Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine

Jb, Duncan; GA, COOKE; LL, LOCKREM

doi:10.2172/960294

Cited by 7 publications

(14 citation statements)

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“…A third detailed campaign to study Tc getters was performed by Duncan et al (2009) wherein a Basin 43 waste brine simulant (see Table 2.5, which represents contaminated Hanford groundwater concentrated by evaporation) was stabilized with a variant Cast Stone recipe that contained only Portland cement and the BFS at a 2:1 ratio. The two-component, Cast Stone dry blend was fortified by adding various Tc getters such that the final Cast Stone consisted of one part Basin 43 brine simulant to one part dry blend mix (consisting of the 2:1 Portland cement: BFS dry ingredients fortified with small masses of getters/reductants).…”

Section: 41mentioning

confidence: 99%

“…The cost of 2.15 SECAR 51 and the observation that its use leads to greater evolution of ammonia gas and waste form cracking late in the curing/hydration process were reasons that a switch to lime was made in the work conducted in 2006. A third waste simulant used by Cooke et al (2006cCooke et al ( , 2008 and Duncan et al (2009) was a salt concentrate from the evaporation of contaminated groundwater referred as Brine 43. The simulant composition is shown in Table 2.5.…”

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

“…The Duncan et al (2009) Tc-getter studies using organic-based ion exchange resins were effective in the short tests but raise the concern that the Purolite A 530-E and A 632-E might degrade and lose their anion retention properties over thousands of years. It was found that phosphate-based getters themselves were not effective at reducing the leachability of iodide or 99 Tc and in fact may have a detrimental impact on 99 Tc leachability.…”

Section: Impact Of Gettersmentioning

confidence: 99%

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Data Package for Secondary Waste Form Down-Selection—Cast Stone

Serne¹,

Westsik²

2011

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Executive SummaryThe objective of the data packages being generated for four potential waste forms for solidification/ stabilization of Hanford liquid secondary waste streams is to identify, evaluate, and summarize the existing information. This Cast Stone data package includes information available in the open literature and from data obtained from testing currently underway at Pacific Northwest National Laboratory (PNNL). As used at Hanford, the term Cast Stone describes a "grout"-based waste form made predominantly with fly ash and blast furnace slag (BFS) with lesser amounts of Portland cement as the starting dry blend. At Savannah River, this waste form is called Saltstone. The blend of grout reagents in Saltstone has been constant (45 weight percent [wt%] Grade 100 slag cement, 45 wt% Class F fly ash, and 10-wt% Type I/II Portland cement) since the Saltstone Disposal Facility began production in the early 1990s. At Hanford, some cementitious variants to Cast Stone have also been investigated, in which either the fly ash or the BFS is absent or replaced with another material. In this data package, these Cast Stone variants are included for completeness in the review. However, almost all the current Cast Stone waste form testing performed at PNNL uses a dry blend consisting of 47-wt% blast furnace slag (Grade 100), 45-wt% fly ash (Class F), and 8-wt% Portland cement (Type I/II). The sources of the three dry blend ingredients used at Hanford and Savannah River differ and may have subtle impacts on the physical and chemical attributes of the subsequent waste forms. The compositions of the secondary waste simulants used for the PNNL Cast Stone studies also differ from the simulants and actual wastes solidified at Savannah River; although both are caustic-, saline-and sodium-dominated solutions. The Hanford secondary waste simulants anion composition contains much less nitrate/nitrite than the waste streams solidified at Savannah River.Available literature on Cast Stone and Saltstone was reviewed with an emphasis on determining how Cast Stone and related grout waste forms performed in relationship to various criteria that will be used to decide whether a specific type of waste form meets acceptance criteria for disposal in the Integrated Disposal Facility (IDF) at Hanford. The draft waste acceptance criteria include the following requirements or targets:• acceptable leachate concentrations (less than the Universal Treatment Standards in 40 CFR 268) for Resource Conservation and Recovery Act (RCRA) metals using the Toxicity Characteristic Leach Procedure (TCLP) leach test• low bleed water criteria (i.e., no bleed water is tolerated after 28 days of curing)• low leachability index (LI) values for sodium (LI>6), technetium-99 (target LI>9) and iodine-129 (target LI>11)• minimum compressive strength of 500 psi (3.45 MPa).Other attributes of the Cast Stone process were compared with additional criteria, such as:• worker and public safety concerns• cost effectiveness versus other candidate waste forms in regard to ...

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Section: 41mentioning

confidence: 99%

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

Section: Impact Of Gettersmentioning

confidence: 99%

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Data Package for Secondary Waste Form Down-Selection—Cast Stone

Serne¹,

Westsik²

2011

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“…The Cast Stone (Figure 2.1) waste form was developed at the CH2M Hill Hanford Group Inc. to solidify numerous waste streams, including secondary waste generated at the Hanford Site (Lockrem 2005b, Cooke et al 2006a, 2006c, 2006dDuncan et al 2009, Duncan and Burke 2008, Cooke et al 2007). …”

Section: Containerized Cast Stonementioning

confidence: 99%

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

Pierce¹,

Mattigod²,

Westsik³

et al. 2010

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Executive SummaryPacific Northwest National Laboratory has initiated a waste-form testing program to support the longterm durability evaluation of a waste form for secondary wastes generated from the treatment and immobilization of Hanford radioactive tank wastes. The purpose of the work discussed in this report is to identify candidate stabilization technologies and getters that have the potential to successfully treat the secondary waste stream liquid effluent, mainly from off-gas scrubbers and spent solids, produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Down-selection to the most promising stabilization processes/waste forms is needed to support the design of a solidification treatment unit (STU) to be added to the Effluent Treatment Facility (ETF). To support key decision processes, an initial screening of the secondary liquid waste forms must be completed by February 2010. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary waste-form selection, development, and performance evaluation roadmap. The resulting waste form will be compliant to regulations and performance criteria and will lead to cost-effective disposal of the secondary wastes.This report starts with a brief review of some of the most commonly used solidification formulations that would be candidates for secondary liquid waste streams. In this review, the available data on performance are discussed, and some preliminary recommendations are provided for materials that should undergo additional screening testing. We also 1) discuss options for disposal of WTP secondary solid waste streams, 2) provide a brief overview of standard regulatory test methods used for measuring contaminant leachability and waste-form physical strength (with emphasis on the U.S. Environmental Protection Agency's [EPA's] new methods as a screening tool for comparing waste solidification materials of interest), and 3) provide an overview of factors that must be considered in long-term performance testing, including state-of-the-art characterization tools that can provide the data needed to technically defend predictive modeling simulations of long-term material behavior. The long-term wasteform testing and solid and leachate characterization must be robust enough to effectively predict material performance in the Integrated Disposal Facility over the 10,000-year period of performance for the engineered system. The solidification technologies for liquid waste streams include cement/grout, containerized Cast Stone, phosphate-bonded ceramics, alkali-aluminosilicate geopolymers, hydroceramics, L-TEM, and fluidized-bed steam reforming (FBSR). In addition to these, other mature technologies and two compounds, namely goethite and sodalite (that are still being developed), that show considerable promise as waste forms or getters are also discussed. It is our recommendation, based upon the available literature, that Cast Stone, chemically bonded phosphate ceramics (Ceramicrete...

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“…[11] One material that has shown potential for Tc removal in simulated groundwater is tin (II) apatite (Sn-A), ideally Sn5(PO4)3(F,Cl,OH). [14,15] The reductive capability of Sn-A arises from the presence of Sn(II), which has a favourable reduction potential for Sn(IV)/Sn(II) of 0.384 V [16] and can reduce Tc(VII) to Tc(IV). The Tc(VII)/Tc(IV) standard reduction potential is 0.738 V. [15] The reduction of TcO4by Sn(II) has been used in chemical syntheses in pharmaceutical development.…”

Section: Introductionmentioning

confidence: 99%

The function of Sn(II)-apatite as a Tc immobilizing agent

Asmussen

Neeway

Lawter

et al. 2016

Journal of Nuclear Materials

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At the U.S. Department of Energy Hanford Site, Tc-99 is a component of lowactivity waste (LAW) fractions of the nuclear tank waste and removal of Tc from LAW streams would greatly benefit the site remediation process. In this study, we investigated the removal of Tc(VII), as pertechnetate, from deionized water (DIW) and a LAW simulant through batch sorption testing and solid phase characterization using tin (II) apatite (Sn-A) and SnCl2. Sn-A showed higher levels of Tc removal from both DIW and LAW simulant. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/XEDS) and X-ray absorption spectroscopy (XAS) of reacted Sn-A in DIW showed that TcO4-is reduced to Tc(IV) on the Sn-A surface. The performance of Sn-A in the LAW simulant was lowered due to a combined effect of the high alkalinity, which lead to an increased dissolution of Sn from the Sn-A, and a preference for the reduction of Cr(VI).

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Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine

Cited by 7 publications

References 0 publications

Data Package for Secondary Waste Form Down-Selection—Cast Stone

Data Package for Secondary Waste Form Down-Selection—Cast Stone

Review of Potential Candidate Stabilization Technologies for Liquid and Solid Secondary Waste Streams

The function of Sn(II)-apatite as a Tc immobilizing agent

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