ML042100039
| ML042100039 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/23/2004 |
| From: | Nunn D Southern California Edison Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BL-04-001 | |
| Download: ML042100039 (12) | |
Text
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SOUTHERN CALIFORNIA n EDISON C An EDISON INTERNATIONALS Company Dwight E. Nunn Vice President July 23, 2004 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C., 20555-0001
Subject:
Docket Nos. 50-361 and 50-362 60-day Response to NRC Bulletin 2004-01: Inspection Of Alloy 8211821600 Materials Used In The Fabrication Of Pressurizer Penetrations And Steam Space Piping Connections At Pressurized-Water Reactors San Onofre Nuclear Generating Station, Units 2 and 3
Reference:
NRC Bulletin 2004-01: Inspection Of Alloy 82/182/600 Materials Used In The Fabrication Of Pressurizer Penetrations And Steam Space Piping Connections At Pressurized-Water Reactors, Issued May 28, 2004
Dear Sir or Madam:
This letter provides the Southem California Edison Company (SCE) 60-day response to the referenced NRC Bulletin 2004-01, in accordance with 10 CFR 50.54(f). The information requested in NRC Bulletin 2004-01 is provided as an enclosure with this letter.
If you have any questions or would like additional information concerning this subject, please call Mr. Jack Rainsberry (949) 368-7420.
Sincerely
Enclosure:
cc:
B. S. Mallett, Regional Administrator, NRC Region IV B. M. Pham, NRC Project Manager, San Onofre Units 2 and 3 C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 and 3 P.O. Box 128 San Clemente, CA 92674-0128 949-368-1480 Fax 949-368-1490
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State of California County of San Diego Sypscribed and sworn to (or affirmed) before me thisq day of by Notary Public As sm 0*0
SCE Response to NRC Bulletin 2004-01 Requested Information:
(a) A description of the pressurizer penetrations and steam space piping connections at your plant. At a minimum, this description should include materials of construction (e.g., stainless steel piping and/or weld metal, Alloy 600 piping/sleeves, Alloy 82/182 weld metal or buttering, etc.), joint design (e.g.,
partial penetration welds, full penetration welds, bolted connections, etc.), and, in the case of welded joints, whether or not the weld was stress-relieved prior to being put into service. Additional information relevant with respect to determining the susceptibility of your plant's pressurizer penetrations and steam space piping connections to PWSCC should also be included.
Southern California Edison (SCE) Response:
The following table lists each type of pressurizer penetration and steam space piping connection for the pressurizers at the San Onofre Nuclear Generating Station (SONGS) Units 2 and 3, excluding the surge line nozzle.
Description of SONGS 213 Pressurizer Penetrations and Steam Space Piping Connections Item Quanty Joint Materials Joint Type PWHT Unit 2 Unit 3 See Note 1 Pressurizer 30 29 Bot. Hd. Clad: Alloy 82 Partial Penetration No Heater Sleeves J-Weld: Alloy 82/182 J-groove on Bottom See Note 2 Sleeve: Alloy 600 Head inside surface Repaired 0
1 Vessel: Low Alloy Steel Temper bead Pad No Pressurizer Pad: Alloy 52 wI Partial Heater Sleeve J-Weld: Alloy 52 Penetration J-Sleeve: Alloy 690 groove on Bottom Head exterior surface Pressurizer 30 28 Sleeve: Alloy 600 Fillet Weld, sleeve No Heaters Weld:
Alloy 82 to heater sheath Heater: Stainless Steel Pressurizer 0
1 Sleeve: Alloy 690 Fillet Weld, sleeve No Heater @
Weld:
Alloy 52 to heater Repaired Heater: Stainless Steel Sleeve Capped Heater 0
1 Sleeve: Alloy 600 Fillet Weld, sleeve No Sleeve Weld:
Alloy 52 to cap Cap:
Alloy 690 Page 1 of 7
SCE Response to NRC Bulletin 2004-01 Item Quantity Joint Materials Joint Type PWHT Unit 2 Unit3 See Note 1 Steam Space 4
4 Vessel: Low Alloy Steel Partial Penetration Butter: Yes Instrument Butter: Alloy 82/182 J-groove on Upper J-weld: No Nozzles to J-Weld: Alloy 52 Head inside surface See Note 3 Pressurizer Nozzle: Alloy 690 Replaced 0
1 Vessel: Low Alloy Steel Partial Penetration Butter: Yes Temperature Butter: Alloy 82/182 J-groove on Side J-weld: No Nozzle Weld:
Alloy 82 Shell inside surface See Note 3 Nozzle: Alloy 600 Repaired 1
0 Vessel: Low Alloy Steel Temper bead Pad No Temperature Pad:
Alloy 52 w/ Partial Nozzle J-Weld: Alloy 52 Penetration J-Nozzle: Alloy 690 groove on Side Shell exterior surface Lower Level 2
2 Vessel: Low Alloy Steel Partial Penetration Butter: Yes Nozzles Butter: Alloy 182 J-groove on Bottom J-weld: No J-Weld: Alloy 821182 Head inside surface See Note 3 Nozzle: Alloy 600 Safety Valve (2) 3 3
Nozzle: Low Alloy Steel Full Penetration Butt Butter: Yes and Spare (1)
Butter: Alloy 182 Weld Butt-Weld:
Nozzles Safe End: Stainless Steel No Butt Weld: Alloy 82 &182 See Note 4 Spray Nozzle I
I Nozzle: Low Alloy Steel Full Penetration Butt Butter: Yes Butter: Alloy 182 Weld Butt-Weld:
Safe End: Stainless Steel No Butt Weld: Alloy 82 &182 See Note 4 Note 1: PWHT is an acronym for 'post weld heat treatment and is the process that results in components being stress-relieved prior to being put in service.
Note 2: The internal surface of the pressurizer bottom head was clad using the submerged arc welding (SAW) process with 7/16" minimum deposit thickness of Alloy 82. This clad deposit was post weld heat treated and examined by ultrasonic testing (UT) and penetrant testing (PT). The heater sleeve j-growve weld preparation and weld were made within the clad volume. The cladding deposit serves as a corrosion resistant overlay and in the heater sleeve j-weld areas as a butter deposit. No additional PWHT was performed after completion of the j-welds.
Note 3: The small bore temperature/instrument nozzle j-groove weld preparations were machined into the vessel headishell after the Internal cladding was applied. An Alloy 182 butter deposit was applied over the exposed low alloy steel material and tied into the cladding at the surface. PWHT was then performed on the butter deposit concurrently with PWHT of the cladding. The butter deposit was PT examined before installation of the nozzle. The nozzle was then installed and j-groove welded using Alloy 182. A progressive PT examination was performed on the nozzlej-weld. No additional PWHT was perforned after completion of thej-weld.
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SCE Response to NRC Bulletin 2004-01 Note 4: The low alloy large bore nozzles are welded to the vessel with a low alloy weld material and are internally dad which isolates the vessel, nozzle and weld from the borated water environment. The ends of the low alloy nozzles are buttered with Alloy 182 weld deposit. PWHT was performed on the butter deposit followed by radiographic testing (RT) and PT examinations.
The ends of the stainless steel safe ends that join to the safety valve nozzle ends have an Alloy 182 butter deposit applied and were examined by RT and PT. No PWHT was performed on the safe end butter deposit The ends of the stainless steel safe ends that join to the spray nozzles do not have a butter deposit The safe ends and nozzles were then fit-up and welded together with a full penetration butt weld. The butt weld was made using an Alloy 82 root pass and Alloy 182 fill passes. No additional PWHT was performed after completion of the butt weld. The completed butt weld and butter deposits were then examined by RT and PT. A UT exam was then performed to establish the baseline for subsequent ASME Xl Inservice Inspections.
The pressurizer heaters were originally attached to the heater sleeves with an Alloy 82 fillet weld. Replacement heaters may be welded in place with either Alloy 82 or Alloy 52. At Unit 3, one heater sleeve has been repaired with an Alloy 690 half sleeve and one Alloy 600 heater sleeve has been capped with an Alloy 690 cap. The fillet welds on these two heater sleeves are Alloy 52.
The instrument nozzles include four steam space nozzles installed in the upper head, one nozzle in the side shell, and two nozzles in the bottom head at each unit. The four nozzles in the upper head provide pressure taps to monitor pressurizer pressure and two of them double as upper level taps. All four of the steam space instrument nozzles at each unit have been replaced with full length Alloy 690 nozzles. The two nozzles in the bottom head are the lower level taps and the side shell nozzle contains a thermowell for pressurizer temperature measurement. The side shell nozzle at Unit 2 has been repaired with an Alloy 690 half nozzle. As a proactive measure, mechanical nozzle seal assemblies (MNSA) were installed on the instrument nozzles on the bottom head of at both Unit 2 and Unit 3 and on the side shell nozzle at Unit 3.
There are three (3) six inch piping connections to the pressurizer steam space in the upper head. Two of these are used for safety valves and one is a spare connection. The spray line is connected to a four inch nozzle located in the top center of the upper head.
SONGS Unit 2 and Unit 3 pressurizers have each accumulated approximately 20 years of service at pressurizer operating conditions. There are no other known factors that would significantly affect primary water stress corrosion cracking (PWSCC) susceptibility of the pressurizer penetrations and attached piping.
Page 3 of 7
SCE Response to NRC Bulletin 2004-01 Requested Information:
(b) A description of the inspection program for Alloy 82/1821600 pressurizer penetrations and steam space piping connections that has been implemented at your plant The description should include when the inspections were performed; the areas, penetrations and steam space piping connections inspected; the extent (percentage) of coverage achieved for each location which was inspected; the inspection methods used; the process used to resolve any inspection findings; the quality of the documentation of the inspections (e.g., written report, video record, photographs); and, the basis for concluding that your plant satisfies applicable regulatory requirements related to the integrity of pressurizer penetrations and steam space piping connections. If leaking pressurizer penetrations or steam space piping connections were found, indicate what follow-ups NDE [non-destructive examination] was performed to characterize flaws in the leaking penetrations.
SCE Response:
A description of the SONGS inspection program is provided in Appendix A.
Leakage has been identified by visual examination at six pressurizer instrument penetrations. Eight follow up Liquid Penetrant examinations of the J-groove attachment welds for steam space instrument penetrations have been performed and five rejectable indications were identified. No circumferential cracking was detected.
One heater sleeve was examined with eddy current to determine if cracking had initiated as a result of a swollen heater within the sleeve. A short axial crack like indication was identified and the penetration was replaced. No other pressurizer penetrations have been non-destructively examined to characterize the flaws.
For a discussion of the basis for concluding that SONGS Units 2 and 3 will satisfy applicable regulatory requirements related to the structural and leakage integrity of pressurizer penetrations and steam space piping connections, see the response to Question (d) below.
Requested Information:
(c) A description of the Alloy 82/182/600 pressurizer penetration and steam space piping connection inspection program that will be implemented at your plant during the next and subsequent refueling outages. The description should include the areas, penetrations and steam space piping connections to be inspected; the extent (percentage) of coverage to be achieved for each location; Page 4 of 7
SCE Response to NRC Bulletin 2004-01 inspection methods to be used; qualification standards for the inspection methods and personnel; the process used to resolve any inspection indications; the inspection documentation to be generated; and the basis for concluding that your plant will satisfy applicable regulatory requirements related to the structural and leakage integrity of pressurizer penetrations and steam space piping connections. If leaking pressurizer penetrations or steam space piping connections are found, indicate what follow-up NDE will be performed to characterize flaws in the leaking penetrations. Provide your plans for expansion of the scope of NDE to be performed if circumferential flaws are found in any portion of the leaking pressurizer penetrations or steam space piping connections.
SCE Response:
Appendix A includes a description of the future inspection schedule for the Alloy 82/182/600 pressurizer penetration and steam space piping connection inspection program.
For a discussion of the basis for concluding that SONGS Units 2 and 3 will satisfy applicable regulatory requirements related to the structural and leakage integrity of pressurizer penetrations and steam space piping connections, see the response to Question (d) below.
Requested Information:
(d) In light of the information discussed in this bulletin and your understanding of the relevance of recent industry operating experience to your facility, explain why the inspection program identified in your response to item (1)(c) above is adequate for the purpose of maintaining the integrity of your facility's RCPB
[Reactor Coolant Pressure Boundary] and for meeting all applicable regulatory requirements which pertain to your facility.
SCE Response:
The following Regulatory Requirements establish criteria applicable to the inspection program outlined in our response to item 1 (c), and contribute to ensuring that the integrity of the Reactor Coolant Pressure Boundary (RCPB) is maintained:
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SCE Response to NRC Bulletin 2004-01 General Design Criteria GDC 14 Reactor Coolant Pressure Boundary GDC 31 Fracture Prevention of Reactor Coolant Pressure Boundary GDC 32 Inspection of Reactor Coolant Pressure Boundary Code of Federal Regulations 1 OCFR50.55a Codes and Standards 10CFR50 Appendix B Criterion V, Instructions, Procedures and Drawings I OCFR50 Appendix B Criterion IX, Control of Special Processes IOCFR50 Appendix B Criterion XVI, Corrective Action SONGS 2 and 3 Technical Specifications Compliance with the General Design Criteria specified above was achieved by design, fabrication, construction, and Inservice Inspection of the Reactor Coolant System in accordance with 10CFR50.55(a) and the ASME Code. Inservice Inspection is performed to ensure continued compliance with these requirements under the SONGS Inservice Inspection Program and is consistent with ASME Section Xi requirements. The SONGS Inservice Inspection Program is implemented under the SONGS Quality Assurance Program. That program ensures that 10CFR50 Appendix B requirements are also met.
SCE continuously monitors industry events, including the information discussed in NRC Bulletin 2004-01, and has expanded the RCPB inspections to include inspections that are not required under the existing ASME Section Xl program or other regulatory requirements. These supplemental inspections (Alloy 600 Inspection procedure and Boric Acid inspection procedure) are implemented under the SONGS Appendix B Quality Assurance Program. The supplemental inspections include directed inspection of RCPB locations where PWSCC susceptibility may not have been fully envisioned by the ASME Code inspection requirements. These inspections include Bare Metal Visual examination of pressurizer external surfaces associated with Alloy 82/182 welds and Alloy 600 components every refueling outage. These inspections are capable of detecting minimal amounts of through wall leakage. It is SCE's position that these inspections are adequate to ensure that integrity of RCPB is maintained and the potential for challenging plant safety systems is minimized. This assessment is supported by technical evaluations performed by EPRI and the Westinghouse Owners group, and it is consistent with NRC expectations set forth in Bulletin 2004-01.
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SCE Response to NRC Bulletin 2004-01 Nomenclature:
For the purpose of this response, SCE considers the material description in the left column to be equivalent to the corresponding material description in the right column:
Welding Filler Materials Alloy 82 ASME II, Part C, SFA 5.14, AWS Class ERNiCr-3 Alloy 182 ASME II, Part C, SFA 5.11, AWS Class ENiCrFe-3 Alloy 52 ASME II, Part C, SFA 5.14, AWS Class ERNiCrFe-7 Alloy 152 ASME II, Part C, SFA 5.11, AWS Class ENiCrFe-7 Base Materials Alloy 600 ASME II, Part B, SB-166, UNS No. N06600 or ASME II, Part B, SB-167, UNS No. N06600 Alloy 690 ASME II, Part B, SB-166, UNS No. N06690 or ASME II, Part B, SB-167, UNS No. N06690 Page 7 of 7
Appendix A SONGS Units 2 and 3 Inspection Program for 8211821600 Pressurizer Penetrations and Steam Space Pipe Connections Documentation Penetration Inspection Method Tknes of In-service Inspections Inspection Area Qualification Process for method Type and Coverage resolving indications Previously Implemented Next and Future Inspections Inspections See Note I Unit-2 Each inspection In accordance with 10 CFR 50.55a Written report ASME Section XI ISI Cycle-6 refueling See Note 2 100%
ASME Section Xl In accordance with UT Cycle-12 refueling of weld volume requirements in and ASME Section Xl effect during requirements in effect Unit-3 inspection ASME Code during Inspection Cycle-6 refueling Section XI Pressurizer Unt-2 Each Inspection 10 CFR 50.55a Written report safety ASME Section XI ISI None See Note 2 100%
In accordance with In accordance with valve UT of weld volume Code and PDI and ASME Section Xl header (PDI)
Unit-3 requirements requirements in effect Cycle-12 refueling ASME Code during inspection
_Section XI
-and-Unit-2 Each Inspection In accordance with 10 CFR 50.55a Written report ASME Section Xl ISI Cycle-6 refueling See Note 2 100%
ASME Section XI In accordance with Pressurizer PT Cycle-12 refueling of weld surface requirements in and ASME Section Xl Spray Une effect during requirements In effect to Unit-3 inspection ASME Code during inspection pressurizer Cycle-6 refueling Section XI CycIe-12 refueling Each Refueling 100% per ASME In accordance with 10 CFR 50.55a Written report ASME Section Xl ISI Each Refueling outage outage Section XI Code ASME Section XI In accordance with VT-2 requirements in and ASME Section XI effect during requirements In effect Inspection ASME Code during inspection Section Xl Engineering Unit-2 UnIt-2 Each inspection 10 CFR 50.55a Bare Metal Visual 3/04 Each Refueling 100%
SCE Qualification (BMV) outage of weld surface Standard and Engineering Inspection Unit-3 Procedure none Unit-3 ASME Code Each Refueling Section Xl
~~~outage_
Page 1 of 3
Appendix A SONGS Units 2 and 3 Inspection Program for 82/1821600 Pressurizer Penetrations and Steam Space Pipe Connections Penetration Inspection Method Times of In-service Inspections Inspection Area Qualification Process for Documentation Type and Coverage resolving Method Indications Previously Implemented Nxt and Future Inspections Inspections See Note I Unit-2 10 CFR 50.55a Liquid Penetrant none none 100% of J-9roove ANST Level II NDE Inspection Report (steam space weld surface and penetrations)
Unl-3 (vessel ID) 1992 none ASME Code Instrument 1995 Section Xi Nozzles In Pressurizer In accordance 10 CFR 50.55a Written report ASME Section Xl ISI Each Refueling outage Each Refueling 100% per ASME with In accordance with VT-2 outage Section Xl Code ASME Section Xi and ASME Section XI requirements In requirements in effect effect during ASME Code during inspection Inspection Section Xi Engineering Unk-2 MNSA Inspection 100% of nozzles, 10 CFR 50.55a Bare Metal Visual Every refueling since Each Refueling 380 degrees of SCE Qualification (BMV) 1993 outage circumference Standard and Engineering Inspection
-or-Unit-3 Including sealing Procedure Engineering MNSA Every refueling since (all Alloy 600 surface or crevice ASME Code Inspection 1993 penetrations now as applicable.
Section Xl as applicable have MNSA)
Page 2 of 3
Appendix A SONGS Units 2 and 3 Inspection Program for 8211821600 Pressurizer Penetrations and Steam Space Pipe Connections Penetration Inspection Method Times of In-service Inspections Inspection Area Qualification Process for Documentation Type and Coverage resoving Method indications Previously Implemented Next and Future Inspections Inspections (1)
Each Refueling 100% perASME In accordance 10CFR 50.55a Written report ASME Section XI ISI Each Refueling outage outage Section XI Code with In accordance with Pressurizer VT-2 ASME Section XI and ASME Section XI Heater Sleeves requirements In requirements In effect to Pressurizer effect during ASME Code during Inspection Inspection Section XI and Heater Sleeves Engineering Unit-2 100% of external 10 CFR 50.55a to Heaters Bare Metal Visual Every refueling since Each Refueling penetration, SCE Qualification (BMV) 1993 outage 360 degrees of Standard and Engineering Inspection circumference Procedure Unit-3 (including sleeve ASME Code Every refueling since crevice and heater Section XI 1993 element weld)
(1) If any indications of leakage are found in either an Alloy 600 penetration or a pressurizer piping connection weld, then follow-up nondestructive examination (NDE) will be performed to characterize the orientation of the crack prior to performing a repair or replacement activity other than the use of a MNSA. (SCE has requested relief to use MNSA 2 for pressurizer heater sleeves without first characterizing the crack orientation. If a MNSA 2 is installed, the characterization of crack orientation will be performed in accordance with the requirements of the relief request Safety Evaluation.) In addition, if circumferential cracking is found in any leaking pressurizer penetration or steam space piping connection, SCE will develop plans for expanded Inspection scope and discuss those plans with the NRC prior to returning the affected unit to service.
(2) In Accordance with I OCFR50.55a(a)(3)(i), SONGS has submitted Relief Request ISI-3-1 for SONGS Units 2 and 3, Risk-lnformed Inservice Selection and Examination for Class-1 piping welds Docket Nos. 50-361 and 50-362, dated July 2, 2003. Currently NRC is reviewing the relief request. After NRC approval SONGS will perform the examinations in accordance with the requirements of the relief request Safety Evaluation.
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