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DOE OSTI2010

PUBLIC AND REGULATORY ACCEPTANCE OF BLENDING OF RADIOACTIVE WASTE VS DILUTION

On April 21, 2009, the Energy Facilities Contractors Group (EFCOG) Waste Management Working Group (WMWG) provided a recommendation to the Department of Energy's Environmental Management program (DOE-EM) concerning supplemental guidance on blending methodologies to use to classify waste forms to determine if the waste form meets the definition of Transuranic (TRU) Waste or can be classified as Low-Level Waste (LLW). The guidance provides specific examples and methods to allow DOE and its Contractors to properly classify waste forms while reducing the generation of TRU wastes. TRU wastes are much more expensive to characterize at the generator's facilities, ship, and then dispose at the Waste Isolation Pilot Plant (WIPP) than Low-Level Radioactive Waste's disposal. Also the reduction of handling and packaging of LLW is inherently less hazardous to the nuclear workforce. Therefore, it is important to perform the characterization properly, but in a manner that minimizes the generation of TRU wastes if at all possible. In fact, the generation of additional volumes of radioactive wastes under the ARRA programs, this recommendation should improve the cost effective implementation of DOE requirements while properly protecting human health and the environment. This paper will describe how the message of appropriate, less expensive, less hazardous blending of radioactive waste is the 'right' thing to do in many cases, but can be confused with inappropriate 'dilution' that is frowned upon by regulators and stakeholders in the public. A proposal will be made in this paper on how to communicate this very complex and confusing technical issue to regulatory bodies and interested stakeholders to gain understanding and approval of the concept. The results of application of the proposed communication method and attempt to change the regulatory requirements in this area will be discussed including efforts by DOE and the NRC on this very complex subject.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2012

Recent Improvements In Interface Management For Hanfords Waste Treatment And Immobilization Plant - 13263

The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms operations and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities by 2047. The WTP is currently being designed and constructed by Bechtel National Inc. (BNI) for DOE-ORP. BNI relies on a number oftechnical services from other Hanford contractors for WTP's construction and commissioning. These same services will be required of the future WTP operations contractor. The WTP interface management process has recently been improved through changes in organization and technical issue management documented in an Interface Management Plan. Ten of the thirteen active WTP Interface Control Documents (ICDs) have been revised in 2012 using the improved process with the remaining three in progress. The value of the process improvements is reflected by the ability to issue these documents on schedule.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2017

Achieving Leak Tightness in New Savannah River Site Saltstone Disposal Units - 17454

Saltstone Disposal Unit (SDU) 6 is a new disposal unit at the Department of Energy's Savannah River Site Saltstone Disposal Facility. The Saltstone Facility is part of the site's overarching waste management and disposal system. It receives the low-level waste stream and will immobilize in grout more than 90 percent of the liquid volume generated during treatment of the site's liquid high level waste. SDU-6 is the first in a series of large disposal units to be constructed on site. Its internal diameter and height are 114 m (375 ft) and 13.1 m (43 ft), respectively. It uses a cylindrical wire-wrapped concrete water tank design (AWWA D110, Type I), and at 121 ML (32 Mgal), it is one of the largest structures of its kind in the country. Because of its size, SDU-6's base slab was placed in ten sections. Earlier placed sections restrained newer adjacent sections, resulting in shrinkage cracking. Visible cracks were repaired with epoxy. However, the SDU basemat leaked at less than an estimated 4 L/min rate during its first full-height hydrostatic test (2015). The project baseline was to install a coating system to chemically protect the concrete from the high-pH, high-sulfate Saltstone solutions. The coating was not installed during the first hydrostatic test, and subsequently, an adhered elastomeric liner system was chosen to provide higher assurance of bridging floor cracks and preventing leakage. A robust process was used to select and install a liner that will not only provide chemical protection but also achieve leak tightness, which was successfully demonstrated in a second hydrostatic test late in 2016. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Comparison of mass balance, energy consumption and cost of composting facilities for different types of organic waste

Mass balance, energy consumption and cost are basic pieces of information necessary for selecting a waste management technology. In this study, composting facilities that treat different types of organic waste were studied by questionnaire survey and via a chemical analysis of material collected at the facilities. The mass balance was calculated on a dry weight basis because the moisture content of organic waste was very high. Even though the ratio of bulking material to total input varied in the range 0-65% on a dry basis, the carbon and ash content, carbon/nitrogen ratio, heavy metal content and inorganic nutrients in the compost were clearly influenced by the different characteristics of the input waste. The use of bulking material was not correlated with ash or elemental content in the compost. The operating costs were categorised into two groups. There was some economy of scale for wages and maintenance cost, but the costs for electricity and fuel were proportional to the amount of waste. Differences in operating costs can be explained by differences in the process characteristics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

New AREVA's Investment in Continuous Improvement to Increase Efficiency of La Hague Reprocessing Lines - 18588

New AREVA currently operates 2 commercial reprocessing lines at their La Hague facility in France. Each line is capable of reprocessing up to 800 tHM/year of commercial spent light water reactor fuel. The site and process is self-contained with all waste arising from the reprocessing operations segregated into various waste streams and stabilized at the site. New AREVA operates a culture of continuous improvement and continues to invest in new technology, processes, waste management and procedures that have increased plant throughput while reducing waste volumes, operating cost while at the same time maintaining our strong safety culture. New investments have also been driven by changing customer needs and new markets. A good example of this has emerged over the last several years as New AREVA has been transporting a large amount of Research Reactor (RR) Uranium-Aluminum (UAl) type spent fuel (SF) on behalf of international RR operators to the La Hague site. Last year more than 100 RR fuel elements shipments were carried out by New AREVA (for fresh and spent fuel). In our current commercial lines the reprocessing of RRSF has been limited to approximately 1.4 ton a year. To meet increasing demand for reprocessing of RRSF, the range of RRSF that can now be reprocessed at La Hague has been extended to include Uranium-Aluminium-Silicium fuel (USi also called Silicide fuel) and also non-intact RRSF. In addition, New AREVA supported large scale research, development and engineering programs to identify processes/technology to allow the La Hague Facilities to reprocess a targeted average of additional 25 tons/year of non-commercial fuel types (RRSF and also fast reactor fuel, specific MOX fuel... ). A new facility head end called Traitement de Combustibles Particuliers (TCP) facility is currently planned to be implemented in the La Hague plant allowing reprocessed special fuels to be introduced into the existing commercial processing lines. The purpose of the paper is to demonstrate New AREVA's culture of continuous improvement that has been implemented at our commercial reprocessing facility highlighting how we have invested in processes and procedures for improving services to the nuclear operators. A case study will be presented related to our latest development of the TCP head end that will allow New AREVA to reprocess a targeted average of additional 25 tons/year of specialized fuels. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2015

Operating experience in the treatment and storage of LLW in Turkey - 15010

Treatment and storage of low-level radioactive wastes (LLW) are being carried out in Radioactive Waste Management Unit (RWMU) at Cekmece Nuclear Research and Training Center (CNRTC) in Istanbul. The wastes are generated from nuclear research and nuclear applications mainly in medicine, biology, ng to these specifications, LLW are classified as exempt waste, very low level waste (VLLW) etc. Decay storage is applied at a designated area for short lived radionuclide. Long lived spent radioactive sources are immobilized in retrievable packages. Generally liquid radioactive wastes are decontaminated by filtration or chemical precipitation. The radioactive sludge or filtration media from liquid waste processing is solidified using cementation. Solid waste is compacted into drums for size reduction. TENORM wastes and contaminated metal wastes are handled for decontamination and size reduction. Then these types of waste are placed in 20 ton bulk containers for long term storage. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Pixelated CZT Technology for the Detection, Identification, and Localization of Gamma-Ray Sources - 18311

Radioactive waste-management applications require good measurements to qualitatively and quantitatively characterize waste materials. Often these measurements must be done in situ, and the user wishes to learn something of the isotopic and spatial distribution of the source. Therefore, there is a need for a portable instrument that can map radioactive contamination and quantify sources. This presentation introduces several instruments that have been applied to this task, along with example measurements in relevant applications. All instruments are based on 3D-position-sensitive CdZnTe (CZT) detectors. This technology routinely achieves better than 1.1% FWHM energy resolution at 662 keV and operates at room temperature with a startup time under 2 minutes. All are packaged in portable enclosures with WiFi and Bluetooth capabilities for wireless communication. These capabilities allow the technology to be used in more advanced measurements in the field. A unique capability of these detectors is the ability to image the spatial distribution of gamma rays from a single stationary measurement. The first product, Polaris-H, has been in use at commercial nuclear power plants since 2013. The system, currently used at over 50% of the US nuclear-power fleet, integrates a 3D-position-sensitive CZT detector, associated readout electronics, an embedded computer, a battery with over 7-hour life, an optical camera, and a laser range finder in a portable water-proof enclosure. The system connects wirelessly to a tablet which displays a gamma-ray spectrum and isotope-specific images of the gamma-ray distribution in all directions in real time. The CZT detectors have a dynamic range from 50 keV up to 3 MeV. Coded aperture or pinhole imaging is used for energies below 250 keV, and Compton imaging is used for energies above 250 keV. List-mode data is saved to an external USB memory stick to enable more advanced analysis, including isotopic activity analysis, via H3D's post-processing software. Additional systems based on the same architecture have been developed to optimize the technology for other applications. These include Polaris-H Quad, which provides over 3 times the sensitivity for applications involving weaker sources, and Polaris-H Shield, which uses a collimator to provide images and isotope information over a narrower field of view in order to measure weaker sources in the presence of stronger sources of the same isotope. H3D has also developed custom systems that have been mounted on robots and drones that enable remote operation of the technology. Results from the measurements collected at commercial nuclear power plants and other applicable sites will be presented to show how these instruments can be used to detect, identify, and localize gamma-ray sources. Advanced analysis techniques to show the accurate quantification of the gamma-ray source will also be presented. Applications range from characterizing simple objects, to locating hottest points, estimating contamination distributions on an isotope-by-isotope basis, and differentiating scatter and direct emissions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2016

Benefits of a Full Waste Cost Recovery Program - 16322

A full waste cost recovery program has been established at the INL in order to fund disposition of all newly-generated hazardous, radioactive, and mixed waste at the INL. Significant improvements have resulted from implementation of this program at the INL, and it is anticipated that others could benefit from using a similar approach. The INL Waste Management Program (WMP) administers two site-wide service centers that collect revenue from programs and projects in order to pay waste disposition costs. These service centers are administered separately due to their unique scope and functions. The combination of these service centers provides the INL with a fully functional cost recovery program for all newly generated waste. This cost recovery program ensures that funding is available for disposition of all waste types and that waste costs are paid for by the generating programs or facilities. The implementation of these service centers in Fiscal Year 2014 has resulting in several significant improvements in waste disposition, including a substantial increase in awareness and emphasis on waste minimization and segregation. The service centers have virtually eliminated funding shortfalls from projects that end and have not budgeted for dispositioning waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2012

Proceedings of the 2012 International Congress on Advances in National Power Plants - ICAPP '12

ICAPP '12 provides a forum for leaders of the nuclear industry to exchange information, present results from their work, review the state of the industry, and discuss future directions and needs for the deployment of new nuclear power plant systems around the world. These proceedings gather 326 papers covering the following topics: 1. Water-Cooled Reactor Programs; 2. High Temperature Gas Cooled Reactors; 3. LMFR and Innovative Reactor Programs; 4. Operation, Performance and Reliability Management; 5. Plant Safety Assessment and Regulatory Issues; 6. Reactor Physics and Analysis; 7. Thermal Hydraulics Analysis and Testing; 8. Fuel Cycle and Waste Management; 9. Materials and Structural Issues; 10. Nuclear Energy and Global Environment; 11. Deployment and Cross-Cutting Issues; 12. Plant Licensing and International Regulatory Issues.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2011

SALTSTONE 4QCY10 TCLP RESULTS

Saltstone waste form was prepared in the Savannah River National Laboratory (SRNL) from a Tank 50H sample and Z-Area premix material for the fourth quarter of calendar year 2010 (4QCY10). After the prescribed 28 day cure, samples of the saltstone were collected, and the waste form was shown to meet the South Carolina Hazardous Waste Management Regulations (SCHWMR) R.61-79.261.24 and R.61-79.268.48(a) requirements for a nonhazardous waste form with respect to RCRA metals and underlying hazardous constituents. These analyses met all quality assurance specifications of USEPA SW-846.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

The role of intergenerational influence in waste education programmes: The THAW project

Highlights: > Children can be effective advocates in changing their parents' lifestyles. > We investigated the role of intergenerational influence in waste education programmes. > Waste Watch's Take Home Action on Waste project worked with 6705 children in 39 schools. > The results showed increased participation in recycling and declines in residual waste. > The study shows that recycling behaviour is positively impacted by intergenerational influence. - Abstract: Whilst the education of young people is often seen as a part of the solution to current environmental problems seeking urgent attention, it is often forgotten that their parents and other household members can also be educated/influenced via home-based educational activities. This paper explores the theory of intergenerational influence in relation to school based waste education. Waste Watch, a UK-based environmental charity ((www.wastewatch.org.uk)), has pioneered a model that uses practical activities and whole school involvement to promote school based action on waste. This methodology has been adopted nationally. This paper outlines and evaluates how effective school based waste education is in promoting action at a household level. The paper outlines Waste Watch's 'Taking Home Action on Waste (THAW)' project carried out for two and half years in Rotherham, a town in South Yorkshire, England. The project worked with 6705 primary age children in 39 schools (44% of primary schools in the project area) to enable them to take the 'reduce, reuse and recycle message' home to their families and to engage these (i.e. families) in sustainable waste management practices. As well as substantial increases in students' knowledge and understanding of waste reduction, measurement of the impact of the project in areas around 12 carefully chosen sample schools showed evidence of increased participation in recycling and recycling tonnages as well as declining levels of residual waste. Following delivery of the project in these areas, an average increase of 8.6% was recorded in recycling set out rates which led to a 4.3% increase in paper recycling tonnages and an 8.7% increase in tonnages of cans, glass and textiles collected for recycling. Correspondingly, there was a 4.5% fall in tonnages of residual waste. Waste Watch's THAW project was the first serious attempt to measure the intergenerational influence of an education programme on behaviour at home (i.e. other than schools' own waste). It clearly shows that household recycling behaviour can be positively impacted by intergenerational influence via a practical school-based waste education model. However, although the model could potentially have a big impact if rolled out nationally, it will require seed funding and the long-term durability of the model has not yet been fully quantified.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2016

Secondary Waste Form Development and Data Package for Hanford's Integrated Disposal Facility Performance Assessment - 16479

The Hanford Low-Activity Waste (LAW) Vitrification facility is planned to immobilize Hanford tank waste for on-site, near-surface disposal at Hanford's Integrated Disposal Facility (IDF). During this process, liquid and solid secondary wastes will be generated which are also slated for disposal at the IDF. In order to receive authorization to dispose of the waste in the IDF, a Performance Assessment (PA) must be completed in accordance with DOE Order 435.1, Radioactive Waste Management, and its accompanying Manual. The PA must include calculations of potential doses to a member of the public for a 1,000-year period to provide a reasonable expectation that performance objectives will not be exceeded and that the waste will be managed in a manner that is protective of worker and public health and safety, and the environment. Liquid and solid secondary wastes are planned to be immobilized within cementitious waste forms similar to those used elsewhere in the United States and around the world for permanent disposal of low-level radioactive waste (LLW). Data packages and supporting documents are being developed to provide the technical underpinning for the analyses of contaminant releases to the environment from these waste forms for the IDF PA. Traditionally, releases from cementitious waste forms have utilized a diffusion-limited release model using contaminant-specific diffusivities measured in standard leach tests as inputs. More mechanistic modeling techniques are under development to increase the rigor of the PA analyses. In addition, recent testing has shown diffusivities of key contaminants can be reduced by several orders-of-magnitude through optimized formulation of the waste form and use of additives to bind specific contaminants. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Attitude towards littering as a mediator of the relationship between personality attributes and responsible environmental behavior

Highlights: > Independently, altruism and locus of control contributed significantly toward attitude towards littering. > Altruism and locus of control jointly contributed significantly to attitude towards littering. > The results further show a significant joint influence of altruism and locus of control on REB. > The independent contributions reveal that altruism and locus of control contribute significantly to REB. > Attitude towards littering mediates the relationship between locus of control and REB. - Abstract: The study tested whether attitude towards littering mediates the relationship between personality attributes (altruism and locus of control) and responsible environmental behavior (REB) among some residents of Ibadan metropolis, Nigeria. Using multistage sampling technique, measures of each construct were administered to 1360 participants. Results reveal significant independent and joint influence of personality attributes on attitude towards littering and responsible environmental behavior, respectively. Attitude towards littering also mediates the relationship between personality characteristics and REB. These findings imply that individuals who possess certain desirable personality characteristics and who have unfavorable attitude towards littering have more tendencies to engage in pro-environmental behavior. Therefore, stakeholders who have waste management as their priority should incorporate this information when guidelines for public education and litter prevention programs are being developed. It is suggested that psychologists should be involved in designing of litter prevention strategies. This will ensure the inclusion of behavioral issues in such strategies. An integrated approach to litter prevention that combines empowerment, cognitive, social, and technical solutions is recommended as the most effective tool of tackling the litter problem among residents of Ibadan metropolis.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2017

Building the Future Nuclear Workforce Through Regional Partnerships - 17219

Industries across the United States of America are competing for highly skilled talent at a time when worker retirements are increasing and fewer students are pursuing science, technology, engineering and math (STEM) related fields of study. This specialized workforce is necessary for many industries, and it is essential for the processing and management of nuclear materials and operations of the nuclear security enterprise. Competition for STEM talent impacts the region that includes the Savannah River Site (SRS), a Department of Energy complex that is responsible for environmental stewardship, environmental cleanup, waste management and disposition of nuclear materials. SRS employs nearly 11,000 people and anticipates significant workforce attrition due to retirements over the next several years. In the SRS region, nuclear industry workers are also needed for the growing nuclear power industry as construction of four new nuclear power plants is taking place within an 80-mile radius of SRS. To address growing nuclear workforce needs in this region of Georgia and South Carolina, the SRS Community Reuse Organization (SRSCRO) established the Nuclear Workforce Initiative (NWI{sup R}) during 2009. Through NWI{sup R}, the SRSCRO has developed a network of partnerships with nuclear employers and regional educators to expand nuclear workforce development capabilities. Most notably, through NWI{sup R}, the SRSCRO established a partnership with five local colleges and universities and the Department of Energy Office of Environmental Management. Together, they have produced significant results. Recently, the National Nuclear Security Administration joined the partnership to help build the future nuclear workforce that includes scientists and engineers, but also skilled technicians, production operators, welders, nuclear quality specialists and other highly skilled professionals prepared to work in a secure and procedure-oriented environment. This paper highlights results from a successful partnership between a non-profit organization, academic institutions and the United States Department of Energy designed to expand the nuclear industry talent pool. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Overview of Kinectrics' Experience in Characterization of Low and Intermediate Level Waste (L and ILW) - 19144

Kinectrics has over two decades of experience in physico-chemical and radiological characterization of L and ILW generated from the operation and refurbishment of nuclear reactors owned by Ontario Power Generation (OPG). This characterization is required to develop an inventory and also to support the safety case, as well as licensing, of OPG's waste management facilities including its planned Deep Geological Repository (DGR) for Low and Intermediate Level Waste (L and ILW). The typical waste matrices characterized include reactor artefacts, non-processable, compactable, incinerable, ash, assorted resin, filters, and sludge. The objective of this paper is to present an overview of the characterization work undertaken over the years and further elaborate on some recent activities pertaining to characterization of a select subset of L and ILW streams such as pressure tubes, feeder pipes, bulk non-processable and active liquid waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

How an integrated change programme has accelerated the reduction in high hazard nuclear facilities at Sellafield

For over five decades the Sellafield Site has been central to the UK's nuclear programme. Now operated by Sellafield Ltd, under the management of Parent Body Organisation Nuclear Management Partners (NMP), a consortium of URS Washington Division, AMEC and AREVA is focussed on the decommissioning of historical facilities. When Decommissioning commenced in the late 1980's the site focus at that time was on commercial reprocessing and waste management. Now through the implementation of a company change programme, emphasis has shifted towards accelerated risk and hazard reduction of degraded legacy plants with nuclear inventory whilst ensuring value for money for the customer, the Nuclear Decommissioning Authority. This paper will describe the management success by the Site owners in delivering a successful change programme. The paper will explain how the site has transitioned to the INPO Standard Nuclear Performance Model (SNPM) and how through the use of a change maturity matrix has contributed to the accelerated reduction in high risk high hazard nuclear facilities. The paper will explain in detail how the Decommissioning Programme Office has facilitated and coordinated the Governance and assured delivery of the change plan and how successful application of visual management has aided the communication of its progress. Finally, the paper will discuss how the Delivery Schedules have proved critical for presenting the change plan to Key Stakeholders, Government Owners and Powerful Regulators. Overall, this paper provides an insight into how a massive change programme is being managed within one of the world's highest regulated industries. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Experimental Determination of the Speciation, Partitioning, and Release of Perrhenate as a Chemical Surrogate for Pertechnetate from a Sodalite-Bearing Multiphase Ceramic Waste Form

A key component to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. Multiphase ceramic waste forms have been studied extensively as a potential host matrix for nuclear waste. Understanding the speciation, partitioning, and release behavior of radionuclides immobilized in multiphase ceramic waste forms is a critical aspect of developing the scientific and technical basis for nuclear waste management. In this study, we evaluated a sodalite-bearing multiphase ceramic waste form (i.e., fluidized-bed steam reform sodium aluminosilicate [FBSR NAS] product) as a potential host matrix for long-lived radionuclides, such as technetium (99Tc). The FBSR NAS material consists primarily of nepheline (ideally NaAlSiO4), anion-bearing sodalites (ideally M8[Al6Si6O24]X2, where M refers to alkali and alkaline earth cations and X refers to monovalent anions), and nosean (ideally Na8[AlSiO4]6SO4). Bulk x-ray absorption fine structure analysis of the multiphase ceramic waste form, suggest rhenium (Re) is in the Re(VII) oxidation state and has partitioned to a Re-bearing sodalite phase (most likely a perrhenate sodalite Na8[Al6Si6O24](ReO4)2). Rhenium was added as a chemical surrogate for 99Tc during the FBSR NAS synthesis process. The weathering behavior of the FBSR NAS material was evaluated under hydraulically unsaturated conditions with deionized water at 90 C. The steady-state Al, Na, and Si concentrations suggests the weathering mechanisms are consistent with what has been observed for other aluminosilicate minerals and include a combination of ion exchange, network hydrolysis, and the formation of an enriched-silica surface layer or phase. The steady-state S and Re concentrations are within an order of magnitude of the nosean and perrhenate sodalite solubility, respectively. The order of magnitude difference between the observed and predicted concentration for Re and S may be associated with the fact that the anion-bearing sodalites contained in the multiphase ceramic matrix are present as mixed-anion sodalite phases. These results suggest the multiphase FBSR NAS material may be a viable host matrix for long-lived, highly mobilie radionuclides which is a critical aspect in the management of nuclear waste.

Pierce, Eric M↗

DOE OSTI2013

Experimental determination of the speciation, partitioning, and release of perrhenate as a chemical surrogate for pertechnetate from a sodalite-bearing multiphase ceramic waste form

A key component to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. Multiphase ceramic waste forms have been studied extensively as a potential host matrix for nuclear waste. Understanding the speciation, partitioning, and release behavior of radionuclides immobilized in multiphase ceramic waste forms is a critical aspect of developing the scientific and technical basis for nuclear waste management. In this study, we evaluated a sodalite-bearing multiphase ceramic waste form (i.e., fluidized-bed steam reform sodium aluminosilicate [FBSR NAS] product) as a potential host matrix for long-lived radionuclides, such as technetium (99Tc). The FBSR NAS material consists primarily of nepheline (ideally NaAlSiO4), anion-bearing sodalites (ideally M8[Al6Si6O24]X2, where M refers to alkali and alkaline earth cations and X refers to monovalent anions), and nosean (ideally Na8[AlSiO4]6SO4). Bulk X-ray absorption fine structure analysis of the multiphase ceramic waste form, suggest rhenium (Re) is in the Re(VII) oxidation state and has partitioned to a Re-bearing sodalite phase (most likely a perrhenate sodalite Na8[Al6Si6O24](ReO4)2). Rhenium was added as a chemical surrogate for 99Tc during the FBSR NAS synthesis process. The weathering behavior of the FBSR NAS material was evaluated under hydraulically unsaturated conditions with deionized water at 90 ?C. The steady-state Al, Na, and Si concentrations suggests the weathering mechanisms are consistent with what has been observed for other aluminosilicate minerals and include a combination of ion exchange, network hydrolysis, and the formation of an enriched-silica surface layer or phase. The steady-state S and Re concentrations are within an order of magnitude of the nosean and perrhenate sodalite solubility, respectively. The order of magnitude difference between the observed and predicted concentration for Re and S may be associated with the fact that the anion-bearing sodalites contained in the multiphase ceramic matrix are present as mixed-anion sodalite phases. These results suggest the multiphase FBSR NAS material may be a viable host matrix for long-lived, highly mobilie radionuclides which is a critical aspect in the management of nuclear waste.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗