[Federal Register Volume 76, Number 61 (Wednesday, March 30, 2011)]
[Notices]
[Pages 17715-17717]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-7455]


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

NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-338 and 50-339; NRC-2010-0283]


Virginia Electric and Power Company North Anna Power Station, 
Units 1 and 2; Exemption

1.0 Background

    Virginia Electric and Power Company (VEPCO, the licensee) is the 
holder of Facility Operating License Nos. NPF-4 and NPF-7 which 
authorizes operation of the North Anna Power Station, Units 1 and 2 
(NAPS). 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 
Louisa County, Virginia.

2.0 Request/Action

    Title 10 of the Code of Federal Regulations (10 CFR), Part 50, 
Section 50.46, ``Acceptance criteria for emergency core cooling systems 
[ECCS] for light-water nuclear power reactors,'' requires that each 
power reactor meet the acceptance criteria for ECCS provided therein 
for zircaloy or ZIRLO <SUP>TM</SUP> cladding. Appendix K of 10 CFR Part 
50, ``ECCS Evaluation Models,'' requires the rate of energy release, 
hydrogen generation, and cladding oxidation from the metal/water 
reaction to be calculated using the Baker-Just equation (Baker, L., 
Just, L.C., ``Studies of Metal Water Reactions at High Temperatures, 
III. Experimental and Theoretical Studies of the Zirconium-Water 
Reaction,'' ANL-6548, page 7, May 1962).
    Both of the above requirements require the use of zircaloy or ZIRLO 
<SUP>TM</SUP> cladding. The licensee proposes to use Optimized ZIRLO 
<SUP>TM</SUP> as the cladding material and therefore is requesting an 
exemption from the requirements.
    In summary, by letter dated May 6, 2010, (Agencywide Documents 
Access and Management System (ADAMS), Accession No. ML101260517), the 
licensee requested an exemption from the requirements of 10 CFR 50.46 
and Appendix K to 10 CFR part 50. The reason for the exemption is to 
allow the use of Optimized ZIRLO <SUP>TM</SUP> as a cladding material.

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

[[Page 17716]]

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. These circumstances include the 
special circumstances that application of the regulation is not 
necessary to achieve the underlying purpose of the rule.

Authorized by Law

    This exemption would allow the licensee to use Optimized ZIRLO 
<SUP>TM</SUP> fuel rod cladding material at NAPS. 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 
(ADAMS Accession No. ML051670408), the NRC staff issued a safety 
evaluation (SE) approving Addendum 1 to Westinghouse Topical Report 
WCAP-12610-P-A and CENPD-404-P-A, ``Optimized ZIRLO <SUP>TM</SUP>'' 
(ADAMS Accession No. ML062080576) (portions of this topical report are 
non-publicly available because they contain proprietary information) 
(the report with the proprietary information removed is available at 
ADAMS Accession No. ML062080569), wherein the NRC staff approved the 
use of Optimized ZIRLO <SUP>TM</SUP> as a fuel cladding material. The 
NRC staff approved the use of Optimized ZIRLO <SUP>TM</SUP> as a fuel 
cladding material based on: (1) Similarities with ZIRLO <SUP>TM</SUP>, 
(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 SE for Optimized ZIRLO 
<SUP>TM</SUP> includes 10 conditions and limitations for its use. As 
previously documented in the NRC staff's review of topical reports 
submitted by Westinghouse Electric Company, LLC (Westinghouse), and 
subject to compliance with the specific conditions of approval 
established therein, the NRC staff finds that the applicability of 
these ECCS acceptance criteria to Optimized ZIRLO <SUP>TM</SUP> has 
been demonstrated by Westinghouse. Ring compression tests performed by 
Westinghouse on Optimized ZIRLO <SUP>TM</SUP> (NRC-reviewed, approved, 
and documented in Appendix B of WCAP-12610-P-A and CENPD-404-P-A, 
Addendum 1-A, ``Optimized ZIRLO <SUP>TM</SUP>'') (ADAMS Accession No. 
ML062080576) demonstrate an acceptable retention of post-quench 
ductility up to 10 CFR 50.46 limits of 2200[deg] 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 ZIRLO <SUP>TM</SUP> at any given burnup would be less than 
both zircaloy-4 and ZIRLO <SUP>TM</SUP>. Hence, the NRC staff concludes 
that Optimized ZIRLO <SUP>TM</SUP> would be expected to maintain better 
post-quench ductility than ZIRLO <SUP>TM</SUP>. 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.
    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 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 ZIRLO 
<SUP>TM</SUP> cladding for determining acceptable fuel performance. 
However, the NRC staff has found that metal-water reaction tests 
performed by Westinghouse on Optimized ZIRLO <SUP>TM</SUP> demonstrate 
conservative reaction rates relative to the Baker-Just equation and are 
bounding for those approved for ZIRLO <SUP>TM</SUP> under anticipated 
operational occurrences and postulated accidents.
    Based on the above, no new accident precursors are created by using 
Optimized ZIRLO <SUP>TM</SUP>, 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.

Consistent With Common Defense and Security

    The proposed exemption would allow the use of Optimized ZIRLO 
<SUP>TM</SUP> fuel rod cladding material at NAPS. 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 and to 
ensure that cladding oxidation and hydrogen generation are 
appropriately limited during a LOCA and conservatively accounted for in 
the ECCS evaluation model. The wording of the regulations in 10 CFR 
50.46 and Appendix K is not directly applicable to Optimized ZIRLO 
<SUP>TM</SUP>, 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 <SUP>TM</SUP> fuel rod cladding material, the special 
circumstances required by 10 CFR 50.12(a)(2)(ii) for the granting of an 
exemption from certain requirements of 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 VEPCO an exemption from certain 
requirements of 10 CFR 50.46 and Appendix K to 10 CFR Part 50, to allow 
the use of Optimized ZIRLO <SUP>TM</SUP> fuel rod cladding material, 
for NAPS.
    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 September 2, 2010 (75 FR 53984).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 23rd day of March 2011.

[[Page 17717]]

For the Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2011-7455 Filed 3-29-11; 8:45 am]
BILLING CODE 7590-01-P