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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

A Bottom's-Up Model for Siting and Developing Consent-Based Disposal Solutions for SNF and HLW in the USA - 17332

At the end of 2016, the licensing and continued development of the USA's only candidate HLW-repository since 1987 at the Yucca Mountain (YM) site in Nevada had been on hold since 2010 pending the enactment of enabling legislation for one or more of the following paths forward: 1. Re-start of the YM HLW repository. 2. Consent-based siting and development (S and D) of new HLW-repositories for commingled disposal of commercially- (CHLW) and defense-generated (DHLW) HLW. 3. Consent-based S and D of a repository and/or deep boreholes for DHLW only. Public trust in the implementing and regulating entities and a definitive say in an apolitical S and D process by the directly affected parties (DAPs) are historical imperatives for gaining public acceptance and maintaining sustained support of any or all of them. However, due to the widespread negative legacy currently attributed to past politically-controlled S and D organizations, an even more politically controlled organizational structure and an amorphous, 'consent-based', S and D model like that introduced twice in proposed Senate bills since June 2013 will exacerbate, rather than mitigate, the main root causes to past contentions, lawsuits, delays, and cost-increases. We therefore recommend: 1) Assigning the responsibility for safe disposal of CHLW to an independent, chartered public corporation with requisite subject-matter expertise and adequate financial resources. 2) Enacting a related law that: a. Defines 'consent-based' in measurable terms; b. Assigns irrevocable veto rights to facility host state(s) based upon the majority opinion of its legal residents at pre-determined S and D milestones. c. Requires Congressional approval before the facility can open and close. (authors)

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DOE OSTI2017

Burnt Mountain Alaska RTG Extraction, Transport and Disposal Project - 17359

The Air Force Technical Applications Center (AFTAC), headquartered at Patrick Air Force Base (AFB), Florida, removed excess nuclear material from one of the center's seismic arrays on Burnt Mountain, Alaska, after nearly 15 years of un-operability, and transferred it to a the low-level waste disposal facility at the Nevada National Security Site (NNSS). Ten radioisotope thermoelectric generators (RTGs), were used as a power source by AFTAC at its array 97 kilometers (60 miles) north of the Arctic Circle. Originally placed on Burnt Mountain in 1973, the first RTG was installed to power a single seismometer. Twelve years later, due to the increase in communications equipment and demand for additional power, nine more RTGs were placed at the site. For the next 17 years, the RTGs were operated and maintained by AFTAC's Detachment 460 based at Eielson AFB near Fairbanks, Alaska, and were used because of their high reliability and low maintenance requirements to determine if regional seismic activity was caused by nuclear explosions or naturally-occurring events such as earthquakes, volcanic activity, etc. AFTAC's primary mission is to verify compliance with nuclear test ban treaties. In 1992, a tundra fire encroached on the Burnt Mountain site and damaged some of the data cables. Despite the fact the fire did not impact the generators themselves, it raised public concern among nearby inhabitants about the safety of using radioactive material as a power source at the station. The Air Force, in coordination with multiple agencies and mission partners, made the decision to remove the RTGs and relocate them to NNSS for permanent disposal. (authors)

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DOE OSTI2017

Determining Salinity Recharge Time for Deep Borehole Disposal - 17480

It is generally accepted that the borehole above the disposal zone of a deep borehole disposal must be sealed 'completely' and 'permanently'. By completely it is meant that the seal zone overall must not allow fluids to flow up through it more readily than they could through the surrounding geological barrier. By permanently it is meant that the seal(s) must maintain their function(s) for long enough to satisfy the safety case which could be in excess of 100,000 years. However, designing seals to meet these exacting requirements may be a case of over-engineering because the perturbations in the salinity gradients and density stratification of the groundwater created in and around the borehole during the drilling and operational phases of the borehole would be transient. Darcy flow of groundwater and diffusional flows will re-establish the salinity gradient which is one of the main barriers to the upward flow of fluid through the borehole and surrounding rock, restoring the natural barrier and making the engineered seals redundant. In this paper we address the question of the timescale over which this recharge can be expected to take place. Our methodology involves establishing a mathematical model whose solution gives the time taken for an initial pressure disturbance to reach a steady state and the migration rates of brines resulting from this pressure field. We discuss the model, its assumptions and the solutions, both analytical and numerical. (authors)

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DOE OSTI2015

The Cires facility in Morvilliers: from a VLL waste disposal facility to the development of industrial activities - 15252

The disposal facility of CIRES for very low level wastes was designed to provide safe and cost effective services to waste generators, in particular for decommissioning works. The facility could significantly increase waste annual deliveries to meet waste generators' needs and accommodate large disused components as PWR steam generators after decontamination. However an anticipated saturation of its capacity is foreseen as needs for disposal has doubled since its start-up. The geometry of the cells was optimized and the technical capacity of the repository is presently by 40% above its licensed capacity. Saturation has been delayed; however a new facility will be necessary by 2030 and other waste management options are to be considered as recycling of metallic wastes or crushed concrete rubble. CIRES facility also became Andra's industrial platform for the management of institutional wastes. A grouping and a storage facility have been built and a new processing facility should start up in 2016. (authors)

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DOE OSTI2015

KAERI Underground research tunnel (KURT) - phase II activities for HLW disposal technology development in Korea - 15253

Phase I construction of the KAERI Underground Research Tunnel (KURT), a small-scaled underground research facility, was completed in November 2006. Since then various in-situ tests and experiments at KURT for phase I have been carried out to develop safe and reliable disposal techniques for high-level radioactive waste in a deep geological formation. The KURT extension project was approved by the Korean government in 2012 and the design of the tunnel layout and construction methods were decided by early 2013. Site investigation and installation of a monitoring system for the extension were completed by Oct. 2013. The construction activity was started from December 2013 and will be completed by the end of 2014. Phase II experiments in KURT will be carried out for the next 10 years. KURT continues to play a significant role in validating the safety and feasibility of a deep geological disposal system in the research program in Korea. (authors)

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DOE OSTI2015

Centre de la manche disposal facility after ten years of institutional control - 15255

Centre de la Manche disposal facility is the first French surface disposal facility for low and intermediate level short lived radioactive waste. It has been operated for 25 years, from 1969 to 1994. The facility was licensed for the institutional control period in 2003. As there were significant changes in the design of vaults or in waste acceptance criteria during the 25 years of operation, it was decided to implement a capping system including a bituminous membrane that would be able to sustain strains that might be caused by the settlement of waste packages in the eldest parts of the facility, where conditioning modes were different than those as presently practiced. In 2008 Andra submitted to ASN, the regulatory body in France, a file related to the safety of the facility including a study of the opportunity to modify capping system. Andra's project was to improve long term watertightness and to stabilize the sides of the cover by smoother slopes through a progressive approach. This file was completed in early 2015 by a progress report providing in particular results on studies related to the durability of the bituminous membrane. They take into account periodical measurements performed on samples of the membrane extracted from the capping system and studies performed on the phenomenology of ageing of the membrane. These data support the strategy of improvement of the capping system developed by Andra in order to achieve a more passive surveillance. (authors)

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DOE OSTI2016

Deep Borehole Disposal: Options, Issues and Challenges - 16250

Different versions of deep borehole disposal vary in approach and detail and the differences raise issues and create options that need to be considered in the design of any practical implementation. Among the areas for which significant options exist are the size and depth of the disposal zone; container materials and design; the method and strategy for waste package deployment; filling of the annuli around the waste packages and the final sealing of the borehole. The options for these and other areas are discussed with a focus on their advantages and disadvantages and some conclusions reached that could provide guidance for the practical application of the concept. One particularly significant point is that the integrity of the final borehole seal(s) may not be required to survive for as long as is widely believed. (authors)

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DOE OSTI2018

Evaluating the Chemical Resistance of Salt-stone Disposal Unit (SDU) Concrete and Polymeric Coatings - 18494

Salt-stone Disposal Units (SDUs) are multi-million liter concrete structures that are used at the Savannah River Site (SRS) for the permanent disposal of low-activity salt solution incorporated in a cementitious grout matrix, termed salt-stone. The major chemical constituents of the salt solution include sodium, aluminum, nitrate, nitrite, hydroxide, carbonate, and sulfate. The potential exists for the SDU interior to be chronically exposed to these corrosive constituents resulting in deleterious reactions and physical damage. Sulfate attack is an example of such an interaction whereby aqueous sulfates may penetrate the concrete, and react with hydration products in the cured concrete to form expansive phases that can cause excessive strains and cracking. Recently constructed SDUs have utilized sulfate-resistant Type V cement and polymeric coatings to minimize the potential impacts of SDU concrete exposure to the highly caustic (pH > 13) salt solution. Not only must the concrete and coatings exhibit high resistance to the caustic salt solution but they are also subjected to above ambient temperatures due to the exothermic nature of the grout hydration reaction. As such, both the SDU concrete and the coatings need to be tested with respect to stability in the aforementioned chemical and thermal environments. Two primary investigations were considered in this work. The first was to evaluate the resistance of two previously used epoxy coatings (Hempel Versiline TL-45 S Novolac and EC-66 elastomeric epoxies) to chemical attack from a simulated salt solution. In addition, a third coating was included in the study, a poly-urea coating (Sherwin Williams Envirolastic AR425) that may be considered as an alternative to the epoxy coatings on future SDUs. Each coating was applied to concrete cylinders (actual SDU 6 test cores) and subsequently exposed to salt-stone, or full and half strength caustic salt solution; 50% dilution was considered since salt-stone processing involves addition of flush water to the SDUs, which is expected to dilute any residual salt solution or bleed water in the SDU. Exposure testing was conducted at 68 deg. C for 1,000 hours followed by ambient exposure to provide a full exposure time of approximately 90 days. It is important to note that evaluation criteria for the coated materials were only visual in nature. Other than coating discoloration, which was limited to the surfaces, no other visual indications of reactivity between the three coatings and any of the exposure mediums were observed. Cross-sectioned samples indicated no through-thickness coating penetration or reaction, and showed no signs of delamination. The second investigation was also performed to determine if SDU concrete without a polymeric barrier would resist ingress and reaction with salt solution at the elevated temperature. Again, only slight discoloration of the concrete surfaces was observed after the 90-day exposure test irrespective of the salt solution concentration. A requirement of structural concrete in the SDUs is that it possesses a minimum compressive strength of 42 MPa (6,000 psi). The average compressive strength of samples exposed to the full-strength salt solution was recorded at 68 MPa compared to 66 MPa for the unexposed samples thus indicating that the exposure conditions considered in this study were not detrimental to the concrete strength. (authors)

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DOE OSTI2019

Scenario Development: Proposal of a Methodology for Different Host Rocks and Disposal Concepts - 19007

Scenario development is an essential part of the assessment of the long-term safety of a repository for radioactive waste. The new act on site selection in Germany in 2017 requires that salt, clay and crystalline rock are studied as possible sites for repositories. So far, a comprehensive methodology for scenario development has been developed only for a site in salt rock in Germany within the Preliminary Safety Analysis (VSG). The question arose whether this methodology is transferable to other host rocks and disposal concepts and which modifications may be necessary. The transferability was shown in the project ANSICHT for clay rock sites while introducing some modifications of the methodology. This project studied the transferability of crystalline rock sites, however, there is no suitable safety and disposal concept or even a generic site yet. To study the transferability, initial barriers and FEP for different concepts were selected and the first steps of the methodology for crystalline rock were applied and discussed. It was concluded that the definition of barriers as containment providing rock zone (CPRZ) is difficult but important for the application of the methodology. Concepts for crystalline rock can foresee a CPRZ within the host rock or above. If the concept is using engineered barriers only and no CPRZ, the number of initial barriers is low. This will subsequently lead to a more complex scenario development since long FEP chains have to be considered. Based on the discussion so far, the transferability of the methodology seems to be feasible in general. (authors)

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DOE OSTI2019

Treatment of Uranium Catalyst Waste for High Volume Reduction of the Final Waste to be Disposed - 19023

A large volume of problematic radioactive waste of spent uranium catalyst, approximately 7,000 drums was generated by a chemical company in Korea. The spent uranium catalyst has since been stored onsite awaiting a management strategy that is to minimize the volume/cost requirements for final disposal of the uranium-bearing waste. This work developed for the first time a process to greatly reduce the waste volume to be disposed while the secondary wastes generated from the process being released to the environment are controlled to meet the discharge criteria in Korea. (authors)

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DOE OSTI2019

Implementation of Research and Development (R and D) Results in the Design of Liner System for the Near Surface Disposal Facility (NSDF) - 19089

Canadian Nuclear Laboratories (CNL) proposes to develop a Near Surface Disposal Facility (NSDF) at the Chalk River Laboratories (CRL) site in Ontario, Canada for disposal of CNL's Low Level Radioactive Waste (LLW) and other suitable wastes meeting the Waste Acceptance Criteria (WAC). The NSDF's Engineered Containment Mound (ECM) includes base liner and final cover systems. These liner systems are designed to perform effectively for a total of 550 years. The specified geomembrane in the NSDF detailed design is 2 mm thick High Density Polyethylene Geomembrane (HDPE GMB) double sided textured and white surface. CNL's approach to collaborate with Subject Matter Expert (SME) consultants and contractors, a Canadian university, and industry has enabled the NSDF to incorporate current best design practices, particularly for the design of the ECM's liner systems. This paper describes the HDPE GMB testing program and how the results of the state-of-the-art research have been utilized in the design of the NSDF's liner system and in selection of the best candidate materials to strengthen the confidence that the required service-life will be met. The testing program includes index properties and long-term performance evaluation tests of the five candidate HDPE GMBs using leachate simulant comparable to expected NSDF leachate and an index simulant used for testing many GMBs. The results of the tests are used as the basis to assess expected HDPE GMBs long-term performance. The expected long-term performance is applied as the key consideration for the final selection of the HDPE GMB in the NSDF project. Preliminary results of the testing program indicate that an expected service-life of 550 years will likely be met by the candidate HDPE GMB. (authors)

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DOE OSTI2019

Alternate Packaging Options for Remote-Handled Transuranic Waste Disposal at WIPP - 19093

Sandia National Laboratories/New Mexico (Sandia) began a remote-handled (RH) transuranic (TRU) repackaging campaign two weeks before the Waste Isolation Pilot Plant (WIPP) shutdown in February 2014. Since a contract with Nuclear Waste Partnerships (NWP), the WIPP Management and Operation (M and O) contractor, was already in place for certified visual examination (VE) and dose-to-curie (DTC) support, repackaging continued and was completed in October 2015. Twenty-five 55-gallon drums of RH TRU waste were packaged, awaiting certification and shipment to WIPP. However, in February 2017 at the National TRU Program (NTP) Corporate Board meeting, Sandia learned that RH TRU waste normally transported in removable lid canisters (RLCs) and 72-B casks was not being accepted for disposal when WIPP re-opened after the shutdown. One option, shielded container assemblies (SCAs), was available and approved for RH TRU waste disposal at the WIPP. Sandia made the decision to pursue the use of SCAs. The use of SCAs allow RH TRU waste to be shipped as contact-handled (CH) in HalfPACTs, emplaced on the floor of the WIPP instead of in boreholes in the walls, if the dose rate is less than 200 millirem/hour on contact. The RH TRU waste remains on the WIPP inventory as RH. (authors)

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DOE OSTI2019

Near Surface Disposal Facility Iterative Assessment - 19199

Canadian Nuclear Laboratories (CNL) is proposing the construction of a Near Surface Disposal Facility (NSDF) on the Chalk River site, in order to dispose of legacy low level waste and anticipated building debris from future decommissioning. A Performance Assessment is being conducted, using an iterative process, to assess the short and long term effects of this facility. Three iterations have already been completed, each building on the last, and a further iteration is underway to improve on the current results. This paper discusses the iterative process taken in these assessments. (authors)

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DOE OSTI2019

Disposal of a pretreated oil sludge by the cementation method

Radioactive oil sludge is generated in oil production rigs worldwide and in large quantities. However, in Brazil, there is no disposal route or well-defined treatment option for this waste. This sludge is classified as TENORM due to the presence of Potassium-40 and the radionuclides of the natural decay chains of thorium and uranium. The management of this radioactive waste has been in situ packaging on the offshore platforms, followed by its transport to storage facilities onshore. Long term storage is problematic due to the high content of hydrocarbons, sulfur and water, which generates the toxic gas H{sub 2}S and the corrosive sulfuric acid. Ozonation, an advanced oxidation process (AOP) can be considered an attractive option of treatment, and followed by cementation can improve safety in long-term storage. This work aims at investigating if the ozone process was able to enhance the immobilization capacity of oil sludge. Oil sludge from different drums and mixed oil sludge (obtained by mixing equal parts of each drum) were analyzed by ICP. Solidification of oil sludge with Portland cement enhances safety of the waste disposal. In addition, ozonation treatment is efficient in the degradation of organic compounds, increasing the resistance of the solidified material.

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DOE OSTI2020

CSA, the French LILW Disposal Facility: Taking Stock of the 30 years' Operating Experience - 20009

French Andra's currently operational LILW repository, Aube disposal facility, is almost 30 years old. From the beginning, the repository has benefited from the lessons learned from the first disposal facility, the CSM. It has nevertheless continued to evolve, to improve and to adapt, seeking to gain in efficiency, safety and cost optimization. This is a look at what has changed at the CSA since 1992 - and the effect these changes had on its operating practices, construction principles and the entire management organization. (authors)

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DOE OSTI2024

Human Health Risk Assessment for Improper Landfill Disposal of End-of-Life CdTe Modules

The present work is a continuation of the 2020 IEA PVPS Task 12 Human Health Risk Assessment Methods for PV Part 3: Module Disposal Risks. The 2020 report performed a human health risk assessment (HHRA) for disposal of a cadmium telluride (CdTe) PV module in an unlined landfill, focusing solely on risks from cadmium. This study extends the 2020 HHRA on CdTe PV, analyzing eleven constituent elements: Cd, Se, Te, Cu, Si, Cr(III), Mo, Sn, Zn, Ni, and Al. The present HHRA was performed through two methods: utilization of the U.S. Environmental Protection Agency's (USEPA) Delisting Risk Assessment Software (DRAS V.4.0) on eight exposure pathways for cancer risk and non-cancer hazards; and comparison of exposure point concentrations to federal standards for groundwater, surface water, air, and soil exposure pathways. Cancer risks and non-cancer hazards posed by elemental leaching through all evaluated exposure pathways, using both methods, were found to be several orders of magnitude below USEPA health-protective thresholds. Cadmium exhibited both the highest risks and lowest uncertainty considering data availability on chemical content, leachate, and federal screening levels.

CdTe↗
DOE OSTI2017

Sewage sludge disposal strategies for sustainable development

The main objective of the present review is to compare the existing sewage sludge management solutions in terms of their environmental sustainability. The most commonly used strategies, that include treatment and disposal has been favored within the present state-of-art, considering existing legislation (at European and national level), characterization, ecotoxicology, waste management and actual routs used currently in particular European countries. Selected decision making tools, namely End-of-waste criteria and Life Cycle Assessment has been proposed in order to appropriately assess the possible environmental, economic and technical evaluation of different systems. Therefore, some basic criteria for the best suitable option selection has been described, in the circular economy “from waste to resources” sense. The importance of sewage sludge as a valuable source of matter and energy has been appreciated, as well as a potential risk related to the application of those strategies. - Highlights: • Environmental sustainability in sewage sludge management. • Investigation of eco-innovations in wastewater treatment. • Assessment of ecological consequences of sewage sludge disposal.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Thermal loading effects on chalk hydromechanical behavior for nuclear waste disposal

Safe disposal of heat-generating nuclear waste depends on host rock stability under thermal, hydrological, and mechanical stresses. This study investigates the effect of thermal loading on mechanical behavior of the shallowly buried Ghareb formation chalk through triaxial and hydrostatic constant strain rate and creep tests at temperatures up to 100 ˚C and effective pressures up to 20.7 MPa. Experimental results show that thermal loading reduces the elastic moduli of chalk by 50–75%, and a transition occurs above 60 ˚C where creep rates increase rapidly. Water saturation nearly doubles the thermally induced strain compared to dry conditions and strongly decreases material rigidity. Thermal loading also leads to significant pore pressure increases under undrained conditions and leads to reductions in the apparent permeability during drained conditions. Laboratory experimental data were used to parameterize and develop a preliminary constitutive model for predicting future deformation during repository operations in the Ghareb. The strongly coupled effects – mechanical weakening, fluid pressure fluctuations, and permeability modification – demonstrate that elevated repository temperatures will have a pronounced effect on the near field Ghareb behavior during waste disposal operations. The findings indicate that the coupled interactions must be considered in predictive models and repository design to ensure long-term nuclear waste isolation and safety.

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