[Federal Register Volume 81, Number 123 (Monday, June 27, 2016)]
[Notices]
[Pages 41605-41608]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-15144]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. STN 50-456, STN 50-457, STN 50-454 and STN 50-455; NRC-
2016-0124]


Exelon Generation Company, LLC; Braidwood Station, Units 1 and 2, 
and Byron Station, Unit Nos. 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 February 23, 2016, request from Exelon 
Generation Company, LLC, requesting an exemption to allow use of a 
different fuel rod cladding material (Optimized ZIRLOTM).

ADDRESSES: Please refer to Docket ID NRC-2016-0124 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-2016-0124. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; 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 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: Joel S. Wiebe, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington DC 
20555-0001; telephone: 301-415-6606, email: [email protected].

SUPPLEMENTARY INFORMATION: 

I. Background

    Exelon Generation Company, LLC (Exelon or the licensee) is the 
holder of renewed Facility Operating License Nos. STN 50-456, STN 50-
457, STN 50-454 and STN 50-455, which authorize operation of the 
Braidwood Station (Braidwood), Units 1 and 2, and the Byron Station 
(Byron) Unit Nos. 1 and 2, respectively. The license provides, among 
other things, that the facility is subject to all rules, regulations, 
and orders of the NRC now or hereafter in effect.
    The Braidwood facility consists of two pressurized-water reactors 
located in Will County in Illinois and the Byron facility consists of 
two pressurized-water reactors located in Ogle County in Illinois.

II. Request/Action

    Pursuant to section 50.12 of title 10 of the Code of Federal 
Regulations (10 CFR), ``Specific exemptions,'' the licensee has, by 
letter dated February 23, 2016 (ADAMS Accession No. ML16055A149), 
requested an exemption from 10 CFR 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 fuel rod cladding with Optimized ZIRLOTM 
alloy for future reload applications. The regulations in 10 CFR 50.46 
contain acceptance criteria for the ECCS for reactors fueled with 
zircaloy or ZIRLOTM fuel rod cladding material. In addition, 
paragraph I.A.5 of appendix K to 10 CFR part 50 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 a zirconium alloy, 
which is a material different from Optimized ZIRLOTM. Thus, 
the strict application of these regulations does not permit the use of 
fuel rod cladding material other than zircaloy or ZIRLOTM. 
Because the material specifications of Optimized ZIRLOTM 
differ from the specifications for zircaloy or ZIRLOTM, and 
the regulations specify a cladding material other than Optimized 
ZIRLOTM, a plant-specific exemption is required to allow the 
use of, and application of these regulations to, Optimized 
ZIRLOTM at Braidwood and Byron Stations.
    The exemption request relates solely to the cladding material 
specified in these regulations (i.e., fuel rods with zircaloy or 
ZIRLOTM cladding material). This exemption would allow 
application of the acceptance criteria of 10 CFR 50.46 and 10 CFR part 
50, appendix K, to fuel assembly designs using Optimized 
ZIRLOTM fuel rod cladding material. In its letter dated 
February 23, 2016, the licensee indicated that it was not seeking an 
exemption from the acceptance and analytical criteria of these 
regulations. The intent of the request is to allow the use of the 
criteria set forth in these regulations for the use of Optimized 
ZIRLOTM fuel rod cladding material at Braidwood and Byron 
Stations.

[[Page 41606]]

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)(ii), 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.

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 reasonable assurance of safety in the event of a loss-of-
coolant accident (LOCA). Although the regulations in 10 CFR 50.46 and 
appendix K are not expressly applicable to Optimized ZIRLO\TM\, 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 correlation 
conservatively bounds LOCA scenario metal-water reaction rates and is 
applicable to Optimized ZIRLO\TM\. Thus, a strict application of the 
rule (which would preclude the applicability of ECCS performance 
acceptance criteria to, and the use of, Optimized ZIRLO\TM\ fuel 
cladding material) is not necessary to achieve the underlying purposes 
of 10 CFR 50.46 and appendix K to 10 CFR part 50. The purpose of these 
regulations is achieved through application of the specific 
requirements to use the Optimized ZIRLO\TM\ fuel rod cladding material. 
Therefore, the special circumstances required by 10 CFR 50.12(a)(2)(ii) 
for the granting of an exemption exist.

Authorized by Law

    This exemption would allow the use of Optimized ZIRLO\TM\ fuel rod 
cladding material for future reload operations at Braidwood and Byron 
Stations. As stated above, 10 CFR 50.12 allows the NRC to grant 
exemptions from the requirements of 10 CFR part 50 provided that 
special circumstances are present. As described above, the NRC staff 
has determined that special circumstances exist to grant the requested 
exemption. In addition, granting the 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

    Section 10 CFR 50.46 requires that each boiling or pressurized 
light-water nuclear power reactor fueled with uranium dioxide pellets 
within cylindrical zircaloy or ZIRLO\TM\ cladding must be provided with 
an ECCS that must be designed so that its calculated cooling 
performance following a postulated LOCA conforms to the criteria set 
forth in paragraph (b) of section 10 CFR 50.46. 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 safety 
evaluation dated June 10, 2005 (ADAMS Accession No. ML051670395), 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 found that Westinghouse 
demonstrated the applicability of these ECCS acceptance criteria to 
Optimized ZIRLOTM. Ring compression tests performed by 
Westinghouse on Optimized ZIRLOTM (see WCAP-14342-A & CENPD-
404-NP-A at ADAMS Accession No. ML062080569) demonstrate an acceptable 
retention of post-quench ductility up to 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 the 
licensee in letter LTR-NRC-07-58 from Westinghouse to the NRC, ``SER 
Compliance with WCAP-12610-P-A & CENPD-404-P-A, Addendum 1-A, 
`Optimized ZIRLOTM,' '' dated November 6, 2007 (public 
version located at ADAMS Accession No. ML073130560), illustrate that 
oxide thickness and associated hydrogen pickup for Optimized 
ZIRLOTM at any given burnup would be less than both 
zircaloy-4 and ZIRLOTM. Hence, the NRC staff concludes that 
Optimized ZIRLOTM would be expected to maintain better post-
quench ductility than ZIRLOTM. This finding is further 
supported by an ongoing LOCA research program at Argonne National 
Laboratory, which has identified a strong correlation between cladding 
hydrogen content (caused by in-service corrosion) and postquench 
ductility.
    Westinghouse, in letters dated January 4, 2007 (ADAMS Accession 
Nos. ML070100385 and ML070100388), November 6, 2007 (ADAMS Accession 
Nos. ML073130556 and ML073130560), December 30, 2008 (ADAMS Accession 
Nos. ML080390451 and ML080390452), February 5, 2009 (ADAMS Accession 
Nos. ML090080380 and ML090080381), July 26, 2010 (ADAMS Accession Nos. 
ML102140213 and ML102140214), February 25, 2013 (ADAMS Accession Nos. 
ML13070A188 and ML13070A189), and February 9, 2015 (ADAMS Accession 
Nos. ML15051A427 and ML15051A429), provided information that confirmed 
the models' applicability for burnups up to 62 GWD/MTU for Westinghouse 
fuels.
    In addition, the provisions of 10 CFR 50.46 require the licensee to 
periodically evaluate the performance of the ECCS, using currently 
approved LOCA models and methods, to ensure that the fuel rods will 
continue to satisfy 10 CFR 50.46 acceptance criteria. In its letter 
dated February 23, 2016, the licensee stated that it will evaluate fuel 
assemblies using Optimized ZIRLO\TM\ fuel rod cladding material using 
NRC-approved methods and models to address the use of Optimized 
ZIRLO\TM\ fuel rod cladding. The NRC staff concludes that granting the 
exemption to allow the licensee to use Optimized ZIRLO\TM\ fuel rod 
cladding material and apply 10 CFR 50.46 criteria would not diminish 
this requirement of periodic evaluation of ECCS performance. Thus, the 
underlying purpose of the rule to maintain post-quench ductility in the 
fuel cladding material through ECCS performance criteria will continue 
to be achieved for Braidwood and Byron Stations.
    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 this provision of the rule would not 
permit use of the equation for Optimized ZIRLOTM fuel rod 
cladding material for determining acceptable fuel performance. The 
underlying purpose of this regulation, however, is to ensure that 
analyses of fuel response to LOCAs are conservatively calculated. In 
its evaluation of the approved topical reports, the NRC staff 
previously found

[[Page 41607]]

that metal-water reaction tests performed by Westinghouse on Optimized 
ZIRLOTM (see Appendix B of WCAP-12610-P-A and CENPD-404-P-A, 
Addendum 1-A) demonstrate conservative reaction rates relative to the 
Baker-Just equation, and that the Baker-Just equation conservatively 
bounds post-LOCA scenarios of, and applicable to, Optimized 
ZIRLOTM fuel rod cladding. Thus, the NRC staff determined 
that the strict application of Appendix K, Paragraph I.A.5 (which would 
preclude its applicability to, and the use of, Optimized 
ZIRLOTM) is not necessary to achieve the underlying purpose 
of the rule in these circumstances. Since these evaluations demonstrate 
that the underlying purpose of the rule will be met, there will be no 
undue risk to the public health and safety.

Consistent With the Common Defense and Security

    The licensee's exemption request is to allow the application of an 
improved fuel rod cladding material to the regulations in 10 CFR 50.46 
and paragraph I.A.5 of appendix K to 10 CFR part 50. In its letter 
dated February 23, 2016, the licensee stated that all the requirements 
and acceptance criteria will be maintained. The licensee is required to 
handle and control special nuclear material in these assemblies in 
accordance with its approved procedures. This change to reactor core 
internals is adequately controlled by NRC requirements and is not 
related to security issues. Therefore, the NRC staff determined that 
this exemption does not impact, and thus 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) through (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 exemption would allow the use of Optimized ZIRLO\TM\ 
fuel rod cladding material in the reactors. The NRC approved topical 
report WCAP-12610-P-A and CENPD-404-P-A, Addendum 1-A ``Optimized 
ZIRLO\TM\,'' prepared by Westinghouse, addresses Optimized ZIRLO\TM\ 
and demonstrates that Optimized ZIRLO\TM\ has essentially the same 
properties as currently licensed ZIRLO[supreg]. The fuel cladding 
itself is not an accident initiator and does not affect accident 
probability. Use of Optimized ZIRLO\TM\ fuel cladding material will 
continue to meet all 10 CFR 50.46 acceptance criteria and, therefore, 
will not increase the consequences of an accident.
    Therefore, the proposed exemption 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 use of Optimized ZIRLO\TM\ fuel rod cladding material will not 
result in changes in the operation or configuration of the facility. 
Topical Reports WCAP-12610-P-A and CENPD-404-PA demonstrated that the 
material properties of Optimized ZIRLO\TM\ are similar to those of 
standard ZIRLO[supreg]. Therefore, Optimized ZIRLO\TM\ fuel rod 
cladding material will perform similarly to those fabricated from 
standard ZIRLO[supreg], thus precluding the possibility of the fuel 
cladding becoming an accident initiator and causing a new or different 
type of accident.
    Therefore, the proposed exemption does not create the possibility 
of a new or different kind of accident from any previously evaluated.
    3. Does the proposed exemption involve a significant reduction in a 
margin of safety?
    Response: No.
    The proposed exemption 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 standard ZIRLO[supreg] for all normal operating 
and accident scenarios, including both 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 will demonstrate that the 
acceptance criteria of 10 CFR 50.46 have been satisfied.
    Therefore, the proposed exemption does not involve a significant 
reduction in a margin of safety.
    Based on the above evaluation of the standards set forth in 10 CFR 
50.92(c), 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.

Conclusion

    Based on the above, the NRC staff concludes that the proposed 
exemption meets the eligibility criteria for the categorical exclusion 
set forth in 10 CFR 51.22(c)(9). Therefore, in accordance

[[Page 41608]]

with 10 CFR 51.22(b), no environmental impact statement or 
environmental assessment need be prepared in connection with the NRC's 
proposed issuance of this exemption.

IV. 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 pursuant to 10 CFR 
50.12(a)(2)(ii) are present. Therefore, the Commission hereby grants 
Exelon an exemption from the requirements of 10 CFR 50.46 and appendix 
K to 10 CFR part 50, to allow the application of those criteria to, and 
the use of, Optimized ZIRLO\TM\ fuel rod cladding material at the 
Braidwood Station, Units 1 and 2, and Byron Station Unit Nos. 1 and 2.
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 20th 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. 2016-15144 Filed 6-24-16; 8:45 am]
 BILLING CODE 7590-01-P