Nominal diameter 25mm is equal to 4.91 cm2. If we use this area the PCTRAN subcooled liquid discharge rate is too small to depressurize the primary coolant system to initiate the active boric accident pump (below 7.88 MPa) and HA-1 (5.9 MPa). So we started a break at the cold leg of size 12 cm2 instead. The sequence of events and transient results are very agreeable with the PSAR.
The SG emergency cooling system was started to conduct a 30 C/hr cooldown rate. PHRS was later started.