An analytical study of a small-break loss-of-coolant accident with upper head injection
Upper head injection (UHI) is an emergency core coolant (ECC) system design that injects subcooled water into the upper head of the reactor vessel in a pressurized water reactor. An analysis has been performed that investigates the effects of UHI on small-break transient behavior. The analysis consists of several RELAP5/MOD1 computer code calculations, which have been compared to experimental data from a series of small-break loss-of-coolant accident simulations, performed in the Semiscale Mod-2A system. Small-break transient phenomena were calculated not to be significantly affected by the introduction of subcooled liquid into the vessel upper head. Nonequilibrium effects were minimal and limited to the period of ECC injection. The analysis covered a range of small-break sizes, and the severity of the transients (in terms of minimum core coolant level) was calculated to be a maximum (with or without UHI) for a cold leg break size of about 5.0% of the cold flow area. For all break sizes, UHI was calculated to increase the margin against core uncovery. The calculated hydraulic phenomena and specific fluid conditions were generally in good agreement with data. The calculated relative magnitudes of important phenomena were preserved over the break size spectrum.
- Research Organization:
- EG and G Idaho, Inc., P.O. Box 1625, Idaho Falls, Idaho 83401
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 5371085
- Journal Information:
- Nucl. Technol.; (United States), Vol. 62:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
COMPUTER CODES
R CODES
ECCS
LOSS OF COOLANT
COMPUTER CALCULATIONS
PWR TYPE REACTORS
HYDRAULICS
REACTOR ACCIDENTS
TRANSIENTS
ACCIDENTS
ENGINEERED SAFETY SYSTEMS
FLUID MECHANICS
MECHANICS
REACTOR PROTECTION SYSTEMS
REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
220900* - Nuclear Reactor Technology- Reactor Safety
210200 - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled