[Federal Register Volume 72, Number 127 (Tuesday, July 3, 2007)]
[Notices]
[Pages 36512-36514]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-12855]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-280 and 50-281]
Virginia Electric And Power Company Surry Power Station, Unit
Nos. 1 and 2; Exemption
1.0 Background
The Virginia Electric and Power Company (the licensee) is the
holder of Renewed Facility Operating License Nos. DPR-32 and DPR-37
which authorize operation of the Surry Power Station, Unit Nos. 1 and 2
(Surry 1 and 2). The license provides, among other things, that the
facility is subject to all rules, regulations, and orders of the
Nuclear Regulatory Commission (NRC, the Commission) now or hereafter in
effect.
The facility consists of two pressurized-water reactors located in
Surry County, Virginia.
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 need 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; and Section 50.61 provides fracture toughness
[[Page 36513]]
requirements for protection against pressurized thermal shock (PTS)
events. By letter dated June 13, 2006 (Agencywide Documents Access and
Management System (ADAMS) Accession No. ML061650080), Virginia Electric
and Power Company (Dominion) proposed exemptions from the requirements
of 10 CFR Part 50, Appendix G and 10 CFR 50.61, to revise certain Surry
1 and 2 reactor pressure vessel (RPV) initial (unirradiated) properties
using Framatome Advanced Nuclear Power Topical Report (TR) BAW-2308,
Revision 1, ``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 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 Surry 1 and 2 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 pursuant to 10 CFR 50.55(a), requires the use of a methodology
based on Charpy V-notch 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 Surry 1 and 2 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 Charpy V-notch and
drop weight data for establishing the PTS reference temperature
(RTPTS).
3.0 Discussion
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, and 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 Charpy V-notch and drop weight-based methodology required by
10 CFR Part 50, Appendix G and 10 CFR 50.61. This exemption only
modifies 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 Surry 1 and 2 RPV circumferential beltline welds,
and would not result in changes to 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 Charpy V-notch and drop weight data. The
licensee proposes to replace the use of the existing Charpy V-notch 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, Revision 1, within the conditions and limitations delineated in
the NRC staff's safety evaluation (SE), dated August 4, 2005 (ADAMS
Accession Number ML052070408). The use of the methodology specified in
the NRC staff's SE will ensure that P-T limits developed for the Surry
1 and 2 RPVs 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
which ensure that a licensee's RPV will be protected from failure
during a PTS event by evaluating the fracture toughness of RPV
materials. 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 Charpy V-notch 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, Revision 1, dated August 4, 2005.
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)
[[Page 36514]]
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
(B&WOG) 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 T0 values, property shifts from models
in regulatory guide (RG) 1.99, Revision 2, which are based on Charpy V-
notch testing and a defined margin term to account for uncertainties in
the NRC staff SE. Table 3 in the SE contains the NRC staff-accepted
IRTTO and initial margin (denoted as [sigma]i)
for specific Linde 80 weld wire heat numbers. In accordance with the
conditions and limitations outlined in the NRC staff SE on TR BAW-2308,
Revision 1, for utilizing the values in Table 3: the licensee has
utilized the appropriate NRC staff-accepted IRTT0 and
[sigma]i values for Linde 80 weld wire heat numbers; applied
a chemistry factor of 167 [deg]F (the weld wire heat-specific chemical
composition, via the methodology of RG 1.99, Revision 2, did not
indicate that a higher chemistry factor should apply); applied a value
of 28 [deg]F for [sigma][Delta] in the margin term; and 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.
Therefore, all conditions and limitations outlined in the NRC staff SE
on TR BAW-2308, Revision 1, have been met for Surry 1 and 2.
The use of the methodology in TR BAW-2308, Revision 1, will ensure
the PTS evaluation developed for the Surry 1 and 2 RPVs will continue
to be based on an adequately conservative estimate of RPV material
properties and ensure the RPVs will be protected from failure during a
PTS event. Also, when additional fracture toughness data relevant to
the evaluation of the Surry 1 and 2 RPV circumferential welds is
acquired as part of the surveillance program, this data must be
incorporated into the evaluation of the Surry 1 and 2 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.
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 Surry 1 and 2 RPV circumferential
beltline welds. This change to Surry 1 and 2 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
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), the exemptions are authorized by law, will not present an
undue risk to the public health and safety, and are consistent with the
common defense and security. Also, special circumstances are present.
Therefore, the Commission hereby grants the Virginia Electric and Power
Company exemptions from the 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 Surry 1 and
2 RPV circumferential beltline welds with the following conditions:
(1) The licensee must utilize the data and methodology specified in
the NRC staff's safety evaluation (SE), dated August 4, 2005, which was
based on: (a) Information submitted by the B&WOG in TR BAW-2308,
Revision 1; (b) the August 19, 2003, response to an NRC staff Request
for Additional Information (ADAMS Accession Number ML032380449); and
(c) B&WOG letter dated March 25, 2005 (ADAMS Accession Number
ML051320232);
(2) When additional fracture toughness data relevant to the
evaluation of the Surry 1 and 2 RPV circumferential welds is acquired
as part of the ongoing plant RPV surveillance programs, the licensee
must re-evaluate the fracture toughness of the units' RPV
circumferential welds; and
(3) The exemptions are granted for the licensee to utilize the most
recent staff-approved version of BAW-2308 (currently BAW-2308, Revision
1). Future revisions of BAW-2308 could affect fracture toughness data
and analyses for Surry 1 and 2. Therefore, the licensee must review any
future staff-approved revisions of BAW-2308 and update the units'
fracture toughness assessments, based on the information in any staff-
approved revision of BAW-2308.
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 (72 FR 35264).
This exemption is effective upon issuance.
Dated at Rockville, Maryland, this 27th day of June 2007.
For the Nuclear Regulatory Commission.
Catherine Haney,
Director, Division of Operating Reactor Licensing, Office of Nuclear
Reactor Regulation.
[FR Doc. E7-12855 Filed 7-2-07; 8:45 am]
BILLING CODE 7590-01-P