1CAN031403, Request for Exemption from Certain 10 CFR 50.61 and 10 CFR 50, Appendix G Requirements
| ML14083A640 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/20/2014 |
| From: | Pyle S Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 1CAN031403 | |
| Download: ML14083A640 (9) | |
Text
Entergy Operations, Inc.
1448 S.R. 333 Russellville, AR 72802 Tel 479-858-4704 Stephenie L. Pyle Manager, Regulatory Assurance Arkansas Nuclear One 1CAN031403 March 20, 2014 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Request for Exemption from Certain 10 CFR 50.61 and 10 CFR 50, Appendix G Requirements Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51
Dear Sir or Madam:
Entergy Operations, Inc. (Entergy) is currently developing new 54 Effective Full Power Years (EFPY) pressure - temperature limits for Arkansas Nuclear One, Unit 1 (ANO-1). 54 EFPY is the anticipated end of the current renewed operating license period for ANO-1. These proposed limits are required to be submitted for review and approval in the future. To support the development of these limits, Entergy is requesting an exemption from certain requirements of 10 CFR 50.61, Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events and 10 CFR 50, Appendix G, Fracture Toughness Requirements.
The requested exemption would allow use of an alternate method, described in AREVA Inc.
Topical Report BAW-2308, Revision 1-A and 2-A, Initial RTNDT of Linde 80 Weld Materials, for determining the initial, unirradiated material reference temperatures of Linde 80 weld materials present in the ANO-1 reactor pressure vessel beltline.
The topical report was developed to provide an alternate method for determining the initial nil ductility reference temperature (RTNDT) for Linde 80 welds in Babcock and Wilcox fabricated reactor vessels. The alternative methodology was based on brittle-to-ductile transition range fracture toughness test data of the weld materials in accordance with American Society of Testing Materials Standard E1921 and using American Society of Mechanical Engineers (ASME) Code Case N-629. This methodology would be used in lieu of the RTNDT parameter specified in ASME Section III Paragraph NB-2331. The use of ASME Section III Paragraph NB-2331 is specified in 10 CFR 50, Appendix G(II)(D)(i), and its use is also described in Regulatory Guide 1.99.
1CAN031403 Page 2 of 3 The Safety Evaluation (SE) for Revision 1-A of the topical report contained six conditions.
Licensees have to satisfy four of these conditions in order to use the alternate methodology.
The first three conditions describe performance requirements for use of the methodology.
These conditions have been satisfied. The fourth condition requires the submittal of an exemption request from the requirements of 10 CFR 50.61 and 10 CFR 50, Appendix G in order to use the methodology. The exemption request is attached.
The topical report was revised to incorporate additional information from the Pressurized Water Reactor Owners Group to satisfy the remaining two conditions contained in the NRC SE for Revision 1-A. The SE for Revision 2-A required licensees to follow the four conditions contained in the SE for Revision 1-A. The SE for BAW-2308, Revision 2-A also stated that the initial RTNDT values for certain materials contained in the Revision 1-A version are more conservative.
A similar exemption request was approved by the NRC in an SE, dated December 13, 2013, for Three Mile Island Unit 1 (ML13325A023).
This report includes no new regulatory commitments.
If you have any questions or require additional information, please contact me.
Sincerely, Original signed by Stephenie L. Pyle SLP/rwc
Attachment:
Request for Exemption from 10 CFR 50.61 and 10 CFR 50, Appendix G Requirements
1CAN031403 Page 3 of 3 cc: Mr. Marc L. Dapas Regional Administrator U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Arkansas Nuclear One P. O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Peter Bamford MS O-8B3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 U. S. Nuclear Regulatory Commission Attn: Mr. Michael Orenak MS O-8G9A One White Flint North 11555 Rockville Pike Rockville, MD 20852
Attachment to 1CAN031403 Request for Exemption from 10 CFR 50.61 and 10 CFR 50, Appendix G Requirements
Attachment to 1CAN031403 Page 1 of 5 Request for Exemption from 10 CFR 50.61 and 10 CFR 50, Appendix G Requirements INTRODUCTION In accordance with the provisions of 10 CFR 50.60(b) and 10 CFR 50.12, Entergy Operations, Inc. (Entergy) requests an exemption from certain requirements of 10 CFR 50.61, Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events, and 10 CFR 50, Appendix G, Fracture Toughness Requirements. The exemption would allow use of alternate initial RTNDT (reference nil ductility temperature), as described in AREVA Inc.
(AREVA) Topical Report (TR) BAW-2308, Revisions 1-A and 2-A, for determining the adjusted RTNDT of the Linde 80 weld material present in the Arkansas Nuclear One, Unit 1 (ANO-1) reactor pressure vessel (RPV) beltline.
BACKGROUND 10 CFR 50.61(a)(5) and 10 CFR 50, Appendix G, (II)(D)(i), require that the pre-service or unirradiated condition RTNDT be evaluated to the procedures in the American Society of Mechanical Engineers (ASME) Code,Section III, Paragraph NB-2331, from Charpy V-notch impact tests and drop-weight tests. In addition, 10 CFR 50.61 permits other methods for use in determining the initial material properties provided such methods are approved by the Director, Office of Nuclear Reactor Regulation.
AREVAs BAW-2308, Revisions 1-A and 2-A provides NRC-approved alternate initial RTNDT and associated i values of the Linde 80 materials present in the beltline of the RPV at ANO-1.
BAW-2308, Revision 2-A is a supplement to Revision 1-A and incorporated additional test data and a re-evaluation of the reference temperature, T0, determination, as required by the NRC in the Safety Evaluation (SE) for Revision 1-A of BAW-2308.
The Conditions and Limitations, Items (1) through (4), contained in the SE for Revision 1-A of the topical report must be satisfied in order for licensees to reference the topical report in specific licensing applications.
Condition and Limitation (1) pertains to NRC-accepted values of initial (unirradiated) reference temperature, IRTT0 and the corresponding uncertainty term, i, for Linde 80 weld materials based on the Master Curve methodology using direct testing of fracture toughness in accordance with American Society of Testing Materials (ASTM) Standard Test Method E1921.
Condition and Limitation (2) requires a minimum chemistry factor of 167.0°F be applied when the methodology of Regulatory Guide (RG) 1.99, Revision 2 and 10 CFR 50.61 is used to assess the shift in nil-ductility transition temperature due to irradiation.
Condition and Limitation (3) requires that a value of = 28.0°F be used to determine the margin term, as defined in BAW-2308, Revision 2-A and Regulatory Guide 1.99, Revision 2.
Attachment to 1CAN031403 Page 2 of 5 Condition and Limitation (4) as stated in the NRC SE for BAW-2308, Revision 1-A requires:
Any licensee who wants to utilize the methodology of TR BAW-2308, Revision 1 as outlined in items (1) through (3) above, must request an exemption, per 10 CFR 50.12, from the requirements of Appendix G to 10 CFR 50 and 10 CFR 50.61 to do so. As part of a licensees exemption request, the NRC staff expects that the licensee will also submit information which demonstrates what values the licensee proposes to use for RTNDT and the margin term for each Linde 80 weld in its RPV through the end of its facilitys current operating license.
Table 1 contains the information requested above.
Entergy is planning to revise the ANO-1 pressure - temperature limits for operation up to 54 Effective Full Power Years (EFPYs). Entergy desires to use the BAW-2308 initial RTNDT values in the new analyses. Therefore, exemption from certain requirements of 10 CFR 50.61 and 10 CFR 50, Appendix G is required.
PROPOSED EXEMPTION The exemption requested by Entergy addresses portions of the following regulations:
(1) Appendix G to 10 CFR Part 50 which sets 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; and (2) 10 CFR 50.61, which sets forth fracture toughness requirements for protection against pressurized thermal shock (PTS).
The exemption from Appendix G to 10 CFR 50 is to replace the required use of the existing Charpy V-notch and drop-weight-based methodology with the use of an alternate methodology that incorporates the use of fracture toughness test data for evaluating the integrity of the Linde 80 weld materials present in the ANO-1 RPV beltline region. The alternate methodology employs direct fracture toughness testing per the Mater Curve methodology based on use of ASTM Standard Method E1921 (1997 and 2002 Editions) and ASME Code Case N-629. The exemption is required since Appendix G to 10 CFR 50 requires that for the pre-service or unirradiated condition, RTNDT be evaluated by Charpy V-notch impact tests and drop-weight tests according to the procedures in the ASME Code,Section III, Paragraph NB-2331.
The exemption from 10 CFR 50.61 is to use an alternate methodology to allow the use of direct fracture toughness test data for evaluating the integrity of the Linde 80 weld materials present in the ANO-1 RPV beltline, based on the use of ASTM E1921 (1997 and 2002 Editions) and ASME Code Case N-629. The exemption is required because the methodology for evaluating RPV material fracture toughness in 10 CFR 50.61 requires that the pre-service or unirradiated condition be evaluated using Charpy V-notch impact tests and drop-weight tests according to the procedures in the ASME Code,Section III, Paragraph NB-2331.
Attachment to 1CAN031403 Page 3 of 5 Additionally, the NRCs SE for TR BAW-2308, Revision 1-A, concludes that an exemption is required to address issues related to 10 CFR 50.61 in as much as the methodology presented in Topical Report BAW-2308, Revision 1-A, as modified and approved by the NRC staff, represents a significant change to the methodology specified in 10 CFR 50.61 for determining the PTS reference temperature (RTPTS) value for Linde 80 weld material. The changes in the methodology described in BAW-2308, Revisions 1-A and 2-A, with respect to the methodology per 10 CFR 50.61, include the requirements for use of a minimum chemistry factor of 167.0°F and a value of = 28.0°F for Linde 80 weld materials.
10 CFR 50.12 states that the Commission may grant an exemption from the requirements contained in 10 CFR 50 provided that: (1) the exemption is authorized by law; (2) the exemption will not result in an undue risk to public health and safety; (3) the exemption is consistent with the common defense and security; and (4) special circumstances, as defined in 10 CFR 50.12(a)(2) are present. The requested exemption to allow the use to TR BAW-2308, Revisions 1-A and 2-A, as the basis for the RPV beltline Linde 80 weld material initial properties at ANO-1 satisfy these requirements as described below.
(1) The requested exemption is authorized by law No law exists which precludes the activities covered by this exemption request.
10 CFR 50.60(b) allows the use of alternatives to 10 CFR 50, Appendix G when an exemption is granted by the Commission under 10 CFR 50.12 In addition, 10 CFR 50.61 permits other methods for use in determining the initial material properties provided such methods are approved by the Director, Office of Nuclear Reactor Regulation.
(2) The requested exemption will not present an undue risk to the public health and safety The proposed material initial properties basis described in TR BAW-2308, Revisions 1-A and 2-A represent an NRC-approved methodology for establishing weld wire specific and generic IRTT0 values for Linde 80 welds. TR BAW-2308, Revisions 1-A and 2-A, includes appropriate conservatisms to ensure that use of the proposed initial material properties basis does not increase the probability of occurrence or the consequences of an accident at ANO-1, and does not create the possibility of a new or different type of accident that could pose a risk to public health and safety.
The use of this proposed approach ensures that the intent of the requirements specified in 10 CFR 50.61 and 10 CFR 50, Appendix G are satisfied.
The requested exemption is consistent with the NRC staff requirements specified in the SE for the approved TR BAW-2308, Revisions 1-A and 2-A; consequently, the exemption does not present and undue risk to the public health and safety.
Attachment to 1CAN031403 Page 4 of 5 (3) The requested exemption will not endanger the common defense and security The requested exemption is specifically concerned with RPV material properties and is consistent with NRC staff requirements specified in the SE for approved TR BAW-2308, Revisions 1-A and 2-A. Consequently, the requested exemption does not endanger the common defense and security.
(4) Special circumstances are present which necessitate the request for an exemption to the regulations of 10 CFR 50.61 and 10 CFR 50, Appendix G Pursuant to 10 CFR 50.12(a)(2), the NRC will not consider granting an exemption to the regulations unless special circumstances are present.
The requested exemption meets the special circumstances of 10 CFR 50.12(a)(2)(ii) since application of the methodology in BAW-2308, Revisions 1-A and 2-A, in this particular circumstance serves the underlying purpose of the regulations.
The underlying purpose of 10 CFR 50.61 and 10 CFR 50, Appendix G is to protect the integrity of the reactor coolant pressure boundary by ensuring that each reactor vessel material has adequate fracture toughness. Application of paragraph NB-2331 of ASME Code Section III in the determination of the initial material properties was conservatively developed based on the level of knowledge existing in the early 1970s concerning RPV materials and the estimated effects of operation. Since the early 1970s, the level of knowledge concerning these topics has greatly expanded. This increased knowledge level permits relaxation of the ASME Code,Section III, NB-2331 requirements via application of TR BAW-2308, Revisions 1-A and 2-A while maintaining the underlying purpose of the ASME Code and NRC regulations to ensure an acceptable margin of safety is maintained.
The proposed change in RPV material initial properties continues to satisfy the intent of 10 CFR 50.61 and 10 CFR 50, Appendix G, thus justifying the exemption request. Issuance of an exemption from the criteria of these regulations to permit the use of BAW-2308, Revisions 1-A and 2-A for ANO-1 does not compromise the safe operation of the reactor and ensures that RPV integrity is maintained.
A similar exemption request was approved by the NRC in a SE, dated December 13, 2013, for Three Mile Island Unit 1 (ML13325A023).
Attachment to 1CAN031403 Page 5 of 5 TABLE 1 1/4 T and 3/4 T Adjusted Reference Temperature Values for Beltline Welds Through 54 EFPY (Using BAW-2308, Rev. 2-A Methodology)
Material ID / RTNDT (°F) Margin (°F) ART (°F)
Initial RTNDT Beltline Welds Acceptance
(°F)
No. 1/4T 3/4T 1/4T 3/4T 1/4T 3/4T LNBF to US Circ. Weld WF-182-1 -84.2 161.1 112.7 59.2 59.2 136.1 87.7 US 1 to US 2 Long. Welds WF-18 -48.6 145.5 100.7 66.6 66.6 163.5 118.6 US to LS Circ. Weld WF-112 -98.0 168.5 118.5 60.6 60.6 131.1 81.1 LS 1 to LS 2 Long. Welds WF-18 -48.6 148.8 103.6 66.6 66.6 166.8 121.6 LNBF = Lower Nozzle Belt Forging US = Upper Shell LS = Lower Shell Circ. = Circumferential Long. = Longitudinal