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At least 973 records · Page 54

Adsorptive Removal of Cs-137 and Sr-90 from Water in the Spent Fuel Pool of Taiwan Research Reactor - 18169

The cleanup of spent fuel pool in Taiwan Research Reactor (TRR) is a significant milestone in the decommissioning project of TRR. Due to the water was polluted by the ruptured spent nuclear fuel rods, the fission products and actinides were required to be removed from the water prior to transporting the water to the radioactive liquid wastes treatment plant. A granular aluminosilicate adsorbent (namely GWC) was loaded into a special designed water submersion adsorber to remove radionuclides from water in consideration of the subsequent retrieving after used. The unit is able to be placed underwater without heavy shield shroud, and easily to be assembled and disassembled. More than 95% of β-emitters had been removed from the 980 m{sup 3} of contaminated water in the SFP and generated about 1.5 m{sup 3} of spent GWC which adsorbed with 4*10{sup 12} Bq of radionuclides. (authors)

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Uncrewed Lunar Surface Operations and Support Activities

Sustained human presence on the surface of the Moon and future missions to Mars require increased independence from surface crews and Earth-based mission control to operate efficiently, safely, and reliably. The time for surface crews to perform tasks will be limited. Extravehicular activities by surface personnel are burdensome and time-consuming, even when a continuous human presence on the surface occurs. Identifying and balancing human/automation roles and tasks and infusing automation and autonomy practices early in a system’s lifecycle will be essential to achieve mission objectives. Among these objectives are attaining a sustained human presence, improving performance and mission effectiveness, reducing operations and maintenance (O&M) costs, and ensuring operations that are robust to communication delays. To achieve these objectives, an operational shift toward increased automation and autonomy with less reliance on humans is needed. Uncrewed lunar surface operations and support activities occur when surface crews are not present or are independent of surface crew timeline activities requiring no surface crew oversight or intervention. These uncrewed surface opportunities can also be planned to minimize crew workload that avoids routine maintenance and support tasks, thus maximizing crew exploration time. Uncrewed preparations such as staging and prepositioning equipment and materials before the crew arrives could improve crew task efficiency. Additional opportunities exist to conduct uncrewed science, exploration, and utilization. Uncrewed surface architecture functions can include science and exploration; habitation; launch and landing support; surface communication and navigation; surface power generation and distribution; human surface mobility; lifting, handling, manipulating; excavation, construction, and site preparation; logistics management; maintenance and repair; surface resource utilization; integrated site operations and shared support services (e.g., site scheduling/prioritization, dust mitigation/contamination control, and surface safety). Early robotic lunar surface campaigns will provide information on the availability of resources, such as oxygen and water, and demonstrate surface-based technologies. After the Artemis III human lunar return mission, a series of landers will deliver surface systems, cargo, supplies, science packages, spare parts, and commodities. A balance of crewed and uncrewed surface operations will enable a sustained lunar surface presence at the South Pole of the Moon at a site that will be known as the Artemis Base Camp (ABC). It is envisioned that base camp operations on and around the Moon will then help prepare for the mission durations and activities needed to support the first human mission to Mars. Before long-duration crew missions to the base camp can occur, the necessary surface infrastructure will be pre-deployed and verified operational. Surface assets will be teleoperated and remotely managed from Earth. Additionally, robotic and short-duration crewed missions to the ABC will ensure the site’s merit to achieve long-term science objectives, availability of usable resources, and that terrain, seasonal variations, and illumination conditions are acceptable. ABC will consist of different areas where specific functions and services are rendered, including: • Launch and Landing Area • Habitation Area • Power Production Area • Resource Areas Launch and Landing Area—The launch and landing area will support associated functions for the arrival and departure of vehicles, such as crewed landing and ascent and uncrewed cargo deliveries and offloading. It will evolve from an unimproved site at the beginning of the exploration campaign to a more sustainable landing and launch area that can support repeated arrivals and departures. Initial uncrewed Lunar Terrain Vehicle (LTV) surface operations may include emplacement of navigation beacons and communication equipment, real-time video and photography of landing/liftoff events, and element repositioning, such as portable utility power (PUP) (applicable for other landed assets at other areas). Site preparations, such as surface leveling, soil compaction, and berm/path construction, may be needed for a more sustainable launch and landing area capable of accommodating vehicles that are increasingly more reusable and reduce the effects of plume surface interactions and ejecta impacts on nearby surface assets. During the ABC missions, cargo and logistics will be delivered to the lunar surface via robotic cargo landers before the crew arrives. These shipments, which can arrive in pressurized logistics carriers, will deliver the logistics necessary to support a crewed mission and include items such as food, water, equipment spares, etc. Providing the capability to retrieve, offload, and transport the logistics closer to the ABC site before the arrival of the crew will increase the overall efficiency of crew operations once they arrive. In the sustained phase of exploration, other supporting services may be needed, such as lander propellant servicing, surface power services, commodity refreshes, and additional inspection, maintenance, and repair capabilities, to sustain a cadence of extended personnel stays and cargo arrivals and departures. Habitation Area—Uncrewed support to surface habitation could involve supporting activation and pre-entry operations of the habitat while the crew is in orbit at the Gateway outpost preparing for a surface landing. Surface Habitat (SH) uncrewed operations may include bringing the cabin environment to a habitable temperature and air mix and activating other critical crew support systems. Potential crop production uncrewed tasks in the SH could also include autonomous watering and tending. Additionally, when the crew departs, the SH enters dormancy for the long period of uncrewed operation. A logistical staging area could also be collocated near the SH. If so, staging operations for crew supplies, waste re-location, and recycling operations may be opportunities for uncrewed operations. Power Production Area—The Fission Surface Power (FSP) element and its supporting distribution equipment provide power to surface elements as needed across the ABC to supplement day-to-day operations and survive lunar nights. Uncrewed support of this power system includes any initial LTV-assisted deployments of cables and other distributed equipment, associated electrical connections, and system testing and activation operations. Robotically performing some inspections, maintenance, or repair tasks on the power distribution equipment could reduce the surface crew workload. Resource Area— Uncrewed resource prospecting, mapping, and characterizing possible resource sites is likely to be time-consuming and represents an opportunity for uncrewed operations between crewed missions. Uncrewed mobile equipment operations will be needed in the extreme environments of permanently shadowed locations where resource extractions occur. As In-Situ Resource Utilization (ISRU) pilot plant operations begin, uncrewed surface support activities with available mobile and portable assets (LTV, PUP, etc.) will better support these operations. Any produced commodities can be stored at a centralized storage location for future use. Also associated with these operations is the use of mobile robotic excavators for resource acquisition and robotic/autonomous regolith processing. The waste tailings generated during excavation and regolith processing would also need to be transported and deposited at a dedicated location. Surface assets will continue operating between crew visits to maintain surface capabilities, conduct lunar surface science, technology demonstrations, and public outreach opportunities. Additionally, certain sustaining tasks that would consume valuable crew time could be performed before crew arrival, or after their departure. This capability may offer more affordable options to construct, activate, test, and maintain a broad set of surface assets. Telerobotically operated human surface mobility systems, such as the LTV and Pressurized Rover (PR), can be utilized for various tasks. Surface environmental conditions pose a distinct challenge for all these activities. Surface illumination and localized shadows are one such factor. Night-survival operations could consist of thermal management, battery pre-charging, and load shedding. Some surface systems may hibernate through the night and then awake and continue nominal operations. Uncrewed mobile assets may use a more adaptive approach to optimize their power and operations; one method is to follow the sunlight. Night-survival operations may be initiated remotely by teleoperation, automated, or accomplished by supervised autonomous operation. The ability to pre-deploy and control remote assets in orbit or on Mars before the arrival of the mission crew is a key capability that can be simulated on the moon. The base camp provides a venue where these advanced operational concepts, technologies, and autonomous methods and techniques, including the incorporation of time delays to simulate Earth-Mars latency can be replicated to help buy down future Mars mission risks. This paper will examine the evolution of uncrewed lunar surface operations and support activities. It will also discuss the lunar surface environmental conditions (thermal, lighting, terrain, topography, communications) along with the challenges they pose on uncrewed surface operations, and the performance of these activities with limited to minimal human interaction and/or teleoperation. Since lunar missions include Mars mission analogs, such investigation provides the framework for future uncrewed Mars mission support.

Mark E Lewis↗

Support for DF LAW Flowsheet Development Report [Final Report]

The primary objectives of this work were to develop a glass formulation for the direct feed LAW from Tank AP-105, collect data on primary off-gas system effluents to support the evaluation of potential direct feed LAW flowsheets, and determine the effect of the dilute direct feed LAW stream on processing rates and partitioning of waste components to the exhaust system. Development of a suitable glass formulation for the LAW Tank AP-105 composition made use of information from the ORP Enhanced LAW Glass Correlation that is currently under development. Subsequently, melter feeds at low solids contents indicative of direct feed LAW waste streams were processed on the DM100 to determine glass production rates and bubbling rates required to process the high water content feed. Liquid effluent solutions generated from prototypical primary off-gas system components (SBS and WESP) were collected while processing the LAW Tank AP-105 composition at nominal conditions through the DM10. These solutions were analyzed to determine their steady state compositions and the effects of feed composition and feed water content at nominal processing conditions.

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Solidification of REDC Organics and Airborne Release Fraction Measurements

The Radiochemical Engineering Development Center (REDC) generates various liquid organic wastes from processing irradiated targets to recover heavy elements. In the past, these organics were discharged to the Oak Ridge National Laboratory (ORNL) liquid low-level waste (LLLW) system, along with the aqueous waste. Because of a reduction in aqueous LLLW from other ORNL generators and an increase in the radionuclide concentration, particularly 238 Pu, in the organic waste stream, the organics can no longer be discharged to the LLLW system. The plan is to solidify the liquid organic waste for disposal as solid debris waste. The documented safety analysis for REDC uses an airborne release fraction of 5 x 10 -4 with a respirable fraction of 0.2 for plutonium and other actinides from packaged solid debris waste during a fire scenario, for an overall airborne release fraction/respirable fraction of 10 -4 . Solidifying the organic liquids, either by using PM-199 Organoclay ® or by grouting, would produce solid waste forms with no free liquid, which should qualify for disposal at the Waste Isolation Pilot Plant. The use of Organoclay would be much simpler to implement inside a hot cell. Granular Organoclay can be added to the organic waste solutions until there is a dry layer on top of the liquid and then allowed to cure for a few hours. Grouting the liquids would require using multiple ingredients and mixing steps. Both methods produced waste forms that trapped cerium, as a surrogate for plutonium, inside the waste, with airborne release fractions during fire scenario tests of well below the 10 -4 limit.

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Solidification of REDC Organics For Disposal As Solid Waste

The Radiochemical Engineering Development Center (REDC) generates various liquid organic wastes from processing irradiated targets to recover heavy elements. In the past, these organics were discharged to the Oak Ridge National Laboratory (ORNL) liquid low-level waste (LLLW) system, along with the aqueous waste. Because of a reduction in aqueous LLLW from other ORNL generators and an increase in the radionuclide concentration, particularly 238 Pu, in the REDC organic waste stream, the organics can no longer be discharged to the LLLW system. The plan is to solidify the liquid organic waste for disposal as solid waste. Solidifying the organic liquids using PM-199 Organoclay ® would produce solid waste forms with no free liquid, which should qualify for disposal at the Waste Isolation Pilot Plant. Granular Organoclay can be added to the organic waste solutions until there is a dry layer on top of the liquid and then allowed to cure for a few hours to produce a solid wasteform.

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Deployment of large tank monosodium titanate strike to increase salt processing at the Savannah river site - 15115

The treatment of high level waste (HLW) salt solutions using the Actinide Removal Process (ARP) and Modular Caustic Side Solvent Extraction Unit (MCU) began at Savannah River Site (SRS) in 2008. Since that time, over 6 million gallons of liquid HLW have been treated and the resulting low level waste (LLW) effluent immobilized in cementitious grout at salt-stone. In addition to the continued stabilization of liquid HLW, operating experience from the ARP/MCU facilities has also been valuable in considering the design and construction of the Salt Waste Processing Facility (SWPF) which will utilize similar unit operations on a much larger scale. ARP removes actinides by contacting waste with monosodium titanate (MST) which is a solid adsorbent for soluble strontium and actinides. Once the sorption reaction is complete, the MST solids are separated from salt solution via ultrafiltration through a crossflow filter. The throughput of initial operations of ARP/MCU was limited by the flowrate through the extraction process. However, after the implementation of a new solvent flowsheet, filtration of MST will be the rate limiting step in salt processing. For the entirety of ARP/MCU operation, Savannah River Remediation (SRR) has sought to improve process efficiency and performance through optimization and modification of the original facility design. These efforts have resulted in a best-single-year throughput of 4.9 million liters of decontaminated salt solution. In keeping with these practices, SRR recently initiated a project to improve filtration throughput by relocating the MST strike from small batches immediately upstream of the filtration unit to the underground waste tank used to batch and store salt solution feed for ARP/MCU. This process change will allow the bulk of MST solids to decant in the waste tank prior to filtration which should improve both the nominal operational filter flux as well as the achieved utility of filter operation. (authors)

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Proposed Analytical Methods for Determining Filter Media Properties

High Efficiency Particulate Air (HEPA) filters, commonly used in nuclear filtration applications, are an integral part of the waste management processes in nuclear plants. HEPA filters are 99.97% efficient filtration devices characterized by their high resistance to air flow, or pressure drop. From theoretical models, the initial pressure drop across a clean filter is proven to be a function of the filter media fiber diameters and porosity of the media. These filter properties are relatively difficult to obtain with traditional manual methods; therefore, there is a need to develop analytical methods to find the fiber diameter and porosity to determine the pressure drop. Typically, these values can be found by substituting a calculated representative value based upon measured values, such as equivalent fiber diameter based upon a clean pressure drop. However, these values may also be directly recorded and measured by incorporating Scanning Electron Microscope (SEM) image analysis and other measurement methods to analyze the filter media and determine its physical properties without the need for media testing. DiameterJ, an open source Java plug-in, used with ImageJ, can process images of filter media taken by an SEM to find statistical data such as mean fiber diameter and porosity. To produce the raw data, SEM images of two filter media type samples are taken and segmented in DiameterJ using the traditional and statistical region merging segmentation algorithms. Manual segmentation is necessary after the initial segmentation by the algorithms as the images tend to be too complex for the algorithms to output with the necessary accuracy. However, complications exist in the manual segmentation process as these methods can be time intensive and prone to the individual bias of the user. This in turn can skew the final mean fiber diameter result, and lead to either an over or under prediction of the pressure drop. It was also discovered that the porosity data produced by DiameterJ is inaccurate, as the SEM analyzes the three-dimensional filter media by projecting its geometry onto a plane and analyzing it as a two-dimensional binary image. Thus, the porosity is artificially inflated through the segmentation process, rendering this result incorrect. Alternatively, density determination, gravimetric analysis, and thickness testing of the filter media is collectively used to determine the filter fiber porosity. Together, the SEM image analysis and analytical lab methods produce results through direct measurements which allow for the prediction of the initial pressure drop from clean filter media without the need for prior media testing to collect pressure data. By improving upon this proposed analytical method in the future, there is potential to streamline the process of finding these filter properties into a more direct methodology for determining the pressure drop across HEPA filters.

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Carbon dioxide evolution rate as a method to monitor and control an aerobic biological waste treatment system

An experimental system was developed to study the microbial growth kinetic of an undefined mixed culture in an erobic biological waste treatment process. The experimental results were used to develop a mathematical model that can predict the performance of a bioreactor. The bioreactor will be used to regeneratively treat waste material which is expected to be generated during a long term manned space mission. Since the presence of insoluble particles in the chemically undefined complex media made estimating biomass very difficult in the real system, a clean system was devised to study the microbial growth from the soluble substrate.

Lee, S. S.↗

Leaning the tank closure process at the Savannah River Site - 15515

The Savannah River Site liquid waste system consists of multiple facilities that safely receive and store legacy radioactive waste prior to treatment and disposition. The liquid radioactive waste is stored in large underground tanks. The waste inventory currently stored in these tanks is a complex mixture of insoluble metal hydroxide solids and soluble salt supernate. The high-level (radioactive) portion of the waste is vitrified into a glass waste form, while the low-level waste is immobilized into a cementitious grout waste form called salt-stone. Once the waste is retrieved and processed, the tanks are closed. The closure process includes; waste removal, characterizing residuals, isolating the tank systems, and stabilizing the tank with tailored grout formulations. The core of Lean is to eliminate waste or non-value added steps from processes to maximize customer value. From the perspective of the customer, 'value' is defined as any action or process for which a customer would willingly pay. In this case our product is to safely and efficiently remove waste from the underground storage tanks and demonstrate operational closure to the State of South Carolina. Savannah River Remediation (SRR) initiated the use of the Lean process in late 2013 and identified the Tank Closure process as one of the targeted areas to improve. The first step in the Lean process is to 'map' out the value stream and identify areas where non-value added steps are present and then prioritize Rapid Improvement Events (RIE). Based on this mapping process, there were a number of areas that SRR determined warranted further evaluation for improvements, including; standard equipment design, characterization, standard work packages, regulatory documentation, tank characterization, structural evaluations, engineering documentation and equipment re-use. This paper focuses on the application of the Lean process at SRR and more specifically, effective application to the Tank Closure Process. This paper discusses the value stream mapping process for Tank Closures, as well as, summarizes the RIEs and demonstrate the realized benefits. Benefits can come in a variety of forms, from schedule compression to decreased costs. Through the Lean process we have been able to identify close to $10 M in savings over the life cycle of the tank closure process and a 4 year schedule compression. Cost and schedule savings are used to accomplish further risk reduction efforts. In addition to hard benefits, there are also soft benefits. These soft benefits are a result of the process itself and help drive improved efficiencies through better communication with key stakeholders, such as regulators and customers. (authors)

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Sustainable Security through International Source Repatriation - 19659

Ensuring that there is a viable pathway for characterizing, transporting, and disposing of disused radioactive sealed sources (sources) is essential to any end-of-life management strategy. The Off-Site Source Recovery Program, sponsored by the Department of Energy National Nuclear Security Administration's Office of Radiological Security, provides permanent and sustained threat reduction through the secure removal and repatriation of disused sealed radioactive sources of United States origin at international locations. With over two decades of operations, the Off-Site Source Recovery Program has developed source removal processes and techniques to ensure the compliant, effective and timely disposition of the material. For device disassembly support, the program subcontracts vendors qualified and experienced in source extraction from devices. United States origin source repatriations provide for permanent threat reduction and reduce their overall global footprint. (author)

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Seismic design of a nuclear waste repository against an earthquake induced rock shear load - 15346

Concepts for isolation of spent nuclear fuel have been studied by organizations in countries that employ nuclear power. These concepts typically involve a deep geological repository in bedrock, with processed radioactive waste encased in deposition canisters emplaced in underground excavations and surrounded by clay-based buffer. This multi-barrier approach is intended to provide long-term isolation of the waste package from the biosphere. According to many statistics, there is a tendency toward increasing numbers of earthquakes in the Korean peninsula each year. If an earthquake induced rock shear load occurs at a repository site, the engineered barrier system (EBS) can be sheared, resulting in a pressure increased in the buffer material. This is expected to result in damage to the canisters. Therefore, because the damage, which can be fatal to a disposal canister, can be given in case an earthquake occurs, the method protecting the canisters safely is needed. In this paper, 'an earthquake-resistance type buffer' was proposed using a method for protection from earthquake damage. To aid in achieving this objective, we have developed a technique for estimating the behavior of the EBS affected by earthquake induced rock shear using an analysis method, such as finite element method. As a first step, experimental tests are performed for understanding the behavior of the buffer material. Comparing the results of the numerical simulations to the experimental results can be used to verity the reliability of the analysis model. Then we developed the real scale analysis model of a nuclear waste repository. The main parameter having an effect on the earthquake-resistant performance was analyzed and an earthquake-resistance proof type buffer was designed. To improve the earthquake-resistance performance, we designed the buffer by putting the low- density buffer between the canister and buffer. The simulation results show that the earthquake-resistant performance was improved by about 65%. (authors)

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Characterization of Tc-99 Speciation and Chemical Composition of 241-AN-102 Tank Waste Supernatant - 19201

Technetium (Tc) in its isotopic form {sup 99}Tc is generated in high yields from the fission of {sup 235}U and {sup 239}Pu. A significant inventory of {sup 99}Tc remains at the U.S. Department of Energy's Hanford Site, and it is one of the most difficult contaminants to address. In the strongly alkaline solutions that are typical of Hanford tank waste, Tc exists as both pertechnetate (TcO{sub 4}{sup -} in oxidation state VII) and in reduced forms (oxidation state <VII) collectively known as non-pertechnetate species. Pertechnetate is a well-characterized anionic Tc species that can be removed from low-activity waste by anion exchange or other methods. There is no definitive information on the origin or a comprehensive description of the non-pertechnetate species in Hanford tanks. Designing strategies for effective management of Tc, including separation and immobilization, requires an understanding of the molecular structure of the non-pertechnetate species and their identification in actual tank waste samples. Developing this advanced understanding would facilitate development of new technologies for treating dissimilar Tc species. Toward this objective, a spectroscopic library of the Tc(I) [fac-Tc(CO){sub 3}]{sup +} and Tc(IV, VI, VII) compounds was generated using a range of techniques and applied to the characterization of actual 241-AN-102 tank waste supernatant. A sample of the 241-AN-102 tank waste (collected in 2013) was processed to remove {sup 137}Cs by spherical resorcinol-formaldehyde (sRF) ion exchange resin after the sodium concentration was adjusted to 5.6 M. The Cs-loaded sRF column was eluted with 0.45 M HNO{sub 3}. As-received AN-102, Cs-depleted AN-102 effluent, and sRF eluate fractions were comprehensively characterized for chemical composition and speciation of Tc using {sup 99}Tc nuclear magnetic resonance (NMR) spectroscopy and X-ray absorption spectroscopy. The results of these analyses demonstrated for the first time that non-pertechnetate Tc present in the 241-AN-102 tank waste is composed of several low-valent Tc species, including the Tc(I) [fac-Tc(CO){sub 3}L{sub 3}]{sup +}, Tc(IV), and possibly Tc(VI) compounds. This is the second experimental observation of the [fac-Tc(CO){sub 3}L{sub 3}]{sup +} species in the Hanford tank waste that highlights their importance for waste processing. In addition, the chemical composition of the 241-AN-102 tank waste was characterized with the focus on small chelators. (authors)

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Nuclear Safety [Vol. 32, No. 1, January-March 1991]

Nuclear Safety is a review journal that covers significant developments in the field of nuclear safety. Its scope includes the analysis and control of hazards associated with nuclear energy, operations involving fissionable materials, and the products of nuclear fission and their effects on the environment. Primary emphasis is on safety in reactor design, construction, and operation; however, the safety aspects of the entire fuel cycle, including fuel fabrication, spent-fuel processing, nuclear waste disposal, handling of radioisotopes, and environmental effects of these operations, are also treated. Table of Contents for this issue follows. GENERAL SAFETY CONSIDERATIONS: 1 The Safety Review and Approval Process for Space Nuclear Power Sources, G. L. Bennett; 19 Report on the American Nuclear Society International Topical Meeting: "The Safety, Status, and Future of Non-Commercial Reactors and Irradiation Facilities", E. G. Silver; 35 Book Review: Fission Product Transport Processes in Reactor Accidents, Proceedings to the International Centre tor Heat and Mass Processes T. S. Kress; 38 Fast Reactor Technology in the 1990s: A Summary of the 1990 International Fast Reactor Safety Meeting, A. E. Levin; ACCIDENT ANALYSIS: 56 Effects of Chemical Phenomena on LWR Severe Accident Fission Product Behavior, A. P. Malinauskas and T. S. Kress; CONTROL AND INSTRUMENTATION: 65 Technical Note: Safety Parameter Display Systems—10 Years Later, R. J. Eckenrode; 68 Potential Application of Neural Networks to the Operation of Nuclear Power Plants, R. E. Uhrig; DESIGN FEATURES: 80 Twenty-First DOE/NRC Nuclear Air-Cleaning Conference, R. R. Bellamy, D. W. Moeller, and M. W. First; 91 Impact of an Apparent Radiation Embrittlement Rate on the Life Expectancy of PWR Vessel Supports, R. D. Cheverton, G. C. Robinson, W. E. Pennell, and R. K. Nanstad; ENVIRONMENTAL EFFECTS: 103 Technical Note: The Impact of Offsite Factors on the Safety Performance of Small Nuclear Power Plants, Yu. D. Baranaev and A. N. Viktorov; WASTE AND SPENT FUEL MANAGEMENT: 109 Activities Related to Waste Management, Compiled by E. G. Silver; OPERATING EXPERIENCES: 118 Reactor Shutdown Experience, Compiled by J. W. Cletcher; 121 Selected Safety-Related Events, Compiled by G. A. Murphy; 123 Operating U.S. Power Reactors, Compiled by E. G. Silver; RECENT DEVELOPMENTS: 140 General Administrative Activities, Compiled by E. G. Silver; 150 Reports, Standards, and Safety Guides, D. S. Queener; 155 Status of Power-Reactor Licensing Activities, Compiled by E. G. Silver; 157 Proposed Rule Changes as of Sept. 30, 1990; ANNOUNCEMENTS: 79 MIT Offers Summer Program on Nuclear Power Reactor Safety; 108 Harvard School of Public Health Offers Several Short Courses; 139 Short Course and Workshop on Nuclear Criticality Safety at University of New Mexico; 160 SCK/CEN Announces Training Course on Emergency Planning and Response; 161 The Authors; 164 Indexes to Nuclear Safety, Volume 31

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Characterization of the March 2017 Tank 15 Waste Removal Slurry Sample (Combination of Slurry Samples HTF-15-17-28 and HTF-15-17-29)

Two March 2017 Tank 15 slurry samples (HTF-15-17-28 and HTF-15-17-29) were collected during the second bulk waste removal campaign and submitted to SRNL for characterization. At SRNL, the two samples were combined and then characterized by a series of physical, elemental, radiological, and ionic analysis methods. Sludge settling as a function of time was also quantified. The characterization results reported in this document are consistent with expectations based upon waste type, process knowledge, comparisons between alternate analysis techniques, and comparisons with the characterization results obtained for the November 2016 Tank 15 slurry sample (the sample collected during the first bulk waste removal campaign).

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Optimization of the Post-Operational Phase on Two Belgian Multi-Unit Nuclear Power Plants: the Case of the Non-Fissile Irradiated Core Items - 20156

The current legal framework in Belgium foresees the progressive phase out of nuclear power between October 2022 (Doel 3) and December 2025 (Doel 2). Upon its definitive shutdown, each unit of the Tihange and Doel sites will enter a Post-Operational Phase (POP) and be prepared for its Decontamination and Decommissioning (D and D). Prior to obtaining the D and D license, the Operator Electrabel is legally required to remove any non-fissile irradiated core items stored in the deactivation pools. The non-fissile irradiated core items consist essentially of control rods, poison rods and source thimbles as well as thimble plugs and foreign materials irradiated during operation: - Their significant content in highly radiant radionuclides (up to 6 TBq of Co-60 per kg of irradiated material) renders all existing operational waste management processes inadequate due to insufficient biological shielding; - Their high concentrations in long-lived radionuclides call for their disposal in a geological repository for which no final design nor waste acceptance criteria are expected prior to 2050. Uncertainties in the Belgian energy supply and security, however, require the Operator to be prepared for a partial nuclear phase out, where one or more units would benefit from lifetime extension while the remaining units would undergo decommissioning. The present paper aims at presenting how Electrabel, in partnership with Tractebel, addressed this challenge by maximizing the use of synergies within the respective sites as well as between both sites themselves, all the while accounting for site specificities. The most recent results and state of progress of the project will be detailed and the first lessons learned will be shared. The project has been split in multiple tasks and phased as follows: - An inventory phase aimed at mapping the contents, origin, composition and history of the non-fissile irradiated core items; - A pre-characterization phase based on neutron activation models; - A waste sorting phase aimed at separating waste forms for which an evacuation route exists from those for which such route does not exist; - A feasibility phase aimed at exploring all possible scenarios for the management of non-fissile irradiated core items and identifying the optimal feasible solution for each site; - A preparation phase (currently ongoing), developing further the optimal solution and ensuring that back-up solutions are available for any foreseeable change of context (licensing issue, modification in the nuclear phase-out program, etc.) and initiating early contacts with potential subcontractors for segmentation works and cask manufacturers, as well as the Belgian regulatory body and waste management agency. This phase also foresees the investigation of destructive and non-destructive radiological measurements to support the detailed characterization of the waste forms; - A realization phase (future work). (authors)

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Management of Metals from Decommissioning of Nuclear Facilities - 18411

The EDF group companies within the Cyclife platform have for decades performed treatment and recycling of metals. With different approaches but all considered international Good Practice, as valuable materials are recovered for safe recycling and volumes in the repositories for radioactive waste are saved. For an efficient decommissioning project, a well-defined waste management process is one of the critical paths, not least when it comes to routes for clearance and recycling of materials. It is easy to underestimate the complexity and bottlenecks caused by shortage of logistic space. In order to mitigate these risks, activities such as strengthening categorization, quantification and adopting different routes based on the material properties should be implemented. By categorization of the of waste and materials considered/classified as contaminated or potentially contaminated it is obvious that the management of the metals is a key parameter in nuclear decommissioning. Analyses performed by the EDF companies shows that a majority of the materials, classified as contaminated, from a BWR/PWR plant are metals. Experience gives that a high percentage of these metals from decommissioning can be subject to recycling either directly upon completion of the clearance process or after certain treatment. Non-technical key parameters like the regulatory requirements on applying the waste hierarchy, the impact on repository programs as well as, not at least, the regulatory and public acceptance of recycling of materials from the nuclear industry are, together with costs essential factors when forming the routing of metals and other waste materials from a decommissioning project. Today the EDF group companies are positioned to provide a wide range of services for management of the contaminated metals from decommissioning projects, spanning from industrial management of metals which directly will be subject general clearance after verification measurements up to decontamination and melting of selected reactor internals for recycling to public domain or within the nuclear industry. In this paper the typical waste material composition for BWR and PWR plants, the different ways to treat/manage the radioactive and potentially radioactive metals including a comparison of the different approach commonly used in a technical, logistical and economical perspectives. A few success stories will be resented as well as lessons learned. (authors)

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'A Good Decision Is Based On Information, Not On Numbers' - A Process For National Strategic Decision Making - 17203

Waste management decision making is the process used by waste owners to determine and justify choices in across the lifecycle of a waste (from the manner of generation or retrieval to final disposition). In the UK, waste owners in the nuclear industry are obligated, by their environmental permits and authorisations, to demonstrate the application of robust and well-underpinned decision making processes for waste management. This is captured through the requirement for waste owners to demonstrate the identification and implementation of Best Available Technique (BAT). The National Waste Programme (NWP), led by LLW Repository Ltd, is a UK wide programme which leads the implementation of the UK National Strategy for the management of solid LLW from the nuclear industry [1] and which aims to deliver a self-sustaining culture for optimised management of Low Level Waste (LLW) in the UK. Recognising the requirement on waste owners, the NWP has - in conjunction with appointed contractors - led the development and publication of national strategic optioneering studies (so-called national strategic BAT studies) to support waste owners. Recognising the benefits that this approach to optioneering and strategic decision making could have for other waste producers, this paper provides an overview of the process used for the development of the suite of national strategic BAT assessments for the NWP. It details: the main phases of the process, the key features of each process phase, the benefits of the approach and key learning from its deployment in practice. Note: The legislative regime in England and Wales requires the identification and application of BAT. There is an equivalent regime in Scotland known as Best Practicable Environmental Option (BPEO) and Best Practicable Means (BPM). The requirements are comparable across the two legislative regimes and, for the purposes of simplicity, the term BAT will be utilised in this paper. The approach and outcomes of the national strategic optioneering process described are applicable across the UK. (authors)

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Experimental Evaluation of Dual-Opposed Jet Mixer Pump Performance for Slurry Mixing

Million-gallon double-shell tanks at Hanford are used to store transuranic, high-level, and low-level radioactive wastes. These wastes consist of a large volume of salt-laden solution covering a smaller volume of settled sludge primarily containing metal hydroxides. These wastes will be retrieved and processed into immobile waste forms suitable for permanent disposal. Retrieval is an important step in implementing these disposal scenarios. The retrieval concept evaluated is to use submerged dual-nozzle jet mixer pumps with horizontally oriented nozzles located near the tank floor that produce horizontal jets of fluid to mobilize the settled solids. The mixer pumps are oscillated through 180 about a vertical axis so the high velocity fluid jets sweep across the floor of the tank. After the solids are mobilized, the pumps will continue to operate at a reduced flow rate producing lower velocity jets sufficient to maintain the particles in a uniform suspension (concentration uniformity). Several types of waste and tank configurations exist at Hanford. The jet mixer pump systems and operating conditions required to mobilize sludge and maintain slurry uniformity will be a function of the waste type and tank configuration. The focus of this work was to conduct a 1/12-scale experiment to develop an analytical model to relate slurry uniformity to tank and mixer pump configurations, operating conditions, and sludge properties. This experimental study evaluated concentration uniformity in a 1/12-scale experiment varying the Reynolds number (Re), Froude number (Fr), and gravitational settling parameter (Gs) space. Simulant physical properties were chosen to obtain the required Re and Gs where Re and Gs were varied by adjusting the kinematic viscosity and mean particle diameter, respectively. Test conditions were achieved by scaling the jet nozzle exit velocity in a 75-in. diameter tank using a mock-up of a centrally located dual-opposed jet mixer pump located just above the tank floor. Concentration measurements at sampling locations throughout the tank were used to assess the degree of uniformity achieved during each test. Concentration data was obtained using a real time in-situ ultrasonic attenuation probe and post-test analysis of discrete batch samples. The undissolved solids concentration at these locations was analyzed to determine whether the tank contents were uniform (≤ ±10% variation about mean) or nonuniform (> ±10% variation about mean) in concentration. Concentration inhomogeneity was modeled as a function of dimensionless parameters. The parameters that best describe the maximum solids volume fraction that can be suspended were found to be 1) the Fr based on nozzle average discharge velocity and tank contents level and 2) the dimensionless particle size based on nozzle diameter. The dependence on the jet Re does not appear to be statistically significant.

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