Synthesis of boron carbide reinforced aluminum castings through mechanical stir casting

Nuclear energy is the leading clean energy source in the United States with 99 nuclear power plants generating approximately 20% of the country’s electricity. While the growth of the industry helps to reduce our reliance on fossil fuels, there is also an increase in nuclear waste. The demand for on-site dry cask spent nuclear fuel storage has increased due to complications with the Yucca Mountain Project and diminishing pool capacity. A novel dry cask consisting of an aluminum metal matrix for effective thermal conductivity with boron carbide as a neutron absorbing additive was investigated using gravity sand casting techniques. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and optical microscopy were used to characterize the resultant microstructure, including boron carbide incorporation and heterogeneity. Results indicate vortex and nonvortex mixing in air with boron carbide (1–10 µm diameter) produces large amounts of porosity and insufficient wetting. Use of a larger particle size distribution of boron carbide (20–60 µm diameter) during high speed vortex mixing prior to casting has shown significant dispersion of up to 12 wt% sufficient for neutron shielding with appropriate wall thickness. These results validate the use of gravity sand casting as a means to produce borated aluminum for an effective alternative to fuel storage.

Download Full-text

Approaches to Safety Justification for Loading of VSC-VVER Containers in ZNPP DSFSF

Nuclear and Radiation Safety ◽

10.32918/nrs.2019.4(84).10 ◽

2019 ◽

pp. 82-87

Author(s):

Ya. Kostiushko ◽

O. Dudka ◽

Yu. Kovbasenko ◽

A. Shepitchak

Keyword(s):

Nuclear Fuel ◽

Nuclear Power ◽

Safety Assessment ◽

Power Plants ◽

Spent Nuclear Fuel ◽

Operating Conditions ◽

Spent Fuel ◽

Fuel Assemblies ◽

Fuel Storage ◽

The Government

The introduction of new fuel for nuclear power plants in Ukraine is related to obtaining a relevant license from the regulatory authority for nuclear and radiation safety of Ukraine. The same approach is used for spent nuclear fuel (SNF) management system. The dry spent fuel storage facility (DSFSF) is the first nuclear facility created for intermediate dry storage of SNF in Ukraine. According to the design based on dry ventilated container storage technology by Sierra Nuclear Corporation and Duke Engineering and Services, ventilated storage containers (VSC-VVER) filled with SNF of VVER-1000 are used, which are located on a special open concrete site. Containers VSC-VVER are modernized VSC-24 containers customized for hexagonal VVER-1000 spent fuel assemblies. The storage safety assessment methodology was created and improved directly during the licensing process. In addition, in accordance with the Energy Strategy of Ukraine up to 2035, one of the key task is the further diversification of nuclear fuel suppliers. Within the framework of the Executive Agreement between the Government of Ukraine and the U.S. Government, activities have been underway since 2000 on the introduction of Westinghouse fuel. The purpose of this project is to develop, supply and qualify alternative nuclear fuel compatible with fuel produced in Russia for Ukrainian NPPs. In addition, a supplementary approach to safety analysis report is being developed to justify feasibility of loading new fuel into the DSFSF containers. The stated results should demonstrate the fulfillment of design criteria under normal operating conditions, abnormal conditions and design-basis accidents of DSFSF components. Thus, the paper highlights both the main problems of DSFSF licensing and obtaining permission for placing new fuel types in DSFSF.

Download Full-text

Prevention of Damage to Spent Nuclear Fuel during Handling Operations

Nuclear and Radiation Safety ◽

10.32918/nrs.2020.2(86).08 ◽

2020 ◽

pp. 62-71

Author(s):

M. Sapon ◽

O. Gorbachenko ◽

S. Kondratyev ◽

V. Krytskyy ◽

V. Mayatsky ◽

...

Keyword(s):

Nuclear Fuel ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Power Plants ◽

Spent Nuclear Fuel ◽

Spent Fuel ◽

Long Term Storage ◽

Fuel Storage ◽

Storage Facilities

According to regulatory requirements, when carrying out handling operations with spent nuclear fuel (SNF), prevention of damage to the spent fuel assemblies (SFA) and especially fuel elements shall be ensured. For this purpose, it is necessary to exclude the risk of SFA falling, SFA uncontrolled displacements, prevent mechanical influences on SFA, at which their damage is possible. Special requirements for handling equipment (in particular, cranes) to exclude these dangerous events, the requirements for equipment strength, resistance to external impacts, reliability, equipment design solutions, manufacturing quality are analyzed in this work. The requirements of Ukrainian and U.S. regulatory documents also are considered. The implementation of these requirements is considered on the example of handling equipment, in particular, spent nuclear fuel storage facilities. This issue is important in view of creation of new SNF storage facilities in Ukraine. These facilities include the storage facility (SFSF) for SNF from water moderated power reactors (WWER): a Сentralized SFSF for storing SNF of Rivne, Khmelnitsky and South-Ukraine Nuclear Power Plants (СSFSF), and SFSF for SNF from high-power channel reactors (RBMK): a dry type SFSF at Chornobyl nuclear power plant (ISF-2). After commissioning of these storage facilities, all spent nuclear fuel from Ukrainian nuclear power plants will be placed for long-term “dry” storage. The safety of handling operations with SNF during its preparation for long-term storage is an important factor.

Download Full-text

Utilização da análise probabilística de segurança como metodologia de avaliação e gerenciamento de riscos inerentes a usinas nucleoelétricas / Use of Probabilistic Safety Assessment as methodology for the evaluation and management of risks inherent in nuclear power plants

Revista Internacional de Tecnología, Ciencia y Sociedad ◽

10.37467/gka-revtechno.v6.1559 ◽

2017 ◽

Vol 6 (2) ◽

pp. 62-66

Author(s):

Jônatas Franco Campos da Mata Mata ◽

Amir Zacarias Mesquita Mesquita

Keyword(s):

Best Practices ◽

Nuclear Power ◽

Safety Assessment ◽

Power Plants ◽

Clean Energy ◽

The United States ◽

Probabilistic Safety Assessment ◽

The United Kingdom ◽

Technological Advances ◽

Probabilistic Safety

RESUMENO século XXI trouxe notáveis avanços tecnológicos com relação a fontes de geração de energia elétrica denominadas de sustentáveis. Entretanto, as fontes limpas de energia apresentam desvantagens, como alto custo de implantação e baixa potência gerada, quando comparadas à matriz nucleoelétrica. Em relação à segurança, a tecnologia nucleoelétrica trabalha com metodologias modernas e eficientes, onde se destaca a Avaliação Probabilística de Segurança (APS). O presente trabalho apresenta as principais etapas para a realização da APS, além de evidenciar as melhores práticas, encontradas em países como os Estados Unidos, França, Canadá e Reino Unido em comparação com o Brasil.ABSTRACT The 21st century brought remarkable technological advances in relation to sources of electricity generation called sustainable. However, clean energy sources have disadvantages, such as high implantation costs and low power generated, when compared to the nucleoelectric matrix. Regarding safety, the nucleoelectric technology works with modern and efficient methodologies, in which the Probabilistic Safety Assessment (PSA) stands out. This paper presents the main steps to perform PSA, in addition to showing the best practices found in countries such as the United States, France, Canada and the United Kingdom compared to Brazil.

Download Full-text

The Advancement of Neutron Shielding Materials for the Storage of Spent Nuclear Fuel

Science and Technology of Nuclear Installations ◽

10.1155/2021/5541047 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Xuelong Fu ◽

Zhengbo Ji ◽

Wei Lin ◽

Yunfeng Yu ◽

Tao Wu

Keyword(s):

Nuclear Fuel ◽

Nuclear Power ◽

Power Plants ◽

Spent Nuclear Fuel ◽

Nuclear Industry ◽

Fast Neutrons ◽

Nuclear Facilities ◽

Cross Sectional ◽

Neutron Shielding ◽

Shielding Composites

With the development of nuclear industry, spent nuclear fuel (SNF) generated from nuclear power plants arouses people’s attention as a result of its high radioactivity, and how to guarantee the reliable operation of nuclear facilities and the staff’s safety occupies a crucial position. To avoid the lethal irradiation, a lot of functional neutron shielding composites have been developed to transform fast neutrons into thermal neutrons which can be absorbed with high macroscopic cross-sectional elements. Irradiation characteristics of nuclear industry have promoted the advancement of neutron shielding materials. Here, we review the latest neutron shielding materials for the storage of spent nuclear fuel containing additives such as boron carbide (B4C), boron nitride (BN), boric acid (H3BO3), and colemanite. Different types of neutron shielding materials, including metal matrix alloys, polymer composites, high density concrete, heavy metals, paraffin, and other neutron shielding composites with high macroscopic cross-sectional elements, arediscussed. The elemental composition, density, and thermal and mechanical properties of neutron shielding materials are also summarized and compared.

Download Full-text

A Comparative Evaluation of Licensing Requirements for Dry Storage of Spent Nuclear Fuel in the United States, Germany, Canada and the Russian Federation

12th International Conference on Nuclear Engineering, Volume 2 ◽

10.1115/icone12-49551 ◽

2004 ◽

Author(s):

Edward Wonder ◽

David S. Duncan ◽

Eric A. Howden

Keyword(s):

United States ◽

Nuclear Fuel ◽

Spent Nuclear Fuel ◽

The United States ◽

Approval Process ◽

Spent Fuel ◽

Regulatory Requirements ◽

Fuel Storage ◽

The Russian Federation ◽

The Republic

Technical activities to support licensing of dry spent nuclear fuel storage facilities are complex, with policy and regulatory requirements often being influenced by politics. Moreover, the process is often convoluted, with numerous and diverse stakeholders making the licensing activity a difficult exercise in consensus-reaching. The objective of this evaluation is to present alternatives to assist the Republic of Kazakhstan (RK) in developing a licensing approach for a planned Dry Spent Fuel Storage Facility. Because the RK lacks experience in licensing a facility of this type, there is considerable interest in knowing more about the approval process in other countries so that an effective, non-redundant method of licensing can be established. This evaluation is limited to a comparison of approaches from the United States, Germany, Russia, and Canada. For each country considered, the following areas were addressed: siting; fuel handling and cask loading; dry fuel storage; and transportation of spent fuel. The regulatory requirements for each phase of the process are presented, and a licensing approach that would best serve the RK is recommended.

Download Full-text

Decommissioning in the United States: Past, Present and Future

ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management, Volume 2 ◽

10.1115/icem2009-16318 ◽

2009 ◽

Author(s):

Jas S. Devgun

Keyword(s):

United States ◽

Nuclear Power ◽

Power Plants ◽

Spent Nuclear Fuel ◽

The United States ◽

Lessons Learned ◽

Department Of Energy ◽

Research Reactors ◽

The Past ◽

The U.S

The experience related to decommissioning of nuclear facilities in the United States is very substantial and covers power reactors, research reactors, and many facilities in the Department of Energy complex. The focus of this paper however is on the commercial power plants. With 104 operating reactors, the U.S. fleet of civilian reactors is still the largest in the world. Nuclear power industry in the United States has undergone a dramatic upturn after decades of stalemate. One effect of this nuclear renaissance has been that the plans have changed for several reactors that were initially destined for decommissioning. Instead, the focus now is on relicensing of the reactors and on power uprates. In fact, after the peak period between 1987 and 1998, no additional power reactors have been shutdown. On the contrary, power uprates in the past twenty years have added a cumulative capacity equivalent to five new reactors. Almost all the operating reactors plan to have license extensions, thus postponing the eventual decommissioning. Nevertheless, in addition to the 9 reactors where licenses have been terminated following decommissioning, 12 power and early demonstration reactors and 14 test & research reactors are permanently shutdown and are in decommissioning phase. Substantial experience and lessons learned are available from the U.S. projects that are of value to the international decommissioning projects, especially where such projects are in early stages. These lessons cover a wide array of areas from decommissioning plans, technology applications, large component removal, regulatory and public interface, decommissioning funding and costs, clean up criteria, surveys of the decommissioned site, and license termination. Additionally, because of the unavailability of a national spent fuel disposition facility, most decommissioning sites are constructing above ground interim storage facilities for the spent nuclear fuel. The U.S. nuclear power projects are also gearing up for the design and licensing of new reactors. Lessons from the past are useful in the development of such designs so that along with the other factors, the designs are optimized for eventual decommissioning as well. This paper provides an overview of the past reactor decommissioning, lessons learned from the past experience, and status of the current decommissioning activities and issues. It also presents some long term projections for the future of decommissioning in the United States.

Download Full-text

Synthesis and reactivity of actinide phosphorano-stabilized carbene and phosphido complexes

10.32469/10355/66123 ◽

2018 ◽

Author(s):

◽

Pokpong Rungthanaphatsophon

Keyword(s):

Nuclear Power ◽

Power Plants ◽

Spent Nuclear Fuel ◽

Visible Region ◽

The United States ◽

Metal Center ◽

Organic Azide ◽

Phosphine Complexes ◽

Carbon Bonds ◽

Electron Reduction

Nuclear power plants have been operated in the United States for over 60 years, generating over 800 terawatt-hours of energy per year. However, there is still no reliable process to recycle the spent nuclear fuel. This dissertation looks at the formation of actinide-ligand multiple bonds, which may give us insights into how to improve the process of separation of actinides from the spent nuclear fuels contaminated with lanthanides. This is because lanthanides cannot participate in multiple bonding and a difference in coordination chemistry between actinides and lanthanides is important in separation methods. This dissertation contains two parts, both of which involve using phosphorus to create new actinide complexes. Chapters 1 and 2 outline the use of phosphorano-stabilized carbene complexes to make short actinide-carbon bonds. In fact, these complexes exhibit the shortest uranium and thorium-carbon bonds reported in the literature. Chapter 3 revolves around investigating the synthesis, characterization, and reactivity of actinide phosphido (monoanionic phosphine) complexes. In this regard, I have synthesized the first trivalent uranium phosphido complex, (C5Me5)2U[P(SiMe3)(2,4,6- Me3C6H2)](THF). The investigation of its reactivity revealed that the complex is capable of 4-electron reduction chemistry. For example, the reaction of (C5Me5)2U[P(SiMe3)(2,4,6-Me3C6H2)](THF) with azidotrimethylsilane, N3SiMe3, produces a U(VI) complex. Three electrons are from the metal center, U(III) to U(VI), and one electron is from reductive coupling of the phosphido ligand. The phosphido chemistry can also be extended to tetravalent uranium and thorium. Chapter 4 outlines the synthesis of thorium phosphido complexes which exhibit an unusual absorption in the visible region which we contributed to a ligand to metal charge transfer. Just by varying the ligand design, we were able to manipulate the HOMO/LUMO gap, which results in an absorption in a different part of the visible region. Appendix A summaries the synthesis of copper(I) complexes with bulky terphenyl ligands. The steric properties of the complex center can be tuned by changing the substituent on the terphenyl. By carefully controlling the steric properties, different coordinating environments around the metal center can be achieved. Finally, Appendix B describes the reactivity of U(IV) phosphido complexes with organic azide and tert-butyl isocyanide.

Download Full-text

The Federal Government’s Role in Enabling the Nuclear Renaissance and a Low-Carbon Energy Future

Volume 10: Emerging Technologies and Topics; Public Policy ◽

10.1115/imece2012-89997 ◽

2012 ◽

Author(s):

John Hanson

Keyword(s):

United States ◽

Interest Rates ◽

Nuclear Power ◽

Power Plants ◽

Nuclear Energy ◽

Clean Energy ◽

The United States ◽

Government Support ◽

Low Carbon ◽

Loan Guarantees

The electric power industry in the United States will face a number of great challenges in the next two decades, including increasing electricity demand and the aging of the current fleet of power plants. These challenges present a major test for the industry, which must invest between $1.5 trillion and $2 trillion by 2030 to meet the increased demand. In addition to these challenges, the potential for climate legislation, controversy over hydraulic fracturing, and post-Fukushima safety concerns have all resulted in significant uncertainty regarding the economics of all major sources of base-load electricity. Currently nuclear power produces 22% of the nation’s electricity, and over 70% of the nation’s low-carbon electricity, even though unfavorable economic conditions have stalled construction of new reactors for over 30 years. The economics are changing, however, as evidenced by the recent construction and operating licenses (COLs) awarded by the Nuclear Regulatory Commission to Southern Company and SCANA Corporation to build two new units each. The successful construction of these units could lead to more favorable financing for future plants. This improved financing, especially if combined with appropriate additional government support, could provide serious momentum for the resurgence of nuclear power in the United States. The most important way in which government support could benefit nuclear power is by increasing the amount of loan guarantees provided to the first wave of new nuclear power plants. This will help encourage additional new builds, which will help reduce the financing risk premium for new nuclear and improve interest rates for future plants. Instead of simply increasing loan guarantees for nuclear energy, a permanent federal financing structure should be established to provide loan guarantees for “clean energy” technologies in general, a category in which nuclear energy should be included. Most importantly, any changes should be made as part of a coherent, long-term energy policy, which would provide utilities with the correct tools to make the necessary investments, and the confidence that will allow them to undertake large-scale projects.

Download Full-text