Outlet plenum mixing for transient overpower conditions of a one-exit nozzle LMFBR

Technical Report · Sat Apr 01 04:00:00 EST 1978

DOI:https://doi.org/10.2172/5010523· OSTI ID:5010523

Howard, P A

Two types of transient tests were employed to model a one-exit nozzle LMFBR outlet plenum. Water was used as a test fluid in the simulation of constant flowrates, Transient Overpower (TOP) conditions. In the first test, simulated fuel flow was 85% and blanket flow was 15%, whereas in the second test, the fuel flow was 100%. This allowed the assessment of the mitigating effects of blanket flow upon the exit nozzle temperature transient. The flow field was clearly three-dimensional, and a less active, though not stagnant, region was observed diametrically opposite the exit nozzle. During steady state, oscillations above the fuel-blanket interface were found to be small. This is attributed to the existence above the reactor core of a recirculating flow field, which served as an effective mixing agent. A simple lumped-parameter model, EXIT1, was developed to simulate TOP transient conditions for the test with both fuel and blanket flows. The predicted temperature profiles for various regions in the plenum were in good agreement with the experimental profiles, except for the region immediately above the reactor blanket. In devising the computer model, the temperature in this region was assumed to remain constant throughout the transient. However, this constant temperature did not prevail owing to the mixing that occurred in this region as a result of the recirculating flow field above the reactor core. The computer model can be readily modified to take into account the mixing due to this recirculation. In the test without blanket flow, good agreement between predictions and data was again obtained. In comparing results of the two tests, it was found that the blanket flow had only a small mitigating influence on the transient at the exit nozzle. The computer model can easily be extrapolated to reactor conditions.

• Research Organization: Argonne National Lab., Ill. (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5010523
• Report Number(s): ANL-CT-78-30
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210500 -- Power Reactors
Breeding
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
BREEDER REACTORS
EPITHERMAL REACTORS
EXCURSIONS
FAST REACTORS
FBR TYPE REACTORS
FLUID FLOW
FLUID MECHANICS
HYDRAULICS
LIQUID METAL COOLED REACTORS
LMFBR TYPE REACTORS
MECHANICS
MIXING
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR INTERNALS
REACTORS
TRANSIENTS