L-07-022, Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds
| ML070330595 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/31/2007 |
| From: | Lash J FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-07-022 | |
| Download: ML070330595 (12) | |
Text
FENOC FirstEnergy Nuclear Operating Company James H. Lash 724-682-5234 Site Vice President Fax: 724-643-8069 January 31, 2007 L-07-022 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Beaver Valley Power Station, Unit No. 1 and No. 2 BV-1 Docket No. 50-334, License No. DPR-66 BV-2 Docket No. 50-412, License No. NPF-73 Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds In August 2005, the Electric Power Research Institute (EPRI) issued the Materials Reliability Program: Primary System Piping Butt Weld Inspection and Evaluation Guidelines, MRP-139. This guideline established an objective of completing, by December 31, 2007, baseline volumetric exams of all Alloy 600/82/182 dissimilar metal butt welds greater than or equal to 4" nominal pipe size (NPS) that normally operate at pressurizer temperatures.
During the Refueling Outage (2R12) in the fall of 2006, FENOC completed full mitigation of potential defects in the subject BVPS Unit No. 2 welds through application of full structural weld overlays to the pressurizer spray nozzle, relief (PORV) nozzle, three safety nozzles, and surge nozzle. The final weld overlay ultrasonic examinations were completed on November 6, 2006. FENOC provided the results of these examinations for BVPS Unit No. 2 via letter L-06-163 dated November 20, 2006 (Reference 1).
In the fall 2007 outage (1R18), FENOC will perform mitigation activities and conduct the required inspections for the BVPS Unit No. 1 pressurizer Alloy 600/82/182 nozzle butt welds. Additionally, to support the mitigation activities planned at BVPS Unit No. 1, FENOC is developing a request for Nuclear Regulatory Commission approval of a proposed weld overlay repair alternative, in accordance with the requirements of 10 CFR 50.55a. Details concerning the inspections and mitigation activities for both BVPS Unit Nos. 1 and 2 are provided in Attachment 1.
While no pre-mitigation Performance Demonstration Initiative (PDI) qualified ultrasonic examinations have been completed on the Unit No. 1 and 2 pressurizer nozzle locations due to configuration limitations, the results of non-PDI non-destructive examinations are provided in Attachment 2. Site procedures will be revised to reflect that future
Beaver Valley Power Station, Unit Nos. 1 & 2 Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds L-07-022 Page 2 inspections of pressurizer butt welds at BVPS Unit Nos. 1 and 2 will be performed in accordance with industry guidance (MRP-139), and that the results will be reported to the NRC within 60 days of startup from the outage during which they were performed.
FENOC enhanced the BVPS reactor coolant system (RCS) integrated leakage monitoring program in 2004. The program exceeds acceptance criteria required by the BVPS technical specifications. Leakage data is captured on a daily basis for trend analysis, and measurements are periodically validated with other plant data. The FENOC and BVPS management teams have reinforced strong ownership and maintained fleet visibility of this program by including leakage monitoring discussions daily in fleet status calls, as well as monthly in routine management meeting presentations. Through improved program requirements and ownership, reactor coolant system pressure boundary leakage is being actively monitored. Additional details relevant to the RCS integrated leakage monitoring program are contained in Attachment 3.
Regulatory commitments associated with this letter are listed in Attachment 4.
If there are any questions or if additional information is required, please contact Mr. Gregory H. Halnon, Director - FENOC Fleet Regulatory Affairs, at (330) 315-7500.
.**ames H. Lash Attachments:
- 1.
Inspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds
- 2.
Results of Previous Inspections of Alloy 600/82/182 Pressurizer Butt Welds
- 3.
RCS Leakage Monitoring for BVPS Unit Nos. 1 & 2
- 4.
Commitment List
References:
- 1. Pressurizer Weld Overlay Examination Report (BVPS-2), FENOC letter L 163 dated November 20, 2006
Beaver Valley Power Station, Unit Nos. 1 & 2 Inspection and Mitigation of Alloy 600/82/182 Pressurizer Butt Welds L-07-022 Page 3 cc:
Ms. N. Morgan, NRR Senior Project Manager Mr. P. C. Cataldo, NRC Senior Resident Inspector Mr. S. J. Collins, NRC Region I Administrator Mr. D. A. Allard, Director BRP/DEP Mr. L. E. Ryan (BRP/DEP)
Mr. James H. Riley (NEI)
Mr. Marvin S. Fertel (NEI)
Mr. Terrence L. Chan, NRR Mr. Ted J. Sullivan, NRR of L-07-022 Inspection and Mitigation Summary for Alloy 600/82/182 Pressurizer Butt Welds Beaver Valley Unit 1 MRP-139 Volumetric Inspection Mitigation to Requirement Met or to be Met be Completed Function /
Susceptible Outage Start Date Outage Comments Material Designation Description Designation (MM/YYYY)
Designation 4" Spray nozzle-to-Alloy 82/182, 1R18 09/2007 1R18 Full structural weld overlay to be safe end weld Ni-Cr-Fe Weld Metal, applied during 1R18. Examination (Weld #
F-Number 43 requirement will be met post-RC-72-1-E-01) overlay.
14" Surge nozzle No A600/82/182 N/A N/A None Stainless steel welds and safe end -
non-susceptible material 6" Safety A nozzle-Alloy 82/182, 1R18 09/2007 1R18 Full structural weld overlay to be to-safe end weld Ni-Cr-Fe Weld Metal, applied during 1 R18. Examination (Weld #
F-Number 43 requirement will be met post-RC-97-I-E-01) overlay.
6" Safety B nozzle-Alloy 82/182, 1R18 09/2007 1R18 Full structural weld overlay to be to-safe end weld Ni-Cr-Fe Weld Metal, applied during 1R18. Examination (Weld #
F-Number 43 requirement will be met post-RC-98-1-E-02) overlay.
6" Safety C nozzle-Alloy 82/182, 1R18 09/2007 1R18 Full structural weld overlay to be to-safe end weld Ni-Cr-Fe Weld Metal, applied during 1R18. Examination (Weld #
F-Number 43 requirement will be met post-RC-99-1-E-03) overlay.
6" Relief nozzle-to-Alloy 82/182, 1R18 09/2007 1R18 Full structural weld overlay to be safe end weld Ni-Cr-Fe Weld Metal, applied during 1 R18. Examination (Weld #
F-Number 43 requirement will be met post-RC-104-1-E-01) overlay.
of L-07-022 Page 2 of 2 Beaver Valley Unit 2 Nozzle MRP-139 Volumetric Inspection Mitigation Requirement Met or to be Met Completed Function /
Susceptible Outage Start Date Outage Comments Designtion'Material Designation' Description Designation (MM/YYYY)
Designation 4" Spray nozzle-to-Alloy 82/182, 2R12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-202Z) transmitted via letter L-06-163.
14" Surge nozzle-to-Alloy 82/182, 2R 12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-84Z) transmitted via letter L-06-163.
6" Safety A nozzle-to-Alloy 82/182, 2R12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-103C) transmitted via letter L-06-163.
6" Safety B nozzle-to-Alloy 82/182, 2R12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-102B) transmitted via letter L-06-163.
6" Safety C nozzle-to-Alloy 82/182, 2R12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-101A) transmitted via letter L-06-163.
6" Relief nozzle-to-Alloy 82/182, 2R12 10/2006 2R12 Full structural weld overlay applied safe end weld Ni-Cr-Fe Weld Metal, during 2R12. Examination (Weld #
F-Number 43 requirement met post-overlay - results 2RCS*PRE21-107Z) transmitted via letter L-06-163.
of L-07-022 Results of Previous Inspections of Alloy 600/82/182 Pressurizer Butt Welds Beaver Valley Unit 1 Weld # RC-72-1-E 4" Spray Nozzle-to-Safe End Weld RC-72-1-E-01 joins a SA-216, Gr. WCC stainless steel clad carbon steel nozzle to a SA-182 Type 316 stainless steel safe end using Alloy 82/182 weld material.
Weld RC-72-I-E-01 was ultrasonically examined in 1997 using refracted longitudinal search units in accordance with the BVPS ISI Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of RC-72-1-E-01 performed during the past two refueling outages (Fall 2004, Spring 2006) identified no indications of leakage.
Weld # RC-97-1-E-O1 - 6" Safety "A" Nozzle-to-Safe End Weld RC-97-1-E-01 joins a SA-216, Gr. WCC stainless steel clad carbon steel nozzle to a SA-182 Type 316 stainless steel safe end using Alloy 82/182 weld material.
Weld RC-97-l-E-01 was ultrasonically examined in 1997 using refracted longitudinal search units in accordance with the BVPS ISI Plan. Examination coverage was limited to 93% due to the weld configuration and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of RC-97-1-E-01 performed during the past two refueling outages (Fall 2004, Spring 2006) identified no indications of leakage.
Weld # RC-98-1-E 6" Safety "B" Nozzle-to-Safe End Weld RC-98-I-E-02 joins a SA-216, Gr. WCC stainless steel clad carbon steel nozzle to a SA-182 Type 316 stainless steel safe end using Alloy 82/182 weld material.
Weld RC-98-l-E-02 was ultrasonically examined in 1997 using refracted longitudinal search units in accordance with the BVPS ISI Plan. Examination coverage was limited to 64% due to the weld configuration and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of RC-98-1-E-02 performed during the past two refueling outages (Fall 2004, Spring 2006) identified no indications of leakage.
Weld # RC-99-1-E 6" Safety "C" Nozzle-to-Safe End Weld RC-99-1-E-03 joins a SA-216, Gr. WCC stainless steel clad carbon steel nozzle to a SA-182 Type 316 stainless steel safe end using Alloy 82/182 weld material.
of L-07-022 Page 2 of 4 Weld RC-99-1-E-03 was ultrasonically examined in 1997 using refracted longitudinal search units in accordance with the BVPS ISI Plan. Examination coverage was limited to 84% due to the weld configuration and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of RC-99-1-E-03 performed during the past two refueling outages (Fall 2004, Spring 2006) identified no indications of leakage.
Weld # RC-104-1-E-O1 - 6"Relief Nozzle-to-Safe End Weld RC-104-1-E-01 joins a SA-216, Gr. WCC stainless steel clad carbon steel nozzle to a SA-182 Type 316 stainless steel safe end using Alloy 82/182 weld material.
Weld RC-104-1-E-01 was ultrasonically examined in 1997 using refracted longitudinal search units in accordance with the BVPS IS Plan. Examination coverage was limited to 72% due to the weld configuration. An indication characterized as "metallurgical in origin" was recorded with the 600 R/L search unit. The indication was 63% DAC (Distance Amplitude Correction), 1" long, with sensitivity established using a 10% ID notch. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of RC-104-1-E-01 performed during the past two refueling outages (Fall 2004, Spring 2006) identified no indications of leakage.
Beaver Valley Unit 2 Weld # 2RCS*PRE21-202Z - 4"Spray Nozzle-to-Safe End Weld 2RCS*PRE21-202Z joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
Weld 2RCS*PRE21-202Z was ultrasonically examined in 1999 using refracted longitudinal search units in accordance with the BVPS IS1 Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of 2RCS*PRE21-202Z performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2RI 2), weld 2RCS*PRE21-202Z was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
Weld # 2RCS*PRE21-84Z - 14"Surge Nozzle-to-Safe End Weld 2RCS*PRE21-84Z joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
of L-07-022 Page 3 of 4 Weld 2RCS*PRE21-84Z was ultrasonically examined in 1999 using refracted longitudinal search units in accordance with the BVPS ISI Plan. Examination coverage was limited to 92% due to the weld configuration and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of 2RCS*PRE21-84Z performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2R12), weld 2RCS*PRE21-84Z was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
Weld # 2RCS*PRE21-103C - 6"Safety "A " Nozzle-to-Safe End Weld 2RCS*PRE21-103C joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
Weld 2RCS*PRE21-103C was ultrasonically examined in 1996 using refracted longitudinal search units in accordance with the BVPS ISI Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of2RCS*PRE21-103C performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2R12), weld 2RCS*PRE21-103C was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
Weld # 2RCS*PRE21-102B - 6"Safety "B" Nozzle-to-Safe End Weld 2RCS*PRE21-102B joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
Weld 2RCS*PRE21-102B was ultrasonically examined in 1996 using refracted longitudinal search units in accordance with the BVPS ISI Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of2RCS*PRE21-102B performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2R12), weld 2RCS*PRE21-102B was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of of L-07-022 Page 4 of 4 the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
Weld # 2RCS*PRE21-101A - 6"Safety "C" Nozzle-to-Safe End Weld 2RCS*PRE21-101A joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
Weld 2RCS*PRE21-101A was ultrasonically examined in 1996 using refracted longitudinal search units in accordance with the BVPS ISI Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of2RCS*PRE21-101A performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2R12), weld 2RCS*PRE21-101A was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
Weld # 2RCS*PRE21-107Z - 6"Relief Nozzle-to-Safe End Weld 2RCS*PRE21-107Z joins a SA-508, Cl. 2A stainless steel clad low alloy steel nozzle to a SA-182 Type 316L stainless steel safe end using Alloy 82/182 weld material.
Weld 2RCS*PRE21-107Z was ultrasonically examined in 1996 using refracted longitudinal search units in accordance with the BVPS ISI Plan. 100% coverage was achieved and no recordable indications were identified. The techniques employed were not qualified to the Performance Demonstration Initiative (PDI) protocol, which was not in effect for dissimilar metal welds at that time.
In addition, bare metal visual examinations of 2RCS*PRE21-107Z performed during the past two refueling outages (Spring 2005, Fall 2006) identified no indications of leakage.
During the Fall 2006 refueling outage (2R12), weld 2RCS*PRE21-107Z was mitigated utilizing a full structural weld overlay of Alloy 52 weld material. Following application of the overlay, the outer 25% of the Alloy 82/182 weld was ultrasonically examined using PDI qualified procedures, with no indications identified.
of L-07-022 RCS Leakage Monitoring for BVPS Unit Nos. 1 & 2 Multiple inputs are used to evaluate RCS leakage at the BVPS, including RCS inventory balance, containment normal sump level, containment normal sump flow monitoring and containment radiation monitors. These inputs are utilized to establish responses for unidentified step changes in leakage as low as 0.08 gallons per minute and rates of change as low as 0.05 gallons per minute per month. Site procedures define the action level and appropriate response based on the observed leakage criteria. The action levels are defined in the following table followed by the appropriate responses.
Sustained Step Changes in Leak Rate of Change of Leakrate2 Rates' UNIDENTIFIED or Action Level UNIDENTIFIED IDENTIFIED Normal
< 0.08 gpm
< 0.05 gpm/month Operation I
> 0.08 - 0.10 gpm
> 0.05 - 0.07 gpm/month II
> 0.10 - 0.30 gpm
> 0.07 - 0.12 gpm/month III
> 0.30 gpm
> 0.12 gpm/month
- 1. Step change that exceeds the average of the previous three performances and is sustained for three consecutive performances (frequency of performance is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />).
- 2. Calculated over at least three consecutive performances.
Normal Operation Conduct scheduled area inspections.
Action Level I This action level contains steps that will provide an increased focus on parameters and indications that would help to characterize the increase in unidentified leakage. In addition to elevating the visibility of this information, inspections of systems, structures, and components are performed. Also, review of operational data, radiation surveys and data from key systems is initiated. If any leakage detection instrumentation is out of service, repairs are expedited. Consideration is given, based on the information gathered, as to whether additional monitoring and leak detection instrumentation trend analysis is warranted.
of L-07-022 Page 2 of 2 Action Level II In addition to repeating the steps of Action Level I, an extended leak rate calculation is completed, area inspections are expedited, containment airborne activity monitor filters are checked for traces of boron, and an item is added to the forced outage list to perform an inspection of the RCS for leakage. A plant shutdown within 90 days is highly recommended if in this Action Level.
Action Level III In addition to performing the actions of Action Levels I and 11, a shutdown for a containment inspection for RCS leakage is performed within 30 days. The shutdown would be a Mode 3 shutdown or below, depending on the plant conditions. If it is determined to be pressure boundary leakage, whether located at an Alloy 600 dissimilar metal weld or not, Technical Specification requirements for Pressure Boundary Leakage will require a shutdown to Mode 5.
Prior to February 28, 2007, FENOC will establish appropriate administrative controls to ensure that if BVPS Unit No. 1 shuts down due to unidentified primary system leakage and the source of the leakage cannot be confirmed, a bare metal visual examination of Alloy 600/82/182 butt weld locations on the pressurizer will be performed. The administrative controls will be required until completion of the scheduled mitigation activities for the BVPS Unit No. 1 pressurizer Alloy 600/82/182 nozzle butt welds (1 RI 8).
There is significant discussion at the Pressurized Water Reactor Owner's Group (PWROG) about leakage monitoring program changes. The PWROG is developing a uniform approach that achieves desired results without potential unintended consequences. FENOC intends to evaluate the uniform leakage monitoring program to determine any changes that should be made to the BVPS leakage monitoring program.
of L-07-022 Commitment List The following list identifies those actions committed to by FirstEnergy Nuclear Operating Company (FENOC) for Beaver Valley Power Station (BVPS) Unit Nos. I and 2 in this document. Any other actions discussed in the submittal represent intended or planned actions by FENOC. They are described only as information and are not regulatory commitments. Please notify Mr. Gregory H. Halnon, Director - FENOC Fleet Regulatory Affairs, at (330) 315-7500 of any questions regarding this document or associated regulatory commitments.
Commitments Due Date
- 1. FENOC will perform mitigation activities and conduct the required inspections for the BVPS Unit No. I pressurizer Alloy 600/82/182 nozzle butt welds.
- 2. Site procedures will be revised to reflect that future inspections of pressurizer butt welds at BVPS Unit Nos. 1 and 2 will be performed in accordance with industry guidance (MRP-139), and that the results will be reported to the NRC within 60 days of startup from the outage during which they were performed.
- 3. FENOC will establish appropriate administrative controls to ensure that if BVPS Unit No. I shuts down due to unidentified primary system leakage and the source of the leakage cannot be confirmed, a bare metal visual examination of Alloy 600/82/182 butt weld locations on the pressurizer will be performed. The administrative controls will be required until completion of the scheduled mitigation activities for the BVPS Unit No. 1 pressurizer Alloy 600/82/182 nozzle butt welds (1R18).
i In the fall 2007 refueling outage (1R18) for BVPS Unit No. 1 Prior to the start of the fall 2007 refueling outage (1 RI 8) for BVPS Unit No. 1 Prior to February 28, 2007