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A 7.5-inch (285 cm2) cold leg LOCA with single failure (i.e. 2 out of 4 trains ECCS) available and loss of offsite power was benchmarked. The sequence of events and result form the design document are:
Please note in PCTRAN instead of plotting liquid and vapor break flows separately, the total is plotted. From 110 sec to 450 sec the specific enthalpy of the discharge flow is about 1200 Btu/lbm for pure vapor. There it coincides with MHI’s plot for vapor discharge. PCTRAN shows following the accumulator full discharge the break flow returns to liquid.
The extent of the RC pressure and inventory decrease, timing of core uncovery and clad heat-up, initiation of HPSI and accumulators, and reflood and refill of the vessel are all consistent between the two studies.