[Federal Register Volume 75, Number 49 (Monday, March 15, 2010)]
[Notices]
[Pages 12312-12314]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-5557]


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NUCLEAR REGULATORY COMMISSION

[Docket No 50-395; NRC-2010-0077]


South Carolina Electric and Gas Company; Virgil C. Summer Nuclear 
Station, Unit 1; Exemption

1.0 Background

    The South Carolina Electric and Gas Company (SCE&G, the licensee) 
is the holder of Facility Operating License No. NPF-12 which authorizes 
operation of the Virgil C. Summer Nuclear Station, Unit 1 (VCSNS). The 
license provides, 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 a pressurized-water reactor located in 
Fairfield County in South Carolina.

2.0 Request/Action

    Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, 
``Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors,'' requires, among other items, that:

    Each boiling or pressurized light-water nuclear power reactor 
fueled with uranium oxide pellets within cylindrical zircaloy or 
ZIRLO cladding must be provided with an emergency core cooling 
system (ECCS) that must be designed so that its calculated cooling 
performance following postulated loss-of-coolant accidents [LOCAs] 
conforms to the criteria set forth in paragraph (b) of this section.

Appendix K to 10 CFR part 50, ``ECCS Evaluation Models,'' requires, 
among other items, that the rate of energy release, hydrogen 
generation, and cladding oxidation from the metal/water reaction shall 
be calculated using the Baker-Just equation. The regulations of 10 CFR 
50.46 and 10 CFR part 50, Appendix K, make no provision for use of fuel 
rods clad in a material other than zircaloy or ZIRLOTM. 
Since the chemical composition of the Optimized ZIRLOTM 
alloy differs from the specifications for zircaloy or 
ZIRLOTM, a plant-specific exemption is required to allow the 
use of the Optimized ZIRLOTM alloy as a cladding material at 
VCSNS. Therefore,

[[Page 12313]]

by letter dated June 9, 2009, the licensee requested an exemption that 
would allow the use of Optimized ZIRLOTM fuel rod cladding 
at VCSNS.

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

Authorized by Law

    This exemption results in allowing the use of Optimized 
ZIRLOTM fuel rod cladding material at the VCSNS. 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 adequate ECCS performance. By letter dated June 10, 2005, 
the NRC staff issued a safety evaluation (Addendum 1 SE) approving 
Addendum 1 to Westinghouse Topical Report WCAP-12610-P-A and CENPD-404-
P-A, ``Optimized ZIRLOTM'' (Agencywide Documents Access and 
Management System (ADAMS) Accession No. ML051670408), wherein the NRC 
staff approved the use of Optimized ZIRLOTM as a fuel 
cladding material. The NRC staff approved the use of Optimized 
ZIRLOTM as a fuel cladding material based on: (1) 
Similarities with standard ZIRLOTM, (2) demonstrated 
material performance, and (3) a commitment to provide irradiated data 
and validate fuel performance models ahead of burnups achieved in batch 
application. The NRC staff's safety evaluation for Optimized 
ZIRLOTM includes 10 conditions and limitations for its use.
    As previously documented in that safety evaluation, and subject to 
compliance with the specific conditions of approval established 
therein, the NRC staff finds that the applicability of the ECCS 
acceptance criteria to Optimized ZIRLOTM has been 
demonstrated by Westinghouse. Ring compression tests performed by 
Westinghouse on Optimized ZIRLOTM (documented in Appendix B 
of Addendum1-A to WCAP-12610-P-A and CENPD-404-P-A, ``Optimized 
ZIRLOTM,'' July 2006, ADAMS Accession No. ML062080576) 
demonstrate an acceptable retention of post-quench ductility up to 10 
CFR 50.46 limits of 2200 degrees Fahrenheit ([deg]F) and 17 percent 
equivalent clad reacted (ECR). Furthermore, the NRC staff concludes 
that oxidation measurements provided by Westinghouse in a letter to the 
NRC, ``SER [Safety Evaluation Report] Compliance with WCAP-12610-P-A & 
CENPD-404-P-A Addendum 1-A `Optimized ZIRLOTM' 
(Proprietary),'' LTR-NRC-07-58, November 2007, ADAMS Accession No. 
ML073130562) illustrate that oxide thickness (and associated hydrogen 
pickup) for Optimized ZIRLOTM at any given burnup would be 
less than for both zircaloy-4 and ZIRLOTM. Hence, the NRC 
staff concludes that Optimized ZIRLOTM would be expected to 
maintain better post-quench ductility than ZIRLOTM. This 
finding is further supported by an ongoing loss-of-coolant accident 
(LOCA) research program at Argonne National Laboratory, which has 
identified a strong correlation between cladding hydrogen content (due 
to in-service corrosion) and post-quench ductility.
    In addition, utilizing currently-approved LOCA models and methods, 
the licensee states that Westinghouse will perform an evaluation to 
ensure that the Optimized ZIRLOTM fuel rods continue to 
satisfy 10 CFR 50.46 acceptance criteria. For the reasons stated above, 
the NRC staff finds that granting the exemption request for the VCSNS 
will be consistent with the underlying purpose of the regulation.
    Paragraph I.A.5 of Appendix K to 10 CFR part 50 states that the 
rates of energy release, hydrogen concentration, and cladding oxidation 
from the metal-water reaction shall be calculated using the Baker-Just 
equation. Since 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. However, the NRC staff has found that 
metal-water reaction tests performed by Westinghouse on Optimized 
ZIRLOTM (documented in Appendix B of WCAP-12610-P-A and 
CENPD-404-P-A, Addendum 1-A and subject to compliance with the specific 
conditions of approval established therein) demonstrate conservative 
reaction rates relative to the Baker-Just equation. Thus, the NRC staff 
finds that the use of Optimized ZIRLOTM will achieve the 
underlying purpose of paragraph I.A.5 of Appendix K in this 
circumstance.
    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. In addition, the licensee 
will use NRC-approved methods for the reload design process for VCSNS 
reloads with Optimized ZIRLOTM. Therefore, there is no undue 
risk to public health and safety due to using Optimized 
ZIRLOTM.

Consistent With Common Defense and Security

    This exemption results in allowing the use of Optimized 
ZIRLOTM fuel rod cladding material at the VCSNS. This change 
to the plant core 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. 
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 granting of an exemption from 10 CFR 50.46 and 
Appendix K exist.

4.0 Conclusion

    The NRC staff has reviewed the licensee's request to use Optimized 
ZIRLOTM for fuel rod cladding material. Based on the NRC 
staff's evaluation as set forth above, the NRC staff concludes 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. Therefore, the Commission hereby grants 
SCE&G 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 up 
to a burnup of 62 GWd/MTU for the VCSNS.
    Pursuant to 10 CFR 51.32, the Commission has determined that the

[[Page 12314]]

granting of this exemption will not have a significant impact on the 
quality of the human environment as published in the Federal Register 
on March 3, 2010 (75 FR 9619). This exemption is effective upon 
issuance.

    Dated at Rockville, Maryland, this 8th day of March 2010.

    For the Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2010-5557 Filed 3-12-10; 8:45 am]
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