ML18101B062
| ML18101B062 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 10/17/1995 |
| From: | Eric Simpson Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-95-03, GL-95-3, LR-N95172, NUDOCS 9510250370 | |
| Download: ML18101B062 (9) | |
Text
Public Service Electric and Gas Company E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Senior Vice President - Nuclear Engineering OCT 1 7 1995 LR-N95172 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION GENERIC LETTER 95 CIRCUMFERENTIAL CRACKING OF STEAM GENERATOR TUBES SALEM GENERATING STATION UNITS 1 AND 2 FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 DOCKET NOS. 50-272 AND 50-311 Public Service Electric and Gas Company (PSE&G) submitted the response to Generic Letter (GL) 95-03, Circumferential Cracking of Steam Generator Tubes, to the NRC in letter LR-N95096 dated July 17, 1995.
By letter dated September 12, 1995, the NRC documented their initial review of this response and requested additional information to complete their review of GL 95-03.
PSE&G hereby submits the response to the NRC request for additional information for Salem Units 1 and 2 in.
Should you have any questions regarding this request, please do not hesitate to contact us.
Attachment (1)
@. Printed on
~
Recycled Paper 9510250370 951017 PDR ADOCK 05000272 P
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Document Control Desk LR-N95172
- c Mr. T. T. Martin, Administrator - Region I
- u. s. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. L. N. Olshan, Licensing Project Manager -
Salem U. s. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 Mr. c. s. Marschall (X24)
USNRC Senior Resident Inspector Mr. Kent Tosch, Manager, IV NJ Department of Environmental Protection Division of Environmental Quality Bureau of Nuclear Engineering CN 415 Trenton, NJ 08625 OCT 171995
REF: LR-N95172 STATE OF NEW JERSEY SS.
COUNTY OF SALEM E. c. Simpson, being duly sworn according to law deposes and says:
I am Senior Vice President - Nuclear Engineering of Public Service Electric and Gas Company, and as such, I find the matters set forth in the above referenced letter, concerning Salem Generating station Unit Nos. 1 and 2, are true to the best of my knowledge, information and belief.
(:(!~
Subscribedhand Sworn@r.~efore me this
/
~'l day of C!faU/:J...JLIL-, 1995 My Commission expires on KIMBERLY JO BROWN NOtAAY PUBLIC OF NEW JERSEY My Comm1ss;on Expires April 21, 1998
LR-:N95172 ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION GENERIC LETTER 95 CIRCUMFERENTIAL CRACKING OF STEAM GENERATOR TUBES SALEM GENERATING STATION UNITS 1 AND 2 FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR-75 DOCKET NOS. 50-272 AND 50-311
- 1.
NRC QUESTION For the inspections performed at the expansion transition during 2R8 and lRll, clarify if the percentages cited were the percentages of the total number of tubes in the steam generator or the number of tubes in Zone 4 (e.g., for steam generator 11 in lRll, does the 39% imply that 39% of all the tubes in the steam generator were examined with the examinations concentrated in Zone 4, or does the 39%.imply that 39% of the tubes in Zone 4 were examined?).
PSE&G RESPONSE The percentages cited in PSE&G's response to Generic Letter 95-03 (Letter LR-N95096 dated July 17, 1995) are based on the total number of tubes in the steam generators, and the number of tubes inspected were concentrated in Zone 4.
- 2.
NRC QUESTION It was indicated that 5 tubes have been plugged as a result of circumferential cracking.
Please clarify that all tubes with circumferential indications were removed from service.
Clarify the outages in which these indications were detected.
PSE&G RESPONSE In previous outages, PSE&G has plugged all tubes with circumferential indications.
The five (5) tubes that have been plugged as a result of inspections completed prior to the current outages were identified as follows:
Page 1 of 6
LR-:N95172 ATTACHMENT 1
- 3.
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 Steam Generator Outage Date No. of Salem 1 SG 14 1R9 1991 1
Salem 1 SG 11 lRll 1993 1
Salem 1 SG 13 lRll 1993 2
Salem 2 SG 22 2R7 1993 1
NRC QUESTION Tubes In your response, it was indicated that dented locations (specifically dented support plate locations) are susceptible to circumferential cracking and that augmented rotating pancake coil examinations have been performed for detecting circumferential cracking at dented tube support plates.
Specify the inspections performed during the previous Salem Units 1 and 2 steam generator tube inspection outages.
It was indicated that dents greater than 5.0 volts will be inspected with an Appendix H qualified probe (Cecco 5 or plus point) during the next steam generator tube inspections.
Provide the procedures used for sizing the dents.
If the procedure is identical to the procedure for the voltage-based repair criteria, a detailed description is not necessary.
Future inspection plans for dented (> 5V) intersections concentrate at the lowest hot-leg tube support plates.
A large dent at an upper tube support plate may be more significant in terms of corrosion susceptibility as a result of higher stresses than at a small dent at a lower tube support plate even though the temperature is lower at the upper tube support plate.
Given this, discuss the basis for the proposed sample strategy given that cracking depends on many factors including temperature and stress levels.
The inspection plan for dented locations differ from Units 1 and
- 2.
Discuss the reason for this difference.
PSE&G RESPONSE The following inspections were performed during the previous Unit 1 and 2 outage~ using a rotating pancake coil (RPC) probe at dented tube support plate intersections:
Page 2 of 6
LR-:N95172 ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 OUTAGE lRlO {Spring 1992)
SG No.
11 12 13 14 OUTAGE lRll SG No.
11 12 13 14 OUTAGE 2R7
. sG No.
22 24
{Fall (Spring No. of Dented Intersections Insp.
488 (Up to 5th support plate) 530 (Up to 4th support plate) 533 (Up to 5th support plate) 516 (Up to 4th support plate) 1993)
No. of Dented Intersections Insp.
133 (Up to 5th support plate) 155 (Up to 4th support plate) 122 (Up to 5th support plate) 170 (Up to 5th support plate) 1993)
No. of Dented Intersections Insp
- 65 (Up to 7th support plate) 70 (Up to 7th support plate)
OUTAGE 2R8 (Fall 1994)
SG No.
21 22 23 24 No. of Dented Intersections Insp.
159 (Up to 6th support plate) 151 (Up to 7th support plate) 156 (Up to 5th support plate) 175 (Up to 7th support plate)
As stated in PSE&G's response to GL 95-03, no tubes have been plugged due to the detection of circumferential cracking in the tube support plate region.
However, five (5) tubes with axial indications were identified during lRll and were plugged.
PSE&G Site Specific Data Analysis Guidelines, SC.RA-TS.ZZ-OOOl(Q), is used for sizing dents at tube support plate intersections.
The voltage scale for the 20% ASME defect is set to 4 volts using a channel setting of 400 KHz Differential.
The voltage scale is saved and stored to all channels~
Dents are measured with a channel setting of 400/100 KHz Differential.
Dents greater than or equal to 5 volts peak-to-peak are recorded.
Page 3 of 6
LR-:N95172 ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 The bases for concentrating our inspections on lower tube support plate (TSP) intersections are: (1) the previous inspection results at Salem (i.e., five tubes with axial indications identified last outage (lRll) for Salem No. 1 only at hot leg intersections at or below the third TSP and no circumferential indications identified to date), and (2) the concentration of North Anna's axial and circumferential cracking at the lower three TSP intersections.
Expansion criteria for dented TSP intersections are discussed in Response to Question 4 below to ensure axial and circumferential cracking is bounded.
The difference in inspection plans between Salem Nos. 1 and 2 was also based on Salem No. 1 exhibiting axial indications at the first three TSP's.
To date, similar axial indications have not been found at Salem No. 2.
In the current Salem No. 1 outage, indications at non-dented TSP intersections have been identified.
After reviewing the results of the current (.1R12) Salem No. 1 inspections, which are in progress, PSE&G will re-evaluate the initial augmented inspection scope for Salem No. 2 at TSP intersections, and expand the initial scope as necessary.
The revised inspection scope for Salem No. 2 will be finalized after completion of the Salem No. 1 ins~ections.
- 4.
NRC QUESTION Please provide the expansion criteria to be used for a,11 locations susceptible to circumferential cracking.
PSE&G RESPONSE The areas susceptible to circumferential cracking are the Row 2 (small radius) U-bends, dented tube support plate intersections, and the hot leg tube expansion transitions.
The Salem steam generator tubes do not have sleeved joints.
The augmented inspections planned during the current Unit 1 and 2 outages for the identification of cracking are in addition to the inspections that are required to be completed in accordance with Technical Specifications (TS) 4.4.5 (Ul) and 4.4.6 (U2) using the bobbin coil probe.
The expansion criteria for the planned augmented inspections conservatively applies the existing TS sample expansion requirements per Table 4.4-2 for the specific areas where imperfections were previously identified.
Page 4 of 6
LR-;-N95172 ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 Expansion criteria for Row 2 small radius U-Bends require that if a pluggable indication is detected in the original sample population, the inspection program is expanded to cover 100% of the Row 2 U-Bends therefore satisfying Tech.
Spec. and EPRI bounding criteria.
The expansion criteria for dented tube support plate intersections is determined by the support plate elevation where the 20% random population is inspected.
If one (1) pluggable indication is detected in the 20% random population, the expansion criteria require a 100% inspection at that elevation of all > 5 volt dented intersections and a 20% random sample of > 5 volt dented intersections at the next higher tube support plate elevation. This expansion satisfies both Tech. Spec. and EPRI's recommendation for bounding.
The expansion criteria for WEXTEX transition area is governed by Tech. Spec. and WEXTEX Guidelines (WOG-WEX-92-06).
However, based on the scope of dented tube support plate intersection examinations, all WEXTEX transition areas were inspected during 1R12.
Therefore,.the expansion criteria did not apply.
The results of augmented inspections will be combined with inspection results using the bobbin coil to determine the Technical Specification category for each steam generator based on the total number of defective and/or degraded tubes identified.
S.
NRC QUESTION During the Maine Yankee outage in July/August 1994, several weaknesses were identified in their eddy current program as
'detailed in.NRC Information Notice 94-88, "Inservice Inspection Deficiencies Result in Severely Degraded Steam Generator Tubes".
In.Information Notice 94-88, the staff observed that several circumferential indications could be traced back to earlier inspections when the data was reanalyzed using terrain plots.
These terrain plots had not been generated as part of the original field analysis for these tubes.
For the rotating pancake coil (RPC) examinations performed at your plant at locations susceptible to circumferential cracking during the previous inspection (i.e., previous inspection per your Generic Letter 95-03 response), discuss the extent to which terrain plots were used to analyze the eddy current data.
If Page 5 of 6
LR-:N95172 ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
GENERIC LETTER 95-03 terrain plots were not routinely used at locations susceptible to circumferential cracking, discuss whether or not the RPC eddy current data has been reanalyzed using terrain mapping of the data.
If terrain plots were not routinely used during the outage and your data has not been reanalyzed with terrain mapping of the data, discuss your basis for not reanalyzing your previous data in light of the findings at Maine Yankee.
Discuss whether terrain plots will be used to analyze the RPC eddy current data at locations susceptible to circumferential cracking during the next steam generator tube inspection (i.e., the next inspection per your Generic Letter 95-03 response).
PSE&G RESPONSE Data Analyst Guidelines required terrain plots to be generated when analyzing MRPC Eddy Current Data for the past two outages on each Salem Unit.
These guidelines require terrain plots to be generated when analyzing MRPC data for the current outages, and terrain plots will be required for future outages.
For the 2R7 and lRlO outages, Data Analyst Procedure VSC.SS-IS.ZZ-0019(Q) was used in the analysis of the eddy current data.
This procedure required terrain plots for all MRPC data to be generated.
Starting with lRll, Site Specific Guidelines SC.RA-TS.ZZ-OOOl(Q) along with Data Analyst Procedure VSC.RA-IS.ZZ-0019 (Q) have been used.
These procedures also require terrain plots for evaluating MRPC data.
Page 6 of 6