ML20011D111
| ML20011D111 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/31/1989 |
| From: | Bates R, Lakner A VIKING SYSTEMS INTERNATIONAL |
| To: | NRC |
| Shared Package | |
| ML20011D112 | List: |
| References | |
| CON-NRC-03-87-028, CON-NRC-3-87-28 GL-88-01, GL-88-1, NUDOCS 8911090225 | |
| Download: ML20011D111 (32) | |
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i TECHNICAL EVALUATION REPORT ON RESPONSE FROM
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PHILADELPHIA ELECTRIC COMPANY f
M GENERIC LETTER 88-01 PERTAINING M THE LIMERICK GENERATING STATION, UNIT 1 Publishe( October,1989 i
prepared by Robert C. Bates Armand Lakner Viking Systems International i
2070 Wm. Pitt Way Pittsburgh, PA Prepared fort f
U.S. Nuclear Regulatory Commission Washington, D. C. 20555 under Contract No. NRC-03-87-028, Task Order 005 Ml/$9$M5 n
ABSTRACT i
This report contains an evaluation of the licensee (Philadelphia j
Electric) submittal for Limerick Generating Station, Unit I which was submitted in response to the NRC Generic Letter 88-01 in which Philadelphia Electric was requested to (1) Furnish their current plans relating to piping replacement ar.d other measures to mitigate IGSOC, inspection, repair, and leakage detection.
(2) Indicate whether they l
1 plan to follow the NRC Staff positions, or propose alternative measures.
Philadelphia Electric's plans are evaluated in Section 2 of this report 1
in terms of compliance to NRC Staff positions. An alternative position concerning an amendment to the Technical Specification on ISI is l
discussed in Section 3 of this report.
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- SUNNARY The Licensee Philadelphia Electric, submitted a response to the NRC Generic Letter 8S-01. Philadelphia Electric's response pertaining to the austenitic stainless steel piping in the Limerick Generating Station, Unit 1 (a BWR nuclear power plant) was evaluated in terms
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oft (1) Their previous and planned actions to mitigate IGSOC to provice assurance of continued long-term service.
(2) Their Inservice Inspection (ISI) Program. (3) Their Technical Specifications pertaining l
to ISI and their plans to ensure that leakage detection will be in conformance with the NRC Staff position.
(4) Their plans to notify the NRC of significant flaws identified (or changes in the condition c
of the velds previously known to be cracked) during inspection and evaluation of such flaws.
Philadelphia Electric endorses eight of the 13 NRC Staff positions which are outlined in Generic Letter 88-01. They did not indicate i
endorsement or rejection of five of the NRC Staff positions (i.e.,
clamping devices, weld ovarlays, stress improvement of cracked weldments, water chemistry, and part of the item on leakage detection).
They do use controlled water chemistry, but it is not clear whether HWC is used. They stated that their Technice.1 Specification (TS) on leakage detection conforms with the NRC Staff position, but they did not indicate any restrictions on the rate of increase in unidentified leakage.
In addition the TS differs on frequency of leakege monitoring.
Extensive programs of piping replacement hcve been conducted at Limerick 1 with the result that most welds (except in portions of the RWCU) are ICSCC Category A welds.
No specific plans for additional measures were presented except for continuation of controlled water chemistry.
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Philadelphia Electric stated that their ISI program for Limerick I will conform with the NRC Staff positions on schedule and on methods and personnel.
However, they declined to amend the TS on ISI.
- Rather, they plan to add the required statement to the ISI program.
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r CONTENTS ABSTRACT i
SUMMARY
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1.
INTRODUCTION 1
l 2.
EVALUATION OF RESPONSE TO GENERIC LETTER 88-01 2
2.1 Documents Evaluated 2
2.2 Review of Philadelphia Electric's Responses 3
to Staff Positions and Implementatbn of
'Ihose Positions l
2.3 Review of Classification of Welds, Previous 4
Mitigating Actions, and Previous Inspections 2.3.1 Current IGSCC Classifications 4
2.3.2 Composition of Materials 9
2.3.3 Recent Mitigating' Actions Reported in 9
Philadelphia Electric's Revised Submittal t
2.3.4 Previous Inspection Programs 10 2.3.5 Evaluation of Previous Mitigating Actions 10 and Inspections 2.4 Current Plans for Mitigating Actions 11 2.4.1 Summary of Plans 11 2.4.2 W'ater Chemistry Control 11 2.4.3 Stress Improvement and Additional Piping Replacement 12 2.4.4 Evaluation of Conformance to Staff Positions 13 and Recommendation 2.5 Plans for Future Inspections 13 2.5.1 Summary of Inspection Schedules 13 1
2.5.2 Personnel and Methods 14 2.5.3 Sample Expansion 14 e
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2.5.4 Plans for Uninspectable Welds 15 I
2.5.5 Evaluation and Recommendations 15 j
2.6 Changes in the Technical Specification Concerning ISI 16 2.7 Confirmation of Leak Detection in the 16 Technical Specification v
2.7.1 Adherence to Regulatory Guide 1.45 17 I
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2.7.2 Leakage Umits 17 1
2.7.3 Frequency of bakage Measurements 18 i
2.7.4 Description of Unidentified I.makage 18 2.7.5 Operability of Measurement Instruments 19 2.7.6 Evaluation and Recommendation 20 2.8 Plans for Notification of the NRC of Flaws 20 l
2.8.1 Philadelphia Electric's Position 20 j
2.8.2 Evaluation and Recommendation 21 t
3.
ALTERNATIVE POSITION 21 3.1 Alternative Position on ISI in the 21 Technical Specification 3.1.1 Philadelphia Electric's Position 21
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l 3.1.2 Evaluation and Recommendation 22 i
L 4.
CONCLUSIONS AND RECOMMENDATIONS 23 5.
REFERENCES 27
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- 1. INTRODUCTION Intergranular stress corrosion cracking (IGSOC) near voldr2nts in Boiling Water Reactor (BWR) piping has been occurring for almost 20 years.
l Substantial efforts in research and development have been sponsored by the BWR Owners Group for ICSCC Research, and the results of this program, along with other related work by vendors, consulting firms and confirmatory research sponsored by the NRC, have permitted the development of NRC Staff positions regarding the IGSOC problems. The technical basis for NRC Staff positions is detailed in Reference 1, and further background is provided in Reference 2.
The results of these research and development programs prompted the NRC to issue Generic Letter 88-01 (see Reference 3) requesting all i
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licensees of BWR's and holders of construction permits to (1) Furnish their current plana relating to piping replacement, inspection, repair, andeleakage detection.
(2) Indicate whether theys (a) Plan to follow the staff positions, or (b) Propose alternative measures.
Specifically, Generic Letter 88-01 stated that an acceptable licensee response would include the following items:
(1) Current plans regarding pipe replacement and/or other measures taken or to be taken to mitigate IGSCC and provide assurance of continued long-term piping integrity and reliability, f
(2) An inservice inspection (ISI) program to be implemented at the next refueling outage for austenitic stainless steel piping.
(3) A change to the Technical Specifications to include a statement I
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i in the section on ISI that the inservice inspection program for piping vill be in conformance with the NRC Staff positions on schedule, methods and personnel.
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(4) Confirmation of plans to ensure that the Technical Specification related to leakage detection will be in conformance with the
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NRC Staff position on leak detection.
i (5) Plans to notify the NRC, in accordance with 10CFR50.55a(o),
j of any flaws identified that do not meet IW-3500 criteria of Section II of the ASME Code for continued operation without evaluation, or a change found in the coadition of the welds previously known to be cracked, and an evaluation of the flaws f
for continued used operation and/or repair plans, j
This report contains a technical evaluation of the response which Philadelphia Electric (sometimes es11ed PE or PEco in this report) submitted in response to the NRC Generic Letter 88-01 pertaining to tb i
Limerick Generating Station, Unit 1 (hereafter called Limerick 1).
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- 2. EVALUATION OF RESPONSE 'ID GENERIC LETTER 88-01 i
This evaluation consisted of a review of the response to NRC Generic
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Letter 88-01 of January 25, 1988 by Philadelphia Electric pertaining i
to Limerick 1 to determine if their performance and plans are in conformance with the NRC Staff positions or'if proposed alternatives are acceptable. Proposed inspection schedules and amendments to the Technical Specification were included in the review.
2.1 Documents Evaluated
" Review was conducted on the information pertaining to Limerick 2
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1 provided by the Licensee in the following documents.
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(1)
" Response to Generic latter 88-01, 'NRC Position on ICSCC in BWR Austenitic Stainless Steel Piping' for Limerick Generating Station," Docket Nos. 50-352 and 50-353, Philadelphia Electric Company, 2301 Market Street, P.O.
Box 8699, Philadelphia, PA 19101, August 2, 1988.
i (2)
" Revised Response to Generic 1Atter 88-01, 'NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping' for Limerick Generating Station, Units 1 and 2." Docket Nos.
i 50-352 and 50-353. Philadelphia Electric Company, 2301 Market Street, P.O. Box 8699, Philadelphia, PA 19101, May 30, 1989.
1 Hereafter, in this report, these documents will be referred to as
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Philadelphia Electric Submittals No. 1 and No 2 respectively, and collectively as the Philadelphia Electric Submittals.
l 2.2 Review of Philadelphia Electric's Responses to Staff Positions and Implementation of Those Positions.
L Generic Letter 88-01 outlines 13 NRC Staff positions pertaining
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to (1) materials, (2) processes, (3) water chemistry, (4) weld overlay, (5) partial replacement, (6) stress improvement of cracked weldments, (7) clamping devices, (8) crack evaluation and repair criteria, (9) inspection methods and personnel, (10) inspection schedulee, (11) sample expansion, (12) leak detection, and (13) l l
reporting requirements. Generic Letter 88-01 states that the 1
licensee should indicate in their submittal whether they endorse these NRC Staff positions or propose alternative positions. The Philadelphia Electric Submittals did not specifically state acceptance or rejection of the 13 NRC Staff positions, but the 1
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i Philadelphia Electric positions on most of the 13 items were implied j
in discussions in the Philadelphia Electric Submittals. These positions are presented in Table 1.
Note that Philadelphia Electric indicated acceptance of eight of
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the thirteen NRC Staff positions.
In addition, Philadelphia Electric 4
indicated their positions on most aspects of the NRC Staff positions on leakage detection, but they omitted comments pertaining to the requirement for plant shut down when the increase of unidentified 1
leakage exceeds 2 gpa. No indication of endorsement / rejection was provided concerning any weld repair technique (Weld Overlay, Stress Improvement of Cracked Weldments, or Clamping Devices). Finally, j
l Philadelphia Electric applies water chemistry control, but it is I
not clear from the information supplied whether that water chemistry control includes the use of Hydrogen Water Chemistry.
i 2.3 Review of Classification of. Welds. Previous Mitinatina
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Actions, and Previous Inspections I
l 2.3.1 Current IGSCC Classifications 1
Table 2a provides a summary of the classifications of welds
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at Limerick 1 into the various IGSOC categories on a system-by-system basis as given in Philadelphia Electric Submittal No. 1.
Table 2b contains an updated summary based on information supplied in Philadelphia Electric Submittal No. 2.
Note that between the time that Philadelphia Electric Submittals Nos. I and 2 were prepared: (1) Two IGSCC Category G velds in the Recirculation system were reclassified to IGSCC Category A (based on verification that the materials are resistant).
(2) Five, welds in the Residual Heat Removal System were removed.
(3) Two IGSOC Category G welds in the Reactor Core Isolation Cooling system were inspected and 4
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Table 1 Summary of PE's Responses to Staff Positions PE Has/Will PE Accepts NRC Applied Consider for Staff Position Staff Position In Past Future Use_
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- 1. Materials yes yes yes
- 2. Processes yes(*)
yes(*)
yes(*)
- 3. Water Chemistry NI(b) gg(b) gg(b)
- 4. Weld Overlay NI no NI
- 5. Partial Replacement yes(*)
yes(*)
yes(*)
- 6. Stress Improvement of Cracked Weldsents NI no NI
- 7. Clasping Devices NI no NI
- 8. Crack Evaluation and Repair Criteria yes no yes
- 9. Inspection Method I
and Personnel yes yes
- 10. Inspection Schedule yes(c) y,,(c)
- 11. Sample Expansion yes yes t
- 12. leak Detection NI(d) y7(d) gg(d)
- 13. Reporting Requirements yes yes l
(a) Most piping / welds were originally constructed of corrosion resistant materials, some piping has been removed, and both partial replacement and SI are considered options for future sitigating action.
(b) Water chemistry control applied, but it is not clear whether it includes Hydrogen Water Chemistry.
(c) Neither previous nor planned inspection schedules were submitted, but PE stated that schedules would comply with NRC Staff position.
(d) No indication provided on PE's position concerning 2 gra increase in unidentified leakage, but PR indicated their positions on l
other leakage detection requirements.
NI Not indicated.
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,y Table 2a l
Summary of IGSCC Classification of Welds in Limerick 1 (per Philadelphia Electric Submittal No.1) j Number of Welds of Indicated IGSCC Catenory System A
B C
D E
F G
Totals Rectre.
237 0
0 0
0 0
2 239 RHR 86*
O O
O O
O O
86*
CS 26*
0 0
0 0
0 0
26*
RWCU-l 29 0
0 0
0 0
0 29 RWCU-2 0
0 0
0 0
0 195 195 i
RCIC 0
0 0
0 0
0 2
2 RPV-JPI O
O O
4 0
0 0
4 Totals 378 0
0 4
0 0
199 581 i
RPV Nozzle Number of Welds of Indicated IGSCC Catenory Number A
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D E
F G
Totals N1 0
0 0
2 0
0 0
2 N2 0
0 0
10 0
0 0
10 N5 0
0 0
,2 0
0 0
2 N8 0
0 0
2 0
0 0
2 N9 0
0 0*
1 0
0 0
1 N10 0
0 0
0 0
0 1
1 N11 2
0 0
0 0
0 0
2 l-N12 4
0 0
0 0
0 0
4 L
N16 4
0 0
0 0
0 0
4 N17 0
0 0
4 0
0 0
4 s
Totals 10 0
0 21 0
0 1
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Notes and Explanation of abbreviations:
Indicates that 4 safe-end to pipe welds in RHR at the LPCI inlet nozzle N17 and 2 safe-end to pipe welds in CS at the N5 inlet nozzle involve nickel alloy forgings.
Recire.
Reactor Recirculation RHR Residual Heat Removal CS Core Spray RWCU-1 Reactor Water Cleanup from RHR to outer containment isolation valve RWCU-2 Reactor Water Cleanup beyond outer containment isolation valve RCIC Reactor Core Isolation Cooling RPV-JPI Reactor Pressure Vessel - Jet Pump Instrumentation 6
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i Table 2b Summary of IGSCC Classification of Welds in Limerick 1 (per Philadelphia Electric Submittal No. 2)
Number of Welds of Indicated IGSCC Catenory System A
B C
D E
F G
Totals Recire.
239 0
0 0
0 0
0 239 RHR 81*
O O
O O
O O
81*
CS 26*
O O
O O
O O
26' RWCU-1 29 0
0 0
0 0
0 29 RWCU-2 0
0 0
0 0
0 195 195 RCIC 0
0 0
2 0
0 0
2 RPV-JPI 4
0 0
0 0
0 0
4 Totals 378 0
0 4
0 0
199 581 RPV Nozzle Number of Welds of Indicated IGSCC Catenory Number A
B C
D E
F
_fc Totals N1 0
0 0
2 0
0 0
2 N2 0
0 0
10 0
0 0
10 N5 0
0 0
,2 0
0 0
2 N8 0
0 0
2 0
0 0
2 N9 0
0 0*
1 0
0 0
1 N10 0
0 0
0 0
0 1
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N11 2
0 0
0 0
0 0
2 N12 4
0 0
0 0
0 0
4 N16 4
0 0
0 0
0 0
4 N17 0
0 0
4 0
0 0
4 Totals 10 0
0 21 0
0 1
32 Notes and Explanation of abbreviations:
Indicates that 4 safe-end to pipe welds in RHR at the LPCI inlet nozzle N17 and 2 safe-end to pipe welds in
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CS at the N5 inlet nozzle involve nickel alloy forgings, i
Recire. Reactor Recirculation RHR Residual Heat Removal CS Core Spray RWCU-1 Reactor Water Cleanup from RHR to outer containment isolation valve L
RWCU-2 Reactor Water Cleanup beyond outer containment isolation valve RCIC Reactor Core Isolation Cooling RPV-JPI Reactor Pressure Vessel - Jet Pump Instrumentation 7
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reclassified as IGSCC Category D.
(4) The four welds in the Jet Pump Instrumentation (two safe-end extension welds f
and two weal extension to seal' welds) were upgraded from
.IGSOC D to IGSCC Category A based on verification of material
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properties. No changes were reported in the nozzle welds.
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IGSOC classifications of the welds are also contained on l
a weld-by-weld basis in the Philadelphia Electric Submittals (not reproduced in this report), although a largo number of welds were excluded from the table (except for notations
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concerning their existence and their IGSOC classifications) including: (a) all of the RWCU welds outside of containment, (b) all of the nozzle to safe-end welds in N1, N2, N5, N8, N9, N10, Nil, N12, N16, N17, and (c) several safe-end to i
extension welds. The veld-by-weld listing of welds contain numerous seas welds. Most of the seas welds were not assigned IGSCC classifications (in' keeping with the scope of Generic Letter 88-01 which excludes longitudinal welds), but many seas welds were assigned IGSCC classifications and are
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included in the summary presented in Tables 2a and 2b. The reasons why some seam welds were excluded (while others were not) were not provided by Philadelphia Electric. An explanation was requested in a Request for Additional Information, but so far, an answer has not been received.
Note that'all of the 195 welds listed for the portion of the RWCU that is beyond the outer containment isolation valve are uninspected, non-resistant (IGS00 category G) welds.
l Almost all other welds (except for the nozzle welds) are i
IGSOC A welds, the exceptions being two IGSCC Category D welds in the Reactor Core Isolation Cooling system.
Note, also, that the Reactor Pressure Vessel nozzles contain a total of 32 welds classified as follows: 10 IGSCC Categcry 8
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A welds, 21 IGSOC Category D welds, and one IGSOC Category G weld.
2.3.2 Composition of Materials The large number of IGSCC Category A welds were so classified because these welds, according to the Philadelphia Electric
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Submittals, are resistant due to their chemical composition.
i Materials in IGSCC Category D and G welds are non-resistant.
l However, with the exceptions discussed in the following paragraph, neither the compositions nor the identities (material types or specifications) were provided in the Philadelphia Electric Submittals.
Some question exists about the classifications of six safe-end j
to nozzle welds (four in the Residual Hemt Removal system
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and two in the Core Spray system) which involved nickel alloy forgings, Philadelphia Electric classified these welds as IGSCC Category A welds. No explanation for these classifications was provided except that Generic Letter 88-01 allows evaluation on a case by case basis.
2.3.3 Recent Mitinatinn Actions Reported in Philadelphia Electric's Revised Submittal Philadelphia Electric Submittal No. 2 contains the following statement concerning piping removal that occurred between l
the time Philadelphia Electric Submittals No. I and No. 2 j
were prepared:
i "The RHR Head Spray piping inside primary containment on Unit I was removed during the second refueling outage.
Removal of this piping results in descriptive c.hanges to portions of our original response, and deletion of 9
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,e welds from the accompanying tables."
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2.3.4 Previous Inspection Proareas i
Philadelphia Electric Submittal No. I does not provide information concerning whether or not any inservice i
inspections have been performed at Limerick 1.
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Philadelphia Electric Submittal No. 2 provides the following information pertaining to two IGSCC Category D welds in the Reactor Core Isolation Cooling system:
"The two Category D welds are to a high carbon stainless steel flow element, and have been upgraded from IGSCC Category G based on UT examinations performed during the second refueling Outage."
t Information that was provided concerning preservice l
t inspections of the 21 IGSCC Category D RPV nozzle to safe-end t
welds includes the followings "These welds were examined during preservice inspections (PSI) using the most updated UT techniques available.
(ref.: procedure LIM-UT-3 vendor print 8031-N-246B-56)."
l "No cracks were reported during the PSI examinations."
3 "The Unit 1 ISI program requires certification in accordance with the EPRI program for IGSCC detection."
I 2.3.5 Evaluation of Previous Mitinatina Actions and Inspections Most of the welds at Limerick 1 are classified as IGSCC f
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.o Category A except in several of the RPV nozzles and in the RWCU piping that is outboard of the containment isolation valves. Although Philadelphia Electric stated that the materials in the IGSOC Category A welds are resistant, compositions were not provided except that some of the IGSCC Category A welds inycive nickel alloys. Thus, it is not j
possible to verify that the welds classified as IGSCC Category A welds do, in fact, contain resistant materials. Also it is not possible to judge the validity of the assignment of j
the IGSOC Category A classifications of welds in nickel alloy j
components. Most nickel alloy components, according to j
Generic Letter 88-01, should be considered as non-resistant
- alloys,
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Since all IGSCC Category D welds have been inspected (either during preservice or during inservice inspections, seceptance of the classifications of these welds is recommended.
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2.4 Current Plans for Mitigatina Actions j
L l-2.4.1 Summary of Plans t
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The only specific plan for future sitigating actions consists j
of water chemistry control. Options that are being considered are stress improvement and replacement of non-resistant welds.
1 These itens are discussed in the following sections, j
u 2.4.2 Water Chemistry Control Philadelphia Electric Submittal Submittal No. 2 contains the following statement concerning water chemistry control:
"The PECo BWR water chemistry control program is detailed 1
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in Rev. ) of Philadelphia Electric Company's NGAP-NPO-1 " Interim Nuclear Group Admistrative Procedure --
Chemistry Control Prograa," effective date August 22, 1988. The water chemistry control requirements in this program are in accordance with the BWR Owners Group and Electric Power Research Institute _(EPRI) Water Chemistry Guidelines, existing General Electric chemistry recommendations and INPO recommendations."
2.4.3 Stress Imorovement and Additional Picina Replacement Philadelphia Electric Submittal Submittal No. 2 states:
"... With only three exceptions, the materials used in the Limberick Generating Station are resistant due to their chemical composition. Additionally, all of the longitudinal seas welds in the resistant piping have l
been solution heat treated. The exceptions to the use of resistant mategial are Certain welds involving RPV safe-ends.
Two welds involving a flow element in the RCIC system.
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Unit 1 RWCU beyond the outer containment isolation valve."
"For the few welds at Limerick which are not IGSCC Category A, stress taprovement and replacement are options that remain open at this time. Reclassification of IGSCC categories resulting from remedial actions or acquisition of additional information will be incorporated in the Inservice Inspection Program to assure continued conformance to the staff positions on inspection 12 9
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schedules, methods and persennel, and sample expansion."
f 2.4.4 Evalitation
- I Conformance to Staff Positions and Recommendation Since aitigating efforts have beert previously performed at Limerick 1 in accordance with Generic Letter 88-01 with the i
result that Ec.t of the welds (other than the welds in the RWCU that are outboard of the containment irsolation valves) r are IGSCC Category A welds, acceptance of ths Philadelphia j
Electric's position is recommended, provided that inspections and leakage detection follows requirements outlined in Generic Letter 88-01. These items are discussed later in this report.
2.5 Plans for Future Inspections 2.5.1 Summary of Inspection Schedules Philadelphia Electric Submittal No. 2 states:
L "The Augmented ISI Plan requirements for the individual l-Limerick Unit I and 2 weldsents within the scope of this NRC Generic Letter are given as Appendices A and B of
-i this document for ISS 1 & 2 respectively. These l
requirements have been integrated with the inservice t
inspection activities performed during the Unit 1 second t
l-p refueling outage and will be integrated with the Unit l
1 & 2 Inservice Inspection Program to be implemented at future refueling outages. The information provided for each weld in the appendices includes the system, piping isometric, weld number, description, and the applicanle IGSCC Examination Category according to the requirements of Table 1 of NudEG 0313. Revision 2."
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"The inspections will be performed at frequencies which will be in conformance with the Staff Position on j
Inspection Schedules for the piping welds within.the E
scope of Generic Letter 88-01...."
j 2.5.2 Personnel and Methods L
oL Philadelphia Electric Submittal No. 2 states:
"PECo is committed to complying with the NRC Staff L
positions or inspection methods and personnel as delineated in NRC Generic latter 88-01. For ultrasonic testing (UT) of'UT inspectable ASME Class 1 and 2 welds, the IGSCC inspections will generally be performed in accordance with the requirements contained in the applicable edition and addenda of ASME Section II for the ASME class of weldment. For UT inspectable-ASME l-Class 3 and non-class welds, the requirements in Section II for Class 2 welds will apply."
"The adition and addenda of ASME Section II used for
-determining these requirements will be as dictated by paragraph (g) of 10CFR50.55a. The' personnel performing the IGSCC volumetric inspections will be qualified for such inspections by a formal program approved.by the NRC."
2.5.3 Sample Expansion Philadelphia Electric's position on Sample Expansion is in 1'
compliance with the NRC Staff position. Specifically, Philadelphia Electric Submittal No. 2 states:
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"If one or more Category A, B, or C welds are found to 14 t 9;S r.
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t 59 be cracked, or if additional cracks or significant crack growth is discovered in a Category E weld during the interval, e sample expansion plan will be invoked which will be in accordance with the NRC Staff position on-Sample. Expansion as delineated in Generic Letter 88-01."
2.5.4 Plans for Uninspectable Welds Philadelphia Electric Electric Submittal No. 2 states:
"The integrity of ASME Class 1, 2, and 3 welds that are not UT inspectable will be verified by the applicable p
L ASME Section XI pressure test program.... The Water Clean-up System outside of containment is the only system with significant portions within the scope of the Generic L,
Letter that are prese,ntly considered to be UT-uninspectable. Th'e integrity of Non-ASME welds that are not UT inspectable will be verified by pressure tests conducted in accordance with the requirements of Section II Article IWB, IWC, or IWD-5000."
2.5.5 Evaluation and Recommendations l'
, Philadelphia Electric did not supply act9al. inspection schedules. Such schedules were requested in an RAI, but as yet, no reply has been received as yet. Although the
-actual schedules are not available, Philadelphia Electric states that the ISI program will follow the requirements of Generic Imtter 88-01 and NUREG 0313, Revision 2 on inspection schedules, methods and personnel, and sample expansion. In addition, their position concerning pressure testing of inaccessible welds is in conformance with Generic Letter 88-01. Thus, acceptance of Philadelphia Electric's position concerning their ISI program is recommended.
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r 2.6 Channes in the Technical Specification Concernina ISI The Philadelphia Electric Submittal No. I states that a change to the Technical Specifications on ISI will be added in the next application for miscellaneous administrative changes, altnough a target date for the change was not disclosed. The proposed change j
will add the following statement to Section 4.0.5 of the Limerick l
1 Technical Specification:
- t "The Inservice Inspection (ISI) Program for piping identified-in the NRC Generic Letter 88-01 shall be performed in accordance t
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with the staff positions on schedule, methods and personnel, and sample expansion included in NRC Generic Letter 88-01.
Details for the implementation of these requirements are included as augmented inspection requirements in the ISI program" l
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Philadelphia Electric also-stated that a similar statement would be added by February 28, 1989 to the FSAR, Section 5.24 (for Class I components) and Section 6.6(for Class 2 and 3 components).
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Subsequently, however, Philadelphia Electric changed this position and presented an alternative to the NRC Staff position.
This new position is discussed in Section 3-of this report.
2.7 Confirmation of Leak Detection in the Technical Specification The Philadelphia Electric Submittal states that the existing Technical ~ Specifications are in conformance with the NRC Staff c
position on leakege so that a change to the Technical Specification is not required. A comparison of the NRC Staff positions with 16 s 48 = q
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-4m is not' required. A comparison of the NRC Staff positions with the positions of Philadelphia Electric is shown below. Note that some differences exist between the Philadelphia Electric position and that of-the NRC Staff.
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2.7.1 Adherence to Reaulatory Guide 1.45 Generic latter 88-01 states:
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" Leakage detection should be in conformance with Position.
1 C of Regulatory Guide'1.45, ' Reactor Coolant Pressure Boundary Leakage Detection Systems,' or as otherwise approved by the NRC."
i The Philadelphia Electric Submittal states:
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"The drywell floor drain sump and drywell equipment drain tank monitoring system is designed to meet the intent of Regulatory Guide 1.45 for quantifying leakage."
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2.7.2 Leakane Limits Generic Letter 88-01 statest.
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" Plant shutdown should be initiated for corrective action when (a) within any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period any leakage detection system indicates an increase of unidentified leakage in= excess of 2 spe or 'its equivalent, or (b)-the total unidentified leakage attains a rate of 5 gpa or equivalent."
The Philadelphia Electric Submittal states:
"The Technical Specifications require that Reactor Coolant 17
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- e unit shall be in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in1 cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
"The Technical Specifications require that total Reactor-Coolant System leakage be limited to 30'gpm or the unit shall be in hot shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
i Note that the Philadelphia Electric Submittal does not address the requirement pertaining to an increase of unidentified leakage in excess of 2 gpa.
2.7.3 Frequency of Leakane Measurements l-Generic Letter 88-01 states:
" Leakage should be monitored (or determined from flow J
measurements if flow is continuously monitored)'at approximately four hour intervals or less.
L The Philadelphia Electric Submittal states:
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"The Technical Specifications require that drywell floor' l.
drain susp and drywell equipment drain tank flow rate are monitored at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
2.7.4 Description of Unidentified Leakane Generic Letter 88-01 states
" Unidentified leakage should include all leakage other than (a) leakage into closed systems or (b) leakage into i
the containment atmosphere from sources that are both specifically located and known either not to interfere L
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I with' operations _of monitoring systems or not to-be from a throughwall crack.
The Philadelphia Electric Submittal does not address this portion of the NRC Staff position.
2.7.5 Operability of Measurement Instruments Generic Letter 88-01 states:
"For plants operating with any IGSCC Category D, E, F, or G welds, at least one of the leakage measurement instruments associated with each sump shall be operable, and the outage time for inoperable instruments shall be limited to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or immediately initiate an orderly shutdown.
The Philadelphia Electric Submittal states:
"The Technical Specifications require that drywell floor drain sump and drywell equipment drain tank flow monitoring system are required to be operable or the unit will be in. hot-shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."'
"In addition, reactor coolant leakage.is detected by the primary containment atmosphere gaseous radioactivity monitoring system, the drywell unit coolers condensate-drain flow monitoring system and the primary containment-
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pressure and temperature monitoring systems. These-systems are also addressed in the Technical Specifications 19
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'2.7.6 Evaluation and Recommendation.
'Although Philadelphia Electric claimed that no change in the Technical Specifications on leakage detection is needed, some differences between the Limerick Technical Specifications and the NRC Staff position clearly exist. Specifically, Philadelphia Electric Subm'ittal does not address the requirement pertaining to an increase of unidentified leakage in excess of 2 gpa or the definition-(or description) of unidentified leakage. In addition. Generic Letter 88 requires monitoring of leakage at intervals of approximately-every four-hours or less while the Limerick Technical f
Specification requires monitoring at 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> intervals. Thus o
it is recommended that these portions of the Philadelphia Electric position on leakage should be rejected. Acceptance of the other portions of their position (which are in compliance with Generic Letter 88-01) is recommended.
Philadelphia Electric'should amend their Technical l'
Specification to include requirements for monitoring leakage at four hour intervals or less and to include requirements for plant shutdown when any leakage detection system indicates an increase in the rate of unidentified leakage in excess of;2 gpa or its equivalent as required by Generic latter 88-01.
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2.8 Plans for Notification of the NRC of Flaws L
2.8.1 Philadelphia Electric's Position Philadelphia Electric plans to adopt the NRC Staff position on notification. If any flaws are identified which do not meet the referenced criteria for continued operation, the NRC will be duly notified of the disposition of the affected 20
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flaws,-and NRC approval of the disposition for.each flaw exceeding-the criteria will be obtained before operation is resumed.
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Pertaining to evaluation of flaws: Flaws exceeding the
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acceptance criteria of IWB-3500 of ASME Section II will be either repaired, replaced, or evaluated. Repairs or replacements'will be documented in the Owners Report for Repairs and Replacements-as required-by ASME Section II.
Evaluations of flaws for continued operation will be performed 1
in accordance with the requirements of NUREG 0313. Revision 2 in conjunction with the criteria in IWB-3600.
- 0 2.8.2 Evaluatien and Recommendation i
l Since Philadelphia Electric plans to comply with the NRC Staff position, it is, recommended that' the plans for reporting of flaws and evaluation of flaws should be accepted.
- 3. ALTERNATIVE POSITION 3.1 Alternative Position on ISI in the Technical Specification-3.1.1 Philadelphia' Electric's Position As mentioned in Section 2.6 of this report, Philadelphia Electric initially accepted the NRC Staff position which requires an amendment to the Technical Specification on ISI stating that the ISI program will comply with the NRC Staff-position on inspection schedules, inspection methods and "E
personnel, andLsample expansion. Later, Philadelphia Electric changed their: position as stated in the following quote from Philadelphia Electric Submittal No. 2:
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" Inserting the recommended statement into Section 4.0.5 j
of the Limerick Technical Specifications, which contains l.
surveillance requirements, is not consistent with the
' philosophy of the Technical Specifications Improvement Program which encourages tha relocation of various
. specifications to other licensee controlled documents.
As stated in the-response to Item 2 of the Generic Letter, l
the staff positions on IGSCC will be incorporated into K.
the ISI Program. Documentation in the ISI Program, i
coupled with the FSAR statement described below, satisfies j
s the commitment for' documenting conformance to the steff positions on IGSCC."
"The ISI program for Limerick is described in the FSAR.
A revision has been made to the FSAR, Section 5.2.4,.
(for Class 1 components) and Section 6.6 (for Class 2-
& 3 components) re,f1'cting the following-inteatt e
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'The Inservice Insp(ction'(ISI) Program for weldsents in piping identified in accordance with the criteria L
of NRC Generic Letter 88-01_shall be performed in accordance with the NRC staff positions addressed in this Generic Letter. Details for schedule, c,
methods, personnel, and sample' expansion are included as augmented inspection requirements in.the ISI program.'"
3.1.2 Evaluation and Recommendation The NRC Staff, in formulating Generic Letter 88-01, recognized that Inservice Inspection and Testing Sections may be removed from the Technical Specifications in the future in line with the. Technical Specifications Improvement programs. Even so, the NRC Staff requires that this change be made at this 22
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- time, in addition, including a' statement In the ISI Plan would not carry the same weight as including a statement in the Technical l
Specification. Thus, rejection of the licensee's position is
.recorrended, and Philadelphia Electric should make the requested change in the Technical Specification on 151.
- 4. C0tlCLUSIONS AfiD RECOMMENDATIONS Philadelphia Electric endorsed eight of the thirteen NRC Staff positions as delineated in Generic Letter 88 01 (i.e., those pertaining to i
materialt, processes, partial replacement, crack evaluation and repair criteria, inspection nethods and personnel, inspection schedule, sample expansion, leakage and reporting requirements).
Concering processes, Philadelphia has applied solution treating but they have not applied stress; improvement or heat sink welding. They did not provide any indication of acceptance or rejection of four of the NRC Staff positions (i.e., those pertaining to hydrogen water chemistry, weld overlay, stress improvement of cracked weldmerrts, clamping devices, and portions of the item on leakage' detection). Concerning water chemistry, L
they indicated that they use controlled water chemistry, but they do not include'information concerning whether or not it involves hydrogen E
water chemistry.
Mos't of the welds at Limerick 1 that are covered in the scope of Generic l-Letter 88-01 are IGSCC' Category A welds. The-large number of IGSCC Category A welds is the result of extensive piping replacement programs-conducted at Limerick 1.
Notable exceptions are RWCU welds that are outboard of the isolation valves. All'of the welds in that portion of the RWCU contain non-resistant material, have not been inspected.
and are classified as IGSCC Category G welds. Other exceptions are contained in Reactor Pressure Vessel nozzles which contein-22 non-resistent welds (21 10 SCC Category D and one IGSCC Category G) 23
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-q in'a'ddition to 10 IGSCC Category A we16s.
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!Neither the piping and weld metal compositions nor the material identities were provided by Philadelphia Electric to verify their claim that the IGSCC Category A welds contain resistant (conformine) materials.
In addition some question exists about the validity of the IGSCC Category A classifications of six safe-end to nozzle welds.
These welds contain nickel alloys (the specific alloys were not identified), and they were classified as IGSCC Category A by Philadelphia Electric without explanation except for stating that Ceneric Letter 88-01 allows evaluation on a case t'y case basis.
Normally, according to Generic Letter 88-01, welds involving most nickel alloys are considered to be non-resistant.
No specific plans for additional mitigating actions were presented by Philadelphia-Electric except for continued water chemistry control, l
although they stated that stress improve' ment and additional piping replacement remain options.
Philadelphia Electric agreed to comply with the NRC Staff positions concerning inspection schedules, inspection methods and personnel, sample expansion, and reporting requirements.. Philadelphia ~ Electric submitted a list of' welds that fall within the scope of Generic Letter 88-01. However, they did not submit actual inspection schedules.
Philadelphia Electric initially agreed to change the Technical Specification concerning ISI, to-include a statement that the ISI program will conform with the NRC~ Staff Position on inspection schedules, methods and personnel, and sample expansion. They later changed that position and stated that such a statement will be included in the documentation for the ISI program rather than in the Technical ir Specification. Such an approach is specifically rejected in Generic letter 88-01.
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'c Philadelphia Electric stated that there is no need to change the Technical _ Specification on leakage detection because it already conforms with the NRC Staff position. However, an item by item review of information provided in'the Philadelphia Electric Submittals shows that one significant item is missing, i.e. a requirement for plant shut down when the rate of increase of unidentified leakage reaches 2 gpm. In addition Philadelphia Electric requires monitoring leakage at approximately at twelve hour intervals rather than four hour intervals or less.
As a result of this technical evaluation, the following recommendations are made.
(1) Acceptance of Philadelphia Electric's statement that the IGSCC Category A welds (with the exception of certain welds containing nickel alloys) are based on a verification that those welds contain resistant (conforming ) materials. However, it is also recommended that Philadelphia Electric should provide explanations of the IGSCC Category A classifications assigned to welds containing nickel alloys.
(2) Acceptance of Philadelphia Electric's position concerning their ISI program including inspection schedules, methods and personnel, sample expansion, and pressure testing of uninspectable welds.
(3) Acceptance of Philadelphia Electric's position on reporting of flaws.
(4) Rejection of Philadelphia Electric's position on changing the Technical Specification concerning ISI. Philadelphia should add a statement to the Technical Specification stating that the ISI program will conform with the NRC Staff position on inspection schedules, methods and personnel, and sample 25
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aupansion as delineated in Generic Letter 88-01.
(5) Rejection of Philadelphia Electric's statements concerning its conformance with the NRC Staff position on_ leakage l
detection. If not'aiready.in the Technical Specification, 49 Philadelphia Electric should add requirements that plant shutdown should be initiated for inspection and corrective j
action when, within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or less, any leakage detection system indicates an increase in the rate of unidentifed leakage in excess of 2 spe or its equivalent.
I They should also add a requirement which conforms with the NRC' Staff position on frequency of leakage monitoring as delineated in Generic Letter 88-01.
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(6) Acceptance of the other portions of Philadelphia Electric's position concerning the Technical Specification on. leakage detection.
(7) Acceptance of the remaining portions of the Philadelphia Electric Submittal.
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- 5. REFERENCES 4
1.
" Technical report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping," NUREG 0313.- Revision
- 2. U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, January,1988.
2.
" Investigation and Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plants," NUREG 0531, U. S. Nuclear Regulatory Commission, February, 1979.
3.
"NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping,"'
Generic Letter 88-01, U.S. Nuclear Regulatory Commission, January J
25, 1988.
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