Download or read book Microscopic Examination of a Corrosion Front in Spent Nuclear Fuel written by R. J. Finch and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Spent uranium oxide nuclear fuel hosts a variety of trace chemical constituents, many of which must be sequestered from the biosphere during fuel storage and disposal. In this paper we present synchrotron x-ray absorption spectroscopy and microscopy findings that illuminate the resultant local chemistry of neptunium and plutonium within spent uranium oxide nuclear fuel before and after corrosive alteration in an air-saturated aqueous environment. We find the plutonium and neptunium in unaltered spent fuel to have a +4 oxidation state and an environment consistent with solid-solution in the UO{sub 2} matrix. During corrosion in an air-saturated aqueous environment, the uranium matrix is converted to uranyl U(VI)O{sub 2}{sup 2+} mineral assemblage that is depleted in plutonium and neptunium relative to the parent fuel. At the corrosion front interface between intact fuel and the uranyl-mineral corrosion layer, we find evidence of a thin ({approx}20 micrometer) layer that is enriched in plutonium and neptunium within a predominantly U{sup 4+} environment. Available data for the standard reduction potentials for NpO{sup 2+}/Np{sup 4+} and UO{sub 2}{sup 2+}/U{sup 4+} couples indicate that Np(IV) may not be effectively oxidized to Np(V) at the corrosion potentials of uranium dioxide spent nuclear fuel in air-saturated aqueous solutions. Neptunium is an important radionuclide in dose contribution according to performance assessment models of the proposed U.S. repository at Yucca Mountain, Nevada. A scientific understanding of how the UO{sub 2} matrix of spent nuclear fuel impacts the oxidative dissolution and reductive precipitation of neptunium is needed to predict its behavior at the fuel surface during aqueous corrosion. Neptunium would most likely be transported as aqueous Np(V) species, but for this to occur it must first be oxidized from the Np(IV) state found within the parent spent nuclear fuel [1]. In the immediate vicinity of the spent fuel's surface the redox and nucleation behavior is likely to promote/enhance nucleation of NpO{sub 2} and Np{sub 2}O{sub 5}. Alternatively, Np may be incorporated into uranyl (UO{sub 2}{sup 2+}) alteration phases [2]. In some cases, less-soluble elements such as plutonium will be enriched near the surface of the corroding fuel [3]. We have used focused synchrotron x-rays from the MRCAT beam line at the Advanced Photon Source (APS) at Argonne National Lab to examine a specimen of spent nuclear fuel that had been subject to 10 years of corrosion testing in an environment of humid air and dripping groundwater at 90 C [4]. We find evidence of a region, approximately 20 microns in thickness, enriched in plutonium and neptunium at the corrosion front that exists between the uranyl silicate alteration mineral rind and the unaltered uranium oxide fuel (Figures 1 and 2). The uranyl silicate is itself found to be depleted in these transuranic elements relative to their abundance relative to uranium in the parent fuel. This suggests a low mobility of these components owing to a resistance to oxidize further in the presence of a UO{sub 2}{sup 2+}/U{sup 4+} couple [5].

Download or read book Corrosion of Spent Nuclear Fuel written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The successful disposal of spent nuclear fuel (SNF) is one of the most serious challenges to the success of the nuclear fuel cycle and the future of nuclear power generation. Spent nuclear fuel is essentially UO2 with approximately 4-5 atomic percent actinides and fission product elements. A number of these elements have long half-lives (239Pu: 24,100 years; 237Np: 2 million years; 129I: 16 million years; 79Se: 1.1 million years; 99Tc 200,000 years); hence, the long-term behavior of the UO2 is an essential concern in the evaluation of the safety of a repository for spent nuclear fuel. One of the unique and scientifically most difficult aspects of the successful disposal of spent nuclear fuel is the extrapolation of short-term laboratory data (hours to years) to the long time periods (103 to 105 years). The direct verification of these extrapolations or interpolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the public that there is a reasonable basis for accepting the long-term extrapolations of spent fuel behavior. In recent years ''natural analogues'' for both the repository environment (e.g., the Oklo natural reactors) and nuclear waste form behavior (e.g., corrosion and alteration of uraninite, UO2+x) have been cited as a fundamental means of achieving confirmation of long-term extrapolations. In particular, considerable effort has already been made to establish that uraninite, UO2+x, with its impurities, is a good structural and chemical analogue for the analysis of the long-term behavior of the UO2 in spent nuclear fuel. This research program is based on the study of uraninite and the naturally occurring alteration products of UO2+x under oxidizing and reducing conditions. We address the following issues: (1) What are the long-term corrosion products of natural UO2+x under reducing and oxidizing conditions? (2) What is the paragenesis or the reaction path of the phases that form during alteration? How is the paragenetic sequence of formation related to the structures and compositions of the phases? (3) What is the trace element content in the corrosion products (as compared with the original UO2), and does the trace element content substantiate models developed to predict radionuclide incorporation? (4) Are the corrosion products the phases that are predicted from reaction path models (e.g., EQ3/6) that are used in performance assessments? (5) How persistent over time are the metastable phase assemblages that form? Will these phases serve as barriers to radionuclide release? (6) Based on the structures of these phases (mostly sheet structures) can the thermodynamic stabilities of these phases be estimated, or at least bounded, in such a way as to provide for a convincing and substantive performance assessment?

Download or read book Site Characterization Progress Report written by and published by . This book was released on 1997 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Corrosion Testing of Spent Nuclear Fuel Performed at Argonne National Laboratory for Repository Acceptance written by and published by . This book was released on 2000 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion tests of DOE-owned spent nuclear fuel are performed at Argonne National Laboratory to support the license application for the Yucca Mountain Repository. The tests are designed to determine corrosion rates and degradation products formed when fuel is reacted at elevated temperature in different aqueous environments, including vapor, dripping water, submersion, and liquid film contact. Corrosion rates are determined from the quantity of radionuclides released from wetted fuel and from the weight loss of the test fuel specimen as a function of time. Degradation products include secondary mineral phases and dissolved, adsorbed, and colloidal species. Solid phase examinations determine fuel/mineral interface relationships, characterize radionuclide incorporation into secondary phases, and determine corrosion mechanisms at grain interfaces within the fuel. Leachate solution analyses quantify released radionuclides and determine the size and charge distribution of colloids. This paper presents selected results from corrosion tests on metallic fuels.

Download or read book Geologic Repository for Disposal of Spent Nuclear Fuel and High level Radioactive Waste at Yucca Mountain written by and published by . This book was released on 1999 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water written by International Atomic Energy Agency and published by . This book was released on 2003 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes research performed in ten laboratories within the framework of the IAEA Co-ordinated Research Project on Corrosion of Research Reactor Aluminium Clad Spent Fuel in Water. The project consisted of exposure of standard racks of corrosion coupons in the spent fuel pools of the participating research reactor laboratories and evaluation of the coupons after predetermined exposure times, along with periodic monitoring of the storage water. A group of experts in the field contributed a state of the art review and provided technical supervision of the project. Localized corrosion mechanisms are notoriously difficult to understand, and it was clear from the outset that obtaining consistency in the results and their interpretation from laboratory to laboratory would depend on the development of an excellent set of experimental protocols. These experimental protocols are described in the report, together with guidelines for the maintenance of optimum water chemistry to minimize the corrosion of aluminium clad research reactor fuel in wet storage.

Download or read book The SKB Spent Fuel Corrosion Programme written by Roy Forsyth and published by . This book was released on 1997 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spent Nuclear Fuel Corrosion written by Ronald Stewart Forsyth and published by . This book was released on 1994 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Corrosion of Spent Nuclear Fuel written by Rodney C. Ewing and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program is a broadly based effort to understand the long-term behavior of spent nuclear fuel (SNF) and its alteration products in a geologic repository. We have established by experiments and field studies that natural uraninite, UO2+x, and its alteration products are excellent ''natural analogues'' for the study of the corrosion of UO2 in SNF. This on-going research program has addressed the following major issues: (1) What are the long-term corrosion products of natural UO2+x, uraninite, under oxidizing and reducing conditions? (2) What is the paragenesis or the reaction path for the phases that form during alteration? (3) What is the radionuclide content in the corrosion products as compared with the original UO2+x? Do the trace element contents substantiate models developed to predict radionuclide incorporation into the secondary phases? Are the corrosion products accurately predicted from geochemical codes (e.g., EQ3/6 or Geochemist's Workbench) that are used in performance assessments? Can these codes be tested by studies of natural analogue sites (e.g., Oklo, Cigar Lake or Pena Blanca).

Download or read book Spent Nuclear Fuel Corrosion The Application of ICP MS Todirect Actinide Analysis written by U. -B. Eklund and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Corrosion of Aluminum clad Spent Nuclear Fuel in Wet Basin Storage written by and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments for Evaluation of Corrosion to Develop Storage Criteria for Interim Dry Storage of Aluminum alloy Clad Spent Nuclear Fuel written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radiation Induced Corrosion of Spent Nuclear Fuel written by Jessica Higgins and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific Basis for Nuclear Waste Management XXX written by Darrel E. Dunn and published by . This book was released on 2007 with total page 672 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 1993 with total page 1052 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.

Download or read book Microbiology of Extreme and Human Made Confined Environments Spacecraft Space Stations Cleanrooms and Analogous Sites written by Rakesh Mogul and published by Frontiers Media SA. This book was released on 2022-06-07 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structural Materials for Generation IV Nuclear Reactors written by Pascal Yvon and published by Woodhead Publishing. This book was released on 2016-08-27 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt: Operating at a high level of fuel efficiency, safety, proliferation-resistance, sustainability and cost, generation IV nuclear reactors promise enhanced features to an energy resource which is already seen as an outstanding source of reliable base load power. The performance and reliability of materials when subjected to the higher neutron doses and extremely corrosive higher temperature environments that will be found in generation IV nuclear reactors are essential areas of study, as key considerations for the successful development of generation IV reactors are suitable structural materials for both in-core and out-of-core applications. Structural Materials for Generation IV Nuclear Reactors explores the current state-of-the art in these areas. Part One reviews the materials, requirements and challenges in generation IV systems. Part Two presents the core materials with chapters on irradiation resistant austenitic steels, ODS/FM steels and refractory metals amongst others. Part Three looks at out-of-core materials. Structural Materials for Generation IV Nuclear Reactors is an essential reference text for professional scientists, engineers and postgraduate researchers involved in the development of generation IV nuclear reactors. - Introduces the higher neutron doses and extremely corrosive higher temperature environments that will be found in generation IV nuclear reactors and implications for structural materials - Contains chapters on the key core and out-of-core materials, from steels to advanced micro-laminates - Written by an expert in that particular area