.A., Plutonium contamination in the Maralinga TJarfJe Lands Report ARL/TR085, ISSN 0157-1400, August 1989. 

Since 1958, more than 20 nuclides of actinides ranging from neptunium to einsteinium were identified and prepared for tracer studies. From neutron-irradiated uranium samples 2 9Np was adjusted to the pentavalent state and separated by TBP extraction from perchloric acid media. Plutonium-239 was separated by TBP extraction from nitric acid solution followed by anion exchange in a system of Dowex-1 resin and nitric acid. Neptunium-237 was separated from a spent fuel solution of JRR-1 (Japan Research Reactor -1) using anion exchange and TBP extraction. The TBP extraction in the hydrochloric acid medium is a simple and effective technique to purify neptunium from plutonium contamination. On the other hand, both anion exchange and solvent extraction with HDEHP could be used to separate tracer scale plutonium from irradiated neptunium targets. 

Delayed treatment with multiple doses of DTPA removes moderate amounts of plutonium from animals. Treatment of swine on five successive days two months after plutonium contamination removed 11—19% of the plutonium 9S). The body burden of rats was reduced to 60% of the controls by treatment with DTPA administered on day 6, 8 and 11 after the plutonium injection99). The largest decrease of plutonium was found in the soft tissues, but skeletal removal was more difficult, and the moderate amounts removed may not significantly reduce the number of bone tumors formed59 100 101). Further details on the use of DTPA in removing internally deposited plutonium may be gained from other reviews6 13 102 103). 

Using equation [7] and x = 5-6 years, the frequency distribution of an instantaneous plutonium contamination for different boxes and different times was computed. When i is used a a variable, t as a fixed parameter, the penetration of 50% of transported contamination can be estimated after summing up the distribution frequencies. From this and from the corresponding times, the transportation velocity of PuOo is obtained very easily (Table I). 

The relative migration velocity of plutonium contamination when applied to soil in the form of a Pu(N03)4 solution rN may be given by... 

Plutonium wastes from the Los Alamos National Laboratory in northern New Mexico were trucked for the first time to the federal Waste Isolation Pilot Plant in Carlsbad in March 1999. The 600 pounds (270 kg) of waste consisted of plutonium-contaminated clothing and metal cans, packed in boxes and stainless steel containers. Most of the material was from the laboratory s manufacture of nuclear batteries used in NASAs deep space probes and will be buried in the depository carved out of ancient salt caverns about half a mile (0.8 km) below ground. 

Plutonium-contaminated wastes, which mainly comprise paper, gloves, and contaminated, unserviceable equipment fix)m the maintenance of plants handling plutonium, can be treated in the following ways combustible waste—incineration and acid digestion and noncombustible waste— decontamination by electropolishing or ultrasonic washing. 

Although incineration is used widely for volume reduction of industrial and household combustible waste, the incineration process for plutonium-contaminated waste has required very special development to ensure protection of the operators, efficient ofiF-gas cleaning to protect the environment, and the avoidance of criticality owing to the concentration of plutonium in the ash. An incinerator for this duty now has been operated successfully in the United Kingdom on a pilot-plant scale and it... 

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