Loss of residual heat removal system simulation using CATHARE thermal hydraulic code
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Thermal hydraulic CATHARE V1.3U code has been used to simulate an International Standard Problem (ISP38) experiment conducted at BETHSY Integral Test Facility located in Grenoble, France. This experiment dealt with simulation of the loss of Residual Heat Removal System (RHRS) during midloop operation. It involved opening of the pressurizer manway and steam generator outlet plenum manway simultaneously with switching on the heating rods power simulating loss of RHRS. The total power was kept unchanged with the level 138 kW throughout the test. Mass discharge through both manways led to core boiling and uncovery. Test was stopped when the primary cooling system was filled back to a midloop level. Overall, the code's prediction and experimental data were found to be in a reasonable qualitative agreement. However, the code underestimated the time of the core uncovery and the actuation of the gravity feed injection due to the overpredicted mass discharge through steam generator manway during the initial stage of the transient. This was caused by CATHARE's miscalculation of the phase separation effect at the hot leg/surge line tee junction and significant water entrainment into the surge line at the beginning of the test. It was found that the code's model of the upward tee junction needs to be refined for the low pressure ranges.
author list (cited authors)
Troshko, A. A., & Hassan, Y. A.