[Federal Register Volume 76, Number 214 (Friday, November 4, 2011)]
[Notices]
[Pages 68512-68514]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-28610]
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NUCLEAR REGULATORY COMMISSION
[NRC-2010-0062; Docket No. 50-261]
Carolina Power & Light Company; H. B. Robinson Steam Electric
Plant, Unit 2; Exemption
1.0 Background
Carolina Power & Light Company (the licensee) is the holder of
Renewed Facility Operating License No. DPR-23, which authorizes
operation of the H. B. Robinson Steam Electric Plant (HBRSEP), Unit 2.
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 New Hill,
North Carolina.
2.0 Request/Action
Title 10 of the Code of Federal Regulations (10 CFR), 50.46,
[[Page 68513]]
``Acceptance criteria for emergency core cooling systems for light-
water nuclear power reactors,'' paragraph (a)(1)(i) provides
requirements for reactors containing uranium oxide fuel pellets clad in
either zircaloy or ZIRLO. Additionally, Appendix K to 10 CFR part 50,
``ECCS [Emergency Core Cooling System] Evaluation Models,'' specifies
the use of zircaloy or ZIRLO fuel cladding when doing calculations for
energy release, cladding oxidation, and hydrogen generation after a
postulated loss-of-coolant accident. Therefore, both of these
regulations either state or assume that either zircaloy or ZIRLO is
used as the fuel rod cladding material.
By letter dated October 19, 2010 (Agencywide Documents Access and
Management System (ADAMS) Accession No. ML102980142), the licensee
requested an exemption from the requirements of 10 CFR 50.46 and
Appendix K to 10 CFR part 50 to allow the use of fuel rods clad with
AREVA's M5 alloy. The advanced zirconium-based M5 alloy is a
proprietary alloy and chemically different from zircaloy or ZIRLO fuel
cladding materials, which are approved for use. The exemption request
related solely to the specific types of cladding material specified in
these regulations. As written, the regulations presume the use of
zircaloy or ZIRLO fuel rod cladding. Thus, an exemption from the
requirements of 10 CFR 50.46 and Appendix K to 10 CFR part 50 is needed
to support transition to the AREVA fuel design with advanced zirconium-
based M5 alloy at HBRSEP Unit 2.
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. The requested exemption to
allow the use of M5 advanced zirconium alloy rather than zircaloy or
ZIRLO for fuel cladding material for reloads at HBRSEP, Unit 2,
satisfies these requirements as described below.
Authorized by Law
This exemption would allow the use of M5 advanced alloy, in lieu of
zircaloy or ZIRLO, for fuel rod cladding in fuel assemblies at HBRSEP,
Unit 2. 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 ECCS performance. In the approved topical report BAW-
10227(P)(A), Revision 1, ``Evaluation of Advanced Cladding and
Structural Material (M5) in PWR Reactor Fuel,'' dated June 18, 2003,
Framatome ANP demonstrated that the effectiveness of the ECCS will not
be affected by a change from zircaloy fuel rod cladding to M5 fuel rod
cladding. The analysis described in the topical report also
demonstrated that the ECCS acceptance criteria applied to reactors
fueled with zircaloy clad fuel are also applicable to reactors fueled
with M5 fuel rod cladding.
The NRC staff's review and approval of topical report BAW-
10227(P)(A), Revision1 addressed all of the important aspects of M5
with respect to ECCS performance requirements: (1) Applicability of 10
CFR 50.46(b) fuel acceptance criteria; (2) M5 material properties
including fuel rod ballooning and rupture strains; and (3) steam
oxidation kinetics and applicability of Baker-Just weight gain
correlation. A subsequent NRC-approved topical report, BAW-10240P-A,
``Incorporation of M5 Properties in Framatome ANP Approved Methods,''
further addressed M5 material properties with respect to the loss-of-
coolant accident (LOCA) applications.
Appendix K, paragraph I.A.5, of 10 CFR part 50 ensures that
cladding oxidation and hydrogen generation are appropriately limited
during a LOCA, and conservatively accounted for in the ECCS evaluation
model. Appendix K 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. In topical report BAW-10227(P)(A),
Revision 1, Framatome ANP demonstrated that the Baker-Just model is
conservative in the evaluated post-LOCA scenarios with respect to the
use of the M5 advanced alloy as a fuel rod cladding material, and that
the amount of hydrogen generated in an M5-clad core during a LOCA will
remain within the HBRSEP, Unit No. 2, design basis.
The M5 alloy is proprietary zirconium-based alloy comprised of
primarily zirconium (~99 percent) and niobium (~1 percent). The
elimination of tin has resulted in superior corrosion resistance and
reduced irradiation-induced growth relative to both standard zircaloy
(1.7 percent tin) and low-tin zircaloy (1.2 percent tin). The addition
of niobium increases ductility, which is desirable to avoid brittle
failures.
The NRC staff has reviewed the advanced cladding and structural
material, M5, for pressurized-water reactor fuel mechanical designs as
described in BAW-10227(P)(A), Revision 1. In the safety evaluation for
this topical report, the NRC staff concluded that, to the extent and
limitations specified in the staff's evaluation, the properties of M5
and mechanical design methodology are acceptable for referencing in
fuel reload licensing applications.
Based on the above, no new accident precursors are created by the
use of M5 fuel cladding at HBRSEP, Unit 2; 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.
Consistent With Common Defense and Security
The proposed exemption would allow the use of M5 advanced alloy, in
lieu of zircaloy or ZIRLO, for fuel rod cladding in fuel assemblies at
HBRSEP, Unit 2. The M5 fuel rod cladding is similar in design to the
current cladding material used at HBRSEP, Unit 2. This change in
cladding material will not result in any changes to the security
aspects associated with the control of special nuclear material. The
change in cladding material is unrelated to other security issues.
Therefore, the common defense and security is not impacted by this
exemption.
Special Circumstances
Special circumstances, in accordance with 10 CFR 50.12, 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 ensure that nuclear
power facilities have adequately demonstrated the cooling performance
of their ECCS. As discussed above, topical report BAW-10227(P)(A),
Revision 1 concluded that the effectiveness of the ECCS will not be
affected by a change from zircaloy fuel rod cladding to M5 fuel rod
cladding and also demonstrated that the ECCS acceptance criteria
[[Page 68514]]
applied to reactors fueled with zircaloy clad fuel are also applicable
to reactors fueled with M5 fuel rod cladding.
The underlying purpose of 10 CFR part 50, appendix K, paragraph
I.A.5 is to ensure that cladding oxidation and hydrogen generation are
appropriately limited during a LOCA and conservatively accounted for in
the ECCS evaluation model. Specifically, Appendix K 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. Topical Report BAW-10227(P)(A), Revision 1, demonstrated
that the Baker-Just model is conservative in the evaluated post-LOCA
scenarios with respect to the use of the M5 advanced alloy as a fuel
rod cladding material.
Based on the above, the underlying purpose of 10 CFR 50.46 and 10
CFR part 50, Appendix K is still met and literal compliance is not
necessary for use of M5 fuel rod cladding. Therefore, the special
circumstances required by 10 CFR 50.12 for the granting of an exemption
from 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 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 the licensee an exemption from
the requirements of 10 CFR 50.46 and Appendix K of 10 CFR part 50.
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 (October 26, 2011; 76 FR 6633). This
exemption is effective upon issuance.
Dated at Rockville, Maryland this 31st day of October 2011.
For the Nuclear Regulatory Commission.
Michele G. Evans,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. 2011-28610 Filed 11-3-11; 8:45 am]
BILLING CODE 7590-01-P