Download or read book Accident Source Terms for Pressurized Water Reactors with High burnup Cores Calculated Using MELCOR 1 8 5 written by and published by . This book was released on 2010 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, risk-significant pressurized-water reactor severe accident sequences are examined using MELCOR 1.8.5 to explore the range of fission product releases to the reactor containment building. Advances in the understanding of fission product release and transport behavior and severe accident progression are used to render best estimate analyses of selected accident sequences. Particular emphasis is placed on estimating the effects of high fuel burnup in contrast with low burnup on fission product releases to the containment. Supporting this emphasis, recent data available on fission product release from high-burnup (HBU) fuel from the French VERCOR project are used in this study. The results of these analyses are treated as samples from a population of accident sequences in order to employ approximate order statistics characterization of the results. These trends and tendencies are then compared to the NUREG-1465 alternative source term prescription used today for regulatory applications. In general, greater differences are observed between the state-of-the-art calculations for either HBU or low-burnup (LBU) fuel and the NUREG-1465 containment release fractions than exist between HBU and LBU release fractions. Current analyses suggest that retention of fission products within the vessel and the reactor coolant system (RCS) are greater than contemplated in the NUREG-1465 prescription, and that, overall, release fractions to the containment are therefore lower across the board in the present analyses than suggested in NUREG-1465. The decreased volatility of Cs2MoO4 compared to CsI or CsOH increases the predicted RCS retention of cesium, and as a result, cesium and iodine do not follow identical behaviors with respect to distribution among vessel, RCS, and containment. With respect to the regulatory alternative source term, greater differences are observed between the NUREG-1465 prescription and both HBU and LBU predictions than exist between HBU and LBU analyses. Additionally, current analyses suggest that the NUREG-1465 release fractions are conservative by about a factor of 2 in terms of release fractions and that release durations for in-vessel and late in-vessel release periods are in fact longer than the NUREG-1465 durations. It is currently planned that a subsequent report will further characterize these results using more refined statistical methods, permitting a more precise reformulation of the NUREG-1465 alternative source term for both LBU and HBU fuels, with the most important finding being that the NUREG-1465 formula appears to embody significant conservatism compared to current best-estimate analyses.
Download or read book Assessment of Severe Accident Source Terms in Pressurized water Reactors with a 40 Mixed oxide and 60 Low enriched Uranium Core Using MELCOR 1 8 5 written by and published by . This book was released on 2010 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of a Nuclear Regulatory Commission (NRC) research program to evaluate the impact of using mixed-oxide (MOX) fuel in commercial nuclear power plants, a study was undertaken to evaluate the impact of the usage of MOX fuel on the consequences of postulated severe accidents. A series of 23 severe accident calculations was performed using MELCOR 1.8.5 for a four-loop Westinghouse reactor with an ice condenser containment. The calculations covered five basic accident classes that were identified as the risk- and consequence-dominant accident sequences in plant-specific probabilistic risk assessments for the McGuire and Catawba nuclear plants, including station blackouts and loss-of-coolant accidents of various sizes, with both early and late containment failures. Ultimately, the results of these MELCOR simulations will be used to provide a supplement to the NRC's alternative source term described in NUREG-1465. Source term magnitude and timing results are presented consistent with the NUREG-1465 format. For each of the severe accident release phases (coolant release, gap release, in-vessel release, ex-vessel release, and late in-vessel release), source term timing information (onset of release and duration) is presented. For all release phases except for the coolant release phase, magnitudes are presented for each of the NUREG-1465 radionuclide groups. MELCOR results showed variation of noble metal releases between those typical of ruthenium (Ru) and those typical of molybdenum (Mo); therefore, results for the noble metals were presented for Ru and Mo separately. The collection of the source term results can be used as the basis to develop a representative source term (across all accident types) that will be the MOX supplement to NUREG-1465.
Download or read book Accident Source Terms for Boiling Water Reactors with High Burnup Cores written by and published by . This book was released on 2007 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this report is to provide the technical basis for development of recommendations for updates to the NUREG-1465 Source Term for BWRs that will extend its applicability to accidents involving high burnup (HBU) cores. However, a secondary objective is to re-examine the fundamental characteristics of the prescription for fission product release to containment described by NUREG-1465. This secondary objective is motivated by an interest to understand the extent to which research into the release and behaviors of radionuclides under accident conditions has altered best-estimate calculations of the integral response of BWRs to severe core damage sequences and the resulting radiological source terms to containment. This report, therefore, documents specific results of fission product source term analyses that will form the basis for the HBU supplement to NUREG-1465. However, commentary is also provided on observed differences between the composite results of the source term calculations performed here and those reflected NUREG-1465 itself.
Download or read book Accident Source Terms for Light Water Nuclear Power Plants written by U.s. Nuclear Reglatory Commission and published by CreateSpace. This book was released on 2014-06-06 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1962, the Atomic Energy Commission issued Technical Information Document 14844, "Calculation of Distance Factor for Power and Test Reactors". In this document, a release of fission from the core of a light water reactor into the containment atmosphere was postulated for the purpose of calculating off-site doses in accordance with 10 CFR part 100.
Download or read book Revised Accident Source Terms for Light water Reactors written by and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents revised accident source terms for light-water reactors incorporating the severe accident research insights gained in this area over the last 15 years. Current LWR reactor accident source terms used for licensing date from 1962 and are contained in Regulatory Guides 1.3 and 1.4. These specify that 100% of the core inventory of noble gases and 25% of the iodine fission products are assumed to be instantaneously available for release from the containment. The chemical form of the iodine fission products is also assumed to be predominantly elemental iodine. These assumptions have strongly affected present nuclear air cleaning requirements by emphasizing rapid actuation of spray systems and filtration systems optimized to retain elemental iodine. A proposed revision of reactor accident source terms and some im implications for nuclear air cleaning requirements was presented at the 22nd DOE/NRC Nuclear Air Cleaning Conference. A draft report was issued by the NRC for comment in July 1992. Extensive comments were received, with the most significant comments involving (a) release fractions for both volatile and non-volatile species in the early in-vessel release phase, (b) gap release fractions of the noble gases, iodine and cesium, and (c) the timing and duration for the release phases. The final source term report is expected to be issued in late 1994. Although the revised source terms are intended primarily for future plants, current nuclear power plants may request use of revised accident source term insights as well in licensing. This paper emphasizes additional information obtained since the 22nd Conference, including studies on fission product removal mechanisms, results obtained from improved severe accident code calculations and resolution of major comments, and their impact upon the revised accident source terms. Revised accident source terms for both BWRS and PWRS are presented.
Download or read book Accident Source Terms for Light Water Nuclear Power Plants Final Report written by and published by . This book was released on 1995 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1962 tile US Atomic Energy Commission published TID-14844, C̀̀alculation of Distance Factors for Power and Test Reactors̀̀ which specified a release of fission products from the core to the reactor containment for a postulated accident involving s̀̀ubstantial meltdown of the core.̀̀ This s̀̀ource term, ̀̀ tile basis for tile NRCs̀ Regulatory Guides 1.3 and 1.4, has been used to determine compliance with tile NRCs̀ reactor site criteria, 10 CFR Part 100, and to evaluate other important plant performance requirements. During the past 30 years substantial additional information on fission product releases has been developed based on significant severe accident research. This document utilizes this research by providing more realistic estimates of the s̀̀ource term ̀̀release into containment, in terms of timing, nuclide types, quantities and chemical form, given a severe core-melt accident. This revised s̀̀ource term ̀̀is to be applied to the design of future light water reactors (LWRs). Current LWR licensees may voluntarily propose applications based upon it.
Download or read book Transactions of the American Nuclear Society written by and published by . This book was released on 1996 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NUREG CR written by U.S. Nuclear Regulatory Commission and published by . This book was released on 1977 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Science Technology Index written by and published by . This book was released on 1996 with total page 1704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radioactive Gaseous Effluent Source Terms for Postulated Accident Conditions in Light water cooled Nuclear Power Plants written by W. L. Slagle and published by . This book was released on 1978 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Station Blackout Accidents for the Bellefonte Pressurized Water Reactor written by R. D. Gasser and published by . This book was released on 1986 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accident Source Terms for Light water Nuclear Power Plants written by and published by . This book was released on 1995 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Revised Accident Source Terms for Light water Nuclear Power Plants written by U.S. Nuclear Regulatory Commission. Office of the Secretary and published by . This book was released on 1992 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Power Reactor Events written by and published by . This book was released on 1985 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accident Source Terms for Light water Nuclear Power Plants written by and published by . This book was released on 1992 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Information Abstracts written by and published by . This book was released on 1991 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:
