NUREG-1537, Part 2 - NRC

APPENDx 18 1
4.2.4 Neutron Source and Holder
The neutron startup source or holder usually need not be modified or replaced in
connectionwith HEU to LEU conversion. If it is, the design and operational
characteristics of the LEU components should be comparable to the source in the
BEU core. If the source or holder is not changed, the analyses should show that
the existing component will perform in the LEU-fueled reactor core without
significant decrease in its ability to function and maintain its integrity.
4.2.5 In-Core Experimental Facilities
The in-core experimental facilities or their intended uses might need to be changed
to accommodate the LEU fuel characteristics. Analyses of proposed changes in
experimental facilities and reactor operating conditions should show that these
changes wil not increase the risks of thermal or mechanical damage to the facility,
its contents, or reactor fueeL The analyses also should show that any change in
core reactivity conditions from experimental facilities in the LEU-fueled reactor
will not exceed the bases for applicable technical specifications, or the envelope of
analyzed and reviewed reactivity events for the reactor.
4.2.6. Reactor Materials
The design and operating specifications for core-related materials should show
them to be no less resistant to damage or degradation by the environment (e.g.,
neutron fluence or spectrum) in the LEU core than in the HEU core. The SAR
should show that any materials in the core to be changed in connection with
conversion, including the fuel meat and cladding, have been designed so that agig
effects (such as corrosion, erosion, radiation, temperature, metallurgical factors, or
mutual compatibility) will not significantly decrease the expected life of safetyrelated
components in the LEU corm
Review Proceares (Sections 4.2.1-4.2.6)
For al reactor core components, the emphasis should be to compare the design
criteria and bases of the proposed LEU core with those of the existing HEU core.
All features related to operations should be reviewed and compared. The reviewer
should determine if the proposed LEU core in the converted reactor will continue
to meet the design bases and operational objectives established for the lIEU-fueled
core. The reviewer should confirm that the licensee submitted all information
requested in the format and content guide.
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