[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