Experiment data report for LOFT nuclear small break experiment L3-5/L3-5A

Uninterpreted data from the fourth nuclear small break loss-of-coolant experiment (Experiment L3-5/L3-5A) conducted in the Loss-of-Fluid Test (LOFT) facility are presented. The LOFT facility is a 50-MW(t) pressurized water reactor (PWR) system with instruments that measure and provide data on the thermal-hydraulic conditions during a postulated loss-of-coolant accident. The operation of the LOFT system is typical of large (approx.1000 MW(e)), commercial PWR operations. Experiment L3-5/L3-5A was conducted in two phases. The L3-5 phase in conjunction with Experiment L3-6, which will be conducted within the next few months, investigates the effect of pump operation on system response during a small break in the cold leg of the primary coolant system. The break size is equivalent to a 4-in. diameter rupture in a commercial plant, scaled on a break-area to system-volume basis. The principal variables investigated are system mass inventory and mass distribution. The L3-5 phase was a pumps-off experiment. The primary coolant pumps were tripped within a second of blowdown initiation which occurred immediately following reactor scram. The L3-5A phase evaluated the effectiveness of plant recovery by break isolation and steam generator ''feed and bleed'' cooldown. The potential for condensation cooling in the steam generator was also investigated.