[Federal Register Volume 75, Number 234 (Tuesday, December 7, 2010)]
[Notices]
[Pages 76051-76052]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-30653]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-282 and 50-306; NRC-2010-0324]
Northern States Power Company--Minnesota, Prairie Island Nuclear
Generating Plant, Units 1 and 2; Exemption
1.0 Background
Northern States Power Company, a Minnesota corporation (NSPM, the
licensee) is the holder of Facility Operating License Nos. DPR-42 and
DPR-60, which authorize operation of the Prairie Island Nuclear
Generating Plant, Units 1 and 2 (PINGP). The licenses provide, among
other things, that the facility is subject to all rules, regulations,
and orders of the Nuclear Regulatory Commission (NRC, the Commission)
now or hereafter in effect.
The facility consists of two pressurized-water reactors located in
Goodhue County in Minnesota.
2.0 Request/Action
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR),
Sec. 50.12, ``Specific exemptions,'' NSPM has, by letter dated
November 24, 2009, as supplemented by letter dated May 26, 2010
(Agencywide Documents Access and Management System Accession Nos.
ML093280883 and ML101480083, respectively), requested an exemption from
10 CFR 50.46, ``Acceptance criteria for emergency core cooling systems
for light-water nuclear power reactors,'' and appendix K to 10 CFR part
50, ``ECCS Evaluation Models,'' (appendix K). The regulations in 10 CFR
50.46 contain acceptance criteria for the emergency core cooling system
(ECCS) for reactors fueled with zircaloy or ZIRLO\TM\ cladding. In
addition, appendix K to 10 CFR part 50 requires that the Baker-Just
equation be used to predict the rates of energy release, hydrogen
concentration, and cladding oxidation from the metal/water reaction.
The Baker-Just equation assumed the use of a zirconium alloy different
than Optimized ZIRLO\TM\. The exemption request relates solely to the
specific types of cladding material specified in these regulations. As
written, the regulations presume the use of zircaloy or ZIRLO\TM\ fuel
rod cladding. Thus, an exemption from the requirements of 10 CFR 50.46
and Appendix K is needed to support the
[[Page 76052]]
use of different fuel rod cladding material. Therefore, the licensee
requested an exemption that would allow the use of Optimized ZIRLO\TM\
fuel rod cladding at PINGP. The NRC staff will prepare a separate
safety evaluation, fully addressing NSPM's application for a related
license amendment.
3.0 Discussion
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR part 50 when (1) the exemptions are
authorized by law, will not present an undue risk to public health or
safety, and are consistent with the common defense and security; and
(2) when special circumstances are present. Under 10 CFR 50.12(a)(2),
special circumstances include, among other things, when application of
the specific regulation in the particular circumstance would not serve,
or is not necessary to achieve, the underlying purpose of the rule.
Authorized by Law
This exemption would allow the use of Optimized ZIRLO\TM\ fuel rod
cladding material at PINGP. As stated above, 10 CFR 50.12 allows the
NRC to grant exemptions from the requirements of 10 CFR part 50. The
NRC staff has determined that granting of the licensee's proposed
exemption will not result in a violation of the Atomic Energy Act of
1954, as amended, or the Commission's regulations. Therefore, the
exemption is authorized by law.
No Undue Risk to Public Health and Safety
The underlying purpose of 10 CFR 50.46 is to establish acceptance
criteria for ECCS performance. Westinghouse topical reports WCAP-12610-
P-A and CENPD-404-P-A, Addendum 1-A, ``Optimized ZIRLO\TM\,'' dated
July 2006, contain the justification to use Optimized ZIRLO\TM\ fuel
rod cladding material in addition to Zircaloy-4 and ZIRLO\TM\ (these
topical reports are non-publicly available because they contain
proprietary information). The NRC staff approved the use of these
topical reports, subject to the conditions stated in the staff's safety
evaluations for each. In these topical reports, Westinghouse evaluated
the structural and material properties of Optimized ZIRLO\TM\ and
determined that the use of Optimized ZIRLO\TM\ as cladding would have
either no significant impact or would produce a reduction in corrosion
or oxidation and a corresponding reduction in hydrogen pickup.
Westinghouse also evaluated the impact of Optimized ZIRLO\TM\ fuel
cladding on the loss-of-coolant accident (LOCA) and non-LOCA accident
analyses. The evaluations determined that the LOCA analyses for fuel
with Optimized ZIRLO\TM\ cladding complied with 10 CFR 50.46, and that
there was a negligible difference in the non-LOCA analyses between fuel
clad with standard ZIRLO\TM\ and fuel clad with Optimized ZIRLO\TM\.
The underlying purpose of 10 CFR Part 50, Appendix K, Section
I.A.5, ``Metal-Water Reaction Rate,'' is to ensure that cladding
oxidation and hydrogen generation are appropriately limited during a
LOCA and conservatively accounted for in the ECCS evaluation model.
Appendix K of 10 CFR part 50 requires that the Baker-Just equation be
used in the ECCS evaluation model to determine the rate of energy
release, cladding oxidation, and hydrogen generation. Westinghouse has
shown in WCAP-12610-P-A that the Baker-Just model is conservative in
all post-LOCA scenarios with respect to the use of the Optimized
ZIRLO\TM\ advanced alloy as a fuel cladding material.
The NRC-approved topical reports have demonstrated that predicted
chemical, thermal, and mechanical characteristics of the Optimized
ZIRLO\TM\ alloy cladding are bounding for those approved for ZIRLO\TM\
under anticipated operational occurrences and postulated accidents.
Reload cores are required to be operated in accordance with the
operating limits specified in the technical specifications and the core
operating limits report.
Based on the above, no new accident precursors are created by using
Optimized ZIRLO\TM\; thus, the probability of postulated accidents is
not increased. Also, based on the above, the consequences of postulated
accidents are not increased. Therefore, there is no undue risk to
public health and safety due to using Optimized ZIRLO\TM\.
Consistent With Common Defense and Security
The proposed exemption would allow the use of Optimized ZIRLO\TM\
fuel rod cladding material at PINGP. This change to the plant
configuration has no relation to security issues. Therefore, the common
defense and security is not impacted by this exemption.
Special Circumstances
Special circumstances, in accordance with 10 CFR 50.12(a)(2)(ii),
are present whenever application of the regulation in the particular
circumstances is not necessary to achieve the underlying purpose of the
rule. The underlying purpose of 10 CFR 50.46 and Appendix K to 10 CFR
part 50 is to establish acceptance criteria for ECCS performance. The
wording of the regulations in 10 CFR 50.46 and Appendix K is not
directly applicable to Optimized ZIRLO\TM\, even though the evaluations
above show that the intent of the regulation is met. Therefore, since
the underlying purposes of 10 CFR 50.46 and Appendix K are achieved
through the use of Optimized ZIRLO\TM\ fuel rod cladding material, the
special circumstances required by 10 CFR 50.12(a)(2)(ii) for the
granting of an exemption from 10 CFR 50.46 and Appendix K exist.
4.0 Conclusion
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12, the exemption is authorized by law, will not present an undue
risk to the public health and safety, and is consistent with the common
defense and security. Also, special circumstances are present.
Therefore, the Commission hereby grants NSPM an exemption from the
requirements of 10 CFR 50.46 and Appendix K to 10 CFR part 50, to allow
the use of Optimized ZIRLO\TM\ fuel rod cladding material, for the
Prairie Island Nuclear Generating Plant, Units 1 and 2.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will not have a significant effect on the
quality of the human environment as published in the Federal Register
on October 14, 2010 (75 FR 63213).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 22nd day of November, 2010.
For the Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. 2010-30653 Filed 12-6-10; 8:45 am]
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