A scaling law for the local CHF on the external bottom side of a fully submerged reactor vessel
- Pennsylvania State Univ., University Park, PA (United States)
A scaling law for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water has been developed from the results of an advanced hydrodynamic CHF model for pool boiling on a downward facing curved heating surface. The scaling law accounts for the effects of the size of the vessel, the level of liquid subcooling, the intrinsic properties of the fluid, and the spatial variation of the local critical heat flux along the heating surface. It is found that for vessels with diameters considerably larger than the characteristic size of the vapor masses, the size effect on the local critical heat flux is limited almost entirely to the effect of subcooling associated with the local liquid head. When the subcooling effect is accounted for separately, the local CHF limit is nearly independent of the vessel size. Based upon the scaling law developed in this work, it is possible to merge, within the experimental uncertainties, all the available local CHF data obtained for various vessel sizes under both saturated and subcooled boiling conditions into a single curve. Applications of the scaling law to commercial-size vessels have been made for various system pressures and water levels above the heated vessel. Over the range of conditions explored in this study, the local CHF limit is found to increase by a factor of two or more from the bottom center to the upper edge of the vessel. Meanwhile, the critical heat flux at a given angular position of the heated vessel is also found to increase appreciably with the system pressure and the water level.
- Research Organization:
- US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Office of Nuclear Regulatory Research; Brookhaven National Lab. (BNL), Upton, NY (United States)
- OSTI ID:
- 467947
- Report Number(s):
- NUREG/CP-0157-VOL.2; CONF-9610202-Vol.2; ON: TI97004274; CNN: Contract NRC-04-93-061; TRN: 97:008413
- Resource Relation:
- Conference: 24. water reactor safety information meeting, Bethesda, MD (United States), 21-23 Oct 1996; Other Information: PBD: Feb 1997; Related Information: Is Part Of Proceedings of the twenty-fourth water reactor safety information meeting. Volume 2: Reactor pressure vessel embrittlement and thermal annealing; Reactor vessel lower head integrity; Evaluation and projection of steam generator tube condition and integrity; Monteleone, S. [comp.] [Brookhaven National Lab., Upton, NY (United States)]; PB: 443 p.
- Country of Publication:
- United States
- Language:
- English
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