The Experts below are selected from a list of 894 Experts worldwide ranked by ideXlab platform
Geoff Parks - One of the best experts on this subject based on the ideXlab platform.
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an estimate of the order of magnitude of the explosion during a Core Meltdown compaction accident for heavy liquid metal fast reactors a disquieting result updating the bethe tait model
Progress in Nuclear Energy, 2015Co-Authors: Francisco J Arias, Geoff ParksAbstract:Abstract Criticality and recriticality considerations in heavy liquid metal fast reactors (HLMFRs) after a hypothetical Core Meltdown accident are discussed. Although many aspects of system behaviour in such scenarios can be deduced directly from the classical theory of sodium-cooled fast reactors (SFRs), certain ideas that have been accepted as true for SFRs cannot be extrapolated to HLMFRs without sufficiently careful thought. In this paper, we are concerned, as in SFRs, with fuel compaction, but with one important difference: there would be no boiling of the surrounding heavy liquid metal pool. Utilizing a Bethe–Tait model, it is shown that, due to the power flattening effect of the heavy liquid metal, explosive excursions at least an order of magnitude higher than for SFRs in similar situations are conceivable.
A Hedayat - One of the best experts on this subject based on the ideXlab platform.
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a review on hydrogen generation explosion and mitigation during severe accidents in light water nuclear reactors
International Journal of Hydrogen Energy, 2017Co-Authors: R Gharari, H Kazeminejad, Mataji N Kojouri, A HedayatAbstract:Abstract Progress of severe accident (SA) can be divided into Core degradation and post Core Meltdown. An important phenomena during severe accidents is the hydrogen generation from exothermal reaction between oxidation of Core components, and molten Core concrete interaction (MCCI). During the severe accidents, a large amounts of hydrogen is produced, deflagrated and consequently the containment integrity is violated. Therefore, the main objectives of this study is to highlight the source of hydrogen production during SA. First, a thorough literature review and main sources of hydrogen production, hydrogen reduction systems are introduced and discussed. Based on the available results, the amount of produced hydrogen in a typical pressurized water reactor (PWR) and a boiling water reactor (BWR) are estimated to be 1000 and 4000 kg, respectively during in-vessel phase. The average rate of hydrogen production is about 1 kg/s during reflooding of a degraded Core. Also, about 2000 kg hydrogen is produced during MCCI for a PWR. The lower and upper range of hydrogen required to initiate combustion is 4.1 and 74 vol percent, respectively. In this paper a review is provided of what has been done in the literature with regard to hydrogen generation in severe accidents of nuclear power plants. In addition, the review identifies the literature gaps and underlines the need of developing a systematic hydrogen management strategy. A hydrogen management strategy is proposed in order to maintain the containment integrity against the probable combustion or hydrogen explosion loads.
Francisco J Arias - One of the best experts on this subject based on the ideXlab platform.
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an estimate of the order of magnitude of the explosion during a Core Meltdown compaction accident for heavy liquid metal fast reactors a disquieting result updating the bethe tait model
Progress in Nuclear Energy, 2015Co-Authors: Francisco J Arias, Geoff ParksAbstract:Abstract Criticality and recriticality considerations in heavy liquid metal fast reactors (HLMFRs) after a hypothetical Core Meltdown accident are discussed. Although many aspects of system behaviour in such scenarios can be deduced directly from the classical theory of sodium-cooled fast reactors (SFRs), certain ideas that have been accepted as true for SFRs cannot be extrapolated to HLMFRs without sufficiently careful thought. In this paper, we are concerned, as in SFRs, with fuel compaction, but with one important difference: there would be no boiling of the surrounding heavy liquid metal pool. Utilizing a Bethe–Tait model, it is shown that, due to the power flattening effect of the heavy liquid metal, explosive excursions at least an order of magnitude higher than for SFRs in similar situations are conceivable.
R Gharari - One of the best experts on this subject based on the ideXlab platform.
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a review on hydrogen generation explosion and mitigation during severe accidents in light water nuclear reactors
International Journal of Hydrogen Energy, 2017Co-Authors: R Gharari, H Kazeminejad, Mataji N Kojouri, A HedayatAbstract:Abstract Progress of severe accident (SA) can be divided into Core degradation and post Core Meltdown. An important phenomena during severe accidents is the hydrogen generation from exothermal reaction between oxidation of Core components, and molten Core concrete interaction (MCCI). During the severe accidents, a large amounts of hydrogen is produced, deflagrated and consequently the containment integrity is violated. Therefore, the main objectives of this study is to highlight the source of hydrogen production during SA. First, a thorough literature review and main sources of hydrogen production, hydrogen reduction systems are introduced and discussed. Based on the available results, the amount of produced hydrogen in a typical pressurized water reactor (PWR) and a boiling water reactor (BWR) are estimated to be 1000 and 4000 kg, respectively during in-vessel phase. The average rate of hydrogen production is about 1 kg/s during reflooding of a degraded Core. Also, about 2000 kg hydrogen is produced during MCCI for a PWR. The lower and upper range of hydrogen required to initiate combustion is 4.1 and 74 vol percent, respectively. In this paper a review is provided of what has been done in the literature with regard to hydrogen generation in severe accidents of nuclear power plants. In addition, the review identifies the literature gaps and underlines the need of developing a systematic hydrogen management strategy. A hydrogen management strategy is proposed in order to maintain the containment integrity against the probable combustion or hydrogen explosion loads.
Ph. Marsault - One of the best experts on this subject based on the ideXlab platform.
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Passive Complementary Safety Devices for ASTRID severe accident prevention
HAL CCSD, 2017Co-Authors: Saez M., Lavastre R., Ph. MarsaultAbstract:International audienceSodium-cooled Fast Reactor is one of the Generation IV reactor concepts. It has been selected to secure the nuclear fuel resources and to manage radioactive waste. In this context, the CEA (French Commission for Atomic Energy and Alternative Energy) with its partners is involved in a substantial effort on the ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) Project. ASTRID Core design is mainly guided by safety objectives. The first one is prevention of the Core Meltdown accident, at first through natural favourable behaviour of the Core and of the reactor, and with the addition of passive complementary systems if natural behaviour is not sufficient for some transient cases. The second one is the mitigation of the severe accident to guarantee that Core melting accidents do not lead to significant mechanical energy release. The robust safety demonstration is supported by complementing ASTRID Core with two types of Complementary Safety Devices dedicated to Core damage prevention that would passively shut down the reactor. The first type is based on the Curie point use of electromagnetic devices that hold some specific ASTRID shutdown systems to address unprotected loss of heat sink transients (ULOHS)
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Passive complementary safety devices for astrid severe accident prevention
International Conference on Fast Reactors and Related Fuel Cycles Next Generation Nuclear Systems for Sustainable Development (FR17), 2017Co-Authors: Saez M., Lavastre R., Ph. MarsaultAbstract:International audienceSodium-cooled Fast Reactor is one of the Generation IV reactor concepts. It has been selected to secure the nuclear fuel resources and to manage radioactive waste. In this context, the CEA (French Commission for Atomic Energy and Alternative Energy) with its partners is involved in a substantial effort on the ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) Project.ASTRID Core design is mainly guided by safety objectives. The first one is prevention of the Core Meltdown accident, at first through natural favourable behaviour of the Core and of the reactor, and with the addition of passive complementary systems if natural behaviour is not sufficient for some transient cases. The second one is the mitigation of the severe accident to guarantee that Core melting accidents do not lead to significant mechanical energy release.The robust safety demonstration is supported by complementing ASTRID Core with two types of Complementary Safety Devices dedicated to Core damage prevention that would passively shut down the reactor. The first type is based on the Curie point use of electromagnetic devices that hold some specific ASTRID shutdown systems to address unprotected loss of heat sink transients (ULOHS). The second type is a hydraulically suspended absorber rod subassembly, called RBH, dedicated to unprotected loss of flow (ULOF) transients; under normal operation, the absorber rod subassembly is hydraulically suspended above the Core by the upward flow of the sodium coolant. Should an ULOF event and the associated drop in flow rate occur, this upward force would become insufficient, thus allowing the absorber insertion into the active Core region by gravity.This paper presents a state of the art on simulations of accidental transients using CATHARE2 thermal-hydraulic system code completed by post-processing with TrioMC and CATHARE2/TrioCFD coupling. For ASTRID severe accident prevention, these passive Complementary Safety Devices achieve absence of sodium boiling (ULOF) and limitation of the reactor temperature (ULOHS)