41 Matching Results

Search Results

Advanced search parameters have been applied.

Solidification of low-level radioactive waste at the Savannah River Site

Description: Aqueous-based process waste and other small volume wastes including basin sludge and incinerator ash will be solidified in cement-based wasteforms at SRS. A variety of inorganic solidifying agents are used depending on the chemistry, contaminants, and processing characteristics of the waste. In some cases, pre-treatment of the waste is used to reduce the activity of the waste and/or to remove the hazardous characteristics of the waste. In the case of DWPF saltstone, pretreatment is used to reduce 137 Cs and 90 Sr concentration to Class A levels and in-situ treatment (chemical reactions between the cementitious solids and waste) is used to remove the toxic metal characteristic of the waste. Chemical reduction of the Cr/sup +6/ to Cr/sup +3/ and subsequent precipitation of Cr(OH)/sub 3/, (low solubility) occurs as the result of reactions between the cementitious raw materials and the waste liquid. In summary waste treatment and solidification used at SRS is designed to meet both South Carolina and Federal requirements for maintaining the quality of the groundwater at the disposal site boundary. 2 refs.
Date: January 1, 1989
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Metal toxicity evaluation of Savannah River Plant saltstone comparison of EP and TCLP test results

Description: Saltstone is the waste treatment and disposal concept for low-level defense waste at the Savannah River Plant. The waste is a sodium salt solution which has about 230 ..mu..CiL in addition to the hazardous characteristics of corrosivity and metal toxicity (Cr/sup +6/ > 100 ppM). Two EPA test procedures are routinely used at SRP to evaluate metal toxicity of wastes and wasteforms. 1) the Extraction Procedure (EP); and 2) the Toxicity Characterization Leaching Procedure (TCLP). The EP test is required by SCDHEC and EPA. The TCLP is used to evaluate the effect of increased surface area on metal leaching from the various SRP wasteforms. EP and TCLP test results are presented for two types of wasteforms, a cement-based saltstone and for a slag-based saltstone. The slag saltstone chemically stabilizes and also physically entraps the chromium. For waste solutions with low to intermediate metal concentrations (up to 5000 ppM), the TCLP extracts typically have lower metal values than the EP extracts. This is attributed to the faster neutralization of the acetic acid by the crushed TCLP sample. Crushing increases surface area and consequently releases more alkalinity from the wasteform matrix and the wasteform pore solution. Metal concentrations in the EP and TCLP extracts are proportional to the concentrations of metals in the pore solution for both the cement or slag-based wasteforms. The pore solution concentrations for cement wasteforms are directly related to the soluble metal concentration in the waste. The metal concentration in the slag wasteform pore solutions are significantly lower than the waste because these metals are reduced lower valences and precipitated as insoluble solid phases. 3 refs., 3 figs., 5 tabs.
Date: January 1, 1988
Creator: Langton, C A
Partner: UNT Libraries Government Documents Department

Phosphate ceramic solidification and stabilization of cesium-containing crystalline silicotitanate resins.

Description: This paper reports on the fabrication and testing of magnesium potassium phosphate (MKP)-bonded cesium-loaded crystalline silicotitanate (CST) resins. Typical waste loading of CST resins in the final waste forms was 50 wt.%. Physical and chemical characterization of the MKP materials has shown them to be physically, chemically, and mineralogically stable. Long-term durability studies (using the AN 16.1 standard test) showed a leachability index of {approx}18 for cesium in the phosphate matrix when exposed to deionized water under ambient and elevated temperatures. Leaching of cesium was somewhat higher than in glass waste forms as per PCT and MCC-1 tests. MKP-based final waste forms showed no significant weight changes after exposure to aqueous media for {approx}90 days, indicating the highly insoluble nature of the phosphate matrix. In addition, durability of the CST-MKP waste forms was further established by freeze-thaw cycling tests.
Date: May 11, 1999
Creator: Langton, C. A.
Partner: UNT Libraries Government Documents Department

Direct Grout Stabilization of High Cesium Salt Waste: Salt Alternative Phase III Feasibility Study

Description: The direct grout alternative is a viable option for treatment/stabilization and disposal of salt waste containing Cs-137 concentrations of 1-3 Ci/gal. The composition of the direct grout salt solution is higher in sodium salts and contains up to a few hundred ppm Cs-137 more than the current reference salt solution. However it is still similar to the composition of the current reference salt solution. Consequently, the processing, setting, and leaching properties (including TCLP for Cr and Hg) of the direct grout and current saltstone waste forms are very similar. The significant difference between these waste solutions is that the high cesium salt solution will contain between 1 and 3 Curies of Cs-137 per gallon compared to a negligible amount in the current salt solution. This difference will require special engineering and shielding for a direct grout processing facility and disposal units to achieve acceptable radiation exposure conditions. The Cs-137 concentration in the direct grout salt solution will also affect the long-term curing temperature of the waste form since 4.84 Watts of energy are generated per 1000 Ci of Cs-137. The temperature rise of the direct grout during long-term curing has been calculated by A. Shaddy, SRTC.1 The effect of curing temperature on the strength, leaching and physical durability of the direct grout saltstone is described in this report. At the present time, long term curing at 90 degrees C appears to be unacceptable because of cracking which will affect the structural integrity as evaluated in the immersion test. (The experiments conducted in this feasibility study do not address the effect of cracking on leaching of contaminants other than Cr, Hg, and Cs.) No cracking of the direct grout or reference saltstone waste forms was observed for samples cured at 70 degrees C. At the present time the implications of waste ...
Date: December 7, 1998
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Bleed water testing program for controlled low strength material

Description: Bleed water measurements for two Controlled Low Strength Material (CLSM) mixes were conducted to provide engineering data for the Tank 20F closure activities. CLSM Mix 1 contained 150 pounds of cement per cubic yard whereas CLSM Mix 2 contained 50 pounds per cub yard. SRS currently used CLSM Mix 2 for various applications. Bleed water percentages and generation rates were measured along with flow and compressive strength. This information will be used to select a mix design for the Tank 20F closure activities and to establish the engineering requirements, such as, lift height, time required between lifts and quantity of bleed water to be removed from the tank during the placement activities. Mix 1 is recommended for placement within Tank 20F because it has better flow characteristics, less segregation, lower percentage of bleed water and slightly higher strength. Optimization of Mix 1 was beyond the scope of this study. However, further testing of thickening additives, such as clays (bentonite), sodium silicate or fine silicas maybe useful for decreasing or eliminating bleed water.
Date: November 12, 1996
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Geotechnical Analysis of Five Shelby Tube Samples from H-Area Retention Basin

Description: Geotechnical and geochemical analyses were performed on five Shelby tube samples collected in the H-Area Retention Basin (HRB) during July and August of 1998. The samples were collected as part of the HRB characterization study. The test results, which are documented in this report, will be used to support the HRB contaminant fate and transport modeling/analysis and to evaluate remedial options. The results will also be used as a base line for future treatability studies.
Date: June 2, 1999
Creator: Langton, C. A.
Partner: UNT Libraries Government Documents Department

Characterization of Fernald Silo 3 Waste

Description: This report summarizes characterization results for uranium residues from the Fernald Environmental Management Project (FEMP) Operable Unit (OU-4). These residues are currently stored in a one-million-gallon concrete silo, Silo 3, at the DOE Fernald Site, Ohio. Characterization of the Silo 3 waste is the first part of a three part study requested by Rocky Mountain Remedial Services (RMRS) through a Work for others Agreement, WFO-00-007, between the Westinghouse Savannah River Company (WSRC) and RMRS. Parts 2 and 3 of this effort include bench- and pilot-scale testing.
Date: April 4, 2001
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Silo 3 Waste Treatment Phase I Physical Testing Final Report

Description: A characterization study of the Fernald Silo 3 waste was performed at the request of Rocky Mountain Remedial Services, LLC (RMRS) to support treatment of the waste with the Envirobond reagents and Envirobrick process. The Savannah River Technology Center (SRTC) performed the characterization under a Work for Others Agreement WOF-00-007. Physical property testing was subcontracted to the Clemson Environmental Technologies Laboratory (CETL). This report is intended to transmit the results of the physical property testing conducted at the CETL. Results of the physical property testing are summarized in a final report from Steve Hoeffner, CETL.
Date: March 13, 2001
Creator: Langton, C. A.
Partner: UNT Libraries Government Documents Department

High Performance Zero-Bleed CLSM/Grout Mixes for High-Level Waste Tank Closures Strategic Research and Development - FY99 Report

Description: The overall objective of this program, SRD-99-08, was to design and test suitable materials, which can be used to close high-level waste tanks at SRS. Fill materials can be designed to perform several functions including chemical stabilization and/or physical encapsulation of incidental waste so that the potential for transport of contaminants into the environment is reduced. Also they are needed to physically stabilize the void volume in the tanks to prevent/minimize future subsidence and inadvertent intrusion. The intent of this work was to develop a zero-bleed soil CLSM (ZBS-CLSM) and a zero-bleed concrete mix (ZBC) which meet the unique placement and stabilization/encapsulation requirements for high-level waste tank closures. These mixes in addition to the zero-bleed CLSM mixes formulated for closure of Tanks 17-F and 20-F provide design engineers with a suite of options for specifying materials for future tank closures.
Date: August 11, 2000
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

High performance zero-bleed CLSM/grout mixes for high-level waste tank closures strategic research and development - FY98

Description: The overall objective of this program, SRD-98-08, is to design and test suitable materials, which can be used to close high-level waste tanks at the Savannah River Site. Fill materials can be designed to perform several functions. They can be designed to chemically stabilize and/or physically encapsulate incidental waste so that the potential for transport of contaminants into the environment is reduced. Also they are needed to physically stabilize the void volume in the tanks to prevent/minimize future subsidence and inadvertent intrusion.
Date: February 17, 2000
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Ceramicrete{trademark} Stabilization of CST Resin: ITP Alternative Phase III Feasibility Study

Description: The Ceramicrete{trademark} waste form is a magnesium phosphate hydrate, which sets as the result of an acid-base reaction between KH{sub 2}PO{sub 4} and MgO in the presence of water. Based on the results of this feasibility study, this low temperature ceramic waste form is acceptable for stabilization of cesium loaded crystalline silicotitanate (CST) resin. The performance objective of CST stabilization is to convert a friable powdered resin into a monolithic form to improve handling and storage and to reduce the waste mobility. Advantages of this type of the CST-Ceramicrete{trademark} waste form include: room temperature processing of a fluid slurry, limited off gas, flexible mix designs, rapid setting, no free liquids, temperature tolerant and durable up to at least 90 degrees C. The Ceramicrete/220 waste form can be processed by in-container mixing or by batch mixing. Since a trace amount of free water will be associated with the wet resin in the CST-Ceramicrete{trademark} waste form, radiolysis of the free water may cause pressurization of the containers. Leaching tests were conducted to evaluate the CST-Ceramicrete{trademark} waste form performance relative to high-level waste glass. Results were very encouraging given that only one waste loading (50 wt. percent resin) was tested and that the leaching procedures were not fully optimized for a non-glass waste form. In general, the cesium leachability per the PCT test of the CST-Ceramicrete{trademark} waste was about 2X more than that of the ARM glass and about 200X more than the EA glass. For monolithic samples (MCC-1 test), the CST-Ceramicrete{trademark} waste form leached 4X to7X more cesium than the ARM glass. (The EA glass is not suited to monolithic leaching.) The CST-Ceramicrete{trademark} leaching results appear to be independent of curing temperature over the range 24 to 90 degrees C.
Date: December 7, 1998
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Studies of ancient concrete as analogs of cementitious sealing materials for a repository in tuff

Description: The durability of ancient cementitious materials has been investigated to provide data applicable to determining the resistance to weathering of concrete materials for sealing a repository for storage of high-level radioactive waste. Because tuff and volcanic ash are used in the concretes in the vicinity of Rome, the results are especially applicable to a waste repository in tuff. Ancient mortars, plasters, and concretes collected from Rome, Ostia, and Cosa dating to the third century BC show remarkable durability. The aggregates used in the mortars, plasters, and concretes included basic volcanic and pyroclastic rocks (including tuff), terra-cotta, carbonates, sands, and volcanic ash. The matrices of ancient cementitious materials have been characterized and classified into four categories: (1) hydraulic hydrated lime and hydrated lime cements, (2) hydraulic aluminous and ferruginous hydrated lime cements ({plus_minus} siliceous components), (3) pozzolana/hydrated lime cements, and (4) gypsum cements. Most of the materials investigated are in category (3). The materials were characterized to elucidate aspects of the technology that produced them and their response to the environmental exposure throughout their centuries of existence. Their remarkable properties are the result of a combination of chemical, mineralogical, and microstructural factors. Their durability was found to be affected by the matrix mineralogy, particle size, and porosity; aggregate type, grading and proportioning; and the methodology of placement. 30 refs.
Date: March 1, 1989
Creator: Roy, D.M. & Langton, C.A.
Partner: UNT Libraries Government Documents Department

Direct Grout Stabilization of High Cesium Salt Waste: Cesium Leaching Studies

Description: 'The direct grout alternative is a viable option for treatment/stabilization and disposal of salt waste containing Cs-137 concentrations of 1-3 Ci/gal. The significant difference between these waste solutions is that the high cesium salt solution will contain between 1 and 3 Curies of Cs-137 per gallon compared to a negligible amount in the current salt solution. This difference will require special engineering and shielding for a direct grout processing facility and disposal units to achieve acceptable radiation exposure conditions. The higher cesium concentrations in the direct grout also require that the cesium leaching be evaluated as a function of curing temperature. ANS 16.1 leaching results and distribution ratios (approximations of distribution coefficients) as a function of temperature are presented in this report.'
Date: September 19, 1999
Creator: Langton, C. A.
Partner: UNT Libraries Government Documents Department

PUREX Organic Waste Solidification

Description: The objectives of this study were to evaluate solidification/stabilization as an alternative treatment technology for the organic phase of the SRS spent PUREX waste using simulated waste, and to evaluate waste forms prepared with actual spent organic PUREX waste for regulatory classification.
Date: December 12, 2002
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

PUREX Waste Stabilization

Description: This report summarizes the results of a feasibility study that evaluated solidification as an alternative treatment for organic waste.
Date: February 14, 2003
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Stabilization of Tank 33 and 35 Aqueous PUREX Waste

Description: Approximately 38,000 gallons of PUREX waste are currently stored in the New Solvent Storage Tanks (NSST), Tanks 33 and 35. The waste consists of both an organic and aqueous fraction. Solidification is currently being evaluated for the 24,800 gallons of organic PUREX waste.
Date: April 10, 2002
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Aqueous Zinc Bromide Waste Solidification

Description: The goal of this study was to select one or more commercially available aqueous sorbents to solidify the zinc bromide solution stored in C-Area, identify the polymer to zinc bromide solution ratio (waste loading) for the selected sorbents, and identify processing issues that require further testing in pilot-scale testing.
Date: July 23, 2002
Creator: Langton, C.A.
Partner: UNT Libraries Government Documents Department

Defense waste salt disposal at the Savannah River Plant. [Cement-based waste form, saltstone]

Description: A cement-based waste form, saltstone, has been designed for disposal of Savannah River Plant low-level radioactive salt waste. The disposal process includes emplacing the saltstone in engineered trenches above the water table but below grade at SRP. Design of the waste form and disposal system limits the concentration of salts and radionuclides in the groundwater so that EPA drinking water standards will not be exceeded at the perimeter of the disposal site. 10 references, 4 figures, 3 tables.
Date: January 1, 1984
Creator: Langton, C A & Dukes, M D
Partner: UNT Libraries Government Documents Department

Cast Stone Oxidation Front Evaluation: Preliminary Results For Samples Exposed To Moist Air

Description: The rate of oxidation is important to the long-term performance of reducing salt waste forms because the solubility of some contaminants, e.g., technetium, is a function of oxidation state. TcO{sub 4}{sup −} in the salt solution is reduced to Tc(IV) and has been shown to react with ingredients in the waste form to precipitate low solubility sulfide and/or oxide phases. Upon exposure to oxygen, the compounds containing Tc(IV) oxidize to the pertechnetate ion, Tc(VII)O{sub 4}{sup −}, which is very soluble. Consequently the rate of technetium oxidation front advancement into a monolith and the technetium leaching profile as a function of depth from an exposed surface are important to waste form performance and ground water concentration predictions. An approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) based on leaching of select contaminants of concern is described in this report. In addition, the relationship between reduction capacity and contaminant oxidation is addressed. Chromate (Cr(VI) was used as a non-radioactive surrogate for pertechnetate, Tc(VII), in Cast Stone samples prepared with 5 M Simulant. Cast Stone spiked with pertechnetate was also prepared and tested. Depth discrete subsamples spiked with Cr were cut from Cast Stone exposed to Savannah River Site (SRS) outdoor ambient temperature fluctuations and moist air. Depth discrete subsamples spiked with Tc-99 were cut from Cast Stone exposed to laboratory ambient temperature fluctuations and moist air. Similar conditions are expected to be encountered in the Cast Stone curing container. The leachability of Cr and Tc-99 and the reduction capacities, measured by the Angus-Glasser method, were determined for each subsample as a function of depth from the exposed surface. The results obtained to date were focused on continued method development and are preliminary and apply to the sample composition and curing / exposure conditions described in this report. The Cr ...
Date: November 26, 2013
Creator: Langton, C. A. & Almond, P. M.
Partner: UNT Libraries Government Documents Department

Tanks 18 And 19-F Structural Flowable Grout Fill Material Evaluation And Recommendations

Description: Cementitious grout will be used to close Tanks 18-F and 19-F. The functions of the grout are to: 1) physically stabilize the final landfill by filling the empty volume in the tanks with a non-compressible material; 2) provide a barrier for inadvertent intrusion into the tank; 3) reduce contaminant mobility by a) limiting the hydraulic conductivity of the closed tank and b) reducing contact between the residual waste and infiltrating water; and 4) providing an alkaline, chemically reducing environment in the closed tank to control speciation and solubility of selected radionuclides. The objective of this work was to identify a single (all-in-one) grout to stabilize and isolate the residual radionuclides in the tank, provide structural stability of the closed tank and serve as an inadvertent intruder barrier. This work was requested by V. A. Chander, High Level Waste (HLW) Tank Engineering, in HLW-TTR-2011-008. The complete task scope is provided in the Task Technical and QA Plan, SRNL-RP-2011-00587 Revision 0. The specific objectives of this task were to: 1) Identify new admixtures and dosages for formulating a zero bleed flowable tank fill material selected by HLW Tank Closure Project personnel based on earlier tank fill studies performed in 2007. The chemical admixtures used for adjusting the flow properties needed to be updated because the original admixture products are no longer available. Also, the sources of cement and fly ash have changed, and Portland cements currently available contain up to 5 wt. % limestone (calcium carbonate). 2) Prepare and evaluate the placement, compressive strength, and thermal properties of the selected formulation with new admixture dosages. 3) Identify opportunities for improving the mix selected by HLW Closure Project personnel and prepare and evaluate two potentially improved zero bleed flowable fill design concepts; one based on the reactor fill grout and the other based ...
Date: April 23, 2013
Creator: Langton, C. A. & Stefanko, D. B.
Partner: UNT Libraries Government Documents Department

CLSM bleed water reduction test results

Description: Previous testing by BSRI/SRTC/Raytheon indicated that the CLSM specified for the Tank 20 closure generates about 6 gallons (23 liters) of bleed water per cubic yard of material (0.76 m3).1 This amount to about 10 percent of the total mixing water. HLWE requested that the CLSM mix be optimized to reduce bleed water while maintaining flow. Elimination of bleed water from the CLSM mix specified for High-Level Waste Tank Closure will result in waste minimization, time savings and cost savings. Over thirty mixes were formulated and evaluated at the on-site Raytheon Test Laboratory. Improved low bleed water CLSM mixes were identified. Results are documented in this report.
Date: April 21, 1997
Creator: Langton, C.A. & Rajendran, N.
Partner: UNT Libraries Government Documents Department

High performance CLSM field mixing and pumping test results

Description: An improved low bleed water CLSM mix was field tested on May 13, 1997 at the Throop portable auger batching plant. Production and pumping tests were very successful. The four cubic yards of material pumped into a ply wood form where it flowed 48 feet (the entire length of the form). The CLSM slurry was very uniform, self leveling, cohesive, showed no segregation, and had no bleed water. Properties of the High Performance CLSM were the same for material collected at the auger and at the end of the pipeline except for the air content which was 5.5% at the auger and 3.2% at the end of the pipeline. This is exactly what was expected and indicates that this CLSM is easy to mix and pump in the Throop/BSRI equipment. CLSM Mix TW-10 is recommended for Tank Closure based on the field batching and pumping tests.
Date: May 14, 1997
Creator: Rajendran, N. & Langton, C.A.
Partner: UNT Libraries Government Documents Department