ULNRC-04997, Revision to Request for Relief from ASME Section III Requirements Regarding Non-destructive Examination of Welds Performed Under Site Repair/Replacement Program
| ML041390519 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/07/2004 |
| From: | Keith Young AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-04997 | |
| Download: ML041390519 (11) | |
Text
AmerenUE Callaway Plant PO Box 620 Fulton, MO 65251 May 7, 2004 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 Ladies and Gentlemen:
ULNRC-04997 10 CFR 50.55a wiAmeren UF DOCKET NUMBER 50-483 UNION ELECTRIC COMPANY CALLAWAY PLANT REVISION TO REQUEST FOR RELIEF FROM ASME SECTION III REQUIREMENTS REGARDING NON-DESTRUCTIVE EXAMINATION OF WELDS PERFORMED UNDER SITE REPAIR/REPLACEMENT PROGRAM By letter dated October 17, 2002 (ULNRC-04760), as supplemented by letters dated October 30, 2002 (ULNRC-04768) and February 13, 2003 (ULNRC-04807),
Union Electric (AmerenUE) submitted, pursuant to 10 CFR 50.55a(a)(3)(i), a request for relief from requirements of the American Society of Mechanical Engineers (ASME) Code for the second 10-year inservice inspection interval at the Callaway plant. Specifically per the relief request, AmerenUE requested use of a proposed alternative to the non-destructive examination (NDE) requirements of Subarticle NC 5200 of Section III of the ASME Code (1974 Edition with Summer 1975 Addenda) for certain welds in Class 2 piping at the Callaway plant. The alternative approach would permit use of ultrasonic examination techniques in lieu of radiography for NDE of applicable welds.
The scope of the subject relief request evolved during the time between AmerenUE's initial submittal and the final submittal (of February 13, 2003).
Initially, AmerenUE's request was based on the potential outcome of activities associated with the Flow-Accelerated Corrosion (FAC) program at Callaway. It was noted in the October 17, 2002 submittal that much of the feedwater system was being monitored for pipe-wall thinning due to FAC and that inspections were expected to be performed in forthcoming refueling outages, i.e., RF-12 (completed at the end of 2002), RF-13 (which is currently underway), and RF-14 (which is the last refueling outage in the current 10-year ISI interval). It was anticipated that if the inspection results indicated the need to replace certain pipe sections, the requested relief would be used to facilitate NDE of the required welds. Because of the uncertainty in which particular pipe sections would need replacement, it was AmerenUE's intent to request a subsidiary ofAmeren Corporation
ULNRC-04997 May 7, 2004 Page 2 relief for all applicable Class 2 piping welds throughout the feedwater system, and not just to a specific list of welds or pipe sections. Discussions with the NRC indicated, however, that the scope of the relief request must be specific, and therefore a list of specific Class 2 feedwater pipe welds was included in the relief request provided in the October 17, 2002 submittal.
Subsequent to the October 17, 2002 submittal, the relief request was modified in response to questions / requests for information from the NRC. The revised relief request was provided to the NRC via AmerenUE's October 30, 2002 letter. Shortly after that, the anticipated FAC inspections were completed during RF-12. The results of those inspections confirmed no need for piping replacement, so the relief request was not immediately needed and thus not approved at that time.
Following RF-12, however, additional needs for the relief request were identified. These were identified from further planning and development of two significant modification activities, i.e., steam generator replacement (planned for RF-
- 14) and replacement of the actuators on the feedwater control valves in RF-13. For the former, specifically affected pipe sections (and the necessary welds for that replacement) were identified for the feedwater and main steam systems. For the latter, replacement of the feedwater control valve actuators themselves would not be require valve replacement, but it was recognized that one of the valves (AEFV0040) had been previously seal welded and would thus have to be removed and replaced.
The welds required for this valve replacement were thus identified. As a result of these activities, the scope of the subject relief request was expanded to include the additional welds in the feedwater and main steam systems, and the revised relief request was submitted to the NRC via AmerenUE's February 13, 2003 letter.
AmerenUE's request was subsequently approved by the NRC. Accordingly, Code relief to permit ultrasonic examination of pipe butt-welded joints and circumferential pipe welds, in lieu of Code-required radiography for the specific scope of feedwater and main steam pipe welds, was granted by NRC letter dated July 1, 2003.
With regard to the intended application of the relief request, the noted feedwater system modifications for replacement of the control valve actuators, including replacement of the AEFV0040 valve, are presently underway for the current refueling outage. During this work, however, it was determined that one of the new valve actuators could not be properly matched to its designated control valve (AEFV0042). It has been determined that this valve must be replaced with a new valve to which the actuator can be matched. Since it was not anticipated that this valve would need to be replaced, the welds required for installing the new valve are not included in the approved relief request. The welds required for this valve replacement are of the same type identified in the relief request and are for the same or similar application in the same system. The relief request should thus be
ULNRC-04997 May 7, 2004 Page 3 applicable to these welds, as the desire to do ultrasonic examination for the NDE of these welds in lieu of radiography still applies.
Based on the above, AmerenUE recognizes the need to revise the relief request to include the additional feedwater welds in its scope and to seek NRC approval of the revised relief request. Accordingly, the revised relief request is attached and submitted via this letter. Revision bars have been applied to indicate the changes made to the relief request (relative to what was previously approved).
As noted above, replacement of the AEFV0042 feedwater valve is currently underway in the current outage. Therefore, AmerenUE respectfully requests NRC approval of the revised relief request as soon as possible. It should be noted that, with regard to plant restart from the current outage, entry into plant heat-up conditions is currently projected to occur during the weekend of May 22. NRC approval is therefore requested on or by Friday, May 21, in anticipation of plant heat-up.
Please contact me at 573-676-8659 or Dave Shafer at 314-554-3104 for any questions you may regarding the revised relief request.
Sincerely, Keith D. Young Manager - Regulatory Affairs TBE/jdg Attachment
ULNRC-04997 May 7, 2004 Page 4 cc:
U.S. Nuclear Regulatory Commission (Original and 1 copy)
Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 Mr. Bruce S. Mallett Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Missouri Public Service Commission Governor Office Building 200 Madison Street PO Box 360 Jefferson City, MO 65102-0360
ULNRC-04997 Attachmcnt Page I of 6 Request to Use Alternative Ultrasonic Examination Method in Lieu of the Radiography Required by ASME Section III, Subarticle NC-5200
Background:
The 1989 Edition with no Addenda of ASME Section Xl currently governs repair/replacement activities at the Callaway Nuclear Plant. Callaway Plant is currently in the second 10-year inservice inspection interval which began on August 1, 1995. ASME Class 2 welds installed under the Callaway Repair/Replacement Program are nondestructively examined in accordance with the 1974 Edition with Summer 1975 Addenda of ASME Section IlIl. Alternatively, when pressure testing is performed in accordance with Code Case N-416-1, the welds are nondestructively examined in accordance with the 1992 Edition with no Addenda of ASME Section IlIl. Pursuant to the provisions of IOCFR 50.55a(a)(3)(i), Callaway Plant requests permission to use an alternative ultrasonic examination method in accordance with the justification, requirements, and provisions detailed below in lieu of the radiography required by ASME Section IlIl, NC-5200.
Components for Which Alternative Ultrasonic Examination is Requested:
Alternative ultrasonic examination is requested for Class 2 feedwater pipe welds listed in Table 1 and Class 2 main steam pipe welds listed in Table 2. These tables list a piping description, weld identification number, nominal pipe size, pipe schedule, and base material for each weld.
Justification for Alternative Ultrasonic Examination in Lieu of Radiography:
The proposed alternative ultrasonic examination will ensure an adequate level of safety and quality and will provide adequate verification that the Class 2 welds are free of significant flaws that could affect structural integrity. The examination will cover 100% of the weld volume and include base material for a distance of 1/2 the nominal through-wall weld thickness on each side of the weld. A demonstration of the ultrasonic examination system capability to detect both subsurface and surface workmanship type flaws (i.e., slag, porosity, lack of fusion, and incomplete penetration) will be performed on a qualification block. All flaws and indications will be evaluated in accordance with the standard acceptance criteria of NC-5330. In addition, an automated scan and data acquisition system will be used to improve examination repeatability and provide permanent storage of the raw data. Finally, the proposed alternative ultrasonic examination will be limited to base material and weld material that is conducive to ultrasonic examination.
Ultrasonic and radiographic examination methods are complimentary and are not directly comparable or equivalent. Depending on flaw type (i.e., volumetric or planar) and orientation, ultrasonic examination may be superior to radiography or vice versa. Radiography is most effective in detection of volumetric type flaws (i.e., slag and porosity) and detection of planar type flaws (i.e., lack of fusion and cracks) that are oriented in a plane parallel to the x-ray beam.
However, radiography is limited in detection of planar flaws not oriented parallel to the beam. In contrast, ultrasonic examination is very effective in detection of planar type flaws that are not oriented in a plane parallel to the sound beam and less effective in detecting flaws in a plane parallel to the sound beam. Finally, ultrasonic examination is capable of detecting volumetric type flaws such as slag or porosity but is limited, compared to radiography, in ability to characterize volumetric flaws.
The proposed alternative ultrasonic examination requirements and provisions address the known limitations of the ultrasonic method to ensure both planar and volumetric flaws in all orientations are detected and properly evaluated. First, examination using two angle beams (i.e., 45 and 60 degree nominally) or a procedure qualified on 100% of the weld volume in accordance with the performance demonstration methodology of Section Xl, Appendix ViIl is required. Second, examination scans in two directions perpendicular to the weld axis and two directions parallel to the weld axis or examination scans as qualified on 100% of the weld volume in accordance with
ULNRC-04997 Attachment Pagc 2 of 6 the performance demonstration methodology of Section Xl, Appendix Vil are required. Third, to ensure laminar type flaws are detected, a supplemental examination using straight beam is also required. Finally, if an indication, such as slag or porosity, is not characterized as volumetric, the indication will be characterized as a planar type flaw and evaluated in accordance with the acceptance criteria of NC-5330. The acceptance criteria of NC-5330 specify acceptable lengths of indications only and do not differentiate between planar and volumetric type flaws. Most importantly, planar type flaws such as cracks, incomplete penetration, and lack of fusion, which are rejectable by NC-5330 for any size, are more readily and properly characterized by ultrasonic examination.
In addition to the effectiveness of the proposed alternative, use of ultrasonic examination in lieu of radiography will provide a significant reduction in personnel radiation exposure during refueling outage maintenance work. Also, outage duration and costs will be reduced by allowing parallel path work to progress uninterrupted during examination of welds. Finally, the personnel safety risk of inadvertent or accidental exposure and also the normal anticipated exposure associated with transporting, positioning and exposing a source for radiography is eliminated.
Proposed Alternative Ultrasonic Examination Requirements and Provisions:
For ASME Class 2 welds installed under the Callaway Repair/Replacement Program where ultrasonic examination will be performed in lieu of radiography the following requirements shall apply:
(1) The nominal weld thickness shall be 1/2 inch or greater.
(2) The ultrasonic examination shall not be applied to welds that include austenitic cast product forms or austenitic corrosion-resistant-clad piping butt welds.
(3) The ultrasonic examination area shall include 100% of the volume of the entire weld plus 0.5T on each side of the weld, where T is the nominal thickness of the weld.
The ultrasonic examination area shall be accessible for angle beam examination in four directions, two directions perpendicular to the weld axis and two directions parallel to the weld axis. Where perpendicular scanning is limited on one side of the weld, a technique using the second leg of the V-path may be credited as access for the second perpendicular examination direction provided that the detection capability of that technique is included in the procedure demonstration described in (5) and (6) below.
(4) The ultrasonic examination shall be in accordance with (a) or (b) below:
(a) Examination shall be performed in accordance with Section V, Article 5 up to and including the 2001 Addenda. Two angle beams having nominal angles of 45 and 60 degrees should generally be used; however, other pairs of angle beams may be used provided the measured difference between the angles is at least 10 degrees. Examination scans shall be in four directions; two beam path directions perpendicular to the weld axis and two beam path directions parallel to the weld axis. Where the examination scan perpendicular to the weld is limited on one side, the second leg of the V-path may be used to achieve the two beam path directions. A supplemental straight beam shall also be used.
(b) Examination shall be performed by a procedure qualified in accordance with the performance demonstration methodology of Section Xl, Appendix Vill provided the entire volume of the weld examination is included in the demonstration.
Examination scans shall be in four directions; two beam path directions perpendicular to the weld axis and two beam path directions parallel to the weld axis. A supplemental straight beam shall also be used.
(5) A written procedure shall be followed. The procedure shall be demonstrated to perform acceptably on a qualification block or specimen that includes a weld with both surface and subsurface flaws as described in (7) below.
ULNRC-04997 Attachmcnt Pagc 3 of 6 (6) The qualification block material shall conform to the requirements applicable to the calibration block and in addition meet the following requirements:
(a) The material from which blocks are fabricated shall be one of the following: a nozzle dropout from the component; a component prolongation; or material of the same material specification, product form, and heat treatment condition as one of the materials joined. For piping, if material of the same product form and specification is not available, material of similar chemical analysis', tensile properties, and metallurgical structure2 may be used.
(b) Where two or more base material thicknesses are involved, the calibration block thickness shall be of a size sufficient to contain the entire examination path.
(c) Qualification block configuration shall contain a weld representative of the joint to be ultrasonically examined, including, for austenitic materials, the same welding process.
(7) The qualification block shall include flaws in accordance with (a) or (b) below:
(a) At least two planar flaws shall be included in the qualification block weld, one surface and one subsurface oriented parallel to the fusion line. The flaws shall be no larger in the through-wall direction than the diameter of the applicable side-drilled hole in the calibration block shown in Figure T-542.2.1 of Section V, Article 5, and no longer than the shortest unacceptable elongated discontinuity length listed in NC-5330 for the thickness of the weld that will be examined.
(b) Where a Section Xl, Appendix VilI, performance demonstration methodology is used, supplemental qualification to a previously approved procedure may be demonstrated through the use of a blind test with appropriate specimens that contain a minimum of three different construction-type and fabrication-type flaws distributed throughout the thickness of the specimen(s).
(8) A documented examination plan shall be provided showing the transducer placement, movement and component coverage that provides a standardized and repeatable methodology for weld acceptance. The examination plan shall also include the ultrasonic beam angle used, beam directions with respect to weld centerline, and volume examined for each weld.
(9) The ultrasonic examination shall be performed using a device with an automated computer data acquisition system.
(10) Data shall be recorded in unprocessed form. A complete data set with no gating, filtering, or thresholding for response from the examination volume in paragraph (3) above shall be included in the data record.
(11) Personnel who acquire and analyze ultrasonic data shall be qualified and trained using the same type of equipment as in (9) above, and demonstrate their capability to detect and characterize the flaws using the procedure as described in (5) above.
(12) The evaluation and acceptance criteria shall be in accordance with Section III NC-5330.
(13) Flaws exceeding the applicable acceptance criteria referenced in (12) above shall be repaired, and the weld subsequently reexamined using the same ultrasonic examination procedure that detected the flaw.
(14) Review and acceptance of the ultrasonic examination procedure by the Authorized Nuclear Inservice Inspector is required.
(15) All other related requirements of the Callaway Repair/Replacement Program shall be met.
1 Chemical composition is within the same ranges as required in the original material specification.
2 Same phase and grain shape as produced by the thermal process for the original specification.
ULNRC-04997 Attachmcnt Pagc 4 of 6 (16) Use of ultrasonic examination in lieu of radiography shall be documented in accordance with the Callaway Repair/Replacement Program on a Form NIS-2A and/or Section Xl Repair/Replacement Plan, as applicable.
ULNRC-04997 Attachmcnt Pagc 5 of 6 Table 1: Feedwater Pipe Welds Description Weld ID No. (1)
NPS Sch.
Mat.
2-AE-04-F014 (2) 14 80 CS 5-Dia. bend & expander upstream of A S/G inlet 2-AE-04-SO10-A 14 80 CS 2-AE-04-SO10-C 16 80 CS 2-AE-04-F015 16 80 CS 2-AE-04-F030 (2) 14 80 CS 2-AE-04-FW8 14 80 CS 5-Dia. bend & expander upstream of B SJG inlet 2-AE-04-FW7 14 80 CS 2-AE-04-S021-C 16 80 CS 2-AE-04-F035 16 80 CS 2-AE-05-F030 (2) 14 80 CS 5-Dia. bend & expander upstream of C S/G inlet 2-AE S021-A 14 80 Cs 2-AE-05-S021 -C 16 80 CS 2-AE-05-F036 16 80 CS 2-AE-05-F015 (2) 14 80 CS 5-Dia. bend & expander upstream of D S/G inlet 2-AE-05-S022-A 14 80 CS 2-AE-05-S022-C 16 80 Cs 2-AE-05-F035 16 80 CS Feedwater isolation valve AEFV0040 2-AE-04-F020 14 120 CS 2-AE-04-F019 14 120 CS 2-AE-04-S017-A 14 80 CS Elbow & pipe upstream of valve AEV0120 (B loop) 2-AE-04-F027 14 80 CS 2-AE-04-F067 14 80 CS 2-AE-04-F070 14 80 CS Elbow & pipe downstream of valve AEV0120 (B loop) 2-AE-04-SO1 9-A 14 80 CS 2-AE-04-FWI0 14 80 CS Elbow downstream of valve AEV0123 (C loop) 2-AE-05-F029 14 80 CS 2-AE-05-S020-A 14 80 CS 2-AE-05-F012 14 80 CS Elbow & pipe upstream of valve AEV0122 (D loop) 2-AE-05-S008-A 14 80 CS 2-AE-05-F073 14 80 CS 2-AE-05-F004 14 120 CS Feedwater isolation valve AEFV0042 (D loop) 2-AE-05-F005 14 120 CS 2-AE-05-F006 (2) 14 120 CS Notes:
(1) Listed Weld ID Numbers are those currently identified in the Callaway ISI Program Plan.
(2) New weld will be at this weld location or several inches upstream.
ULNRC-04997 Attachmcnt Pagc 6 of 6 Table 2: Main Steam Pipe Welds Description Weld ID No. (1)
NPS Sch.(2)
Mat.
2-AB-01-FOOl 32 1.068" CS Pipe, reducer & elbow downstream of A SIG outlet 2-AB-01-S001-A 32 1.068" CS 2-AB-01-S001-D 28 0.934" CS new pipe weld (3) 28 0.934" CS 2-AB-01-F020 32 1.068" CS Pipe, reducer & elbow downstream of B SIG outlet 2-AB-01-SO13-A 32 1.068" CS 2-AB-01-S013-D 28 0.934" CS new pipe weld (3) 28 0.934" CS 2-AB-01 -F044 32 1.068" CS Pipe, reducer & elbow downstream of C SIG outlet 2-AB-01-S027-A 32 1.068" CS 2-AB-01-S027-D 28 0.934" CS new pipe weld (3) 28 0.934" CS 2-AB-01-F068 32 1.068" CS Pipe, reducer & elbow downstream of D S/G outlet 2-AB-01-S041-A 32 1.068" CS 2-AB-01-S041-D 28 0.934" CS new pipe weld (3) 28 0.934" CS Notes:
(1) Listed Weld ID Numbers are those currently identified in the Callaway ISI Program Plan.
(2) Minimum wall thickness is listed in pipe schedule column.
(3) New weld to be in pipe section downstream of 1st elbow from SIG outlet.
CALLAWAY OUTGOING CORRESPONDENCE REVIEW Submittal Due Date Responsible Manae Kelth Young Ed.
58659 0 Required 0 Requested O /A RAContact Tom Eiwood Exi.
44593
~~~~an.A Correspondence No.:
ULNRC04997 Revision of Request for Reflef from ASME Section XI Requirements to Permit Ultasonic Examination in Lieu of Radiography br Specified Welds in Feedwater and Main Steam Piping
Subject:
Screening:
nItial/Date Initia Posting required per 10 CFR 19.11 (Other)?
0 Yes D
0 Not1PL Processed hi aorce with APAIZ-00521, Attachment 9 Correspondence is an official report that 0 Yes I_
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requires additional reporting I distribution?
,oA-In.00ewi 0_AP No Correspondence contains Commitments?
D Yes No_
See Commitment Summary in Conespondence Processed I acordac with APA-ZZW0540 Correspondence adds a new or modified design basis, safety analysis or facility operation as o Yes Not-ME described by the FSAR or similarly impacts other e
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NoSf LicensingDocument ChangeNotice?
Technical Review Date Review Due Date to Suppl Signature Completed Regulatory Affairs: Tom Elwood B y ii.
51 /104 Responsible Department:
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Engineering ISI Group: S. L. McCracken R uP ory Affairs review hi the above block Indicates format mnd content Is consistent with regulatory requirermet or requests. Depabnental review indicates that the correspondence has been coordnated with 1he qpro ate organzations and Is technically corred; as well as indicat ngconarce with cornmntments and due dates.
Senior Management Review i
Date E ApprovalRequiredunderOath!AffirmationlDeclaration l
Signature Completed O
Senior Vice President and Chief Nuclear Officer
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Vice President Nuclear 0
Plant Manager 5
Manager - Regulatory Affairs IUZfiZZIZI 0
Manager -Nuclear Engineering I_/___/
O Manager - Quality Assurance O
Manager - Operations Support Signatures In the above block Indicate that content is consistent with company expectations on approach and responsiveness.
Remarks I Comments: This submittal transmits a revision of an ASME Section Xl Relief Request that was previously approved for Callaway. NRC approval of the revised Relief Request Is thus being requested. The Relief Request (as approved) permits ultrasonic examination methods to be used In lieu of ASME Code-required radiography for the nondestructive examination (NDE) of welds specifically identified In the relief request Ile., for specific welds In the feedwater and main steam systems). While completing the modification for replacing the actuators on the feedwater control valves during the current outage (RF.13) an unexpected problem was encountered that requires removal and replacement of the AEFV0042 valve. Since replacement of this valve was not anticipated, the welds required for Installation of the replacement valve are not Included In the subject Relief Request. The desire to perform ultrasonic examination In lieu of radiography for these welds still applies, so the RelIef Request must be revised to Include these welds In Its scope If the alternative NDE approach is to be permitted. This letter (ULNRC404997) transmits the revised Relief Request to the NRC and requests their approval of the revision prior to heat-up from the current outage.
CA2639 12108/03