Break Flow Rate Research Articles

The effects of break location on PWR small break LOCA: Experimental study at the ROSA-IV LSTF

This paper discusses the effect of break location on the break flow rate and break flow quality transitions during a small-break loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR). Results from five experiments conducted at the ROSA-IV Large Scale Test Facility (LSTF) are compared for this purpose. These experiments simulated a 2-inch break at the lower plenum, upper head, pressurizer top, cold leg, and hot leg, respectively. The controlling phenomena for the break flow quality transitions in cold-leg and hot-leg break experiments are described.

Pressurized water reactor core instrument tube ruptures: experimental simulation at the ROSA-IV lstf

A small-break loss-of-coolant accident (SBLOCA) initiated by the rupture of pressurized water reactor (PWR) core instrument tubes was simulated using the ROSA-IV Large Scale Test Facility (LSTF). The experimental results were characterized by a single-phase liquid discharge continuing for a long period until the pressure vessel coolant inventory was significantly depleted. This experiment was analyzed using three advanced LOCA analysis codes, RELAP5/MOD2, TRACPF1/MOD1 and CATHARE-1, to assess the predictive abilities of these codes. Although all these codes simulated the experimental results qualitatively, discrepancies were found between the predictions and data regarding the break flowrate, spatial distribution of coolant in the primary system and core rod temperature responses.

Investigation of BWR LOCA at ROSA-III — Effect of break configuration on system transients

The ROSA-III test facility is a volumetrically scaled ( 1 424 ) BWR/6 system with an electrically heated core to study the thermal-hydraulic response during a postulated loss-of-coolant accident (LOCA). Six loss-of-coolant experiments with a break area of 15%, 50% or 200% at the main recirculation pump inlet line were conducted at the ROSA-III test facility with a high pressure core spray failure. A sharp-edged orifice or a long throat nozzle was used as a break plane. It was found in the experiments that the break flow differences between the orifice and the nozzle break configurations with the same flow area were observed only in the subcooled break flow region. Subcooled break flow rate through the orifice was much larger than that through the nozzle. The break configuration difference had little influence on the other system responses, especially on the peak cladding temperature. The applicability of the test results to a BWR/6 has been confirmed through analyses of the 15% break ROSA-III LOCA experiments and BWR/6 LOCAs by using RELAP4/MOD6/U4/J3 code. The experimental results of the ROSA-III LOCA experiments were calculated well by the code, and the same trends were calculated in the BWR analyses.