ML110250259
| ML110250259 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/20/2011 |
| From: | Price J Dominion, Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-718, FOIA/PA-2011-0115 | |
| Download: ML110250259 (26) | |
Text
Dominion Nuclear Connecticut, Inc.
5000 Dominion Boulevard, Glen Allen, Virginia 23060 Web Address: www.dom.com January 20, 2011 U. S. Nuclear Regulatory Commission Serial No.10-718 Attention: Document Control Desk NSSLA/DC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUESTS FOR LIMITED COVERAGE EXAMINATIONS PERFORMED IN THE SECOND 10-YEAR INSPECTION INTERVAL As part of the inservice inspection (ISI) program, Dominion Nuclear Connecticut, Inc. (DNC) submitted a letter dated April 19, 2010 requesting approval for Relief Requests IR-2-51, IR-2-52, IR-2-53, IR-2-54, IR-2-55, IR-2-56, IR-2-57, IR-2-58, IR-2-59, and IR-2-60 for relief for limited coverage examinations performed in the second 10-year inservice inspection interval for Millstone Power Station Unit 3 (MPS3). Relief was requested on the basis that the required examination coverage is impractical due to physical obstructions and limitations imposed by the design, geometry and materials of construction of the subject components.
In a letter dated November 29, 2010, the NRC transmitted a request for additional information (RAI). It was agreed DNC would respond to the RAI by January 20, 2011.
Attachment 1 provides the DNC response to the NRC RAI addressing questions 1 through 10.
If you have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.
Sincerely, J. a Price Vii e resident- Nuclear Engineering
,A047r KOýg
Serial No.10-718 Docket No. 50-423 RAI Response for RRs for Limited Coverage Examinations Page 2 of 2 Attachments:
- 1. Response to Request for Additional Information Regarding Relief Requests for Limited Coverage Examinations Performed in the Second 10-Year Inspection Interval
- 2. Typical Reactor Pressure Vessel Shielding Panel Arrangement and Weight of Each Panel Commitments made in this letter:
- 1. None cc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 C. J. Sanders Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop O-8B3 Rockville, MD 20852-2738 NRC Senior Resident Inspector (w/o attachments)
Millstone Power Station
Serial No.10-718 Docket No. 50-423 RAI Response for RRs for Limited Coverage Examinations ATTACHMENT I RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUESTS FOR LIMITED COVERAGE EXAMINATIONS PERFORMED IN THE SECOND 10-YEAR INSPECTION INTERVAL DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 1 of 19 Question 1 IR-2-51, ASME Code, Section Xl,,Examination Category B-A, Items B1.11, B1.12, B13.21, and B1.22, Pressure Retaining Welds in Reactor Vessel a) Based on the limited descriptions and sketches provided in the licensee's submittal, it appears that examinations for ASME Code, Section, XI, Table IWB 2500-1, Category B-A, Items B1.11, B1.12, B1.21, and B1.22 were performed from the inside surface of the reactor pressure vessel (RPV).
State whether access to the subject.welds from the outside of the RPV is possible, and discuss the potential for increasing, ASME Code volumetric coverage by applying examinations from the outside surface of the RPV.
b) Discuss whether other welds in ASME Code, Section Xl, Examination Category B-A have been examined to the full, ASME Code-required volumetric extent, whether any indications were found as a result of these examinations, and the final disposition of the indications.
c) Verify that the descriptions below the coverage sketches for longitudinal welds in Attachment 1, pages 8 and 10, should be labeled ASME Code, Section Xl, Examination Category B-A, Item B1.12, and not B1.21 as currently shown.
DNC Response a) The subject weld examinations were performed from the inside surface of the reactor pressure vessel (RPV). Although possible, examination from the outside of the vessel is not practical due to the restrictions present on the outside surface of the vessel and the high radiation dose rate present in the area as discussed below. To attempt to perform additional weld examinations on these welds would result in a significant increase in radiation exposure to personnel that would not provide a compensating increase in the level of quality and safety.
The examinations of the Upper Shell Longitudinal Seam welds 101-122A, 101-122B and 101-122C were limited on the inside surface due to the obstruction caused by the outlet and inlet nozzle boss on the interior surface of the vessel. A similar restriction would be encountered with the nozzle geometry on the outside surface of the vessel. Additionally, insulation consisting of neutron shield panels is in place that inhibits access to the outside surface of these welds. These panels cover the outside surface of the RPV shell, RPV nozzles and RPV nozzle supports and are constructed of stainless steel plate filled with shielding material consisting of borated silicone rubber. A sketch of the typical shielding panel arrangement and listing of the weight of each panel is provided in Attachment 2 of this
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 2 of 19 response. The individual pieces to be removed for this examination range in weight from 230 lbs to 3520 lbs and are assembled in a sequence such that all panels for the nozzles, nozzle supports and the vessel shell in the areas of the subject welds would need to be removed to gain access to these welds.
Due to the high dose rates in the area, an attempt to improve examination coverage of these welds would result in a significant increase in personnel radiation exposure based on the time required for installation and removal of specialized rigging, insulation removal and replacement, weld surface preparation and weld examination.
Note that this justification, impracticality due to weight and configuration associated with removal of the panels from the RPV nozzles and the associated high dose rates, was the basis discussed in a previous request for relief from visual examination of the RPV nozzle-to-safe-end welds (IR 10 Rev. 1, which was approved on April 16, 2010, ADAMS Accession Number ML100820062).
The Lower Shell-to-Bottom Head Torus weld 101-141 and Torus Peel Segment weld 101-154C examinations were limited due to the core support lugs located on the inside surface that obstructed the scans of the welds in these areas. Coverage may be potentially increased by examination from the outside surface, however, due to the high radiation dose rate in the area, significant radiation exposure would be received in an attempt to do so. The Torus Peel Segment welds 101-154A and 101-154B, and the Torus-to-Dollar Plate weld 102-151 examinations are limited on the inside surface due to the incore instrumentation nozzles. Similar limitations would be encountered for examination from the outside surface due to the incore instrument housings that penetrate the outside surface of the vessel. Additionally, due to the high radiation dose rate in the area, an attempt to improve examination coverage of these welds would result in a significant increase in personnel radiation exposure due to the time required for erection and removal of staging platforms, weld surface preparation and weld examination.
b) The additional Category B-A welds examined, the extent of coverage, and examination results are listed below.
Weld Percent Identification Configuration Coverage Examination Results Flange-to-Upper Shell Two (2) recordable 101-121 Circ weld 100 subsurface indications evaluated as acceptable per IWB-3510-1 103-121 Upper-to-Intermediate 100 No recordable indications Shell Circ weld
ISerial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 3 of 19 Weld Percent Identification Configuration Coverage Examination Results Identirmcation-toveoage 101-171 Intermediate-to-Lower 100 No recordable indications Shell Circ weld Intermediate Shell No recordable indications 101-124A Longitudinal weld (90 100 degrees (deg.))
Intermediate Shell Five (5) recordable 101-124B Longitudinal weld (210 100' subsurface indications deg.) evaluated as acceptable per IWB-3510-1 Intermediate Shell Three (3) recordable 101-1240 Longitudinal weld (330 subsurface indications deg.) evaluated as acceptable per IWB-3510-1 Lower Shell No recordable indications 101-142A Longitudinal weld (90 100 deg.)
Lower Shell One (1) recordable Longitudinal weld (210 subsurface indication 101-142B deg.) 100 evaluated as acceptable per IWB-3510-1 Lower Shell No'recordable indications 101-142C Longitudinal weld (330 100 deg.)
Lower Head No recordable indications 101-154D Meridional weld (270 100 deg.)
c) The correct Item Number is B1.12 and the referenced coverage sketches are in error. A condition report has been entered into the Millstone Corrective Action Program to address the examination documentation error (CR408797).
Question 2 IR 2-52, ASME Code, Section Xl, Examination Category B-B, Items B2.11 and B2.40, Pressure Retaining Welds in Vessels Other Than Reactor Vessels a) As applicable, describe Nondestructive Examination (NDE) equipment (ultrasonic (UT) scanning apparatus) and details of the listed obstructions (size, shape, proximity to the weld, etc.) to demonstrate accessibility limitations. Discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 4 of 19 b) Fully clarify the wave modality and insonification angles used for all ultrasonic examinations.
c) Discuss whether similar welds in ASME Code, Section Xl, Examination Category B-B have been examined to the full, ASME Code-required extent, whether any indications were found asa resultrof these full examinations, and the final disposition of the indications.
d) Please also state the materials of construction and the wall thicknesses for the subject pressurizer (PZR) shell-to-head weld and steam generator (SG),
tubesheet-to-head weld.'
DNC Response a) Manual ultrasonic scanning techniques were performed using pulse-echo ultrasonic instruments and transducers.,
Examination of the Steam Generator Tubesheet-to-Head weld was restricted on the tubesheet side of the weld due to the location of the permanent tubesheet that limits the 45 deg. and 60 deg. scanning on that side of the weld to 5.5 inches from the centerline of the weld to the tube sheet flange.
Additionally the examination was limited by four steam generator vertical supports that limit scanning by 12" at each location every 90 deg. around the generator. These supports are positioned such that there is not enough space between the support member'and the weld to perform the examination scans in these areas.
Examination of the Pressurizer Shell-to-Upper Head weld was restricted by the vertical members of the safety valve restraint that obstructs 1.9" of the 0, 45 and 60 deg. scanning in all directions at each of four locations around the circumference of the pressurizer. This restraint is extremely large with a weight of approximately 10,000 pounds. The supportwould require disassembly and removal to increase the examination coverage for this weld.
However, due to the massive physical size of the support, it would require specialized rigging and handling techniques to attempt removal. Due to the size of the support, its movement during the removal activity would provide a potential to damage adjacent plant equipment. Reinstallation with critical alignments would also be a concern. In addition, the support is configured in such a manner that the pressurizer safety piping route through the support
,members, requiring removal of the pressurizer safety valves and associated piping in order to remove the support. Additionally, examination was also restricted by seven 2"x 2" permanently welded plates that are located in the examination' zone to provide support for the insulation panel retaining ring and four permanent 3" diameter pressurizer instrument taps that are original to the design on the pressurizer.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 5 of 19 The code required volume of these welds was interrogated ultrasonically to the maximum extent possible. No alternative methods or advanced technologies were considered capable of increasing the ASME code coverage.
b) The wave mode and insonification angles are listed below.
Weld Identification Configuration Angle Mode 03-007-SW-J Pressurizer Shell-to- 0. Longitudinal Wave Upper Head weld 450 and 600 Shear Wave 03-003-SW-Z Steam Generator 00 Longitudinal Wave Tubesheet-to-Head weld 450 and 60' Shear Wave c) The additional Category B-B welds examined, the extent of coverage, and examination results are listed below.
Weld Configuration Percent Examination Identification Coverage Results Pressurizer Head- No recordable 03-007-SW-F to-Lower Shell indications Circumferential 96.6i o weld Pressurizer Lower No recordable 03-007-SW-Y Shell Longitudinal 100 indications weld @ 280 Az.
Pressurizer Upper No recordable 03-007-SW-Z Shell Longitudinal 100 indications weld @ 40 Az.
d) The steam generator tubesheet is constructed of SA508, Class 2a carbon steel and the channel head is constructed of SA533, GR. B-Cl. 1 carbon steel with a nominal wall thickness of 5 inches.
The pressurizer head and shell are constructed of SA533, Grade A, Class 2 carbon steel material with internal stainless steel cladding with a nominal wall thickness of 3 inches.
Question 3 IR-2-53, ASME Code, Section Xl, Examination Category B-D, Items B3.90, B3.100, and B3.130, Full Penetration Welded Nozzles in Vessels It is unclear from the information in the licensee's submittal which UT wave mode corresponds to each insonification angle. Please clarify the wave modality and insonification angles used for all UT examinations performed on the RPV, PZR, and
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 6 of 19 SG nozzle-to-head welds listed in ASME Code,Section XI, Examination Category B-D.
DNC Response a) The wave modes and corresponding insonification angles are listed below.
Component Configuration Angle Mode 03-006-SW-U Steam Generator 00 Longitudinal Wave Outlet Nozzle-to- 450 and 600 Shear Wave Head weld 03-006-SW-V Steam Generator 00 Longitudinal Wave Inlet Nozzle-to-Head 450 and 60' Shear Wave weld 03-007-SW-A Pressurizer Safety 00 Longitudinal Wave Nozzle-to-Head 450 and 600 Shear Wave weld 03-007-SW-B Pressurizer Safety. 00 Longitudinal Wave Nozzle-to-Head 45' and 600 Shear Wave
_weld 03-007-SW-C Pressurizer Safety 00 Longitudinal Wave Nozzle-to-Head 450 and 600 Shear Wave weld 03-007-SW-D Pressurizer Relief 0' Longitudinal Wave Nozzle-to-Head 450 and 600 Shear Wave weld 03-007-SW-E Pressurizer Spray 00 Longitudinal Wave Nozzle-to-Head 450 and 600 Shear Wave weld 03-007-SW-S Pressurizer Surge 00 Longitudinal Wave Nozzle-to-Head 450 and 600 Shear Wave weld 107-121A RPV Outlet Nozzle- 150, 450 and 700 Longitudinal Wave to-Shell weld 450 Shear Wave 107-121B RPV Outlet Nozzle- 150, 450 and 700 Longitudinal Wave to-Shell weld 450 Shear Wave 107-121C RPV Outlet Nozzle- 150, 450 and 700 Longitudinal Wave to-Shell weld 450 Shear Wave 107-121D RPV Outlet Nozzle- 150; 450 and 700 Longitudinal Wave to-Shell weld 450 Shear Wave
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 7 of 19 Question 4 IR-2-54, ASME Code, -Section XI, Examination Category B-H, Item B8.20, Integral Attachments for Vessels Please state the materials of construction and what type of surface examination was performed (liquid penetrant (PT) or magnetic particle (MT) for the integrally welded attachments to the PZR.
DNC Response The pressurizer shell is constructed of SA533, Grade A, Class 2 carbon steel and the attachment lugs are SA533, Grade A, Class 1 carbon steel.
Magnetic particle (MT) examination was performed on these integrally welded attachments.
Question 5 IR-2-55, ASME Code, Section Xl, Examination Category C-A, Item C1.20, Pressure Retaining Welds in Pressure Vessels a) As applicable, describe NDE equipment (UT scanning apparatus) and details of the listed obstructions (size, shape, proximity to the weld, etc.) to demonstrate accessibility limitations. Discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.
b) Fully clarify the wave modality and insonification angles used for all ultrasonic examinations.
c) Please also state the materials of construction and the wall thickness for the Residual Heat Removal heat exchanger.
DNC Response a) Manual ultrasonic scanning techniques were performed using pulse-echo ultrasonic instruments and transducers.
The subject obstructions consist of a reinforcing plate on the inlet and the outlet nozzle of the heat exchanger. These reinforcing plates are permanently welded to the nozzle and to the heat exchanger shell as part of the original heat exchanger design. These plates are located on the shell side of the heat exchanger in close proximity to the subject head-to-shell weld. There is not enough distance between the reinforcing plates and the subject weld to perform any shell side scans for a distance of 25.5 inches at each of these two plate locations.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 8 of 19 The code required volume of these welds was interrogated ultrasonically to the maximum extent possible. No alternative methods or advanced technologies were considered capable of increasing the ASME code coverage.
b) The wave mode and corresponding insonification angles are listed below.
Component Configuration Angle Mode 03-073-008 "A" RHR Heat 450 Shear Wave Exchanger Lower 70' Longitudinal Wave Head-to-Shell weld c) The Residual Heat Removal heat exchanger lower head and shell are constructed of Type 304 stainless steel with a nominal thickness of .78 inches.
Question 6 IR-2-56, ASME Code,Section XI, Examination Category C-C, Item C3.20, integral Attachments for Vessels, Piping, Pumps, and Valves' a) Please state the materials of construction and what type of surface examination was performed (PT or MT) for each of the integrally welded attachments to ASME Code Class 2 piping.
b) Please verify that the ASME table is IWC-2500, not IWB-2500 as stated in Section 3 and Section 6.
DNC Response a) The piping and the attachment lug material are Type 304 stainless steel.
Liquid penetrant (PT) was the surface examination method performed for the integral attachments listed in request IR-2-56.
b) The correct table reference is IWC-2500.
Question 7 IR-2-57, ASME Code,Section XI, Examination Category C-F-i, Items C5.1 and C5.21, Pressure Retaining Welds in Austenitic Stainless Steel or High Alloy Piping a) As applicable, describe NDE equipment (UT scanning apparatus) and details of the listed obstructions (size, shape, proximity to-the weld, etc.) to demonstrate
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 9 of 19 accessibility, limitations. Discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.
b) Fully clarify the wave modality and insonification angles used for all ultrasonic examinations.
c) Please confirm that the required surface examinations (PT or MT) were performed for the subject welds, whether these surface examinations were full ASME Code examinations (>90% coverage), and describe any indications that were detected.
d) Confirm that all examinations listed in ASME Code,Section XI, Examination Category C-F-i, were conducted in accordance with the performance demonstration requirements described in ASME Code, Section Xl, Appendix VIII.
DNC Response a) Manual ultrasonic scanning techniques were performed using pulse-echo ultrasonic instruments and transducers qualified in accordance with ASME, Section Xl, Appendix VIII as implemented by the Performance Demonstration Initiative (PDI).
The listed piping welds are restricted from full examination from both sides of the weld due to the component configurations consisting of either a valve, flange, tee, or nozzle on one side of the weld -which inhibits scanning on that side of the weld. The limitations are primarily due to the taper of the component as'it transitions to the weld. With the slope of this taper located within such close proximity to -the weld, no meaningful examination results could be obtained in the area of this taper.
In addition to the limitation due to-the tapered component surfaces, the following welds also encountered further limitations as described below.,
QSS-3-FW-5BR "Flange-to-Pipe" - Welded pipe support on the pipe side of the weld that further reduced the coverage obtained from the pipe side.
axial scan.
QSS-6-4-SW-D "Pipe-to-Flange" - Weldolet on the pipe side of the weld that further reduced the coverage obtained from the pipe side circumferential and axial scans.
RSS-1 9-4-SW-G "Reducer-to-Nozzle weld" - Weldolet on the reducer side of the weld that further reduced the coverage obtained from the reducer side axial scan.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 10 of 19 RSS-21-4-SW-G "Reducer-to-Flange" - Weldolet on the reducer side of the weld that further reduced the coverage obtained from the reducer side axial scan.
SIL-25-FW-2 "Valve-to-Pipe" - Weldolet on the pipe side of the weld that further reduced the coverage obtained from the pipe side circumferential and axial scans.
Weld CHS-507-10-SW-1 1 is the only weld listed in this request that is not affected by a component with a tapered surface. The limitations for this weld are described below.
CHS-507-1 0-SW-1 1 "Elbow-to-Tee" - Limited scanning at the tight inside radius of the small diameter elbow reduced the coverage obtained from the elbow side circumferential and axial scans. Additional restriction due to the branch of the tee that reduced the coverage obtained from the tee side circumferential and axial scans.
The ASME code required volume of these welds was interrogated ultrasonically to the maximum extent possible. No alternative methods or advanced technologies were considered capable of increasing the ASME code coverage.
b) The wave mode and insonification angles used for the UT inspections are listed below.
Weld Configuration Angle Mode Identification CHS-30-11-SW-E 6" Pipe-to-Flange 600 and 70' Shear Wave CHS-30-12-SW-B 6" Pipe-to-Flange 600 and 700 Shear Wave CHS-30-12-SW-C 6" Flange-to-Pipe 600 and 700 Shear Wave CHS-30-13-SW-B 6" Flange-to-Elbow 600 and 70° Shear Wave CHS-507-1 0-SW-1 1 4" Elbow-to-Tee 450 Shear Wave 700 Longitudinal Wave CHS-507-FW-19 4" Pipe-to-Valve 450 Shear Wave 700 Longitudinal Wave QSS-3-4-SW-K 12" Pipe-to-Flange 45" and 70" Shear Wave QSS-3-FW-5BR 12" Flange-to-Pipe 450 and 70' Shear Wave QSS-6-3-SW-D 14" Pipe-to-Flange 60" and 700 Shear Wave QSS-6-4-SW-B 14" Flange-to-Elbow 450 and 70" Shear Wave QSS-6-4-SW-D 14" Pipe-to-Flange 60" and 70" Shear Wave RHS-501 -FW-6 12" Valve-to-Pipe 450 Shear Wave 60" Longitudinal Wave RHS-502-FW-7 12" Valve-to-Pipe 45" Shear Wave 1 60" Longitudinal Wave
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 11 of 19 Weld Identification Configuration Angle Mode RHS-6-2-SW-K 14" Pipe-to-Flange 450 and 700 Shear Wave RHS-6-FW-4 14" Pipe-to-Pump 450 and 700 Shear Wave Nozzle RSS-11-2-SW-B 16" Flange-to-Elbow 450 and 70' Shear Wave RSS-1 SW-B 12" Flange-to-Pipe 600 and 70° Shear Wave RSS-1 5-3-SW-B 12" Valve-to-Pipe 450 and 700 Shear Wave RSS-16-2-SW-B 12" Valve-to-Pipe 450 and 700 Shear Wave RSS-19-4-SW-G 16" Reducer-to-Nozzle 600 and 700 Shear Wave RSS-21-4-SW-G 16" Reducer-to-Flange 60° and 70' Shear Wave RSS-8-2-SW-R 16" Flange-to-Elbow 60' and 70' Shear Wave SIH-12-3-SW-C 6" Pipe-to-Flange 600 and 70' Shear Wave SIH-12-FW-3 6" Pipe-to-Valve 600 and 70' Shear Wave SIH-4-3-SW-B 4" Flange-to-Pipe 450 and 600 Shear Wave 700 Longitudinal Wave SIL-11-FW-3 8" Valve-to-Pipe 450 Shear Wave 700 Longitudinal Wave SIL-152A-FW-1 24" Flange-to-Pipe 600 and 700 Shear Wave SIL-25-FW-1-SM 8" Pipe-to-Tee 450 Shear Wave 600 Longitudinal Wave SIL-25-FW-1-8M 8" Pipe-to-Tee 450 Shear Wave 600 Longitudinal Wave SIL-25-FW-2 8" Valve-to-Pipe 450 Shear Wave 600 Longitudinal Wave SIL-25-FW-3 8" Valve-to-Pipe 45" Shear Wave 600 Longitudinal Wave SIL-40-FW-1 6" Valve-to-Pipe 45' and 600 Shear Wave 600 Longitudinal Wave SIL-9-FW-1 6" Pipe-to-Valve 450 Shear Wave 600 Longitudinal Wave c) DNC received approval to use Code Case N-663, "Alternative Requirements for Classes I and 2 Surface Examinations", during the second 10-year inspection interval. A portion of the welds listed in this request were evaluated and determined to not require surface examination in accordance with Code Case N-663. The remaining welds listed in this request were examined prior to implementation of this code case and the code required surface examinations were performed. The welds that received the required surface examination are listed below.
Weld Configuration; Percent Examination Identification Coverage Results SCHS-507-10-SW-11 4" Elbow-to-Tee 100 No recordable indications CHS-507-FW-19 4" Pipe-to-Valve 100 No recordable indications
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 12 of 19 Weld Configuration Percent Examination.
Identification Coverage Results One recordable indication consisting of QSS-3-4-SW-K 12" Pipe-to-Flange 100 a 1/8" rounded-indication evaluated as acceptable No recordable QSS-3-FW-5BR 12" Flange-to-Pipe 100 Ndicatin indications No recordable RHS-6-2-SW-K 14" Pipe-to-Flange 100 Ndic atin indications RHS-6-FW-4 14" Pipe-to-Pump 100 No recordable Nozzle indications No recordable Ndicatin RSS-1 1-2-SW-B 16" Flange-to-Elbow 100 indications RSS-15-3-SW-B No recordable 12" Valve-to-Pipe 100 indications SIH-4-3-SW-B 4" Flange-to-Pipe 100 incaos No recordable indications No recordable SIL-1 1-FW-3 8" Valve-to-Pipe 100 indications No recordable Ndicatin SIL-40-FW-1 6" Valve-to-Pipe 100 indications No recordable SIL-9-FW-1 6" Pipe-to-Valve 100 Ndicatin indications d) Examinations of the Category C-F-1 welds listed were conducted in accordance with performance demonstration requirements of ASME Code Section Xl, Appendix VIII as implemented through the PDI.
Question 8 IR-2-58, ASME Code, Section Xl, Examination Category F-A, Item F1.40, Supports The basis for this request is conflicting.
a) DNC stated that there is a permanent obstruction caused by the RPV insulation panels and that the area is difficult to access due to the cavity seal ring needing to be modified or removed. The licensee also discusses the radiation exposure that would result in the modification and/or removal of the permanent obstruction (RPV insulation panels). It appears to the NRC staff that the subject obstructions can be removed, therefore, the licensee needs to provide additional information to clarify why it is impractical to perform the ASME Code-required examination. Also, further explanation of what the burden associated with modifying or removing cavity seal ring is needed.
Serial No.10-718 MPS3 RAI Response for RRs for Limited. Coverage Examinations Attachment 1, Page 13 of 19 b) What is the total man-rem associated with this examination, including modification and/or removal of the permanent cavity seal ring to access the support, the removal and reinstallation of the permanent obstructions (RPV panels), and any other preparations/examination times that are required?
DNC Response a) The RPV insulation panels consist of neutron shield package panels that are bolted in place and inhibit access to the surface of these supports. These panels cover the outside surface of the RPV nozzles and nozzle supports and are constructed of stainless steel plate filled with shielding material consisting of borated silicone rubber. There are eight individual panels covering the RPV nozzle and nozzle supports that would need to be removed for each of the four support locations. A sketch of the typical shielding panel arrangement and listing of the weight of each panel is provided in Attachment 2 of this response.
Note that it is not anticipated that panels labeled number 1 and number 2 would need to be removed for this examination. The individual pieces to be removed for this examination range in weight from 230 lbs to 1200 lbs and are assembled in a sequence such that panels for the nozzles and nozzle supports need to be removed to gain access to visually inspect the subject supports.
Removal of the panels is further complicated by their location in the restricted area under the permanently welded cavity seal ring. These panels have not been removed since original construction. Due to the size and weight of these panels and their location in the confined area under the cavity seal ring, it has been consistently considered an impracticality to remove these panels without
.removing or modifying the cavity seal ring. Specifically, the cavity seal ring would need to be modified or sections removed to gain the necessary access for the rigging equipment required to remove these panels. Upon further evaluation, it has been determined that it may be possible to remove panels for inspection without modification or removal of the cavity seal ring by setting up specialized rigging equipment through the existing seal ring manways.
Therefore, the identified additional burden associated with modifying or removing the cavity seal ring is no longer valid justification in the determination of impracticality. However, the burden and dose associated with removal of the panels required for inspection remains for this approach. DNC is evaluating other techniques which may address the issue of impracticality for future examinations.
A sketch of the typical shielding panel arrangement and listing of the weight of each panel is provided in Attachment 2 of this response. Note that it is not anticipated that panels labeled number 1 and number 2 would need to be removed for this examination.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 14 of 19 b) Following the further evaluation of the effort to remove the applicable shielding panels, the total man-rem estimate associated with performing this examination has been revised. The revised estimate based, on rigging setup and removal, shielding panel removal and reinstallation, and the support visual examination time would result in approximately 26.08 man-rem of exposure.
As previously stated in "a)" above, further evaluation has indicated that the need for potential modification/removal of the cavity seal is no longer anticipated and therefore, there is no dose estimate associated with this previously anticipated activity.
Question 9 IR-2-59, ASME Code,Section XI, Examination Category R-A, Items R1.11 and R1.20, Risk Informed Piping Examinations a) Please submit detailed and specific information to support the bases for limited volumetric coverage in ASME Code,Section XI, Examination Category R-A piping welds, and thereby, demonstrate impracticality.
b) As applicable, describe NDE equipment (UT scanning apparatus) and details of the listed obstructions (size, shape, proximity to the weld, etc.) to demonstrate accessibility limitations. Discuss whether alternative methods or advanced technologies could be employed to maximize ASME Code coverage.
c) Fully clarify the wave modality and insonification angles used for all UT examinations.
d) Please state the materials of construction for the welds and base materials.
e) Please confirm whether the examinations listed for all ASME Code,Section XI, Examination Category R-A welds were conducted in accordance with the performance demonstration requirements of ASME Code, Section X1, Appendix VIII.
f) Confirm that all of the ASME Code, Section Xl, Examination Category R-A welds are Item RI.11 (elements subject to thermal fatigue) and R1.20 (elements not subject to a known damage mechanism) per ASME Code Case N-577 1, as shown in the licensee's table.
g) Further discuss whether additional or alternative welds could have been examined to augment the reduced volumetric coverage resulting from the limited examinations of the subject welds.
ASME Code Case N-577 has not been approved for use in RG-1.147, Revision 15. Licensees base their RI-ISI inspection sample size and examination methodology on Table 1 of ASME Code Case N-577.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 15 of 19 DNC Response a) The piping weld examinations listed in this request are limited to a one-sided examination due to the limitation of a tapered surface from a valve or nozzle that exists on one side of each of the welds which precludes any meaningful scanning results from that side.
For austenitic welds where examinations from both sides are not possible, 10CFR50.55a(b)2(xv)(A)(2) requires full coverage credit from a single side may be claimed only after completing a successful single-sided Appendix VIII demonstration using flaws on the opposite side of the weld. There are currently no qualified PDI procedures for single-sided austenitic weld examinations to detect flaws on the far side of the weld, therefore, the allowable codecoverage credit for the subject welds is limited to 50 percent.
b) Manual ultrasonic scanning techniques were performed using pulse-echo ultrasonic instruments and transducers qualified in accordance with ASME Section Xl, Appendix VIII as implemented by the PDI.
The listed piping welds are restricted from full examination from both sides of the weld due to the component configurations consisting of a valve or nozzle on one side of the weld which inhibits scanning on that side of the weld. The limitations are due to the taper of the component as it transitions to the weld. With the slope of this taper located within such close proximity to the weld, no meaningful examination results could be obtained in the area of this taper.
The code required volume of these welds was interrogated ultrasonically to the maximum extent possible. No alternative methods or advanced technologies were considered capable of increasing the ASME code coverage.
c) The wave mode and insonification angles used for the UT inspections are listed below.
Weld Identification Configuration Angle Mode 408044-FW-10-1 1.5" Pipe-to-Valve 450 and 700 Shear Wave 408044-FW-5 1.5" Valve-to-Pipe 450 and 700 Shear Wave RCS-1 50-FW-2 2" Valve-to-Pipe 45' and 700 Shear Wave RCS-15-FW-28 27.5" Pipe-to-Valve 450 Longitudinal Wave RCS-504A-FW-4 8" Pipe-to-Valve 450 Shear Wave 600 Longitudinal Wave RCS-504C-FW-4 8"Pipe-to-Valve 450 Shear Wave 600 Longitudinal Wave RCS-513-FW-25 3'" Valve to-Pipe 450 and 700 Shear Wave RCS-513-FW-29 3" Valve-to-Pipe 450 and 700 Shear Wave RCS-5-FW-8 27.5" Pipe-to-Valve , 450 Longitudinal Wave
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 16 of 19 Weld Identification Configuration Angle Mode RCS-10-FW-18 27.5" Pipe-to-Valve 450 Longitudinal Wave RCS-20-FW-38 27.5" Pipe-to-Valve 450 Longitudinal Wave RCS-LP2-HL1-SW-C 29" Pipe-to-Nozzle 450 Longitudinal Wave 450 Shear Wave RCS-LP3-FW-27 6" Valve-to-Pipe 600 Longitudinal Wave RCS-LP4-FW-HL1-CMR 29" Pipe-to-Nozzle 450 Longitudinal Wave 450 Shear Wave RHS-501-FW-3 12" Valve-to-Pipe 600 Longitudinal Wave RHS--502-FW-3 12" Valve-to-Pipe 450 and 600 Shear Wave 600 Longitudinal Wave SIL-13-FW-5 6" Pipe-to-Valve 450 and 600 Shear Wave 600 Longitudinal Wave SIL-4-FW-10 10" Pipe-to-Valve 450 and 700 Shear Wave 450 Longitudinal Wave SIL-5-FW-10 10" Pipe-to-Valve 450 and 600 Shear Wave SIL-6-FW-10 450 600 and 700 Shear Wave Wave Longitudinal SI L-6-FW-i 0 10" 10"; Pipe-to.-Valve Pipe-to-Valve 450 450 and 700 LongtdnlWv Shear Wave
_ 450 Longitudinal Wave d) The materials of construction for the weld and base materials are listed below.
Weld Identification Base Material Weld Material 408044-FW-10-1 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.9 ER316 408044-FW-5 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.9 ER316 RCS-150-FW-2 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.9 ER316 RCS-15-FW-28 SA351/CF8A(304) SA351/CF8M(316) SFA 5.4 E308 and (Pipe) (Valve) SFA 5.9 ER308 RCS-504A-FW-4 SA376/TP304 (Pipe) SA351/CF8M(316) SFA 5.4 E308 and (Valve) SFA 5.9 ER308 RCS-504C-FW-4 SA3761TP304 (Pipe) SA351/CF8M(316) SFA 5.4 E308 and (Valve) SFA 5.9 ER308 RCS-513-FW-25 SA376/TP316 (Pipe) SA351/CF8M(316) SFA 5.9 ER316 (Valve)
RCS-513-FW-29 SA376/TP316 (Pipe) SA351/CF8M(316) SFA 5.9 ER316 (Valve)
RCS-5-FW-8 SA351/CF8A(304) SA351/CF8M(316) SFA 5.4 E308 and (Pipe) (Valve) SFA 5.9 ER308 RCS-10-FW-18 SA351/CF8A(304) SA351/CF8M(316) SFA 5.4 E308 and (Pipe) (Valve) SFA 5.9 ER308 RCS-20-FW-38 SA351/CF8A(304) SA351/CF8M(316) SFA 5.4 E308 and (Pipe) (Valve) SFA 5.9 ER308 RCS-LP2-HL1-SW-C SA351/ CF8A(304) SA182/F316N (Nozzle) SFA 5.4 E308 and
-(Pipe) SFA 5.9 ER308 RCS-LP3-FW-27 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.9 ER316 RCS-LP4-FW-HL1-CMR SA351/CF8A (304) SA182/F316N (Nozzle) SFA 5.4 E308 and (Pipe) SFA 5.9 ER308
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 17 of 19 Weld Identification Base Material Weld Material RHS-501-FW-3 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.4 E316 and SFA 5.9 ER316 RHS--502-FW-3 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.4 E316 and SFA 5.9 ER316 SIL-13-FW-5 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.4 E316 and SFA 5.9 ER316 SIL-4-FW-10 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.4 E316 and SFA 5.9 ER316 SIL-5-FW-10 SA376/TP316 (Pipe) SA182/F316 (Valve) SFA 5.4 E316 and SFA 5.9 ER316 SIL-6-FW-10 SA376/TP316 (Pipe) SA351/CF8M(316) SFA 5.4 E316 and (Valve) SFA 5.9 ER316 e) The listed examinations for Examination Category R-A welds were conducted in accordance with performance demonstration requirements of ASME Section XIl Appendix VIII as implemented through the PDI with the exception of those welds containing cast stainless steel piping material in which no qualified ultrasonic
- examination procedure exists. The examination of the cast stainless steel material was performed in accordance with ASME Section Xl, Appendix I and Appendix Ill.
f) The ASME Code, Section Xl, Examination Category R-A welds listed in the request are Item R1.11 (elements subject to thermal fatigue) and R1.20 (elements not subject to a known damage mechanism) consistent with ASME Code Case N-577, Table 1.
g) Two of the welds listed were preservice examinations as identified in Table 1 of Relief Request IR-2-59. The performance of alternative or additional examinations would not apply.
Welds within Item number R1.20 are located in segments with other welds that could be examined; however, the welds in these segments are also similarly limited to a one-sided exam from the pipe side only. Performing alternative or additional examinations, interrogating the same limited weld volume as the subject weld is considered to provide no additional benefit.,
Welds within Item number R1.11 are within segments subject to thermal fatigue.
The subject weld was chosen as the location with the highest susceptibility to thermal fatigue. The completed examination of the weld and the piping side base metal near the weld provides substantial evidence for lack of active thermal fatigue cracking. Choosing another location in the segment with no potential active mechanism as an alternative or additional examination would not provide an increase in confidence that thermal fatigue is not active. As a consequence, performing additional weld examinations in the segments of Item
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 18 of 19 numbers R1.11 and R1.20 would result in an increase in radiation exposure that would not provide a compensating increase in the level of quality and safety.
Question 10 IR-2-60, ASME Code, Section Xl, Examination Category B-P, Item B15.11, All Pressure Retaining Components The following questions pertain to the 2 nd 10-year ISI interval at MPS3:
(a) The request provides proposed alternative means for detecting leakage of the RPV flange seal leak-off piping, however the interval the relief is requested for has already ended. Please explain what was done to detect leakage during the 2 nd 10-year interval at MPS3. Please explain why alternative information was provided.
(b) Provide the date(s) of the previous examinations of the RPV flange seal leak-off piping visual inspections and whether any indications of leakage were detected.
The following question pertains to the 1 st 10-year ISI interval at MPS3:
(c) The hydrostatic test of the RPV flange seal leak-off line was also required during the is 10-year interval at MPS3 (ASME Code of Record for the 1st interval is the 1983 Edition through the 1983 Summer Addenda). Please explain how the test was performed during the 1 st interval. Ifthe test was not performed, please explain what action has been taken and/or what action will be taken.
DNC Response a) It was not previously recognized that this piping was associated with Class 1, normally isolated lines that were required to be pressurized to RCS system operating pressure to meet this code requirement. This was identified near the end of the second inspection interval during the preparation for the third inspection interval submittal.
The RPV flange seal leak-off piping has been VT-2 visually examined during the RCS Class 1 system leakage test performed at the end of each refueling outage with the RCS system at normal operating pressure and temperature and the RPV flange seal leak-off piping in its normally unpressurized state. Additionally, due to the material of this line containing Alloy 600, a direct detailed visual examination has been performed at the beginning of each outage for the last four outages of the interval. This examination has been performed with the RCS cooled down and depressurized to allow a close up observation for the purpose of identifying any evidence of boric acid leakage.
Serial No.10-718 MPS3 RAI Response for RRs for Limited Coverage Examinations Attachment 1, Page 19 of 19 The proposed alternative which was submitted was meant to indicate the details of the VT-2 examination that was actually performed during the Class 1 system leakage test each refueling outage, however it was incorrectly worded as "will be performed each outage" rather than "has been performed each outage."
b) Outage 3R06 Examination during Class 1 system leakage test - 06/04/99 Outage 3R07 Examination during Class 1 system leakage test - 03/15/01 Outage 3R08 Examination during Class 1 system leakage test - 10/03/02 Outage 3R09 Detailed examination at beginning of refueling outage - 04/04/04 Examination during Class 1 system leakage test - 05/04/04 -
Outage 3R10 Detailed examination at beginning of refueling outage - 10/01/05 Examination during Class 1 system leakage test - 10/26/05 Outage 3R1 1 Detailed examination at beginning of refueling outage - 04/15/07 Examination during Class 1 system leakage test - 05/15/07 Outage 3R12 Detailed examination at beginning of refueling outage -10/16/08 Examination during Class 1 system leakage test - 11/17/08
.No indication of leakage was observed during these examinations.
c) During the first interval, the subject piping was examined in the normally unpressurized state at the end of each refueling outage during the required Class 1 system leakage test. A similar examination was performed during the hydrostatic test at the end of the interval using Code Case N-498-1. The requirements for pressurization of this normally isolated piping were not recognized at that time. As a result, the subject piping was not pressurized to the code required pressure during the first interval hydrostatic test.
Note that a similar request has been recently approved (IR-3-1 1, approved April 29, 2010, ADAMS Accession No. ML101040042) for the third 10-year inspection interval.
Serial No.10-718 Docket No. 50-423 RAI Response for RRs for Limited Coverage Examinations ATTACHMENT 2 TYPICAL REACTOR PRESSURE VESSEL SHIELDING PANEL ARRANGEMENT AND WEIGHT OF EACH PANEL DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3
Ba-*B-i
- ~N.*
B-i 0-B8-2 P
,- 85-2 Nozzle Number 3-RCS-029-16-1
-TRANSCO PRODUCTS, INC. I PROCEDURE NO. 5000.0121. PAGE -'1 FIGURE 3
TRANSCO PRODUCTS INC.
TABLE I NOTE: These calculated weights are to be used for the selection of rigging, hoisting and temporary supports. Appropriate Factors 'of Safety are to be applied.
MARK NUMBER WEIGH T MARK NUMBER WEIGH T CB-1 3, 520 lbs. BE-D-1 340 lbs.
CB-2 3, 520 BE-D-2 340 CC-A 3, 520 BE-E-I 340 CC-B 3, 440 BE-E-2 340 CD-A 3, 520 BG-A-i 675 CD-B 3,520 BG-A-2 675 CE-A 3, 520 BBG-B-1 395 CE-B 3, 610 BG -B -2 395 CN-A-1 .9 BG-C-2 395 CN-B-1 -9 BG-C-2 395 CN-A-2 19 BG-D-1 415 CN-B-2 19 BG-D-2 415
.BN-A-1 470 BG-E-I 415 BN-A-2 470 BG-E-2 415 BN-B-1 410 CF-A-1 230 BN-B-2 410 CF-A-2 230 BN-C-1 410 CF-B-I 480 BN-C-2 410 CF-B-2 480 BP-A-i 470 CF-C-I 480 BP-A-2 470 CF-C-2 480 BP-B-1 370 CG-A-1 230 BP-B-2 370 CG-A-2 230 BP-C-i 370 CG-B-1 480 BP-C-2 370 CG-B-2 480 BK-A-i 620 CG-C-1 480 BK-A-2 620 CG-C-2 480 BK-B-i 620 BH-A-i 1,200 BK-B-2 620 BH-B-i 1,200 BL-A-1 620 BH-A-2 1, 200 BL-A-2 620 BH-B-2 1,200 BL-B-1 620 BH-A-3 1,200 BL-B-2 620 BH-B-3 1,200 BE-A-1 590 BH-A-4 1,200 BE-A-2 590 BR-B-4 1,200 BE-B-I 710 BJ-AA-1 1,200 BE-B-2 710 BJ-AA -2 1,200 BE-C-i 730 BJ-AB-I 1,200 BE-C-2 730 BJ-AB-2 1,200 A CORPORATION OF THE TRANSCO GROUP
. TRANSCO PRODUCTS INC.
MARK NUMBER WEIGHT BJ-BA-I 1, 200 lbs.
BJ-BA-2 1,200 BJ-BB-1 1,200 BJ-BB-2 1,200 BB-1 510 BB-2 510 BB-3 510 BB-4 510 BC-A-1 415 BC-A-2 415 BC-B-1 415 BC-B-2 415 BD-A-J 415 BD-A -2 415 BD-B-1 415 BD-B-I 415 BS-1 140 BS-2 140 BT-1 90 BT-2 90 BV-i 110
-' BV-2 110 BW-1 120 BW-2 120 A CORPORATION OF THE TRANSCO GROUP