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All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

US DOE Perspectives on Advisory Board Effectiveness - 13539

Federal missions on the Oak Ridge Reservation began with the Manhattan Project, and continues today with major facilities supporting the Nation's Science and National Security missions. While most of the land area on the Oak Ridge Reservation is free of environmental impacts from these activities, significant legacy contamination is associated with specific facilities and past waste management areas. In 1989, the Oak Ridge Reservation (ORR) was placed on National Priorities List, and DOE established its Office of Environmental Management that same year. Three years later, in 1992, the Federal Facility Agreement for the reservation was signed. Three years afterward, the Oak Ridge Site Specific Advisory Board was established to augment ongoing public involvement activities related to Oak Ridge Reservation cleanup activities. One of the early and most impactful decisions the board made was to organize the End Use Working Group. This broad-based group of board members, DOE representatives, and members of the public was formed in 1997 to study future uses for contaminated areas of the reservation. The group was instrumental in building consensus in the Oak Ridge community regarding the long-term end state of reservation lands. The group's recommendations were a fundamental input into Record's of Decision subsequently developed to establish cleanup requirements across the ORR, and they continue to influence decisions being made today. In developing its recommendations on end states, the End Use Working Group came to the realization that long-term stewardship of contaminated areas of the reservation would be necessary, in some cases in perpetuity. It was from this concept that the Oak Ridge SSAB's 15-year involvement in stewardship would begin. A stewardship committee formed by the End Use Working Group wrote Volume 1 of the Stakeholder Report on Stewardship. This document-and its companion Volume 2, which was written a year later-form a crucial foundation for stewardship planning in Oak Ridge and have been referenced around the DOE complex as other sites consider stewardship planning. From these two broad-based initiatives, the board's focus has evolved to increasingly hone in on more specific, project-based recommendations and initiatives. The Oak Ridge Reservation Site Specific Advisory Board has been a highly effective forum for soliciting community input on Oak Ridge Reservation cleanup. Experience in Oak Ridge indicates that the utility of Board recommendations is far higher when the Board is asked to focus on broad programmatic issues, and less useful when the Board attempts to provide advice and recommendations on matters related to technical or project management issues. In Oak Ridge the Board has helped shape the program on many levels including definition of end-state cleanup objectives, budget development, program sequencing, waste management, and decisions concerning preservation of history related to missions implemented on the Oak Ridge Reservation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Life Cycle Costing in Radioactive Waste Packaging: Reducing Costs Whilst Accelerating Clean-Up - 16131

In recognition of the high up-front costs and potentially long timescales to implement the more traditional methods of encapsulating wastes, in the UK alternative approaches to help accelerate hazard reduction and reduce such costs are being deployed. When considering such the cost of alternative approaches to waste packaging strategies, it is important that the complete waste life cycle is taken into account. This paper will demonstrate that when evaluating waste packaging options, whilst individual elements (e.g. container costs) within an overall waste management programme may appear to offer a cost benefit by comparison with alternatives, the programme as a whole may not necessarily be the most cost effective solution when life cycle costs are taken into account, or when other technical issues are considered. To illustrate this point this paper will present a view of the application of LCC, utilising a number of waste packaging scenarios, to promote discussion and consideration of the benefits of undertaking a holistic assessment of the investment decision as part of an overall waste management strategy. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

The challenge: Safe management on spent and disused sealed radioactive source in Thailand - 15654

When sealed radioactive sources are no longer in use, they should be returned back to the country of origin. However, most of them could not be returned to the country of origin, therefore the safety management of spent and disused radioactive source is need. Thailand Institute of Nuclear Technology (TINT) where is as the national waste management center, has the duty to ensure on the safety and the security for long term storage of spent and disused sealed sources before final disposal. The Radioactive Waste Management Center at TINT, is authorized to operate treatment, conditioning and storage of radioactive waste. This paper will describe the proper operational procedures on characterization technique, identification of unknown sources, volume reduction technique, re-packaging, registration and record keeping of spent and disused radioactive source. The successful results exhibit that the record keeping of spent and disused source is developed, and the national inventory of spent and disused source is up to date. This paper would confirm the safety management of radioactive waste in Thailand. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Marine litter from beach-based sources: Case study of an Eastern Mediterranean coastal town

Highlights: • This paper reports and analyzes survey data for those interested in marine litter. • Bathing beach activities must be a high priority as a point of intervention. • Beach-goers must be encouraged to take an active role in keeping beaches clean. •Plastic fragments should be targeted as a first priority for prevention (& cleanup). • Non-plastic litter varies greatly from place to place along Mediterranean shores. - Abstract: Marine litter has been a serious and growing problem for some decades now. Yet, there is still much speculation among researchers, policy makers and planners about how to tackle marine litter from land-based sources. This paper provides insights into approaches for managing marine litter by reporting and analyzing survey results of litter dispersal and makeup from three areas along an Arab-Israeli coastal town in view of other recent studies conducted around the Mediterranean Sea. Based on our results and analysis, we posit that bathing beach activities should be a high priority for waste managers as a point of intervention and beach-goers must be encouraged to take a more active role in keeping beaches clean. Further, plastic fragments on the beach should be targeted as a first priority for prevention (and cleanup) of marine litter with plastic bottle caps being a high priority to be targeted among plastics. More survey research is needed on non-plastic litter composition for which amounts and geographic dispersal in the region vary greatly from place to place along Mediterranean shores. In general, findings of this study lead us to recommend exploring persuasive beach trash can design coupled with greater enforcement for short term waste management intervention while considering the local socio-economic and institutional context further for long-term efforts.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Integrated gasification and plasma cleaning for waste treatment: A life cycle perspective

Highlights: • A life cycle assessment of an advanced two-stage process is undertaken. • A comparison of the impacts of the process when fed with 7 feedstock is presented. • Sensitivity analysis on the system is performed. • The treatment of RDF shows the lowest impact in terms of both GWP and AP. • The plasma shows a small contribution to the overall impact of the plant. - Abstract: In the past, almost all residual municipal waste in the UK was landfilled without treatment. Recent European waste management directives have promoted the uptake of more sustainable treatment technologies, especially for biodegradable waste. Local authorities have started considering other options for dealing with residual waste. In this study, a life cycle assessment of a future 20 MWe plant using an advanced two-stage gasification and plasma technology is undertaken. This plant can thermally treat waste feedstocks with different composition and heating value to produce electricity, steam and a vitrified product. The objective of the study is to analyse the environmental impacts of the process when fed with seven different feedstocks (including municipal solid waste, solid refuse fuel, reuse-derived fuel, wood biomass and commercial & industrial waste) and identify the process steps which contribute more to the environmental burden. A scenario analysis on key processes, such as oxygen production technology, metal recovery and the appropriate choice for the secondary market aggregate material, is performed. The influence of accounting for the biogenic carbon content in the waste from the calculations of the global warming potential is also shown. Results show that the treatment of the refuse-derived fuel has the lowest impact in terms of both global warming potential and acidification potential because of its high heating value. For all the other impact categories analysed, the two-stage gasification and plasma process shows a negative impact for all the waste streams considered, mainly due to the avoided burdens associated with the production of electricity from the plant. The plasma convertor, key characteristic of the thermal process investigated, although utilising electricity shows a relatively small contribution to the overall environmental impact of the plant. The results do not significantly vary in the scenario analysis. Accounting for biogenic carbon enhanced the performance of biomass and refuse-derived fuel in terms of global warming potential. The main analysis of this study has been performed from a waste management perspective, using 1 ton of waste as functional unit. A comparison of the results when 1 kWhe of electricity produced is used as functional unit shows similar trends for the environmental impact categories considered.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

ANDRA's strategy and approach for post-closure safety of geological disposal - 15128

The French National Radioactive Waste Management Agency, or ANDRA, has, among its roles in management of radioactive waste, to ensure the protection of man and the environment from all radioactive waste generated in France. In order to verify compliance to the safety objectives, radiological and chemical impact evaluations are to be assessed. The objective of the paper is to present the overall approach for assessing the post-closure safety of French nuclear waste disposals in particular on the Geological Disposal. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

A Monte-Carlo Method for Evaluating the Economic Performance of Plastics Recycling Systems Using Historical Pricing

The management of plastic waste is a considerable emerging global concern. Conventional plastics recycling rates range from 5–10% in the US, which results in considerable material being sent to landfill. New sorting technologies using artificial intelligence have the potential to dramatically increase the ability of waste management companies to sort out valuable fractions of plastic waste and create high-purity streams for secondary markets. However, several fractions of the plastics recycling stream, i.e., low-density polyethylene, polypropylene, and polystyrene, do not have well-developed markets. These materials may be sent to pyrolysis facilities for thermal recycling, but the economics of the pyrolysis industry are currently uncertain. This work aims to identify the breakeven price of the plastic fractions that would be sent to pyrolysis in order to determine the economic viability of the sorting facility. The work will use Monte Carlo analysis to evaluate several scenarios and understand how compositional variation, price variability, and facility attributes affect the breakeven price. Here, the presorting conditions in Materials Recovery Facilities strongly affects the profitability of the sorting facility. High residual high density polyethylene (HDPE) and polyethylene terephthalate (PET) content in presorted bales are important revenue drivers for the facility, even in presorted 3-7 bales. Key variables that lead to profitability include a high sale price of polyethylene terephthalate, a high sale price of high-density polyethylene, and if polypropylene can be sold to recycling markets (as opposed to pyrolysis facilities).

Plastics↗
DOE OSTI2024

A Framework to Assess Advanced Reactor Spent Fuel Management Facility Deployment

Advanced nuclear reactors offer various operational advantages over existing light water reactors but could produce types of spent nuclear fuel (SNF) with a wide variety of forms and characteristics depending on how many different concepts are deployed. Each advanced reactor SNF type potentially poses unique management challenges. New planning efforts will be necessary to anticipate how the management requirements of advanced reactor SNF will affect the deployment of an integrated waste management system. This paper applies a framework of high-level facility deployment milestones to a generic SNF management system, reviewing them together with the advanced reactor SNF characteristics and management requirements. This allows for the investigation of factors that influence facility and system deployment, and ultimately, the identification of challenges facing the deployment of different kinds of SNF management facilities. Here, the back end of the once-through fuel cycle is examined for four advanced reactor system technology types: sodium-cooled fast reactors, high-temperature gas-cooled reactors, liquid-fuel molten salt reactors, and lead-cooled fast reactors. It is observed that milestones earlier in the facility deployment process (e.g., siting and facility design) are more impacted by the uniqueness of advanced reactor SNF characteristics than others (e.g., construction and testing). Ultimately, none of the differences are seen as fundamentally disqualifying in a technical sense; however, they should be considered early, potentially as part of reactor design, to avoid issues in the future.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Nuclear waste attributes of near-term deployable small modular reactors

The nuclear waste attributes of near-term deployable SMRs were assessed using established nuclear waste metrics, which are the DU mass, SNF mass, volume, activity, decay heat, radiotoxicity, and decommissioning LLW volumes. Metrics normalized per unit electricity generation were compared to a reference large PWR. Three SMRs, VOYGR, Natrium, and Xe-100, were selected because they represent a range of reactor and fuel technologies and are active designs deployable by the decade’s end. The SMR nuclear waste attributes show both some similarities to the PWR and some significant differences caused by reactor-specific design features. The DU mass is equivalent to or slightly higher than the PWR. Back-end waste attributes for SNF disposition vary, but the differences have a limited impact on long-term repository isolation. SMR designs can vary significantly in SNF volume (and thus heat generation density). However, these differences are amenable to design optimization for handling, storage, transportation, and disposal technologies. Nuclear waste attributes from decommissioning vary depending on design and decommissioning technology choices. Given the analysis results in this study and assuming appropriate waste management system and operational optimization, there appear to be no major challenges to managing SMR nuclear wastes compared to the reference PWR.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Source segregation and food waste prevention activities in high-density households in a deprived urban area

Highlights: • Study of waste management in economically and socially deprived high-density housing. • Food waste segregation, prevention and recycling activities investigated. • Study involved a waste audit and household survey of 1034 households. • Populations in such areas are “hard-to-reach”. • Exceptional efforts and additional resources are required to improve performance. - Abstract: A waste audit and a household questionnaire survey were conducted in high-density housing estates in one of the most economically and socially deprived areas of England (Haringey, London). Such areas are under-represented in published research. The study examined source segregation, potential participation in a food waste segregation scheme, and food waste prevention activities in five estates (1034 households). The results showed that: contamination of recyclables containers was low; ca. 28% of the mixed residual waste’s weight was recyclable; food waste comprised a small proportion of the waste from these residents, probably because of their relatively disadvantaged economic circumstances; and the recycling profile reflected an intermittent pattern of behaviour. Although the majority of respondents reported that they would participate in a food waste separation scheme, the response rate was low and many responses of “don’t know” were recorded. Municipalities committed to foster improved diversion from landfill need to recognise that there is no “quick and easy fix”, regardless of local or national aspirations. Lasting and sustained behaviour change requires time and the quality of service provision and associated infrastructure play a fundamental role in facilitating residents to participate effectively in waste management activities that maximise capture of source-segregated materials. Populations in deprived areas that reside in high-rise, high-density dwellings are “hard-to-reach” in terms of participation in recycling schemes and exceptional efforts and additional resources are usually required to improve performance.

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DOE OSTI2017

The Port Hope Area Initiative's Port Granby Project: From Planning to Execution - 17451

The Port Hope Area Initiative's Port Granby Project involves the construction of a new, secure long-term waste management facility (LTWMF) and supporting infrastructure, and the excavation and relocation of some 450,000 m{sup 3} of LLRW and marginally contaminated soil from the former Port Granby Waste Management Facility (PGWMF) to the newly constructed LTWMF. Presented is an overview of the Port Granby Project and a description of the planning needed to execute the project successfully. A comprehensive suite of approximately 40 pre-construction submittals were developed and submitted for review and approval by Canadian Nuclear Laboratories (CNL), the project authority. Importantly, comprehensive training programs were developed and implemented to ensure all project staff fully understood the scope of the planning documents (covering such things as Quality Control, Environmental Monitoring, Radiation Protection, Dust Management, Noise, Radiation Protection etc.) and possess the appropriate competencies for completing the work to which they have been assigned. The effective planning that has been invested in the Port Granby project, from initial design to project planning and implementation, has allowed this complex project to proceed with minimal difficulty. (authors)

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DOE OSTI2015

Economic aspects of thermal treatment of solid waste in a sustainable WM system

Highlights: • Provides a comprehensive review of the applied economic literature dedicated to WtE. • Offers a detailed discussion of the main assumptions that characterize alternative positions. • Highlights the most robust achievements obtained by the applied economic research in this field. • Compares economic and non-economic valuation techniques. - Abstract: This paper offers a systematic review of the literature of the last 15 years, which applies economic analysis and theories to the issue of combustion of solid waste. Waste incineration has attracted the interest of economists in the first place concerning the comparative assessment of waste management options, with particular reference to external costs and benefits. A second important field of applied economic research concerns the market failures associated with the provision of thermal treatment of waste, that justify some deviation from the standard competitive market model. Our analysis discusses the most robust achievements and the more controversial areas. All in all, the economic perspective seems to confirm the desirability of assigning a prominent role to thermal treatments in an integrated waste management strategy. Probably the most interesting original contribution it has to offer concerns the refusal of categorical assumptions and too rigid priority ladders, emphasizing instead the need to consider site-specific circumstances that may favor one or another solution.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Use of Automation in Low Level Waste Storage and Management - 19227

The Australian Nuclear Science and Technology Organisation (ANSTO) generates Low Level Waste (LLW) and Intermediate Level Waste (ILW) from various site operations such as the operation of a research Reactor and the manufacture of Molybdenum 99. The Low Level Solid Waste (LLSW) generated is stored at ANSTO before and after conditioning. The current process flow involves the storage of LLSW waste before conditioning on racks, handled using forklifts. When the unconditioned waste is ready for conditioning, it is transferred to another facility, where volume reduction and packaging is carried out. Once conditioned, the waste is placed in further storage, pending dispatch to the proposed Australian National Radioactive Waste Management Facility (NRWMF). A new purpose built facility has been constructed, adjacent to the LLSW processing facility, for the storage and management of LLSW in both unconditioned and conditioned forms. This new facility will streamline the waste management process and significantly enhance the safety and efficiency of the process. In line with international best practises, the new facility utilises automation solutions to minimise the build footprint, and minimise the use of forklifts and other mobile plant. Most importantly, it applies the principle of ALARA (As Low as Reasonably Achievable) to minimise operator activities in areas where radioactive material is stored and eliminates double handling of the waste. The automation for unconditioned waste utilises an Automated Storage and Retrieval System (ASRS), a vertical stacker crane within high density racking, to provide easy storage and retrieval for processing and/or routine inspections. This system allows operators to control it from outside of the storage area whilst utilising integrated software that allows for the required tracking of the unconditioned waste. From the ASRS storage area, unconditioned waste will have a smooth transition to the processing facility which is located adjacent to the ASRS system. Once conditioned, the waste is catalogued and returned to a designated storage area within the new facility using an automated building gantry crane with a target delivery system to eliminate the need for operators in the main storage bay. The waste will be held here in preparation for dispatch to the future repository. The utilisation of the ASRS for the purpose of storing LLSW is an innovative use of automation that will eliminate operators from active areas, reduce dose rates received and integrate with the waste tracking software. Furthermore, the system has significant advantages with operational efficiencies increased, reduced double handling of nuclear waste and maximum use of building footprint. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Model Package Report: Composite Analysis Solid Waste Release Model (CASWR Model)

This document describes the implementation of a solid waste form release model in GoldSim for the Hanford Site Composite Analysis (CA) Update. This Composite Analysis Solid Waste Release model (CASWR model) was designed to generate deterministic radionuclide release rates for Hanford’s Central Plateau solid waste disposal sites using single realizations of release model coefficients. Five generalized waste form types are used for the conceptual model of waste release: surplus reactor block, cement, soil-debris, grouted residual waste, and ancillary equipment. The surplus reactor block waste form consists of radionuclide leaching from surplus production graphite reactor core blocks via unspecified processes (White et al., 1984 as cited in PNNL-15965). The cement waste form represents solidified wastes whose permeability is much lower than that of the surrounding soil. The soil-debris waste form type is defined as unconsolidated waste mixed with soil material. Tanks and canyon complexes comprise the grouted residual waste form such that their solid waste will be grouted and capped with a surface barrier at the completion of their cleanup. Finally, the ancillary equipment waste form constitutes contaminant releases from ancillary and auxiliary waste form residues associated with tank farms at closure. Individual sub-models are implemented to numerically represent a respective waste form within the CASWR Model: Surplus Reactor Block Sub-model, Cement Sub-model, SoilDebris Sub-model, Grouted Residual Waste Sub-model, and Ancillary Equipment Submodel. Advection is assumed to be the primary transport process governing the release of radionuclides in the Ancillary Equipment and Soil-Debris Sub-models. Diffusion is assumed to be the primary release process in the Grouted Residual Waste and Cement Sub-models. An unspecified zero-order release process is considered in the Surplus Reactor Block Sub-model due to the lack of information regarding actual processes involved in irradiated graphite leaching. The Surplus Reactor Block, Cement, and SoilDebris Sub-models were compared against analytical solutions (PNNL-11800, Composite Analysis for Low-Level Waste Disposal in the 200 Area Plateau of the Hanford Site). The agreement between results of these analytical solutions and the corresponding waste form models verified their correct implementation in GoldSim. A 1-D modeling abstraction approach for the Grouted Residual Waste and Ancillary Equipment Sub-models was adopted from existing Performance Assessment (PA) models. Despite the simplifications made in these sub-models, they were found to be appropriate representations of the waste forms, similar to what was used in the Waste Management Area C PA model (RPP-ENV-58782, Performance Assessment of Waste Management Area C, Hanford Site, Washington, Rev. 0). A sensitivity analysis was conducted to identify the most influential parameters in each waste form sub-model. Suggestions for considering pH-dependent and redox-dependent release mechanisms are formulated through the development of a conditional constant approach in GoldSim.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Alternative D and D Planning Tool - 12466

On August 1, 2011, URS - CH2M Oak Ridge LLC (UCOR) began cleanup of the East Tennessee Technology Park (ETTP). UCOR's $2.2 billion contract has an initial five-year term and a four-year option period for completing the cleanup of ETTP and performing surveillance and maintenance and waste management operations at both the Oak Ridge National Laboratory and the Y-12 National Security Complex. ETTP D and D work includes disposition of large, complex, contaminated, Manhattan Project-era facilities such as the K-25 and K-27 uranium enrichment facilities. At ETTP, UCOR views the D and D process as a 'Waste Factory' with waste production lines from the point-of-generation to the point-of-disposal. Safely transforming vertically-standing buildings into horizontally-lying waste in a disposal facility is the primary cleanup objective. Whereas a factory produces widgets, D and D produces waste-lots of waste. In support of the Waste Factory view, UCOR is developing a systems planning tool to help better plan how to effect cleanup by improving waste planning, uniting waste generator with waste dis-positioner, and represent the 'waste factory' in a computer model that allows the D and D and waste management teams to better understand available disposal paths, waste uncertainties and potential consequences, driving variables, and sensitivity to changes. Any model of reality represents a compromise. Part of the Waste Factory Model's value may be in providing standardization and relative direction for assisting decision making as opposed to absolute cost or schedule answers. From that relative direction, management can commission detailed planning and estimating. Also, the model's output credibility is tied directly to its input quality. That is why, as discussed above, the Waste Factory Model's key informational component will be the standardized waste streams (e.g., Structure/Debris disposed at EMWMF) and associated standardized unit costs. The model development process generally, and the development team's collaboration, specifically, is most important. Building-in this integrity up-front, transparently, will help ensure that the model outputs are known, understood, and credible (no mysterious 'black-box' components). The Waste Factory Model is envisioned to help improve understanding of a given project's waste implications; help reveal and suggest the important few variables out of the trivial many; reveal likely process bottlenecks, and help focus risk mitigation and assumption management efforts to better manage the projected total cost. In the long term, the UCOR team's goal is to incorporate an information feedback loop to help improve the accuracy of key model attributes, such as the standardized cost information. This way, by design, the model output should improve over time and thus help the model mature into both a credible scenario tool and a standardized project planning resource. The initial model capabilities may be narrow, but with time and effort it may prove to be a timely and cost-effective tool. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Removal of Historic Low-Level Radioactive Sediment from the Port Hope Harbour - 13314

At the Port Hope Harbour, located on the north shore of Lake Ontario, the presence of low-level radioactive sediment, resulting from a former radium and uranium refinery that operated alongside the Harbour, currently limits redevelopment and revitalization opportunities. These waste materials contain radium-226, uranium, arsenic and other contaminants. Several other on-land locations within the community of Port Hope are also affected by the low-level radioactive waste management practices of the past. The Port Hope Project is a community initiated undertaking that will result in the consolidation of an estimated 1.2 million cubic metres of the low-level radioactive waste from the various sites in Port Hope into a new engineered above ground long-term waste management facility. The remediation of the estimated 120,000 m{sup 3} of contaminated sediments from the Port Hope Harbour is one of the more challenging components of the Port Hope Project. Following a thorough review of various options, the proposed method of contaminated sediment removal is by dredging. The sediment from the dredge will then be pumped as a sediment-water slurry mixture into geo-synthetic containment tubes for dewatering. Due to the hard substrate below the contaminated sediment, the challenge has been to set performance standards in terms of low residual surface concentrations that are attainable in an operationally efficient manner. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Issue Resolution During the Development of the Performance Assessment for the Savannah River Site Saltstone Disposal Facility - 20125

In 2019, Savannah River Remediation developed a revision to the performance assessment (PA) on behalf of the U.S. Department of Energy (DOE) Savannah River Operations Office (SR) for the near-surface disposal of low-level waste at the Savannah River Site (SRS) Saltstone Disposal Facility (SDF). Soluble waste from SRS Tank Farms undergoes salt processing to remove cesium and other high-activity constituents. The low-activity decontaminated salt solution (DSS) is then immobilized by mixing it into a cementitious waste form known as saltstone. After mixing, the saltstone is poured into leak-tight concrete vaults, known as saltstone disposal units (SDUs), where the waste form cures. By the time of facility closure, the SDF is expected to consist of 15 SDUs with a combined capacity of 1.06 E+09 L (280 Mgal) of cured saltstone. The facility operates under a Disposal Authorization Statement from DOE and a permit from the South Carolina Department of Health and Environmental Control (SCDHEC). Since the start of operations in 1990, the SDF has received almost 6.7 E+07 L (18 Mgal) of DSS, resulting in the safe disposal of 2.7 E+16 Bq (7.3 E+05 Ci) of activity. Due to the radioactive decay of short-lived contaminants, the total remaining activity in the disposed waste is estimated to be approximately 1.4 E+16 Bq (3.9 E+05 Ci), as of September 2018. The Disposal Authorization Statement requires a demonstration that the system of engineered and natural features of the disposal facility will limit releases from the facility and be protective of human health and the environment for at least the next 1,000 years. The long-term performance of the facility was evaluated under the requirements of the DoE's Radioactive Waste Management Manual (US DOE Manual 435.1-1). Simulations were performed to demonstrate that the disposal facility would meet performance objectives specified in the manual. The evaluation was based on numerical models that simulate the releases of contaminants from the saltstone waste form. Contaminants were transported through groundwater and air pathways to points of assessment to evaluate compliance (i.e., 100 m from the SDUs). In addition, the potential consequences of an inadvertent human intrusion (IHI) were also evaluated. A number of issues were overcome during the development of these simulations. These issues were identified as part of internal technical reviews. Simulations are developed by people and people make mistakes, so the internal technical review process is a vital step in PA development. Specific examples of resolved issues include a unit-conversion error, an inappropriate definition for a model boundary condition, a model time-stepping issue, and an error in the calculation for the buildup of contaminants in soil. Actions taken to address these issues resulted in an improved product with a better supported technical basis and more defensible results. The identification and correction of these issues are discussed. By understanding these issues, model developers and technical reviewers working on PAs in the future may avoid repeating these types of mistakes. Transparency with respect to these mistakes builds trust between waste management sites, regulators, and stakeholders. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Decommissioning and PIE of the MEGAPIE spallation target

A key experiment in the Accelerated Driven Systems roadmap, the MEGAwatt PIlot Experiment (MEGAPIE) (1 MW) was initiated in 1999 in order to design and build a liquid lead-bismuth spallation target, then to operate it into the Swiss spallation neutron facility SINQ at Paul Scherrer Institute. The target has been designed, manufactured, and tested during integral tests, before irradiation carried out end of 2006. During irradiation, neutron and thermo hydraulic measurements were performed allowing deep interpretation of the experiment and validation of the models used during design phase. The decommissioning, Post Irradiation Examinations and waste management phases were defined properly. The phases dedicated to cutting, sampling, cleaning, waste management, samples preparation and shipping to various laboratories were performed by PSI teams: all these phases constitute a huge work, which allows now to perform post-irradiation examination (PIE) of structural material, irradiated in relevant conditions. Preliminary results are presented in the paper, they concern chemical characterization. The following radio-nuclides have been identified by γ-spectrometry: {sup 60}Co, {sup 101}Rh, {sup 102}Rh, {sup 108m}Ag, {sup 110m}Ag, {sup 133}Ba, {sup 172}Hf/Lu, {sup 173}Lu, {sup 194}Hg/Au, {sup 195}Au, {sup 207}Bi. For some of these nuclides the activities can be easily evaluated from γ-spectrometry results ({sup 207}Bi, {sup 194}Hg/Au), while other nuclides can only be determined after chemical separations ({sup 108m}Ag, {sup 110m}Ag, {sup 195}Au, {sup 129}I, {sup 36}Cl and α-emitting {sup 208-210}Po). The concentration of {sup 129}I is lower than expected. The chemical analysis already performed on spallation and corrosion products in the lead-bismuth eutectic (LBE) are very relevant for further applications of LBE as a spallation media and more generally as a coolant.

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