NUREG-1537, Part 2 - NRC

Review Procedures
-- HEU TOLEU CONVERSION
The reviewer should confirm that the submitted information systematically
considers all potential reactivity accidents analyzed for the existing'HEU-fueled
reactor and identifies the initiating event, and describes the function of key features
and components that significantly affect the course of the accident and the
consequences., The reviewer also'should confirm that information compares the
operating conditions and the changes in design6for'the proposed LEU-'fueled
reactor and identifies any factors that could change the evolution or consequences
from outcomes for the existing BEU-fueled reactor.- The reviewer should watch
for consequences'that could possiblymelt fuel,'challenge the integrity of the
cladding, or degrade the system core cooling characteristics.
The descriptions of the consequences for potential reactivity accidents in the
proposed LEU-fueled reactor should be compared with the acceptance criteria.
The reviewer should compare the licensee-provided information with applicable
accident analyses and events (e.g., Woodruff 1984).
Evaluation Findings
This section of the SAR should contain 'sufficient information to support one of the
three conclusions below, which should will included in the safety staffs evaluation
report:
The licensee has demonstrated that the conversion from HEU to LEU fuel
does not introduce the potential of a new reactivity addition accident not
previously analyzed for the HEU-fueled reactor or significantly increase the
consequences beyond those for an existing HEU-fueled reactor accident
In this assessment, the licensee presented the basic neutronic, thermalhydraulic,
and physical similarity between the HEU and LEU cores, and an
analysis showing that the conclusions in the' latest version of the HEU SAR
regarding the consequences of the maximum credible reactivity addition
accident are still applicable to the proposed LEU-fueled reactor.
Therefore, risk to the health and safety of reactor staff or the public does
not increase above that previously found acceptable for the HEU core from
the maximum reactivity addition accident.
or
* The licensee has demonstrated that, although the conversion from HEU to
LEU fuel does introduce the potential for a new reactivity addition accident
or significantly changes the results of an existing lEU scenario, the results
from the new safety aialysis give reasonable assurance that the proposed
LEU-fueled reactor is designed to avoid unacceptable fuel damage from
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