| Popis: |
The RELAP4/MOD6 code has been used extensively in the UK for the evaluation of the thermal-hydraulics following a large Loss of Coolant Accident (LOCA) in a Pressurised Water Reactor. The studies have included both assessment of Sizewell ‘B’ safety case calculations and comparisons of the code with data from integral test facilities. RELAP4/MOD6 has considerable user flexibility by allowing the specification through input of a variety of heat transfer/hydraulic options. Recommended options have been identified by the code developers based on the application of the code to a wide range of test facilities, both integral and separate-effects. In this paper, NNC have applied the code to a number of large scale tests in the FLECHT-SEASET facility. This facility simulates a complete PWR fuel assembly and provides reflood heat transfer data for forced flooding, low pressure conditions. The application of the code with the recommended heat transfer options led to poor agreement with the data especially for axial locations along the rod away from the location of peak clad temperature. A revised set of options led to much better overall agreement with the data. Further development and validation of the code is recommended, however, especially in the area of entrainment modelling. |
