Download or read book Nuclear Criticality Safety Analysis of a Spent Fuel Waste Package in a Tuff Repository written by B. H. Weren and published by . This book was released on 1983 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: An assessment has been performed of the criticality potential associated with the disposal of spent fuel in a tuff geology above the water table. Eleven potential configurations were defined which cover a vast range of geometries and conditions from the nominal configuration at emplacement to a hypothetical configuration thousands of years after emplacement in which the structure is gone, the fuel pellets disintegrated and the borehole flooded. Of these eleven configurations, four have been evaluated at this time. The results of this evaluation indicate that even with very conservative assumptions (4.5 w/o fresh fuel), criticality is not a problem for the nominal configuration either dry or fully flooded. In the cases where the condition of the waste package is assumed to have severely deteriorated, over long times, calculations were performed with less conservative assumptions (depleted fuel). An assessment of these calculations indicates that criticality safety could be demonstrated if the depletion of the fissile inventory during fuel irradiation is taken into account. A detailed discussion of the calculations performed is presented in this report. Also included are a description of the configurations which were considered, the analytical methods and models used, and a discussion of additional related work which should be performed.

Download or read book Nuclear Criticality Safety Analysis of a Spent Fuel Waste Package in a Tuff Repository written by and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: An assessment has been performed of the criticality potential associated with the disposal of spent fuel in a tuff geology above the water table. Eleven potential configurations were defined which cover a vast range of geometries and conditions from the nominal configuration at emplacement to a hypothetical configuration thousands of years after emplacement in which the structure is gone, the fuel pellets disintegrated and the borehole flooded. Of these eleven configurations, four have been evaluated at this time. The results of this evaluation indicate that even with very conservative assumptions (4.5 w/o fresh fuel), criticality is not a problem for the nominal configuration either dry or fully flooded. In the cases where the condition of the waste package is assumed to have severely deteriorated, over long times, calculations were performed with less conservative assumptions (depleted fuel). An assessment of these calculations indicates that criticality safety could be demonstrated if the depletion of the fissile inventory during fuel irradiation is taken into account. A detailed discussion of the calculations performed is presented in this report. Also included are a description of the configurations which were considered, the analytical methods and models used, and a discussion of additional related work which should be performed. 15 references, 11 figures, 8 tables.

Download or read book Preclosure Analysis of Conceptual Waste Package Designs for Nuclear Waste Repository in Tuff written by W. C. O'Neal and published by . This book was released on 1984 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Consideration of Criticality in a Nuclear Waste Repository written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The preliminary criticality analysis that was done suggests that the possibility of achieving critical conditions cannot be easily ruled out without looking at the geochemical process of assembly or the dynamics of the operation of a critical assembly. The evaluation of a critical assembly requires an integrated, consistent approach that includes evaluating the following: (1) the alteration rates of the layers of the container and spent fuel, (2) the transport of fissile material or neutron absorbers, and (3) the assembly mechanisms that can achieve critical conditions. The above is a non-trivial analysis and preliminary work suggests that with the loading assumed, enough fissile mass will leach from the HEU multi-purpose canisters to support a criticality. In addition, the consequences of an unpressurized Oklo type criticality would be insignificant to the performance of an unsaturated, tuff repository.

Download or read book Scientific Basis for Nuclear Waste Management XVI Volume 294 written by Charles G. Interrante and published by Mrs Proceedings. This book was released on 1993-03-26 with total page 1006 pages. Available in PDF, EPUB and Kindle. Book excerpt: The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners. This book was first published in 1993.

Download or read book Intact and Degraded Criticality Calculations for the Codisposal of Shippingport LWBR Spent Nuclear Fuel in a Waste Package written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this calculation is to characterize the nuclear criticality safety concerns associated with the codisposal of the U.S. Department of Energy's (DOE) Shippingport Light Water Breeder Reactor (SP LWBR) Spent Nuclear Fuel (SNF) in a 5-Defense High-Level Waste (5-DHLW) Waste Package (WP), which is to be placed in a Monitored Geologic Repository (MGR). The scope of this calculation is limited to the determination of the effective neutron multiplication factor (K{sub eff}) for intact- and degraded-mode internal configurations of the codisposal WP containing Shippingport LWBR seed-type assemblies. The results of this calculation will be used to evaluate criticality issues and support the analysis that is planed to be performed to demonstrate the viability of the codisposal concept for the MGR. This calculation is associated with the waste package design and was performed in accordance with the DOE SNF Analysis Plan for FY 2000 (See Ref. 22). The document has been prepared in accordance with the Administrative Procedure AP-3.12Q, Calculations (Ref. 23).

Download or read book Behavior of Carbon 14 in Waste Packages for Spent Fuel in a Repository in Tuff Revision 1 written by and published by . This book was released on 1984 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of gas from a heated air-filled canister containing a spent fuel assembly before and after rupture of a fuel rod shows that about 1.5 mCi of 14C from the external surface of the assembly was rapidly oxidized and released as 14CO2 in excess oxygen at 275°C and 104/sup rad/h. After rupture, an additional 0.3 mCi was released, probably also from the external surface. The total 14C inventory in the entire 15 x 15 rod assembly including structural hardware is estimated to be 690 mCi. These measurements indicate that account will have to be taken of the time distribution of lifetimes of the canisters, and a broad definition of the "engineered system" may be necessary, in order to meet 10CFR60 requirements with spent fuel in a repository in tuff. 22 refs., 1 tab.

Download or read book Criticality Safety Study for the Disposal of Spent Nuclear Fuel in Water Saturated Geologic Repository written by Xudong Liu and published by . This book was released on 2016 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Damaged fuels originated from the accident at the Fukushima-Daiichi Nuclear Power Station, and the spent nuclear fuels from commercial light water reactors (LWRs) in Japan are considered to be disposed of in deep geological repository. For a prospective repository, as part of generic performance assessment, a criticality safety assessment (CSA) should be performed to ensure that the repository system including the engineered barriers and host geological formations remains sub-critical for tens of thousands to millions of years. For various repository concepts, CSA is considered to include three major stages in chronological order: (1) the stage before package failure, (2) the stage after package failure, while fissile nuclides remain within the engineered barrier system (EBS) and in the near-field region, and (3) the stage in which fissile nuclides originated from multiple packages are deposited in far-field host rocks. Defining the model for neutronics calculations plays a central role in CSAs, where conservative assumptions are usually made to cope with various uncertainties and to simplify the model. The aim of this dissertation is to develop neutronics models for different stages in the criticality safety study, and provide basic understandings for the long-term criticality safety for the disposal of spent nuclear fuel in geologic repository. In the near-field analysis, a neutronics model has been developed for a system consisting of a canister containing fuel debris from Fukushima reactors and the surrounding buffer, in a water-saturated deep geological repository. The fuel debris has been modeled as a hexagonal lattice of spherical fuel particles. Following key observations have been concluded from the numerical results: (a) the calculated neutron multiplicity (keff) is sensitively dependent on assumptions related to moderation, (b) the carbon steel canister plays an important role in reducing the potential for criticality, (c) the maximum keff of the canister-buffer system could be achieved after a fraction of fissile nuclides been released from the canister, and (d) under several assumptions, the maximum keff of the canister-buffer system could be principally determined by the dimension and composition of the canister, not by the initial fuel loading. Based on the preliminary results and findings, a parametric study has been made to identify the optimized lattice parameters for criticality. And the critical mass of damaged fuels for a single canister has been calculated. If this critical mass is used as the maximum canister mass loadings, roughly a thousand canisters are needed to contain the damaged fuels from the three damaged cores. For the LWR spent fuels, a parametric study has been performed to examine spent fuels with different designs and burnup histories. The numerical results indicate that, under the conditions assumed, for all UO2 spent fuels and most of the MOX spent fuels, the single canister model will always be subcritical. The far-field study has been focusing on neutronic analysis to examine the criticality conditions for uranium depositions in geological formations which result from geological disposal of damaged fuels from Fukushima reactors. Neutronics models are used to evaluate the keff and critical mass for various combinations of host rock and geometries. The present study has revealed that the planar fracture geometry applied in the previous criticality safety assessment for geological disposal would not necessarily yield conservative results against the homogeneous uranium deposition. It has been found that various far-field critical configurations are conceivable for given conditions of materials and geological formations. Prior to knowing the site location, some important points for selecting a site for criticality safety can be suggested. These include: (a) iron existing in the host rock reduces the likelihood of criticality significantly; (b) low host rock porosity is preferred for criticality safety; (c) the conservatism could change when comparing heterogeneous geometries for different fracture apertures; and (d) the importance of the mass of the deposition increases when it is smaller. As part of the improvement for the models developed in the far-field analysis, preliminary works on uranium depositions in randomly fractured rocks have been presented. The randomly fractured geometry could fundamentally influence the far-field criticality, because the system's keff value sensitively depends on the fracture aperture and the depositions at fracture intersections. No previous work has been made to study the effect of random geometry in the context of the long-term criticality safety in a geologic repository. Different numerical schemes have been developed and compared for the direct sampling of uranium depositions in randomly fractured rocks using MCNP. A general literature review of existing methods for neutron transport problems with random processes has been made. And the analytical Feinberg-Galanin-Horning (FGH) method has been derived and tested for a numerical example.

Download or read book Scientific Basis for Nuclear Waste Management XVII written by Materials Research Society and published by . This book was released on 1993 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book INIS Atomindex written by and published by . This book was released on 1995 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Criticality Safety Issues Associated with the Burial of Highly Enriched Nuclear Fuel in a Geologic Repository written by and published by . This book was released on 1992 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to provide some basic guidance regarding the criticality safety implications associated with long term burial of highly enriched nuclear fuel in a geologic repository. Generic calculations to determine the distance required to neutronically isolate neighboring fissile regions are reported. Two specific fuels are also addressed, Fort Saint Vrain and Shippingport PWR Core-2 Seed-2 (PWR). These fuels are addressed under both dry and flooded conditions. Fort Saint Vrain fuel contains a uranium-graphite fuel matrix, is graphite moderated and has a relatively low 235U loading (∼1 kg per element). PWR contains a uranium-zirconium fuel matrix, is water moderated, zircaloy clad and has a 235U loading of ∼15 kg per cluster. These two fuels are representative of many of the fuels currently stored at the Idaho Chemical Processing Plant (ICPP). The spent fuel storage system under consideration involves filling cylindrical canisters with spent nuclear fuel. These canisters are then to be placed into a geologic repository. Salt and tuff are the two most likely materials in which the canisters will be buried. Canisters will require sufficient material between them to ensure that the overall reactivity stays within acceptable limits. Fuels will also have to be shown to be critically safe under a variety of conditions. These conditions include flooding and the loss of the physical integrity of the fuel.

Download or read book Safety Related Issues of Spent Nuclear Fuel Storage written by North Atlantic Treaty Organization. Public Diplomacy Division and published by Springer Science & Business Media. This book was released on 2007-05-09 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains papers from a NATO-sponsored workshop in Almaty in September 2005, which discussed safety-related issues of storing spent nuclear fuel. Fifteen papers cover aluminum-clad fuel discharged from research reactors worldwide, while five papers examine stainless steel-clad fuel from fast reactors, and two Zircaloy-clad fuel from commercial light-water reactors.

Download or read book Preclosure Criticality Analysis Process Report written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design approach for criticality of the disposal container and waste package will be dictated by existing regulatory requirements. This conclusion is based on the fact that preclosure operations and facilities have significant similarities to existing facilities and operations currently regulated by the NRC. The major difference would be the use of a risk-informed approach with burnup credit. This approach could reduce licensing delays and costs of the repository. The probability of success for this proposed seamless licensing strategy is increased, since there is precedence of regulation (10 CFR Part 63 and NUREG 1520) and commercial precedence for allowing burnup credit at sites similar to Yucca Mountain during preclosure. While NUREG 1520 is not directly applicable to a facility for handling spent nuclear fuel, the risk-informed approach to criticality analysis in NUREG 1520 is considered indicative of how the NRC will approach risk-informed criticality analysis at spent fuel facilities in the future. The types of design basis events which must be considered during the criticality safety analysis portion of the Integrated Safety Analysis (ISA) are those events which result in unanticipated moderation, loss of neutron absorber, geometric changes in the critical system, or administrative errors in waste form placement (loading) of the disposal container. The specific events to be considered must be based on the review of the system's design, as discussed in Section 3.2. A transition of licensing approach (e.g., deterministic versus risk-informed, performance-based) is not obvious and will require analysis. For commercial spent nuclear fuel, the probability of interspersed moderation may be low enough to allow nearly the same Critical Limit for both preclosure and postclosure, though an administrative margin will be applied to preclosure and possibly not to postclosure. Similarly the Design Basis Events for the waste package may be incredible and therefore not re quire an administrative margin, or at least one that is less than the one used currently (0.05) for all waste forms (e.g., CRWMS M and O 1999c, criteria 1.2.1.5, p. 10.) In this case, the margin-to-criticality for preclosure and postclosure in the subsurface facility would be closer to that used for postclosure (if any). This would facilitate a seamless transition, including the use of burnup credit.

Download or read book Geological Repository Systems for Safe Disposal of Spent Nuclear Fuels and Radioactive Waste written by Michael J Apted and published by Woodhead Publishing. This book was released on 2017-05-25 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geological Repository Systems for Safe Disposal of Spent Nuclear Fuels and Radioactive Waste, Second Edition, critically reviews state-of-the-art technologies and scientific methods relating to the implementation of the most effective approaches to the long-term, safe disposition of nuclear waste, also discussing regulatory developments and social engagement approaches as major themes. Chapters in Part One introduce the topic of geological disposal, providing an overview of near-surface, intermediate depth, and deep borehole disposal, spanning low-, medium- and high-level wastes. Part Two addresses the different types of repository systems – crystalline, clay, and salt, also discussing methods of site surveying and construction. The critical safety issue of engineered barrier systems is the focus of Part Three, with coverage ranging from nuclear waste canisters, to buffer and backfill materials. Lastly, Parts Four and Five focus on safety, security, and acceptability, concentrating on repository performance assessment, then radiation protection, environmental monitoring, and social engagement. Comprehensively revised, updated, and expanded with 25% new material on topics of current importance, this is the standard reference for all nuclear waste management and geological repository professionals and researchers. Contains 25% more material on topics of current importance in this new, comprehensive edition Fully updated coverage of both near-surface/intermediate depth, and deep borehole disposal in one convenient volume Goes beyond the scientific and technical aspects of disposal to include the political, regulatory, and societal issues involved, all from an international perspective

Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1983 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Yucca Mountain Site Characterization Project Bibliography 1992 1993 written by and published by . This book was released on 1994 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: