Thermal Hydraulic Analysis of a Low Enrichment Uranium Core for the MIT Research Reactor
Name
NFC-099.pdf
Description
NFC-099.pdf
Size
2.89 MB
Format
Adobe PDF
Checksum (MD5)
530723dd67bb02deac92c5efa95d713d
Author(s)
Ko, Yu-Chih
Hu, Lin-Wen
Kazimi, Mujid S.
Date Issued
January 2008
Publisher
Massachusetts Institute of Technology. Center for Advanced Nuclear Energy Systems. Nuclear Fuel Cycle Program
Series/Report no.
MIT-NFC;TR-099
Abstract
The MIT research reactor (MITR) is converting from the existing high enrichment
uranium (HEU) core to a low enrichment uranium (LEU) core using a high-density
monolithic UMo fuel. The design of an optimum LEU core for the MIT reactor is
evolving. The objectives of this study are to benchmark the in-house computer code for
the MITR, and to perform thermal hydraulic analyses in support of the LEU design
studies. The in-house multi-channel thermal-hydraulics code, MULCH-II, was developed
specifically for the MITR. This code was validated against PLTEMP for steady-state
analysis, and against RELAP5 and temperature measurements for the loss of primary
flow transient. The benchmark analysis results showed that the MULCH-II code is in
good agreement with other computer codes and experimental data, and hence it is used as
the main tool for this study.
Various fuel configurations are evaluated as part of the LEU core design optimization
study. The criteria adopted for the LEU thermal hydraulics analysis in this study of the
limiting safety system settings (LSSS), are to prevent onset of nucleate boiling during
steady-state operation, and to avoid a clad temperature excursion during the loss of flow
transient.
In ranking the LEU core design options, the primary parameter is a low power peaking
factor in order to increase the LSSS power and to decrease the maximum clad
temperature during the transient. The LEU fuel designs with 15 to 18 plates per element,
fuel thickness of 20 mils, and a hot channel factor less than 1.76 are shown to comply
with the thermal-hydraulic criteria. The steady-state power can potentially be higher than
6 MW, which was requested in the power upgrade submission to the Nuclear Regulatory
Commission.
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