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Hideo Nakamura - One of the best experts on this subject based on the ideXlab platform.
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Effects of Secondary Depressurization on Core Cooling in PWR Vessel Bottom Small Break LOCA Experiments with HPI Failure and Gas Inflow
Journal of Nuclear Science and Technology, 2006Co-Authors: Mitsuhiro Suzuki, Takeshi Takeda, Hideaki Asaka, Hideo NakamuraAbstract:The effects of steam generator(SG) secondary depressurization, as one of accident management measures during a beyond-design-basis loss-of-coolant accident(LOCA) at pressurized water reactor(PWR), are experimentally investigated at the Large Scale Test Facility(LSTF) which simulates a 4-loop PWR by full-height and 1/48 volumetric scaling. Multiple instrument-tube break at the reactor vessel bottom, equivalent to 0.2% cold leg break, was simulated in the experiments with high pressure injection(HPI) system failure and non-condensable gas inflow from the accumulator injection system(AIS). The experiments showed that secondary depressurization to achieve primary system Cooling at a rate of −55 K/h was sufficient to achieve Core Cooling by the low pressure injection(LPI) system when the gas inflow was prevented, while it was insufficient for Core Cooling in case of the gas inflow. The rapid secondary depres- surization, however, was successful to achieve Core Cooling by the LPI actuation irrespective of the A...
Paul Husby - One of the best experts on this subject based on the ideXlab platform.
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Surface Cooling versus Core Cooling: comparative studies of microvascular fluid- and protein-shifts in a porcine model.
Resuscitation, 2008Co-Authors: Stig Morten Hammersborg, Hege Kristin Brekke, Oddbjørn Haugen, Marit Farstad, Paul HusbyAbstract:Summary Objective To describe how surface Cooling compared with Core Cooling influences fluid and protein distribution, vascular capacity and hemodynamic variables. Methods 14 anesthetized piglets were, following 60min normothermic stabilization, randomly cooled by surface Cooling (ice-sludge) ( n =7) or Core Cooling (endovascular Cooling) ( n =7) to about 28°C. Fluid balance, hemodynamic variables, colloid osmotic pressures (plasma/interstitial fluid), hematocrit, serum-albumin and -protein concentrations, intracranial pressure (ICP) and cerebral metabolic markers of ischemia were measured. Fluid shifts and changes in albumin and protein masses were calculated. At the end total tissue water content was assessed and compared with a normothermic control group. Results Both Cooling modes induced an increase in fluid extravasation rate from 33.9 (31.9) and 27.8 (28.0) to 109.0 (16.5) ( P =0.006) and 95.6 (29.1)ml/kg/min×10 −3 ( P =0.024) in the surface-cooled and Core-cooled groups, respectively. Albumin extravasation was reflected by a significant drop in the albumin mass from 148.8 (11.7) to 111.4 (10.3) ( P =0.000) and from 163.4 (27.8) to 136.8 (19.0)g/kg×10 −2 ( P =0.001) in the surface-cooled and Core-cooled animals, respectively. Similar findings were obtained concerning serum-protein masses. The total tissue water content increased in most organs including brain in both study groups compared with a control. ICP and cerebral metabolic markers remained normal in both groups. Conclusion Rapid lowering of body Core temperature results in extravasation of water and proteins. The amount of extravated fluid and proteins is similar either Cooling is a result of surface Cooling or Core Cooling. Cold-induced fluid extravasation is associated with edema in most tissues including brain.
Gholamreza Jahanfarnia - One of the best experts on this subject based on the ideXlab platform.
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small break loca analysis without emergency Core Cooling systems using the relap5 scdap code in vver 1000 reactor
Annals of Nuclear Energy, 2016Co-Authors: Mohsen Amini Salehi, Gholamreza JahanfarniaAbstract:Abstract In this study, the loss of coolant accident analysis without emergency Core Cooling system on in-vessel Core melt progression is evaluated under a severe accident scenario in Bushehr VVER-1000 reactor. Using the RELAP5/SCDAP mod3.4 computer code, a best estimate simulation event of a 25 mm break SBLOCA, without ECCs is conducted until the reactor pressure vessel failure. In the performed analysis some important parameters such as the amount of hydrogen production, debris bed height and failure of lower plenum due to creep rupture are considered which are not included in the reactor FSAR. It has been concluded that, during the small breaks LOCA without emergency Core Cooling systems, the reactor Core is uncovered at 7430 s; consequently the initial relocation to the LP is occurred at 8130 s. Based on the performed analysis the failure of the lower plenum is estimated in 9170 s due to the creep rupture.
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Small break LOCA analysis without emergency Core Cooling systems using the RELAP5/SCDAP code in VVER-1000 reactor
Annals of Nuclear Energy, 2016Co-Authors: Mohsen Amini Salehi, Gholamreza JahanfarniaAbstract:Abstract In this study, the loss of coolant accident analysis without emergency Core Cooling system on in-vessel Core melt progression is evaluated under a severe accident scenario in Bushehr VVER-1000 reactor. Using the RELAP5/SCDAP mod3.4 computer code, a best estimate simulation event of a 25 mm break SBLOCA, without ECCs is conducted until the reactor pressure vessel failure. In the performed analysis some important parameters such as the amount of hydrogen production, debris bed height and failure of lower plenum due to creep rupture are considered which are not included in the reactor FSAR. It has been concluded that, during the small breaks LOCA without emergency Core Cooling systems, the reactor Core is uncovered at 7430 s; consequently the initial relocation to the LP is occurred at 8130 s. Based on the performed analysis the failure of the lower plenum is estimated in 9170 s due to the creep rupture.
Mitsuhiro Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Effects of Secondary Depressurization on Core Cooling in PWR Vessel Bottom Small Break LOCA Experiments with HPI Failure and Gas Inflow
Journal of Nuclear Science and Technology, 2006Co-Authors: Mitsuhiro Suzuki, Takeshi Takeda, Hideaki Asaka, Hideo NakamuraAbstract:The effects of steam generator(SG) secondary depressurization, as one of accident management measures during a beyond-design-basis loss-of-coolant accident(LOCA) at pressurized water reactor(PWR), are experimentally investigated at the Large Scale Test Facility(LSTF) which simulates a 4-loop PWR by full-height and 1/48 volumetric scaling. Multiple instrument-tube break at the reactor vessel bottom, equivalent to 0.2% cold leg break, was simulated in the experiments with high pressure injection(HPI) system failure and non-condensable gas inflow from the accumulator injection system(AIS). The experiments showed that secondary depressurization to achieve primary system Cooling at a rate of −55 K/h was sufficient to achieve Core Cooling by the low pressure injection(LPI) system when the gas inflow was prevented, while it was insufficient for Core Cooling in case of the gas inflow. The rapid secondary depres- surization, however, was successful to achieve Core Cooling by the LPI actuation irrespective of the A...
G. Ézsöl - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the adequacy of emergency Core Cooling in WWER-440-type reactors
Experimental Thermal and Fluid Science, 1991Co-Authors: L. Szabados, L. Perneczky, G. ÉzsölAbstract:Abstract The analysis of postulated accidents in nuclear power plants is carried out by computer codes that must be validated by experimental results. Experiments were performed on the PMK-NVH facility, a scaled-down model of the primary circuit of the Paks nuclear power plant equipped with WWER-440 reactors. This work presents the results of three experiments with a cold-leg break modeling a 7.4% break in the plant starting from nominal operating conditions with different emergency Core Cooling systems in action. As examples, some results of code validation are presented. The adequacy of the emergency Core Cooling systems is evaluated.