Fuel fragmentation and relocation (FFR) model in SPACE code PART 2: Validation and sensitivity analyses.

• To validate the newly implemented FFR model in the SPACE code, the Halden IFA-650 test is calculated. • Overall prediction with the FFR model in SPACE is well matched with experimental results. • For some tests, the best estimated clad deformation model is necessary to validate the FFR model better. • Sensitivity analyses are conducted for fragmentation, packing fraction, and threshold gap to better understand the FFR model in SPACE. The new ECCS regulations were recently considered in South Korea. One of the major concerns in this revision is the consideration of fuel fragmentation, relocation, and dispersal (FFRD) phenomena during a loss of coolant accident (LOCA). In response, the FFR model was newly implemented in the SPACE code, which is a safety analysis code. The FFR model based on the QT model, which was developed by Quantum Technology Corporation, was developed with a threshold size of fuel fragments for fuel relocation, fuel power distribution, and so on. In this study, to validate the newly developed FFR model in SPACE code, calculations using Halden IFA-650 tests are conducted. Overall, the results show that the newly developed FFR model yields results that are consistent with experimental results in terms of fuel relocation and their effects on cladding temperature. However, when the cladding deformation is not well predicted, the fuel relocation prediction is poor. Thus, the cladding deformation is the most critical parameter for the FFR phenomena. In addition, for a fresh fuel condition, the threshold fragment size is additionally proposed in the fuel relocation model. For a better understanding of the FFR model behavior during a LOCA, some sensitivity tests for major FFR model parameters are conducted. This can give valuable information to develop FFR modeling in safety analysis methodology. [ABSTRACT FROM AUTHOR]