Pretest predictions of the Fast Flux Test Facility passive safety test phase IIB transients using United States derived computer codes and methods

The SASSYS/SAS4A systems analysis code was used to simulate a series of unprotected loss of flow (ULOF) tests planned at the Fast Flux Test Facility (FFTF). The subject tests were designed to investigate the transient performance of the FFTF during various ULOF scenarios for two different loading patterns designed to produce extremes in the assembly load pad clearance and the direction of the initial assembly bows. The tests are part of an international program designed to extend the existing data base on the performance of liquid metal reactors (LMR). The analyses demonstrate that a wide range of power-to-flow ratios can be reached during the transients and therefore, will yield valuable data on the dynamic character of the structural feedbacks in LMRs. These analyses will be repeated once the actual FFTF core loadings for the tests are available. These predictions similar ones obtained by other international participants in the FFTF program, and post-test analyses will be used to upgrade and further verify the computer codes used to predict the behavior of LMRs. (author)