One-dimensional modeling of radial heat removal during depressurized heatup transients in modular pebble-bed and prismatic high temperature gas-cooled reactors

Technical Report · Sun Jul 01 00:00:00 EDT 1984

DOI:https://doi.org/10.2172/6622530· OSTI ID:6622530

Savage, M. G.

A one-dimensional computational model was developed to evaluate the heat removal capabilities of both prismatic-core and pebble-bed modular HTGRs during depressurized heatup transients. A correlation was incorporated to calculate the temperature- and neutron-fluence-dependent thermal conductivity of graphite. The modified Zehner-Schluender model was used to determine the effective thermal conductivity of a pebble bed, accounting for both conduction and radiation. Studies were performed for prismatic-core and pebble-bed modular HTGRs, and the results were compared to analyses performed by GA and GR, respectively. For the particular modular reactor design studied, the prismatic HTGR peak temperature was 2152.2/sup 0/C at 38 hours following the transient initiation, and the pebble-bed peak temperature was 1647.8/sup 0/C at 26 hours. These results compared favorably with those of GA and GE, with only slight differences caused by neglecting axial heat transfer in a one-dimensional radial model. This study found that the magnitude of the initial power density had a greater effect on the temperature excursion than did the initial temperature.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6622530
• Report Number(s): ORNL/TM-9215; ON: DE84016746
• Resource Relation: Other Information: Portions are illegible in microfiche products. Original copy available until stock is exhausted
• Country of Publication: United States
• Language: English

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DEPRESSURIZATION
AFTER-HEAT
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REACTOR CORES
AFTER-HEAT REMOVAL
COMPUTER CALCULATIONS
GRAPHITE
HEAT TRANSFER
LOSS OF COOLANT
MATHEMATICAL MODELS
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TEMPERATURE DISTRIBUTION
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ELEMENTAL MINERALS
ELEMENTS
ENERGY TRANSFER
GAS COOLED REACTORS
GRAPHITE MODERATED REACTORS
INFORMATION
MINERALS
NONMETALS
NUMERICAL DATA
PHYSICAL PROPERTIES
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTORS
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