[Federal Register Volume 73, Number 53 (Tuesday, March 18, 2008)]
[Notices]
[Pages 14502-14503]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-5381]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-382]


Entergy Operations, Inc.; Waterford Steam Electric Station, Unit 
3; Exemption

1.0 Background

    Entergy Operations, Inc. (the licensee), is the holder of Facility 
Operating License No. NPF-38, which authorizes operation of the 
Waterford Steam Electric Station, Unit 3 (Waterford 3). 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 one pressurized-water reactor located in 
St. Charles Parish, Louisiana.

2.0 Request/Action

    Title 10 of the Code of Federal Regulations (10 CFR), 
50.46(a)(1)(i), ``Acceptance criteria for emergency core cooling 
systems for light-water nuclear power reactors,'' states:

    ``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 conforms 
to the criteria set forth in paragraph (b) of this section.''

    Paragraph I.A.5 of Appendix K to 10 CFR Part 50 states:

    ``Metal--Water Reaction Rate. The rate of energy release, 
hydrogen generation, and cladding oxidation from the metal/water 
reaction shall 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).''

    The April 24, 2007 exemption request relates to the specific types 
of cladding material specified in the regulations. As written, the 
regulations presume the use of zircaloy or ZIRLOTM fuel rod 
cladding. Also, 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. Thus, exemptions from the 
specific requirements of 10 CFR 50.46 and Appendix K to 10 CFR Part 50 
are needed to allow a cladding alloy other than zircaloy or 
ZIRLOTM.
    Accordingly, this exemption would result in changes to the plant by 
allowing only the use of an alternative cladding alloy other than 
zircaloy or ZIRLOTM in lieu of meeting the specific cladding 
requirements of 10 CFR 50.46 and Appendix K to 10 CFR Part 50. 
Specifically, the exemption would allow the use of Optimized 
ZIRLOTM cladding. All other requirements of 10 CFR 50.46 and 
of Appendix K to 10 CFR Part 50 would remain applicable.

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, and are consistent with the common defense and security; and 
(2) when special circumstances are present. As discussed below, special 
circumstances are present because the continued operation of Waterford 
3 with zircaloy or ZIRLOTM fuel rod cladding, rather than 
with Optimized ZIRLOTM, is

[[Page 14503]]

not necessary to achieve the underlying purpose of the rule.

Authorized by Law

    This exemption would result in changes to the plant by allowing use 
of an alternative cladding (Optimized ZIRLOTM) alloy other 
than zircaloy or ZIRLOTM in lieu of meeting the requirements 
of 10 CFR 50.46 and Appendix K to 10 CFR Part 50. As stated above, 10 
CFR 50.12 allows the NRC to grant exemptions from the requirements of 
10 CFR 50.46 and Appendix K to 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. The underlying purpose of 
Paragraph I.A.5 of Appendix K to 10 CFR Part 50 is to calculate the 
rates of energy, hydrogen concentration, and cladding oxidation from 
the metal-water reaction using the Baker-Just equation. Based on the 
above and on the NRC staff's previously documented topical report 
safety review as discussed further below, in the context of the 
proposed exemption, no new accident precursors are created by allowing 
the use of an alternative cladding (Optimized ZIRLOTM) alloy 
other than zircaloy or ZIRLOTM. Thus, the probability of 
postulated accidents is not increased. For the same reasons, 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 an alternative 
cladding (Optimized ZIRLOTM) alloy other than zircaloy or 
ZIRLOTM. This change to the plant has no relation to 
security issues. Therefore, the common defense and security is not 
impacted by this exemption.

Special Circumstances

    Pursuant to 10 CFR 50.12(a)(2)(ii), special circumstances are 
present whenever application 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. The 
underlying purpose of 10 CFR 50.46 is to establish acceptance criteria 
for adequate ECCS performance. 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\TM\ has been demonstrated by Westinghouse. Ring 
compression tests performed by Westinghouse on Optimized ZIRLO\TM\ 
(NRC-reviewed, approved, and documented in Appendix B of WCAP-12610-P-A 
and CENPD-404-P-A, Addendum 1-A, ``Optimized ZIRLO\TM\,'' July 2006, 
Agencywide Documents Access and Management System (ADAMS) Accession No. 
ML062080576) demonstrate an acceptable retention of post-quench 
ductility up to 10 CFR 50.46 limits of 2200 degrees Fahrenheit and 17 
percent equivalent clad reacted (ECR). Furthermore, the NRC staff has 
concluded that oxidation measurements provided by the licensee (letter 
from Westinghouse to NRC, ``SER Compliance with WCAP-12610-P-A & CENPD-
404-P-A Addendum 1-A `Optimized ZIRLO\TM\','' LTR-NRC-07-58, November 
6, 2007, ADAMS Accession No. ML073130562) illustrate that oxide 
thickness (and associated hydrogen pickup) for Optimized 
ZIRLOTM at any given burnup would be less than both 
zircaloy-4 and ZIRLO\TM\. Hence, the NRC staff concludes that Optimized 
ZIRLO\TM\ would be expected to maintain better post-quench ductility 
than ZIRLO\TM\. 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, 
Westinghouse will perform an evaluation to ensure that the Optimized 
ZIRLO\TM\ fuel rods continue to satisfy 10 CFR 50.46 acceptance 
criteria. For the reasons above, granting the exemption request will 
ensure that the underlying purpose of the rule is achieved.
    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 ZIRLO\TM\ cladding for determining acceptable 
fuel performance. However, the NRC staff has found that metal-water 
reaction tests performed by Westinghouse on Optimized ZIRLO\TM\ (NRC-
reviewed, approved, and 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 
agrees that application of Appendix K, paragraph I.A.5 is not necessary 
to achieve the underlying purpose of the rule in these circumstances. 
Accordingly, the NRC staff has determined that the special 
circumstances required by 10 CFR 50.12 (a)(2)(ii) for granting an 
exemption from the aforementioned specific paragraphs of 10 CFR 50.46 
and Appendix K of 10 CFR Part 50 exist.

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. 
Therefore, the Commission hereby grants Entergy Operations, Inc., an 
exemption from the specific cladding requirements of 10 CFR 50.46, 
``Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors,'' and of Appendix K to 10 CFR Part 50, 
``ECCS Evaluation Models,'' to allow the use of Optimized ZIRLO\TM\ 
fuel rod cladding material in future core reload applications for 
Waterford 3.
    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 October 22, 2007 (72 FR 59560).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 11th day of March 2008.

    For the Nuclear Regulatory Commission.
Catherine Haney,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
 [FR Doc. E8-5381 Filed 3-17-08; 8:45 am]
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