[Federal Register Volume 75, Number 245 (Wednesday, December 22, 2010)]
[Notices]
[Pages 80549-80551]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-32141]
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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-346; NRC-2010-0378]
FirstEnergy Nuclear Operating Company, Davis-Besse Nuclear Power
Station; Exemption
1.0 Background
FirstEnergy Nuclear Operating Company (FENOC, the licensee) is the
holder of Facility Operating License No. NFP-3, which authorizes
operation of the Davis-Besse Nuclear Power Station, Unit 1 (DBNPS). 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
Ottawa County, Ohio.
2.0 Request/Action
Title 10 of the Code of Federal Regulations (10 CFR), Part 50,
Appendix G requires that fracture toughness requirements for ferritic
materials of pressure-retaining components of the reactor coolant
pressure boundary of light-water nuclear power reactors provide
adequate margins of safety during any condition of normal operation,
including anticipated operational occurrences and system hydrostatic
tests, to which the pressure boundary may be subjected over its service
lifetime; and Section 50.61 provides fracture toughness requirements
for protection against pressurized thermal shock (PTS) events. By
letter dated April 15, 2009, (Agencywide Documents Access and
Management System (ADAMS) Accession No. ML091130228), as supplemented
by letters dated December 18, 2009, (ADAMS Accession No. ML093570103)
and October 8, 2010 (ADAMS Accession No. ML102861221), FENOC proposed
exemptions from the requirements of 10 CFR Part 50, Appendix G and 10
CFR 50.61, to revise certain DBNPS reactor pressure vessel (RPV)
initial (unirradiated) properties using Framatome Advanced Nuclear
Power Topical Report (TR) BAW-2308, Revisions 1A and 2A, ``Initial
RTNDT of Linde 80 Weld Materials.''
The licensee requested an exemption from Appendix G to 10 CFR Part
50 to replace the required use of the existing Charpy V-notch
(Cv) and drop weight-based methodology and allow the use of
an alternate methodology to incorporate the use of fracture toughness
test data for evaluating the integrity of the DBNPS RPV circumferential
beltline welds based on the use of the 1997 and 2002 editions of
American Society for Testing and Materials (ASTM) Standard Test Method
E 1921, ``Standard Test Method for Determination of Reference
Temperature T0, for Ferritic Steels in the Transition
Range,'' and American Society for Mechanical Engineering (ASME), Boiler
and Pressure Vessel Code (Code), Code Case N-629, ``Use of Fracture
Toughness Test Data to establish Reference Temperature for Pressure
Retaining materials of Section III, Division 1, Class 1.'' The
exemption is required since Appendix G to 10 CFR Part 50, through
reference to Appendix G to Section XI of the ASME Code
[[Page 80550]]
pursuant to 10 CFR 50.55(a), requires the use of a methodology based on
Cv and drop weight data.
The licensee also requested an exemption from 10 CFR 50.61 to use
an alternate methodology to allow the use of fracture toughness test
data for evaluating the integrity of the DBNPS RPV circumferential
beltline welds based on the use of the 1997 and 2002 editions of ASTM E
1921 and ASME Code Case N-629. The exemption is required since the
methodology for evaluating RPV material fracture toughness in 10 CFR
50.61 requires the use of the Cv and drop weight data for
establishing the PTS reference temperature (RTPTS).
3.0 Discussion of Exemption
Pursuant to 10 CFR 50.12(a), 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, are consistent with the common defense and security; and (2)
when special circumstances are present. These circumstances include the
special circumstances that allow the licensee an exemption from the use
of the Cv and drop weight-based methodology required by 10
CFR Part 50, Appendix G and 10 CFR 50.61. These exemptions only modify
the methodology to be used by the licensee for demonstrating compliance
with the requirements of 10 CFR Part 50, Appendix G and 10 CFR 50.61,
and does not exempt the licensee from meeting any other requirement of
10 CFR Part 50, Appendix G and 10 CFR 50.61.
Authorized by Law
These exemptions would allow the licensee to use an alternate
methodology to make use of fracture toughness test data for evaluating
the integrity of the DBNPS RPV beltline welds, and would not result in
any changes to the operation of the plant. Section 50.60(b) of 10 CFR
Part 50 allows the use of alternatives to 10 CFR Part 50, Appendix G,
or portions thereof, when an exemption is granted by the Commission
under 10 CFR 50.12. In addition, Section 50.60(b) of 10 CFR Part 50
permits different NRC-approved methods for use in determining the
initial material properties. As stated above, 10 CFR 50.12(a) allows
the NRC to grant exemptions from the requirements of 10 CFR Part 50,
Appendix G and 10 CFR 50.61. The NRC staff has determined that granting
of the licensee's proposed exemptions will not result in a violation of
the Atomic Energy Act of 1954, as amended, or the Commission's
regulations. Therefore, the exemptions are authorized by law.
No Undue Risk to Public Health and Safety
The underlying purpose of Appendix G to 10 CFR Part 50 is to set
forth fracture toughness requirements for ferritic materials of
pressure-retaining components of the reactor coolant pressure boundary
of light-water nuclear power reactors to provide adequate margins of
safety during any condition of normal operation, including anticipated
operational occurrences and system hydrostatic tests, to which the
pressure boundary may be subjected over its service lifetime. The
methodology underlying the requirements of Appendix G to 10 CFR Part 50
is based on the use of Cv and drop weight data. The licensee
proposes to replace the use of the existing Cv and drop
weight-based methodology by a fracture toughness-based methodology to
demonstrate compliance with Appendix G to 10 CFR Part 50. The NRC staff
has concluded that the exemptions are justified based on the licensee
utilizing the fracture toughness methodology specified in BAW-2308,
Revisions 1A and 2A, within the conditions and limitations delineated
in the NRC staff's safety evaluations (SEs), dated August 4, 2005
(ADAMS Accession No. ML052070408) and March 24, 2008 (ADAMS Accession
No. ML080770349). The use of the methodology specified in the NRC
staff's SEs will ensure that pressure-temperature limits developed for
the DBNPS RPV will continue to be based on an adequately conservative
estimate of RPV material properties and ensure that the pressure-
retaining components of the reactor coolant pressure boundary retain
adequate margins of safety during any condition of normal operation,
including anticipated operational occurrences. This exemption only
modifies the methodology to be used by the licensee for demonstrating
compliance with the requirements of Appendix G to 10 CFR Part 50, and
does not exempt the licensee from meeting any other requirement of
Appendix G to 10 CFR Part 50.
The underlying purpose of 10 CFR 50.61 is to establish requirements
for evaluating the fracture toughness of RPV materials to ensure that a
licensee's RPV will be protected from failure during a PTS event. The
licensee seeks an exemption from 10 CFR 50.61 to use a methodology for
the ``determination of adjusted/indexing reference temperatures.'' The
licensee proposes to use ASME Code Case N-629 and the methodology
outlined in its submittal, which are based on the use of fracture
toughness data, as an alternative to the Cv and drop weight-
based methodology required by 10 CFR 50.61 for establishing the
initial, unirradiated properties when calculating RTPTS
values. The NRC staff has concluded that the exemption is justified
based on the licensee utilizing the methodology specified in the NRC
staff's SE regarding TR BAW-2308, Revisions 1-A and 2-A, dated August
4, 2005, and March 24, 2008, respectively. This TR established an
alternative method for determining initial (unirradiated) material
reference temperatures for RPV welds manufactured using Linde 80 weld
flux (i.e., ``Linde 80 welds'') and established weld wire heat-specific
and Linde 80 weld generic values of this reference temperature. These
weld wire heat-specific and Linde 80 weld generic values may be used in
lieu of the nil-ductility reference temperature (RTNDT)
parameter, the determination of which is specified by paragraph NB-2331
of Section III of the ASME Code. Regulations associated with the
determination of RPV material properties involving protection of the
RPV from brittle failure or ductile rupture include Appendix G to 10
CFR Part 50 and 10 CFR 50.61, the PTS rule. These regulations require
that the initial (unirradiated) material reference temperature,
RTNDT, be determined in accordance with the provisions of
the ASME Code, and provide the process for determination of
RTPTS, the reference temperature RTNDT, evaluated
for the end of license fluence.
In TR BAW-2308, Revision 1, the Babcock and Wilcox Owners Group
proposed to perform fracture toughness testing based on the application
of the Master Curve evaluation procedure, which permits data obtained
from sample sets tested at different temperatures to be combined, as
the basis for redefining the initial (unirradiated) material properties
of Linde 80 welds. NRC staff evaluated this methodology for determining
Linde 80 weld initial (unirradiated) material properties and
uncertainty in those properties, as well as the overall method for
combining unirradiated material property measurements based on NRC-
accepted values of initial (unirradiated) reference temperature
(IRTTo), with property shifts from models in Regulatory
Guide (RG) 1.99, Revision 2, ``Radiation Embrittlement of Reactor
Vessel Materials,'' which are based on Cv testing and a
defined margin term to account for uncertainties in the NRC
[[Page 80551]]
staff SE. Table 3 in the staff's August 4, 2005, SE of BAW-2308,
Revision 1, contains the NRC staff-accepted IRTTO and
corresponding initial uncertainty term, [sigma]I, for
specific Linde 80 weld wire heat numbers. In accordance with the
conditions and limitations outlined in the NRC staff's August 4, 2005
SE of TR BAW-2308, Revision 1, for utilizing the values in Table 3, the
licensee's proposed methodology (1) utilized the appropriate NRC staff-
accepted IRTTo and [sigma]I values for Linde 80
weld wire heat numbers; (2) applied the appropriate chemistry factors
for temperatures greater than 167 [deg]F (the weld wire heat-specific
chemical composition, via the methodology of RG 1.99, Revision 2,
indicated that higher chemistry factors are applicable); (3) applied a
value of 28 [deg]F for [sigma][Delta] in the margin term;
and (4) submitted values for [Delta]RTNDT and the margin
term for each Linde 80 weld in the RPV through the end of the current
operating license. Additionally, the NRC's SE for TR BAW-2308, Revision
2, concludes that the revised IRTT0 and [sigma]I
values for Linde 80 weld materials are acceptable for referencing in
plant-specific licensing applications as delineated in TR BAW-2308,
Revision 2, and to the extent specified under Section 4.0, Limitations
and Conditions, of the SE, which states: ``Future plant-specific
applications for RPVs containing weld heat 72105, and weld heat 299L44,
of Linde 80 welds must use the revised IRTT0 and
[sigma]I, values in TR BAW-2308, Revision 2.'' The staff
notes that neither of these weld heats is used at DBNPS. Therefore, all
conditions and limitations outlined in the NRC staff SEs for TR BAW-
2308, Revisions 1-A and 2-A, have been met for DBNPS.
The use of the methodology in TR BAW-2308, Revision 1, will ensure
the PTS evaluation developed for the DBNPS RPV will continue to be
based on an adequately conservative estimate of RPV material properties
and ensure the RPV will be protected from failure during a PTS event.
Also, when additional fracture toughness data relevant to the
evaluation of the DBNPS RPV welds is acquired as part of the
surveillance program, this data must be incorporated into the
evaluation of the DBNPS RPV fracture toughness requirements.
Based on the above, no new accident precursors are created by
allowing an exemption to use an alternate methodology to comply with
the requirements of 10 CFR 50.61 in determining adjusted/indexing
reference temperatures, 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. On February 3, 2010, a new rule, 10
CFR 50.61a, ``Alternate Fracture Toughness Requirements for Protection
Against PTS Events,'' became effective. The NRC staff reviewed this new
rule against the licensee's exemption request and determined that there
is no effect on the exemption request. The new rule does not modify the
requirements from which the licensee has sought an exemption, and the
alternative provided by the new rule does not address the scope of
issues associated with both 10 CFR 50.61 and 10 CFR Part 50, Appendix G
that the requested exemption does.
Consistent With Common Defense and Security
The proposed exemption would allow the licensee to use an alternate
methodology to allow the use of fracture toughness test data for
evaluating the integrity of the DBNPS RPV beltline welds. This change
has no relation to security issues. Therefore, the common defense and
security is not impacted by these exemptions.
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 Part 50, Appendix G and 10 CFR
50.61 is to protect the integrity of the reactor coolant pressure
boundary by ensuring that each reactor vessel material has adequate
fracture toughness. Therefore, since the underlying purpose of 10 CFR
Part 50, Appendix G and 10 CFR 50.61 is achieved by an alternative
methodology for evaluating RPV material fracture toughness, the special
circumstances required by 10 CFR 50(a)(2)(ii) for the granting of an
exemption from portions of the requirements of 10 CFR Part 50, Appendix
G and 10 CFR 50.61 exist.
4.0 Conclusion
The staff has reviewed the licensee's submittals and concludes that
the licensee has provided adequate justification for its request for an
exemption from certain requirements of Appendix G to 10 CFR Part 50 and
10 CFR 50.61, to allow an alternative methodology that is based on
using fracture toughness test data to determine initial, unirradiated
properties for evaluating the integrity of the DBNPS RPV beltline
welds.
Accordingly, the Commission has determined that pursuant to 10 CFR
50.12, ``Specific exemptions,'' an exemption from certain requirements
of Appendix G to 10 CFR Part 50 and 10 CFR 50.61 is authorized by law
and will not endanger life or property or the common defense and
security, and is otherwise in the public interest.
Pursuant to 10 CFR 51.32, ``Finding of no significant impact,'' the
Commission has previously determined that the granting of this
exemption will not have a significant effect on the quality of the
human environment (75 FR 76498).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 14th day of December 2010.
For the Nuclear Regulatory Commission.
Joseph G. Giitter,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. 2010-32141 Filed 12-21-10; 8:45 am]
BILLING CODE 7590-01-P