7 research outputs found
Recommended from our members
Water sorption mechanisms for MIS materials.
The fundamental processes that control the amount of water sorbed by impure plutonium-containing materials after calcination are reviewed. Of particular interest is the amount of and rate of moisture sorption at 1000 PPMv (parts-per-million vapor; -3% RH at 25 'C) and 10,000 PPMv (32% RH at 25 'C). Pure plutonium oxide powders will remain below the 0.5 wt% criterion for packaging in the DOE 3013 Standard at both water vapor concentrations [I]. Deliquescent salts that have been observed in calcined materials by DOES Materials Identification and Surveillance (MIS) program will exceed the 0.5 wt% criterion at 10,000 PPMv and will meet that standard at 1,000 PPMv. Hydrated salts will exceed the 0.5 wt% criterion at all technologically achievable water vapor concentrations if allowed to reach equilibrium. Controlling the moisture availability by controlling the atmospheric content at 1000 PPM' and limiting the access to atmospheric moisture after stabilization through the use of a properly configured stabilization boat will minimize moisture uptake by these materials
Recommended from our members
Transuranic actinide reactions with simple gas-phase molecules.
The intent of this research is to conduct an experimental study of f-element chemistry fo r the purpose of identifying reaction trends and mechanisms of the early actinide metals with simple gas phase molecules . Previous research has elucidated some of the fundamenta l chemistry of the 4f elements,1-5 however, more complex chemistry is expected for the 5f serie s due to the inclusion of the 5f electrons in the valence shell . The matrix isolation approach, which is well-suited to the experimental study of transient species, will be used for sample collection, and IR/NIR/VIS spectroscopy will be employed to interrogate deposited matrices . The strength of this method lies in the use of isotopes of reactants, which permits the identification of guest molecules in a noble gas matrix by observation of vibrational frequenc y shifts and patterns upon isotopic substitution . Using this technique at the University of Virginia, the first noble gas-actinide bond has recently been identified, a weak U-Ar bond on the CUO molecule.6 Uranium has similarly been observed to bond to krypton and xenon, whereas thoriu m and the lanthanides have not exhibited this activity . It is expected that plutonium will be even more reactive in this respect . We will extend the body of actinide experimental evidence t o include the transuranic elements neptunium, plutonium, and americium reacted with isotopes o f oxygen, nitrogen, hydrogen, carbon monoxide, and carbon dioxide
Recommended from our members
Analysis of gas constituents from sealed containers of plutonium oxide materials.
The safe storage of pure and impure plutonium oxide materials in sealed containers is a current Department of Energy (DOE) concern. Plutonium oxides sorb moisture from the atmosphere, and the subsequent radiolytic and/or chemical decomposition of the water has been thought to generate excessive hydrogen pressures inside sealed containers. Eleven sealed containers with ten grams each of plutonium oxide materials have been studied for up to four years. The sealed materials were representative materials from the DOE complex and contain less than 0.5 weight percent water. The samples were kept at ambient conditions. We report the final gas analysis of the headspace gas of these containers using gas chromatography, mass spectrometry and Raman spectroscopy. The results show that none of the containers have pressurized significantly, and that hydrogen was not generated in significant quantities
Recommended from our members
Gas generation over plutonium oxides in the 94-1 shelf-life surveillance program.
The Department of Energy (DOE) is embarking upon a program to store large quantities of plutonium-bearing materials for up to fifty years. The Los Alamos National Laboratory Shelf Life Project was established to bound the behavior of plutonium-bearing material meeting the DOE 3013 Standard. The shelf life study monitors temperature, pressure and gas composition over oxide materials in a limited number of large-scale 3013 inner containers and in many small-scale containers. For the large-scale study, baseline plutonium oxides, oxides exposed to high-humidity atmospheres, and oxides containing chloride salt impurities are planned. The first large-scale container represents a baseline and contains dry plutonium oxide prepared according to the 3013 Standard. This container has been observed for pressure, temperature and gas compositional changes for less than a year. Results indicate that no detectable changes in pressure and gas composition are observed
Recommended from our members
Prediction of gas pressurization and hydrogen generation for shipping hazard analysis : Six unstabilized PU 02 samples
Radiolysis of water to form hydrogen gas is a safety concern for safe storage and transport of plutonium-bearing materials. Hydrogen gas is considered a safety hazard if its concentration in the container exceeds five percent hydrogen by volume, DOE Docket No. 00-1 1-9965. Unfortunately, water cannot be entirely avoided in a processing environment and these samples contain a range of water inherently. Thermodynamic, chemical, and radiolysis modeling was used to predict gas generation and changes in gas composition as a function of time within sealed containers containing plutonium bearing materials. The results are used in support of safety analysis for shipping six unstabilized (i.e. uncalcined) samples from Rocky Flats Environmental Technology Sits (RFETS) to the Material Identification and Surveillance (MIS) program at Los Alamos National Lab (LANL). The intent of this work is to establish a time window in which safe shipping can occur
Recommended from our members
Gas generation by pure and impure plutonium oxide materials in sealed containers.
The Department of Energy (DOE) standard, DOE-STD-3013-2000, establishes criteria for stabilizing, packaging, and long term safe storage of plutonium-bearing materials at DOE facilities . The Standard applies to oxide or metal that contains at least 30 weight percent plutonium plus uranium. For oxide material a maximum of 5 kg of material is packaged in a nested set of two individually welded containers and the requirements include material stabilization at 950 C, 0 .5 weight percent moisture content or less, and less than nineteen watts of power per sealed container . The welded containers ensure that any gas generated due to radiolysis will be retained within the container . Although the 3013 package provides for a robust storage system, its long-term safety performance has not been demonstrated . To ensure failures do not occur while the sealed containers are being stored for up to 50 years, a DOE complex-wide integrated surveillance program has been established to measure the gas generation rates of these materials. At Los Alamos National Laboratory (LANL), the shelf life project monitors gases over oxide materials in a limited number of large-scale 3013 inner containers charged with 5 kg of material and in many small-scale containers with 10 gram samples taken from site-wide representative materials actually being stored . The small-scale containers allow more sample types and conditions to be studied. This information provides invaluable, defensible results for assuring safe long-term storage of these materials in sealed containers . Initial results on gas generation are presented
Recommended from our members
Introducing equipment and plutonium glove box modifications for monitoring gas generation over plutonium oxide materials.
DOE is embarking on a program to store large quantities of Pu-bearing materials for up to fifty years. Materials for long-term storage are metals and oxides that are stabilized and packaged according to the DOE storage standard. Experience with PuO, materials has shown that gases generated by catalytic and/or radiolytic processes may accumulate. Of concern are the generation of H, gas from adsorbed water and the generation of HCI or CI, gases from the radiolysis of chloride-containing salts. We have designed instrumented storage containers that mimic the inner storage can specified in the standard. The containers and surveillance equipment are interfaced with a plutonium glovebox and are designed to allow the gas composition and pressure to be monitored over time. The surveillance activities and glovebox interfaces include Raman fiber optic probes, a gas analysis sampling port, corrosion monitors, and pressure and temperature feedthrus. Data collection for these containers is automated in order to reduce worker exposure. The equipment design and glovebox modifications are presented