ULNRC-04768, Amerenue - Revision to Request for Relief from ASME Section III Requirements Regarding Non-Destructive Examination of Welds Performed Under Site Repair/Replacement Program for Callaway, Unit 1
| ML023100362 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 10/30/2002 |
| From: | Blosser J AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MB6534, ULNRC-04768 | |
| Download: ML023100362 (11) | |
Text
AmerenUE One Ameren Plaza 1901 Chouteau Avenue PO Box 66149 St. Louis, MO 63166-6149 314 621.3222 October 30, 2002 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 Ladies and Gentlemen: LTLNRC-04768 DOCKET NUMBER 50-483 UNION ELECTRIC COMPANY wAmeren CALLAWAY PLANT UNIT 1 REVISION TO REQUEST FOR RELIEF FROM 11E ASME SECTION III REQUIREMENTS REGARDING NON-DESTRUCTIVE EXAMINATION OFWELDS PERFORMED UNDER SITE REPAIR/REPLACEMENT PROGRAM (TAC# MB6534)
By letter dated October 17, 2002 (Letter ULNRC-04760) Union Electric (AmerenUE) submitted an American Society of Mechanical Engineers (ASME) Code relief request pursuant to 10CFR50.55a(a)(3)(i) for use of a proposed alternative to the non-destructive examination (NDE) requirements of Subarticle NC 5200 of Section III of the ASME Code. That request, which is now under review by the NRC staff, is being made for the NDE of welds that may be required if certain pipe sections of the main feedwater system at Callaway are replaced during the current refueling outage at Callaway, which began October 23. As noted in the October 17 letter, the subject Class 2 pipe sections may require replacement based on the results of pipe wall inspections to be performed in response to the identification of pipe wall thinning in certain sections of the feedwater system during the last refueling outage at Callaway (RF- 11). For the welds that may be required, and for the reasons stated in our October 17 letter, AmerenUE prefers to perform ultrasonic examination of the welds in lieu of radiography required by Subarticle NC 5200. Details of the ultrasonic examination method to be used, and justification for this alternative method, were provided in the relief request document that was attached to the October 17 letter.
Subsequent to submittal of the subject relief request, AmerenUJE received a request for additional information (RAI) from the NRC staff via electronic mail on October 23, 2002. The request is in the form of two comments that request clarification of information provided in the relief request document. One comment concerns a technical aspect of the ultrasonic examination procedure with regard to the directions/angles of the applied beam paths; the other comment concerns conformance to the qualification requirements of ASME Section XI, Appendix VIII, including performance demonstration, for qualification of the procedure and personnel involved.
a subsidiary ofAmeren Corporation
i TJLNRC-04768 October 30, 2002 Page 2 AmerenUE was asked to provide its response to the two comments in writing to the NRC staff, and therefore, the two comments and AmerenUE's responses to the comments are hereby provided in Attachment 1 to this letter. Also, because the relief request document itself was revised in response to the NRC comments, the revised document is provided as Attachment 2. Revision bars indicate where the changes were made to the document.
AmerenUE appreciates the NRC staff s prompt review being given to the subject relief request. For any further questions or requests for additional information that you may have, please contact David Shafer at 314-554-3104, or Thomas Elwood at 314-554-4593.
Very truly yours, John D. Blosser Manager - Regulatory Affairs TBE/jdg Attachments
ULNRC-04768 October 30, 2002 Page 3 cc: U. S. Nuclear Regulatory Commission (Original and 1 copy)
Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 Mr. Ellis W. Merschoff 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 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102
Attachment 1 ULNRC-04768 Page 1 of2 Response to NRC Request for Additional Information NRC Ouestions With regard to the information provided in AmerenUE's relief request (i.e., the attachment to Letter ULTNRC-04760 dated October 17, 2002):
- 1. There is a disconnect between what is stated in the Justificationfor an Alternative section andwhat is stated in the ProposedAlternative section.
The Justificationstates that scans in two directionsperpendicularto the weld axis and two directionsparallelto the weld axis are required(for Section V andAppendix VIII examinations). This is inline with priorphone conversationswith Callavay.
Item (3) in the ProposedAlternative only states that accesswill be providedfor these scans.
In Item (4) of the ProposedAlternative,it shouldstate that the examinationswill be performed infour directionswith the full V optionfor scanningperpendiculartoferritic welds. [See Item (3).]
- 2. Since Callaway intends on using Section X, Appendix VIII, Callaway shouldstate that. Is this a true statement?: "The UTpersonnelandprocedurewill be qualified using the methodology of Appendix 1III to ASME Section XI administeredby the Performance DemonstrationInitiative."
Callaway Plant Response to RAI Callaway Plant will use a procedure and UT personnel that are qualified in accordance with Section XI, Appendix VIII. As specified by Item (7)(b), this Appendix VIII qualification was supplemented by an additional performance demonstration at the EPRI NDE Center on a qualification block with implanted flaws that satisfy the requirements of Item (6) and (7) of the Proposed Alternative. This supplemental demonstration verified capability of both the procedure and personnel to detect construction-type and fabrication type flaws distributed throughout the thickness of the weld volume. The demonstration was blind and was administered by EPRI NDE Center personnel following EPRI protocol.
However, this supplemental demonstration was not officially administered under the auspices of the Performance Demonstration Initiative (PDI) because the demonstration was not within the administrative scope of the PDI.
V Attachment 1 ULNRC-04768 Page 2 of 2 To improve understanding of the intent of both the Justification and Proposed Alternative the following explanation and revisions are provided.
- 1) The third sentence of the third paragraph in the Justification is rewritten as follows:
(Italics denote revised sentence.)
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 XI, Appendix VIII is required. Second, examination scans in two directionsperpendicularto the -weldaxis and two directions parallelto the weld axis or examinationscans as qualified on 100% of the weld volume in accordancewith the performance demonstrationmethodology of Section M7, Appendix VIII is required. Third, to ensure laminar type flaws are detected, a supplemental examination using straight beam is also required.
- 2) Two sentences are added to Paragraph 4(a) of the Proposed Alternative as follows:
(Italics denote the two new sentences.)
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.
Examinationscans shall be infour directions: two beam path directions perpendicularto the weld axis and two beam path directionsparallelto the weld axis.
"Wherethe examination scanperpendicularto 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.
ULNRC-04768 Attachment 2 Page 1 of 6 Request to Use Alternative Ultrasonic Examination Method in Lieu of the Radiography Required by ASME Section 1H1, Subarticle NC-5200
Background:
The 1989 Edition with no Addenda of ASME Section XI 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 IM. 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 III. Pursuant to the provisions of 10CFR 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 III, 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. This table lists the pipe description, weld identification number, nominal pipe size, pipe schedule, and pipe 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 ofNC-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.
ULNRC-04768 Attachment 2 Page 2 of 6 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 XI, Appendix VIII 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..e in accordance with the performance demonstration methodology of Section XI, Appendix_ VIII is 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 ofNC-5330. The acceptance criteria ofNC-5330 specifies acceptable length of an indication only and does 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 transportation, 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.
ULNRC-04768 Attachment 2 Page 3 of 6 (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 o 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 XI, Appendix VIII provided the entire volume of the weld examination is included in the demonstration. 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.
(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,
ULNRC-04768 Attachment 2 Page 4 of 6 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 XI, Appendix VIII, 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.
1 Chemical composition is within the same ranges as requiredin the originalmaterialspecification.
2 Same phase and grain shape as produced by the thermalprocess for the originalspecification.
ULNRC-04768 Attachment 2 Page 5 of 6 (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.
(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 XI Repair/Replacement Plan, as applicable.
- V ULNRC-04768 Attachment 2 Page 6 of 6 Table 1: FeedivaterPipe Welds Description Weld ID No. NPS Sch. Mat.
2-AE-04-F014 14 80 CS 5-Dia. bend & expander upstream of A S/G inlet 2-AE-04-S010-A 14 80 CS 2-AE-04-S010-C 16 80 CS 5-Dia. bend upstream of B S/G inlet 2-AE-04-F030 14 80 CS 2-AE-04-FW8 14 80 CS 2-AE-05-F030 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-F015 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-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 2-AE-04-SO19-A 14 80 CS (B loop) 2-AE-04-FW1O 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