Pressurizer surge line Counter Current Flow Limitation during AP600 Mode 5 Cold Shutdown

• Main Author: Colpo, Sarah E.
• Other Authors: Reyes, Jose N. Jr
• Language: en_US
• Published: 2012
• Subjects: Pressurized water reactors > Oregon > Testing; Pressurized water reactors > Emergency core cooling systems > Oregon
• Online Access: http://hdl.handle.net/1957/33578

Counter Current Flow Limitation (CCFL) was observed in the pressurizer surge line of the Oregon State University APEX facility during test NRC-10. This test simulated a one-inch diameter cold leg break with a failure of three of four of the fourth-stage Automatic Depressurization System (ADS) valves. The result was a high vapor flow rate through ADS 1-3, that caused CCFL in the pressurizer surge line and liquid holdup in the pressurizer. Because this liquid was not available for core cooling, further study of the passive safety systems in the AP600 under Mode 5 Cold Shutdown conditions was deemed necessary. An analysis of the AP600 geometry and the existing CCFL database determined that Kutateladze scaling is appropriate for the APEX and AP600 surge lines. The Kutateladze CCFL correlation was used to assess CCFL in the APEX and AP600 pressurizer surge lines under Mode 5 Cold Shutdown conditions. The results indicate that CCFL would be expected in the pressurizer surge lines at low pressures and decay powers prior to ADS 4 actuation. Test NRC-35 examined CCFL and provided data to benchmark NRC's thermal hydraulic analysis codes. This thesis presents the results of test NRC-35 and the supporting CCFL calculations. === Graduation date: 1999