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Abstract
The applicability of the REFLA/TRAC code, which is one of best-estimate codes based on two-fluid model, was assessed for a typical small-break 103s-of-coolant accident (SBLOCA) transient of PWR. The main assessment subject was to investigate whether the physical models in REFLA/TRAC can apply to the transient under SBLOCA condition (high pressure/low flow rate) or not. The applicability had been verified under low pressure/low flow rate condition during reflood phase in large-break LOCA transients of PWR. The assessment calculation was performed for Run SB-CL-05 (5% cold leg break SBLOCA test) in the ROSA-IV large-scale test facility.
The REFLA/TRAC almost predicted the thermal-hydraulics in primary loops while the hydraulic models should be improved for regions at the pump side of loop seal and at the up-flow side of steam generator tube under CCFL condition. ‘The core thermal-hydraulic models in REFLA/TRAC give better prediction for core full-height differential pressure and the peak clad temperature (PCT) than those in original TRAC code. The PCT by the models in TRAC was lower about 100 K than the measured one but the PCT by those in REFLA/TRAC was lower only about 40K.’