Evaluation report on CCTF Core-I reflood tests C1-5 (Run 14), C1-7 (Run 16) and C1-14 (Run 23)

The present report describes the effects of the initial clad temperature on the reflood phenomena observed in the Cylindrical Core Test Facility (CCTF) at Japan Atomic Energy Research Institute. The evaluation is based on the data of tests C1-5, C1-7 and C1-14 of the CCTF-Core I test series. Nominal initial peak clad temperatures in these tests are 6000C, 7000C and 8000C, respectively. With the higher initial clad temperature, the higher loop mass flow rate and the lower water accumulation in the core and the upper plenum were obtained in an early reflood transient. However, the core inlet flow conditions, which is sensitive to the core cooling, were not much affected by the higher initial clad temperature. The slower quench front propagation was observed with the higher initial clad temperature. However, the heat transfer coefficient was almost identical with each other before the turnaround time, which resulted in the lower temperature rise with the highest initial clad temperature. This qualitatively agreed with the results of the forced feed FLECHT experiment. (author)