Review of thermal-hydraulic researches in severe accidents in light water reactors

Kataoka, Isao

doi:10.1080/00223131.2013.750797

Cited by 12 publications

(4 citation statements)

References 69 publications

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“…Therefore, V/V can be estimated to be around 1.9%, and the overall uncertainty of density measurement ( ρ/ρ) is estimated to be about 2%. Equation (2) indicates that the uncertainty in surface tension measurement is mainly determined by those of ρ, r 0 , and ω c . As described earlier, the uncertainties of ρ and r 0 are 2% and 0.63%, respectively.…”

Section: Density Viscosity and Surface Tension Measurementmentioning

confidence: 99%

“…In order to investigate the progression of an accident, understanding the behavior of molten core materials is an urgent issue. The progression of severe accidents in light-water reactors can be analyzed using system codes such as MELCOR, MAAP, and SAMPSON [2]. These codes use empirical equations and parameters that are based on the results of simulated experiments.…”

Section: Introductionmentioning

confidence: 99%

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Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

Ohishi

Muta

Kurosaki

et al. 2016

Journal of Nuclear Science and Technology

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In order to investigate the progression of a core meltdown accident, it is necessary to understand the behavior of molten core materials. Zr-Fe alloys are one of the low-melting-temperature liquid phases that are thought to form in the early stages of bundle degradation. The objective of this study is to measure the thermophysical properties of Zr-Fe liquid alloys. Alloy samples with a composition of Zr 1−x Fe x (x = 0.12, 0.24, and 0.50) were synthesized by arc melting, and their density, viscosity, and surface tension were measured using an electrostatic levitation technique. The results indicate that the density of Zr-Fe liquid alloys can be estimated by a linear combination of the measured or extrapolated densities of pure Zr and Fe. The viscosities of the Zr-Fe liquid alloys can be roughly estimated by extrapolating those of Zr to lower temperatures, although this method tends to underestimate the viscosity of alloys, especially for eutectic compositions. The values of the Zr-Fe liquid alloys' surface tensions are close to those of pure Zr.

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Section: Density Viscosity and Surface Tension Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

Ohishi

Muta

Kurosaki

et al. 2016

Journal of Nuclear Science and Technology

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“…However, in this instance, AC power had not been restored after this interval, nor could an alternative injection to the reactor (after depressurization of the RPV) be established, inevitably resulting in core damage in Units 2 and 3. According to Tanabe [27] and Kataoka [28], core damage started to occur after 2, 5, and 2.5 hours after the loss of emergency core cooling capabilities in the case of Units 1, 2, and 3, respectively.…”

Section: Prolonged Loss Of Ac Powermentioning

confidence: 99%

Insights on Accident Information and System Operations during Fukushima Events

Kim

2014

Science and Technology of Nuclear Installations

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As part of the development of an integrated perspective on lessons learned from the Fukushima Daiichi nuclear accident, this paper highlights lessons learned and implications relating to the accident information and system operational aspects during the events. Our analysis clearly indicates that the plant was neither designed nor prepared to withstand such an unexpected event, which included a complete loss of electrical power sources for a long period. The author focused on the accident information and system operational aspects of the Fukushima event, including lack of information, provision of wrong information, operator performance in life-threatening environments, and improvisation given lack of procedures and training. Suggestions for further improvement of the nuclear plant safety are then made with respect to preparation for beyond design basis events, provision of reliable essential information to operators, development of guidelines/procedures, training of operators, and development of operator support systems with consideration of severe accidents caused by unexpected events. It is hoped that the lessons learned from the accident will significantly contribute to the enhancement of nuclear plant safety.

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“…plant (NPP) accident [Kataoka, 2013]. MELCOR is an integrated, engineering-level computer code used to model the progression of postulated accidents in light water reactors (LWRs) [Gauntt, et al, 2000].…”

Section: Icone22-30011mentioning

confidence: 99%

Estimation of Source Term Uncertainty in a Severe Accident With Correlated Variables

Zheng

Itoh

Tamaki

et al. 2014

Volume 6: Nuclear Education, Public Acceptance and Related Issues; Instrumentation and Controls (I&C); Fusion Engineering;

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The quantitative evaluation of the fission product release to the environment during a severe accident is of great importance. In the present analysis, integral severe accident code MELCOR 1.8.5 has been applied to estimating uncertainty of source term for the accident at Unit 2 of the Fukushima Daiichi nuclear power plant (NPP) as an example and to discussing important models or parameters influential to the source term. Forty-two parameters associated with models for the transportation of radioactive materials were chosen and narrowed down to 18 through a set of screening analysis. These 18 parameters in addition to 9 parameters relevant to in-vessel melt progression obtained by the preceding uncertainty study were input to the subsequent sensitivity analysis by Morris method. This one-factor-at-a-time approach can preliminarily identify inputs which have important effects on an output, and 17 important parameters were selected from the total of 27 parameters through this approach. The selected parameters have been integrated into uncertainty analysis by means of Latin Hypercube Sampling technique and Iman-Conover method, taking into account correlation between parameters. Cumulative distribution functions of representative source terms were obtained through the present uncertainty analysis assuming the failure of suppression chamber. Correlation coefficients between the outputs and uncertain input parameters have been calculated to identify parameters of great influences on source terms, which include parameters related to models on core components failure, models of aerosol dynamic process and pool scrubbing.

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Review of thermal-hydraulic researches in severe accidents in light water reactors

Cited by 12 publications

References 69 publications

Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

Thermophysical properties of molten core materials: Zr–Fe alloys measured by electrostatic levitation

Insights on Accident Information and System Operations during Fukushima Events

Estimation of Source Term Uncertainty in a Severe Accident With Correlated Variables

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