Core boiling during midloop operation
- Yankee Atomic Electric Co., Bolton, MA (US)
The reactor coolant system (RCS) water level is reduced during each refueling at some plants. Decreasing the level below the top of the loop piping (midloop operation) may be necessary to work on unisolable RCS loop components. A loss of residual heat removal (RHR) under these conditions can be serious due to the reduced water inventory, air in the RCS, and openings in the RCS loops. Under certain conditions, a loss of RHR could lead to rapid core uncovery and potential fuel damage. Core boiling due to a loss of RHR during midloop operation has received little attention until recently. The transient involves complex phenomena induced by core boiling, such as inventory loss from RCS openings and differences between the downcomer and upper plenum water levels, with the reactor vessel acting like a manometer. These phenomena cannot be easily evaluated without a versatile thermal-hydraulic computer code such as RETRAN. This paper provides an analysis of these phenomena which reveals that the time to core uncovery is shortened by the loss of coolant through RCS openings and the manometer behavior of the reactor vessel water level. This analysis points out some limitations in applying the RETRAN code to this transient.
- OSTI ID:
- 5077645
- Journal Information:
- Nuclear Technology; (United States), Vol. 93:1; ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
REACTOR CORE DISRUPTION
REACTOR COOLING SYSTEMS
AUXILIARY WATER SYSTEMS
BOILING
COMPUTER CODES
HEAT TRANSFER
OPERATION
REACTOR FUELING
REACTOR VESSELS
TRANSIENTS
WATER
ACCIDENTS
AUXILIARY SYSTEMS
CONTAINERS
COOLING SYSTEMS
ENERGY SYSTEMS
ENERGY TRANSFER
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REACTOR ACCIDENTS
REACTOR COMPONENTS
220900* - Nuclear Reactor Technology- Reactor Safety
990200 - Mathematics & Computers