[Federal Register Volume 86, Number 209 (Tuesday, November 2, 2021)]
[Notices]
[Pages 60479-60481]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-23843]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-327 and 50-328; NRC-2021-0178]


Tennessee Valley Authority; Sequoyah Nuclear Plant, Units 1 and 2

AGENCY: Nuclear Regulatory Commission.

ACTION: Exemption; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) has issued an 
exemption in response to a September 23, 2020, request from the 
Tennessee Valley Authority to allow for the use of Optimized 
ZIRLOTM fuel rod cladding at Sequoyah Nuclear Plant, Units 1 
and 2.

DATES: The exemption was issued on October 26, 2021.

ADDRESSES: Please refer to Docket ID NRC-2021-0178 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 Website: Go to https://www.regulations.gov and search for Docket ID NRC-2021-0178. Address 
questions about Docket IDs in Regulations.gov to Stacy Schumann; 
telephone: 301-415-0624; email: [email protected]. For technical 
questions, contact the individual listed in the FOR FURTHER INFORMATION 
CONTACT section of this document.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly available documents online in the 
ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``Begin Web-based ADAMS 
Search.'' For problems with ADAMS, contact the NRC's Public Document 
Room (PDR) reference staff at 1-800-397-4209, 301-415-4737, or by email 
to [email protected]. For the convenience of the reader, 
instructions about obtaining materials referenced in this document are 
provided in the ``Availability of Documents'' section.
     Attention: The PDR, where you may examine and order copies 
of public documents, is currently closed. You may submit your request 
to the PDR via email at [email protected] or call 1-800-397-4209 or 
301-415-4737, between 8:00 a.m. and 4:00 p.m. (ET), Monday through 
Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Perry Buckberg, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: 301-415-1383, email: [email protected].

SUPPLEMENTARY INFORMATION: The text of the exemption is attached.

    Dated: October 28, 2021.

    For the Nuclear Regulatory Commission.
Perry H. Buckberg,
Senior Project Manager, Plant Licensing Branch II-2, Division of 
Operating Reactor Licensing, Office of Nuclear Reactor Regulation.

Attachment--Exemption

NUCLEAR REGULATORY COMMISSION

Docket Nos. 50-327 and 50-328

Tennessee Valley Authority, Sequoyah Nuclear Plant, Units 1 and 2 
Exemption

I. Background

    The Tennessee Valley Authority (TVA) is the holder of Renewed 
Facility Operating License Nos. DPR-77 and DPR-79, which authorize 
operation of Sequoyah Nuclear Plant, Units 1 and 2 (Sequoyah). The 
licenses provide, among other things, that the facilities are subject 
to all rules, regulations, and orders of the NRC now, or hereafter, in 
effect. The Sequoyah units are pressurized-water reactors located in 
Hamilton County, Tennessee, approximately 9.5 miles northeast of 
Chattanooga. TVA plans to use fuel rods with Optimized ZIRLO\TM\ 
cladding. Optimized ZIRLO cladding was developed to provide enhanced 
corrosion resistance in more adverse in-reactor primary chemistry 
environments and at higher fuel duties with higher burnups.

II. Request/Action

    By letter dated September 23, 2020, TVA requested an exemption from 
title 10 of the Code of Federal Regulations (10 CFR) section 50.46, 
``Acceptance criteria for emergency core cooling systems [ECCS] for 
light-water nuclear power reactors,'' and 10 CFR part 50, appendix K, 
``ECCS Evaluation Models,'' to allow the use of Optimized ZIRLO fuel 
rod cladding for future core reload applications. The regulations in 10 
CFR 50.46 contain acceptance criteria for the ECCS for reactors fueled 
with zircaloy or ZIRLO[supreg] fuel rod cladding material. In addition, 
paragraph I.A.5 of 10 CFR part 50,

[[Page 60480]]

appendix K, 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 
presumes the use of zircaloy or ZIRLO cladding material. Therefore, an 
exemption to 10 CFR 50.46 and 10 CFR part 50, appendix K, was requested 
to support the use of Optimized ZIRLO fuel rod cladding at Sequoyah.
    The exemption request relates solely to the specific types of 
cladding material specified in these regulations for use in light-water 
reactors (i.e., fuel rods with zircaloy or ZIRLO cladding). This 
request will provide for the application of the acceptance criteria of 
10 CFR 50.46 and 10 CFR part 50, appendix K, to fuel assembly designs 
using Optimized ZIRLO fuel rod cladding.

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: (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. Under 10 CFR 50.12(a)(2), 
special circumstances include, among other things, when application of 
the specific regulation in the particular circumstance would not serve, 
or is not necessary to achieve, the underlying purpose of the rule.
    The Optimized ZIRLO fuel cladding is different from standard ZIRLO 
in two respects: (1) The tin content is lower and (2) the 
microstructure is different. This difference in tin content and 
microstructure can lead to differences in some material properties. 
Westinghouse Electric Company (Westinghouse), the manufacturer of 
Optimized ZIRLO fuel rod cladding, has provided irradiated data and 
validate fuel performance models ahead of burnups achieved in batch 
application (i.e., a group of fuel assemblies).
    The NRC staff's safety evaluation dated June 10, 2005, related to 
Optimized ZIRLO, which is included as Addendum 1 of Westinghouse 
topical report WCAP-12610-P-A & CENPD-404-P-A, included ten conditions 
and limitations. The NRC staff reviewed TVA's exemption request found 
in enclosure 5 of TVA's letter dated September 23, 2020, and enclosure 
1, attachment 8 of the same letter, which addresses the licensee's 
compliance with each of the ten conditions and limitations. Based on 
its review, the NRC staff determined that the licensee satisfied all 
applicable conditions and limitations. The NRC staff evaluation of how 
the licensee addressed each of the ten conditions and limitations may 
be found in Section 3.8.10 of the staff Safety Evaluation related to 
Amendment Nos. 356 and 349 to Renewed Facility Operating License Nos. 
DPR-77 and DPR-79 for Sequoyah, dated October 26, 2021, which 
authorizes the transition to Westinghouse RFA-2 fuel.

A. The Exemption Is Authorized by Law

    This exemption would allow the use of Optimized ZIRLO fuel rod 
cladding material at Sequoyah. As stated above, 10 CFR 50.12 allows the 
NRC to grant exemptions from the requirements of 10 CFR part 50, 
provided, among other things, it finds that special circumstances are 
present. As described here and in the sections below, the NRC staff 
makes the requisite exemption findings. The fuel that will be 
irradiated at Sequoyah contains cladding material that differs from the 
cladding material that is explicitly defined in 10 CFR 50.46 and 
implicitly defined in 10 CFR part 50, appendix K. However, the criteria 
of these regulations will continue to be satisfied for the operation of 
the Sequoyah cores containing Optimized ZIRLO fuel cladding. The NRC 
staff has determined that granting the licensee's proposed exemption 
would not result in a violation of the Atomic Energy Act of 1954, as 
amended, other laws, or the Commission's regulations. Therefore, the 
exemption is authorized by law.

B. The Exemption Presents No Undue Risk to Public Health and Safety

    The NRC-approved Optimized ZIRLO topical report, WCAP-12610-P-A & 
CENPD-404-P-A, Addendum 1-A, has demonstrated that predicted chemical, 
thermal, and mechanical characteristics of the Optimized ZIRLO-alloy 
cladding are bounded by those approved for ZIRLO under anticipated 
operational occurrences and postulated accidents. The report 
demonstrates an acceptable retention of post-quench ductility up to 
2200 degrees Fahrenheit and oxidation of not more than 17 percent 
cladding thickness within 10 CFR 50.46 limits. Reload cores are 
required to be operated in accordance with the operating limits 
specified in the TSs and core operating limits report. Thus, the 
granting of this exemption request will not pose an undue risk to 
public health and safety.

C. The Exemption Is Consistent With the Common Defense and Security

    The exemption request would allow the licensee to use an improved 
fuel rod cladding material. In its letter dated September 23, 2020, the 
licensee stated that all the requirements and acceptance criteria will 
be maintained. Therefore, the use of Optimized ZIRLO-clad fuel rods 
will not adversely affect plant operations. Further, the licensee is 
required to handle and control special nuclear material in these 
assemblies in accordance with its approved procedures. Therefore, the 
NRC staff determined that this exemption does not adversely impact 
common defense and security.

D. Special Circumstances

    Special circumstances, in accordance with Sec.  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 purposes of 10 CFR 50.46 and 10 CFR part 50, 
appendix K, are to establish acceptance criteria for ECCS performance. 
The underlying purpose of the rule to maintain post-quench ductility in 
the fuel cladding material through ECCS performance criteria, and to 
ensure that analyses of fuel response are conservatively calculated, 
will continue to be achieved through the application of 10 CFR 50.46 
and 10 part 50, appendix K, to the new cladding. The regulations ensure 
that nuclear power reactors fueled with uranium oxide pellets within 
zircaloy or ZIRLO cladding must be provided with an ECCS designed to 
provide core cooling following postulated loss-of-coolant accidents. 
Westinghouse demonstrated in its NRC-approved topical report WCAP-
12610-P-A & CENPD-404-P-A Addendum 1-A that ECCS effectiveness will not 
be adversely affected by a change from zircaloy or ZIRLO clad fuel to 
Optimized ZIRLO clad fuel. The Westinghouse analysis also demonstrated 
that the ECCS acceptance criteria applied to reactors with fuel in 
zircaloy or ZIRLO fuel rod cladding are also applicable to reactors 
fueled with Optimized ZIRLO clad fuel. Normal safety analyses performed 
prior to core reload will confirm that there is no adverse impact on 
ECCS performance. Therefore, because the underlying purposes of 10 CFR 
50.46 and 10 CFR part 50, appendix K, are achieved through the use of 
Optimized ZIRLO fuel rod cladding material, the special circumstances 
required by 10 CFR 50.12(a)(2)(ii) for the granting of an exemption 
exist.

E. Environmental Considerations

    In 10 CFR 51.22, the Commission determined that certain NRC actions 
are eligible for categorical exclusion from the requirement to prepare 
an

[[Page 60481]]

environmental assessment or an environmental impact statement because 
each action category does not individually or cumulatively have a 
significant effect on the human environment.
    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 the granting of this 
exemption involves: (1) No significant hazards consideration [NSHC], 
(2) no significant change in the types or a significant increase in the 
amounts of any effluents that may be released offsite, and (3) no 
significant increase in individual or cumulative occupational radiation 
exposure. Therefore, in accordance with Sec.  51.22(b), no 
environmental impact statement or environmental assessment need be 
prepared in connection with the NRC staff's consideration of this 
exemption request. The basis for the NRC staff's determination is in 
the licensee's discussion of the 10 CFR 51.22(c)(9) criteria in the 
associated LAR noticed in the Federal Register on December 1, 2020 (85 
FR 77265). In addition, because Optimized ZIRLO cladding has 
essentially the same material properties and performance 
characteristics, and is adequately controlled by 10 CFR 50.46 and 10 
CFR part 50, appendix K.I.A.5, the use of Optimized ZIRLO will not 
significantly increase the types or amounts of effluents that may be 
released offsite, significantly increase individual occupational 
radiation exposure, or significantly increase cumulative occupational 
radiation exposure. Therefore, pursuant to 10 CFR 51.22(b), no 
environmental impact statement or environmental assessment need be 
prepared in connection with the NRC staff's consideration of this 
exemption request.

IV. Availability of Documents

    The documents identified in the following table are available to 
interested persons through one or more of the following methods, as 
indicated.

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                Document                       ADAMS  accession No.
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TVA, ``Application to Modify the          ML20267A617
 Sequoyah Nuclear Plant Units 1 and 2
 Technical Specification to Allow for
 Transition to Westinghouse RFA-2 Fuel
 (SQN-TS-20-09)'' (September 23, 2020).
Westinghouse, ``Final Safety Evaluation   ML051670395
 for Addendum 1 to Topical Report WCAP-
 12610-P-A & CENPD-404-P-A Addendum 1-A,
 `Optimized ZIRLO' '' (June 10, 2005).
NRC Safety Evaluation related to          ML21245A267
 Amendment Nos. 356 and 349 to Renewed
 Facility Operating License Nos. DPR-77
 and DPR-79 for Tennessee Valley
 Authority Sequoyah Nuclear Plant, Units
 1 and 2, Docket Nos. 50 327 And 50 328
 (October 26, 2021).
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V. Conclusions

    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 TVA an exemption from 10 CFR 
50.46 and 10 CFR part 50, appendix K paragraph I.A.5, to allow for the 
use of Optimized ZIRLO fuel rod cladding material at Sequoyah.

    Dated this 26 day of October, 2021.

    For the Nuclear Regulatory Commission.
Bo M. Pham,

Director, Division of Operating Reactor Licensing, Office of Nuclear 
Reactor Regulation.

[FR Doc. 2021-23843 Filed 11-1-21; 8:45 am]
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