Study of CRBR outlet plenum thermal oscillations during steady state conditions

Technical Report · Thu Jul 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7264389· OSTI ID:7264389

Lorenz, J J; Howard, P A

An experimental investigation of CRBR outlet plenum thermal oscillations during steady state conditions was conducted. Tests were performed using water with a fully mock-up 1/10-scale model of the CRBR upper plenum complete with Upper Internal Structure (UIS). The radial blanket/fuel assembly temperature difference was adjusted such that Froude number (ratio of buoyant to inertial forces) similitude of model and prototype was obtained. Temperature-time plots were obtained at 47 critical locations within the plenum. Power spectral density (PSD) analysis at particular locations was implemented to examine the frequency range of the thermal oscillations. It was found that significant outlet plenum thermal oscillations (peak to peak oscillation approximately 30 percent of fuel/blanket ..delta..T) occur only within the UIS mixing chamber in the region above the blanket assemblies. Power spectral density analysis revealed that the oscillations were in the frequency range 0-3 Hz (0-1.2 Hz prototype). Oscillations of this magnitude and frequency range are potentially serious from a design point of view. Outside the UIS, most components (e.g., support columns and vessel liner) were nearly at the mixed mean plenum temperature and oscillations were relatively small (less than 10 percent of the fuel/blanket ..delta..T). Leakage flow at the clearance gap (between the lower part of the UIS and top of the core) was found to be 7.8 percent (of the total flow) and 12.5 percent (of the total flow) for the 0.254 cm gap (nominal) and 0.508 cm gap, respectively. Doubling the leakage gap had a negligible influence on plenum temperatures; when the gap was eliminated altogether, only temperatures in the immediate neighborhood of the gap were affected.

• Research Organization: Argonne National Lab., Ill. (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7264389
• Report Number(s): ANL-CT-76-36
• Country of Publication: United States
• Language: English

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