Analysis of hydrogen and dust explosion after vacuum vessel rupture: Preliminary safety analysis of Korean fusion demonstration reactor using MELCOR

Moon, Sung Bo; Lim, Soo Min; Bang, In Cheol

doi:10.1002/er.3793

Cited by 7 publications

(6 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In turbulent flow, the components of the turbulent stress tensor τ t is defined as −ρu 0 i u 0 j . According to Boussinesq's approximation, an analogy between laminar stresses and Reynolds stresses is postulated as Equation (1). The turbulent kinetic energy k is defined as Equation (2).…”

Section: Turbulence Modelmentioning

confidence: 99%

See 1 more Smart Citation

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

2020

View full text Add to dashboard Cite

Summary During hypothetical severe accidents in nuclear power plants, a large amount of hydrogen is generated rapidly as a result of zirconium‐water reaction and released into local compartments. Deflagration or detonation risk is probably caused by the uneven hydrogen distribution. Generally, buoyancy drives light combustible gas up to establish gas stratification. On the other hand, stratification may be destroyed by convection flow from steam injection due to coolant's discharge from the primary loop. The mechanism of erosion of stratification can be divided into buoyancy dominated and momentum dominated regimes, the priority of which depends on a nondimensional parameter, named of interaction Froude number. However, jet velocity and the diameter on the interface between steam and stratification are difficult to measure in experiments. Therefore, CFD method is adopted to capture a detailed velocity profile to solve this problem. In this article, a CFD model of single local compartment facility is built and helium distribution behavior within the local compartment is fully investigated, as a substitute of hydrogen, which is usually used in experiments. Prior to determining the interaction Froude number, four flow models, including laminar flow model, algebraic model, k‐ε turbulence model and shear stress transport (SST) k‐ω model are evaluated under three typical experimental stages, including light gas injection, the formation of stratification, and the erosion of stratification. Results show that SST k‐ω model can predict much better under these specific conditions in the small‐scaled configuration, compared to the experimental results. Next, with the setup of a helium stratification structure with homogeneous layer and gradient layer, the interaction between steam and gradient layer is analyzed in detail. The mechanisms of erosion of stratification can be divided into complete penetration, destruction from the bottom level to the top and soft dissolution without penetration, corresponding to the interaction Froude numbers of being greater than 1, close to 1, and far less than 1. The simulation results are consistent with relevant literature findings. The present work can help studying the complex hydrogen distribution process in local compartment and provide data for evaluation of postinerting strategy in severe accident management.

show abstract

Section: Turbulence Modelmentioning

confidence: 99%

“…Hydrogen risk is a common issue for both nuclear industry [1][2][3] and conventional source of energy. 4,5 In the field of hydrogen storage and hydrogen-powered fuel cell, there occurred many accidents ,6,7 especially the two severe hydrogen explosions occurred in South Korea 8 and Sweden 9 recently.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

2020

View full text Add to dashboard Cite

show abstract

“…Hydrogen risk is one of the key concerns in both nuclear fusion and fission reactors under severe accident conditions. 1 Generally, hydrogen is accompanied by a large amount of steam eruption and flows upward under the effect of buoyancy, forming a buoyant jet. 2 Gas mixtures are transported upwards with steam condensation and the stratification appears in the upper of the containment or vacuum vessel.…”

Section: Introductionmentioning

confidence: 99%

Analytical investigation of hydrogen distribution with steam condensation in confined vessel

Jiang

Tong

et al. 2022

Intl J of Energy Research

View full text Add to dashboard Cite

Summary A one‐dimensional model was developed to predict the hydrogen distribution in a confined vessel with steam condensation. The model consists of two parts, one for the calculation of buoyant jet motion characteristics and the other for the hydrogen volume fraction prediction. First, a set of partial differential equations that can calculate the velocity, characteristic length, and condensation volume fraction at different heights of the jet centerline was established to represent the effect of buoyant jet and steam condensation on hydrogen distribution. Subsequently, the hydrogen distribution model based on buoyancy and Froude number was modified by introducing Reynolds number and condensation volume fraction, and expression of dimensionless buoyancy η was obtained by fitting with Shanghai Jiao Tong University (SJTU) gas mixtures injection experiment. Velocity data obtained from the steam injection test conducted by NASA was used to verify the first part, and the relative error of axis velocity is less than ±20%. SJTU experimental data and TOSQAN experimental data were used to verify the proposed model, the calculated volume fraction is in good agreement with experimental data with the maximum error of less than ±30%, which means that the model can be used to predict the hydrogen distribution in the containment above the break location with the condition of steam condensation.

show abstract

“…Li 11 used MELCOR code to simulate a severe accident at a 1000‐MW PWR, analyzed the influence of three conditions on a station blackout, and compared the results. Moon 12 used MELCOR to conduct hydrogen safety studies on the reactor as the reactor hydrogen explosion damaged the integrity of the containment and resulting in a large amount of radionuclide leakage. Previous studies have focused primarily on the stability and thermal‐hydraulic analysis of marine reactors.…”

Section: Introductionmentioning

confidence: 99%

Effect analysis of break size on source term release and radioactive consequences of marine nuclear reactor during loss of coolant accident

Zhao

Zou²,

et al. 2022

Intl J of Energy Research

View full text Add to dashboard Cite

Summary A simulation calculation model in the case of a severe accident such as a loss of coolant accident (LOCA) was established and calculated by MELCOR code in a marine pressurized water reactor. The effects of severe accidents on the hydrogen source term, release of the radionuclide source term, and the accident process were investigated, and the radiation consequences were analyzed. LOCA sensitivity analysis was conducted with different break sizes; the release and diffusion of source terms were analyzed. The results indicated that the hydrogen yield in the reactor core was dependent on the temperature, and on the residual water in the reactor core, which has no direct relationship with the break size. The break size directly affected the accident progression. However, when the break exceeded a certain size, it did not affect the LOCA process. The break size may not change to change the release amount and migration rule of radionuclides such as Xe and I, and the fission product CsI, as final containment is in dynamic equilibrium in LOCA conditions. The contents of fission products released into the containment vessel, major loop, cavity, and the environment are sensitive to the break size. However, no special correlation is observed between the amount released and the break size. Highlights The hydrogen yield in the reactor core was dependent on the temperature, and on the residual water in the reactor core, which has no direct relationship with the break size. The break size may not change to change the release amount and migration rule of radionuclides such as Xe, I, and CsI, as final containment is in dynamic equilibrium in LOCA conditions. No particular correlation is observed between the amount of radionuclide released and the break size.

show abstract

Analysis of hydrogen and dust explosion after vacuum vessel rupture: Preliminary safety analysis of Korean fusion demonstration reactor using MELCOR

Cited by 7 publications

References 14 publications

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

Analytical investigation of hydrogen distribution with steam condensation in confined vessel

Effect analysis of break size on source term release and radioactive consequences of marine nuclear reactor during loss of coolant accident

Contact Info

Product

Resources

About