Assessment of MELCOR condensation models with the presence of noncondensable gas in natural convection flow regime

Yoon, Dhongik S.; Jo, HangJin; Corradini, Michael L.

doi:10.1016/j.nucengdes.2017.03.018

Cited by 3 publications

(5 citation statements)

References 12 publications

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“…The conclusions that can be drawn from this sensitivity analysis agree with those reported in [23] where the use of a CL value for a vertical plate-type HS equal to its real height was suggested for a good estimation of the condensation rate, also if underpredicted heat transfer coefficients were still reported, although for other HS's geometries no investigations were reported in [23], and a clear advice that the conclusions found may be not valid for other HS's geometries was made.…”

Section: Thermal-hydraulics Sensitivity Analysessupporting

confidence: 89%

“…The authors suggest setting the CL value equal to the physical length of the plate but, at the same time, they underline that this solution cannot be extended a priori to other HS's geometries. Even if a detailed investigation on the "CL value" issue similar to that performed in [23] was not performed in the present work, the use of the outer diameter value for a cylindrical wall with condensation on the outer surface can be suggested for MELCOR. For the ASTEC code, similar problems and explanations were also found in [10], where CL values of about 0.01-0.02 m were suggested, although, in the present analysis, the values of the same order of magnitude provided too strong condensation rates.…”

Section: Characteristic Length Relationsmentioning

confidence: 94%

“…Such discrepancy is due to the film condensation model implemented in both codes, which is not suitable to describe the drop-wise condensation probably occurring on the condenser surfaces. In MELCOR, the issue of CL for a vertically oriented plate type HS was carefully described in [23]. The authors suggest setting the CL value equal to the physical length of the plate but, at the same time, they underline that this solution cannot be extended a priori to other HS's geometries.…”

Section: Characteristic Length Relationsmentioning

confidence: 99%

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Stand-Alone Containment Analysis of the Phébus FPT Tests with the ASTEC and the MELCOR Codes: The FPT-0 Test

Bruno

Paci

2017

Science and Technology of Nuclear Installations

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The integral Phébus tests were probably one of the most important experimental campaigns performed to investigate the progression of severe accidents in light water reactors. In these tests, the degradation of a PWR fuel bundle was investigated employing different control rod materials and burn-up levels in strongly or weakly oxidizing conditions. From the results of such tests, numerical codes such as ASTEC and MELCOR have been developed to describe the evolution of a severe accident. After the termination of the experimental Phébus campaign, these two codes were furthermore expanded. Therefore, the aim of the present work is to reanalyze the first Phébus test (FPT-0) employing the updated ASTEC and MELCOR versions to ensure that the new improvements introduced in such codes allow also a better prediction of these Phébus tests. The analysis focuses on the stand-alone containment aspects of this test, and the paper summarizes the main thermal-hydraulic results and presents different sensitivity analyses carried out on the aerosols and fission products behavior. This paper is part of a series of publications covering the four executed Phébus tests employing a solid PWR fuel bundle: FPT-0, FPT-1, FPT-2, and FPT-3.

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Section: Thermal-hydraulics Sensitivity Analysessupporting

confidence: 89%

Section: Characteristic Length Relationsmentioning

confidence: 94%

Section: Characteristic Length Relationsmentioning

confidence: 99%

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Stand-Alone Containment Analysis of the Phébus FPT Tests with the ASTEC and the MELCOR Codes: The FPT-0 Test

Bruno

Paci

2017

Science and Technology of Nuclear Installations

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“…Similar conclusions were also found for the Phébus FPT-0 test [19] . The important influence of the CL was also stressed in [33] , where a study on the influence of the CL value on the heat transfer and condensation rates for vertically-oriented plate HSs was performed. Even if different walls geometries were considered in the present work (vertical cylinders instead of vertical plates), a connection exists between the two works.…”

Section: Resultsmentioning

confidence: 99%

Stand-alone containment analysis of Phébus FPT tests with ASTEC and MELCOR codes: the FPT-2 test

Bruno

Paci

2018

Heliyon

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During the last 40 years, many studies have been carried out to investigate the different phenomena occurring during a Severe Accident (SA) in a Nuclear Power Plant (NPP). Such efforts have been supported by the execution of different experimental campaigns, and the integral Phébus FP tests were probably some of the most important experiments in this field. In these tests, the degradation of a Pressurized Water Reactor (PWR) fuel bundle was investigated employing different control rod materials and burn-up levels in strongly or weakly oxidizing conditions. From the findings on these and previous tests, numerical codes such as ASTEC and MELCOR have been developed to analyze the evolution of a SA in real NPPs. After the termination of the Phébus FP campaign, these two codes have been furthermore improved to implement the more recent findings coming from different experimental campaigns. Therefore, continuous verification and validation is still necessary to check that the new improvements introduced in such codes allow also a better prediction of these Phébus tests. The aim of the present work is to re-analyze the Phébus FPT-2 test employing the updated ASTEC and MELCOR code versions. The analysis focuses on the stand-alone containment aspects of this test, and three different spatial nodalizations of the containment vessel (CV) have been developed. The paper summarizes the main thermal-hydraulic results and presents different sensitivity analyses carried out on the aerosols and fission products (FP) behavior. When possible, a comparison among the results obtained during this work and by different authors in previous work is also performed. This paper is part of a series of publications covering the four Phébus FP tests using a PWR fuel bundle: FPT-0, FPT-1, FPT-2, and FPT-3, excluding the FPT-4 one, related to the study of the release of low-volatility FP and transuranic elements from a debris bed and a pool of melted fuel.

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“…As the non-condensable gas fraction is large enough, the thermal resistance of liquid film can be neglected (Corradini, 1984;Yoon et al, 2017). Therefore, the total heat transfer coefficient can be simplified as Eq.…”

Section: Fundamentals Of the Modelmentioning

confidence: 99%

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

Wang

Tong

et al. 2021

Front. Energy Res.

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Steam condensation plays a key role in prediction of the pressure behavior and hydrogen distribution in the containment during a hypothetical loss-of-coolant accident or a severe accident in a light water nuclear reactor. The objective of this study is to evaluate and improve the condensation model in GASFLOW code. Reynolds analogy coupled with wall function and Chilton-Colburn empirical analogy is used to model heat and mass transfer in GASFLOW, which has requirements for dimensional distance of the first cell near the wall and some deficiencies in description of heat and mass transfer process in the stagnant zone. Based on the evaluation of original condensation, the results shows good agreement with COPAIN experiment cases where the mass fraction of air ranges from 76.7 to 86.4%. However, with the changes in geometry of the facility and the presence of helium, the original model has a large deviation in the prediction of pressure, temperature and gas distribution compared with MISTRA ISP47 (OECD International Standard Problem No. 47) experiment data. This work proposes a modified condensation model which uses McAdams correlation and Schlichting correlation with a weight factor to calculate natural, forced, or mixed convection heat transfer coefficient, and adopts Chilton-Colburn empirical analogy to model mass transfer. The modified model has no requirement for the dimensionless distance near the wall in heat and mass transfer calculation and improves the prediction performance of heat transfer in stagnant zone. The prediction result of the modified model shows good agreements with MISTRA ISP47 problem, and the error of it compared with COPAIN experiment data is within 25% which is the same as that predicted by the original model.

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Assessment of MELCOR condensation models with the presence of noncondensable gas in natural convection flow regime

Cited by 3 publications

References 12 publications

Stand-Alone Containment Analysis of the Phébus FPT Tests with the ASTEC and the MELCOR Codes: The FPT-0 Test

Stand-Alone Containment Analysis of the Phébus FPT Tests with the ASTEC and the MELCOR Codes: The FPT-0 Test

Stand-alone containment analysis of Phébus FPT tests with ASTEC and MELCOR codes: the FPT-2 test

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

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