[Federal Register Volume 77, Number 88 (Monday, May 7, 2012)]
[Notices]
[Pages 26793-26795]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-10928]



[[Page 26793]]

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

NUCLEAR REGULATORY COMMISSION

[Docket No. 50-389; NRC-2011-0194]


Florida Power and Light Company, St. Lucie Plant, Unit No. 2, 
Exemption

1.0 Background

    The Florida Power & Light Company (FPL, the licensee) is the holder 
of Renewed Facility Operating License No. NPF-16, which authorizes 
operation of St. Lucie Plant, Unit No. 2 (St. Lucie, Unit 2). The 
license provides, among other things, that the facility is subject to 
all rules, regulations, and orders of the U.S. Nuclear Regulatory 
Commission (NRC or the Commission) now or hereafter in effect. The 
facility consists of two pressurized-water reactors located in Jensen 
Beach, Florida. However, this exemption is applicable only to St. 
Lucie, Unit 2.
    By letter dated April 28, 2011 (Agencywide Documents Access and 
Management System (ADAMS) Accession No. ML11119A136), the licensee 
submitted a request for an exemption from Title 10 of the Code of 
Federal Regulations (10 CFR) Part 50, Appendix G, to implement a 
revision of the pressure-temperature (P-T) operating limits for St. 
Lucie, Unit 2. In requesting the revisions to the P-T operating limits, 
the licensee referenced a topical report with a methodology for the P-T 
curves that did not meet some of the requirements of 10 CFR part 50, 
Appendix G, thus requiring the exemption pursuant to 10 CFR 50.12.

2.0 Request/Action

    Part 50 of 10 CFR, Appendix G, ``Fracture Toughness Requirements,'' 
which is invoked by 10 CFR 50.60, requires that P-T limits be 
established for the reactor coolant pressure boundary during normal 
operating and hydrostatic or leak rate testing conditions. 
Specifically, 10 CFR part 50, Appendix G, Section IV.A.2, states that 
``[t]he appropriate requirements on both the pressure-temperature 
limits and the minimum permissible temperature must be met for all 
conditions,'' and ``[t]he pressure-temperature limits identified as 
`ASME [American Society for Mechanical Engineers] Appendix G limits' in 
[T]able 3 require that the limits must be at least as conservative as 
limits obtained by following the methods of analysis and the margins of 
safety of Appendix G of Section XI of the ASME Code [Boiler and 
Pressure Vessel Code].'' The regulations in 10 CFR part 50, Appendix G 
also specify the use of the applicable editions and addenda of the ASME 
Code, Section XI, which are incorporated by reference in 10 CFR 50.55a. 
In the 2009 Edition of 10 CFR, the 1977 Edition through the 2004 
Edition of the ASME Code, Section XI, are incorporated by reference in 
10 CFR 50.55a. Finally, 10 CFR 50.60(b) states that, ``[p]roposed 
alternatives to the described requirements in Append[ix] G of this part 
or portions thereof may be used when an exemption is granted by the 
Commission under [10 CFR] 50.12.''
    In its January 23, 2008, LAR to implement the current St. Lucie 2 
technical specification (TS) P-T limits, the licensee provided the 
technical basis document for developing these P-T limits, Westinghouse 
Commercial Atomic Power report WCAP-16817-NP, Revision 2, ``St. Lucie 
Unit 2 RCS [reactor coolant system] Pressure and Temperature Limits and 
Low Temperature Overpressure Protection Report for 55 Effective Full 
Power Years'' (ADAMS Accession No. ML080290135). WCAP-16817-NP, 
Revision 2, references Combustion Engineering (CE) Owners Group Topical 
Report CE NPSD-683-A, Revision 6, ``Development of a RCS Pressure and 
Temperature Limits Report (PTLR) for the Removal of P-T Limits and LTOP 
Requirements from the Technical Specifications'' (ADAMS Accession No. 
ML011350387), as the methodology for determining the P-T limits. While 
WCAP-16917-NP, Revision 2, did not develop a separate PTLR for removal 
of the P-T limits from the St. Lucie 2 TSs, this report did utilize the 
methodology of CE NPSD-683-A, Revision 6, as the basis for calculating 
the P-T limits currently established in the St. Lucie 2 TSs. Use of the 
CE topical report requires an exemption.
    By letter dated April 28, 2011, the licensee requested an exemption 
from 10 CFR part 50, Appendix G, consistent with the requirements of 10 
CFR 50.12 and 50.60, to apply the KIm calculational 
methodology of CE NPSD-683-A, Revision 6, in the development of the St. 
Lucie, Unit 2, P-T limits. If a licensee proposes to use the 
methodology in CE NPSD-683-A, Revision 6, for the calculation of 
KIm, an exemption is required since the methodology for the 
calculation of KIm values in CE NPSD-683-A, Revision 6, 
cannot be shown to be equally or more conservative than the methodology 
for the determination of KIm provided in editions and 
addenda of the ASME Code, Section XI, Appendix G, through the 2004 
Edition.
    The NRC staff evaluated the specific PTLR methodology in CE NPSD-
683, Revision 6. This evaluation was documented in the NRC safety 
evaluation (SE) of March 16, 2001 (ADAMS Accession No. ML010780017), 
which specified additional licensee actions that are necessary to 
support a licensee's adoption of CE NPSD-683, Revision 6. The final 
approved version of this report was reissued as CE NPSD-683-A, Revision 
6, which included the NRC SE and the required additional action items 
as an attachment to the report. One of the additional specified actions 
(21) stated, ``(applicable only if the CE NSSS [nuclear steam 
supply system] methods for calculating KIm and 
KIt factors, as stated in Section 5.4 of CE NPSD-683, 
Revision 6, are being used as the basis for generating the P-T limits 
for their facilities) [licensees will need to] apply for an exemption 
against requirements of Section IV.A.2. of Appendix G to Part 50 to 
apply the CE NSSS methods to their P-T curves.'' The action item 
further stated, ``Exemption requests to apply the CE NSSS to the 
generation of P-T limit curves should be submitted pursuant to the 
provision of 10 CFR 50.60(b) and will be evaluated on a case-by-case 
basis against the exemption request acceptance criteria of 10 CFR 
50.12.''
    An exemption to use the methodology of CE NPSD-683-A to calculate 
the KIt factors is no longer necessary because editions and 
addenda of the ASME Code, Section XI, that have been incorporated by 
reference into 10 CFR 50.55a subsequent to the issuance of the final SE 
of CE NPSD-683-A, allow methods for determining the KIt 
factors that are equivalent to the methods described in CE NPSD-683-A.
    During the NRC staff's review of CE NPSD-683, Revision 6, the NRC 
staff evaluated the KIm calculational methodology of that 
report versus the methodologies for the calculation of KIm 
given in the ASME Code, Section XI, Appendix G. In the NRC's March 16, 
2001, SE., the staff noted, ``[t]he CE NSSS methodology does not invoke 
the methods in the 1995 edition of Appendix G to the Code for 
calculating KIm factors, and instead applies FEM [finite 
element modeling] methods for estimating the KIm factors for 
the RPV [reactor pressure vessel] shell * * * the staff has determined 
that the KIm calculation methods apply FEM modeling that is 
similar to that used for the determination of the KIt 
factors [as codified in the ASME Code, Section XI, Appendix G]. The 
staff has also determined that there is only a slight non-conservative 
difference between the P-T limits generated from the 1989 edition of 
[the ASME Code, Section XI,] Appendix G to the Code and those generated 
from CE NSSS methodology as documented in [CE/ABB] Evaluation

[[Page 26794]]

No. 063-PENG-ER-096, Revision 00, [`Technical Methodology Paper 
Comparing ABB/CE PT Curve to ASME Section III, Appendix G,' dated 
January 22, 1998 (ADAMS Accession No. ML100500514, nonproprietary 
version)]. The staff considers this difference to be reasonable and 
should be consistent with the expected improvements in P-T generation 
methods that have been incorporated into the 1995 edition of Appendix G 
to the Code.'' This conclusion regarding the comparison between the CE 
NSSS methodology and the 1995 Edition of the ASME Code, Section XI, 
Appendix G, methodology also applies to the 2004 Edition of the ASME 
Code, Section XI, Appendix G, methodology because there were no 
significant changes in the method of calculating the KIm 
factors required by the ASME Code, Section XI, Appendix G, between the 
1995 edition (through 1996 addenda) and the 2004 editions of the ASME 
Code. In summary, the staff concluded in its March 16, 2001, SE that 
the calculation of KIm using the CE NPSD-683, Revision 6 
methodology would lead to the development of P-T limit curves that may 
be slightly nonconservative with respect to those that would be 
calculated using the ASME Code, Section XI, Appendix G, methods, and 
that such a difference was to be expected with the development of more 
refined calculational techniques. Furthermore, the staff concluded in 
its March 16, 2001, SE that P-T limit curves that would be developed 
using the methodology of CE NPSD-683, Revision 6, would be adequate for 
protecting the RPV from brittle fracture under all normal operating and 
hydrostatic/leak test conditions.

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, are consistent with the common defense and security; and (2) 
when special circumstances are present.

Authorized by Law

    This exemption allows the use of an alternative methodology for 
calculating flaw stress intensity factors in the RPV due to membrane 
stress from pressure loadings in lieu of meeting the requirements in 10 
CFR 50.60 and 10 CFR part 50, Appendix G. As stated above, 10 CFR 50.12 
allows the NRC to grant exemptions from the requirements of 10 CFR part 
50. In addition, the granting of the exemption will not result in 
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 50.60 and 10 CFR part 50, Appendix 
G, is to provide an acceptable margin of safety against brittle failure 
of the RCS during any condition of normal operation to which the 
pressure boundary may be subjected over its service lifetime. 
Appropriate P-T limits are necessary to achieve this underlying 
purpose. The licensee's alternative methodology for establishing the P-
T limits and the LTOP setpoints is described in CE NPSD-683-A, Revision 
6, which has been approved by the NRC staff. Based on the above, no new 
accident precursors are created by using the alternative methodology. 
Thus, the probability of postulated accidents will not increase. Also, 
based on the above, the consequences of postulated accidents will not 
increase. In addition, the licensee used an NRC-approved methodology 
for establishing P-T limits and minimum permissible temperatures for 
the RPV. Therefore, there is no undue risk to the public health and 
safety.

Consistent With Common Defense and Security

    The exemption results in changes to the plant by allowing an 
alternative methodology for calculating flaw stress intensity factors 
in the RPV. This change to the calculation of stress intensity factors 
in the RPV material has no negative implications for security issues. 
Therefore, this exemption is consistent with the common defense and 
security.

Special Circumstances

    Special circumstances, pursuant to 10 CFR 50.12(a)(2)(ii), are 
present in that continued operation of St. Lucie, Unit 2, with P-T 
limit curves developed in accordance with the ASME Code, Section XI, 
Appendix G, is not necessary to achieve the underlying purpose of 10 
CFR part 50, Appendix G. Application of the KIm 
calculational methodology of CE NPSD-683-A, Revision 6, in lieu of the 
calculational methodology specified in the ASME Code, Section XI, 
Appendix G, provides an acceptable alternative evaluation procedure 
that will continue to meet the underlying purpose of 10 CFR part 50, 
Appendix G. The underlying purpose of the regulations in 10 CFR part 
50, Appendix G, is to provide an acceptable margin of safety against 
brittle failure of the reactor coolant system during any condition of 
normal operation to which the pressure boundary may be subjected over 
its service lifetime.
    Based on the staff's March 16, 2001, SE regarding CE NPSD-683, 
Revision 6, and the licensee's rationale to support the exemption 
request, the staff determined that an exemption is required to approve 
the use of the KIm calculational methodology of CE NPSD-683-
A, Revision 6. By letter dated January 29, 2009, in response to the 
licensee's January 23, 2008, LAR, the NRC staff issued an SE that 
provided its review of the licensee's calculations in WCAP-16917-NP, 
Revision 2, which referenced CE NPSD-683-A, Revision 6. Informed by 
these previous evaluations, the staff concludes that the application of 
the KIm calculational methodology of CE NPSD-683-A, Revision 
6, for St. Lucie, Unit 2, provides sufficient margin in the development 
of RPV P-T limit curves such that the underlying purpose of the 
regulations (10 CFR part 50, Appendix G) continues to be met. 
Therefore, the NRC staff concludes that the exemption requested by the 
licensee is justified based on the special circumstances of 10 CFR 
50.12(a)(2)(ii), ``[a]pplication of the regulation in the particular 
circumstances would not serve the underlying purpose of the rule or is 
not necessary to achieve the underlying purpose of the rule.'' Based 
upon a consideration of the conservatism that is incorporated into the 
methodologies of 10 CFR part 50, Appendix G, and ASME Code, Section XI, 
Appendix G, the staff concludes that application of the KIm 
calculational methodology of CE NPSD-683-A, Revision 6, as described, 
would provide an adequate margin of safety against brittle failure of 
the RPV. Therefore, the staff concludes that the exemption is 
appropriate under the special circumstances of 10 CFR 50.12(a)(2)(ii), 
and that the application of the KIm calculational 
methodology of CE NPSD-683-A, Revision 6, is acceptable for use as the 
basis for generating the St. Lucie, Unit 2, P-T limits.

4.0 Conclusion

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12(a), 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 under 10 
CFR 50.12(a)(2)(ii). Therefore, the Commission hereby grants FPL an 
exemption from the requirements of 10 CFR part 50, Appendix G, to allow 
application of the KIm calculational

[[Page 26795]]

methodology of CE NPSD-683-A, Revision 6, as the basis for the St. 
Lucie, Unit 2, P-T limits.
    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 (76 FR 53497; August 26, 2011). This 
exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 30th day of April 2012.

    For the Nuclear Regulatory Commission.
Michele G. Evans,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2012-10928 Filed 5-4-12; 8:45 am]
BILLING CODE 7590-01-P