A simple mass and heat balance model for estimating plant conditions during the Fukushima Dai-ichi NPP accident
24 Jul 2012-Journal of Nuclear Science and Technology (Taylor & Francis)-Vol. 49, Iss: 8, pp 768-781
TL;DR: A simple evaluation method for the analysis of thermal-hydraulic transients in reactor pressure vessel (RPV) and primary containment vessel (PCV) is proposed to support understanding the accident in this paper.
Abstract: A simple evaluation method for the analysis of thermal-hydraulic transients in reactor pressure vessel (RPV) and primary containment vessel (PCV) is proposed to support understanding the accident b...
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TL;DR: In this article, the emission spectra of zirconium metal in air obtained for a normal-pulse laser (6 ns) and a longpulse (100 ns) (wavelength: 1064nm, pulse energy: 12.5mJ, spot diameter: 0.35mm) were compared to investigate the fundamental aspects of fiber-optic LIBS with the long-Pulse laser.
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21 Apr 2021
TL;DR: In this article, the authors proposed a remote detection method for the decommissioning of the Fukushima Daiichi Nuclear Power Plant (FDNPP), which combines robot and measurement technique.
Abstract: In the decommissioning of the Fukushima Daiichi Nuclear Power Plant (FDNPP), the Japanese government has drawn mid- and long-term roadmap towards 1F decommissioning. However, the decommissioning work of the three reactors has faced difficulties due to the lack of realistic information about the damaged cores such as distribution of fuel debris. Since the radiation levels inside the reactor buildings have been too high for human access, remote detection, which combines robot and measurement technique, is required. In this study, we proposed a remote controlling method. The experiment has been conducted remotely controlling the ultrasonic measurement. Finally, the experiment data and results are successfully obtained through remote control.
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TL;DR: In this article, the effects of spacer grids on the single-phase convection heat transfer enhancement were investigated, and it was found that a second-stage augmentation occurs under wet grid conditions at a distance of 10 diameters downstream of the grid.
Abstract: In the field of thermal hydraulics, substantial progress has been made in research on single and two-phase heat transfer. Grid-enhanced convection heat transfer has been studied [1,2]. Moon et al. [1] performed an experimental study in a 6 × 6 rod bundle to investigate the effects of spacer grids on the single-phase convection heat transfer enhancement. The experimental data showed that the Reynolds number has a significant impact on the heat transfer enhancement only when the Reynolds numbers are lower than about 10,000. They suggested more systematic experiments should be performed using various spacer rids with large blockage ratios at low Reynolds numbers, considering an early phase of the re-flood conditions.Miller et al. [2] reported a two-phase dispersed droplet flow investigation of the grid-enhanced heat transfer augmentation using a 7 × 7 rod bundle heat transfer facility. It was found that a second-stage augmentation occurs under wet grid conditions at a distance of 10 diameters downstream of the grid. This second-stage augmentation was not observed under dry-grid conditions, nor was it observed in single-phase steam cooling tests [2]. Schlegel et al. [3] performed extensive experiments in pipes with diameters up to 0.304 m to collect area-averaged void fraction data using electrical impedance void meters for the purpose of remedying an inability of current drift-flux models to accurately predict the void fraction in churn-turbulent flows in large diameter pipes. They obtained a distribution parameter modified for churn-turbulent flows. It has been evaluated through comparison of the void fraction predicted by the drift-flux model and the measured void fraction. Experimental data bases are important for models’ assessment and verification. Heat transfer and flow experiments using a mercury flow system were carried out by Kinoshita et al. [4] to clarify the validity and predictability of existing experimental correlations. They obtained a result that the heat transfer coefficients agreed well with the Subbotin correlation and analytical results with the STAR-CD code. Conner et al. [5] reported hydraulic benchmark data on Westinghouse PWR mixing vane grids at Texas A&M University. The data acquisition of interest is from an advanced particle image velocimetry (PIV) technique which can attain the high spatial and temporal resolution of the velocity vectors. The data obtained provided amuchmore thorough benchmark of computational fluid dynamics (CFD) results than were available before. Use of this data can not only help in benchmarking steady-state CFD simulations, but can also be used in benchmarking transient CFD simulations such as large eddy simulation [5]. To assess the safety at nuclear facilities and to respond to emergencies against accidental or intentional release of radioactive materials, a LOcal-scale Highresolution atmospheric DIspersion Model using LargeEddy simulation (LOHDIM-LES) has been developed by Nakayama et al. [6]. It was extended to turbulent flows and plume dispersion in various building arrays, and successfully simulated the unsteady behaviors of turbulent flows and plume dispersion in urban-type surface geometries. The CUPID code and TAPINS code were also developed for the analyses of transient twophase flows in nuclear reactor components and transient analysis of an integral reactor, REX-10 [7,8]. Lee and Park [8] compared the calculation results of TAPINS with the experimental data obtained from a series of integral effects tests using a scaled apparatus of REX-10. It was concluded that TAPINS can provide the reasonable prediction on the thermal-hydraulic responses of REX-10 during the transient and accident conditions [8].Moreover, Onder andLeung [9] evaluated the ASSERT-PV subchannel code using boiling-lengthaverage (BLA) critical heat flux (CHF) values for the CANFLEX bundle at cross-sectional average subcooled conditions. Severe accident analyses are also carried out. Kawahara et al. [10] proposed a method for identifying the success criteria regarding alternative water injection in long-term station blackout (SBO) of a BWR5 model plant by summarizing the sensitivity analysis results using RELAP5/SCDAP mod 3.5. They found that preventing core damage was almost equivalent to
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References
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01 Jan 2011
6,700 citations
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...Radiation: Stefan–Boltzmann q 00 1⁄4 eradsSB T4sf T4c [5]...
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TL;DR: In this paper, an analytical expression for the heat-transfer coefficient near the minimum in film pool boiling from a horizontal surface was derived, based on a simplified geometrical model.
Abstract: Taylor-Helmholtz Hydrodynamic Instability and its significance with regard to film boiling heat transfer from a horizontal surface is discussed. It is shown that near the minimum film-boiling heat flux, the bubble spacing and growth rate is determined by Taylor Instability neglecting the effect of fluid depth and viscosity. Utilizing a simplified geometrical model, an analytical expression for the heat-transfer coefficient near the minimum in film pool boiling from a honizontal surface was derived. Combining this equation with the available correlation for the minimum heat flux yields an analytical equation for the temperature difference at the minimum, which defines the location of the minimum point. The above equations agree with the available experimental measurements made on n-pentane and carbon tetracliloride within plus or minus 10 per cent. (auth)
582 citations
01 Jan 1992
Abstract: A Heat Transfer in Condensation.- 1 Fundamentals.- 2 Film Condensation of Stagnant Vapors.- 3 Drop Condensation of Stagnant Vapors.- 4 Condensation of Flowing Vapors.- 5 Condensation of Metal Vapors.- 6 Condensation of Vapors of Miscible Liquids.- 7 Condensation of Vapors of Immiscible Liquids.- 8 Enhancement of Heat Transfer During Condensation.- B Heat Transfer in Boiling.- 9 The Different Types of Heat Transfer During Boiling.- 10 Physical Fundamentals of Vapor Bubble Formation.- 11 Heat Transfer During Boiling of Pure Substances in Free Convection.- 12 Heat Transfer in Falling Film Evaporators.- 13 Heat Transfer During Boiling of Pure Substances in Forced Flow.- 14 Heat Transfer During Boiling of Mixtures in Free Convection.- 15 Heat Transfer During Boiling of Mixtures in Forced Flow.- 16 Enhancement of Heat Transfer During Boiling.- Index of Names.
435 citations