[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]
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