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413 records · Page 23

The German product quality control of the compacted metallic nuclear waste - 15311

The treatment and safe disposal of spent nuclear fuel is a key challenge of nuclear energy utilization and has to be accomplished regardless the future nuclear of electricity production or phase-out policies. Until June 2005 approx. 6662 tons of spent fuel from German nuclear power plants was sent to the La Hague (France) and Sellafield (UK) plants for reprocessing. An equivalent amount of nuclear waste compounds has contractually to be returned to Germany, which is currently in progress. The returnable waste streams comprise mainly highly-active vitrified waste containing a major part of fission products and actinides, and intermediate-active super-compacted metallic waste containing reprocessed fuel element's structural materials and some technological waste from the reprocessing process itself. Shearing and dissolution of spent fuel leaves scraps of fuel metal cladding, the end-pieces and spacers which are contaminated, activated and irradiating from their life in a reactor core. In fact, this metallic intermediate level radioactive waste makes up a bit more than half of the total volume of the reprocessed waste. At La Hague the metallic waste is super-compacted. Several, typically eight, compacted discs are stacked in a stainless steel container, named CSD-C as for 'Colis Standard de Dechets Compactes'. 4104 containers of such CSD-Cs in 152 transport/storages casks have to be returned to Germany. Each one of them has to be checked and quality certified for its conformity with German national product specifications and acceptance criteria by independent national product quality control inspectors (PKS). The residue package documentation has to be complete and the characterization methods have to be comprehensive. Due to the heterogeneity of metallic waste the characterization and control of its properties is very complex. The nuclear characterization is performed by means of non-destructive measurements, where only a few key nuclides are measured directly. In fact, the proper calculation of the whole nuclear inventory relies on numerous supplementary simulations. The measurement and calculation methodology is scrutinized by PKS in detail and key points are benchmarked with our own simulations for the sake of an independent nuclear inventory declaration check. With respect to the vast amount of documentation and parameters, which have to be checked and verified, PKS had to optimize their checking procedures. For this purpose dedicated proof tools have been developed that shall be applied for selected indicative cross-checks of the relevant parameters. This contribution is dedicated to the procedure of quality control by PKS and examples of actually performed computational verifications of declared nuclear inventory. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Knowledge Management in Nuclear Liabilities Regulation in the UK - 18155

Within the UK's nuclear safety regulator (Office for Nuclear Regulation; ONR) nuclear liabilities regulation addresses the safe management of radioactive waste, decommissioning and land quality through a facility's lifetime. Higher activity radioactive waste (HAW) could be stored on site for up to 150 years prior to disposal, Magnox decommissioning sites are planned to be in Care and Maintenance for up to 70 years and Sellafield decommissioning is not planned to be complete until after 2100. The long timescales over which decommissioning occurs and radioactive waste is managed is a challenge to maintaining a suitable level of knowledge to effectively and efficiently regulate nuclear liabilities activities. There is a danger that implicit knowledge accumulated over decades could be lost as people retire. Effective knowledge capture and transfer are key elements in maintaining a workforce with the capacity and capability to deliver high levels of nuclear safety, given the demographics of the UK nuclear industry. Maintenance of recorded information over long timescales with changing technologies is necessary to allow safe storage and disposal of waste and intelligent response to incidents. As the safety regulator, ONR's ability to influence improvement in nuclear safety relies on our inspectors having access to high quality knowledge. The ONR Strategy 2016-2020 [1,2] commits to continue to recruit, retain and develop staff so that we have a core workforce with the capacity and capability to deliver high quality, enabling nuclear regulation. Over the next 30 years, the UK plans to develop a geological disposal facility and UK EDF power stations will transition into decommissioning. The ONR Knowledge Management Strategy sets out the activities planned to maintain specialist knowledge to support staff development and build organisational resilience. Guidance on waste management is given in 'The management of higher activity radioactive waste on nuclear licensed sites' (referred to as the Joint Guidance [3]) published by ONR and the UK environmental regulators. It includes our expectations for managing information and records relating to radioactive waste, and introduces the concept of Radioactive Waste Management Cases (RWMCs). Our expectation is that knowledge and records must both be managed and transferred in such a way that future licensees are properly equipped to ensure that waste continues to be managed in a manner that prevents or minimises hazards to human health and the environment. RWMCs are an effective vehicle for demonstrating how the key elements of long-term safety and environmental performance will be delivered over the life cycle of the waste. They give a history of how the waste has been managed, capturing information and change over time. This paper will look at the challenges to managing knowledge in the UK nuclear industry, focusing on the safe management of radioactive waste, decommissioning and land quality. It will look at the problems faced by both licensees and ONR, drawing out common challenges. The paper will outline the approach taken within ONR to capture and communicate waste management and decommissioning knowledge and experience. Finally, it will look at how ONR regulates and influences how knowledge and records are dealt with in the industry to ensure safe nuclear liabilities management in the long term. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

The Safe Guards Analysis Toolbox for Non-Proliferation Modeling

As nuclear technology becomes more widely available outside of nuclear weapon armed nations, the importance of preventing the illicit development of nuclear weapons has increased dramatically. A system of nuclear safeguards prevents proliferation; stopping the diversion of nuclear material from civilian facilities for the construction of nuclear weapons. These safeguards function through a combination of accountancy measurements that confirm the locations and amounts of nuclear material, and physical security at every nuclear facility. Safeguards Analysis (SGA) is a computational tool-kit developed using the MATLAB Simulink software suite that simulates a system of nuclear safeguards. The code allows users to examine current safeguards systems for weaknesses and to pinpoint the best locations for improvement. Developed as a modular framework, SGA does not directly model material flows, and relies on an outside code for this information. Instead, it represents a series of safeguards measurements that represent the values inspectors would see. Furthermore, SGA is designed to be modular in design, allowing the user to construct as complex or simple a model as needed: simulating an entire fuel-cycle comprising multiple facilities to a single measurement. SGA's use of outside codes for its material flow information makes it applicable to any model available to the user, as opposed to previous work that applied only to a single scenario. This paper discusses the initial development of SGA and the testing of these modules. The tests described in this paper demonstrate that the different pieces of SGA currently work as intended. Future work on the toolbox will develop and test SGA against a more realistic and complicated scenario using the various tools available in SGA. SGA currently has the pieces to perform analysis on safeguards systems, but needs to be tested on large, multi-MBA, systems to ensure the code is capable of handling such large models, to see the effect large models have on calculation speed, and if further work is needed to improve code efficiency. (authors)

97 MATHEMATICS AND COMPUTING↗

Safeguards Lessons Learned from the Rokkasho Reprocessing Plant - 19502

Once operational, the Rokkasho Reprocessing Plant (RRP) will have an operating throughput of 800 MT of uranium in irradiated LWR fuel per year. In order to establish effective and efficient safeguards at RRP, the safeguards discussion with the IAEA was initiated in 1988. However, at that time there were no available models or guidelines that could be used as a reference and multiple difficulties were recognized for the implementation of safeguards into a large scale reprocessing plant. Therefore, from 1988 to 1992, a multinational forum, referred to as LASCAR (Large Scale Reprocessing Plant Safeguards) [1], provided the recommendations on how an effective safeguards approach could be implemented into a large scale reprocessing plant while efficiently using existing resources. During the course of safeguards discussions between the IAEA, the State, and JNFL, the use of operator's equipment and measurement systems (by signal splitting with authentication) for inspections was studied. JNFL also examined incorporating inspection requirements into the process design: to reduce the costs associated with system installation and future system maintenance and to ensure effective, efficient, and credible safeguards implementation into the RRP (this approach has essentially become the 'Safeguards by Design (SBD)' process). From these studies and JNFL's experience of implementing safeguards into a new plant [2], JNFL established and applied signal splitting from operator's equipment as a means for providing inspectors required safeguards information. In addition, the LASCAR findings were utilized to establish the safeguards implemented into the RRP. Safeguards implementation into RRP commenced March 31, 2006. On June 4, 2008, the IAEA approved the 'integrated safeguards approach' for RRP. This paper provides a high level overview of the major safeguards implemented at RRP and the lessons learned from this implementation that can be applied to existing or future similar facilities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Fortifying Environmental Compliance Strategies at Hanford - 19541

At the Hanford Site, located near Richland, Washington, the Department of Energy is cleaning up legacy radioactive and mixed-waste generated from the Manhattan Project in the 1940's. A major component of cleaning up the waste is maintaining compliance with federal and state environmental regulations. Environmental compliance is also determined through permits, agreements, and consent orders issued by regulating agencies such as the Washington State Department of Health: Office of Radiation Protection, Washington State Department of Ecology Nuclear Waste Program, and the Environmental Protection Agency. Maintaining compliance at Hanford reduces environmental impacts and addresses violations, or non-compliances. The following strategies improve compliance and support the avoidance of enforcement actions. At Hanford, regulatory agency environmental enforcement actions, and their corrective actions, are tracked to completion using databases maintained by inspection subject matter experts. The databases are used to provide the Department of Energy and contractor management with up-to-date status of regulatory agency activity and the required corrective actions. Trending enforcement actions helps target compliance vulnerabilities. Findings and corrective actions that are entered into the databases are then trended by date, location, responsible contractor, agency, and type of compliance issue. The ability to review previous non-compliances in certain locations of the Site, or by general alleged violation, provides the project's environmental contacts with information on what types of issues to look for on pre-inspection walk downs. Finding non-compliances during pre-inspection walk downs allows the contractor to correct the issue and avoid potential fines from regulating agencies. The walk downs are conducted by environmental specialists and project personnel looking for issues that may be viewed as a compliance problem. Using agency checklists and previous inspection correspondence can help to provide valuable information during pre-inspection activities. Training regulatory agency inspectors on Site security requirements, cultural and ecological standards, and inspection protocols allows for increased efficiency and reduces potential miscommunication between regulatory agencies and the regulated contractors. The training also allows the contractors to give the regulating agencies the up-to-date policies and procedures that will be addressed during the inspection. Hanford has pre-identified inspection coordinators within each contractor to assist in coordinating with Department of Energy personnel, projects, and management prior to the inspections. These inspection coordinators notify affected management, accommodate and escort the regulators to locations they ask to inspect, set up requested interviews, and gather requested information that will need to be cleared for public release. These practices make for positive experiences and interactions with the regulating agency personnel and help reduce and eliminate environmental non-compliances, findings, violations, and fines. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

UK regulatory review of the double contingency principle in criticality safety - 14379

The UK's regulatory regime is based on Licence Conditions (LCs) attached to a Nuclear Site Licence (NSL) and is non-prescriptive in nature. The law requires licensees to reduce health and safety risks to workers and the public 'so far as is reasonability practicable' (SFAIRP), and this framework provides licensees with flexibility to achieve this. Guidance for inspectors on the assessment of nuclear safety cases has been published in Office for Nuclear Regulation's (ONR) Safety Assessment Principles (SAPs) and supporting Technical Assessment Guides (TAGs). These guidance documents have recently been reviewed in the light of the Fukushima accident. The opportunity has also been taken to reconsider the use of the Double Contingency Principle used in criticality safety cases, an approach commonly regarded as the preferred means of criticality control internationally and featured in the SAPs and TAGs. Licensees in the UK have adopted several approaches in nuclear criticality safety cases based upon a combination of deterministic and probabilistic safety cases using the Double Contingency Principle and Design Basis Analysis. ONR has developed a targeted intervention to sample a number of nuclear safety cases in order to test the adequacy of methodologies used to secure nuclear criticality safety. This paper reports the results of this intervention and considers the need to review the advice currently given by the UK nuclear regulator, including on use of the Double Contingency Principle. (authors)

42 ENGINEERING↗

A Discrete Event Simulation Approach to Nuclear Arms Enterprise Modeling and Analysis

We overview a discrete event simulation of an arms control enterprise developed to familiarize individuals with the challenges of verification and monitoring at the enterprise level. We will review the design of the simulation applied to a notional country’s nuclear arms enterprise. This simulation models how these nuclear weapons move over their lifetime from deployment, storage, maintenance, and dismantlement. With this output information, we then characterize the “ground truth” of the enterprise. Next, based on these data, we built a sophisticated analysis engine designed to provide treaty monitoring and verification information to support partner country inspectors and their evaluation. This tool was designed to be used as a game, enabling teams to compete on developing the best inspection plan to determine if the host country is complying with the conceptual treaty developed for this effort.

Pulliam, Rachel M.↗

Novel Photonuclear Methods to Produce an Argon-37 Standard

The mission of this research is to explore novel photonuclear-based pathways into the production of 37Ar. Above-background detection levels of 37Ar uniquely indicates the occurrence of an underground nuclear explosion, produced from fission neutrons interacting in the surrounding environment through the 40Ca(n,a)37Ar reaction. The half-life of 35 days allows on-site inspectors (OSI) adequate time following the nuclear event to detect 37Ar and verify compliance or defiance of non-proliferation treaties such as the Comprehensive Nuclear-Test-Ban Treaty (CTBT). An 37Ar standard would give OSI the ability to calibrate their detectors and measure detector efficiency allowing for the quantification of detected activity, give OSI authentic samples to test detectors in field exercises, and improve models predicting diffusion pathways of 37Ar through the underground environment.

43 PARTICLE ACCELERATORS↗

Evaluation of Machine Learning Models for Automated Data Analysis in In-Service Nuclear Power Plant Inspections

The commercial nuclear power industry is facing a potential shortage of certified nondestructive evaluation (NDE) analysts to meet future in-service inspection demands. Automated data analysis (ADA) currently supports human inspectors in tasks such as eddy current evaluations for steam generator examinations. Machine learning (ML) systems are nearing the capability to pass performance demonstration tests for ultrasonic testing (UT) inspections of reactor pressure vessel upper head penetrations in nuclear power plants (NPPs). Current research and development is focused on assisted analysis (AA) of ADA versus fully automated examinations. This presentation will cover assessment of ML flaw detection on dissimilar metal weld (DMW) piping joints.

36 MATERIALS SCIENCE↗

SURVEILLANCE DETECTION FOR TRANSPORTATION OPERATIONS PERSONNEL TO PREVENT HIJACKING, THEFT, SABOTAGE, AND MALICIOUS SECURITY EVENTS DURING TRANSPORTING NUCLEAR MATERIAL

The secure transportation of high-consequence materials, including nuclear and radiological assets, is a critical global priority in the face of escalating terrorism, security threats, and violent protests targeting these operations. Effective surveillance detection—the ability to identify, assess, and respond to potential threats across a continuum of scenarios—is paramount in addressing these challenges. This paper outlines a phased, multi-tiered training program designed to strengthen the surveillance detection capabilities of organizations responsible for nuclear material transport. The proposed training program adopts a progressive approach, gradually increasing in technical complexity to provide participants with comprehensive knowledge and tools for implementing robust security strategies. It targets a wide spectrum of stakeholders, including competent authorities, regulators, inspectors, shippers, carriers, law enforcement, and emergency response personnel, equipping them to plan, evaluate, and safeguard nuclear material transportation effectively. Each phase of the program emphasizes distinct elements of the surveillance detection continuum and transport security, focusing on critical topics such as threat identification, adversary task timelines, protective methodologies, and attack mitigation strategies. The training framework is anchored in technical exchanges and scenario-driven courses that reflect real-world complexities and challenges. By addressing the surveillance detection continuum comprehensively—from early threat assessment to active countermeasures—the program reinforces global efforts to secure nuclear assets. It aligns with international security objectives and fosters a strong security culture within participating organizations, ensuring personnel are prepared to counter potential threats and maintain the safe, secure movement of these materials. Ultimately, this initiative aims to enhance preparedness, security, and response capabilities, supporting the global mission to safeguard high-consequence materials against evolving threats.

Zineddin, Dr. Z. [ORNL] (ORCID:0009000848740725)↗

Optimization of In-Field Alpha Spectrometry for Uranium Enrichment Determination in Uranium Hexafluoride

In response to needs identified by the International Atomic Energy Agency (IAEA) research is underway to develop In-Field Alpha Spectrometry (IFAS) as a method to allow IAEA safeguards inspectors to collect samples of uranium hexafluoride (UF6) at processing facilities to assess and verify uranium enrichment. For sample collection, the IFAS method uses Single-Use Destructive Assay (SUDA) samplers, which contain thin zeolite coatings that trap UF6 gas and convert it to the safer, more stable form uranyl fluoride (UO2F2). For alpha spectrometry, the IFAS instrument employs a large area silicon semiconductor transducer to detect and record alpha particle energy-deposition events. Over the past year optimization work has significantly increased the diameter of useful SUDA samples (from 12.7 mm to 48 mm), improved the manufacturability and reproducibility of SUDA samples, increased the area of the IFAS alpha spectrometer sensor from 1.2 cm to 3.1 cm, and improved source positioning within the IFAS. This paper will report on this optimization work, its impacts on IFAS performance, and future plans for IFAS miniaturization, improvements, and testing.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗

In-Field Alpha Spectrometry to Assess Uranium Enrichment In Uranium Hexafluoride

A new In-Field Alpha Spectrometry (IFAS) system is being developed to allow quick turnaround measurements of uranium enrichment in uranium hexafluoride samples. Samples are collected using specially-designed Single-Use Destructive Assay (SUDA) wafers which have an absorptive thin film of zeolite deposited onto a quartz substrate. The SUDA samples, along with a special holder, are designed to be attached directly to a sampling tap at a gas centrifuge enrichment plant or a uranium conversion facility, allowing gaseous UF6 to come into direct contact with the zeolite. The zeolite absorbs this material and converts it into stable, safe UO2F2 within a few minutes. Once the sample has been collected it is transferred to the IFAS system where a solid-state, silicon alpha spectrometer is used to quantitatively measure the alpha emissions from 234U, 235U, and 238U form the sample. The SUDA samples are designed so that thin-film spectra are produced, and the SUDA samples and IFAS system are designed so that a complete measurement, with a final 235U:Utotal determination of <±2%, can be made in less than eight hours. This short time frame will allow an inspector to get results on-site within one working shift.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗

Select Proliferation Studies on TRISO-fueled, Heat-Pipe-cooled Microreactors

Nuclear microreactors carry the potential to open up new markets for the nuclear industry, as their expected cost competitiveness in non-traditional market segments (e.g., mines, military bases, extraterrestrial surfaces, and remote areas), and their inherent safety features make them deployable when other power sources are unavailable or difficult to exploit. For countries that have not traditionally participated in nuclear power, microreactors represent a clean energy solution [1]. However, their use, especially in non-weapons states, may entail challenges in terms of maintaining international nuclear safeguards [2]. Furthermore, the deployment locations where microreactors may prove most cost competitive would be difficult to access by state and International Atomic Energy Agency (IAEA) inspectors [3]. In addition to the isolated nature of potential deployment sites, the low-power characteristic of microreactors suggests that numerous microreactors would need to be deployed to meet energy demands. That, coupled with the unique physics of many current microreactor designs, opens up a new area of research with respect to nonproliferation and safeguards concerns [2]. Whereas traditional facilities are inspected as isolated cases when looking for signs of diversion or misuse; microreactors may need to be assessed in the context of the entire fleet to which they belong. International safeguards necessitate timely detection of any significant quantities (SQs) of material that are being diverted (e.g., 1 SQ of special nuclear material diverted over the course of a 1-year period) [4]. For low-enriched uranium, the IAEA defines 1 SQ as corresponding to 75 kg of 235U. The purpose of the present paper is to explore the detectability threshold for material diversion in microreactors by relying on critical control drum angles, excess reactivity, and the reactor lifetime as the selected operational parameters. For this assessment, a heat-pipe-cooled microreactor was regarded as the base design. While the conclusions reached in this paper are not readily extendable to the design of actual microreactors, the analysis herein enables conclusions to be drawn regarding the level of accuracy needed for reference calculations in order to detect diversion scenarios by utilizing the selected operational parameters (i.e., mainly control drum angles, critical insertion angle, and the reactor lifetime).

22 - GENERAL STUDIES OF NUCLEAR REACTORS↗

Knowledge Transfer Program for International Nuclear Safeguards

Nuclear safeguards were first announced in 1945 by the U.S., Canadian and British governments as a means to exchange scientific information about peaceful uses of atomic energy and prevent the use of nuclear material for weapons. International nuclear safeguards, now under the provision of the International Atomic Energy Agency (IAEA), serves to hold accountable the 140 member countries (States) that have entered into treaties and agreements against the spread of nuclear weapons. Most notably, the IAEA acts as a nuclear materials inspectorate under the global Nuclear Non-Proliferation Treaty, brought about in 1968, that specifies commitments member States make to the world?s non-proliferation regime. The Office of International Nuclear Safeguards (OINS) is part of the National Nuclear Security Administration, a semi-autonomous agency within the U.S. Department of Energy. Within OINS, the Human Capital Development program recognizes the need to build workforce capacity and safeguards expertise. This includes supporting the education and training of younger generations working in international nuclear safeguards. One of the program?s main concerns is core competencies being lost to retirement or attrition and building knowledge retention pipelines from senior to new professionals. One identified core competency is knowledge gained by individuals who have completed IAEA assignments such as missions to member States to conduct safeguards inspections. Such individuals possess unique knowledge, and efforts are being put forth to effectively capture this knowledge within the national laboratories complex. To this end, we report findings from a one-year mentor-mentee knowledge retention program in which an international safeguards subject matter expert imparted knowledge and skills to a willing professional mentee. The knowledge and skills stem from the mentor?s multi-year assignment at the IAEA in Vienna, Austria.

98 - NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL↗

An international study on THM modelling of the full-scale heater experiment at Mont Terri laboratory

We present results from an international model comparison study of the Full-Scale Emplacement (FE) experiment in Opalinus Clay at the Mont Terri Laboratory, Switzerland. Based on a provided parameter set the teams decided which parameters they adopted for their models, whether they considered the excavation and the ventilation phase in addition to the heating phase and if they included technical features like the shotcrete or the EDZ. The teams were able to reproduce the measured parameters temperature, relative humidity and pore pressure. The modelled results for temperature agree very closely between the teams especially in the sensors in Opalinus Clay. All teams were able to reproduce the redistribution of water in the bentonite backfill due to heating. The evolution of the relative humidity showed similar trends with differences in the intensity of the dry out effect. To model the pore pressure evolution is more complex because it comprises the full interaction of the coupled THM processes. The spread between the pore pressure modelled by the teams was larger, with some teams overestimating the pressure increase due to heating and some teams overestimating the extent of drainage. The agreement of modelled results with measurements improves with larger distance to the heater. We conclude that the EDZ and the shotcrete potentially influence the behaviour of the rock causing higher differences closer to the heater. Further research is needed to better implement those influences into the models. Based on the calibrated models, the future evolution of temperature, relative humidity and pore pressure was predicted over the next 10 years following a change of the heat power applied in 2023 and 2024. Again, the predicted temperatures agree very closely between the teams. Most teams do not expect an increase in relative humidity during the next 10 years after the initial dry-out.

58 GEOSCIENCES↗

Idaho Explosive Detection System

Learn how INL researchers are making the world safer by developing an explosives detection system that can inspect cargo. For more information about INL security research, visit http://www.facebook.com/idahonationallaboratory

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗