High-temperature gas-cooled reactors (HTGR) are passively safe, efficient, and
economical solutions to the worldÂs energy crisis. HTGRs are capable of generating high
temperatures during normal operation, introducing design challenges related to material
selection and reactor safety. Understanding heat transfer and fluid flow phenomena
during normal and transient operation of HTGRs is essential to ensure the adequacy of
safety features, such as the reactor cavity cooling system (RCCS). Modeling abilities of
system analysis codes, used to develop an understanding of light water reactor
phenomenology, need to be proven for HTGRs. RELAP5-3D v2.3.6 is used to generate
two reactor plant models for a code-to-code and a code-to-experiment benchmark
problem.
The code-to-code benchmark problem models the Russian VGM reactor for
pressurized and depressurized pressure vessel conditions. Temperature profiles
corresponding to each condition are assigned to the pressure vessel heat structure.
Experiment objectives are to calculate total thermal energy transferred to the RCCS for
both cases. Qualitatively, RELAP5-3DÂs predictions agree closely with those of other
system codes such as MORECA and Thermix. RELAP5-3D predicts that 80% of thermal energy transferred to the RCCS is radiant. Quantitatively, RELAP5-3D computes
slightly higher radiant and convective heat transfer rates than other system analysis
codes. Differences in convective heat transfer rate arise from the type and usage of
convection models. Differences in radiant heat transfer stem from the calculation of
radiation shape factors, also known as view or configuration factors. A MATLAB script
employs a set of radiation shape factor correlations and applies them to the RELAP5-3D
model.
This same script is used to generate radiation shape factors for the code-toexperiment
benchmark problem, which uses the Japanese HTTR reactor to determine
temperature along the outside of the pressure vessel. Despite lacking information on
material properties, emissivities, and initial conditions, RELAP5-3D temperature trend
predictions closely match those of other system codes. Compared to experimental
measurements, however, RELAP5-3D cannot capture fluid behavior above the pressure
vessel. While qualitatively agreeing over the pressure vessel body, RELAP5-3D
predictions diverge from experimental measurements elsewhere. This difference reflects
the limitations of using a system analysis code where computational fluid dynamics codes
are better suited.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3996 |
| Date | 16 August 2006 |
| Creators | Moore, Eugene James Thomas |
| Contributors | Hassan, Yassin A. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 1876204 bytes, electronic, application/pdf, born digital |
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