Research Article
Analysis of the Effect of Severe Accident Scenario on Debris Properties in Lower Plenum of Nordic BWR Using Different Versions of MELCOR Code
Table 1
MELCOR modeling parameters.
| | MELCOR 1.86 [18, 19] | MELCOR 2.1 [20, 21] | MELCOR 2.2 [1, 2] |
| Gap Thickness (m) | 0.075e-3 | 0.0[26] | 0.0[26] |
| Velocity of Falling Debris (m/s) | Default 1.0. 0.1 value was used in MELCOR 1.86 calculations [12, 24]. | 0.01[26] | 0.01[26] |
| Particulate debris porosity (-) | 0.25[34] | 0.4[26] | 0.4[26] |
| Particulate debris equivalent diameter in LP (m) | 0.02 | 0.002[26] | 0.002[26] |
| The max. molten Zr breakout flow rate (SC1141(2)) (kg/m-s) | 1.0 | 0.2 | 0.2 |
| COR-package candling heat transfer coefficient. (W/m2-K) | HFRZUO, HFRZZR, HFRZSS, HFRZZX, HFRZSX, HFRZCP | 1000 | 7500 7500 2500 7500 2500 2500 | 7500 7500 2500 7500 2500 2500 |
| COR package radiative heat transfer parameters (FCELR, FCELA) | 0.25 0.25 | 0.1 0.1 | 0.1 0.1 |
| COR package min. porosity for flow (SC1505(1) – COR package, SC4413(5) – CVH package) and heat transfer SC1505(2) calculations. | 0.001 1.e-6 0.001 | 0.05 0.05 0.05 | 1.e-5[25]. 0.05 0.05 |
| Zircaloy Oxidation Rate Constant Coefficients by Oxygen(SC1001(1-2,2)), (see [18–21] for details) | 50.4 Kg2(Zr)/m4-s 14630.0 K | 26.7 Kg2(Zr)/m4-s 17490.0 K | 26.7 Kg2(Zr)/m4-s 17490.0 K |
| Conduction enhancement for molten components (SC1250(1)) | 3200K | 2800K | 2800K |
| Minimum fraction of the initial volume available to hydrodynamic materials (SC4414) | 0.001 | 0.01 | 0.01 |
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