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At least 289 records · Page 16

Waste Attributes of SMRs Scheduled for Near Term Deployment

This is a short presentation as part of a "roundtable" panel on Back-end Fuel Cycle Implications of Advanced Reactor Fuel Cycles. It covers an evaluation of waste generation rates projected for small modular reactors expected to be constructed this decade which are compared to a reference gigawatt-scale light water reactor like those in the current commercial fleet. For ease of comparison, results are normalized per unit of electricity generated.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

The Effects of Reflector on Core Reactivity for Conceptual Soluble Boron Free SMR

Various small modular reactor (SMR) designs have been proposed by the nuclear vendors and universities in order to address the energy needs for developing countries and remote communities. Most of them target for the long-term fuel cycle of 4 years or more to achieve high availability. In addition, soluble boron free operation is proposed to simplify the primary system, to enhance the safety characteristics by inherent negative moderator temperature coefficients, etc. The neutron economy should be improved to achieve longer cycle length with a small core. Therefore, analysis of reflector for Conceptual Soluble Boron Free SMR. (CSBF-SMR) is required. In this study, five materials for radial reflector were selected to investigate the effect on core reactivity. Their thickness was also analyzed to get an optimum configuration. The goal of this study is to determine optimum material and thickness of reflector of the CSBF-SMR.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Modeling and simulation of earthquake soil structure interaction excited by inclined seismic waves

Presented is an application of wave potential formulation (WPF) together with domain reduction method (DRM) to modeling earthquake soil structure interaction (ESSI) behavior in horizontally layered ground under inclined incident seismic waves. Wave potential formulation is used to develop a spatially varying, inclined seismic wave field from incident Primary (P) and Secondary (S) waves that propagate through layered ground. Developed seismic wave field is then used to develop effective forces for Domain Reduction Method that are then used for analyzing ESSI response of a soil structure system. Developed methodology, called WPF-DRM, is verified using analytic solution for a free field response of layered ground subjected to inclined incident waves. Developed WPF-DRM methodology is illustrated through analysis of an ESSI response of a deeply embedded structure, a small modular reactor (SMR) subjected to incident S wave polarized in vertical plane (SV) with variation in inclinations and frequencies. Presented example highlights the influences of incident wave inclination and frequency on ESSI response of analyzed SMR.

58 GEOSCIENCES↗

Building a Decommissioning Army - 19259

It is safe to say that Canada has, for the greater part, seen the end of large-scale commercial nuclear new build projects. In spite of a renaissance in the last decade, and the fact that nuclear is now widely viewed by many as the original green energy, refurbishment projects both underway and scheduled will likely be the last of the megaprojects. In a sense, the future of large-scale nuclear power generation is the end of large scale nuclear power generation. Just as the construction and operation of these facilities has, for decades, employed scores of highly skilled workers, so too will the decommissioning process. Today, Canadian decommissioning activities are first-of-kind (FOAK)projects. There are very few experts in the field and certainly no plan in place to educate and prepare the numbers of workers we will need to safely and successfully execute the programs. It is to this end that I propose a national education centre be created to recruit, educate and mobilize all manner of professionals needed to meet this challenge. In an effort to meet the human and technological needs of the industry in the future, I propose the development of a Canadian Institute where the students study and learn how to decommission a nuclear power plant. The student body of the institute would comprise graduate students with backgrounds in a wide variety of studies such as engineering, physics, chemistry, commerce, environmental studies, and communications. Collectively, their time spent at the institute shall not only prepare them for a career in nuclear but will also vastly improve the technical readiness level of the Canadian nuclear industry to transition from large-scale nuclear utilities to a future of small modular reactors (SMRs) and renewable energy resources. Staff at the institute would be selected from leaders in the industry -those who have shown a passion for nuclear and have demonstrated innovative problem solving and leadership. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Open Architecture for Cost Savings in Advanced Nuclear Reactors

Recently, nuclear power plant build projects in the West have run over budget due to high capital costs and schedule overruns. Compared to other sources of energy, nuclear power plants have higher capital costs. Reactors are often different at every site, resulting in a lack of standardization. Nuclear is expected to compete with other low carbon sources of energy which have lower capital costs making it essential for nuclear to develop ways of reducing costs. Strategies such as standardization, learning rates, modularization, and schedule reduction in advanced reactors can reduce nuclear costs by about 40%. Standardization as a way of cutting capital costs has been explored even in large nuclear power plants. Standardization of certain plant components can result in lower component and installation costs and higher learning from experience. Standardization can be achieved by adopting a criterion of key performance indicators and general design principles for a specific system or component such as the balance of plant. Modularization allows the construction of certain components of SMRs in a factory, which saves time, increases productivity, and encourages higher learning rates. Production learning decreases the time and the cost related to an activity. The potential for modularized components of advanced reactors to be manufactured in factories makes it conducive to achieving higher learning rates. Developing large-capacity nuclear programs through sequential builds cultivates a higher learning rate, which in effect may reduce schedule overruns. Open architecture has been identified as a way to drive standardization among advanced reactor designs and result in cost savings. Open architecture (OA) is defined as a design enabling a diverse supply chain by defining and publishing requirements of systems or equipment in functional and/or interface terms, utilizing technical standards in widespread use. Currently, the nuclear industry’s approach is to use closed architecture, making most designs proprietary. However, collaboration between various advanced reactor vendors and suppliers utilizing the concept of open architecture can result in modular and standardized architecture of subsystems or subcomponents of a nuclear power plant. Completely standardizing nuclear power plants may be impossible, however, certain common subsystems amongst the various reactor designs could be standardized and/or access a wider supply chain and leverage existing learning from other sectors. Open architecture will save time and allocate resources to the parts of the plants that have the most unique features. A key advantage of open architecture is its ability to improve production learning across advanced reactors (AR) types in the industry, by providing and utilizing the same kind of component. Sodium fast reactor (SFR), High Temperature Gas Reactor (HTGR) and Molten Salt Reactor (MSR) are the advanced reactors considered for this project. This paper aims to determine the cost savings in advanced reactor programs due to open architecture learning rate. This work is an extension of work done on light water reactor small modular reactors; the cost methodology was utilized to investigate the impact of open architecture on advanced reactors with a particular focus on sodium fast reactors. The cost data on sodium fast reactors used in the model presented the most adequate information required for the analysis.

Advanced Nuclear Reactors↗

Power Distribution Control Strategy of a Conceptual Soluble Boron Free SMR

In a commercial PWR, the two primary functions of control rods are to provide rapid shutdown and to control power distribution, whereas the initial excess reactivity associated with fuel loading is controlled by the soluble boron in the coolant and burnable absorbers. The required number of total control rods is determined by the shutdown margin of the reactor. The control rod grouping is also required to control power distribution. Therefore, removal of soluble boron requires extra reliance on the control rods to compensate excess reactivity. In a soluble boron free reactor which has highly negative MTC requires an increase in both worth and number of control rod assemblies to ensure adequate shutdown margin. In addition, since control rods are partially inserted into the reactor core, their presence adversely affects the power distribution and thus may make high peaking factors leading to an operating margin reduction. In this paper, the strategy of control rods operation to control excess reactivity and power distribution have been studied. Also, shutdown capability of the control rods was examined. A loading pattern for a Conceptual Soluble Boron Free Small Modular Reactor (CSBF-SMR) has been constructed. Two groups of regulating banks employ Ag-In-Cd to control excess reactivity and power distributions during the cycle operation and 1 group of shutdown bank made of B{sub 4}C were used.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

SMR Accelerated Development Needs with Adequate Safety

The development of advanced Small Modular Reactors (SMRs) is ongoing. A customer-focused development approach requires accelerated design and analysis of the reactor system while minimizing engineering, regulatory, and economic challenges. SMRs, although not a new concept, are being considered for rapid deployment with optimized economic scalability, and several designs are currently seeking approval. Understanding the research and development needs, with adequate safety support, accelerates reactor development.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Design and analysis of embedded I and C for loop-scale magnetically suspended pump - 261

Improving nuclear reactor designs and fuel processing technologies for safer and more efficient operation require the development of new component designs. In particular, many of the advanced reactor design such as the molten salt reactors and high-temperature gas cooled reactors have operating environments beyond the ability of many currently commercially available components. To address this, new cross-cutting technologies need to be developed that will enable the design, fabrication, and reliable operation of new classes of reactor components. The Advanced Sensor Initiative of the Nuclear Energy Enabling Technologies initiative is investigating advanced sensor and control designs that are capable of operating in these extreme environments. Under this initiative Oak Ridge National Laboratory (ORNL) has been developing embedded instrumentation and control for extreme environments. To develop, test, and validate these new sensing and control techniques, ORNL is building a pump testbed with submerged magnetic bearings. The eventual goal is to apply these techniques to a high temperature (700 deg. C) canned rotor pump that utilizes active magnetic bearings to eliminate the need for mechanical bearings and seals. The technologies will benefit the Next Generation Power Plant, Advanced Reactor Concepts, and Small Modular Reactor programs. In this paper we will detail the design and analysis of the embedded I and C testbed with submerged magnetic bearings. Then we will analyze the fluid forces on the shaft. Finally, we will develop the radial and thrust bearing geometries needed to meet the force requirements. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Advanced Nuclear Technology: Integrated Pressurized Water Reactor (iPWR) Containment Aerosol Deposition Behavior

Under assumed severe accident conditions, a nuclear reactor’s containment vessel provides a defense-in-depth function by preventing radionuclide particle release. This is achieved by creating a physical barrier and by decontamination (removal of aerosolized particles produced during the accident). Decontamination occurs through active mechanical systems (where applicable) and passive natural occurring phenomena. Due to their comparatively higher containment surface area to volume ratios when compared to large light water reactors (LWRs), the integrated pressurized water reactor (iPWR) subcategory of small modular reactors (SMRs) has design features that increase the significance of the passive decontamination factors, due to the following natural occurring phenomena: gravitational settling, thermophoresis, diffusiophoresis, and impaction due to convective flows. The purpose of this study is to provide estimates for the decontamination associated with these phenomena. Specifically, these results provide decontamination factors associated with the thermal-hydraulic and geometric parameters that characterize iPWRs, based on the experimental work documented in this report.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Design and Operation of an Electric Peaking/Industrial Steam Production Unit for SMRs

Various methods of Thermal Energy Storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid variability caused by daily load demand changes and renewable intermittency. Our previous research has shown that coupling a sensible heat TES system to a Small Modular Reactor (SMR) allows the reactor to run at effectively nominal full power during periods of variable electric demand by bypassing steam to the TES system during periods of excess capacity. In this paper we demonstrate that this stored thermal energy can be recovered; allowing the TES system to act as a peaking unit during periods of high electric demand, or used to produce steam for ancillary applications such as desalination. For both applications the reactor can operate continuously at approximately 100% power.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Intern Poster Session

This poster has been developed for display during the 2023 Intern Poster Session. The poster is apart of the Nuclear Research and Experiments category. The focus of this poster is on the modifications made to the design of an integral effect test (IET) facility currently being designed for a new Small Modular Reactor (SMR) design. My contributions made to the IET facility are laid out along with an explanation on some of the aspects of designing a new nuclear reactor. This poster covers the ideas and importance of scaling and IET facilities with the context of the standards set by the NRC. There are also graphics of some other examples of IET facilities developed for other reactor designs. My contributions include designing the piping and instrumentation layout of the IET facility using CAD software. This is a key step in the process of designing this IET facility and needs to be designed to avoid excessive head loss.

42 ENGINEERING↗

A Scaling-based Applicability Assessment of the CAER Integrated Systems Test Facility

This paper presents a scaling-based applicability assessment of the Integrated Systems Test (IST) facility located at the Center of Advanced Engineering Research in Forest, Virginia. The assessment draws upon both traditional and contemporary scaling methods, seeking an optimal representation of light water reactor (LWR) and small modular reactor (SMR) characteristics during design-basis events. Based on published LWR loss-of-coolant-accident phenomena identification and ranking tables compiled with a similar assessment completed by BWXT mPower, Inc., for the mPower{sup TM} SMR, the phenomena considered in the IST design include break flow, decay heat, loop thermal-hydraulics, and primary-to-secondary heat transfer. Among these, the single- and two-phase natural circulation and system depressurization, by association to loop thermal-hydraulics, were the principal challenges. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Simulation of Boiling Flow in a Helical Coil Using a Homogeneous Equilibrium Model with the Nek-2P CFD Code

Recent developments in the field of nuclear energy have lead to an increased interest in the design of helically coiled steam generators. In particular, their compact size, and high heat transfer rates make them ideal for small modular reactors. This has lead to a renewed effort to investigate the characteristics of fluid flow and heat transfer in and around helical coils both numerically and experimentally. The focus of this work is on the development of a consistent modeling, formulation, and simulation framework for boiling flows in helical coils using the highly scalable Nek-2P CFD code. As a first step, two phase flow is accounted for using a homogeneous equilibrium model. Results for both single and multiphase flows are compared to results obtained from Star-CCM+. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Securing Future Energy Supplies: From Renewables to Microreactors

This session will provide insight into how future energy deployments, critical to national-level programs focused on reducing carbon emissions, can be secured-by-design using lessons learned from current energy infrastructure. It will begin with an overview of current threats and risks associated with renewable energy assets and systems, primarily wind and solar, focusing on their control architecture and key system functions for both efficient and safe operations. This talk will then translate the key takeaways from current renewable infrastructure into applications for securing future energy systems, including microreactors and small modular reactors (SMRs), based on planned concepts of operations and control. Microreactors and SMRs are intended to be factory-assembled with commercially available components and deployed in more remote or distributed environments, necessitating centralized control centers, remote monitoring, and offsite maintenance and technical support. All of these factors lead these assets to a security posture and controls more similar to today's renewable energy assets than today's nuclear reactors, which represents a significant shift in mindset for the nuclear industry. This talk will provide justification for this shift as well as a path forward to motivate securing these groundbreaking technologies from the outset of their design and deployment.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DEVELOPMENT OF OPERATIONAL CONCEPTS FOR ADVANCED SMRs: THE ROLE OF COGNITIVE SYSTEMS ENGINEERING

Advanced small modular reactors (AdvSMRs) will use advanced digital instrumentation and control systems, and make greater use of automation. These advances not only pose technical and operational challenges, but will inevitably have an effect on the operating and maintenance (O&M) cost of new plants. However, there is much uncertainty about the impact of AdvSMR designs on operational and human factors considerations, such as workload, situation awareness, human reliability, staffing levels, and the appropriate allocation of functions between the crew and various automated plant systems. Existing human factors and systems engineering design standards and methodologies are not current in terms of human interaction requirements for dynamic automated systems and are no longer suitable for the analysis of evolving operational concepts. New models and guidance for operational concepts for complex socio-technical systems need to adopt a state-of-the-art approach such as Cognitive Systems Engineering (CSE) that gives due consideration to the role of personnel. This approach we report on helps to identify and evaluate human challenges related to non-traditional concepts of operations. A framework - defining operational strategies was developed based on the operational analysis of Argonne National Laboratory’s Experimental Breeder Reactor-II (EBR-II), a small (20MWe) sodium-cooled reactor that was successfully operated for thirty years. Insights from the application of the systematic application of the methodology and its utility are reviewed and arguments for the formal adoption of CSE as a value-added part of the Systems Engineering process are presented.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Draft Function Allocation Framework and Preliminary Technical Basis for Advanced SMR Concepts of Operations

This report presents preliminary research results from the investigation into the development of new models and guidance for Concepts of Operations in advanced small modular reactor (AdvSMR) designs. AdvSMRs are nuclear power plants (NPPs), but unlike conventional large NPPs that are constructed on site, AdvSMRs systems and components will be fabricated in a factory and then assembled on site. AdvSMRs will also use advanced digital instrumentation and control systems, and make greater use of automation. Some AdvSMR designs also propose to be operated in a multi-unit configuration with a single central control room as a way to be more cost-competitive with existing NPPs. These differences from conventional NPPs not only pose technical and operational challenges, but they will undoubtedly also have regulatory compliance implications, especially with respect to staffing requirements and safety standards.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Analysis of a nuclear hybrid energy system using absorption chillers and stratified chilled-water storage with an mPower reactor - 187

The intermittency of renewable energy technology, such as wind and solar power, puts strain on electric grids, often forcing carbon-based and nuclear sources of energy to operate in a load follow mode. Operating nuclear reactors in a load-follow fashion is undesirable due to the associated thermal and mechanical stresses placed on the fuel and reactor components. Various methods of Thermal Energy Storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid instabilities caused by daily load demand changes and renewable intermittency. This is known as a Nuclear Hybrid Energy System (NHES). Previous research has found that a stratified chilled-water storage tank can help displace peak cooling loads to off-peak hours. In this study, a dynamic single effect, lithium bromide absorption chiller model was developed as a callable FORTRAN subroutine. Cooling towers, a stratified chilled-water storage tank, and cooling loads characteristic of a large campus were included to form a comprehensive TES model. This TES model was coupled to a high-fidelity mPower sized Small Modular Reactor (SMR) FORTRAN code that provides the transient behavior of primary and secondary-side components. Control algorithms based on excess capacity and conditions in the stratified chilled-water storage tank were used to determine when to divert low-pressure steam from the turbines to the absorption chillers in order to keep reactor power near steady-state. Simulation results depict how the TES system and SMR interact, and demonstrate that stratified chilled-water storage is a viable TES technology for an SMR in a NHES. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

The research challenges in security and safeguards for nuclear fission batteries

This paper discusses the nuclear security and safeguards research challenges presented by the development and deployment of nuclear fission batteries. These are defined as easily transportable and deployable nuclear systems which are designed to operate either unattended or autonomously. We start by defining the current landscape of domestic and international safeguards and security and discuss how it can be affected by the introduction these new nuclear systems. We then specifically discuss the technology gaps and technologies to be developed to facilitate their practical deployment. We find that, as expected, we can leverage conclusions from existing security and safeguards studies for small modular rectors and develop bespoke target set analyses to inform security postures based on probabilistic risk assessment. We find also that specific fission battery security economic analysis tools are needed and security by design must be applied early. However, the most important finding is that these new systems will require a new comprehensive set of cyber tools covering transportation, installation, operation, maintenance security of the fission battery systems. Altogether, we find that the development of the necessary security and safeguards requirements at the design phase of such a technology will be of great benefit in the smooth deployment of this modern nuclear energy system.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗