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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

The Criticality Safety Studies of Joonhong Ahn

The recent passing of UC Berkeley professor Joonhong Ahn at the age of 57 has been a dear loss to the community of nuclear scientists at large. His contributions to studies on advanced fuel cycle development and the societal and ethical aspects of nuclear technology were known around the world and fostered a great reputation. He produced at least fifty peer-reviewed journal papers, authored or contributed to ten books, and organized a considerable number of international meetings. Ahn's studies led to his eminence in the area of nuclear waste management, where he focused on repository performance assessments along with their impact on society. These assessments included the development of analytical models for nuclide transport phenomena and evaluation of the possibility of criticality events imparting a dose to the biosphere. This paper will summarize his achievements in criticality safety along with developments before his passing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Physical Protection of Spent Fuel Shipments: Resolution of Stakeholder Concerns Through Rulemaking - 12284

In 1999, the State of Nevada brought its concerns about physical protection of current spent nuclear fuel (SNF) shipments, and future SNF shipments to a federal repository, before the NRC in a 1999 petition for rulemaking (PRM-73-10). In October 2010, the NRC published a rulemaking decision which would significantly strengthen physical protection of SNF in transit. The newest articulation of the rule (10 CFR 73.37) incorporates regulatory clarifications and security enhancements requested in Nevada's 1999 petition for rulemaking, codifies the findings of the Nuclear NRC and DOE consequence analyses into policy guidance documents and brings forward into regulations the agency and licensee experience gained since the terrorist attacks of September 11, 2001. Although at present DOE SNF shipments would continue to be exempt from these NRC regulations, Nevada considers the rule to constitute a largely satisfactory resolution to stakeholder concerns raised in the original petition and in subsequent comments submitted to the NRC. This paper reviews the process of regulatory changes, assesses the specific improvements contained in the new rules and briefly describes the significance of the new rule in the context of a future national nuclear waste management program. Nevada's petition for rulemaking led to a generally satisfactory resolution of the State's concerns. The decade plus timeframe from petition to rulemaking conclusion saw a sea change in many aspects of the relevant issues - perhaps most importantly the attacks on 9/11 led to the recognition by regulatory bodies that a new threat environment exists wherein shipments of SNF and HLW pose a viable target for human initiated events. The State of Nevada has always considered security a critical concern for the transport of these highly radioactive materials. This was one of the primary reasons for the original rulemaking petition and subsequent advocacy by Nevada on related issues. NRC decisions on the majority of the concerns expressed in the petition, additional developments by other regulatory bodies and the change in how the United States sees threats to the homeland - all of these produced a satisfactory resolution through the rulemaking process. While not all of the concerns expressed by Nevada were addressed in the proposed rule and significant challenges face any programmatic shipment campaign in the future, the lesson learned on this occasion is that stakeholder concerns can be resolved through rulemaking. If DOE would engage with stakeholders on its role in transport of SNF and HLW under the NWPA, these concerns would be better addressed. Specifically the attempts by DOE to resist transportation and security regulations now considered necessary by the NRC for the adequate protection of the shipments of highly radioactive materials, these DOE efforts seem ill advised. One clear lesson learned from this successful rulemaking petition process is that the system of stakeholder input can work to better the regulatory environment. (authors)

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

Ten-Year Review of US/German Collaboration in Salt Repository Research - 20069

A multinational collaboration on salt repository research, design and operation has enjoyed remarkable success since reinvigorating efforts in 2010. Nations now engaged in the shared salt repository research agenda include Germany, the United States, the United Kingdom, the Netherlands, and Poland. The scientific basis for safe and permanent disposal of nuclear waste in salt formations has been strengthened by annual workshops that recognize and address contemporary research, including breakout sessions to stimulate open discussion and focus planning for ongoing investigations. Collaboration not only identifies pertinent technical issues, but facilitates timely, expert, and cost-effective consideration. Contemporary workshops have been held annually since 2010 and are documented in yearly state-of-the-art Proceedings, which summarize content and conclusions. The Proceedings help preserve scientific understanding and provide timely source references. These workshops often produce valuable joint publications coordinated with the Nuclear Energy Agency and other suitable external forums for dissemination. Nuclear waste management programs face growing challenges, while permanent disposal in salt formations provides a robust, safe option for several nations. Workshop format and publications provide a cost-effective insurance against loss of scientific expertise and institutional memory. This paper summarizes ten US/German workshops since formal reinitiation, reexamines key technical issues, discusses the evolving research agenda, and highlights successes and challenges. (authors)

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

Soft Robotic Glove System for Wearable Haptic Teleoperation - 18373

Managing nuclear waste is a difficult, dangerous, and costly task. Teleoperation of robotic operators is an important functionality for this application, allowing robotic devices to operate in dangerous environments while still leveraging the existing abilities and technical knowledge of human workers. One difficulty in implementing effective teleoperation systems is that human operators rely on more senses beside sight: in particular, touch. The sense of touch could provide significant benefits for teleoperation, preventing environmental mishaps that could cost millions of dollars. To help remedy this problem, we present a soft haptic feedback glove system. The primary functionality of this system is to provide tactile and force feedback on the user's hands. This was achieved using custom cylindrical pneumatic actuators. These actuators consist of plastic sheeting folded into a hollow-walled cylinder which is connected to a pressure source. When pressurized, the cylinder walls expand and the cylinder straightens, with the force being related to the pressure. The glove system has one of these actuators over each of the user's three main fingers (index, middle, and thumb), where pressurizing the actuator applies a reaction force to the finger of the user, mimicking the resistance of a grasped object. The expansion of these actuators also causes them to physically press against the user's fingers, giving them the feeling of contact. To demonstrate the usability of this system, we implemented a virtual environment in V-REP simulating the interactions between a robotic Jaco Arm and a floating ball. This simulation receives hand and figure positions from the haptic glove and used them to drive the state of the simulated Jaco Arm. In response to the interactions between the Jaco and the floating ball, the simulation returns commands to the glove, instructing it to pressurize or depressurize its actuators as appropriate, allowing the user to feel the ball in their hand. We tested users in their ability to prevent the ball from floating away using this system with and without the haptic feedback. Results show that the addition of haptic feedback significantly improved the ability of users to interact precisely with the environment. We also used the finger positions of the haptic glove to control a physical robotic hand, and demonstrated the system's usability for control of real robots, though the lack of sensors on the robot made providing the tactile feedback impractical. However, there is more to grasping and holding an object than just the feeling of contact and the resistance to closing one's hand. The weight of the object will apply forces to the user's other joints as they hold it. To this end, we added a haptic feedback device for the user's wrist, a technique that can be generalized to the user's other joints. This is made up of reverse Pneumatic Artificial Muscles (rPAMs) stretching across the wrist between mounts on the hand and forearm. These rPAM actuators are tubes of silicone wrapped in thread such that they extend when pressurized. This extension can apply torque on the user's wrist, mimicking the feeling of gravity, or allowing the simulation of additional contact forces (such as the user's hand impacting an object). We tested this wrist device independently using a simulated path-following experiment. Users showed a significant improvement in performance when aided by haptic feedback during sinusoidal path experiments, demonstrating the usability of this approach. We then integrated the two systems, further demonstrating the usability of this approach. This project represents the first step towards a more effective robotic teleoperation system, allowing skilled human workers to perform tasks more effectively while remaining out of danger. (authors)

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

Actinide Solubility and Speciation in the WIPP [PowerPoint]

The presentation begins with the role and need for nuclear repositories (overall concept, international updates (Sweden, Finland, France, China), US approach and current status), then moves on to the WIPP TRU repository concept (design, current status--safety incidents of February 5 and 14, 2014, path forward), and finally considers the WIPP safety case: dissolved actinide concentrations (overall approach, oxidation state distribution and redox control, solubility of actinides, colloidal contribution and microbial effects). The following conclusions are set forth: (1) International programs are moving forward, but at a very slow and somewhat sporadic pace. (2) In the United States, the Salt repository concept, from the perspective of the long-term safety case, remains a viable option for nuclear waste management despite the current operational issues/concerns. (3) Current model/PA prediction (WIPP example) are built on redundant conservatisms. These conservatisms are being addressed in the ongoing and future research to fill existing data gaps--redox control of plutonium by Fe(0, II), thorium (analog) solubility studies in simulated brine, contribution of intrinsic and biocolloids to the mobile concentration, and clarification of microbial ecology and effects.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Treatment of irradiated graphite from French Bugey reactor

In 2008, following the general French plan for nuclear waste management, Electricite de France attempted to find for irradiated graphite an alternative solution to direct storage at the low-activity long-life storage center in France managed by the national agency for wastes (ANDRA). EDF management requested that its engineering arm, EDF CIDEN, study the graphite treatment alternatives to direct storage. In mid-2008, this study revealed the potential advantage for EDF to use a steam reforming process known as Thermal Organic Reduction, 'THOR' (owned by Studsvik, Inc., USA), to treat or destroy the graphite matrix and limit the quantity of secondary waste to be stored. In late 2009, EDF began a test program with Studsvik to determine if the THOR steam reforming process could be used to destroy the graphite. The program also sought to determine if the graphite could be treated to release the bulk of activity while minimizing the gasification of the bulk mass of the graphite. In October 2009, tests with non-irradiated graphite were completed and demonstrated destruction of a graphite matrix by the THOR process at satisfactory rates. After gasifying the graphite, focus shifted to the effect of roasting graphite at high temperatures in inert gases with low concentrations of oxidizing gases to preferentially remove volatile radionuclides while minimizing the graphite mass loss to 5%. A radioactive graphite sleeve was imported from France to the US for these tests. Completed in April 2010, 'Phase I' of testing showed that the process removed >99% of H-3 and 46% of C-14 with <6% mass loss. Completed in September 2011, 'Phase II' testing achieved increased removals as high as 80% C-14. During Phase II, it was also discovered that roasting in a reducing atmosphere helped to limit the oxidation of the graphite. Future work seeks to explore the effects of reducing gases to limit the bulk oxidation of graphite. If the graphite could be decontaminated of long-lived radionuclides up to 95% for C-14 while minimizing mass loss to <5%, this would minimize the volume of any secondary waste streams and potentially lower the waste class of the larger bulk of graphite. Alternatively, if up to 95% decontamination of C-14 is achieved, the graphite may be completely gasified which could result in lower disposal. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Machine learning-enabled prediction of chemical durability of A 2 B 2 O 7 pyrochlore and fluorite

Pyrochlore-structure type and its derivative in a general formula A 2 B 2 O 7 (A = rare earth elements and actinides; B = Ti, Sn, Zr, Hf, Pb, Si, etc.) display excellent structural flexibility and rich crystal chemistry as promising nuclear waste form materials capable of immobilizing actinides and fission products. It is essential to understand these materials’ chemical durability and element release of radionuclides in order to evaluate their performance in near-field environment. However, it is a formidable grand technological challenge to experimentally perform durability testing across hundreds of thousands of possibilities resulting from their extreme compositional complexities due to cation substitutions at both A and B-sites. In this work, we demonstrate a machine learning approach to determine the key materials parameters and structural characteristics governing the leaching behaviors from a small set of selected compositions as model systems, enabling a science-based prediction of their chemical durability that can be extended to a wide range of chemical compositions. The combination of four key structural characteristics and materials parameters, including ionic radius size difference , ionic potential difference , electronegativity difference , and lattice parameter , creates features an optimized prediction of the chemical durability. Two machine learning models, linear regression and Kernel ridge regression models, are trained on the randomly-split training dataset derived from the experimentally-determined elemental release rates, and subsequently tested on the testing dataset. The predicted leaching rates from both machine learning models show an excellent agreement with the experimental data, demonstrating the feasibility of rapidly evaluating the material properties of new compositions. These results highlight the immense potential of synergizing informatics through machine learning-based models and well-controlled experiments of selected model systems to accelerate materials design and discovery with optimized compositions and performance of promising materials for effective nuclear waste management.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Structure–property relations of sodium iron phosphate nuclear waste glasses: Effects of iron redox ratio and glass composition

Iron phosphate glasses, known for their exceptional chemical durability and potential applicability in nuclear waste management, have gained significant attention over the years. The structures of these glasses are complicated by the coexistence of Fe 3+ and Fe 2+ , which plays a crucial role in determining their structures and properties. Here, this work uses molecular dynamics simulations to study the structural changes in Na 2 O–Fe 2 O 3 –P 2 O 5 glasses with varying glass composition and Fe 2+ /Fe 3+ redox ratio. It was found that the redox ratio and modifier contents significantly affected the short-range and medium-range orders in the glasses. Significant changes in the local environments around P 5+ and Fe 3+ were observed, as reflected by the bond distances and coordination numbers. Na + cations are found to preferentially associate with Fe 3+ (rather than Fe 2+ ), whereas Fe 2+ has stronger association with P 5+ than Na + , confirming the structural role of Fe 2+ as a glass modifier. The disruptions in P–O–P linkages upon increasing FeO suggest that FeO causes glass depolymerization. These glasses achieved higher connectivity with increasing Fe 3+ / (Fe 3+ + Fe 2+ ) ratios, conerting phosphorous Q 2 to Q 3 units and iron Q 5 units to Q 4 units. The decrease of nonbridging oxygen fractions with increasing Fe 3+ / (Fe 3+ + Fe 2+ ) ratios, through creating P–O–Fe linkages, is the main reason of enhanced network connectivity. Quantitative structure–property relationship analyses with different structural descriptors were used to correlate with measured properties. The analyses provided valuable insights into structure–property relationships, emphasizing the importance of choosing relevant energy parameters and defining glass network connectivity, particularly in F net descriptors. It was found the Fe–O–P linkage density exhibits strong correlations to measured dissolution rates, supporting the importance of these linkages in improving the chemical durability in iron phosphate glasses.

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

Searching for science in the past and present discussion on commingling policy in the US - 15083

Since 1985, the policy in the United States for disposing of nuclear waste has included commingling defense and civilian spent nuclear fuel (SNF) and high-level radioactive waste (HLW) in a mined geologic repository. Commingling policy is under discussion again because of developments over the last several years in the nuclear waste management and disposal program. The authors reviewed the extent to which scientific and technical information was involved in considerations of commingling from the 1950's to the present. Evaluations undertaken by the US Department of Energy (US DOE) in 1985 and April 2014 are compared and the technical issues of health and safety, transportation, and national security are addressed in both evaluations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Hydrogen Recombiner Catalyst Evaluations for Waste Storage

Radiolysis of water in nuclear waste storage generates hydrogen gas that can accumulate within sludge style waste and be rapidly released during agitation events, creating a significant flammability hazard. Engineering controls are therefore required to limit hydrogen concentrations during both quiescent storage and transient disturbances. Catalytic recombination of hydrogen in waste storage offgas is a proven mitigation strategy, maintaining hydrogen levels below flammability limits and managing sudden concentration spikes. Conventional recombiners rely on platinum and/or palladium catalysts, with development efforts focused on extending service life, increasing active surface area, and ensuring safe deployment in radioactive environments. Savannah River National Laboratory (SRNL) is evaluating a newly developed hydrogen recombiner catalyst from Canadian Nuclear Laboratories as a cost-effective and durable alternative for nuclear waste applications. Testing was conducted in SRNL’s Shielded Cells facility, which enables reduced-scale experimental modeling under radiation fields and near-use-case conditions relevant to radioactive waste storage. Catalyst performance was evaluated using a custom offgas characterization system designed for near-zero flow conditions. The experimental apparatus consisted of a gas-tight 2.7 L PTFE vessel equipped with temperature monitoring, gas flow controls, and a variable-speed mixer to simulate sludge agitation. Offgas composition was monitored using a dedicated gas chromatograph with argon carrier gas and a krypton internal standard. Measurements were obtained for an empty vessel, the vessel containing a well characterized radioactive tank waste sample, and the same configuration with the candidate catalyst installed. Results demonstrate that the new catalyst effectively reduced hydrogen concentrations in the offgas within the constraints of the experimental design. In addition to confirming catalytic activity, the testing provided valuable insights into experimental optimization and considerations for future performance evaluations. These findings support the potential scalability of the technology and highlight its applicability to broader nuclear waste management operations, offering improved safety and reduced operational costs through enhanced catalyst durability and lower replacement frequency.

Tener, Zachary P. [Savannah River National Laborat↗
DOE OSTI2019

Panel Session 56: Nuclear Power Plant Waste Management - US LLW Disposal Issues

This panel focused on specific disposal site issues with the disposal site operators. Representatives from each of the operating commercial disposal sites presented an update of their facility, license, and waste acceptance criteria (WAC) followed by a panel discussion in response to audience questions. WM attendees that ship their radioactive waste to one or more of these commercial disposal sites attended this panel session. Presentations proposed include: 1 - US Nuclear Power Plant Waste Management - US LLW Disposal Issues (Joe Weismann, US Ecology (USA)); 2 - Waste Control Specialists Update 2019 (Dan Burns, Waste Control Specialists LLC (USA)); 3 - Barnwell LLRW Disposal Facility (Mark Lewis, EnergySolutions (USA), Benjamin Smith, Chem Nuclear Systems (USA)); 4 - EnergySolutions Clive Treatment and Disposal Facility Update (Bret Rogers, EnergySolutions (USA))

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

Towards a practical Johnson noise thermometer for long-term measurements in harsh environments

The impact of mechanical and chemical changes in conventional sensors such as thermocouples and resistance thermometers can be avoided by instead using temperature sensors based on fundamental thermometry. A prime example of this is Johnson noise thermometry, which is based on measurement of the fluctuations in the voltage of a resistor arising from thermal motion of charge carriers - i.e. the 'Johnson noise'. A Johnson noise thermometer never needs calibration and is insensitive to the condition of the sensor material. It is therefore ideally suited to long-term temperature measurements in harsh environments, such as nuclear reactor coolant circuits, in-pile measurements, nuclear waste management and storage, and severe accident monitoring. There have been a number of previous attempts to develop a Johnson noise thermometer for the nuclear industry, but none have reached commercial exploitation because of technical problems in practical implementation. The main challenge is to extract the tiny Johnson noise signal from ambient electrical noise influences, both from the internal amplification electronics, and from external electrical noise sources. Recent advances in electronics technology and digital signal processing techniques have opened up new possibilities for developing a viable, practical Johnson noise thermometer. We describe a project funded by the UK Technology Strategy Board (now Innovate UK) 'Developing the nuclear supply chain' call, currently underway, to develop a practical Johnson noise thermometer that makes use of innovative electronics for ultralow noise amplification and signal processing. The new electronics technology has the potential to help overcome the problems encountered with previous attempts at constructing a practical Johnson noise thermometer. An outline of the new developments is presented, together with an overview of the current status of the project. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Cleaning Up Nuclear Wastes

Environmental management is a key DOE mission, in large part because decades of nuclear weapons production and nuclear energy research have left behind huge quantities of radioactive waste. Most of the radioactivity in the waste, however, comes from the element cesium, which is just a tiny fraction of the total waste. An alert research chemist at Oak Ridge National Laboratory, Bruce Moyer, recognized that if cesium could be removed, dealing with the wastes would be much easier and safer. Moyer also was aware of a potential solution—fundamental research into organic molecules that can recognize and capture metal atoms like cesium, some of it supported by the Basic Energy Sciences (BES) office of DOE. With BES support, he put together a team that, over a decade, showed the potential of this approach. Subsequent support by DOE’s Environmental Management Office allowed the team to work out the practical details.

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

Summary Report of Summer Work: High Purity Single Crystal Growth & Microstructure of Ferritic-Martensitic Steels

Harnessing the power of the nuclear sciences for national security and to benefit others is one of Los Alamos National Laboratory’s missions. MST-8 focuses on manipulating and studying how the structure, processing, properties, and performance of materials interact at the atomic level under nuclear conditions. Within this group, single crystal scintillators contribute to the safety and reliability of weapons, provide global security safeguards, and build on scientific principles that carry over to medical fields for cancer detection. Improved cladding materials made of ferritic-martensitic alloys support the mission of DOE-NE’s Fuel Cycle Research and Development program to close the nuclear fuel cycle, aiming to solve nuclear waste management challenges and thereby increase the performance and safety of current and future reactors.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Advances in Materials Science for Environmental and Energy Technologies II

The Materials Science and Technology 2012 Conference and Exhibition (MS&T'12) was held October 7-11, 2012, in Pittsburgh, Pennsylvania. One of the major themes of the conference was Environmental and Energy Issues. Papers from five of the symposia held under that theme are invluded in this volume. These symposia included Materials Issues in Nuclear Waste Management for the 21st Century; Green Technologies for Materials Manufacturing and Processing IV; Energy Storage: Materials, Systems and Applications; Energy Conversion-Photovoltaic, Concentraing Solar Power and Thermoelectric; and Materials Development for Nuclear Applications and Extreme Environments.

Matyas, Dr Josef↗
DOE OSTI2020

Problems of Nuclear Technology and Radiation Safety

This work discusses ethical issues arising in the course of the development of nuclear technologies and related issues of radiation safety. Attention is paid to ethical dilemmas and proposed solutions. The author suggests a critical analysis of the relevant discussions, conducted, first of all, in the English-language literature, and muses on the specifics associated with their transfer to the Russian context. This study considers ethical problems arising in context of the depletion of uranium resources and nuclear waste management and including the inevitable risks for the present and future generations, such as inter- and intragenerational justice (Gardiner's problem) and the problem of the identity of future generations (Parfit’s problem); problems of collectivity and individuality in the assessment of permissible radiation doses for workers at nuclear enterprises and the population associated with the need to combine deontological and utilitarian approaches in the practice of radiation protection. The author demonstrates cultural differences in attitudes towards the safety of the current and future generations of the population of countries and regions and the associated ambiguities in the choice of technology for nuclear reactors, long-term disposal or processing of nuclear waste; double standards in ensuring the radiation safety of personnel of nuclear facilities and the population; ethical problems of risk compensation to workers of radiation-hazardous production facilities; issues of gender differences in sensitivity to radiation exposure, gender equality and discrimination in relation to access to the labor market in the nuclear industry. The article elucidates the importance of socio-humanitarian discussion of the ethical problems of nuclear technologies and radiation safety Such debates currently are almost absent in the Russian-language philosophical literature, despite its exceptional importance due to both the level of development of nuclear energy in Russia and the potential risks that these technologies pose to current and future generations of both employees of nuclear facilities and the population of the country, neighboring countries, and the world. The purpose of this article, thus, is to initiate such a discussion.

ethics of science and technology↗
DOE OSTI2022

Activation of lead coolant in Westinghouse lead fast reactor

The Westinghouse Lead-cooled Fast Reactor (LFR) is a medium-sized, passively safe, scalable reactor being developed by Westinghouse in collaboration with domestic and international organizations with the primary goals of reducing front-end capital cost and generating flexible and cost-competitive electricity while satisfying the highest standards in terms of safety and sustainability. An important aspect of new plant design is an assessment of activation level of its components so that an appropriate nuclear waste management plan can be established. As lead coolant is a distinguishing design feature of the LFR, its activation due to irradiation and the implications on establishing an appropriate waste disposal approach are important for engagement of project stakeholders, customers and nuclear safety regulators. This paper provides a brief description of the Westinghouse LFR design, a background on lead activation phenomenology, and then describes the methodology used for lead activation analysis performed with the computer code Serpent 2. It was determined that impurities naturally occurring in lead have the biggest contribution to lead activation. Corrosion and erosion products from the components immersed in lead can also be important contributors to lead activity and their impact can be limited by appropriate selection of materials and operating conditions. Polonium isotopes, resulting from bismuth generated from lead irradiation and its impurities, bring a notable contribution to the inhalation and ingestion doses during the plant operation and in the first years after the plant shutdown. However, it is not by far as important as for lead-bismuth coolant.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2019

Qualitative Decision and Risk Assessment Approaches for Managing Nuclear Materials

Qualitative approaches to performing decision analyses and risk assessments have recently been developed at ORNL with the goal of providing simple tools to help manage complex projects that have a variety of drivers, constraints, or both. Many of the DOE’s nuclear materials management projects involve making “keep-or-dispose” decisions for nuclear materials and then developing projects to manage or dispose of the materials. ORNL uses decision analysis tools to identify and rank options for accomplishing nuclear materials management projects, and risk assessment tools to evaluate the preferred option(s) to identify risks and prioritize mitigation actions to reduce risks during implementation. This paper focuses on application of the decision analysis and risk-based planning tool(s) to guide management of projects during the planning and start-up phases when only preliminary project information is likely to be available. Such an analysis seeks to reduce risks, lower costs, and improve chances of project success. Examples showing the use of the tools in nuclear waste management scenarios are provided.

Jubin, Robert↗