ML20112H517
| ML20112H517 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/11/1996 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9606180255 | |
| Download: ML20112H517 (12) | |
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Southctn Nuctser Operatng company Post Offica Box 1295 Birmingham. Alabama 35201 Te!ephone (205) 868-5131 L
Southem Nudear Operating Company o.v. uor.y Vee President Fariey Project the Southem elecinC System June 11, 1996 Docket Nos.: 50-348 10 CFR 50.55 50-364 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 d
Joseph M. Farley Nuclear Plant i
Revised Request for Use of Alternative Rules For Post Repair / Replacement Hydrostatic Testing for ASME Class 1. 2. and 3 Systems Based on ASME Code Case N-416-1 Ladies and Gentlemen:
On January 12,1996, Southern Nuclear Operating Company (SNC) submitted a relief request in accordance with 10 CFR 50.55a(a)(3)(i) to propose the use of American Society of Mechanical Engineers (ASME)Section XI Code Case N-416-1 as an alternative that would allow the performance of system leakage tests following maintenance and modification activities in lieu of hydrostatic pressure tests. Subsequently, the NRC telephoned SNC on February 29,1996, and requested additional information concerning three items on this relief request. The NRC asked that SNC provide further detail of the hardship associated with these three items.
The three items are as follows:
- 1. Use of the 1971 edition of the ASME Section III Code for nondestructive examination requirements instead of the 1992 edition referenced in the Code Case.
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- 2. Use of the 1983 edition of the ASME Section XI Code for system leakage test
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I requirements instead of the 1992 edition referenced in the Code Case.
- 3. Performance of a root pass surface examination on all class 3 welds as an additional requirement to ASME Code Case N-416-1.
Attached to this letter is the SNC response to the NRC request for additional information.
Also enclosed are the revised relief requests and a copy of Code Case N-416-1.
NRC approval is requested by September 1,1996, in order to support activities associated with the 1996 Fall Unit 2 Refueling Outage.
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U. S. Nuclear Regulatory Commission Page 2 Should you have any questions in this regard, please contact this office.
Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY ffAt},po Dave Morey EFB/ cit:CC416REV. DOC Attachment
Enclosures:
- 1. Unit 1 Relief Request
- 2. Unit 2 Relief Request
- 3. ASME Code Case N-416-1 cc:
Mr. S. D. Ebneter, Region II Administrator Mr. B. L. Siegel, NRR Senior Project Manager Mr. T. M. Ross, FNP Sr. Resident Inspector
e s o e ATTACIIMENT SNC RESPONSE TO ADDITIONAL INFORMATION REQUESTED FOR USE OF ASME CODE CASE N416-1
4 4 ATTACIIMENT i SNC RESPONSE TO ADDITIONAL INFORMATION REQUESTED FOR USE OF ASME CODE CASE N416-1 1. Use of the 1971 edition of the ASME Section III Code for nondestructive examination i requirements instead of the 1992 edition referenced in the Code Case. SNC Response: ] SNC withdraws its request for use of the 1971 Code. 2. Use of the 1983 edition of the ASME Section XI Code for system leakage test i requirements instead of the 1992 edition referenced in the Code Case. ) SNC Response: SNC withdraws its request for use of the 1983 Code. 3. Performance of a root pass surface examination on all class 3 welds as an additional requirement to ASME Code Case N-416-1. During ASME Code committee sessions concerning this Code Case, the performance of a j surface examination for all class 3 welds was discussed. It was determined by the committee i that performance of this examination would not result in a compensating increase in the level of quality or safety, and therefore this requirement was not included in the final version of the Code Case approved by ASME. SNC is aware that the NRC has subsequently added the requirement for a root pass examination as a condition when approving the Code Case for use by licensees. SNC is in agreement with the ASME Code Case as written without the additional surface examination requirement and offers the following asjustification. SNC has reviewed the potential cost and benefit of performing the additional surface examination. SNC has detennined that the probability of this examination having any added value is extremely low due to the following: 1. The surface of the root pass layer is physically fused into the subsequent weld pass. Therefore, weld passes performed subsequent to the root pass will alter the surface of the root pass weld which was examined effectively rendering the examination irrelevant in most cases. 2. Any significant surface defects in the root pass weld would be discovered by the welder himself or supervisor by visual examination of the weld. In addition, FNP procedures require an independent visual examination of Class 3 weld root passes by a qualified inspector A-1 i J
P SNC offers the following to demonstrate the burden imposed by requiring a surface examination on the root pass for the applicable Class 3 welds: 1. Work productivity will be adversely impacted due to the interruption in welding and the time required to perform surface examination of the root pass. This will affect the schedule of all work which requires these additional examinations. If the activity is on critical path, the cost for the work interruptions is greater than $10,000 per hour. 2. Conducting the additional examinations and evaluating the results will require SNC to train and certify additional personnel or hire additional contractors. 3. Potential adverse effects due to the interruption of the welding sequence (i.e. discontinuing preheat and cooling a thin weld cross-section to perform a surface exam) outweigh the value of a root pass surface exvnination. 4. Procedural changes to require the new examination to be performed will have to be prepared, reviewed, approved, distributed, and filed for record purposes. 5. Training will be necessary to ensure the new requirements are met. SNC offers the following as furtherjustification for not performing the root pass PT: 1. Requiring a surface examination of the root pass on all class 3 welds imposes more stringent requirements on certain class 3 welds than on similar class 2 welds. 2. SNC disputes the usefulness of the surface examination of the root pass on all types of welds as a reliable means of detecting potential crack initiating weld root conditions such as lack of fusion, incomplete penetration and root concavity or convexity. The root pass surface examination does not add any value in identifying these conditions. In conclusion, SNC believes that the imposition of the additional root pass surface examination on the class 3 welds presents a hardship which does not result in a compensating increase in the level of quality or safety. SNC is therefore requesting the adoption of the alternative mies of the code case without imposition of any additional class 3 nondestructive examination requirements. A-2
I FNP-1-M-043 RELIEF REQUEST FNP-1 i RR-47 i COMPONENT OR RELIEF AREA: All ASME Class 1,2, and 3 piping and components. REQUIREMENT FROM WHICH RELIEF IS REQUESTED: The 1983 Edition through Summer 1983 addenda, Section XI, IWA-4400(a) requires that a system hydrostatic test be performed in accordance with IWA-5000 after a welded repair on a pressure retaining boundary. BASIS FOR RELIEF: Reliefis requested from performing this Code required post repair / replacement hydrostatic pressure test on Class 1,2, and 3 welds. Alternative examinations are proposed. ALTERNATE EXAMINATION: Alternative examinations delineated in Code Case NA16-1 may be performed in lieu of Code required hydrostatic tests. These alternative examinations are as follows. (1) Perfonn nondestructive examinations in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 Edition of ASME Section III. (2) Perform a VT-2 visual examination of the welds in conjunction with the system leakage test using the 1992 Edition of ASME Section XI (IWA-5000) at nominal operating pressure and temperature. (3) The use of Code Case N-416-1 will be documented in the applicable owners data report (NIS-2). El-1
FNP-1-M-043 RELIEF REQUEST FNP-1 RR-47 l JUSTIFICATION FOR THE GRANTING OF RELIEF: 4 SNC has determined that hydrostatic testing post repair / replacement welds represents an undue hardship. Hardships are generally encountered with the performance of - hydrostatic testing performed in accordance with the Code. For example, since hydrostatic test pressure would be higher than nominal operating pressure, hydrostatic pressure testing frequently requires significant effort to set up and perform. The need i to use special equipment and the need for individual valve lineups can cause the testing ] to impact refueling outage schedules. 4 Piping components are designed for a number ofloadings that would be postulated to occur under the various modes of plant operation. Section XI hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure j and, therefore, does not present a significant challenge to pressure boundary conditions. Accordingly, hydrostatic pressure testing is primarily regarded as a means to enhance leakage detection during the examination of components under pressure, rather than solely as a measure to determine the structural integrity of the components. The ASME Subcommittee Working Group on pressure testing concluded that no additional benefit is gained by conducting the existing system hydrostatic tests in place of the alternate rules which require a leak test at nominal operating pressure. The cor.<clusion of the group was that hydrostatic testing does not necessarily verify structural integrity, and in fact, the slightly higher test pressures currently called for in the Code could result in operational difficulties as well as extended outages and increased costs. Industry experience has demonstrated that hydrostatic test pressures do not usually L propagate an existing flaw into a through-wall leak. This experience indicates that leaks in most cases are being found when the system is at normal operating pressure. This is largely due to the fact that hydrostatic pressure testing is infrequently 4 performed, while system leakage tests at normal operating pressures are conducted a minimum of once each refueling outage for Class I systems, and each 40-month inspection period for Class 2 and 3 systems. In addition, leaks may be identified during system walkdowns by plant operators. 4 El-2
FNP-1-M-043 RELIEF REQUEST FNP-1 RR-47 JUSTIFICATION FOR THE GRANTING OF RELIEF: (Continued) SNC has determined that the nondestructive examinations and their associated acceptance criteria provide assurance of the structuralintegrity of the weld. The proposed alternative examinations will provide reasonable assurance that unallowable flaws are not present in the subject welds. Consequently, an acceptable level of quality and safety will be achieved and public health and safety will not be endangered by allowing the proposed alternative examination in lieu of the Code requirement. 4 } l El-3
i FNP-2-M-068 RELIEF REQUEST FNP-2 EJL_2 i COMPONENT OR 2 RELIEF AREA: All ASME Class 1,2, and 3 piping and components. i REQUIREMENT FROM WIIICH RELIEFIS REQUESTED: The 1983 Edition through Summer 1983 addenda, Section XI, IWA-4400(a) requires that a system hydrostatic test be performed in accordance with IWA-5000 after a welded repair on a pressure retaining boundary. ) BASIS FOR RELIEF: Reliefis requested from performing this Code required post repair / replacement hydrostatic pressure test on Class 1, 2, and 3 welds. Alternative examinations are proposed. \\ ALTERNATE EXAMINATION: Alternative examinations delineated in Code Case N-416-1 may be performed in lieu of Code required hydrostatic tests. These alternative examinations are as follows. (1) Perform nondestructive examinations in accordance with the methods and acceptance criteria of the applicable subsection of the 1992 Edition of ASME Section III. (2) Perform a VT-2 visual examination of the welds in conjunction with the system leakage test using the 1992 Edition of ASME Section XI (IWA-5000) at nominal operating pressure and temperature. (3) The use of Code Case N-416-1 will be documented in the applicable owners data report (NIS-2). 4 i E2-1
=._ a FNP-2-M-068 ~ RELIEF REQUEST FNP-2 RR-47 JUSTIFICATION FOR THE GRANTING OF RELIEF: SNC has determined that hydrostatic testing post repair / replacement welds represents an undue hardship. Hardships are generally encountered with the performance of hydrostatic testing performed in accordance with the Code. For example, since hydrostatic test pressure would be higher than nominal operating pressure, hydrostatic pressure testing frequently requires significant effort to set up and perform. The need to use special equipment and the need for individual valve lineups can cause the testing to impact refueling outage schedules. Piping components are designed for a number ofloadings that would be postulated to ~ occur under the various modes of plant operation. Section XI hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure and, therefore, does not present a significant challenge to pressure boundary conditions. Accordingly, hydrostatic pressure testing is primarily regrrded as a means to enhance leakage detection during the examination of components under pressure, rather than solely as a measure to determine the structural integrity of the components. The ASME Subcommittee Working Group on pressure testing concluded that no q additional benefit is gained by conducting the existing system hydrostatic tests in place j of the alternate rules which require a leak test at nominal operating pressure. The conclusion of the group was that hydrostatic testing does not necessarily verify structural integrity, and in fact, the slightly higher test pressures currently called for in i the Code could result in operational difficulties as well as extended outages and increased costs. Industry experience has demonstrated that hydrostatic test pressures do not usually t propagate an existing flaw into a through-wall leak. This experience indicates that leaks in most cases are being found when the system is at normal operating pressure. This is largely due to the fact that hydrostatic pressure testing is infrequently performed, while system leakage tests at normal operating pressures are conducted a minimum of once each refueling outage for Class I systems, and each 40-month inspection period for Class 2 and 3 systems. In addition, leaks may be identified during system walkdowns by plant operators. 4 i E2-2
FNP-2-M-068 RELIEF REQUEST FNP-2 RR-47 JUSTIFICATION FOR THE GRANTING OF RELIEF: SNC has determined that the nondestructive examinations and their associated acceptance criteria provide assurance of the structural integrity of the weld. The proposed alternative examinations will provide reasonable assurance that unallowable flaws are not present in the subject welds. Consequently, an acceptable level of quality and safety will be achieved and public health and safety will not be endangered by allowing the proposed alternative examination in lieu of the Code requirement. i s E2-3
l CASE N-416-1 CASES OF ASME BOILER AND PRESSURE VESSEL CODE CASE N-416-1 Approval Date February 15,1994 i Case N-416-1 Alternative Pressure Test Requirement for Welded Repairs or Installation of Replacement Items by Welding, Class 1,2 and 3, Section XI, Division 1 Inquiry: What alternative pressure test may be performed in lieu of the hydrostatic pressure test required by paragraph IWA-4000 for welded repairs or installation of replacement items by welding? Reply: It is the opinion of the committee that in lieu of performing the hydrostatic pressure test required by paragraph IWA-4000 for welded repairs or installation of replacement items by welding, a system leakage test may be used provided the following requirements are met. (a) NDE shall be performed in accordance with the methods and acceptance criteria of the applicable Subsection af the 1992 Edition of Section III. 4 (b) Prior to or immediately upon return to service, a visual examination (VT-2) shall be performed in conjunction wi'.h a system leakage test, using the 1992 Edition of Section XI, in accordance with paragraph IWA 5000, at nominal i operating pressure and temperature. (c) Use of this Case shall be documented on an NIS-2 Form. 3 If the previous version of this case were used to defer a Class 2 hydrostatic test, the deferred test may be eliminated when the requirements of this revision are met. E3-1 -}}