|
| Phenomena Class | Associated phenomena | Model implementation description |
|
| Thermal-hydraulic and fuel rod degradation | Stored energy | Total power |
| Decay Heat |
| Zr-steam oxidation parameters | Zr-H2O oxidation multiplier |
|
| Core melt progression | Zr melt breakout temperature | Cladding integrity with oxidation |
| Cladding creep Rupture temperature |
| Fuel rod collapse temperature | Material creep (Larson-Miller) limit |
| Fractional local dissolution of UO2 in molten Zr | Contact area multiplier |
| Core material melt temperatures | Fuel melt temperature |
| Control rod melt temperature |
|
| Melt relocation to lower head | Melt relocation heat transfer coefficient | Flow blockage based on porosity |
| Fuel coolant interaction | Large uncertainties, addressed in separate supplementary analysis |
|
| Oxide/metal separation | (No unique model parameter, a function of oxidation process and relocation) |
|
| Crust formation and failure | Gap heat transfer | Conservatively neglected |
|
| In-vessel debris formation | Heat transfer within fuel debris beds | Particulate debris size and debris porosity in lower plenum |
|
| Ex-reactor vessel cooling | Heat transfer rate | Heat transfer coefficient multiplier |
| Material properties |
| CHF on lower plenum surface |
|
| RPV failure modes | Local and global lower head/vessel failure | Initial radius of the local vessel failure |
| Lower head damage fraction for failure |
| Corium friction coefficient (in contact with vessel following failure) |
| Thermal radiation exchange | Emissivities |
|
| MCCI | | Downward heat transfer coefficient |
| MCCI integrity of ex-vessel protective structure | Side wall heat transfer coefficient |
| Flat plate CHF Kutateladze number (multiplier) |
|
| Melt spreading | Design dependent |
|
| Steam/hydrogen transport | Containment transition to single convective volume | Flow area between containment compartments |
|
| Hydrogen recombination | PAR efficiency | Rate of recombination |
| Operation cutoff based on H2 concentration |
|
| Hydrogen combustion | Autoignition temperature | Local/global |
|
| Long-term containment heat removal | Design dependent |
|
| Fission product transport | Flow area between containment compartments |
|
