[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]


-----------------------------------------------------------------------

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]
BILLING CODE 7590-01-P