[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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