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DOE OSTI2016

Extending Spent Fuel Storage until Transport for Reprocessing or Disposal

Spent fuel (SF) must be stored until an end point such as reprocessing or geologic disposal is imple-mented. Selection and implementation of an end point for SF depends upon future funding, legisla-tion, licensing and other factors that cannot be predicted with certainty. Past presumptions related to the availability of an end point have often been wrong and resulted in missed opportunities for properly informing spent fuel management policies and strategies. For example, dry cask storage systems were originally conceived to free up needed space in reactor spent fuel pools and also to provide SFS of up to 20 years until reprocessing and/or deep geological disposal became available. Hundreds of dry cask storage systems are now employed throughout the world and will be relied upon well beyond the originally envisioned design life. Given present and projected rates for the use of nuclear power coupled with projections for SF repro-cessing and disposal capacities, one concludes that SF storage will be prolonged, potentially for several decades. The US Nuclear Regulatory Commission has recently considered 300 years of storage to be appropriate for the characterization and prediction of ageing effects and ageing management issues associated with extending SF storage and subsequent transport. This paper encourages addressing the uncertainty associated with the duration of SF storage by de-sign – rather than by default. It suggests ways that this uncertainty may be considered in design, li-censing, policy, and strategy decisions and proposes a framework for safely extending spent fuel storage until SF can be transported for reprocessing or disposal – regardless of how long that may be. The paper however is not intended to either encourage or facilitate needlessly extending spent fuel storage durations. Its intent is to ensure a design and safety basis with sufficient margin to accommodate the full range of potential future scenarios. Although the focus is primarily on storage of SF from commercial operation, the principles described are equally applicable to SF from research and production reactors as well as high-level radioactive waste.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Issues and Recommendations Arising from the Idaho National Laboratory Remote-Handled Low-Level Waste Disposal Facility Composite Analysis - 13374

Development of the composite analysis (CA) for the Idaho National Laboratory's (INLs) proposed remote-handled (RH) low-level waste (LLW) disposal facility has underscored the importance of consistency between analyses conducted for site-specific performance assessments (PAs) for LLW disposal facilities, sites regulated by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) [1], and residual decontamination and decommissioning (D and D) inventories. Consistency is difficult to achieve because: 1) different legacy sources and compliance time-periods were deemed important for each of the sites evaluated at INL (e.g., 100 years for CERCLA regulated facilities vs. 1,000 years for LLW disposal facilities regulated under U.S. Department of Energy (DOE) Order 435.1 [2]); 2) fate and transport assumptions, parameters, and models have evolved through time at the INL including the use of screening-level parameters vs. site-specific values; and 3) evaluation objectives for the various CERCLA sites were inconsistent with those relevant to either the PA or CA including the assessment of risk rather than effective dose. The proposed single site-wide CA approach would provide needed consistency, allowing ready incorporation of new information and/or facilities in addition to being cost effective in terms of preparation of CAs and review by the DOE. A single site-wide CA would include a central database of all existing INL sources, including those from currently operating LLW facilities, D and D activities, and those from the sites evaluated under CERCLA. The framework presented for the INL RH-LLW disposal facility allows for development of a single CA encompassing air and groundwater impacts. For groundwater impacts, a site-wide MODFLOW/MT3D-MS model was used to develop unit-response functions for all potential sources providing responses for a grid of receptors. Convolution and superposition of the response functions are used to compute groundwater concentrations. A similar approach could be applied for the air pathway where air emissions are stored in a central database and air concentrations for unit releases could be scaled to actual releases. (authors)

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DOE OSTI2013

A Study on Optimized Management Options for the Wolsong Low- and Intermediate - Level Waste Disposal Center in Korea - 13479

The safe and effective management of radioactive waste is a national task required for sustainable generation of nuclear power and for energy self-reliance in Korea. Currently, for permanent disposal of low- and intermediate-level waste (LILW), the Wolsong LILW Disposal Center (WLDC) is under construction. It will accommodate a total of 800,000 drums at the final stage after stepwise expansion. As an implementing strategy for cost-effective development of the WLDC, various disposal options suitable for waste classification schemes would be considered. It is also needed an optimized management of the WLDC by taking a countermeasure of volume reduction treatment. In this study, various management options to be applied to each waste class are analyzed in terms of its inventory and disposal cost. For the volume reduction and stabilization of waste, the vitrification and plasma melting methods are considered for combustible and incombustible waste, respectively. (authors)

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DOE OSTI2012

Implementing Geological Disposal of Radioactive Waste Technology Platform From the Strategic Research Agenda to its Deployment - 12015

Several European waste management organizations (WMOs) have initiated a technology platform for accelerating the implementation of deep geological disposal of radioactive waste in Europe. The most advanced waste management programmes in Europe (i.e. Finland, Sweden, and France) have already started or are prepared to start the licensing process of deep geological disposal facilities within the next decade. A technology platform called Implementing Geological Disposal of Radioactive Waste Technology Platform (IGD-TP) was launched in November 2009. A shared vision report for the platform was published stating that: 'Our vision is that by 2025, the first geological disposal facilities for spent fuel, high-level waste, and other long-lived radioactive waste will be operating safely in Europe'. In 2011, the IGD-TP had eleven WMO members and about 70 participants from academia, research, and the industry committed to its vision. The IGD-TP has started to become a tool for reducing overlapping work, to produce savings in total costs of research and implementation and to make better use of existing competence and research infrastructures. The main contributor to this is the deployment of the IGD-TP's newly published Strategic Research Agenda (SRA). The work undertaken for the SRA defined the pending research, development and demonstration (RD and D) issues and needs. The SRA document describing the identified issues that could be worked on collaboratively was published in July 2011. It is available on the project's public web site (www.igdtp.eu). The SRA was organized around 7 Key Topics covering the Safety Case, Waste forms and their behaviour, Technical feasibility and long-term performance of repository components, Development strategy of the repository, Safety of construction and operations, Monitoring, and Governance and stakeholder involvement. Individual Topics were prioritized within the Key Topics. Cross-cutting activities like Education and Training or Knowledge Management as well as activities remaining specific for the WMOs were as well identified in the document. For example, each WMO has to develop their own waste acceptance rules, and plan for the economics and the funding of their waste management programmes. The challenge at hand for the IGD-TP is to deploy the SRA. This is carried out by agreeing on a Deployment Plan (DP) that guides organizing the concrete joint activities between the WMOs and the other participants of the IGD-TP. The first DP points out the coordinated RD and D projects and other activities that need to be launched to produce these results over the next four to five years (by the end of 2016). The DP also describes general principles for how the joint work can be organised and funded. (authors)

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DOE OSTI2012

Container Approval for the Disposal of Radioactive Waste with Negligible Heat Generation in the German Konrad Repository - 12148

Since the license for the Konrad repository was finally confirmed by legal decision in 2007, the Federal Institute for Radiation Protection (BfS) has been performing further planning and preparation work to prepare the repository for operation. Waste conditioning and packaging has been continued by different waste producers as the nuclear industry and federal research institutes on the basis of the official disposal requirements. The necessary prerequisites for this are approved containers as well as certified waste conditioning and packaging procedures. The Federal Institute for Materials Research and Testing (BAM) is responsible for container design testing and evaluation of quality assurance measures on behalf of BfS under consideration of the Konrad disposal requirements. Besides assessing the container handling stability (stacking tests, handling loads), design testing procedures are performed that include fire tests (800 deg. C, 1 hour) and drop tests from different heights and drop orientations. This paper presents the current state of BAM design testing experiences about relevant container types (box shaped, cylindrical) made of steel sheets, ductile cast iron or concrete. It explains usual testing and evaluation methods which range from experimental testing to analytical and numerical calculations. Another focus has been laid on already existing containers and packages. The question arises as to how they can be evaluated properly especially with respect to lack of completeness of safety assessment and fabrication documentation. At present BAM works on numerous applications for container design testing for the Konrad repository. Some licensing procedures were successfully finished in the past and BfS certified several container types like steel sheet, concrete until cast iron containers which are now available for waste packaging for final disposal. However, large quantities of radioactive wastes had been placed into interim storage using containers which are not already licensed for the Konrad repository. Safety assessment of these so-called 'old' containers is a big challenge for all parties because documentation sheets about container design testing and fabrication often contain gaps or have not yet been completed. Appropriate solution strategies are currently under development and discussion. Furthermore, BAM has successfully initiated and established an information forum, called 'ERFA QM Konrad Containers', which facilitates discussions on various issues of common interest with respect to Konrad container licensing procedures as well as the interpretation of disposal requirements under consideration of operational needs. Thus, it provides additional, valuable supports for container licensing procedures. (authors)

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DOE OSTI2012

International Socio-Technical Challenges for Geological Disposal (InSOTEC): Project Aims and Preliminary Results - 12236

InSOTEC is a social sciences research project which aims to generate a better understanding of the complex interplay between the technical and the social in radioactive waste management and, in particular, in the design and implementation of geological disposal. It currently investigates and analyses the most striking socio-technical challenges to implementing geological disposal of radioactive waste in 14 national programs. A focus is put on situations and issues where the relationship between the technical and social components is still unstable, ambiguous and controversial, and where negotiations are taking place in terms of problem definitions and preferred solutions. Such negotiations can vary from relatively minor contestation, over mild commotion, to strong and open conflicts. Concrete examples of socio-technical challenges are: the question of siting, introducing the notion of reversibility / retrievability into the concept of geological disposal, or monitoring for confidence building. In a second stage the InSOTEC partners aim to develop a fine-grained understanding of how the technical and the social influence, shape, build upon each other in the case of radioactive waste management and the design and implementation of geological disposal. How are socio-technical combinations in this field translated and materialized into the solutions finally adopted? With what kinds of tools and instruments are they being integrated? Complementary to providing better theoretical insight into these socio-technical challenges/combinations, InSOTEC aims to provide concrete suggestions on how to address these within national and international contexts. To this end, InSOTEC will deliver insights into how mechanisms for interaction between the technical community and a broad range of socio-political actors could be developed. (authors)

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DOE OSTI2012

Probabilistic Modeling of Settlement Risk at Land Disposal Facilities - 12304

The long-term reliability of land disposal facility final cover systems - and therefore the overall waste containment - depends on the distortions imposed on these systems by differential settlement/subsidence. The evaluation of differential settlement is challenging because of the heterogeneity of the waste mass (caused by inconsistent compaction, void space distribution, debris-soil mix ratio, waste material stiffness, time-dependent primary compression of the fine-grained soil matrix, long-term creep settlement of the soil matrix and the debris, etc.) at most land disposal facilities. Deterministic approaches to long-term final cover settlement prediction are not able to capture the spatial variability in the waste mass and sub-grade properties which control differential settlement. An alternative, probabilistic solution is to use random fields to model the waste and sub-grade properties. The modeling effort informs the design, construction, operation, and maintenance of land disposal facilities. A probabilistic method to establish design criteria for waste placement and compaction is introduced using the model. Random fields are ideally suited to problems of differential settlement modeling of highly heterogeneous foundations, such as waste. Random fields model the seemingly random spatial distribution of a design parameter, such as compressibility. When used for design, the use of these models prompts the need for probabilistic design criteria. It also allows for a statistical approach to waste placement acceptance criteria. An example design evaluation was performed, illustrating the use of the probabilistic differential settlement simulation methodology to assemble a design guidance chart. The purpose of this design evaluation is to enable the designer to select optimal initial combinations of design slopes and quality control acceptance criteria that yield an acceptable proportion of post-settlement slopes meeting some design minimum. For this specific example, relative density, which can be determined through field measurements, was selected as the field quality control parameter for waste placement. This technique can be extended to include a rigorous performance-based methodology using other parameters (void space criteria, debris-soil mix ratio, pre-loading, etc.). As shown in this example, each parameter range, or sets of parameter ranges can be selected such that they can result in an acceptable, long-term differential settlement according to the probabilistic model. The methodology can also be used to re-evaluate the long-term differential settlement behavior at closed land disposal facilities to identify, if any, problematic facilities so that remedial action (e.g., reinforcement of upper and intermediate waste layers) can be implemented. Considering the inherent spatial variability in waste and earth materials and the need for engineers to apply sound quantitative practices to engineering analysis, it is important to apply the available probabilistic techniques to problems of differential settlement. One such method to implement probability-based differential settlement analyses for the design of landfill final covers has been presented. The design evaluation technique presented is one tool to bridge the gap from deterministic practice to probabilistic practice. (authors)

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DOE OSTI2012

Salt Disposal Investigations to Study Thermally Hot Radioactive Waste In A Deep Geologic Repository in Bedded Rock Salt - 12488

A research program is proposed to investigate the behavior of salt when subjected to thermal loads like those that would be present in a high-level waste repository. This research would build upon results of decades of previous salt repository program efforts in the US and Germany and the successful licensing and operation of a repository in salt for disposal of defense transuranic waste. The proposal includes a combination of laboratory-scale investigations, numerical simulations conducted to develop validated models that could be used for future repository design and safety case development, and a thermal field test in an underground salt formation with a configuration that replicates a small portion of a conceptual repository design. Laboratory tests are proposed to measure salt and brine properties across and beyond the range of possible repository conditions. Coupled numerical models will seek to describe phenomenology (thermal, mechanical, and hydrological) observed in the laboratory tests. Finally, the field test will investigate many phenomena that have been variously cited as potential issues for disposal of thermally hot waste in salt, including buoyancy effects and migration of pre-existing trapped brine up the thermal gradient (including vapor phase migration). These studies are proposed to be coordinated and managed by the Carlsbad Field Office of DOE, which is also responsible for the operation of the Waste Isolation Pilot Plant (WIPP) within the Office of Environmental Management. The field test portion of the proposed research would be conducted in experimental areas of the WIPP underground, far from disposal operations. It is believed that such tests may be accomplished using the existing infrastructure of the WIPP repository at a lower cost than if such research were conducted at a commercial salt mine at another location. The phased field test is proposed to be performed over almost a decade, including instrumentation development, several years of measurements during heating and then subsequent cooling periods, and the eventual forensic mining back of the test bed to determine the multi-year behavior of the simulated waste/rock environment. Funding possibilities are described, and prospects for near term start-up are discussed. Mining of the access drifts required to create the test area in the WIPP underground began in November 2011. Because this mining uses existing WIPP infrastructure and labor, it is estimated to take about two years to complete the access drifts. WIPP disposal operations and facility maintenance activities will take priority over the SDI field test area mining. Funding of the SDI proposal was still being considered by DOE's Offices of Environmental Management and Nuclear Energy at the time this paper was written, so no specific estimates of the progress in 2012 have been included. (authors)

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DOE OSTI2012

Disposing of High-Level Radioactive Waste in Germany - A Note from the Licensing Authority - 12530

Following the national German consensus on the termination of utilisation of nuclear energy in the summer of 2011, the Federal and Laender Governments have declared their intention to work together on a national consensus on the disposal of radioactive waste as well. Projected in the early 1970's the Federal Government had started exploring the possibility to establish a repository for HLW at the Gorleben site in 1977. However, there is still no repository available in Germany today. The delay results mainly from the national conflict over the suitability of the designated Gorleben site, considerably disrupting German society along the crevice that runs between supporters and opponents of nuclear energy. The Gorleben salt dome is situated in Lower Saxony, the German state that also hosts the infamous Asse mine repository for LLW and ILW and the Konrad repository project designated to receive LLW and ILW as well. With the fourth German project, the Morsleben L/ILW repository only 20 km away across the state border, the state of Lower Saxony carries the main load for the disposal of radioactive waste in Germany. After more than 25 years of exploration and a 10 year moratorium the Gorleben project has now reached a cross-road. Current plans for setting up a new site selection procedure in Germany call for the selection and exploration of up to four alternative sites, depending only on suitable geology. In the meantime the discussion is still open on whether the Gorleben project should be terminated in order to pacify the societal conflict or being kept in the selection process on account of its promising geology. The Lower Saxony Ministry for Environment and Climate Protection proposes to follow a twelve-step-program for finding the appropriate site, including the Gorleben site in the process. With its long history of exploration the site is the benchmark that alternative sites will have to compare with. Following the national consensus of 2011 on the termination of nuclear energy utilisation, it is now the time to reach a national consensus on the disposal of radioactive waste as well. This is a task that the country and society, federal and state governments, political parties and the citizens will have to jointly master within the current generation and within German territory. The basis for the consensus will be a reset to the beginning of this process. It has to start with a new site selection procedure that will take into account and compare up to four alternative sites. This procedure will have to follow the principle of highest possible security. It should be based on a stepwise approach, strictly following scientific criteria. Public confidence in the process and trust can only be achieved by a transparent procedure allowing for the participation of the public and the stakeholders. It is therefore mandatory to consult, both on a national and regional level, all involved parties (public authority, scientist and citizen). The national consensus must also include a decision on the future of the Gorleben exploratory site. The site selection procedure must therefore take this site into account as well. Furthermore, the final decision on safe disposal of German radioactive wastes must be made by sovereign rule by Federal Parliament and Federal Council. (authors)

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DOE OSTI2017

Probabilistic Performance Assessment for Deep Borehole Disposal of Cs/Sr Capsules - 17143

The US Department of Energy (DOE) performed an assessment of disposal options for spent nuclear fuel (SNF) and high-level radioactive waste (HLW) that recommended the consideration of deep borehole disposal (DBD) of smaller DOE-managed waste forms, such as cesium (Cs) and strontium (Sr) capsules. To further assess the safety and viability of the DBD concept, post-closure performance assessment (PA) analyses were performed for DBD of Cs/Sr capsules. The post-closure PA included a reference design concept for Cs/Sr capsule disposal, feature, event, and process (FEP) analysis, scenario development, and modeling using the PFLOTRAN code. PA simulations were run for both nominal and disturbed scenarios for long-term radionuclide transport away from the deep disposal borehole. The nominal (expected) post-closure release scenario included FEPs for short-duration (a few hundred years) thermally-induced upward fluid flux through the borehole seals and/or disturbed rock zone (DRZ) followed by longer-term slow diffusive transport. Simulations included a baseline deterministic run and a set of probabilistic realizations (using Latin Hypercube Sampling (LHS) from parameter distributions) to examine the sensitivity and importance of the long-term radionuclide transport to processes and parameters such as: waste package durability; seal porosity and permeability, disturbed rock zone (DRZ) porosity and permeability; and radionuclide sorption in the seal materials, DRZ, and crystalline host rock. The disturbed scenario included a waste package 'stuck' in the crystalline basement above the emplacement zone near a hypothetical borehole-intersecting fracture. Simulations included two deterministic runs to examine the sensitivity to the regional head gradient. The nominal and disturbed scenario PA results suggest that a favorable safety case can be developed for DBD of Cs/Sr capsules and helped to identify key areas of uncertainty, which in turn can inform future DBD research and development (R and D) activities, including a field demonstration project. (authors)

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DOE OSTI2017

Solid Secondary Waste Form Testing Activities for the Integrated Disposal Facility Performance Assessment Support - 17567

Solid secondary waste (SSW) that will be generated at the Waste Treatment and Immobilization Plant (WTP) and from other activities at the Hanford site is destined for disposal at the Integrated Disposal Facility (IDF). Construction of the IDF was undertaken based on a Performance Assessment (PA) performed in 2001. In 2016, a SSW data package was prepared to support the development of an updated PA (2017 IDF PA). There are many inputs required to support the IDF PA. Data needs were identified based on experience from the previous PAs and from the development of conceptual models and modeling approaches to be applied for the 2017 PA. Interactions with the IDF PA team and the inventory data package developer helped to focus detailed efforts on a few key waste streams, contaminants of concern, and disposal configurations that are expected to be the primary contributors to the dose resulting from SSW disposed at the IDF. The key waste streams include: High Efficiency Particulate Air (HEPA) filters, ion exchange resins, granular activated carbon, and Ag-mordenite. The key parameters addressed in the 2016 data package include: saturated hydraulic conductivity, moisture characteristic curves, effective diffusion coefficient, distribution coefficient and porosity. The IDF PA team also identified a set of key contaminants that are expected to be the primary concern for the PA calculations (Tc-99, I-129, Cs-137, Sr-90, uranium isotopes (and total uranium), chromium, mercury and nitrate). These contaminants were the focus of the SSW data package. Specific formulations had not been identified for cementitious materials that will be used to encapsulate or stabilize SSW, and no IDF-specific experiments had been conducted to obtain the data for the PA. Thus, for the 2016 SSW data package, recommended property values were provided for a range of representative candidate materials based on a review of existing literature. However, starting in FY17, IDF-specific experiments will be performed for Hanford SSW expected to contribute most significantly to the dose for the IDF. This paper will summarize the information obtained for the 2016 data package and the plans for further testing to refine key inputs for the IDF PA. (authors)

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DOE OSTI2017

A Study Of Geological Disposal Facility (GDF) Ageing Phenomena In Bentonite - 17605

Since the 1950's, the UK's nuclear activity in energy, defence and medicine has led to the accumulation of a large amount of higher activity radioactive waste (HAW). Most of nuclear waste arises in a wide variety of physical and chemical forms with different radioisotopes and loadings. Due to complexity in HAW, it is imperative that there be a rigorous management system that ensures population and environmental safety over extended periods. The concept of Deep Geological Disposal of waste in a stable geological formation is, nowadays, an internationally accepted solution as the surest and the most viable long term method for management. Any future Geological Disposal Facility (GDF) will comprise, among other artificial and natural engineered barriers, a barrier immediately around the waste containers compounded by a sealing material. The long-term stability of a GDF will be determined by the design and construction of the engineered barriers, and the mechanical, hydraulic and geochemical interactions that may happen between the different engineered components as a result of combined processes such as the heat produced by radioactive decay and the ion water composition of the surrounding host rock. Bentonite clay has been selected as the most promising buffer and backfill material in many disposal programmes because of its swelling capacity, low permeability, plasticity and cation exchange capacity. In the nuclear scope, bentonite testing at different scale-lengths (laboratory and field scale) has been performed and implemented in order to examine the thermo-hydro-mechanical (THM) and thermo-hydro-geochemical (THG) processes that may happen in the engineered barriers and geological settings associated with a GDF. Two major European field scale tests have been performed to better understand bentonite performance and behaviour immediately after HAW emplacements. The Full-Scale Engineered Barriers Experiment (FEBEX) at the Grimsel Test Sit (Switzerland) and the Alternative Buffer Material (ABM) Project at the Aespoe Hard Rock Laboratory (Sweden). The Febex Experiment was a pilot project designed for 'field research' of HAW repository hosted in crystalline rock where surrogate HAW canisters were placed horizontally in drifts, surrounded by compacted blocks of bentonite, sealed by a concrete plug and maintaining a constant canister surface temperature of 100 deg. C. After five years of operation, a partial dismantling was carried out in 2002. Heater processes occurring in the surrounding bentonite. The dismantling of the heater no. 2 (after 18 years of operation) started in late 2014 and is planned to be finished at the end of 2016 (termed FEBEX-DP). The FEBEX Project utilised bentonite from the Cortijo de Archidona deposit (Almeria, Spain). This 'Febex' bentonite is sourced from calcium-magnesium montmorillonite with good properties in relation to swelling capacity, permeability, adsorption capacity, and thermal conductivity. The ABM Project is a large-scale programme that has been running since 2006. The programme is designed to study a suite of possible buffer materials and correlate the physical and chemical properties of eleven different types of bentonites to their fundamental mineralogical properties. The ABM test consists in three 'packages' containing a central heater tube surrounded by different pre-compacted bentonite blocks and instrumentation. Each 'package' was installed in separate boreholes. The target temperature for the surface of the heated tubes in contact with the bentonite was 130 deg. C. Both FEBEX and ABM test the bentonite was saturated with water percolating from surrounding host rock (FEBEX and ABM) and also via artificial supply systems (ABM), being the water itself acting as a long term corrosion agent. For both experiments and emerging interest is in the interaction of bentonite with metallic components, under geological disposal conditions are not considered to be thermodynamically stable and hence arising corrosion products could interact with the buffer. These interactions depend on various factors such as the redox potential, temperature, pH, solute concentration and buffer material characteristics. During the operational phases of the FEBEX and ABM and after its 'closure' a significant volume of air was found to be retained in the bentonite. Under these conditions a period of initial aerobic corrosion by the air in the bentonite barrier would have occurred followed by establishment of anaerobic corrosion would be the dominant process ongoing. The anaerobic corrosion began when the bentonite became water saturated. Under these conditions, the water acted as the major oxidant. The present project focuses on the characterization of samples arising from the FEBEX and ABM Projects as well as performing additional independent experiments designed to complement these prior studies. Characterization will focus mainly on corrosion related alteration combined with thermal effects. Through detailed sample characterization, the intention is to achieve a greater knowledge regarding the changes to the bentonite under the experimental conditions to which it was exposed, and plausible alterations in its THM and THG properties occurring during the experiment due to blended effects of temperature,water content, engineering structural components and solutes are also to be measured. The fulfilment of a large-scale 'in-situ' test is intricate, time-consuming and with an abundance of external variables that are not always well controlled. For this reason, the University of Bristol is performing a series of well constrained time-resolved laboratory tests which bentonite is being subjected to different possible scenarios that may happen whilst in a HAW repository. In virtue of this experiment, the UoB aims to understand the illitisation and cementation process and their effects on bentonite safety properties. (authors)

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

Mega salt-stone Disposal Units at the Savannah River site - 15322

The Liquid Waste (LW) System at Savannah River Site (SRS) is a highly integrated operation involving safely storing radioactive liquid waste in underground storage tanks; vitrifying the higher activity waste; and storing the vitrified waste in stainless steel canisters until permanent disposition is provided; and removing, treating, and dispositioning the low-level waste (LLW) fraction in concrete with final disposition being the salt-stone Disposal Units (SDUs) at the SRS salt-stone Disposal Facility (SDF). Treatment and disposition of salt waste is the critical path to completion of the SRS Liquid Waste (LW) Disposition Program. Successful and timely salt waste removal and disposal is integral to efforts by SRS to proceed with all aspects of tank cleanup and removal from service. The construction and implementation of the first-of-a-kind Mega SDU (MSDU) is underway to provide the most environmentally safe and cost-effective solution for salt processing and long term storage of the LLW at SRS. The MSDU design is a duplicate of the Water Treatment Tanks located in Syracuse, New York. This commercial design, developed by an affiliate of Savannah River Remediation LLC (SRR), was slightly modified to meet the requirements of the nuclear industry. The MSDU is a critical link in salt disposition. In comparison to the current SDU design, approximately 46 meters (150 feet) in diameter and 7 meters (22 feet) tall with a capacity of approximately 11,000 m{sup 3} (3.0 million gallons), the MSDU is 114 meters (375 feet) in diameter and 13 meters (43 feet) tall which will provide a capacity of approximately 121,000 m{sup 3} (32.0 million gallons) to receive the LLW fraction embedded in a grout-like form. The MSDU will provide the taxpayers an estimated $300 M in life cycle savings at SRS by reducing the number of SDUs from the estimated 72 smaller vessels to 7 of the new larger vessels. Additionally, based on the reduced number of SDUs, the environmental footprint is significantly reduced as well. Due to the similarities between the existing SDU design and the MSDU design, efforts to integrate the MSDU into the LW system are minimal. Required infrastructure modifications will consist of tying into the existing grout and drain lines, as well as the installation of new electrical and instrumentation services for the MSDU. Grout flow testing has been successfully completed, with results showing the MSDU will be a safe and cost-effective replacement for the existing SDUs. The MSDU design is complete, Critical Decision (CD)-3 was approved on June 17, 2014, and the first MSDU, salt-stone Disposal Unit n.6 (SDU 6), is being constructed in the existing LW SDF operated by SRR as a Capital Line Item project. As an added benefit, once constructed, lessons learned will be available for future MSDUs at SRS and throughout the complex as necessary. (authors)

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DOE OSTI2015

Commercial sealed sources and timely disposal: Challenges and incentives - 15456

It is widely accepted as a radioactive material management best-practice that storage of disused sealed sources should be a temporary measure. Effective end-of-life management, including timely disposition of disused and unwanted sealed sources, is an important way to address national security, public health, and safety concerns presented by long-term storage of disused sealed sources. However, significantly increased disposal access since 2012 has not led commercial sealed source generators in the U.S. to dispose of their disused and unwanted sources as quickly as many had expected. As a result, policy-makers and non-government stakeholders are considering ways to incentivize sealed source generators to make more timely decisions regarding the disposition of their disused and unwanted sources. To help ensure that ongoing efforts to develop sealed source management and disposal incentives are efficient and effective, NNSA/GMS is engaging both public and private sector partners to better understand generator considerations, motivations, and challenges with regard to sealed source management and disposal decisions. The results of these engagements to date indicate potentially effective ways to encourage sealed source waste generators to disposition their sources in a timely fashion. (authors)

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DOE OSTI2016

Cost Savings Resulting From Classified Component Disposal at the Nevada National Security Site (NNSS) - 16440

This paper discusses the Nevada National Security Site (NNSS) capability to dispose of both radioactive and non-radioactive classified components and the tremendous cost-avoidance in storage, sanitization and/or demilitarization (Demil), and disposal that have been experienced by generators. One generator, The U.S. Air Force Materiel Command (AFMC), 414. Supply Chain Management Squadron out of Hill Air Force Base (HAFB) experienced total cost-avoidance in the last two years of $218 million on an investment of $1.9 million for disposal at the NNSS. They also accelerated the planned component disposition schedule by 7 years. In 2012, the NNSS added the capability of meeting a key national resource for the safe, secure disposal of classified components that have been declared excess to national security requirements. Since that time the program has continued to grow and expand. (authors)

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DOE OSTI2019

Concept for Operation of the Belgian Geological Disposal Facility for Category B and C Wastes - 19247

For more than 40 years, ONDRAF/NIRAS (the federal agency responsible for managing radioactive waste and enriched fissile materials in Belgium) has been studying the concept of a geological disposal facility (GDF) in poorly indurated clays as an option for the long-term management of both category B waste (low-level and intermediate-level long-lived waste - LILW-LL) and category C waste (high-level waste - HLW and spent fuel). In the absence of a policy decision, the proposed Belgian reference option for disposal of such waste is a GDF in poorly indurated clays, located at a depth of between 200 m and 600 m. Within the framework of the first Safety and Feasibility Case (SFC-1) undertaken by ONDRAF/NIRAS, the organization is updating its former GDF layout, which dates back from 2003. The SFC-1 GDF concept is characterized by a central zone in which shafts, joined by a central connecting gallery, provide two surface connections. On opposing sides of the central gallery, four (two on each side) access galleries branch off to connect the disposal areas for B- and C-waste, respectively. Disposal dead end galleries, 400 m long, branch off perpendicular to the access galleries. Both waste areas will be operated during two separate time frames. The current underground layout has been significantly modified from the previous 2003 layout. The modifications are largely based on several R and D studies with regard to the future operations of the GDF carried out by BGE Technology GmbH in support to ONDRAF/NIRAS. This paper focuses on major operational processes such as waste transport and emplacement. In addition, the current conceptual design of the backfilling and closure concept is presented. Optimization studies on the further development of the operational process are also presented. (authors)

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DOE OSTI2019

Panel Session 3: Featured Country Canada: Management and Disposal of High and Low-Level Waste

This panel featured Senior Executives accountable for the safe management and disposal of most of Canada's radioactive waste liabilities and provided their perspectives on current plans and progress made to date. Topics addressed by the panelists included national policies and programs, the regulatory framework, and actions led by the waste generators and solution implementers to ensure Canada's waste legacy is responsibly managed. Presentations proposed include: 1 - Overview of Canadian Radioactive Waste Policy and Long-Term Waste Management Projects (Dave McCauley, Natural Resources Canada (Canada)); 2 - Featured Country: Canada - National Repository (Laurie Swami, Nuclear Waste Management Organization (Canada)); 3 - Management and Disposal of Ontario Power Generation's Low and Intermediate Level Waste (Lise Morton, Ontario Power Generation (Canada)); 4 - Featured Country: Canada - National Laboratories Liabilities (Richard Sexton, Atomic Energy of Canada Limited (Canada)); 5 - Management and Disposal of High and Low-Level Waste (Mark Lesinski, Canadian Nuclear Laboratories (Canada)); 6 - Disposal in Canada: The Regulatory Perspective (Ramzi Jammal, Canadian Nuclear Safety Commission (Canada))

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DOE OSTI2020

Panel Session 57: US Nuclear Power Plant Waste Management - US LLW Disposal Issues

This panel focused on senior utility managers discussing specific disposal site issues with the disposal site operators. Representatives from each of the operating commercial disposal sites began by presenting an update of their facility, license, and waste acceptance criteria (WAC) followed by a panel discussion in response to audience questions. Panelists with presentations: Current and Emerging US NRC Regulatory Topics (Joe Weismann); WCS Update (Dan Burns); EnergySolutions Clive Facility Support for US LLW Disposal Issues (Vern C. Rogers)

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