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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Long-Term Performance of Reference Electrodes in Alkaline Radioactive Waste Storage Environments

Accurate measurements of corrosion potential are important for assessing the likelihood of internal localized corrosion and stress corrosion cracking of carbon steel tanks used for storing radioactive wastes. Reference electrodes in underground radioactive waste storage tanks are challenging to deploy, and more difficult to extract and replace frequently due to radiological exposure and disposal constraints. Hence, electrodes that exhibit stable performance over long periods of immersion in these waste environments are desirable. The present study evaluates the stability of reference electrodes used in radioactive waste storage tanks over a much longer period than previously studied. Long-term tests on Ag/AgCl and Hg/HgO reference electrodes were performed in nonradioactive simulants formulated from wastes stored at the Hanford site. Electrode degradation, which was studied by various in situ and ex situ evaluation techniques, was correlated to changes in electrode fill chemistry from waste intrusion via the porous frit junction. An intentional contamination study was performed to better understand and predict contamination effects on electrode potential drift.

Materials Science↗
DOE OSTI2020

Spent Nuclear Fuel Storage and Radioactive Waste Disposal in the United States: A Law and Policy Analysis - 20302

While Congress plays political football, spent nuclear fuel continues to sit in de facto interim nuclear waste storage sites throughout the country. This ad hoc approach - if it can even be called an approach - to nuclear waste management is in no one's best interests, because of financial, safety, environmental, and national security concerns with the status quo. Senate leadership had asserted that an up-or-down vote on the Yucca Mountain Project would take place in September or October 2019, but that did not occur. Rather, a conference bill was agreed to, and it provided that, although the nuclear program should receive some funding, funding was not made available for centralized interim storage ('CIS') or the Yucca Mountain Project. The President's FY2021 Budget Request does not contain any proposed funding for the Yucca Mountain Project ('the Project'). This paper will discuss the implications of that process, both for the Project itself and for the U.S. nuclear waste program more generally. In order to provide context for the current situation, this paper will begin by chronicling the history of U.S. nuclear waste management, from the passage of the Nuclear Waste Policy Act of 1982 and to the present day. It will discuss the roles of the U.S. Department of Energy, the Nuclear Regulatory Commission, federal and state political delegations, and the nuclear energy industry. The paper will then identify key themes that can be expected to affect the future of nuclear waste management in the United States. For example, it will consider whether development of additional CIS facilities is a viable short- to medium-term solution. CIS facilities may relieve immediate pressure at decommissioned or soon-to-be-decommissioned nuclear power plants; but with that pressure partially alleviated, support for building a long-term repository may be reduced. It will also discuss opposition by the State of New Mexico and others to the proposed New Mexico CIS project, based not only on siting concerns but also whether it might become a de facto repository, and whether the State of Texas and others may also be opposed, for similar reasons, to the proposed CIS facility in Texas. Additionally, the paper will examine consent-based siting and its implications for Nevada and other states that are potential hosts for spent nuclear fuel storage and disposal facilities. Further, if the Project is not a politically viable solution, the paper will examine whether it is now time for serious consideration of an alternate location for a permanent repository, as well as consideration of other options entirely, such as deep geologic disposal. The paper will conclude by looking ahead to the 2020 elections. It will describe the positions of candidates (particularly Presidential candidates) on spent nuclear fuel storage and disposal options, without advocating for any particular candidate or political party. Perhaps in 2020, we will at least see a start to a solution to the seemingly intractable problem of nuclear waste management in the United States. (authors)

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

Determination of Erosion/Corrosion Rates in Hanford Tank Farms Radioactive Waste Transfer System Pipelines

The twenty-eight double-shell underground radioactive waste storage tanks at the U. S. Department of Energy’s Hanford Site near Richland, WA are interconnected by the Waste Transfer System network of buried steel encased pipelines and pipe jumpers in below-grade pits. The pipeline material is stainless steel or carbon steel in 51 mm to 152 mm (2 in. to 6 in.) sizes. The pipelines carry slurries ranging up to 20 volume percent solids and supernatants with less than one volume percent solids at velocities necessary to prevent settling. The pipelines, installed between 1976 and 2011, were originally intended to last until the 2028 completion of the double-shell tank storage mission. The mission has been subsequently extended. In 2010 the Tank Operating Contractor began a systematic evaluation of the Waste Transfer System pipeline conditions applying guidelines from API 579-1/ASME FFS-1 (2007), Fitness-For-Service. Between 2010 and 2014 Fitness-for-Service examinations of the Waste Transfer System pipeline materials, sizes, and components were completed. In parallel, waste throughput histories were prepared allowing side-by-side pipeline wall thinning rate comparisons between carbon and stainless steel, slurries and supernatants and throughput volumes. The work showed that for transfer volumes up to 6.1E+05 m 3 (161 million gallons), the highest throughput of any pipeline segment examined, there has been no detectable wall thinning in either stainless or carbon steel pipeline material regardless of waste fluid characteristics or throughput. The paper describes the field and laboratory evaluation methods used for the Fitness-for-Service examinations, the results of the examinations, and the data reduction methodologies used to support Hanford Waste Transfer System pipeline wall thinning conclusions.

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

Detection and Mitigation of Hanford Site Radioactive Waste Tank Surface Water Intrusion - 16396

The last single-shell underground radioactive waste storage tanks at the U.S. Department of Energy's Hanford Site, near Richland, WA, were removed from service in November, 1980. At that time the single-shell tanks contained 153,300 m{sup 3} (40.5 million gallons) of waste, including 34,400 m{sup 3} (9.1 million gallons) of liquids. Subsequently the Interim Stabilization Program and Waste Retrieval/Closure Project have removed 24,600 m{sup 3} (6.5 million gallons) of liquid from the tanks to reduce the potential for leakage to the environment. After interim stabilization, each tank was isolated by cutting and capping waste transfer lines, filling drains with grout, and covering likely surface water entry points. The minimum expected lifetime for the isolation features was 20 years, consistent with planned retrieval of all single-shell tank wastes by 2018. Since then the retrieval completion date has been extended. In 2011 the Tank Operating Contractor began a systematic review of the aging isolation barriers to determine if surface water was entering the single-shell tanks. This paper summarizes the results of the 2011 - 2015 activities including single-shell tank inspection results, methodologies used to identify intrusions and waste leaks masked by intrusion, and eventual deployment of a prototype forced ventilation exhauster in 2015 to evaporate water intrusion pools on the waste surface. Further efforts to limit water intrusion, including deployment of surface barriers, are discussed. (authors)

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

Sealing Shales versus Brittle Shales: A Sharp Threshold in the Material Properties and Energy Technology Uses of Fine-Grained Sedimentary Rocks

Fine-grained sedimentary rocks (shale and mudstone) play important roles in global CO 2 abatement efforts through their uses in carbon capture and storage (CCS), radioactive waste storage, and shale gas extraction. These different technologies, however, rely on seemingly conflicting premises regarding the sealing properties of shale and mudstone, suggesting that those rocks that lend themselves to hydrocarbon extraction may not be optimal seals for CCS or radioactive waste storage, and vice versa. In this paper, a compilation of experimental data on the properties of well-characterized shale and mudstone formations is used to demonstrate that clay mineral mass fraction, X clay , is a very important variable the controls key material properties of these formations and that a remarkably sharp threshold at X clay ~ 1/3 separates fine-grained rocks with very different properties. Finally, this threshold coincides with the predictions of a simple conceptual model of the microstructure of sedimentary rocks and is reflected in the uses of shale and mudstone formations for CCS, radioactive waste storage, and shale gas extraction.

58 GEOSCIENCES↗
DOE OSTI2019

NPP SCCs Based Deregulation Process Application Case Design with Internal Block Diagram of SysML - 19237

- It will be possible to group the radioactive wastes from the perspectives on Systems, Structures and Components (SSCs). This paper covers systematic approaches for deregulating grouped decommissioning wastes. SSCs decomposition structure, mass flow of decommissioning waste, sequence and storage time estimation method for deregulation, and interrelationship between them are presented. The expected benefit is the ability possibly to apply deregulation process to SSCs because SSCs breakdown structure is connected with mass flow of decommissioning waste, deregulation option, and storage time. This allows for the application of deregulation strategies and processes on SSCs basis and can enhance the rationale and traceability of the waste grouping. The sequence for deregulation reflects the logic of ensuring that radioactive nuclides meet self-disposal criteria and storing or disposing radioactive wastes if not met. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

AVANTech's Advanced Polymer Solidification for Radioactive and Mixed Waste Stabilization: Case Studies - 18571

This presentation describes recent developments in polymer technology, as well as summarizes several applications and the history of process improvements that simplify the process and improve the efficiency for stabilizing low and intermediate level radioactive and mixed radioactive/hazardous wastes. Polymer technology has been used successfully since the early 1990's to solidify and stabilize radioactive and mixed hazardous/radioactive waste at United States (US) Department of Energy (DOE), US Department of Defense (DOD), United Kingdom government sites, and at commercial nuclear power plants. It is an effective, efficient, and economical means of preparing waste for storage and disposal. Recently, polymer solidification has been combined with other waste pretreatment technologies, such as evaporator concentrate drying, to further enhance volume reduction and packaging efficiency. This presentation reviews applications of the technology and identifies waste streams where polymers have advantages over cement, vitrification, and other stabilization processes. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Impacts of Crust Properties on the Waste Feed Delivery of Hanford Tanks with Flammability Concerns - 18161

Mitigation of flammability concerns within Hanford waste tanks is essential to Safe Storage and Waste Feed Delivery sub-functions of the River Protection Project Mission. The tanks that have a higher propensity for the generation, retention, and release of flammable gas are considered Waste Group A tanks. Group A tanks include 241-SY-103, 241-AN-103, 241-AN-104, 241-AN-105, and 241-AW-101. Successful mitigation of flammability concerns in these tanks is necessary, as they are critical to the completion of the River Protection Project Mission as indicated in the Integrated Waste Feed Delivery Plan. The benchmark for examination of tank flammability issues is 241-SY-101. Studies of Tank 241-SY-101 gas release events showed that the mechanism of gas retention and release was highly dependent on the volume and configuration of a floating crust layer. Beginning in 1993, 241-SY-101 underwent water additions and mixer pump operations resulting in dissolution of the crust. These efforts mitigated the flammability concerns of the tank. A similar mitigation approach was recommended for Tank 241-SY103 and is recommended for the other Waste Group A tanks. However, this recommended mitigation will be more or less effective based on the expected thickness of the crust present in each of the Group A tanks. Considerations of flammable gas generation and release mechanisms were essential in the development of a successful mitigation strategy for Tank 241-SY-101, and will be essential in the development of future mitigation strategies. Because crust properties are difficult to measure, tank surface level trends and current temperature profiles are evaluated to understand crust properties. 241-AN-103 and 241-AW-101 are the only two tanks with a net increase in surface level, indicating a higher generation and retention of flammable gas. Additionally, these are the two tanks with the thickest crusts, which causes both a higher retention of gas and a reduced evaporation rate. Given the current temperature profile, crust thickness for 241-AW-101 was re-evaluated to be 145 cm (57 in) ± 30 cm (12 in) which is different from its historic value. This gives 241-AW-101 the thickest crust, second only to 241-SY-101 prior to mitigation. The crust thickness for 241-AN-103, however, retains its historic value of 89 cm (35 in) ± 16 cm (6 in). These crust properties suggest modifications to the mitigation strategy are needed for each tank. For example, 241-AN-103 and 241-AW-101 will require additional water to dissolve the crust layer before flammability concerns are mitigated and further operations could commence. Implementation of the modified mitigation strategies will mitigate flammability issues and help fulfill the Safe Storage and Waste Feed Delivery sub-functions of the River Protection Project Mission safely and efficiently. (authors)

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

History and Status of DoE's Standardized Canister - 19657

The U.S. Department of Energy (DOE) is responsible for managing spent nuclear fuel (SNF) currently in its possession, as well as SNF that will come into its possession in the future. DOE will rely upon the standardized canister to confine radionuclides and precluding the moderator in order to ensure safe, long-term management and disposition of SNF in its possession. This strategy helps minimize characterization costs (i.e., funds and exposure) and other technical challenges associated with the traditional approach of relying on fuel-specific properties to demonstrate compliance with the regulator. The use of the standardized canister offers the following benefits: - The standardized canister design is complete. It has been tested under a variety of drop and accident scenarios and was subsequently licensed under 10 CFR 72 as a storage system as part of the Foster Wheeler Environmental Corporation (FWENC) Facility. It is also part of the license submittal for Yucca Mountain. - There is high confidence that the standardized canister design can be stored within commercially-available storage casks and licensed as part of a transportation-system package. - A robust standardized canister simplifies accident analyses and does not rely on characterization of the contained waste. This simplifies safety analysis, provides a greater level of confidence with stakeholders and reduces cost and risk. - A common design for the associated packaging, closure, and loadout facilities results in significant savings. - The DOE standardized canister would simplify design efforts, procurement, and fabrication. - Standardizing handling activities and associated training, procedures, equipment, and tooling leads to enhanced safety and surety of operations. The standardized canister is the preferred package for these materials. It withstood scrutiny by the Yucca Mountain Repository License Application, the Nuclear Regulatory Commission's (NRC) Advisory Committee on Nuclear Waste, the Nuclear Waste Technical Review Board, an American Society of Mechanical Engineers peer review, and the FWENC storage license application. This evaluation summarizes and documents the status of the design and rationale for the DOE standardized canister, and outlines remaining needs before deployment. In addition, it discusses the factors that have the potential to influence storage, transportation, and disposal of DOE SNF. (authors)

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

Developing Materials for Extreme Environments and Their Use in Nuclear Waste Canisters and Reactors - 20559

The paper focuses on the development of materials which can be utilized in extreme industrial environments. The paper discusses the advancement of materials and their application in components which are utilized in extreme industrial environments as such that of the nuclear field and especially in the nuclear waste field. Nuclear power plants have become an indispensable part of the electricity generation, medical, food processing and many other industries. Though burning small amount of fuel as compared to conventional power plants, they also create waste which is not easy to handle as other types of wastes. The nuclear waste sitting at the bottom of spent fuel tanks around the globe has raised public concerns on how it will be dealt with. Europe has started to give an answer by working on geological repositories. Though till yet, waste has been cooled in spent fuel tanks and after processing, is precisely placed in nuclear waste canisters and casks and transported to sites across the country for further cooling and storage. Though in all this process there had been a great deal of advancement on the type of casks and canisters used and the processes for transporting nuclear material and waste. Often reports about radioactive material leakage, moisture content inside barrels etc. has surfaced. Be it official or unofficial report, there seems a technical failure on how the nuclear waste has been stored and placed at facilities around the globe. The other aspect of this material development is to be beneficial for nuclear reactors. As the technology gets advanced, nuclear reactors change their titles from Gen II to Gen III and so on. The new fleet of upcoming reactors will be exceptionally safer, reliable and more efficient. But these benefits will also bring drawbacks with them. As these reactors will operate at high temperature (above 800 degree Celsius) they also ask for advancement in materials used in the reactor core, fuel used, reactor control etc. The paper tries to answer such concerning questions. The work shows the study done on different material that can be better candidates for extreme environments. (authors)

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

CEA decommissioning and clean-up activities legacy waste management and lessons learned - 15506

The CEA has generated radioactive waste in both liquid and solid form for more than 50 years within the scope of its R and D, clean-up and dismantling programs. The vast majority of the waste produced is transferred to disposal centers in approved waste packages. Nonetheless, a large quantity of legacy waste still remains in ageing facilities in which the storage conditions are sometimes no longer satisfactory with respect to the safety requirements that are constantly evolving. As part of a broad clean-up and dismantling process focusing on these ageing facilities managed by the CEA, the top priority is to shut down nuclear activities on two symbolic sites: Grenoble and Fontenay-aux-Roses, which are both located in a dense urban environment. After about ten years of dismantling, the nuclear facilities on the Grenoble site are on their way to be completely decommissioned in the regulatory sense of the term. Furthermore, the radwaste issue on this site has raised no specific problems, though it did require developing innovative and sometimes costly waste outlets. The older Fontenay-aux-Roses site is where the first experimental research on minor actinide separation took place. The facilities on this site have reached a stage in dismantling which necessitates the recovery of irradiating legacy waste containing alpha, beta and gamma emitters. The transfer of this waste to interim storage centers more than 600 kilometers away is a decisive factor in reducing the site's nuclear source term and in ensuring the satisfactory progress of the dismantling operations. This paper details the issues raised by the recovery of legacy waste, which requires greater characterization to better understand its radiological and chemical status. This waste also requires better characterization to meet the storage requirements of new sites designed for storage periods exceeding 50 years prior to its final disposal in a deep geological repository. The issue of transporting waste on public roads is specifically covered, along with the strategy defined to securely transfer all legacy waste resulting from the CEA's very diverse R and D programs. Emphasis is placed on finding the right balance between collecting the necessary data on the waste to be transported, ensuring the reconditioning of this waste so it can be transported safely, and maintaining an efficient industrial-scale waste transfer process to limit the lead times and costs related to legacy waste recovery operations. (authors)

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

Delayed Gamma-Ray Spectroscopy for Non-Destructive Assay of Nuclear Materials

High-­energy, beta-delayed gamma-­ray spectroscopy is a potential, non-­destructive assay techniques for the independent verification of declared quantities of special nuclear materials at key stages of the fuel cycle and for directly assaying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Other potential applications include determination of MOX fuel composition, characterization of nuclear waste packages, and challenges in homeland security and arms control verification. Experimental measurements were performed to evaluate fission fragment yields, to test methods for determining isotopic fractions, and to benchmark the modeling code package. Experimental measurement campaigns were carried out at the IAC using a photo-­neutron source and at OSU using a thermal neutron beam from the TRIGA reactor to characterize the emission of high-­energy delayed gamma rays from 235 U, 239 Pu, and 241 Pu targets following neutron induced fission. Data were collected for pure and combined targets for several irradiation/spectroscopy cycle times ranging from 10/10 seconds to 15/30 minutes.The delayed gamma-ray signature of 241 Pu, a significant fissile constituent in spent fuel, was measured and compared to 239 Pu. The 241 Pu/ 239 Pu ratios varied between 0.5 and 1.2 for ten prominent lines in the 2700-­3600 keV energy range. Such significant differences in relative peak intensities make it possible to determine relative fractions of these isotopes in a mixed sample. A method for determining fission product yields by fitting the energy and time dependence of the delayed gamma-­ray emission was developed and demonstrated on a limited 235 U data set. De-­convolution methods for determining fissile fractions were developed and tested on the experimental data. The use of high count-­rate LaBr 3 detectors was investigated as a potential alternative to HPGe detectors. Modeling capabilities were added to an existing framework and codes were adapted as needed for analyzing experiments and assessing application-­specific assay concepts. A de-­convolution analysis of the delayed gamma-­ray response spectra modeled for spent fuel assemblies was performed using the same method that was applied to the experimental spectra.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Chemo-chromic Pd-V{sub 2}O{sub 5} Sensors for Passive Hydrogen Detection in Nuclear Containments - 18268

The ability to detect and monitor hydrogen gas efficiently in process and storage facilities, handling nuclear material, is crucial to ensuring their safety. The accumulation of hydrogen gas, above the lower flammable limit (LFL), in a nuclear waste containment is a concern since it creates the potential for a hydrogen-air explosion to occur, which could lead to a loss of containment and result in the uncontrolled release of radioactive material into the surrounding environment. The events that took place at Fukushima Daiichi Nuclear Power Plant highlighted the vulnerability of conventional hydrogen detection to extreme events, where power may be lost. In the present work, chemo-chromic hydrogen sensors have been fabricated, using transition metal oxide thin films, to provide eye-readable detection systems that would be resilient to plant power failure. Vanadium oxide (V{sub 2}O{sub 5}) films were prepared on quartz glass substrates by sol-gel deposition and sensitized with a palladium (Pd) catalyst, deposited by electron beam evaporation. When exposed to hydrogen, the Pd catalyst dissociates H{sub 2} to H atoms, which diffuse into the V{sup (V)}{sub 2}O{sub 5} forming a hydrogen-vanadium metal bronze, H{sub 2}V{sup (III)}{sub 2}O{sub 5}, resulting in a noticeable colour change from orange to dark green. To assess their viability for nuclear safety applications, these sensors have been irradiated to total doses between 5 and 250 kGy using a Co-60 gamma isotope irradiator. The results suggest that gamma irradiation, at the levels examined, has an effect on the initial colour of the V{sub 2}O{sub 5} and Pd-V{sub 2}O{sub 5} thin films with decreased transmittance above 540 nm. The orange starting colour darkened and developed a green tone, with the degree of colour change depending on the applied total dose. Changes in surface morphology and characteristics have been examined by using Scanning Electron Microscopy (SEM) and Raman spectroscopy. High level (250 kGy) gamma radiation exposure begins to produce surface degradation on V{sub 2}O{sub 5} thin films; however this behaviour is not observed for films that are also coated with palladium. Chemo-chromic properties of both un-irradiated and irradiated Pd-V{sub 2}O{sub 5} thin films were determined by examining their optical transmittance, using UV-vis spectroscopy, under exposure to a 4% H{sub 2}-N{sub 2} gas mixture. Exposure to gamma radiation has been found to have negligible effect upon colour change behaviour after 30 minutes exposure to hydrogen gas. The results suggest that the thin film V{sub 2}O{sub 5} sensitised with Pd is a plausible technique for application in the monitoring of hydrogen gas in low-level gamma radiation environments. (authors)

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

Sludge Removal: Success and Partnership with T Plant - 20510

U.S. DOE contractor CH2M Hill Plateau Remediation Company (CHPRC) has safely and efficiently managed the removal of highly radioactive sludge from the 105-K West Reactor fuel storage basin (105- KW Basin) near the Columbia River. In mid-September 2019, sludge retrieval was completed after 21 storage containers were safely loaded with highly radioactive sludge and transported approximately 13 miles from the 105-KW Basin to T Plant, located in the 200 West Area on the Central Plateau of the Hanford Site. Sludge removal represents the last major source term reduction necessary before the K West Reactor and fuel storage basin can transition to closure activities in preparation for final deactivation and demolition. The technical complexity of the sludge retrieval process, coupled with the challenging physical and radiological characteristics of the waste, necessitated a methodical and deliberate approach using unique design and operational solutions to safely conduct the work. This challenge was further complicated by the need to plan and conduct the work in two separate facilities, each subject to the controls and requirements of its own nuclear facility safety basis. The project overcame these challenges through creating an integrated team that actively engaged, communicated and coordinated each phase of the project to ensure successful completion. This paper will cover how these key elements of the Sludge Removal Project led to its success: - Integrating project planning and management; - Lessons learned from design and construction; - Preparing for a successful campaign (lessons learned from testing and start-up); - Lessons learned from operating in two separate facilities, transporting sludge containers on the Hanford Site and ensuring compliance with a range of regulatory and safety basis requirements. The establishment of an integrated group spanning two facilities and multiple organizations created a team capable of overcoming the challenges necessary to successfully plan and execute the sludge retrieval mission. Sharing lessons learned from this successful project can enhance the ability of teams across the DOE complex to successfully plan and execute complex projects. (authors)

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

Results of recent tests of GNS transport and storage casks for nuclear waste - 15285

State of the art dimensioning of casks for nuclear waste is changing rapidly in recent years. Therefore even established packages that serve the market for many years have to face new type testing programs that implements changes to its designs. The paper shows some of the recent testing programs for existing packages and provides an outlook to future casks solutions and its testing programs. (authors)

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

Utilizing Commercial Submersible Mixer Pumps for Sludge Removal in Savannah River Site's Tank 26 - 20289

The Savannah River Site (SRS) Liquid Waste System (LWS) safely manages, stores, treats, and dispositions liquid radioactive waste. The LWS consists of 51 underground waste storage tanks (eight of which are operationally closed and filled with grout), waste evaporators, treatment facilities, and solidification facilities, known as the Defense Waste Processing Facility (DWPF) and Saltstone Production Facility (SPF). One of the waste storage tanks, Tank 26, was placed into service in 1980 as an F Tank Farm (FTF) Evaporator Feed Tank. From 1980 to 2013, Tank 26 received F Canyon receipts and dilute supernate that was then transferred to the 242-16F FTF Evaporator for volume reduction. In 2013, the steam tube bundle failed in the FTF Evaporator, and the decision was made not to repair/resume evaporator operation. During operation of Tank 26, solids built up to a level of 2.03 m in the tank with a volume of 1062.9 kL. Due to the evaporator failure and subsequent shutdown, the solids in Tank 26 were selected to feed Sludge Batch 10, which is collected and prepped prior to being sent to DWPF for final disposition. To accomplish solids removal, Commercial Submersible Mixer Pumps (CSMPs) were selected to slurry the solids in preparation to be sent to Tank 51. Four CSMPs were installed in Tank 26 with each one installed in a separate quadrant of Tank 26. This work would mark the first deployment of CSMPs in an SRS waste tank. The CSMPs were developed in response to operational issues from previous mixing pumps and budgetary constraints. The CSMPs use the concept of modifying commercially available equipment for nuclear waste applications. The CSMPs consist of a 230-horsepower submersible mixing pump (manufactured by GPM, Inc.) joined to a mast fabricated at SRS. For this application, Savannah River Remediation (SRR) design services was challenged to provide a mast design that required no steel superstructure support system on top of Tank 26. Also, SRR design services provided a simplified Tank 26 riser interface that did not require extensive machine parts to adjust height of the suction screen of the CSMP within the tank. Other design improvements include no requirements for tank top radiation monitors and no requirements for flushing of the CSMPs during startup/shutdown operations. The CSMPs were operated at an initial height of 2.29 m above the Tank 26 bottom for 10 days. After sludge sounding, the CSMPs were lowered to a height of 1.52 m with no issues due to proper work planning and the simplified riser interface. With the CSMPs lowered to a level of 1.52 meters above the tank bottom, the CSMPs were operated for 12 days and another sounding was performed. The sounding level came back matching the disturbance depth results of the first pump run. Chemistry samples were analyzed while the tank was left to settle. The analysis revealed enough weight percent solids to provide good feed to Sludge Batch 10. Also, the results revealed the supernate within the mixture would provide good salt solution feed to Salt Waste Processing Facility (SWPF) Salt Batch 3. So, the plan was modified to let the disturbed solids settle and decant the salt solution for addition to SWPF Salt Batch 3. Then water will be added back to Tank 26, and the CSMPs run in order to wash the solids to decrease settling time prior to being sent to Tank 51 for Sludge Batch 10. Utilizing CSMPs for waste removal in an SRS Tank has provided a cost-effective means for further waste removal efforts. In addition, the CSMPs are easier to operate by utilizing a robust and simplified design. The CSMPs performed quite well with no process shutdown or delays during operation. As a result, CSMPs are integral to the future of removing radioactive waste from storage tanks at SRS. (authors)

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

When Every Drum is a Win - Tackling a Thirty-Five Thousand Drum Legacy - 20064

Cameco Corporation's (Cameco) Port Hope Conversion Facility (PHCF) was previously owned by the federal Crown Corporation, Eldorado Nuclear, which held a significant inventory of legacy waste material at the time Cameco was formed in 1988. As a result, Cameco was granted an allocation of 150,000 cubic metres of space in the Long-Term Waste Management Facility (LTWMF) located in the Municipality of Port Hope (MPH), which opened to the receipt of Cameco material in June 2018. Cameco is currently undertaking a major site cleanup and renewal of its Port Hope Conversion Facility (PHCF) which is known as the Vision in Motion (VIM) project. Over its operating history, Eldorado accumulated an inventory of over 35,000 drums of accumulated waste that was primarily stored at two offside warehouse locations. In 2017 and 2018, the project focused on repackaging two well characterized legacy wastes (magnesium fluoride slag and depleted uranium titanium oxide) from one of the two offsite locations. At the conclusion of this work, approximately 15,000 drums of these wastes had been repackaged and disposed of at the LTWMF. There remained approximately 1000 drums from this location that either could not be repackaged safely or were different waste types and required further verification and/or processing. The buildings at this location were scheduled for demolition in early 2019, which triggered the development of a process for triaging legacy drums in August 2018, which allowed for preparation and shipment of approximately half of these drums to the LTWMF by March 2019, with the remainder moved to the second offsite warehouse location in February 2019 for further characterization which is ongoing. This paper will discuss key lessons learned as the drummed legacy waste disposal inventory has been reduced to approximately half of the initial inventory. This will include the development of an alternate packaging process; prioritization of characterization activities and selection of techniques where minimal inventory information is available; determination of next step(s) for each drum as it is assessed; key safety considerations; and how to make inroads into an overwhelming task while under public and regulatory scrutiny. In a relatively short period of time, significant progress has been made to organize and gather information about the legacy waste, update the inventory records and determine the most appropriate pathways (i.e. LTWMF disposal, disposal at another appropriate facility, site storage until future processing and/or disposal). Since 2017 the volume of the decades-old legacy waste inventory has decreased significantly. With the majority of the known materials safely disposed of at the LTWMF, every drum removed from the endless rows of 20,000 pyramidally-stacked waste drums with limited history that is safely characterized, prepared and shipped is considered a win. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗