NUREG-1537, Part 2 - NRC

APPENDIX 18.1
Review Procedires )
The reviewer should detennine if the scenarios and consequences of the MHA for
the HEU-fueled reactor and the proposed LEU-fueled reactor are significantly
different. If not different, the reviewer should follow the analysis by the licensee,
with quantitative checks at key steps as the accident scenario evolves. The
reviewer should compare the projected consequences of the MHA for the
proposed LEU-fueled reactor with the consequences of all other postulated
accidents to verify that those of the MHA exceed and envelope all others.
If the scenarios differ significantly, the reviewer should verify that the evolution of
the accident scenario is analyzed by applicable methods and should compare the
projected consequences with acceptance criteria. The reviewer should verify that
the projected consequences continue to comply with the acceptance criteria for
MHAs at the specific non-power reactor facility.
Evaluation Findngs
This section of the SAAR should contain sufficient information to support the
following types of conclusions, which will be included in the staff's safety
evaluation report. The reviewer should choose a conclusion from IA, IB, or IC
and conclusion 2:
(lA) The licensee has discussed the changes in fuel parameters, operating
characteristics, and procedures that result from conversion of the reactor
from HEU to LEU fuel. The effects of these changes on the assumptions
and analyses of the MHA postulated for the existing HEU-fueled reactor
are small enough so that the same MHA scenario is applicable for the
proposed LEU-fueled reactor.
(IB) The information and analyses for the MHAs of the two reactors were
compared. The steps and mechanisms for transport of fission products
from fuel to the unrestricted area are not significantly different, and any
change in the fission product inventory or other radioactive material
between the two reactors has been included in the analyses.
(IC) Changes to the reactor fuel, core, operating conditions anid procedures
required by the fuel conversion were shown to be significant The effects
on the previously postulated MHA for the HEU-fueled reactor were shown
to be large enough that a different MHA scenario was required for the
proposed LEU-fiueled reactor. The licensee adopted a different analytical
procedure that was demonstrated to be applicable by verification with the
HEU MHA (or with other acceptable analytical techniques and references).
The MHA for the LEU-fueled reactor was analyzed and appropriate, and o
NUREG-1537, PART 2 44 REV 0.2/96