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Gas Generation Testing of Neptunium Oxide Generated Using the HB-Line Phase IIFlowsheet

Description: The hydrogen (H{sub 2}) gas generation rate for neptunium dioxide (NpO{sub 2}) samples produced on a laboratory scale using the HB-Line Phase II flowsheet has been measured following exposure to 75% relative humidity (RH). As expected, the observed H{sub 2} generation rates for these samples increase with increasing moisture content. A maximum H{sub 2} generation rate of 1.8 x 10{sup -6} moles per day per kilogram (mol {center_dot} day{sup -1} kg{sup -1}) was observed for NpO{sub 2} samples with approximately one and one-half times (1 1/2 X) the expected specific surface area (SSA) for the HB-Line Phase II product. The SSA of NpO{sub 2} samples calcined at 650 C is similar to plutonium dioxide (PuO{sub 2}) calcined at 950 C according to the Department of Energy (DOE) standard for packaging and storage of PuO{sub 2}. This low SSA of the HB-Line Phase II product limits moisture uptake to less than 0.2 weight percent (wt %) even with extended exposure to 75% RH.
Date: August 29, 2003
Creator: Duffey, J
Partner: UNT Libraries Government Documents Department

Lab Scale Production of NpO2

Description: The Savannah River Site (SRS) plans to disposition its legacy H-Canyon neptunium to Oak Ridge National Laboratory after converting it to oxide in HB-Line. Neptunium oxide, (NpO{sub 2}) was produced at the Savannah River Technology Center using the anticipated HB-Line flowsheet conditions. The oxide was produced from a neptunium nitrate solution via anion exchange, oxalate precipitation, and calcination at either 600 C or 650 C. The 98 grams of NpO{sub 2} produced in the laboratory should be representative of material produced in HB-Line and is to be used for gas generation testing to support radioactive material transportation safety analysis as part of the neptunium stabilization and disposition program at SRS. Results of each step of the oxide production will be presented.
Date: August 29, 2003
Creator: Duffey, J
Partner: UNT Libraries Government Documents Department

Characterization of Neptunium Oxide Generated Using the HB-Line Phase II Flowsheet

Description: Approximately 98 grams of neptunium(IV) oxide (NpO{sub 2}) were produced at the Savannah River Technology Center (SRTC) for use in gas generation tests to support the neptunium stabilization program at the Savannah River Site (SRS). The NpO{sub 2} was produced according to the anticipated HB-Line flowsheet consisting of anion exchange, oxalate precipitation, filtration, and calcination. Characterization of the NpO{sub 2} product to be used in gas generation tests included bulk and tap density measurements, X-ray diffraction, particle size distribution, specific surface area measurements, and moisture analysis.
Date: August 29, 2003
Creator: Duffey, J
Partner: UNT Libraries Government Documents Department

Hydrogen Generation Scoping Study of Surrogate WSB Concrete Waste Forms

Description: The Department of Energy (DOE) plans to build a Waste Solidification Building (WSB) at the Savannah River Site (SRS) in South Carolina. The project is currently in the preliminary design phase. In this scoping study surrogate radioactive concrete waste forms were prepared at water-to-cement mass ratios (w/c) of 0.2 and 0.3 and sealed in pressure vessels. Pressure and temperature were recorded electronically for the duration of the test. After about 11 days, the headspace gas of each vessel was sampled and analyzed by gas chromatography for hydrogen, oxygen, and nitrogen content. The data collected during these tests were used to estimate hydrogen gas generation rates and hydrogen G-values (molecules of hydrogen produced per 100 eV radioactive decay energy deposited) for waste forms prepared at each w/c ratio.
Date: October 29, 2003
Creator: Duffey, J.M.
Partner: UNT Libraries Government Documents Department

PRESSURE DEVELOPMENT IN SEALED CONTAINERS WITH PLUTONIUM BEARING MATERIALS

Description: Gas generation by plutonium-bearing materials in sealed containers has been studied. The gas composition and pressure are determined over periods from months to years. The Pu-bearing materials studied represent those produced by all of the major processes used by DOE in the processing of plutonium and include the maximum amount of water (0.5% by weight) allowed by DOE's 3013 Standard. Hydrogen generation is of high interest and the Pu-bearing materials can be classed according to how much hydrogen is generated. Hydrogen generation by high-purity plutonium oxides packaged under conditions typical for actual 3013 materials is minimal, with very low generation rates and low equilibrium pressures. Materials with chloride salt impurities have much higher hydrogen gas generation rates and result in the highest observed equilibrium hydrogen pressures. Other materials such as those with high metal oxide impurities generate hydrogen at rates in between these extremes. The fraction of water that is converted to hydrogen gas as equilibrium is approached ranges from 0% to 25% under conditions typical of materials packaged to the 3013 Standard. Generation of both hydrogen and oxygen occurs when liquid water is present. The material and moisture conditions that result in hydrogen and oxygen generation for high-purity plutonium oxide and chloride salt-bearing plutonium oxide materials have been characterized. Other gases that are observed include nitrous oxide, carbon dioxide, carbon monoxide, and methane.
Date: February 1, 2010
Creator: Duffey, J. & Livingston, R.
Partner: UNT Libraries Government Documents Department

SRNL PHASE II SHELF LIFE STUDIES - SERIES 1 ROOM TEMPERATURE AND HIGH RELATIVE HUMIDITY

Description: The Savannah River National Laboratory (SRNL) Phase II, Series 1 shelf-life corrosion testing for the Department of Energy Standard 3013 container is presented and discussed in terms of the localized corrosion behavior of Type 304 stainless steel in contact with moist plutonium oxide and chloride salt mixtures and the potential impact to the 3013 inner container. This testing was designed to address the influence of temperature, salt composition, initial salt moisture, residual stress and type of oxide/salt contact on the relative humidity inside a 3013 container and the initiation and propagation of localized corrosion, especially stress corrosion cracking. The integrated plan is being conducted by Los Alamos National Laboratory and SRNL. SRNL is responsible for conducting a corrosion study in small scale vessels containing plutonium oxide and chloride salts under conditions of humidity, temperature and oxide/salt compositions both within the limits of 3013 storage conditions as well as beyond the 3013 storage requirements to identify margins for minimizing the initiation of stress corrosion cracking. These worst case conditions provide data that bound the material packaged in 3013 containers. Phase I of this testing was completed in 2010. The Phase II, Series 1 testing was performed to verify previous results from Phase I testing and extend our understanding about the initiation of stress corrosion cracking and pitting that occur in 304L under conditions of room temperature, high humidity, and a specific plutonium oxide/salt chemistry. These results will aid in bounding the safe storage conditions of plutonium oxides in 3013 containers. A substantial change in the testing was the addition of the capability to monitor relative humidity during test exposure. The results show that under conditions of high initial moisture ({approx}0.5 wt%) and room temperature stress corrosion cracking occurred in 304L teardrop coupons in contact with the oxide/salt mixture at times as ...
Date: September 12, 2012
Creator: Mickalonis, J. & Duffey, J.
Partner: UNT Libraries Government Documents Department

RELATIVE HUMIDITY TESTS IN SUPPORT OF THE 3013 STORAGE AND SURVEILLANCE PROGRAM

Description: Techniques to control the initial relative humidity over oxide/salt mixtures have been developed using cerium oxide as a surrogate for plutonium oxide. Such control is required to validate certain assumptions in the Department of Energy Standard DOE-STD-3013, and to provide essential information to support field surveillance at the storage sites for excess plutonium oxides. Concern over the validity of the assumption that corrosion induced degradation in 3013 containers could be controlled by assuring that the moisture content of any stored oxide/salt mixture was below 0.5 w t% arose when stress corrosion cracks were found in test samples exposed at room temperature to plutonium oxide/salt mixtures having a moisture content only marginally above 0.5 wt %. Additionally, analysis of the stress corrosion cracking observations suggests that the initial relative humidity over the oxide/salt mixture may play a major role in the cracking process. The investigations summarized in this report provide the procedures necessary to control the initial relative humidity to selected values within the range of 16 to 50% by controlling the loading relative humidity (18 to 60%) and the oxide/salt mixture water content (0.05 to 0.45 wt %). The studies also demonstrated that the initial relative humidity may be estimated by calculations using software EQ3/6. Cerium oxide/salt mixtures were used in this study because qualification tests with non-radioactive materials will reduce costs while increasing the breadth of the test programs required to support field surveillances of stored 3013 containers.
Date: August 1, 2011
Creator: Mickalonis, J. & Duffey, J.
Partner: UNT Libraries Government Documents Department

TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM DIOXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE

Description: This report documents the technical basis for determining that stabilizing highpurity PuO{sub 2} derived from oxalate precipitation at the SRS HB-Line facility at a minimum of 625 {degree}C for at least four hours in an oxidizing atmosphere is equivalent to stabilizing at a minimum of 950 {degree}C for at least two hours as regards meeting the objectives of stabilization defined by DOE-STD-3013 if the material is handled in a way to prevent excessive absorption of water.
Date: February 6, 2013
Creator: Duffey, J. M.; Livingston, R. R.; Berg, J. M. & Veirs, D. K.
Partner: UNT Libraries Government Documents Department

MOISTURE AND SURFACE AREA MEASUREMENTS OF PLUTONIUM-BEARING OXIDES

Description: To ensure safe storage, plutonium-bearing oxides are stabilized at 950 C for at least two hours in an oxidizing atmosphere. Stabilization conditions are expected to decompose organic impurities, convert metals to oxides, and result in moisture content below 0.5 wt%. During stabilization, the specific surface area is reduced, which minimizes readsorption of water onto the oxide surface. Plutonium oxides stabilized according to these criteria were sampled and analyzed to determine moisture content and surface area. In addition, samples were leached in water to identify water-soluble chloride impurity content. Results of these analyses for seven samples showed that the stabilization process produced low moisture materials (< 0.2 wt %) with low surface area ({le} 1 m{sup 2}/g). For relatively pure materials, the amount of water per unit surface area corresponded to 1.5 to 3.5 molecular layers of water. For materials with chloride content > 360 ppm, the calculated amount of water per unit surface area increased with chloride content, indicating hydration of hygroscopic salts present in the impure PuO{sub 2}-containing materials. The low moisture, low surface area materials in this study did not generate detectable hydrogen during storage of four or more years.
Date: September 28, 2009
Creator: Crowder, M.; Duffey, J.; Livingston, R.; Scogin, J.; Kessinger, G. & Almond, P.
Partner: UNT Libraries Government Documents Department

TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM OXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE

Description: The HB-Line (HBL) facility at the Savannah River Site (SRS) is designed to produce high-purity plutonium dioxide (PuO{sub 2}) which is suitable for future use in production of Mixed Oxide (MOX) fuel. The MOX Fuel Fabrication Facility (MFFF) requires PuO{sub 2} feed to be packaged per the U.S. Department of Energy (DOE) Standard 3013 (DOE-STD-3013) to comply with the facility's safety basis. The stabilization conditions imposed by DOE-STD-3013 for PuO{sub 2} (i.e., 950 C for 2 hours) preclude use of the HBL PuO{sub 2} in direct fuel fabrication and reduce the value of the HBL product as MFFF feedstock. Consequently, HBL initiated a technical evaluation to define acceptable operating conditions for production of high-purity PuO{sub 2} that fulfills the DOE-STD-3013 criteria for safe storage. The purpose of this document is to demonstrate that within the defined operating conditions, the HBL process will be equivalent for meeting the requirements of the DOE-STD-3013 stabilization process for plutonium-bearing materials from the DOE complex. The proposed 3013 equivalency reduces the prescribed stabilization temperature for high-purity PuO{sub 2} from oxalate precipitation processes from 950 C to 640 C and places a limit of 60% on the relative humidity (RH) at the lowest material temperature. The equivalency is limited to material produced using the HBL established flow sheet, for example, nitric acid anion exchange and Pu(IV) direct strike oxalate precipitation with stabilization at a minimum temperature of 640 C for four hours (h). The product purity must meet the MFFF acceptance criteria of 23,600 {micro}g/g Pu (i.e., 2.1 wt %) total impurities and chloride content less than 250 {micro}g/g of Pu. All other stabilization and packaging criteria identified by DOE-STD-3013-2012 or earlier revisions of the standard apply. Based on the evaluation of test data discussed in this document, the expert judgment of the authors supports packaging ...
Date: July 2, 2012
Creator: Duffey, J.; Livingston, R.; Berg, J. & Veirs, D.
Partner: UNT Libraries Government Documents Department

STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS

Description: Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.
Date: May 1, 2009
Creator: Lam, P; Philip Zapp, P; Jonathan Duffey, J & Kerry Dunn, K
Partner: UNT Libraries Government Documents Department

Relative Humidity and the Susceptibility of Austenitic Stainless Steel to Stress Corrosion Cracking in an impure Plutonium Oxide Environment

Description: Laboratory tests to investigate the corrosivity of moist plutonium oxide/chloride salt mixtures on 304L and 316L stainless steel coupons showed that corrosion occurred in selected samples. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The exposures were conducted in sealed containers in which the oxide-salt mixtures were loaded with about 0.6 wt % water from a humidified helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration, the composition of the salt and the moisture present in the test environment. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride and 0.6 wt% water. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas above the solid mixture, or in coupons exposed to other mixtures with either no CaCl{sub 2} or 0.92 wt% CaCl{sub 2}. SCC was present where the 0.6 wt % water content exceeded the value needed to fully hydrate the available CaCl{sub 2}, but was absent where the water content was insufficient. These results reveal the significance of the relative humidity in the austenitic stainless steels environment to their susceptibility to corrosion. The relative humidity in the test environment was controlled ...
Date: May 5, 2010
Creator: Zapp, P.; Duffey, J.; Lam, P. & Dunn, K.
Partner: UNT Libraries Government Documents Department

LOCALIZED CORROSION OF AUSTENITIC STAINLESS STEELEXPOSED TO MIXTURES OF PLUTONIUM OXIDE AND CHLORIDE SALTS

Description: Laboratory corrosion tests were conducted to investigate the corrosivity of moist plutonium oxide/chloride (PuO{sub 2}/Cl-) salt mixtures on 304L and 316L stainless steel coupons. The tests exposed flat coupons for pitting evaluation and 'teardrop' stressed coupons for stress corrosion cracking (SCC) evaluation at room temperature to various mixtures of PuO{sub 2} and chloride-bearing salts for periods up to 500 days. The two flat coupons were placed so that the solid oxide/salt mixture contacted about one half of the coupon surface. One teardrop coupon was placed in contact with solid mixture; the second teardrop was in contact with the headspace gas only. The mixtures were loaded with nominally 0.5 wt % water under a helium atmosphere. Observations of corrosion ranged from superficial staining to pitting and SCC. The extent of corrosion depended on the total salt concentration and on the composition of the salt. The most significant corrosion was found in coupons that were exposed to 98 wt % PuO{sub 2}, 2 wt % chloride salt mixtures that contained calcium chloride. SCC was observed in two 304L stainless steel teardrop coupons exposed in solid contact to a mixture of 98 wt % PuO{sub 2}, 0.9 wt % NaCl, 0.9 wt % KCl, and 0.2 wt % CaCl{sub 2}. The cracking was associated with the heat-affected zone of an autogenous weld that ran across the center of the coupon. Cracking was not observed in coupons exposed to the headspace gas, nor in coupons exposed to other mixtures with either 0.92 wt% CaCl{sub 2} or no CaCl{sub 2}. The corrosion results point to the significance of the interaction between water loading and the concentration of the hydrating salt CaCl{sub 2} in the susceptibility of austenitic stainless steels to corrosion.
Date: November 21, 2008
Creator: Zapp, P; Kerry Dunn, K; Jonathan Duffey, J; Ron Livingston, R & Zane Nelson, Z
Partner: UNT Libraries Government Documents Department

DIRECT DISPOSAL OF A RADIOACTIVE ORGANIC WASTE IN A CEMENTITIOUS WASTE FORM

Description: The disposition of {sup 137}Cs-containing tetraphenylborate (TPB) waste at the Savannah River Site (SRS) by immobilization in the cementitious waste form, or grout called ''saltstone'' was proposed as a straightforward, cost-effective method for disposal. Tests were performed to determine benzene release due to TPB decomposition in saltstone at several initial TPB concentrations and temperatures. The benzene release rates for simulants and radioactive samples were generally comparable at the same conditions. Saltstone monoliths with only the top surface exposed to air at 25 and 55 C at any tetraphenylborate concentration or at any temperature with 30 mg/L TPB gave insignificant releases of benzene. At higher TPB concentrations and 75 and 95 C, the benzene release could result in exceeding the Lower Flammable Limit in the saltstone vaults.
Date: February 22, 2007
Creator: Zamecnik, J; Alex Cozzi, A; Russell Eibling, R; Jonathan Duffey, J & Kim Crapse, K
Partner: UNT Libraries Government Documents Department

GAS ANALYSES FROM HEADSPACE OF PLUTONIUM-BEARING MATERIALS CONTAINERS

Description: The Savannah River National Laboratory (SRNL) 3013 destructive examination program performs surveillances on 3013 containers originating from multiple sites across the DOE complex. The bases for the packaging, storage, and surveillance activities are derived from the Department of Energy's 3013 Standard (DOE-STD-3013-2004). During destructive examination, headspace gas samples are obtained from the 3013 inner container and the annulus between the outer and inner containers. To characterize gas species, the samples are analyzed by gas chromatography (GC), direct-inlet mass spectrometry (DIMS), and Fourier-transform infrared spectroscopy (FTIR). The GC results, as well as other parameters, are utilized as input into the gas evaluation software tool (GEST) program for computation of pre-puncture gas compositions and pressures. Over 30 containers from the Hanford Site and the Rocky Flats Environmental Technology Site (RFETS) have been examined in the first three years of the surveillance program. Several containers were shown to have appreciable hydrogen content (some greater than 30 mol %), yet little or no oxygen was detected in any of the containers, including those exhibiting high hydrogen concentrations. Characteristics including moisture content, surface area, and material composition, along with the headspace gas composition, are utilized in an attempt to explain the chemical behavior of the packaged materials.
Date: February 1, 2010
Creator: Almond, P.; Livingston, R.; Traver, L.; Arnold, M.; Bridges, N.; Kessinger, G. et al.
Partner: UNT Libraries Government Documents Department

MATERIAL PROPERTIES OF PLUTONIUM-BEARING OXIDES STORED IN STAINLESS STEEL CONTAINERS

Description: The destructive examination (DE) of 3013 containers after storage is part of the Surveillance and Monitoring Program based on the Department of Energy's standard for long-term storage of Pu (DOE-STD-3013). The stored, Pu-bearing materials may contain alkali halide contamination that varies from trace amounts of salt to about 50 weight percent, with smaller fractions of other compounds and oxides. These materials were characterized prior to packaging, and surveillance characterizations are conducted to determine the behavior of the materials during long term storage. The surveillance characterization results are generally in agreement with the pre-surveillance data. The predominant phases identified by X-ray diffraction are in agreement with the expected phase assemblages of the as-received materials. The measured densities are in reasonable agreement with the expected densities of materials containing the fraction of salts and actinide oxide specified by the pre-surveillance data. The radiochemical results are generally in good agreement with the pre-surveillance data for mixtures containing 'weapons grade' Pu (nominally 94% {sup 239}Pu and 6% {sup 240}Pu); however, the ICP-MS results from the present investigation generally produce lower concentrations of Pu than the pre-surveillance analyses. For mixtures containing 'fuel grade' Pu (nominally 81-93% {sup 239}Pu and 7-19% {sup 240}Pu), the ICP-MS results from the present investigation appear to be in better agreement with the pre-surveillance data than the radiochemistry results.
Date: February 1, 2010
Creator: Kessinger, G.; Almond, P.; Bridges, N.; Bronikowski, M.; Crowder, M.; Duffey, J. et al.
Partner: UNT Libraries Government Documents Department

Measurements of Flammable Gas Generation from Saltstone Containing Actual Tank 48H Waste (Interim Report)

Description: The Savannah River National Laboratory was tasked with determining the benzene release rates in saltstone prepared with tetraphenylborate (TPB) concentrations ranging from 30 mg/L to 3000 mg/L in the salt fraction and with test temperatures ranging from ambient to 95 C. Defense Waste Processing Facility Engineering (DWPF-E) provided a rate of benzene evolution from saltstone of 2.5 {micro}g/L/h saltstone (0.9 {micro}g/kg saltstone/h [1.5 {micro}g/kg saltstone/h x 60%]) to use as a Target Rate of Concern (TRC). The evolution of benzene, toluene, and xylenes from saltstone containing actual Tank 48H salt solution has been measured as a function of time at several temperatures and concentrations of TPB. The Tank 48H salt solution was aggregated with a DWPF recycle simulant to obtain the desired TPB concentrations in the saltstone slurry. The purpose of this interim report is to provide DWPF-E with an indication of the trends of benzene evolution. The data presented are preliminary; more data are being collected and may alter the preliminary results. A more complete description of the methods and materials will be included in the final report. The benzene evolution rates approximately follow an increasing trend with both increasing temperature and TPB concentration. The benzene release rates from 1000 mg/L TPB at 95 C and 3000 mg/L TPB at 75 C and 95 C exceeded the recovery-adjusted 0.9 mg/kg saltstone/h TRC (2.5 {micro}g/L saltstone/h), while all other conditions resulted in benzene release rates below this TRC. The toluene evolution rates for several samples exceeded the TRC initially, but all dropped below the TRC within 2-5 days. The toluene emissions appear to be mainly dependent on the fly ash and are independent of the TPB level, indicating that toluene is not generated from TPB.
Date: June 1, 2005
Creator: Cozzi, A. D.; Crowley, D. A.; Duffey, J. M.; Eibling, R. E.; Jones, T. M.; Marinik, A. R. et al.
Partner: UNT Libraries Government Documents Department