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Analysis of a PWR downcomer and lower plenum under asymmetric loop flow conditions

Conference ·
OSTI ID:5869160
Certain postulated transient conditions in a PWR may cause the flow rate and the temperature of the coolant entering the core from one of the cold leg loops to differ significantly from those in the other loops. When the flow rate and/or temperature of the loops are not balanced, the resulting thermal mixing at the core inlet will become nonuniform, and the assumption of perfect mixing is not only unwarranted, but may lead to an erroneous prediction of radial power distribution. The objective of this paper is to describe the results of the three-dimensional steady-state calculations for the analysis of thermal mixing in a PWR. The specific case chosen for the present study is one of the tests conducted in the Oconee-1 PWR. Those tests were conducted to determine the extent of downcomer and lower plenum mixing in response to various temperature differences or flow imbalances between the two coolant loops. These tests were performed specifically to obtain coolant temperature profiles at the core inlet, core outlet, and various axial locations in the core under imposed offset loop conditions. The calculations were performed using the COMMIX-1A computer code.
Research Organization:
Argonne National Lab., IL (USA); Electric Power Research Inst., Palo Alto, CA (USA); Commonwealth Edison Co., Chicago, IL (USA)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
5869160
Report Number(s):
CONF-850610-27; ON: DE85010296
Country of Publication:
United States
Language:
English