Disposal Of Nuclear Fuel Research Articles

Technical, Regulatory, and Policy Feasibility Assessments of Rod Consolidation in Spent Nuclear Fuel Disposal

Various approaches have been proposed to address the challenges associated with storage and disposal of spent nuclear fuel. Rod consolidation, which involves extracting only the fuel rods from fuel assemblies and combining them for storage with reduced spacing, gained attention until the 1990s for its benefits in storage efficiency. In this case study, experts from diverse backgrounds evaluate the technical and political feasibility of rod consolidation for enhancing disposal practices. This study conducts a technical and regulatory analysis of rod consolidation under disposal conditions and evaluates its feasibility from a disposal perspective. From a technical viewpoint of 2:1 and 1.5:1 rod consolidations, the rod consolidation methods demonstrate positive effects on nuclear criticality compared to the reference, non-rod consolidation case. For the advanced repository design with elevated temperature conditions of 150 °C or higher, the applicability of rod consolidation becomes more convincing, thereby achieving a reduction in the number of required disposal canisters. In addition, regulatory considerations primarily focus on the requirements for applying rod consolidation technology under the Korea Nuclear Act. Moreover, this research conducts environmental, economic, and acceptance analyses to ascertain the viability of rod consolidation. The findings provide compelling evidence supporting the feasibility of rod consolidation technology for disposal purposes, highlighting its technical, regulatory, economic, environmental, and societal acceptance advantages. However, challenges remain, particularly concerning its applicability to high-burnup nuclear fuel and unresolved regulatory and technical issues.

Preliminary Selection of Safety-Relevant Radionuclides for Long-Term Safety Assessment of Deep Geological Disposal of Spent Nuclear Fuel in South Korea

Preliminary Selection of Safety-Relevant Radionuclides for Long-Term Safety Assessment of Deep Geological Disposal of Spent Nuclear Fuel in South Korea

Review on the Measurement of Thermal Properties of Rocks for Deep Geological Disposal of Spent Nuclear Fuel

Review on the Measurement of Thermal Properties of Rocks for Deep Geological Disposal of Spent Nuclear Fuel

Sensitivity study of risk to future generations from geological disposal of radioactive waste in high strength rock in the UAE

The United Arab Emirates (UAE) Government's Policy is to institute a safe and permanent geological disposal facility (GDF) for the final disposal of higher activity radioactive wastes (HAW). The UAE has yet to identify or decide on a disposal site, and geological data specific to the characterisation of a GDF host rock either lacks sufficient details or is not available in the public domain. However, initial screenings of geological environments in the UAE give an indication of potential suitable host rock formations. This paper presents the results of a study into the factors that influence the risk to future generations from the disposal of Spent Nuclear Fuel (SNF) in a deep underground geological disposal facility. For the purpose of this study the GDF was assumed to be in a High Strength Rock (HSR) geological environment in the Khor Fakkan (KF) Block. GoldSim's Contaminant Transport code was used to model the potential dispersion of radioactivity from a GDF. which enabled the calculation of risk to future generations. The GDF radiological source term was based on the UAE's forecasted SNF inventory. The model created from GoldSim emphasizes the transport of radionuclides through the GDF's engineered barrier systems (EBS), through the surrounding geosphere and into the biosphere. Once in the biosphere the radiation dose to the reference receptor is determined via ingestion from well drinking water, or inhalation through atmospheric dispersion. The paper explores the factors that influence the assessment of risk to people both now and in the future. The analyses presented in this paper are not meant to be used in site selection decision making or in the assessment of the suitability of the location to host a GDF for nuclear waste. The selection of a disposal site in the UAE would depend on a more detailed analysis of site-specific conditions.

The Art of Being Ethical and Responsible: Print Media Debate on Final Disposal of Spent Nuclear Fuel in Finland and Sweden

After decades of preparation, the final disposal of spent nuclear fuel has reached the construction stage in Finland, and the neighboring Sweden is likely to soon follow in the footsteps. These Nordic countries rely on a similar technical concept based on passive safety, advocated as a means of minimizing the burden to future generations. The scholarly literature on the ethics of nuclear waste management has thus far paid little attention to the views of the broader publics on the associated ethical challenges. This article helps to fill the gap through a longitudinal and comparative analysis of ethical discussion of the final disposal of SNF in news articles and letters to the editor in four leading Finnish and Swedish daily newspapers in 2008–2015. The study period included major milestones in the licensing processes of the respective two repository projects. The article examines the attention paid to intra- and intergenerational distributive and procedural justice, the changes in the ethical agenda over time, and the societal actor groups that receive attention in the media. The analysis reveals two distinct ethical media agendas: (1) the news article agenda that is dominated by framings of the main players (industry, politicians, authorities, and experts) and largely excludes future generations from the scope of justice, and (2) the agenda represented by the letters to the editor, which focuses on intergenerational justice concerns. Particularly, in the Finnish letters to the editor the value of the lives of distant future generations was discounted implicitly.

Post-Closure Safety Calculations for the Disposal of Spent Nuclear Fuel in a Generic Horizontal Drillhole Repository

The post-closure performance of a generic horizontal drillhole repository for the disposal of spent nuclear fuel (SNF) is quantitatively evaluated using a physics-based numerical model that accounts for coupled thermal-hydrological flow and radionuclide transport processes. The model incorporates most subcomponents of the repository system, from individual waste canisters to the geological far field. The main performance metric is the maximum annual dose to an individual drinking potentially contaminated water taken from a well located above the center of the repository. Safety is evaluated for a wide range of conditions and alternative system evolutions, using deterministic simulations, sensitivity analyses, and a sampling-based uncertainty propagation analysis. These analyses show that the estimated maximum annual dose is low (on the order of 10−4 mSv yr−1, which is 1000 times smaller than a typical dose standard), and that the conclusions drawn from this dose estimate remain valid even if considerable changes are made to key assumptions and property values. The depth of the repository and the attributes of its configuration provide the main safety function of isolation from the accessible environment. Long-term confinement of radionuclides in the waste matrix and slow, diffusion-dominated transport leading to long migration times allow for radioactive decay to occur within the repository system. These preliminary calculations suggest that SNF can be safely disposed in an appropriately sited and carefully constructed and sealed horizontal drillhole repository.

Knowledge about the Final Disposal of Nuclear Fuel in Sweden: Surveys to Members of Parliament and Citizens

In 2011, the Swedish Nuclear Fuel and Waste Management Company (SKB) applied for a permit to construct a disposal facility. The Swedish government is expected to make a decision in 2020. Three surveys have been conducted to investigate how informed the Swedish Members of Parliament (MP) and the citizens are in these issues. The first study with the MPs was done in 2013, the second in 2016 and the one with the citizens was conducted in the winter of 2018/2019. The results show that most MPs and half of the citizens were aware of the ongoing permission process. Rather surprisingly, there were more politicians and citizens who knew about the suggestions to use copper canisters, than knew the suggested location. In general, nuclear waste was seen as an important issue by all respondents. A majority of the MPs and the citizens believed that Sweden can dispose the waste in a safe manner. Among the citizens, the trust in politicians’ decisions on where and how to build a final repository were low and more trust was put into scientists and experts. Half of the citizens wanted to see a phase out of nuclear power, over half of the MPs meant that the repository should be designed so that the withdrawal of nuclear waste can be done.

Nonlinear Structural Analysis of the Spent Nuclear Fuel Disposal Canister Subjected to an Accidental Drop and Ground Impact Event

원자력발전의 최대 걸림돌은 사용 후 핵연료인 고준위폐기물이다. 높은 방사능과 발생하는 열은 사용 후 핵연료의 안전한 처분을 어렵게 하고 있다. 현재 유일한 처리방법은 심지층 처분기술이다. 본 논문은 이와 같은 심지층 처분기술의 핵심기술 중의 하나인 처분용기의 구조안전성 설계문제를 다루고 있다. 특히 처분장에서 처분용기 처분 시 사고로 운송차량에서 추락 낙하 하여 지면과 충돌하는 경우 처분용기에 가해지는 충격력에 의하여 처분용기에 발생하는 응력 및 변형에 대한 비선형구 조해석을 수행하였다. 해석의 주된 내용은 심지층 처분장에서 운반차량으로 처분용기 운반 중 사고로 추락낙하 하여 지면과의 충돌 시에 처분용기에 가해지는 충격력을 기구동역학해석 상용 컴퓨터코드인 RecurDyn으로 구하고 이 충격력에 의하여 처 분용기에 발생하는 응력 및 변형을 유한요소 정적 구조해석 상용 컴퓨터코드인 NISA를 이용하여 구한 것이다. 해석결과는 충돌 충격 시간 중 발생하여 처분용기에 가해지는 충격력에 의하여 처분용기, 특히 처분용기의 위 덮개 혹은 아래 덮개에 큰 응력과 대변형이 발생함을 보여주고 있다.

Overview of Finnish Spent Nuclear Fuel Disposal Programme

Overview of Finnish Spent Nuclear Fuel Disposal Programme

Comparative Study of Finite Element Analysis for Stresses Occurring in Various Models of the Spent Nuclear Fuel Disposal Canister due to the Accidental Drop and Impact on to the Ground

고준위폐기물 처분용기를 처분장에서 처분 시 사고로 운송차량에서 추락낙하 하여 지면과 충돌하는 경우 처분용기에 가 해지는 충격력에 의해 처분용기에 응력이 발생한다. 본 논문에서는 고준위폐기물 처분용기의 구조안전성 설계과정의 일환으 로 이와 같은 충격력에 의하여 여러 가지 처분용기 모델에 발생하는 응력에 대한 비교연구를 수행하였다. 연구의 주된 내용 은 이와 같은 비교연구를 통하여 구조적으로 건전한 처분용기의 설계에 관한 것이다. 처분장에서 운반차량으로 처분용기 운 반 중 사고로 추락낙하 하여 지면과의 충돌 시에 처분용기에 가해지는 충격력은 기구동역학해석 상용 컴퓨터코드인 RecurDyn으로 구하였다. 이렇게 구한 충격력에 의하여 여러 가지 처분용기 모델에 발생하는 응력 및 변형은 유한요소해석 상용 컴퓨터코드인 NISA를 이용하여 구하였다. 이 응력과 변형 값들의 비교 검토를 통하여 구조적으로 건전한 처분용기에 대한 연구를 수행하였다. 연구결과 처분용기 내부 고준위폐기물 다발을 감싸는 외곽 벽의 두께가 두꺼워 질수록 또는 처분 용기의 직경이 커질수록 처분용기에 발생하는 응력이 커지는 것을 알 수 있었다. 그러나 처분용기에 가해지는 충격력도 처 분용기의 직경이 커짐에 따라 증가하였다. 그럼에도 불구하고, 단위 충격력 당 발생하는 변형의 크기는 직경이 증가함에 따 라 감소하였다. 따라서 결론적으로 직경이 증가할수록 처분용기는 구조적으로 건전함을 알 수 있었다.

UNF-ST&DARDS Unified Database and the Automatic Document Generator

The U.S. Department of Energy, Office of Nuclear Energy is sponsoring development of a database to store information related to spent nuclear fuel (SNF) in support of its Spent Fuel and Waste Disposition efforts. This database, referred to as the Unified Database (UDB), is part of a larger engineering analysis tool, the Used Nuclear Fuel Storage, Transportation & Disposal Analysis Resource and Data System (UNF-ST&DARDS). The UDB provides a comprehensive, controlled source of SNF information, including dry cask attributes, assembly data, economic attributes, transportation infrastructure attributes, potential future facility attributes, and federal government radioactive waste attributes. There are a number of existing and envisioned data reports that can be expected to use data stored within the UDB; however, previously, there was not a streamlined method to couple the database to such data reports. Therefore, to streamline the creation of these reports, two methods were developed to generate documents from information in the database automatically. The first method used Java and LaTeX for automatically generating the report, and the second method used the Python programming language along with Sphinx, a Python documentation generator. There are some advantages and disadvantages to both approaches, but both methods produced equally high-quality, automatically generated reports that were directly coupled to the database. This paper describes data currently available in the UDB; explains the two different methods for automatically generating reports from these data; and shows examples of inline text, figures, and tables automatically generated using both approaches.

Shielding Analysis Capability of UNF-ST&DARDS

The Used Nuclear Fuel Storage, Transportation and Disposal Analysis Resource and Data System (UNF-ST&DARDS) is used to perform dose rate calculations for spent nuclear fuel (SNF) transportation packages based on the actual physical and nuclear characteristics (i.e., assembly design, burnup, initial enrichment, and cooling time) of the as-loaded SNF. Nuclear fuel data, transportation package model templates, and SNF canister loading map information residing within the tool facilitate automated generation of SCALE input files for radiation source term and dose rate calculations. Transportation package specific models developed for UNF-ST&DARDS dose rate analyses are described in detail. UNF-ST&DARDS dose rate analyses were performed for over 400 SNF canisters from 16 sites in their designated transportation casks. For simplicity, representative dose rate calculation results are presented as a function of time (i.e., selected calendar years between 2020 and 2100) for 73 SNF canisters in dry storage at four sites. For these canisters, the projected maximum dose rate values at 2 m from the lateral surfaces of the vehicle under normal conditions of transport (NCT) would vary between 1.9 and 11.5 mrem/h in 2020. Five SNF canisters will exceed the regulatory dose rate limit of 10 mrem/h at 2 m in 2020, and the analyzed SNF canisters will comply with regulatory dose rate limits by 2030. An analysis of the impact on the dose rate of fuel failure and reconfiguration during transportation indicated that the maximum dose rate for hypothetical accident conditions will be unaffected, and the NCT maximum dose rate at 2 m would have a maximum increase by a factor of 1.7 for a representative pressurized water reactor package and by a factor of 2.6 for a representative boiling water reactor package relative to intact fuel. Analysis of the actual heat loading and the dose rate at 2 m from the lateral surface of the vehicle for the five SNF canisters exceeding the NCT regulatory dose rate limit of 10 mrem/h in 2020 showed that the dose rate could be more limiting with respect to regulatory requirements than the heat loading; i.e., the canister transportability date may be evaluated based on the transportation package’s external dose rate.

Additional Capability Being Developed from UNF-ST&DARDS Unified Database: System Analysis and Fuel Cycle Option Analysis

The Used Nuclear Fuel Storage, Transportation & Disposal Analysis Resource and Data System (UNF-ST&DARDS) is being developed for the U.S. Department of Energy’s Office of Nuclear Energy by the national laboratories. An important part of UNF-ST&DARDS is the Unified Database (UDB), which contains information that can support a variety of activities including fuel storage, fuel transportation, and disposal-related system analysis. Currently, the main application of the UDB is to support evaluation of the characteristics of discharged spent nuclear fuel (SNF) from the U.S. commercial reactors. However, because of the extensive amount of data that has been collected and analyzed for UNF-ST&DARDS, there are many more applications that can utilize the UDB including system analysis with the Next-Generation System Analysis Model (NGSAM) and fuel cycle analysis with fuel cycle simulation codes such as ORION. Going forward, NGSAM and fuel cycle transition analysis with ORION integrate UDB data wherever possible in the UDB’s development plan. These advances in NGSAM and fuel cycle analysis can be used in conjunction with the UDB to help answer more complex questions about the optimization, utilization, storage, and eventual disposal of SNF.

Feasibility Studies on Pyro-SFR Closed Fuel Cycle and Direct Disposal of Spent Nuclear Fuel in Line with the Latest National Policy and Strategy of Korea

With a view to providing supportive information for the decision-making on the direction of the future nuclear energy systems in Korea (i.e., direct disposal or recycling of spent nuclear fuel) to be made around 2020, quantitative studies on the spent nuclear fuel (SNF) including transuranic elements (TRUs) and a series of economic analyses were conducted. At first, the total isotopic inventory of TRUs in the SNF to be generated from all thirty-six units of nuclear power plants in operation or under planning is estimated based on the Korean government’s official plan for nuclear power development. Secondly, the optimized deployment strategies are proposed considering the minimum number of sodium cooled-fast reactors (SFRs) needed to transmute all TRUs. Finally, direct disposal and Pyro-SFR closed nuclear energy systems were compared using equilibrium economic model and considering reduction of TRUs and electricity generation as benefits. Probabilistic economic analysis shows that the assumed total generation cost for direct disposal and Pyro-SFR closed nuclear energy systems resides within the range of 13.60~33.94 mills/kWh and 11.40~25.91 mills/kWh, respectively. Dominant cost elements and the range of SFR overnight cost which guarantees the economic feasibility of the Pyro-SFR closed nuclear energy system over the direct disposal option were also identified through sensitivity analysis and break-even cost estimation.

The Regulations of Japan on the Facility for the Disposal of Spent Nuclear Fuel and the Implications Thereof

The Regulations of Japan on the Facility for the Disposal of Spent Nuclear Fuel and the Implications Thereof

Analytical Closed Form Solution for the Impact Load of a Collision between Rigid Bodies and its Application to a Spent Nuclear Fuel Disposal Canister Accidentally Dropped and Impacted on the Ground: Application(Numerical Analysis)

Analytical Closed Form Solution for the Impact Load of a Collision between Rigid Bodies and its Application to a Spent Nuclear Fuel Disposal Canister Accidentally Dropped and Impacted on the Ground: Application(Numerical Analysis)

Socio‐Technical Challenges of Finland's Nuclear Waste Policy: Discussion of the Techno‐Scientific Community on the Geological Disposal of Spent Nuclear Fuel

AbstractThe objective of the paper is to study different views on the future challenges that the geological disposal of spent nuclear fuel (SNF) will encounter. We investigate how engineers, natural scientists, representatives of the nuclear industry, regulators, and laypersons from non‐governmental organizations perceive the remaining socio‐technical challenges for implementing geological disposal by examining discussions in a professional magazine covering nuclear waste management issues. The paper focuses on the post‐site selection phase associated with the planned disposal facility at Olkiluoto in Finland. This phase (between 1999 and 2010) represents the period after the nuclear waste management company Posiva submitted the Decision‐in‐Principle (DiP) application for the final disposal facility for SNF in 1999 and the ratification of the DiP regarding the final disposal of SNF by the Finnish Parliament in May 2001. The paper provides a theoretical elaboration of the term socio‐technical that will lay the foundation for empirical analysis as well as a brief overview of the state of affairs regarding the Finnish SNF management program. Results show that market actors were clearly the most active players in defining and discussing final disposal. Qualitative analysis identified six kinds of socio‐technical challenges: socio‐technical regime challenges, social acceptance challenges, knowledge challenges, safety challenges, construction challenges, and flexibility challenges.

Finite Element Analysis of Transient Heat Transfer in and around a Deep Geological Repository for a Spent Nuclear Fuel Disposal Canister and the Heat Generation of the Spent Nuclear Fuel

This paper presents a finite element analysis of transient heat transfer in and around a hypothetical deep geological repository for a spent nuclear fuel (SNF) disposal canister and the heat generation of the SNF inside the canister to provide basic information for dimensioning the repository and configuring the repository components. Three geometric models are compared to determine the most suitable assuming the periodic allocation of boreholes where canisters are deposited. These models consist of several different material regions. Each model is horizontally limited to a region around and including a single canister, bounded by midsurfaces with variant distances between adjacent deposition tunnels and adjacent canisters, and vertically bounded by the ground surface located 500 m above the deposition tunnel and the surface located 500 m below the bottom of the borehole. Using a commercial finite element analysis code and detailed realistic finite element models of repository components, transient heat transfer analyses are carried out for up to 1000 yr after deposition of the canister into the repository. Time-dependent temperature curves at selected positions are obtained for each geometric model. Various temperature distribution changes of material regions in geometric models are also obtained.

A Container Based on Polymer Composite Materials for the Ultimate Disposal of Spent Nuclear Fuel and Radioactive Waste

This work demonstrates the feasibility of fabricating containers for the ultimate disposal of spent nuclear reactor fuel and high-level radioactive waste using polymer-based composite materials. The study has identified three engineering polymers suitable for this demanding application: polyetheretherketone (PEEK), polyetherimide (PEI), and polysulfone (PSU). PEEK and PEI are used as composite materials components, with 30% carbon and glass fiber, respectively, whereas PSU is used as a virgin (nonreinforced) material. The rationale for the choice of polymer composites comes from their superior physical, mechanical, and chemical performance, in addition to their economical advantage. In particular, they display better resistance to corrosion and to structural weakening from irradiation.Scaled-down containers were fabricated using these materials. They were subjected to a battery of tests under conditions similar to those expected for the disposal environment of actual radioactive waste–filled containers. In particular, the container models were irradiated in the pool of a SLOWPOKE-2 nuclear research reactor, accumulating doses from a mixed-radiation field that were comparable to total doses accumulated over 500 yr at a deep underground waste repository site. Mechanical compression tests mimicked the large hydrostatic pressures incurred from granite rock at depths of some 1000 m within the Canadian Shield.Several composite materials were tested, and for the three engineering materials listed above, some of the results are as follows:1. variation in elastic modulus following a 28.9-kGy radiation dose—PEEK, −6.66% ± 0.47%; PEI, +5.63% ± 0.23%; PSU, +3.16% ± 0.13%2. compression results for the irradiated container models and load at break and strain—PEEK, 2.152 MPa and 1178 μmm-1; PEI, 1.236 MPa and 1171 μmm-1; PSU, 1.190 MPa and 2576 μmm-1, respectively3. cost analysis—costs for the fabrication of the prototype containers based on PEEK, $273610; PEI, $145920; PSU, $257460.The work also provided insight into potential problems in the fabrication of full-sized containers and into the best fabrication methods to adopt. The method of filament winding would be more appropriate for the PEEK- and the PEI-based composite materials, while blow forming would be the preferred method for the PSU material. In particular, this research could determine the best way to design the container lids.

Advanced Polymer Composites for the Fabrication of Spent Nuclear Fuel Disposal Containers

In Canada, the spent nuclear fuel disposal method proposed is to permanently isolate the spent fuel in deep underground vaults carved in stable granite rock formations within the Canadian Shield, with the integrity of the isolation to be assured for a minimum period of 500 yr. The present work aims at determining the feasibility of using a consolidated composite material made of an advanced polymer called PEEK (Poly Ether Ether Ketone) and continuous graphite fiber to fabricate a container designed to isolate the spent nuclear fuel from the biosphere for such very long time periods. The research focused on submitting the PEEK-based composite material to a thermal and radioactive environment comparable to, and, in some aspects, more aggressive than, the conditions of exposure in the disposal vault. The changes to the physical, mechanical, and chemical properties of the material following prolonged exposure were then determined. The simulation of the environment was achieved by irradiating numerous test specimens in a mixed radiation field produced by a SLOWPOKE-2 nuclear research reactor at controlled ambient temperatures ranging from ˜20 to 75°C. The specimens were characterized via several methods: tensile and flexural testing, differential scanning calorimetry, scanning electron microscopy, and wide-angle X-ray scattering. The results confirmed that the PEEK-based composite material was resistant to exposure to high radiation doses (1 MGy), at temperatures between ˜20 and 75°C. The mechanical and other properties were barely affected, with values rarely exceeding 1σ of the properties of nonirradiated samples, suggesting that the PEEK–graphite fiber composite material can indeed be considered as a very good candidate for this demanding application.