ML050560255
| ML050560255 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/18/2005 |
| From: | Nietmann K Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML050560255 (21) | |
Text
Kevin J. Nietmann 1650 Calvert Cliffs Parkway Plant General Manager Lusby, Maryland 20657 410.495.4101 410.495.4787 Fax Constellation Energy Calvert Cliffs Nuclear Power Plant February 18, 2005 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos. I & 2; Docket Nos. 50-317 & 50-318 ASME Section XI Relief Request to Use Weld Overlay and Associated Alternative Techniques
REFERENCE:
(a) Letter from Ms. M. Gamberoni (NRC) to Mr. C. H. Cruse (BGE), dated April 5, 2000, Safety Evaluation of Proposed Alternate American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)
Section XI, 1998 Edition for the Third 10-Year Inspection Interval -
Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2 (TAC Nos.
MA4647 and MA4648)
Pursuant to 10 CFR 50.55a(a)(3)(i), Calvert Cliffs Nuclear Power Plant, Inc. (CCNPP) hereby proposes alternatives to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) requirements concerning repair/replacement activities for pressure retaining welds subject to Article IWA-4000 in Section XI for the Third Ten-Year Inservice Inspection interval.
Paragraph 50.55a(a)(3)(i) allows the use of alternatives to the requirements of Paragraph 50.55a(g), that provide an acceptable level of quality and safety, when authorized by the Director of the Office of Nuclear Reactor Regulation.
The Third Ten-Year Inservice Inspection Program Plan for Calvert Cliffs Units I and 2 meets the requirements of the 1998 Edition, no Addenda of Section XI of the ASME Code (except for Subsections IWE and IWL), as approved by Nuclear Regulatory Commission (NRC) letter (Reference a).
RELIEF REQUEST Article IWA-4000 of ASME Code, Section Xl, and NRC approved Code Cases N-504-2 and N-638 contain the requirements for structural weld overlay repair activities for unacceptable indications in welded nozzles. Appendix VIII, Supplement 11 of Section XI contains ultrasonic examination requirements for the completed structural weld overlay repair. In lieu of these ASME Code requirements, CCNPP proposes to use alternative techniques for full structural weld overlay repair, and the examination of dissimilar metal weld with unacceptable indications in existing Alloy 82/182 welds.
AXOLV7
Document Control Desk February 18, 2005 Page 2 Similar relief requests have been previously approved for other licensees including AmerGen Energy Company for its Three Mile Island Nuclear Station, Unit I on July 21, 2004. The detailed relief request and the justification are provided in Attachment (I).
SCHEDULE The structural weld overlay is intended as a contingency repair for any flaws identified during examination of dissimilar metal welds in the upcoming Calvert Cliffs Unit 2 Spring 2005 refueling outage (scheduled to begin in late February 2005) and the remainder of the third ten year inservice inspection interval for Units I and 2. We request that the Nuclear Regulatory Commission review and approve our proposed alternative for use during this outage.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours, KJN/GT/bjd
Attachment:
(1) Relief Request To Use Alternative Techniques for Repair and Examination of Unacceptable Indications in Welded Nozzles
Enclosure:
Minimum Chromium Content in Nickel-Alloy Weld Overlays to Mitigate PWSCC cc: C. W. Fleming, Esquire S. J. Collins, NRC J. E. Silberg, Esquire Resident Inspector, NRC R. V. Guzman, NRC R. I. McLean, DNR
ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Calvert Cliffs Nuclear Power Plant, Inc.
February 18, 2005
ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES COMPONENT FOR WHICH RELIEF IS REOUESTED:
Class I dissimilar metal welds, with unacceptable indications attributed to primary water stress corrosion cracking (PWSCC) in existing Alloy 82/182 welds.
CODE REQUIREMENTS FOR WHICH RELIEF IS REOUESTED:
The 1998 Edition no Addenda of American Society of Mechanical Engineers (ASME)Section XI, Article IWA-4000 and Appendix V11I, Supplement 11 and Nuclear Regulatory Commission (NRC) approved Code Cases N-504-2 and N-638. Tables 1-4 provide the specific requirements that are included in this relief request.
PROPOSED ALTERNATIVE AND SUPPORTING INFORMATION:
For dissimilar-metal welds with unacceptable indications in existing Alloy 82/182 welds attributed to PWSCC, a full structural weld overlay modification is proposed. The nozzle material is ferritic steel (either PI or P3 depending on the nozzle). The pipe is austenitic stainless steel (P8). The existing weld filler material is Alloy 82/182 (F43 equivalent to P43). The overlay will be designed as a full structural overlay in accordance with ASME Section XI Code Case N-504-2. The temperbead welding technique will be implemented in accordance with ASME Section XI Code Case N-638 for that portion of the overlay over ferritic base material for which the Construction Code required post-weld heat treatment.
This full structural overlay will satisfy all the structural design requirements of the pipe as if the pipe were not there. As shown in Figure I below, the structural weld overlay (weld reinforcement) will completely cover the existing Alloy 82/182 weld metal and extend onto the ferritic and austenitic stainless steel material on each end. Although the weld overlay will extend the full 3600 around the nozzle, only half is shown in Figure I for clarity.
Figure 1
/- rritic no77ic Structur a l il Existing Alloy 82/182 weld metal overl3y I1Fisting Alloy 821182 weld.
Austcnitic stainless stcel Tables 1, 2, 3, and 4 provide the detailed requirements, the proposed alternatives, and the bases for the alternatives. The modification will be performed as a repair/replacement activity in compliance with IWA-4000 of the 1998 Edition, no Addenda, of ASME Section XI as modified and supplemented in Table 1. Certain requirements of IWA-4000, shown in Table 1, will be accomplished using the methodology of Code CaseN-504-2 (Alternative Rules for Repairs of Classes 1, 2, and 3 Austenitic Stainless Steel Piping) modified as shown in Table 2, and the methodology of Code Case N-638 [Similar and Dissimilar Metal Welding using Ambient Temperature Machine GTAW (Gas Tungsten Arc Welding) Temperbead Technique] modified as shown in Table 3. Ultrasonic examination of the completed structural overlay will be accomplished in accordance with ASME Section XI, Appendix VIII, Supplement II modified to comply with the Performance Demonstration Initiative (PDI) program as shown in Table 4. Any applicable requirements not modified by Tables 1, 2, 3, or 4 will be met as described in IWA-4000, Appendix VIll Supplement I1, and Code Cases N-504-2 and N-638.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Code Case N-504-2 was approved for generic use in Regulatory Guide 1.147, Revision 13, and was developed for austenitic stainless steel material. An alternate application for nickel based and ferritic materials is proposed due to the specific configuration of the subject weldments. Therefore, Calvert Cliffs intends to follow the methodology of Code Case N-504-2, except for the differences identified in Table 2.
Code Case N-638 was approved for generic use in Regulatory Guide 1.147, Revision 13, and was developed for similar and dissimilar metal welding using ambient temperature machine GTAW temperbead technique. Calvert Cliffs intends to follow the methodology of Code Case N-638 for any welding on ferritic or ferritic/austenitic interfaces where the Construction Code required post-weld heat treatment, except for the differences identified in Table 3.
CONCLUSION:
Calvert Cliffs believes the proposed alternatives to Article IWA-4000, Appendix VIII, Supplement 11, and NRC approved Code Cases N-504-2 and N-638, as described in this request, provide an acceptable level of quality and safety.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 1 Modifications to IWA-4000 IWAA4000 Differences/Basis for Relief IWA-4226 Reconciliation of Design Requirements Clarification. The structural weld overlay will be IWA-4311 Material, Design, or Configuration Changes designed to the requirements of ASME Section Xl, Code Case N-504-2 (Alternative Rules for Repair of Classes 1, 2, and 3 Austenitic Stainless Steel Piping). While there is no change to the design requirements of Code Case N-504-2, we are proposing alternatives to some of the requirements as shown in Table 2.
IWA-4410(a) Welding, brazing, metal removal, and Clarification. The Code path for welding on ferritic installation activities shall be performed in accordance material and ferritic/nickel alloy interfaces where with IWA-4420 or IWA-4430, and the other postweld heat treatment was required by the requirements of this Subarticle, except that the Construction Code is as follows. From IWA-4410(a),
requirements of IWA-4700 shall be used for heat we have chosen the option of IWA-4430 from which we exchanger tube plugging or sleeving. invoke IWA-4600. IWA-4600(b) invokes IWA-4630 IWA-4430 In lieu of the requirements of IWA-4420, (dissimilar metal weld requirements) and IWA-4610 the requirements of IWA-4600 may be used for (general requirements). We chose the methodology of alternative welding methods. Code Case N-638 as an alternative to IWA-4630. Code Case N-638 is accepted without restriction in the current IWA-4600(b) When postwveld heat treatment is not to NRC Regulatory Guide 1.147. WVelding wvill be be performed, the following provisions may be used. pRfoRedunacordance with WA-ding as m e (I) The welding methods of IWA-4620, IWA-4630, or performed (T accordance meth IWAo46dO as modified by IWA-4640 may be used in lieu of the welding and N-638 as modified by Table 3. Welding will also meet nondestructive examination (NDE) requirements of the Code Case N-N04-2 as modified by Table 2.
Construction Code or Section 111, provided the requirements of IWA-4610 are met. Clarification. If the Construction Code did not require postweld heat treatment, welding will be performed in accordance with IWA-4420 and Code Case N-504-2 as modified by Table 2. Code Case N-638 and the modifications of Table 3 would not apply.
IWA-4610(a) The area to be welded plus a band around Clarification. IWA-4610(a) contains two general the area of at least 1-1/2 times the component thickness requirements, 1) preheat and interpass temperature or 5 in. (127 mm), whichever is less, shall be preheated criteria and 2) a requirement to monitor process and maintained at a minimum temperature of 350'F temperatures with thermocouples and recording (1771C) for the SMAW process and 300'F (1491C) for instruments. The preheat and interpass temperature the GTAW process during welding. The maximum criteria are superceded by Code Case N-638 so no Relief interpass temperature shall be 450'F (2320 C). is requested for this requirement.
Thermocouples and recording instruments shall be used Relief. In lieu of weld-attached thermocouples and to monitor the process temperatures. Their attachment recording instruments, we plan to monitor the process and removal shall be in accordance with Section Ill. temperatures with non-attached devices, e.g., contact Code Case N-638 pyrometers or temperature indicating crayons and 4.0(c) Areas from which weld-attached thermocouples provide a manual record of the process temperatures.
have been removed shall be ground and examined using Code Case N-638 requires a minimum preheat a surface examination method. temperature of 50'F and a maximum interpass temperature of 3501F. Code Case N-638 also refers to weld-attached thermocouples in paragraph 4.0(c). Due to the heat sink of the structural overlay, we believe the actual process temperatures will be comfortably within these limits and propose demonstrating this on mockups.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 1 Modifications to IWA-4000
~-;-
,; IWA.40i;- -- : -
. IWA4000-
- . -..Differences/Basis i- . re-. Rlef --
forRelief -
The mockups will be of substantially smaller heat sink than the production weld so the mockup demonstration will be conservative, i.e., the mockups will experience greater temperature excursions than the production weld.
NPS 2 overlays will most likely be water backed. NPS 4 and NPS 12 overlays will most likely not be water backed. Both water backed and non water backed applications will be evaluated on the mockups. The production weld will be monitored at regular intervals with contact pyrometers and/or temperature indicating crayons and a record will be kept. Weld-attached thermocouples would result in significant radiation dose during installation, their subsequent removal, and NDE of the attachment surfaces.
IWA-4422.1 Defect Removal Clarification. In lieu of the defect excavation (a) The metal removal process shall be in accordance requirements of IWA-4422.1 and IWA-461 1.1, the with IWA-4421, except that thermal removal structural overlay will be performed in accordance with processes shall be in accordance with IWA-4460. A Code Case N-504-2 as modified and supplemented by defect is considered removed when it has been Table 2. IWA-4422.1 is required when temperbead reduced to an acceptable size. The component shall welding is not used. IWA-461 1.1 is required when be acceptable for continued service if the resulting temperbead welding is used.
section thickness created by the cavity is at least the minimum required thickness. If the resulting section thickness is less than the minimum required thickness, the component shall be corrected by repair/replacement activities in accordance with this Article.
IWA-4611 METAL REMOVAL IWA-4611.1 General Requirements (a) Defects shall be removed or reduced in size in accordance with this Paragraph. The component shall be acceptable for continued service if the resultant section thickness created by the cavity is at least the minimum design thickness. If the resulting section thickness is less than the minimum design thickness, the component shall be corrected by repair/replacement activities in accordance with this Article. Alternatively...Section III.
(b) The original defect shall be removed:
(2) when welding is required in accordance with IWVA-4630 or IWA-4640, and the defect penetrates the base material.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 1 Modifications to IWA-4000 IWA4000 Differences/Basis for Relief IWA-4520 Examination Clarification. The Construction Code for this (a) Welding or brazing areas and welded joints made for repair/replacement activity will be the methodology of installation of items shall be examined in accordance Code Cases N-504-2 and N-638 modified as shown in with the Construction Code identified in the Tables 2 and 3, respectively. Therefore, the Repair/Replacement Plan. Construction Code examination will be as described in Tables 2 and 3.
IWA-4540 PRESSURE TESTING OF CLASS 1, 2, Clarification. In lieu of the pressure testing AND 3 ITEMS requirements of IWA-4540, the completed structural (a) After welding on a pressure retaining boundary or overlay will be pressure tested in accordance with the installation of an item by welding or brazing, a system requirements of Code Case N-504-2, paragraph (h).
hydrostatic test shall be performed in accordance with IWA-5000.
(b) The following may be exempted from the system hydrostatic tests:
(3) piping, pump, and valve welding that does not penetrate through the pressure boundary.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 2 Modifications to Code Case N-504-2 Code Case N-504-2 Differences/Basis for-Relief Reply: It is the opinion of the Committee that, in Relief. We propose to apply Code Case N-504-2 to the lieu of the requirements of IWA-4120 in Editions ferritic (PI or P3) and nickel alloy (F43/P43) base material and Addenda up to and including the 1989 Edition as well as the austenitic stainless steel (P8) base material.
with the 1990 Addenda, in IWA-4170(b) in the Code Case N-504-2 is accepted without restriction in the 1989 Edition with the 1991 Addenda up to and current NRC Regulatory Guide 1.147. The base material including the 1995 Edition, and in IWA-4410 in the will be ferritic material (PI or P3) with existing nickel alloy 1995 Edition with the 1995 Addenda and later weld metal (F43/P43) to which an austenitic stainless steel Editions and Addenda, defect in austenitic stainless (P8) pipe is welded. Industry operational experience has steel piping may be reduced to a flaw of acceptable shown that PWSCC in Alloy 82/182 will blunt at the size in accordance with IWB-3640 from the 1983 interface with stainless steel base metal, ferritic base metal, Edition with the Winter 1985 Addenda, or later or Alloy 52/52M/I 52 weld metal. Calvert Cliffs plans to Editions and Addenda, by deposition of weld apply a 3600, full structural weld overlay to control growth in reinforcement (weld overlay) on the outside surface any PWSCC crack and maintain weld integrity. The weld of the pipe, provided the following requirements are overlay will put compressive stress around the weldment, met: thus impeding growth of any existing crack and therefore, will fulfill all structural requirements, independent of the existing weld.
(b) Reinforcement weld metal shall be low carbon Relief. In lieu of austenitic stainless steel filler material, the (0.035% max.) austenitic stainless steel applied reinforcement weld metal will be a nickel alloy.
360° around the circumference of the pipe, and shall The weld metal will be either ERNiCrFe-7 (Alloy 52, be deposited in accordance with a qualified welding UNS N06052) or ERNiCrFe-7A (Alloy 52M, UNS N06054).
procedure specification identified in the Repair ENiCrFe-7 may be used to SMAW seal weld the initial base Program. metal surfaces or to perform repair on the weld reinforcement. These weld metals are assigned F43 by ASME per Code Case 2142-2. Alloy 52MS may also be used. Alloy 52MS is a trade designation for Alloy 52M with additional cleaning requirements during manufacture and meets all requirements of Alloy 52M. The requirements of ASME Section III, NB-2400 will be applied to all filler material.
This filler material was selected for its improved resistance to PWSCC. Alloys 52, 52M, and 152 all contain about 30%
chromium that imparts excellent corrosion resistance. The existing Alloy 82/182 weld and the Alloy 52/52M overlay are austenitic and have ductile properties and toughness similar to austenitic stainless steel piping welds at pressurized water reactor operating temperature. These filler materials are suitable for welding over the ferritic nozzle, Alloy 82/182 weld and the austenitic stainless steel piping.
(NOTE: ERNiCrFe-7 and ENiCrFe-7 are assigned F number 43 by the 2004 Edition of ASME Section IX.
ERNiCrFe-7A (UNS N06054) is assigned F number 43 by Boiler and Pressure Vessel Code Case 2142-2.)
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 2 Modifications to Code Case N-504-2 Code Case N-504-2 -Differences/Basis for Relief (e) The weld reinforcement shall consist of a Relief. Delta ferrite (FN) measurements will not be minimum of two weld layers having as-deposited performed for this overlay because welds of Alloy delta ferrite content of at least 7.5 FN. The first 52/52M/1 52 are 100% austenitic and contain no delta ferrite layer of weld metal with delta ferrite content of least due to the high nickel composition (approximately 60%
7.5 FN shall constitute the first layer of the weld nickel).
reinforcement design thickness. Alternatively, first Relief. In lieu of the minimum two weld layers, mockups layers of at least 5 FN may be acceptable based on will be used to identify the first weld layer on which a 24%
evaluation. minimum Cr content is achieved over the ferritic, Alloy 82/182, and stainless steel base materials.
Enclosure I provides justification for the 24% minimum chromium content as an effective barrier to growth of a PWSCC crack. The mockup-developed layer containing 24% minimum chromium over all three base metals will constitute the first layer of the weld reinforcement design thickness and may or may not be the second weld layer.
It is recognized that the initial layers can be alloy rich or base material rich, depending on the welding parameters. The initial weld layer(s) will have an intermediate composition lying between that of the base material and the Alloy 52/52M/152 weld metal compositions due to dilution. The bead composition is dependent upon welding variables, such as heat input, wire feed, and travel speed. The production structural overlay will be performed with the welding parameters used in the mockups to achieve the same nominal chemical composition as in the mockups. Chemical composition testing will not be performed on the production structural overlay.
(i) Preservice examination of the completed repair Clarification. Ultrasonic examination will be in accordance shall be performed in accordance with IWB-2200. with ASME Section Xl, Appendix VITT, Supplement 11, For all classes of components, liquid penetrant, and Qualification Requirements for Full Structural Overlaid ultrasonic examination of the completed weld repair Wrought Austenitic Piping Welds as implemented through shall be performed. Examination procedures shall the PDI program. The Relief necessary to use the PDI be specified in the repair program. The acceptance overlay program is described in Table 4.
standards of Table IWB-3514-2 shall apply. The weld overlay will be added to the inservice inspection Ultrasonic examinations shall verify the integrity of plan and will be ultrasonically examined during the first the newly applied weld reinforcement. refueling outage following the application.
Examinations shall also be performed to identify the refuel outag foll te appicatin.
The wveld overlay willorbeexisting ultrasonically examined to original flaws the outer 25% of the underlying orgialflwsin determine if any new flaws have propagated into pipe wall as a benchmark for subsequent the upper 25% of the pipe base material or into the overlay.
examinations of the overlay. Grinding and The angle beam will be directed perpendicular and parallel to machining of the as-welded overlay surface may be the pipe axis, with scanning performed in four directions.
used to improve the surface finish for such examinations, when the overlay thickness is not Weld overlays that show no indication of flaw growth or new reduced below design requirements. flaws will be placed into a population to be examined on a (I)Nondestructive examinations shall include the sample basis. Twenty-five percent of this population shall be weld and volume identified in (i) above. examined once every ten years.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 2 Modifications to Code Case N-504-2 Code Case N-504-2; - Differences/Basis for Relief If the inservice inspection examinations reveal flaw growth or new flaws, meeting the acceptance standards, the weld overlay will be re-examined during the first refueling outage following the discovery of the flaw growth or new flaws.
Weld overlays that show no additional indications of flaw growth or new flaws will be re-inspected once every ten years.
American Society of Mechanical EngineersSection XI, Appendix P represents incorporation of Code Case N-504-2 into the Code. Appendix P has not yet been approved but provides more specific guidance on preservice and inservice inspection of weld overlays than Code Case N-504-2. The above criteria is more restrictive than Appendix P in that it requires re-examination of the weld overlay the first outage following its application and when flaw growth or new flaws are found. It also requires re-examination once every ten years of all overlays when they have been found to show additional flaws or flaw growth. Appendix P would allow these flaws to be examined using a 25% sample if re-examination found flaw growth to have stopped.
(I) All other applicable requirements of IWA-4000 Relief. In lieu of the ultrasonic examination acceptance and IWB-4000, IWC-4000, or IWD-4000 shall be criteria of the Construction Code, the following acceptance met. criteria will be used.
Planar indication(s) detected during ultrasonic examination will be evaluated in accordance with Table IWB-3514-2 of ASME Section Xl.
Laminar indication(s) detected during ultrasonic examination will be evaluated in accordance with Table IWB-3514-3 of ASME Section XI, and the following items:
. Laminar indications not located at the pipe/overlay interface may require evaluation to IWB-3514-2.
- Laminar indications shall permit examination of at least 90% of the examination volume and shall not interfere with interrogation of the base material examination volume.
- The size of the lamination as it relates to the total size of the overlay.
- The above acceptance criteria will be used for subsequent inservice inspection of the weld overlay(s).
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 3 Modifications to Code Case N-638 Code Case N-638 Differences/Basis for Relief Reply: It is the opinion of the Committee that repair to Relief. We propose to weld on non water backed as P-No. 1, 3, except SA-302 Grade B, 12A, 12B, and 12C well as water backed components.
material and their associated welds and P No. 8 or P The phrase "when it is impractical, for operational or No. 43 material to P-Nos. 1, 3, except SA-302 GradeB, radiological reasons, to drain the component" limits 12A, 12B, and 12C material and their associated welds, application to water backed components. The may be made by the automatic or machine GTAW proposed repair(s) may be to either/both water backed temperbead technique without the specified preheat or and non water backed components. We believe postweld heat treatment of the Construction Code, when it restriction to water backed components was an is impractical, for operational or radiological reasons, to oversight in Code Case N-638 since Code Case drain the component, and without the NDE requirements of N-638-1 permits non water backed applications (with the Construction Code, provided the requirements of no other change over Code Case N-638). Code Case paragraphs 1.0 through 5.0, and all other requirements of N-638-1 is not yet approved for generic use in NRC IWA-4000, are met. Regulatory Guide 1.147. Mockups of the structural overlay will be performed on both water backed and non water backed samples to validate parameters for both situations.
1.0(a) The maximum area of an individual weld based on Relief. We propose to exceed the 100 in2 limitation the finished surface shall be 100 in2, and the depth of the when necessary.
weld shall not be greater than one-half of the ferritic base Application of Code Case N-638 will be on the ferritic metal thickness. portion of the base material extending onto the existing F43 buttering a minimum of 1/8 inch [to satisfy 1.0(b)]. Depending on the diameter of the nozzle to be overlaid (NPS 2, NPS 4, or NPS 12) and the axial extent of the overlay onto the ferritic material, the 100 in2 limit may be exceeded.
Additional axial extent onto the ferritic material may be necessary to facilitate ultrasonic examination and/or to ensure a smooth final nozzle contour.
Studies by Structural Integrity (SI), Electric Power research Institute (EPRI), and others indicate the 100 in2 limitation is arbitrary and repair areas to at least 500 in2 have no adverse effect. Activity is underway in ASME Section XI, Working Group-Welding to develop a white paper generically justifying temperbead welds of greater than 100 in2.
Clarification. We interpret the depth of the weld requirement as applicable to excavation and repair of flaws in the ferritic material. The structural overlay is to repair flaws in the Alloy 82/182 material. Use of temperbead welding is solely to facilitate extending the structural overlay onto ferritic material which would otherwise require postweld heat treatment.
Extending the overlay onto ferritic material is necessary to meet the configuration requirements of 9
ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 3 Modifications to Code Case N-638 Code Case N-638 Differences/Basis for Relief Code Case N-504-2, to enable volumetric examination, to ensure a smooth nozzle contour, and to cover the entire Alloy 82/182 surface.
4.0(b) The final weld surface and the band around the area Clarification. Appendix I leads to Appendix Vill.
defined in paragraph 1.0(d) shall be examined using a Ultrasonic examination will be in accordance with surface and ultrasonic methods when the completed weld ASME Section XI, Appendix VIll, Supplement 11, has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The Qualification Requirements for Full Structural ultrasonic examination shall be in accordance with Overlaid Wrought Austenitic Piping Welds as Appendix 1.3 implemented through the PDI program. The Relief 3 Refer to the 1989 Edition with the 1989 Addenda and later necessary to use the PDI overlay program is described in Table 4. Ultrasonic examination is also consistent R and Addenda. wite Editions Edition Addendaa with the requirements of Code Case N-504-2 as discussed in Table 2. The 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> hold will be met.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Appendix VIII of Section XI cannot be used for the structural weld overlay required NDE. Relief is requested to use the PDI program implementation of Appendix VIII. A detailed comparison of Appendix VIII and PDI requirements is summarized belowv.
At this time, the Performance Demonstration Initiative has not qualified procedures for weld overlays less than 4 inch diameter. We propose to use the existing PDI procedures (for greater than or equal to 4 inch diameter) on weld overlays less than 4 inch diameter down to 2 inch diameter. The proposed methods of examination of weld overlays less than NPS 4 will ensure that we find any flaws of significance in the weld overlay. The basis for this conclusion is that the techniques have been demonstrated on samples of greater than and equal to 4 inch diameter weld overlays. Personnel qualified on 4 inch diameter weld overlays will be used to examine weld overlays less than 4 inch diameter. Once qualified procedures are developed for weld overlays less than 4 inch diameter, the qualified procedures will be used, along with personnel qualified on such procedures.
Relief is requested to allow closer spacing of flaws provided they don't interfere with detection or discrimination. The specimens used to date for qualification to the Tri-party (NRC/BWROG/EPRI) agreement have a flaw population density greater than allowed by current Code requirements. These samples have been used successfully for all previous qualifications under the Tri-party agreement program. To facilitate their use and provide continuity from the Tri-party agreement program to Supplement I 1, the PDI program has merged the Tri-party test specimens into their weld overlay program.
Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT II -QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS 1.0 SPECIMEN REQUIREMENTS 1.1 General. The specimen set shall conform to the following requirements.
(b) The specimen set shall consist of at least three (b) .. The specimen set shall include specimens with specimens having different nominal pipe diameters and overlays not thicker than 0.1 in. more than the minimum overlay thicknesses. They shall include the minimum thickness, nor thinner than 0.25 in. of the maximum and maximum nominal pipe diameters for which the nominal overlay thickness for which the examination examination procedure is applicable. Pipe diameters procedure is applicable.
within a range of 0.9 to 1.5 times a nominal diameter To avoid confusion, the overlay thickness tolerance shall be considered equivalent. If the procedure is containedin the last sentence was rewordedand the applicable to pipe diameters of 24 in. or larger, the phrase "andthe remaindershall be alternativefla'vs" specimen set must include at least one specimen 24 in. was added to the next to last sentence in paragraph or larger but need not include the maximum diameter. .I(d)().
The specimen set must include at least one specimen with overlay thickness within -0.1 in. to +0.25 in. of the maximum nominal overlay thickness for which the procedure is applicable.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT 11 -QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS (d) FlaivConditions (1) Base metalflanvs. All flaws must be cracks in or (I) ...must be in or... intentional overlay fabrication near the butt weld heat-affected zone, open to the inside flaws shall not interfere with ultrasonic detection or surface, and extending at least 75% through the base characterization of the base metal flaws. Specimens metal wall. Flaws may extend 100% through the base containing intergranular stress corrosion cracking shall metal and into the overlay material; in this case, be used when available. At least 70% of the flaws in the intentional overlay fabrication flaws shall not interfere detection and sizing tests shall be cracks and the with ultrasonic detection or characterization of the remainder shall be alternative flaws. Alternative flaw cracking. Specimens containing intergranular stress mechanisms, if used, shall provide crack-like reflective corrosion cracking shall be used when available. characteristics and shall be limited by the following:
(a) The use of alternative flaws shall be limited to when the implantation of cracks produces spurious reflectors that are uncharacteristic of actual flaws.
(b) Flaws shall be semi elliptical with a tip width of less than or equal to 0.002 inches.
This paragraphrequires that all base metalflaws be cracks. Implanting a crack requires excavation of the base materialon at least one side ofthe flaw While this may be satisfactoryforferriticmaterials, it does not produce a useable axialflaw in austenitic materials because the sound beam, which normallypasses only through base material, must now travel through weld material on at least one side, producingan unrealistic flaw response. To resolve this issue, the PD!program revised this paragraphto allow use of alternativeflawv mechanisms under controlledconditions. For example, alternativeflawsshall be limited to when implantation of cracks precludes obtainingan effective ultrasonic response,flaws shall be semi ellipticalwith a tip width of less than or equal to 0.002 inches, and at least 70% of the flaws in the detection and sizing test shall be cracks and the remaindershall be alternativeflaws.
To avoid confusion, the overlay thickness tolerance contained in paragraph1I (b) lastsentence, was rewordedandthe phrase "andthe remaindershall be alternativeflcnvs" wvas added to the next to last sentence.
Paragraph1.I (d)(l) includes the statement that intentionaloverlayfabricationflawsshallnot interfere with ultrasonicdetection or characterizationofthe base metalflavs.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT II-QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS (e) DetectionSpecimens (1) At least 20% but less than 40% of the flaws shall be (1) At least 20% but less than 40% of the base metal oriented within +200 of the pipe axial direction. The flaws shall be oriented within +20° of the pipe axial remainder shall be oriented circumferentially. Flaws direction. The remainder shall be oriented shall not be open to any surface to which the candidate circumferentially. Flaws shall not be open to any surface has physical or visual access. The rules of IWA-3300 to which the candidate has physical or visual access.
shall be used to determine whether closely spaced flaws The requirementforaxially orientedoverlayfabrication should be treated as single or multiple flaws. flawvs lvas excludedfrom the PDI Programas an improbablescenario. Meld overlays aretypically appliedusing automatedGTA IVtechniques with thefiller metal appliedin a circumferentialdirection. Because resultantfabricationinduceddiscontinuities would also be expected to have major dimensions orientedin the circumferentialdirection axial overlayfabricationflaws are unrealistic.
The requirementfor using lIWA-3300for proximityflaw evaluation was excluded, Instead indications till be sized based on their individual merits (2) Specimens shall be divided into base and over-lay (2) Specimens shall be divided into base metal and grading units. Each specimen shall contain one or both overlay fabrication grading units. Each specimen shall types of grading units. contain one or both types of grading units. Flaws shall not interfere with ultrasonic detection or characterization of other flaws.
(a)fl) A base grading unit shall include at least 3 in. of (a)(I)A base metal grading unit includes the overlay the length of the overlaid weld. The base grading unit material and the outer 25% of the original overlaid weld.
includes the outer 25% of the overlaid weld and base The base metal grading unit shall extend metal on both sides. The base grading unit shall not circumferentially for at least I in. and shall start at the include the inner 75% of the overlaid weld and base weld centerline and be wide enough in the axial direction metal overlay material, or base metal-to-overlay to encompass one half of the original weld crown and a interface. minimum of 0.50" of the adjacent base material.
Thephrase "and base metal on both sides," was inadvertently included in the descriptionofa base metal gradingunit. The PD!program intentionally excludes this requirement becausesome of the qualification samples includeflawvs on both sides of the weld To avoid confusion several instances of the term "cracks" or "cracking" wvere changedto the term 'flaws "
because of the use of alternativeflaw mechanisms.
Modified to require that a base metal gradingunit include at least I in. of the length of the overlaidweld, ratherthan 3 inches.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT 11-QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS (a)(2) When base metal cracking penetrates into the (a)(2) When base metal flaws penetrate into the overlay overlay material, the base grading unit shall include the material, the base metal grading unit shall not be used as overlay metal within 1 in. of the crack location. This part of any overlay fabrication grading unit.
portion of the overlay material shall not be used as part of any overlay grading unit.
(a)(3) When a base grading unit is designed to be (a)(3) Sufficient unflawed overlaid weld and base metal unflawed, at least I in. of unflawed overlaid weld and shall exist on all sides of the grading unit to preclude base metal shall exist on either side of the base grading interfering reflections from adjacent flaws.
unit. The segment of weld length used in one base Modified to require sufficient unflawed overlaidweld grading unit shall not be used in another base grading andbase metal to exist on all sides of the grading unit to unit. Base grading units need not be uniformly spaced preclude interferingreflectionsfrom adjacentflaws, around the specimen. ratherthan the I inch requirement.
(b)(1) An overlay grading unit shall include the overlay (b)(l) An overlay fabrication grading unit shall include material and the base metal-to-overlay interface of at the overlay material and the base metal-to-overlay least 6 in2. The overlay grading unit shall be rectangular, interface for a length of at least I in.
with minimum dimensions of 2 in. Modified to define an overlayfabricationgrading unit as including the overlay materialand the base metal-to-overlay interfacefor a length of at least I in, ratherthan the 6 in2 requirement (b)(2) An overlay grading unit designed to be unflawed (b)(2) Overlay fabrication grading units designed to be shall be surrounded by unflawed overlay material and unflawed shall be separated by unflawed overlay material unflawed base metal-to-overlay interface for at least and unflawed base metal-to-overlay interface for at least I in. around its entire perimeter. The specific area used I in. at both ends. Sufficient unflawed overlaid weld and in one overlay grading unit shall not be used in another base metal shall exist on both sides of the overlay overlay grading unit. Overlay grading units need not be fabrication grading unit to preclude interfering reflections spaced uniformly about the specimen. from adjacent flaws. The specific area used in one overlay fabrication grading unit shall not be used in another overlay fabrication grading unit. Overlay fabrication grading units need not be spaced uniformly about the specimen.
Paragraph1.I(e) (2) (b) (2) states that overlay fabrication grading units designedto be unflawedshall be separated by unflawed overlay materialand unflawved base metal-to-overlay interfaceforat least I in. at both ends, rather than aroundits entireperimeter.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT II-QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS (b)(3) Detection sets shall be selected from ... base metal grading units, ten unflawed base metal Table VIII-S2-1. The minimum detection sample set is grading units, five flawed overlay fabrication grading five flawed base grading units, ten unflawed base units, and ten unflawed overlay fabrication grading units.
grading units, five flawed overlay grading units, and ten For each type of grading unit, the set shall contain at least unflawed overlay grading units. For each type of twice as many unflawed as flawed grading units. For grading unit, the set shall contain at least twice as many initial procedure qualification, detection sets shall unflawed as flawed grading units. include the equivalent of three personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.
69 Sizing Specimen (I) The minimum number of flaws shall be ten. At least (I) The .... least 40% of the flaws shall be open to the 30% of the flaws shall be overlay fabrication flaws. At inside surface. Sizing sets shall contain a distribution of least 40% of the flaws shall be cracks open to the inside flawv dimensions to assess sizing capabilities. For initial surface. procedure qualification, sizing sets shall include the equivalent of three personnel qualification sets. To qualify new values of essential variables, at least one personnel qualification set is required.
(3) Base metal cracking used for length sizing (3) Base metal flaws used ... circumferentially.
demonstrations shall be oriented circumferentially.
(4) Depth sizing specimen sets shall include at least two (4) Depth sizing specimen sets shall include at least two distinct locations where cracking in the base metal distinct locations where a base metal flaw extends into extends into the overlay material by at least 0.1 in. in the the overlay material by at least 0.1 in. in the through-wall through-wall direction. direction.
2.0 CONDUCT OF PERFORMANCE DEMONSTRATION The specimen inside surface and identification shall be The specimen.....prohibited. The overlay fabrication concealed from the candidate. All examinations shall be flaw test and the base metal flaw test may be performed completed prior to grading the results and presenting the separately.
results to the candidate. Divulgence of particular specimen results or candidate viewing of unmasked specimens after the performance demonstration is prohibited.
2.1 Detection Test.
Flawed and unflawed grading units shall be randomly Flawed.... (base metal or overlay fabrication) ... each mixed. Although the boundaries of specific grading specimen.
units shall not be revealed to the candidate, the candidate shall be made aware of the type or types of grading units (base or overlay) that are present for each specimen.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT II-QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS 2.2 Length Sizing Test (d) For flaws in base grading units, the candidate shall (d) For ... base metal grading ... base metal wall estimate the length of that part of the flaw that is in the thickness.
outer 25% of the base wall thickness.
2.3 Depth Sizing Test.
For the depth sizing test, 80% of the flaws shall be sized (a) The depth sizing test may be conducted separately or at a specific location on the surface of the specimen in conjunction with the detection test.
identified to the candidate. For the remaining flaws, the (b) When the depth sizing test is conducted in regions of each specimen containing a flaw to be sized conjunction with the detection test and the detected flaws shall be identified to the candidate. The candidate shall do not satisfy the requirements of 1.1(f), additional determine the maximum depth of the flaw in each specimens shall be provided to the candidate. The region. regions containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.
(c) For a separate depth sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.
3.0 ACCEPTANCE CRITERIA 3.1 Detection Acceptance Criteria Examination procedures, equipment, and personnel are Examination procedures are qualified for detection when:
qualified for detection when the results of the a. All flaws within the scope of the procedure are performance demonstration satisfy the acceptance detected and the results of the performance criteria of Table Vill-S2-1 for both detection and false demonstration satisfy the acceptance criteria of calls. The criteria shall be satisfied separately by the Table Vlll-S2-1 for false calls.
demonstration results for base grading units and for b. At least one successful personnel demonstration has overlay grading units. been performed meeting the acceptance criteria defined in (c).
- c. Examination equipment and personnel are qualified for detection when the results of the performance demonstration satisfy the acceptance criteria of Table VIll-S2-I for both detection and false calls.
- d. The criteria in (b) and (c) shall be satisfied separately by the demonstration results for base metal grading units and for overlay fabrication grading units.
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ATTACHMENT (1)
RELIEF REQUEST TO USE ALTERNATIVE TECHNIQUES FOR REPAIR AND EXAMINATION OF UNACCEPTABLE INDICATIONS IN WELDED NOZZLES Table 4 Modifications to Appendix VIII, Supplement 11 SUPPLEMENT 11 - QUALIFICATION PDI PROGRAM:
REQUIREMENTS FOR FULL STRUCTURAL The Proposed Alternative to OVERLAID WROUGHT AUSTENITIC PIPING Supplement 11 Requirements WELDS 3.2 Sizing Acceptance Criteria (a) The RMS error of the flaw length measurements, as (a) The ... base metal flaws is ... position.
compared to the true flaw lengths, is less than or equal to 0.75 inch. The length of base metal cracking is measured at the 75% through-base-metal position.
(b) All extensions of base metal cracking into the This requirement is omitted.
overlay material by at least 0.1 in. are reported as being The requirementfor reportingall extensions of cracking intrusions into the overlay material. into the overlay is omittedfront the PDIProgram because it is redundant to the RMS calculations performed in paragraph3.2(c) and its presence adds confusion andambiguity to depth sizing as requiredby paragraph3.2(c). This also makes the wield overlay program consistent with the Supplement 2 depth sizing criteria.
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ENCLOSURE 1 MINIMUM CHROMIUM CONTENT IN NICKEL-ALLOY WELD OVERLAYS TO MITIGATE PWSCC Calvert Cliffs Nuclear Power Plant, Inc.
February 18, 2005