| Title |
Numerical Analysis of Single Phase Thermal Stratification in both Cold Legs and Downcomer by Emergency Core Cooling System Injection : A Study on the Necessity to Consider Buoyancy Force Term |
| Authors |
Gong Hee Lee ; Ae Ju Cheong |
| DOI |
http://dx.doi.org/10.6110/KJACR.2017.29.12.654 |
| Keywords |
부력 ; 전산유체역학 ; 비상노심냉각계통 ; 단상 ; 열성층 Buoyancy force ; Computational fluid dynamics ; Emergency core cooling system ; Single phase ; Thermal stratification |
| Abstract |
When emergency core cooling system (ECCS) is operated during loss of coolant accident (LOCA) in a pressurized water reactor (PWR), pressurized thermal shock (PTS) phenomenon can occur as cooling water is injected into a cold leg, mixed with hot primary coolant, and then entrained into a reactor vessel. Insufficient flow mixing may cause temperature stratification and steam condensation. In addition, flow vibration may cause thermal stresses in surrounding structures. This will reduce the life of the reactor vessel. Due to the importance of PTS phenomenon, in this study, calculation was performed for Test 1 among six types of OECD/NEA ROSA tests with ANSYS CFX R.17. Predicted results were then compared to measured data. Additionally, because temperature difference between the hot coolant at the inlet of the cold leg and the cold cooling water at the inlet of the ECCS injection line is 200 K or more, buoyancy force due to density difference might have significant effect on thermal-hydraulic characteristics of flow. Therefore, in this study, the necessity to include buoyancy force term in governing equations for accurate prediction of single phase thermal stratification in both cold legs and downcomer by ECCS injection was numerically studied. |