Thermal-hydraulic simulation of natural convection decay heat removal in the High Flux Isotope Reactor (HFIR) using RELAP5 and TEMPEST: Part 2, Interpretation and validation of results
The RELAP5/MOD2 code was used to predict the thermal-hydraulic behavior of the HFIR core during decay heat removal through boiling natural circulation. The low system pressure and low mass flux values associated with boiling natural circulation are far from conditions for which RELAP5 is well exercised. Therefore, some simple hand calculations are used herein to establish the physics of the results. The interpretation and validation effort is divided between the time average flow conditions and the time varying flow conditions. The time average flow conditions are evaluated using a lumped parameter model and heat balance. The Martinelli-Nelson correlations are used to model the two-phase pressure drop and void fraction vs flow quality relationship within the core region. Systems of parallel channels are susceptible to both density wave oscillations and pressure drop oscillations. Periodic variations in the mass flux and exit flow quality of individual core channels are predicted by RELAP5. These oscillations are consistent with those observed experimentally and are of the density wave type. The impact of the time varying flow properties on local wall superheat is bounded herein. The conditions necessary for Ledinegg flow excursions are identified. These conditions do not fall within the envelope of decay heat levels relevant to HFIR in boiling natural circulation. 14 refs., 5 figs., 1 tab.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6422715
- Report Number(s):
- CONF-890173-1; ON: DE89006415
- Resource Relation:
- Conference: RELAPS users seminar, College Station, TX, USA, 31 Jan 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
HFIR REACTOR
HYDRAULICS
AFTER-HEAT REMOVAL
COMPUTERIZED SIMULATION
EQUATIONS
FLUID FLOW
HEAT TRANSFER
MASS TRANSFER
PRESSURE DROP
R CODES
COMPUTER CODES
ENERGY TRANSFER
ENRICHED URANIUM REACTORS
FLUID MECHANICS
IRRADIATION REACTORS
ISOTOPE PRODUCTION REACTORS
MECHANICS
REACTORS
REMOVAL
RESEARCH AND TEST REACTORS
RESEARCH REACTORS
SIMULATION
TANK TYPE REACTORS
TEST REACTORS
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
220600* - Nuclear Reactor Technology- Research
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990220 - Computers
Computerized Models
& Computer Programs- (1987-1989)