Environmental Impact Statement - radioactive monticello

Environmental Impacts of Postulated Accidents
* SAMA 28-develop a procedure to refill the condensate storage tank with fire service water
system.
0 SAMA 37-develop guidance to allow local, manual control for reactor core isolation cooling
system operation.
Since the ER was submitted, NMC has implemeted the six recommended SAMAs (SAMAs 2,
11, 12, 28, 36, and 37), and has reassessed the value of the remaining SAMAs.
Implementation of the six recommended SAMAs reduces the benefit of the remaining SAMAs
(including SAMA 9, which was identified as a result of the uncertainty analysis), such that only
one SAMA that has no been implemented yet, remains potentially cost-beneficial. SAMA 16
(passive overpressure relief for containment) becomes even more cost-beneficial because the
set of SAMAs implemented by NMC shifts the risk to categories influenced by containment
venting, which could be mitigated by SAMA 16. NMC stated that the improvement is being
pursued to determine if cost-effective modifications can be implemented (NMC 2005b).
The staff concludes that, with the exception of the one potentially cost-beneficial SAMA
discussed above, the costs of the SAMAs evaluated would be higher than the associated
benefits.
5.2.6 Conclusions
The staff reviewed NMC's analysis and concluded that the methods used and the
implementation of those methods were sound. The treatment of SAMA benefits and costs
support the general conclusion that the SAMA evaluations performed by NMC are reasonable
and sufficient for the license renewal submittal. Although the treatment of SAMAs for external
events was somewhat limited by the unavailability of an external event PSA, the likelihood of
there being cost-beneficial enhancements in this area was minimized by including several
candidate SAMAs related to dominant fire events, and increasing the estimated SAMA benefits
for internal events by a factor of two to account for potential benefits in external events.
Based on its review of the SAMA analysis, and on the implementation of the six recommended
low-cost SAMAs by NMC, the staff concurs with NMC's identification of areas in which risk can
be further reduced in a cost-beneficial manner through the implementation of one potentially
cost-beneficial SAMA. Given the potential for cost-beneficial risk reduction, the staff agrees
that further evaluation of this SAMA by NMC is warranted. However, this potentially
cost-beneficial SAMA does not relate to adequately managing the effects of aging during the
period of extended operation. Therefore, it need not be implemented as part of the license
renewal pursuant to 10 CFR Part 54.
NUREG-1437, Supplement 26 5-10 August 2006 1