[Federal Register Volume 81, Number 126 (Thursday, June 30, 2016)]
[Notices]
[Pages 42756-42759]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-15548]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-369 and 50-370; NRC-2016-0128]


Duke Energy Carolinas, LLC and North Carolina Electric Membership 
Corporation; Acceptance Criteria for Emergency Core Cooling Systems, 
McGuire Nuclear Station, Units 1 and 2, Catawba Nuclear Station, Units 
1 and 2

AGENCY: Nuclear Regulatory Commission.

ACTION: Exemption; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is issuing an 
exemption in response to a license amendment request and exemption 
request dated August 20, 2015, from Duke Energy Carolinas, LLC (Duke 
Energy or the licensee) from portions of the regulations to support the 
use of fuel that is clad in Optimized ZIRLO\TM\.

ADDRESSES: Please refer to Docket ID NRC-2016-0128 when contacting the 
NRC about the availability of information regarding this document. You 
may obtain publicly-available information related to this document 
using any of the following methods:
     Federal Rulemaking Web site: Go to http://www.regulations.gov and search for Docket ID NRC-2016-0128. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: [email protected].
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly-available documents online in the 
ADAMS Public Documents collection at http://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and 
then select ``Begin Web-based ADAMS Search.'' For problems with ADAMS, 
please contact the NRC's Public Document Room (PDR) reference staff at 
1-800-397-4209, 301-415-4737, or by email to [email protected]. The 
ADAMS accession number for each document referenced (if it is available 
in ADAMS) is provided the first time that it is mentioned in this 
document.
     NRC's PDR: You may examine and purchase copies of public 
documents at the NRC's PDR, Room O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: G. Edward Miller, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington DC 
20555-0001; telephone: 301-415-2481, email [email protected].

SUPPLEMENTARY INFORMATION: 

I. Background

    Duke Energy is the holder of Facility Operating License Nos. NPF-9, 
NPF-17, NPF-35, and NPF-52, which authorize operation of the McGuire 
Nuclear Station (MNS), Units 1 and 2, and Catawba Nuclear Station 
(CNS), Units 1 and 2. The licenses provide, among other things, that 
each facility is subject to all rules, regulations, and orders of the 
NRC now or hereafter in effect.
    The MNS and CNS units are pressurized-water reactor located in 
Mecklenburg County, North Carolina, and York County, South Carolina, 
respectively.

II. Request/Action

    Pursuant to section 50.12 of title 10 of the Code of Federal 
Regulations (10

[[Page 42757]]

CFR), ``Specific Exemptions,'' the licensee has, by letter dated August 
20, 2015 (ADAMS Accession No. ML15295A016), 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'' to allow the use of fuel rods 
clad with Optimized ZIRLO\TM\. Section 50.46 requires that the 
calculated cooling performance following postulated loss-of-coolant 
accidents at reactors fueled with zircaloy or ZIRLO[supreg] cladding 
conforms to the criteria set forth in paragraph (b) of that section. In 
addition, appendix K to 10 CFR part 50, in part, 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[supreg], materials that have different chemical compositions from 
Optimized ZIRLO\TM\. As written, these regulations presume only the use 
of zircaloy or ZIRLO[supreg] fuel rod cladding and do not contain 
provisions for use of fuel rods with other cladding materials. 
Therefore, an exemption from the requirements of 10 CFR 50.46 and part 
50, 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 
MNS and CNS.

III. 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 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. However, Sec.  
50.12(a)(2) states that the Commission will not consider granting an 
exemption unless special circumstances are present as set forth in 
Sec.  50.12(a)(2). Under 10 CFR 50.12(a)(2)(ii), special circumstances 
are present when application of the regulation in the particular 
circumstances would not serve, or is not necessary to achieve, the 
underlying purpose of the rule.

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 to 
provide reassurance of safety in the event of a loss-of-coolant (LOCA) 
accident. Although the wording of the regulations in 10 CFR 50.46 and 
appendix K is not expressly applicable to Optimized ZIRLOTM, 
the evaluations described in the following sections of this exemption 
show that the purpose of the regulations are met by this exemption in 
that, subject to certain conditions, the acceptance criteria are valid 
for Optimized ZIRLO\TM\ fuel cladding material, Optimized ZIRLO\TM\ 
would maintain better post-quench ductility, and the Baker-Just 
equation conservatively bounds LOCA scenario metal-water reaction rates 
and is applicable to Optimized ZIRLO\TM\. Because the underlying 
purposes of 10 CFR 50.46 and appendix K can be achieved through the 
application of these requirements to 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.

The Exemption Is Authorized by Law

    This exemption would allow the use of fuel rods clad with Optimized 
ZIRLO\TM\ in future core reload applications for MNS and CNS. Section 
50.12 allows the NRC to grant exemptions from the requirements of 10 
CFR part 50 provided that the exemptions are authorized by law. The NRC 
staff determined that special circumstances exist to grant the proposed 
exemption and that granting the exemption would not result in a 
violation of the Atomic Energy Act of 1954, as amended. Therefore, the 
exemption is authorized by law.

No Undue Risk to Public Health and Safety

    The provisions of 10 CFR 50.46 establish acceptance criteria for 
ECCS performance. Westinghouse topical reports WCAP-12610-P-A and 
CENPD-404-P-A, Addendum 1-A, ``Optimized ZIRLO\TM\,'' dated July 2006, 
contain the justification to use Optimized ZIRLOTM fuel rod 
cladding material in addition to Zircaloy-4 and ZIRLO[supreg]. The 
complete topical reports are not publicly available because they 
contain proprietary information, however, a redacted version and the 
NRC safety evaluation are available under ADAMS Accession No. 
ML062080569. The NRC staff found that the Westinghouse topical reports 
demonstrated the applicability of these ECCS acceptance criteria to 
Optimized ZIRLO\TM\, subject to the compliance with the specific 
conditions of approval established therein. The NRC staff reviewed the 
August 20, 2015, application against these specific conditions and 
found that the licensee was in compliance with all of the applicable 
conditions. The NRC staff's review of these specific conditions for MNS 
and CNS can be found under ADAMS Accession No. ML16105A326.
    Ring compression tests performed by Westinghouse on Optimized 
ZIRLOTM were reviewed and approved by the NRC staff in 
topical report WCAP-14342-A & CENPD-404-NP-A, Addendum 1-A, and 
demonstrate an acceptable retention of post-quench ductility up to the 
10 CFR 50.46 limits of 2,200 degrees Fahrenheit and 17 percent 
equivalent clad reacted. Furthermore, the NRC staff has concluded that 
oxidation measurements provided by Westinghouse illustrate that oxide 
thickness (and associated hydrogen pickup) for Optimized ZIRLO\TM\ at 
any given burnup would be less than that for both zircaloy and 
ZIRLOTM (ADAMS Package Accession No. ML073130555). Hence, 
the NRC staff concludes that Optimized ZIRLOTM would be 
expected to maintain acceptable post-quench ductility.
    The provisions of 10 CFR part 50, appendix K, paragraph I.A.5, 
``Metal-Water Reaction Rate,'' serve to ensure that cladding oxidation 
and hydrogen generation are limited appropriately during a loss-of-
coolant accident (LOCA) and conservatively accounted for in the ECCS 
evaluation model. That regulation 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. As concluded in the NRC staff safety evaluation for the 
associated topical report, Westinghouse demonstrated that the Baker-
Just model is conservative in all post-LOCA scenarios with respect to 
the use of the Optimized ZIRLOTM 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 
ZIRLO[supreg] 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.

[[Page 42758]]

    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 ZIRLO\TM\.

Consistent With Common Defense and Security

    The proposed exemption would allow the use of Optimized ZIRLO\TM\ 
fuel rod cladding material at MNS and CNS. This change to the plant 
configuration is adequately controlled by TS requirements and is not 
related to security issues. Because the common defense and security is 
not impacted by this exemption, the exemption is consistent with the 
common defense and security.

Environmental Considerations

    The NRC staff determined that the exemption discussed herein meets 
the eligibility criteria for the categorical exclusion set forth in 10 
CFR 51.22(c)(9) because it is related to a requirement concerning the 
installation or use of a facility component located within the 
restricted area, as defined in 10 CFR part 20, and issuance of this 
exemption involves: (i) No significant hazards consideration, (ii) no 
significant change in the types or a significant increase in the 
amounts of any effluents that may be released offsite, and (iii) no 
significant increase in individual or cumulative occupational radiation 
exposure. Therefore, in accordance with 10 CFR 51.22(b), no 
environmental impact statement or environmental assessment need be 
prepared in connection with the NRC's consideration of this exemption 
request. The basis for the NRC staff's determination is discussed as 
follows with an evaluation against each of the requirements in 10 CFR 
51.22(c)(9)(i)-(iii).

Requirements in 10 CFR 51.22(c)(9)(i)

    The NRC staff evaluated whether the exemption involves no 
significant hazards consideration using the standards described in 10 
CFR 50.92(c), as presented below:
    1. Does the proposed exemption involve a significant increase in 
the probability or consequences of an accident previously evaluated?
    Response: No.
    The proposed TS changes add flexibility in the selection of fuel 
rod cladding materials for use at CNS and MNS. The proposed change of 
adding a cladding material does not result in an increase to the 
probability or consequences of an accident previously evaluated. TS 
4.2.1 addresses the fuel assembly design, and currently specifies that, 
``Each assembly shall consist of a matrix of either ZIRLO[supreg] or 
Zircaloy fuel rods . . .'' The proposed change will add Optimized 
ZIRLO\TM\ to the approved fuel rod cladding materials listed in this 
TS. In addition, a reference to the Westinghouse VANTAGE+ fuel assembly 
core reference report, WCAP-12610-P-A, and the topical report for 
Optimized ZIRLO\TM\, WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, 
will be included in the listing of approved methods used to determine 
the core operating limits for CNS and MNS given in TS 5.6.5.b. 
Westinghouse topical report WCAP-12610-P-A and CENPD-404-P-A, Addendum 
1-A, Optimized ZIRLO\TM\, provides the details and results of material 
testing of Optimized ZIRLO\TM\ compared to standard ZIRLO[supreg], as 
well as the material properties to be used in various models and 
methodologies when analyzing Optimized ZIRLO\TM\. As the nuclear 
industry pursues longer operating cycles with increased fuel discharge 
burnup and fuel duty, the corrosion performance requirements for the 
nuclear fuel cladding become more demanding. Optimized ZIRLO\TM\ was 
developed to meet these industry needs by providing a reduced corrosion 
rate while maintaining the composition and physical properties, such as 
mechanical strength, similar to standard ZIRLO[supreg]. Fuel rod 
internal pressure has also become more limiting due to changes such as 
increased fuel duty and use of integral fuel burnable absorbers. 
Reducing the associated corrosion buildup by using Optimized ZIRLO\TM\ 
in turn reduces temperature feedback effects, providing additional 
margin to the fuel rod internal pressure design criterion. Fuel with 
Optimized ZIRLO\TM\ cladding will continue to satisfy the pertinent 
design basis operating limits, so cladding integrity is maintained. 
There are no changes that will adversely affect the ability of existing 
components and systems to mitigate the consequences of any accident. 
Therefore, addition of Optimized ZIRLO\TM\ to the allowable cladding 
materials for CNS and MNS does not result in an increase in the 
probability or consequences of an accident previously evaluated.
    The NRC has previously approved use of Optimized ZIRLO\TM\ fuel 
cladding material in Westinghouse fueled reactors provided that 
licensees ensure compliance with the Conditions and Limitations set 
forth in the NRC Safety Evaluation for the topical report. Confirmation 
that these Conditions are satisfied is performed as part of the normal 
core reload process.
    Therefore, the proposed change does not involve a significant 
increase in the probability or consequences of an accident previously 
evaluated.
    2. Does the proposed exemption create the possibility of a new or 
different kind of accident from any accident previously evaluated?
    Response: No.
    The proposed TS changes add flexibility in the selection of fuel 
rod cladding materials for use at CNS and MNS. Optimized ZIRLO\TM\ was 
developed to provide a reduced cladding corrosion rate while 
maintaining the benefits of mechanical strength and resistance to 
accelerated corrosion from potential abnormal chemistry conditions. The 
fuel rod design bases are established to satisfy the general and 
specific safety criteria addressed in the CNS and MNS UFSAR [Updated 
Final Safety Analysis Report], Chapter 15 (Accident Analyses). The fuel 
rods are designed to prevent excessive fuel temperatures, excessive 
fuel rod internal gas pressures due to fission gas releases, and 
excessive cladding stresses and strains. Westinghouse topical report 
WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A, Optimized ZIRLO\TM\, 
provides the details and results of material testing of Optimized 
ZIRLO\TM\ compared to standard ZIRLO[supreg], as well as the material 
properties to be used in various models and methodologies when 
analyzing Optimized ZIRLO\TM\. The original fuel design basis 
requirements have been maintained. No new single failure mechanisms 
will be created, and there are no alterations to plant equipment or 
procedures that would introduce any new or unique operational modes or 
accident precursors. Therefore, addition of another approved cladding 
material of similar composition and properties as the current approved 
cladding materials to the CNS and MNS TS does not create the 
possibility of a new or different kind of accident or malfunction from 
those previously evaluated within the UFSAR.
    3. Does the proposed exemption involve a significant reduction in a 
margin of safety?
    Response: No.
    The proposed change will not involve a significant reduction in the 
margin of safety because it has been demonstrated that the material 
properties of the Optimized ZIRLO\TM\ are not significantly different 
from those of standard ZIRLO[supreg]. Optimized ZIRLO\TM\ is expected 
to perform similarly to

[[Page 42759]]

standard ZIRLO[supreg] for all normal operating and accident scenarios, 
including both loss of coolant accident (LOCA) and non-LOCA scenarios. 
For LOCA scenarios, where the slight difference in Optimized ZIRLO\TM\ 
material properties relative to standard ZIRLO[supreg] could have some 
impact on the overall accident scenario, plant-specific LOCA analyses 
using Optimized ZIRLO\TM\ properties demonstrates that the acceptance 
criteria of 10 CFR 50.46 has been satisfied, therefore, the proposed 
change does not involve a significant reduction in a margin of safety.
    Based on the above, the NRC staff concludes that the proposed 
exemption involves no significant hazards consideration. Accordingly, 
the requirements of 10 CFR 51.22(c)(9)(i) are met.

Requirements in 10 CFR 51.22(c)(9)(ii)

    The proposed exemption would allow the use of Optimized ZIRLO\TM\ 
fuel rod cladding material in the reactors. Optimized ZIRLO\TM\ has 
essentially the same material properties and performance 
characteristics as the currently licensed ZIRLO[supreg] cladding. Thus, 
the use of Optimized ZIRLO\TM\ fuel rod cladding material will not 
significantly change the types of effluents that may be released 
offsite, or significantly increase the amount of effluents that may be 
released offsite. Therefore, the requirements of 10 CFR 51.22(c)(9)(ii) 
are met.

Requirements in 10 CFR 51.22(c)(9)(iii)

    The proposed exemption would allow the use of Optimized ZIRLO\TM\ 
fuel rod cladding material in the reactors. Optimized ZIRLO\TM\ has 
essentially the same material properties and performance 
characteristics as the currently licensed ZIRLO[supreg] cladding. Thus, 
the use of Optimized ZIRLO\TM\ fuel rod cladding material will not 
significantly increase individual occupational radiation exposure, or 
significantly increase cumulative occupational radiation exposure. 
Therefore, the requirements of 10 CFR 51.22(c)(9)(iii) are met.

IV. Conclusions

    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, is consistent with the common 
defense and security, and that special circumstances are present to 
warrant issuance of the exemption. Therefore, the Commission hereby 
grants Duke Energy an exemption from the requirements of 10 CFR 50.46 
and Appendix K, paragraph I.A.5 to 10 CFR part 50, to allow the 
application of these criteria to, and the use of, Optimized ZIRLO\TM\ 
fuel rod cladding material at MNS and CNS.
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 21st day of June 2016.

    For the Nuclear Regulatory Commission.
Anne T. Boland,
Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.
[FR Doc. 2016-15548 Filed 6-29-16; 8:45 am]
 BILLING CODE 7590-01-P