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DOE OSTI2019

Spent Nuclear Fuel and High-Level Radioactive Waste Inventory Report

This report provides information on the inventory of commercial spent fuel (SNF) and high-level radioactive waste (HLW) in the United States, as well as non-commercial SNF and HLW in the U.S. Department of Energy (DOE) complex. Actual or estimated quantitative values for current inventories are provided along with inventory forecasts derived from examining different future commercial nuclear power generation scenarios. The report also includes select information on the characteristics associated with the wastes examined (e.g., type, packaging, heat generation rate, decay curves). This report was produced for the U.S. Department of Energy (DOE) to support various analyses on options for storage and transport of SNF and HLW and sponsored by DOE’s Office of Spent Fuel and Waste Disposition (SFWD). The report draws from and complements a previously issued report, Fuel Cycle Potential Waste Inventory for Disposition, developed for DOE’s Used Nuclear Fuel Research & Development Campaign. The current report is not intended as a revision to either Fuel Cycle Potential Waste Inventory for Disposition or Evaluation of Options for Permanent Geologic Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste in Support of a Comprehensive National Nuclear Fuel Cycle Strategy from which some underlying data is used as referenced in the current report. Rather, this report is intended as a stand-alone report providing estimates of current and projected SNF and HLW inventory and has been generated for SFWD planning purposes. This is a technical report that does not take into account contractual limitations or obligations under the Standard Contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (Standard Contract) (10 CFR Part 961). For example, under the provisions of the Standard Contract, spent nuclear fuel in multi-assembly canisters is not an acceptable waste form, absent a mutually agreed to contract amendment. To the extent discussions or recommendations in this report conflict with the provisions of the Standard Contract, the Standard Contract governs the obligations of the parties, and this report in no manner supersedes, overrides, or amends the Standard Contract. This report reflects technical work which could support future decision making by DOE. No inferences should be drawn from this report regarding future actions by DOE, which are limited both by the terms of the Standard Contract and a lack of Congressional appropriations for the Department to fulfill its obligations under the Nuclear Waste Policy Act including licensing and construction of a spent nuclear fuel repository.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Nuclear Data Assessment for Advanced Reactors

Advanced reactor concepts being developed throughout the industry are significantly different from light-water reactor (LWR) designs with respect to geometry, materials, and operating conditions, and consequently, with respect to their reactor physics behavior. Given the limited operating experience with non-LWRs, the accurate simulation of reactor physics and the quantification of associated uncertainties are important for ensuring that the nuclear design for advanced reactor concepts include appropriate margins. Nuclear data are a major source of input uncertainties in reactor physics analysis. As part of a project sponsored by the US Nuclear Regulatory Commission at Oak Ridge National Laboratory (ORNL), key nuclear data relevant to reactor safety analysis in selected advanced reactor technologies were identified, and their impacts on important key figures of merit were assessed based on (1) a review of available advanced reactor specifications, (2) analysis of previous studies performed at ORNL and other research institutions, and (3) sensitivity and uncertainty analyses performed for six selected benchmarks—three experimental and three computational—to quantify the impacts of the identified key nuclear data on several key metrics. This report summarizes the key nuclear data—nominal data and nuclear data uncertainties— considering the most important nuclear reactions in the fuel and in various materials for the moderator, coolant, and structure of the considered advanced reactors.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Exploring Advanced Computational Tools and Techniques with Artificial Intelligence and Machine Learning in Operating Nuclear Plants

This report presents the project Idaho National Laboratory conducted for Nuclear Regulatory Commission to explore the advanced computational tools and techniques, such as artificial intelligence (AI) and machine learning (ML), for operating nuclear plants. The report reviews the nuclear data sources, with the focus on the operating experience data, that could be applied by advanced computational tools and techniques. Plant-specific and generic (national and international) data from different sources are described. The report describes the relationships between statistics and AI/ML and then introduces the most widely used AI/ML algorithms in both supervised and unsupervised learning. The report reviews the recent applications of advanced computational tools and techniques in various fields of nuclear industry, such as reactor system design and analysis, plant operation and maintenance, and nuclear safety and risk analysis. Finally, the report presents the insights from the project on the potential applicability of AI/ML techniques in improving advanced computational capabilities, how the advanced tools and techniques could contribute to the understanding of safety and risk, and what information would be needed to provide meaningful insights to decision makers. The report also documents an NRC survey on the current state of commercial nuclear power operations relative to the use of AI and ML tools as well as the role of AI/ML tools in nuclear power operations was published by the NRC as in FRN NRC-2021-0048 in April 2021. A summary of the survey including the survey questions, survey participants, survey responses, and the conclusions and insights derived from the survey is provided in the report. Finally, the report investigates potential applications of using AI/ML in operating NPPs and advanced reactors (both advanced LWRs and advanced NLWRs) to improve nuclear plant safety and efficiency. Three main application fields are defined and discussed: (1) plant safety and security assessments; (2) plant degradation modeling, fault and accident diagnosis and prognosis; and (3) plant operation and maintenance efficiency improvement.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

Development of Platforms for Nuclear Science Experiments at the National Ignition Facility

When neutrons are produced in nuclear processes such as fission or fusion, they can interact with any surrounding materials, inducing radioactivity through neutron capture reactions. Neutron reactions are fundamental to many areas of nuclear science, including studies of nuclear reactors, determining the formation of matter in stars, nuclear forensics, medical radiotherapy, and assessing the safety of our nuclear stockpile. The National Ignition Facility (NIF) offers a unique opportunity to use the inertial confinement fusion platform to measure neutron reactions essential to national security or fundamental and applied science applications. A typical fusion experiment at NIF currently produces approximately 10 16 neutrons through the fusion of deuterium and tritium in a target capsule. Materials introduced into the NIF target chamber in close proximity to the capsule will undergo neutron reactions such as capture or fission, and the resultant reaction rates can be evaluated. While neutron reactions can be measured at other facilities, NIF offers unique advantages. The flux of neutrons produced (number of neutrons per square centimeter per second) is much higher than any other available neutron source due to both the small size of the NIF capsule (2-mm diameter before implosion) and the short time (roughly 100 ps) over which the neutrons are produced. This results in less target material required to perform a reaction-rate study (less than or equal to 10 16 atoms) as compared to traditional particle accelerators, which require targets that are approximately 1 mg or roughly 10 20 atoms. Also, the NIF neutron spectrum is peaked at thermonuclear (14 MeV) neutron energy, which means that nuclear reactions with nonthermal energy thresholds can be studied at NIF, whereas neutron energies at a nuclear reactor are generally insufficient for studying higher-energy neutron reactions. Several experimental configurations have been developed that enable the use of NIF fusion capsules as powerful neutron sources for nuclear reaction measurements.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2013

The Creation of a French Basic Nuclear Installation - Description of the Regulatory Process - 13293

CEA is a French government-funded technological research organization. It has to build a medium-level waste interim storage facility because the geological repository will not be available until 2025. This interim storage facility, called DIADEM, has to be available in 2017. These wastes are coming from the research facilities for spent fuel reprocessing and the dismantling of the most radioactive parts of nuclear facilities. The CEA handles the waste management by inventorying the needs and updating them regularly. The conception of the facility is mainly based on this inventory. It provides quantity and characteristics of wastes and it gives the production schedule until 2035. Beyond mass and volume, main characteristics of these radioactive wastes are chemical nature, radioisotopes, radioactivity, radiation dose, the heat emitted, corrosive or explosive gas production, etc. These characteristics provide information to study the repository safety. DIADEM mainly consists of a concrete cell, isolated from the outside, wherein stainless steel welded containers are stored, stacked in a vertical position in the racks. DIADEM is scheduled to store three types of 8 mm-thick, stainless steel cylindrical containers with an outside diameter 498 mm and height from 620 to 2120 mm. DIADEM will be a basic nuclear installation (INB in French) because of overall activity of radioactive substances stored. The creation of a French basic nuclear installation is subject to authorization according to the French law No. 2006-686 of 13 June 2006 on Transparency and Security in the Nuclear Field. The authorization takes into account the technical and financial capacities of the licensee which must allow him to conduct his project in compliance with these interests, especially to cover the costs of decommissioning the installation and conduct remediation work, and to monitor and maintain its location site or, for radioactive waste disposal installations, to cover the definitive shut-down, maintenance and surveillance expenditure. The authorization is issued by a decree adopted upon advice of the French Nuclear Safety Authority and after a public enquiry. In accordance with Decree No. 2007-1557 of November 2, 2007, the application is filed with the ministries responsible for nuclear safety and the Nuclear Safety Authority. It consists of twelve files and four records information. The favorable opinion of the Nuclear Safety Authority on the folder is required to start the public inquiry. Once the public inquiry is completed, the building permit is issued by the prefect. (authors)

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

Choosing Your Nuclear Fuel Cycle: A Life Cycle Assessment Perspective - 16425

Nuclear waste management has always been a much debated topic and a key driver for decisions within the nuclear industry. A standardised global approach has not yet been developed and at present many countries are re-considering their position. In the UK the reprocessing of Spent Nuclear Fuel is projected to stop, but no clear indication about the future approach has been given. This contribution sets out the early stages of an approach to compare the possible alternatives based on Life Cycle Assessment (LCA), which is widely used in other sectors to assess the overall environmental burdens of a product or a service across the whole life cycle - i.e. from cradle to grave. The LCA may serve to support decision-making processes within the nuclear industry and, provided that it is used in an open and transparent way, to improve public attitudes towards nuclear energy. To date few LCA studies within the nuclear industry have been carried out, the main issue being the lack of a standardised methodology to evaluate the impacts of radionuclides. The present study proposes a new framework for this purpose, and demonstrates its application in an LCA study of the current UK approach to the management of spent nuclear fuel based on specific data from plants at Sellafield. The final results of the study will show the overall environmental footprint of the reprocessing of spent nuclear fuel, in terms of both radiological and non-radiological impacts. A 'hot spot' analysis will also be performed to highlight the critical processing steps. (authors)

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

Collaborative Research Programme in Decommissioning, Immobilisation and Storage Solutions for Nuclear Waste Inventories (DISTINCTIVE) - 16466

The UK government remains committed to nuclear power as an important part of the energy generation capacity over the next 30-50 years and possibly beyond, with aspirations for both new-build power stations and lifetime extension of the existing fleet. A central component of public acceptance for any new-build programme is the need to demonstrate our ability to safely manage and dispose of high- and intermediate-level wastes from legacy nuclear operations. Clear milestones associated with the needs of waste management and decommissioning have been provided by the UK government, and most rely on further research and technical developments being delivered over the next 10-20 years. The DISTINCTIVE (Decommissioning, Immobilisation and Storage Solutions for Nuclear Waste Inventories) consortium is carrying out research that addresses the broad area of nuclear waste and decommissioning, bringing together key industry partners and leading academic researchers from 10 of the UK's leading research intensive universities. The research being carried out is multi-disciplinary and covers both fundamental and applied topics, with research projects clustered in four major themes: AGR, Magnox and exotic spent fuels; PuO{sub 2} and fuel residues; legacy ponds and silo wastes; and structural integrity. The consortium builds upon and consolidates the work of previous Research Councils' UK Energy Programme-funded projects in the same field although, importantly, this new project draws in researchers from a larger group of universities and increases the multi-disciplinary nature of the group. All participating research groups have a strong track-record of supporting the nuclear industry through basic and applied research as well as consultancy activities. Key aims of the consortium are to extend and develop a relevant academic skill base in the UK associated with the needs of the nuclear waste management industry, to train the next generation of UK researchers, equipping them with skills and experiences relevant to nuclear waste management and decommissioning issues, and to carry out cutting-edge research that has the potential to provide new and innovative pathways to better management of both legacy and future nuclear wastes. (authors)

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

Augmented Reality Tools for Nuclear Facilities - 18318

In this work we explore the possibility of improving nuclear facility operations through the use of emerging augmented reality technology. Specifically we focus on the use of augmented reality headsets. Augmented reality opens up the possibility for easy, on-the-fly access to documentation related to canisters, rooms, and carts. It also can be used to help plan complicated material moves in ways that do not violate nuclear criticality safety regulations. Modern augmented reality technology can also be interacted with using gaze, gesture and voice commands, thus making it particularly attractive for facilitating the documentation of nuclear material operations and work verification. An augmented reality-based nuclear facility criticality safety system would have a number of benefits for operations in nuclear facilities. This work could be used across the DOE complex to ensure technicians in gloveboxes work safely and securely. It could greatly reduce downtime associated with administrative criticality incidents. It would be a step forward in the process of improving the quality of documentation of the work that occurs in nuclear facilities while simultaneously increasing the ease with which this documentation can be collected. The augmented reality effectively endows the glovebox technicians with a sense for administrative nuclear criticality safety and the reactivity changes caused directly by their actions. Augmented reality also has great potential for facilitating inspections of nuclear infrastructure. Examples of Augmented Reality applications that facilitate infrastructure inspection and work verification will also be presented. (authors)

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

The Development of National Nuclear Forensics Capability in ROK - 18562

According to the IAEA, each state has to build a national nuclear forensics system to determine the origin of radioactive or nuclear materials related to nuclear terrors. Based on this, the system in ROK was proposed by the Korea Institute of Nuclear Nonproliferation and Control (KINAC). The strategy for it consists of 4 TIER; legal framework, field response, library, and analysis. The legal framework for anti-terror has been systemizing and planned to extend to the nuclear respond with reflection of nuclear threat. It does not include the role and responsibility for each TIER, which impedes the progression of lower TIER. The government makes it materialized shortly with a strong will. The field of sampling and library had many progress. These were not completed, since unexplored before. However, it is possible to expect the outcome in years by active cooperation of license holders. The field of analysis has no major progress. KINAC expects rapid progress after roles are confirmed by law, because there are research laboratories specialized in nuclear material analysis. Meanwhile, the interface with the traditional forensics is in a barren land. KINAC expects there would be ignition for the traditional forensic experts by raising awareness of the nuclear forensics, such as cooperation in the council. Through these efforts, KINAC hopes to build regulatory system without loophole. In this process, the NSSC and KINAC are aware that this process is not possible with a single agency's effort, and will strive to elicit cooperation. (authors)

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

External Engagement During Evaluations of Shutdown Nuclear Power Plant Sites - 19221

This is a technical paper that does not take into account the contractual limitations under the Standard Contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (Standard Contract) (10 CFR Part 961). Under the provisions of the Standard Contract, DOE does not consider spent nuclear fuel in multi-assembly canisters to be an acceptable waste form, absent a mutually agreed to contract amendment. To the extent discussions or recommendations in this paper conflict with the provisions of the Standard Contract, the Standard Contract provisions prevail. The U.S. Department of Energy Office of Integrated Waste Management (DOE-IWM) continues to conduct evaluations of removing spent nuclear fuel (SNF) from shutdown nuclear power plant sites. The 14 shutdown sites included in the evaluation to date have nuclear power reactors that have been permanently shut down and the sites have been decommissioned or are undergoing decommissioning. The 14 shutdown sites are Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, Zion, Crystal River, Kewaunee, San Onofre, Vermont Yankee, and Fort Calhoun. The Oyster Creek Nuclear Generating Station ceased operations in September 2018 and will be included in future evaluations. A key part of the shutdown site evaluations are visits to the sites. These site visits typically take place over 3 days. The first day is spent at the nuclear power plant site. The second day is spent evaluating the near-site transportation infrastructure, including rail infrastructure, potential heavy-haul routes, and potential rail and barge transload locations. The third day is often spent meeting with community engagement or advisory panels. External engagement activities during site visits are conducted in two areas. The first area involves inviting tribal and state representatives, State Regional Group (SRG) representatives, and Federal Railroad Administration (FRA) representatives to participate in the entire site visit. The SRG representatives are from the Southern States Energy Board, the Western Interstate Energy Board, the Council of State Governments - Midwest, or the Council of State Governments - Eastern Regional Conference, according to the location of the nuclear power plant. State representatives typically represent their state department of energy, state department of environmental or natural resources, State Rail Safety Participation Program, state police, state department of transportation, radiation protection organization, or emergency management organization. Tribal representatives explore issues associated with cultural affiliation and tribal involvement with past and present site activities. As the regulator of the U.S. railroads, the FRA representatives bring unique experience to the site visits. They also coordinate meetings with the railroads that serve the shutdown sites. The second area of external engagement activities during site visits involves meeting with local community engagement or advisory panels. Meeting with local community engagement or advisory panels provides an opportunity to inform these panels on DOE activities and the roles and responsibilities of federal agencies during site decommissioning. (authors)

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

Regulatory Basis for Dry Spent Nuclear Fuel Storage Canister Inspections

Nuclear power plants in the United States began moving Spent Nuclear Fuel (SNF) from wet storage to dry storage in Independent Spent Fuel Storage Installations (ISFSIs) in 1986 at Surry station in Virginia. Dry storage represented an innovative solution to the problem created by the U.S. government's failure to fulfill its obligation to begin removing SNF from power plant sites. Today, about 70 ISFSIs have been placed into operation on the sites of current, or former nuclear power plants. There are currently over 2,200 SNF dry storage systems (DSSs) in service at these locations. Thirteen of these ISFSIs are located at sites with no operating reactor, and this number is due to increase in the coming years. Operating nuclear power stations use ISFSI storage to maintain wet storage capacity for recently discharged SNF. Permanently shutdown nuclear power plants use ISFSI storage to allow decommissioning and dismantlement of the power plant structures, systems, and components. The U.S. Nuclear Regulatory Commission (NRC) regulates the licensing, construction, and operation of ISFSIs under Title 10 of the U.S. Code of Federal Regulations, Energy, Part 72, Licensing Requirements for the Independent Storage of Spent Nuclear Fuel, High-Level Radioactive Waste, and Reactor-Related Greater than Class-C Waste (10 CFR 72). When the regulations in 10 CFR 72 were created around 1980, 20 years was chosen by the NRC as the license term for a specific ISFSI license and later, for a DSS Certificate of Compliance (CoC). Twenty years was, at the time, believed to be a sufficient time period for on-site interim dry storage of spent nuclear fuel before the U.S. government began moving the spent fuel away from the plant site for final disposal. Little, if any consideration was given to providing a regulatory framework for extending ISFSI licenses and DSS CoCs beyond 20 years at that time. However, shortly after the turn of the century, with still no federal program for removing SNF from reactor sites on the near-term horizon it became apparent that most DSSs would be required to remain in service at the ISFSIs beyond the initial 20-year license term. Operation beyond the original license term requires the specific license or the DSS CoC (used at a general license ISFSI) to be renewed. The requirements for renewal of a specific ISFSI license or a DSS CoC include addressing age-related degradation of structures, systems, and components that perform or support safety functions. (authors)

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

Nuclear criticality safety in the United Kingdom - Work In progress

Full text of publication follows: This commentary presents a brief overview of the recent and future challenges and opportunities presented by the UK nuclear industry. To give just a pure overview would lead perhaps to a rather dry and superficial review, so I have mixed in with this my own thoughts and coloured it with some of my opinions and observations from involvement in the field of Nuclear Criticality Safety (NCS) over the last 26 years. A brief overview of industry status and developments in the UK will, however, be highlighted, in order to give a background to what I hope would be an interesting personal commentary on the subject. The creation of the Nuclear Decommissioning Authority (NDA) in 2004 have (on behalf of the UK governments Department for Energy and Climate Change (DECC)) pursued the mission to 'deliver safe and sustainable solutions to the challenge of nuclear clean-up and waste management'. NDA have responsibilities for 17 of the civil nuclear facilities in the UK. This has meant for the UK nuclear industry, and in turn UK Criticality Safety, the significant focus toward safe, efficient and effective clean-up. With this mission, integrated with the ongoing commercial ventures at many of the UK licensed sites, a great variety of challenges are presented. For non-commercial activities, criticality safety has and will continue to have a significant future part to play. The UK government's commitment to a continued nuclear defense capacity ensures a major investment in the future and will continue to demand significant capability from criticality safety to support the existing commitments and future needs. Meeting these challenges demands a holistic approach to criticality safety if it is to succeed in supporting the continued safety of the industry. Technical solutions to the challenges are only part of the solution. Maintaining a technical competency, working as part of an integrated team with other safety disciplines, along with the design teams and operations management etc. are other important aspects. Working collaboratively within these teams and beyond, both nationally and internationally, is a necessary part of achieving success. Nuclear criticality safety as a discipline in the UK has always been conscious of isolation and stagnation in development given the relatively small number of personnel in the criticality field. With this concern, it benefits immensely from national and international collaboration, and this must be encouraged to continue. (author)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

Nuclear energy: Where do we go from here?

As Malaysia progresses towards 2020, the depleting resource of oil and gas has forced a re-look at alternatives to replace fossil fuels as energy sources. Among the viable options is nuclear energy, enabling us to meet energy needs and sustain national development in the twenty-first century. Three essential steps Malaysia must take to introduce nuclear power into its energy mix are: energy planning, infrastructure development, and deployment. Malaysia has to face a series of challenges, including public acceptance, waste management, minimizing proliferation risk, and ensuring the security of nuclear plants and materials. Timely development of qualified and competent manpower is a key limiting factor in the development and transfer of nuclear technologies — and education and training take time, effort and money. There is a need for political will. Within the Asian region, China, Korea and Japan are in the forefront in utilizing nuclear power to meet electricity demands. Countries such as UAE, Bangladesh, Vietnam and Turkey are moving ahead with the nuclear option for electricity generation and they have begun planning and construction of nuclear power plants. Against this backdrop, what are Malaysia’s moves? This paper discusses various options and challenges, obstacles and repercussions in meeting future energy demands.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2026

From Spin to Pseudospin Symmetry: The Origin of Magic Numbers in Nuclear Structure

Magic numbers lie at the heart of nuclear structure, reflecting enhanced stability in nuclei with closed shells. While the emergence of magic numbers beyond 20 is commonly attributed to strong spin-orbit coupling, the microscopic origin of the spin-orbit potential remains elusive, owing to its dependence on the resolution scale and renormalization scheme of nuclear forces. Here, we investigate the evolution of nuclear shell structure with varying momentum resolution in nuclear interactions derived from chiral effective field theory, using the similarity renormalization group to link different scales. We uncover a novel transition from spin symmetry to pseudospin symmetry as the resolution scale decreases, during which magic numbers emerge naturally. A similar pattern is found in calculations using relativistic one-boson-exchange potentials, underscoring the robustness of the phenomenon. This establishes a direct connection between realistic nuclear forces with a high resolution scale and effective nuclear forces at coarse-grained scales, offering a first-principles explanation for the origin of magic numbers and pseudospin symmetry in nuclear shell structure and new insights into the structure of exotic nuclei far from stability

Energy levels↗
DOE OSTI2021

Entanglement rearrangement in self-consistent nuclear structure calculations

Background: Entanglement plays a central role in a diverse array of increasingly important research areas, including quantum computation, simulation, measurement, sensing, and communication. Extensive suites of investigations have been performed to better understand entanglement in atomic and molecular quantum many-body systems, while the exploration of entanglement in the structure of nuclei and their reactions is presently in its infancy. Purpose: The goal of this work is to begin investigating the entanglement properties of nuclei from first-principles nuclear many-body calculations. We attempt to identify common features and emergent structures of entanglement that could ultimately lead to new and natural many-body schemes. With an eye toward quantum accelerators in future hybrid-supercomputers, criteria for partitioning nuclear many-body calculations into quantum and classical components may provide advantages in future large-scale computations. Along the way we look for explanations of the relative success of phenomenological models such as the nuclear shell model, and for better ways to match to low-energy nuclear effective field theories and lattice QCD calculations to nuclear many-body techniques that are based upon entanglement. Method: We explore the entanglement between single-particle states in 4 He and 6 He. The patterns of entanglement emerging from different single-particle bases are compared, and possible links with the convergence of observables are explored, in particular, ground-state energies. The nuclear wave functions are obtained by performing active-space no-core configuration-interaction calculations using a two-body nucleon-nucleon interaction derived from chiral effective field theory. Entanglement measures within single-particle bases exhibiting different degrees of complexity are determined, in particular, harmonic oscillator (HO), Hartree-Fock (HF), natural (NAT) and variational natural (VNAT) bases. Specifically, single-orbital entanglement entropy, two-orbital mutual information, and negativity are studied. Results: The entanglement structures in 4 He and 6 He are found to be more localized within NAT and VNAT bases than within a HO basis for the optimal HO parameters we have worked with. In particular a core-valence structure clearly emerges from the full no-core calculation of 6 He. Here, the two-nucleon mutual information shows that the VNAT basis, which typically exhibits good convergence properties, effectively decouples the active and inactive spaces. Conclusions: Measures of one- and two-nucleon entanglement are found to be useful in analyzing the structure of nuclear wave functions, in particular the efficacy of basis states, and may provide useful metrics toward developing more efficient schemes for ab initio computations of the structure and reactions of nuclei, and quantum many-body systems more generally.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Quantum simulations of nuclear resonances with variational methods

Background: The many-body nature of nuclear physics problems poses significant computational challenges. These challenges become even more pronounced when studying the resonance states of nuclear systems, which are governed by the non-Hermitian Hamiltonian. Quantum computing, particularly for quantum many-body systems, offers a promising alternative, especially within the constraints of current noisy intermediate-scale quantum (NISQ) devices. Purpose: This work aims to simulate nuclear resonances using quantum algorithms by developing a variational framework compatible with non-Hermitian Hamiltonians and implementing it fully on a quantum simulator. Methods: We employ the complex scaling technique to extract resonance positions classically and adapt it for quantum simulations using a two-step algorithm. First, we transform the non-Hermitian Hamiltonian into a Hermitian form by using the energy variance as a cost function within a variational framework. Second, we perform 𝜃-trajectory calculations to determine optimal resonance positions in the complex energy plane. To address resource constraints on NISQ devices, we utilize Gray code (GC) encoding to reduce qubit requirements. Results: We first validate our approach using a schematic potential model that mimics a nuclear potential, successfully reproducing known resonance energies with high fidelity. We then extend the method to a more realistic 𝛼−𝛼 nuclear potential and compute the 𝐷- and 𝐺-wave resonance energies with a basis size of 𝑁=16, using only four qubits. The quantum simulation results closely match the classical values, demonstrating the feasibility of our approach. Conclusions: This study demonstrates, for the first time, that the complete 𝜃-trajectory method can be implemented on a quantum computer without relying on any classical input beyond the Hamiltonian. The results establish a scalable and efficient quantum framework for simulating resonance phenomena in nuclear systems. This work represents a significant step toward quantum simulations of open quantum systems and lays the foundation for future investigations into resonance structures in nuclear, atomic, and molecular physics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Evaluating Nuclear Forensic Signatures for Advanced Reactor Deployment: A Research Priority Assessment

The development and deployment of a new generation of nuclear reactors necessitates a thorough evaluation of techniques used to characterize nuclear materials for nuclear forensic applications. Advanced fuels proposed for use in these reactors present both challenges and opportunities for the nuclear forensic field. Many efforts in pre-detonation nuclear forensics are currently focused on the analysis of uranium oxides, uranium ore concentrates, and fuel pellets since these materials have historically been found outside of regulatory control. The increasing use of TRISO particles, metal fuels, molten fuel salts, and novel ceramic fuels will require an expansion of the current nuclear forensic suite of signatures to accommodate the different physical dimensions, chemical compositions, and material properties of these advanced fuel forms. In this work, a semi-quantitative priority scoring system is introduced to identify the order in which the nuclear forensics community should pursue research and development on material signatures for advanced reactor designs. This scoring system was applied to propose the following priority ranking of six major advanced reactor categories: (1) molten salt reactor (MSR), (2) liquid metal-cooled reactor (LMR), (3) very-high-temperature reactor (VHTR), (4) fluoride-salt-cooled high-temperature reactor (FHR), (5) gas-cooled fast reactor (GFR), and (6) supercritical water-cooled reactor (SWCR).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Use of InSpector{sup TM} 1 1000 Instrument with LaBr{sub 3} for Nuclear Criticality Safety (NCS) Applications at the Westinghouse Hematite Decommissioning Project (HDP) - 13132

The Westinghouse Hematite Decommissioning Project (HDP) is a former nuclear fuel cycle facility that is currently undergoing decommissioning. One aspect of the decommissioning scope is remediation of buried nuclear waste in unlined burial pits. The current Nuclear Criticality Safety program relies on application of criticality controls based on radiological setpoints from a 2 x 2 Sodium Iodide (NaI) detector. Because of the nature of the material buried (Low Enriched Uranium (LEU), depleted uranium, thorium, and radium) and the stringent threshold for application of criticality controls based on waste management (0.1 g {sup 235}U/L), a better method for {sup 235}U identification and quantification has been developed. This paper outlines the early stages of a quick, in-field nuclear material assay and {sup 235}U mass estimation process currently being deployed at HDP. Nuclear material initially classified such that NCS controls are necessary can be demonstrated not to require such controls and dispositioned as desired by project operations. Using Monte Carlo techniques and a high resolution Lanthanum Bromide (LaBr) detector with portable Multi-Channel Analyzer (MCA), a bounding {sup 235}U mass is assigned to basic geometries of nuclear material as it is excavated. The deployment of these methods and techniques has saved large amounts of time and money in the nuclear material remediation process. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗