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At least 1,729 records · Page 96

High Temperature Ternary Chloride Molten Salt Pump

This work investigates the design criteria considering thermal, structural, and mate-rial selection of a ternary chloride (MgCl2-NaCl-KCl) molten salt pump that is capable of running at temperatures above 720 °C. In this work, preliminary testing of salt-wetted hydrodynamic bearings was done to investigate different material pairings including colmonoy grades, stellite grades, and a novel NiWC-based alloy (i.e. HybrimetTM NiWC3b) used as a High Velocity Ox-ygen Fuel (HVOF) coating. The coating has shown to withstand the corrosive nature of the salt, and is additionally used to protect a 316L stainless steel pump reservoir. The pump wetted components are made of Inconel 625, and it features a carbon ring seal developed by Flows-erve flooded with a N2 gas flow on the overhead to keep salt vapors from interacting with the external ambient air. This research showcases a promising design for use in the CSP Gen 3 liquid-pathway and sets the ground for further development and use of the HybrimetTM NiWC3b as a competitive alternative to available superalloys. Further work will further characterize the pump by performance & cycle testing in molten salt at higher temperatures.

14 SOLAR ENERGY↗

Arvia organics destruction: an innovative treatment approach for dioxins, furans and other problematic (Orphan) organic wastes - 15380

The safe and efficient disposal of radionuclide-contaminated organic wastes is a key component in the life-cycle of a nuclear power plant. Technologies are available for the processing of some of these wastes although there are a number of waste streams for which the disposition path is not clear or does not exist at all. For example, waste streams such as dioxin, furan and PCB-laden oils pose an issue for the US Dept. of Energy complex. These wastes present a challenge as they cannot be readily treated using existing treatment technologies because of legislative and material constraints such as gaseous phase radioactivity discharge limits, waste elemental content, by-product generation and waste resistance to thermal decomposition. Alternate methods of organics destruction can circumvent some of these issues by using different mechanisms of organics oxidation. One such innovative method, known as the Arvia organics destruction process, combines adsorption with electrochemical combustion and offers such an alternative. This technology, based on a patented material, Nyex{sup TM} that is able to act as both an adsorbent and as an electrode, allows the electrochemical combustion of adsorbed organics to occur on the material's surface. The result is the destruction of organics whilst the bulk of inorganic and radionuclide components remain in the aqueous phase. These components can subsequently be treated using existing waste processing technologies. This paper outlines recent work conducted on demonstrating the Arvia process against the destruction of dioxin, furan and PCB-laden wastes that demonstrates that the technology successfully removes these target species to below discharge standards in the aqueous phase. Based on these successful trials a test unit has been designed to demonstrate the process on actual radioactive wastes at the DOE Oak Ridge facility. The successful treatment of F027-coded waste has also been demonstrated and will be reported. The above work showcases the development, scaling and application of an innovative technology, first presented to the industry at the Waste Management Symposia in 2012, as another option for the treatment of challenging wastes with expensive, complex or no current disposal routes. The Arvia process adds to the portfolio of available treatment technologies and will help facilitate the decommissioning and waste disposal responsibilities of the nuclear industry. (authors)

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Arvia Organics Destruction: An Innovative Treatment Approach for Dioxins, Furans and Other Problematic (Orphan) Organic Wastes - 16262

The safe and efficient disposal of radionuclide-contaminated organic wastes is a key component in the lifecycle of a nuclear power plant. Technologies are available for the processing of some of these wastes although there are a number of waste streams for which the disposition path is not clear or does not exist at all. For example, waste streams such as dioxin, furan and PCB-laden oils and aqueous organic matrices pose an issue for the US Dept. of Energy complex. These wastes present a challenge as they cannot be readily treated using existing treatment technologies because of legislative and material constraints such as gaseous phase radioactivity discharge limits, waste elemental content, by-product generation and waste resistance to thermal decomposition. Alternate methods of organics destruction can circumvent some of these issues by using different mechanisms of organics oxidation. One such innovative method, known as the Arvia organics destruction process, combines adsorption with electrochemical combustion and offers such an alternative. This technology, based on a patented material, Nyex{sup TM} that is able to act as both an adsorbent and as an electrode, allows the electrochemical combustion of adsorbed organics to occur on the material's surface. The result is the destruction of organics whilst the bulk of inorganic and radionuclide components remain in the aqueous phase. These components can subsequently be treated using existing waste processing technologies. This paper outlines recent work conducted on demonstrating the Arvia process against the destruction of dioxin, furan and PCB-laden wastes that demonstrates that the technology successfully removes these target species to below discharge standards in the aqueous phase. Based on these successful trials a test unit has been designed to demonstrate the process on actual radioactive wastes at the DOE Oak Ridge facility. During commissioning at Arvia's facility the unit achieved a destruction rate of over 1.5 ml of 100% organic waste per hour. The unit is currently at a partner laboratory facility based at Oak Ridge National Laboratories and has recently completed a further suite of simulant trials which are reported here. The above work showcases the development, testing and initial application of an innovative technology, first presented to the industry at the Waste Management 2012, as another option for the treatment of challenging wastes with expensive, complex or no current disposal routes. Over the years the technology has gone through a number of proving stages culminating in the testing on real orphan wastes based at the Oak Ridge Facility. The Arvia Organics Destruction Cell technology adds to the portfolio of available treatment technologies and will help facilitate the decommissioning and waste disposal responsibilities of the nuclear industry. (authors)

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Greater Efficiency in the Management of Low-Level Radioactive Material - 18305

The World Nuclear Association is the international organization representing the global nuclear industry. Its mission is to promote a wider understanding of nuclear energy among key international influencers by producing authoritative information, developing common industry positions, and contributing to the energy debate. Membership encompasses companies from the whole fuel cycle (from uranium mining through to decommissioning) as well as support services. Through discussions and survey of the Association's Waste Management and Decommissioning Working Group, it is clear that there is an issue relating to the management of cleared and/or low level radioactive material, particularly during decommissioning where it represents more than 90% of all wastes generated. The group has found that the status quo on the reuse, recycling and disposal of cleared and/or low-level radioactive material arising from the civil nuclear industry (all successfully tested and implemented options) is untenable, and believes that this message should be conveyed to relevant influencers internationally. This message is key and features prominently in a methodological guide being prepared by the group's experts on managing waste from decommissioning which will work through case studies (relating to both technical and financial management) and showcase good practice to support the development of a successful decommissioning strategy. There are currently nearly 450 operating civil nuclear power reactors in the world with many associated nuclear fuel cycle and nuclear research facilities. During the operation and subsequent decommissioning of nuclear facilities, cleared and low-level radioactive material is routinely generated from normal activities, including clothes, rags, metal equipment, concrete structures, etc. For low-level radioactive material, most of this material can be freed from its added radioactivity through survey and simple cleanup (decontamination if necessary). When properly managed and regulated these activities pose no real health issues for people or the environment. It is understandable that there are increasing public demands and expectations for the reuse and recycling of valuable resources, which nuclear - like many other sectors - can no longer ignore. There are efficiencies to be found through technical solutions (resulting in waste volume reductions, better sorting of waste, etc.), which would enable mitigation of environmental impacts and increased preservation of these natural resources. In addition, it will reduce volumes for storage and disposal which are rare resources. There must be a balance struck between the availability of disposal, and recycling and reuse, depending on the outcomes of assessments. Both the advantages in terms of preserving natural resources and disposal capacity should enable the industry to gain credibility with stakeholders. Taking Europe as an example, excellence in the implementation of the reuse and recycling of metals and of disposal of very-low waste, would, if widely shared between countries, no doubt lead to greater efficiency. International and national leaders from industry, regulators and governments should enable the concurrent availability of these three safe management options in each country, worldwide. Whenever an option considered is supported by a solid industrial business case, operators and regulators can (and must) concurrently deploy and operate safe reuse, recycling and disposal. This flexible approach should be deployed; the Association is of the firm conviction that the exclusive commitment to a single option cannot be sound on any grounds. (authors)

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Performance Assessment of a Generic Nuclear Waste Repository in Shale - 18392

A performance assessment (PA) is an important component of a comprehensive safety analysis for a nuclear waste repository. In a PA, probabilistic simulations of the total repository system are performed, and results are evaluated against performance metrics. Uncertainty and sensitivity analyses help prioritize additional research and model development. The United States Department of Energy (DOE) has been developing a state of the art PA simulation software tool-kit, Geologic Disposal Safety Assessment (GDSA) Framework, that couples increasingly higher fidelity models of subsystem processes into total system PA simulations. Over the past several years, PAs of generic repositories in three geologic media (salt, shale, and crystalline rock) have demonstrated ongoing developments in capability. The current PA of a nuclear waste repository in a generic shale formation showcases GDSA Framework, including capabilities in domain discretization (Cubit), multi-physics simulations (PFLOTRAN), uncertainty and sensitivity analysis (Dakota), and visualization (Paraview). The generic shale reference case considers the disposal of 22,000 metric tons heavy metal of commercial spent nuclear fuel (SNF) in a generic shale formation. PA simulations account for the thermal load and radionuclide inventory of the waste form, components of the engineered barrier system including waste package and buffer, and components of the natural barrier system including the host rock shale and underlying and overlying stratigraphic units. Two repository layouts are considered, one for emplacement of waste packages containing 12 pressurized water reactor (PWR) assemblies, and one for 4-PWR waste package emplacement. Model domains are half-symmetry and contain between 7 and 22 million grid cells. Grid refinement captures the detail of individual waste packages, emplacement drifts, access drifts, and shafts. Simulations are run in a high-performance computing (HPC) environment on 512 or 2048 processes. The governing equations describing coupled heat and fluid flow and reactive transport are solved with PFLOTRAN, an open-source, massively parallel multiphase flow and reactive transport code. Additional simulated processes include waste package degradation; waste form dissolution; radioactive decay and ingrowth in aqueous, solid, and adsorbed phases; and a simple biosphere based on a pumping well. Simulations are run to 106 y; dose and radionuclide concentrations are observed within aquifers at a point approximately 5 km downgradient of the repository. Dakota is used to sample likely ranges of input parameters including waste form and waste package degradation rates and properties of engineered and natural materials to quantify uncertainty in predicted concentrations and sensitivity to input parameters. Given the assumptions of the reference case, results of 12-PWR and 4-PWR simulations are very similar. Dose at the pumping well 5-km downgradient of the repository does not exceed 10-9 Sv/y. I-129 is the largest contributor to dose. The dose due to Cl-36, the next largest contributor, is orders of magnitude smaller. At the pumping well, the concentration of I-129 5-km downgradient does not exceed 10-14 mol/L. Rank correlation coefficients indicate that the maximum concentration of I-129 within the aquifer is sensitive to shale (repository host rock) porosity and aquifer permeability. These results affirm that HPC-capable codes can be used to simulate important multi-physics couplings directly in a total system performance assessment of a geologic repository, and can be used in prioritization of future research and model development. (authors)

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Delivering Business Benefit to UK Decommissioning through Collaborative Innovation - Approach and Technologies - 18539

The UK's nuclear energy programme, dating from the post-war years, has left a mixed legacy to the country: numerous prototype reactors, fuel-manufacturing plants, research centres, reprocessing plants and 11 power stations. The Sellafield site in west Cumbria houses more than 200 nuclear facilities and 1,000 buildings, making it one of the world's most complex environmental decommissioning challenges. Many 'never-done-before' projects are under way, which require substantial levels of R and D and innovative engineering approaches. One of the Nuclear Decommissioning Authority's (NDA) responsibilities is to ensure that the right level of R and D is carried out to enable progress on delivering the full decommissioning programme. Since 2010, NDA has been collaborating with Innovate UK, the UK government's innovation agency, to engage the supply chain and develop innovative technologies and services to support the NDA's mission and the growing international nuclear decommissioning market. The paper will provide an overview of the approach (e.g. open calls, briefing events, independent assessment, technology showcases) and the associated benefits (e.g. attracting new ideas, end-user engagement, increased supply chain collaboration). The paper also highlights selected technologies developed through the process. (authors)

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Updating a PWR Simulator in Python

A nuclear reactor is a complicated system that is comprised of many systems and components. In order to fully model a reactor, several approximations and correlations must be used for a real-time simulation. In 1984 as part of a doctoral dissertation at Massachusetts Institute of Technology (MIT), a FORTRAN 77 program was developed to simulate a four-loop, Westinghouse pressurized water reactor (PWR). The program was later called PRISM and extended to include a comprehensive set of features accessible in a DOS-based user interface. This present work seeks to update the original PRISM program for cross platform deployment using the Python language. The goal of this present work is to update and improve a teaching tool for both students and reactor operators. Originally, PRISM was created as part of a PhD project in FORTRAN 77, but the code no longer works readily on modern operating systems. Python was chosen to rewrite the program because of the ease of use of the Python modules including Kivy as well as the portability of the program to various operating systems. This project aims to develop desktop and mobile versions of the software, allowing the user flexibility in choice of platform. This simulator is scheduled to be deployed in time for a live demonstration at the 2016 Annual ANS meeting. The project aims to produce a reactor simulator that will showcase the dynamics of a PWR system in real-time under various conditions. Some potential scenarios include startup conditions, scram operations, or failure conditions such as a break in a coolant leg. The user will be able to induce various failure scenarios and the program will simulate how the reactor will behave. The simulation will include a suite of monitoring functions that will allow automatic systems to attempt to adapt to the changing conditions, e.g., control rod movement. This program will provide an educational resource for anyone learning about nuclear reactor kinetics or dynamics of a reactor system. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Rad Waste Cost/Volume Reduction Using New Monitoring/Decon Techniques, Launderable Items and Recycling - 19297

The use of improved radiation monitoring and decontamination techniques significantly reduces the cost and volume of Canadian radioactive waste via recycling/reuse. Over 2,700 metric tons of scaffolding and tooling have been released for unrestricted use back to the owners or recycled as non-radioactive scrap metal over the last 10 years. Additionally, using reusable launderable items reduces the cost over single use Radiological Personal Protective Equipment (RPPE) and plastic wraps and has eliminated thousands of cubic meters of Canadian station waste each year for over 10 years. The combined effect is the significant volume reduction of radioactive waste in a low risk, cost effective, manner. This paper and presentation will highlight the processes and showcase the types of materials decontaminated. The intent is to make waste generators aware of new processes that could be applied to the waste materials stored in their vaults or generated during a refurbishment/decommissioning project as well as day-to-day power generation operations. (authors)

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Treatment of Foreign Radioactive Waste at the BELGOPROCESS Plant - 19345

Belgium has used a large number of nuclear technologies during the last 60 years. Power generation, reprocessing, fuel fabrication, isotope production and research activities have produced a large variety of radioactive waste streams. BELGOPROCESS is the operator of the centralised waste treatment facilities located in the Campine region in Flanders. Over the years BELGOPROCESS has developed the know-how and facilities to treat each one of these waste streams. BELGOPROCESS is a subsidiary of NIRAS, the governmental institution responsible for the safe management of radioactive waste and enriched fissile materials in Belgium. A number of these waste streams are only produced during a short period of time. After processing the existing stockpile the treatment facility is put into operational standby and eventually prepared for decommissioning. In order to treat the stockpile of some types of legacy waste within an acceptable time frame, the treatment facilities needed to be designed at a certain treatment capacity. Since the majority of the legacy waste is processed nowadays, a significant amount of treatment capacity becomes available. In June 2006 the Belgian government decided that this know-how and facilities should become available to foreign waste producers. This would allow BELGOPROCESS to fill up the available capacity of its facilities and consequently lower the cost for the Belgian waste producers. Nowadays two facilities are open to accept foreign radioactive waste. The CILVA-facility can be used for sorting, cutting, incineration, precompaction, supercompaction and cementation of low level solid waste. The PAMELA-facility - a former vitrification plant - can be used for the treatment of medium level and alpha-bearing waste. In this paper we will discuss the technical characteristics of the CILVA-incinerator and a showcase for the treatment of foreign waste at our facilities. In 2016 BELGOPROCESS started a cooperation with MATE-FIN for the incineration of low level burnable waste from the Cernavoda NPP in Romania. (authors)

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Panel Session 120B: DOE Portsmouth Paducah Project Office (PPPO) Update

This panel focused on the Portsmouth/Paducah Project Office (PPPO) of the US DOE Office of Environmental Management, Lexington, Kentucky, the US DOE Featured Site for Thursday. It showcased recent progress, challenges and planned efforts in radioactive waste management, waste disposition, environmental remediation and D and D at the Portsmouth (Ohio) and Paducah (KY) Gaseous Diffusion Plant Sites, as well as the Depleted Uranium Hexafluoride (DUF6) Conversion Project with facilities at both sites Presentations proposed include: 1 - Portsmouth/Paducah Project Office (PPPO) (Joel Bradburne, US DOE Portsmouth/Paducah Project Office (USA)); 2 - Portsmouth (Jeff Bettinger, US DOE Portsmouth/Paducah Project Office (USA)); 3 - Paducah (Jennifer Woodard, US DOE Portsmouth/Paducah Project Office (USA)); 4 - Depleted Uranium Hexafluoride Conversion Project (Reinhard Knerr, US DOE Portsmouth/Paducah Project Office (USA)); 5 - Portsmouth Deactivation and Demolition Project (Bob Smith, Fluor-BWXT Portsmouth (USA)); 6 - Paducah Deactivation and Remediation Project (Jeff Bradford, Four Rivers Nuclear Partnership - FRNP (USA)); 7 - Seven Lines-One Project (Zack Smith, SNC Lavalin (USA))

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

A Data Processing Workflow for Fixed-wing Drone Based Radiation Mapping in the Chornobyl Exclusion Zone (CEZ) - 20119

April 2020 marks the 34. anniversary of the high-profile radiological release from the Chornobyl Nuclear Power Plant (ChNPP). The release of radioactive material from reactor number four began on the 26 April 1986 and continued over a period of about 10 days, releasing approximately 1700 PBq of radioactive material (including 85 PBq of 137-Cs) into the environment. To this day, the accident remains the most significant release of radioactive material since civil nuclear power generation began. In the years since the accident, automated and remote radiation monitoring technologies have advanced significantly in their capabilities. One such example of this is the use of unmanned aerial vehicles (UAVs) in radiation mapping investigations. In April 2019, a team of scientists from the University of Bristol showcased a novel radiation mapping system within the CEZ, specifically aiming to map radiation over a large portion of the area immediately surrounding the ChNPP. Over six days of data collection, the system flew a total distance of 583.8 km, covering an area of 14.6 sq.km with an exceptional spatial resolution (sub 20 m/pixel). The work presented herein outlines and explains the data processing procedure to convert the raw data into 137-Cs activity (kBq/sq.m) and cesium-equivalent dose-rate (CED) at 1 m above ground level (μSv/hr). A demonstration of the validity of the method is demonstrated through the successful reduction of the raw data into a single linear relationship between the measured {sup 137}Cs net peak intensity and the {sup 137}Cs activity. (authors)

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German HTR phase out - experience and remaining challenges - 18659

For more than 50 years the pebble bed High Temperature Reactor (HTR) is under development in Germany. Forschungszentrum Juelich, Aachen University, but also industrial companies and other organizations are, respectively were involved in this task, which was for about two decades something like a national showcase. More than ten years before the German decision to shut down all nuclear power plants in Germany there was a strong decrease in the interest on HTR-related activities. Reasons might be the lack of competitiveness of HTRs for electricity production only in a well-developed grid, the bad performance of the German demonstration plant THTR and the rapid increase of the general German Angst. Most of the ongoing HTR activities will come to an end in a relatively short time. Last experimental projects cover the graphite dust behavior. The analytical work is focused on the further development of the HTR Code Package (HCP). In this paper, the German experience, remaining challenges and lessons learned will be addressed. Especially aspects such as fuel fabrication and qualification, the performance of AVR and THTR, the HTR-Modul concept, economic aspects of HTR, the competition and/or complementarities to LWR, the statement of inherent HTR safety and the development of large components for turbine, steam generator, blower and bearings will be presented. (authors)

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Secondary neutron yields from thick-target GCR accelerator experiments - 25434

This work overviews recent experiments conducted at the NASA Space Radiation Laboratory which sought to experimentally verify model predictions of an optimal spacecraft shielding thickness and provide data which can be used to quantify uncertainties in the physics models within the standard particle transport codes which presently, in some places, poorly predict data and whose results can vary significantly from code to code. Now that the multi-year experiment campaign is complete, some of the overarching trends in the data can be studied; though this work only provides a cursory look at these overarching trends. A small set of the neutron yields measured in these experiments are showcased here. The experiment employed two thick targets along a beamline to emulate the walls of a spacecraft being bombarded by galactic cosmic rays. Time-of-flight techniques were used to characterize neutrons produced in the upstream target while a novel pulse height deconvolution methodology was developed and implemented to characterize neutrons produced in the downstream target. (authors)

43 PARTICLE ACCELERATORS↗

Thermal feedback coupling in a transient Monte Carlo high-order/low-order scheme

Transient simulations of nuclear systems face the computational challenge of resolving both space and time during reactivity changes. A common strategy for tackling this issue is to split the neutron flux into shape and amplitude functions. This split can be solved with high- order/low-order methods. While this multi-fidelity approach has traditionally been reserved for deterministic methods, it is also possible to implement in Monte Carlo as an efficient alternative to Dynamic Monte Carlo. This work implements the frequency transform method with thermal feedback in high-order/low-order Monte Carlo by blending static coupling methods such as single-batch Monte Carlo, with a simple thermal-fluids calculation. While previous work focused solely on prescribed transients, the addition of time-dependent thermal-fluids allows transients to be self-propagating. Tests were run in a fluids-initiated transient to showcase the basic functionalities of this methodology. Preliminary results behave as expected, paving the way for studying more sophisticated thermal-fluids coupling methods. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Development of the MCNP-ORIGEN activation automation tool

This paper introduces the MCNP-ORIGEN activation automation tool for streamlining the calculation of experiment source terms. This tool couples the Monte-Carlo radiation-transport solver, MCNP to the depletion tool, ORIGEN-S. To showcase its current capabilities, this paper presents an activation analysis exercise, which is conducted with Serpent, and the results are com- pared. The experiment consists in a 90%-enriched uranium sphere surrounded by light water. A non-fissile cylinder is placed in the water, representing an irradiation experiment. We conducted simulations for 2 different cylinder materials: iron and cobalt at two different temperatures: 300 K and 900 K. The exercise consists of an irradiation of 50 days at a constant power of 5 MW, followed by a decay of 50 days. These studies highlight the discrepancies between how the different tools handle nuclear data. Finally, the results underscore multiple areas of possible improvement.

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