[Federal Register Volume 76, Number 214 (Friday, November 4, 2011)]
[Notices]
[Pages 68511-68512]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-28608]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-498 and 50-499; NRC-2011-0238]


STP Nuclear Operating Company; South Texas Project, Units 1 and 
2; Exemption

1.0 Background

    STP Nuclear Operating Company (STPNOC, the licensee) is the holder 
of Facility Operating License Nos. NPF-76 and NPF-80, which authorizes 
operation of the South Texas Project (STP), Units 1 and 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, the Commission) now or hereafter in effect.
    The facility consists of a pressurized-water reactor located in 
Matagorda County in Texas.

2.0 Request/Action

    Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), 
Part 12, ``Specific exemptions,'' the licensee has, by letter dated 
December 21, 2010 (Agencywide Documents Access and Management System 
(ADAMS) Accession No. ML103630408), requested an exemption from 10 CFR 
50.46, ``Acceptance criteria for emergency core cooling systems 
[(ECCS)] for light-water nuclear power reactors,'' and Appendix K to 10 
CFR part 50, ``ECCS Evaluation Models.'' The regulations in 10 CFR 
50.46 contain acceptance criteria for the 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 assumes the use of 
zircaloy or ZIRLO \TM\, which is a material different from Optimized 
ZIRLO \TM\. The licensee's requested exemption 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 use of a different fuel rod 
cladding material. Accordingly, the licensee requested an exemption 
that would allow the use of Optimized ZIRLO \TM\ fuel rod cladding at 
STP, Units 1 and 2.

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 (1) When 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.

[[Page 68512]]

Authorized by Law

    This exemption would allow the use of Optimized ZIRLO \TM\ fuel rod 
cladding material at STP, Units 1 and 2. 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 ZIRLOTM,'' 
dated July 2006, contain the justification to use Optimized 
ZIRLOTM fuel rod cladding material in addition to Zircaloy-4 
and ZIRLOTM (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 NRC staff's safety evaluation for each topical report. 
Ring compression tests performed by Westinghouse on Optimized 
ZIRLOTM were reviewed and approved by the NRC staff (ADAMS 
Accession No. ML062080569), and demonstrate an acceptable retention of 
post-quench ductility up to the 10 CFR 50.46 limits of 2200 degrees 
Fahrenheit and 17 percent equivalent clad reacted. Furthermore, the NRC 
staff has concluded that oxidation measurements provided by the 
licensee illustrate that oxide thickness (and associated hydrogen 
pickup) for Optimized ZIRLOTM at any given burnup would be 
less than that for both zircaloy and ZIRLOTM (ADAMS 
Accession No. ML073130555). Hence, the NRC staff concludes that 
Optimized ZIRLOTM would be expected to maintain improved 
post-quench ductility over ZIRLOTM. Finally, the licensee 
stated that Westinghouse will perform an evaluation to ensure that the 
Optimized ZIRLOTM fuel rods continue to satisfy 10 CFR 50.46 
acceptance criteria utilizing currently NRC-approved loss-of-coolant 
accident (LOCA) models and methods.
    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. Since the use of 
the Baker-Just equation presumes the use of zircaloy-clad fuel, strict 
application of the rule would not permit use of the equation for 
Optimized ZIRLOTM cladding for determining acceptable fuel 
performance. Westinghouse has demonstrated that the Baker-Just model is 
conservative in all post-LOCA scenarios with respect to the use of the 
Optimized ZIRLOTM advanced alloy as a fuel cladding 
material.
    The NRC-approved topical reports have demonstrated that predicted 
chemical, thermal, and mechanical characteristics of the Optimized 
ZIRLOTM alloy cladding are bounded by those approved for 
ZIRLOTM 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 ZIRLOTM, 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 
ZIRLOTM.

Consistent With Common Defense and Security

    The proposed exemption would allow the use of Optimized 
ZIRLOTM fuel rod cladding material at STP, Units 1 and 2. 
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 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 ZIRLOTM, 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 ZIRLOTM fuel rod 
cladding material, the special circumstances required by 10 CFR 
50.12(a)(2)(ii) for the granting of an exemption 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 the licensee an exemption from 
the requirements of 10 CFR 50.46 and Appendix K to 10 CFR part 50, to 
allow the use of Optimized ZIRLOTM fuel rod cladding 
material at STP, 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 and published an environmental 
assessment for this exemption on October 11, 2011 (76 FR 62861).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 27th day of October 2011.

    For the Nuclear Regulatory Commission.
Michele G. Evans,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2011-28608 Filed 11-3-11; 8:45 am]
BILLING CODE 7590-01-P