ML20064A478
| ML20064A478 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 02/28/1990 |
| From: | Bates R, Lakner A VIKING INDUSTRIES, INC. |
| To: | NRC |
| Shared Package | |
| ML20064A461 | List: |
| References | |
| CON-NRC-03-87-028, CON-NRC-3-87-28 GL-88-01, GL-88-1, NUDOCS 9009100061 | |
| Download: ML20064A478 (47) | |
Text
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i T1.CHNICAL EVALUATION REPORT ON l
j RESPONSE FROM CO:010WEALTil EDISON lg TO GENERIC LETTER 88-01 PERTAINING 70 THE QUAD CITIES STATION, UNIT 2 l
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i l-VIKING SYSTEMS INTERNATIONAL l
Johnstown, Ohio Pittsburgh, Pennsylvania Washington, D.C.
I ggM88ei 8888Pr
i TECilNICAL EVALUATION REPORT ON RESPONSE PROM COFNONVEALTil EDISON TO GENERIC LETTER 88-01 PERTAINING TO Tile QUAD CITIES STATION, UNIT 2 Published February. 1990
,repared by Robert C. Bates Armand Lakner Viking Systems International 2070 Wm. Pitt Way Pittsburgh, PA Prepared fort I"[fITT" U.S. Nuclear Regulatory Commission
,' ' -- - e u k',
Vashington, D. C.'20555 I ds/..
under Contract No. NRC-03-87-028, Task Order 005
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ABSTRACT This report contains an evaluation of the licensee (Commonwealth Edison) submittal for Quad Cit'.es Station, Unit 2 which was submitted in response to the NRC Generic Letter 88-01 in which Commonwealth Edison was requested tot (1) Furnish their current plans relating to piping replacement and other measurea to mitigate IGSCC, inspection, repair, and leakage detection.
(2) Indicate whether they plan to follow the Commonwealth NRC Staff positions, or propose alternative measures.
Edison's plans are evaluated in Section 2 of this report in terms of compliance to NRC Staff positions.
Section 3 contains evaluations of an alternative position concerning a change to the Technical Specification on ISI, alternatives to portions to the NRC Staff position on leakage detection, and an exception to the scope of Generic Letter 88-01.
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e SGMARY The Licensee, Commonwealth Edison, submitted a response to the NRC Generic Letter 88-01. Commonwealth Edison's response pertaining to the austenitic stainless steel piping in the Quad Cities Station Unit 2 (a BWR nuclear power plant) was evaluated in terms of: (1) Their previous and planned actions to mitigate IGSCC to provide assurance of continued long-term service.
(2) Their Inservice Inspectica (ISI)
Program.
(3) Their Technical Specifications pertaining to IST and their plans to ensure that leakage detection vill be in conformance with the NRC Staff position.
(4) Their plans to notify the.NRC of significant flaws identified (or changes in the condition of the welds previously known to be cracked) during inspection.
Commonwealth Edison endorses most of the 13 NRC Staff positions which are outlined in Generic Letter 88-01, but they applied provisions t.o their endorsements of the NRC Staff positions concerning materials (i.e., concerning IGSCC classifications of welds between castings) and on Crack Evaluation and Repair Criteria. They proposed alternative positions on portions of the NkC Staff position on leakage detection.
Extensive programs of piping replacement, solution heat treatment, internal cladding, and stress improvement, and weld overlay repairs have been conducted at Quad Cities 2, so most welds have received mitigating treatments. Future plans include additional piping replacement / removal and implementation of Hydrogen Water Chemistry.
Commonwealth Edison stated that their IGSCC ISI program conforms with the NRC Staff position on schedule, methods and personnel, and sample expansion, but one IGSCC Category G veld (which is accessible for ITT inspection) is not scheduled for inspection, and a portion of the RWCU has been excluded from the IGSCC program.
In addition, they declined to amend the Technical Specification on ISI to include a statement that the ISI program will conform with the NRC Staff position. Rather, they proposed to include the required statement in the ISI Program, 11 I
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CONTENTS ABSTRACT SUhthiARY I
1.
INTRODUCTION 2
EVALUATION OF RESPONSE TO GENERIC LETTER 88-01 2.
2 2.1 Documents Evaluated 3
2.2 Review of Commonwealth Edison's Responses to Staff Positions and implementation of Those Positions 4
2.3 Review of Classification of Welds, Previous hiitigating Actions, and Previous inspections 4
2.3.1 Current IGSCC Classifications II 2.3.2 Summary of hiaterials and hiitigating Treatments 13 2.3.3 IGSCC Resistant Welds (Conforming hinterials)
I4 2.3.4 Previous inspection Programs 18 2.3.5 Evaluation and Recommendations 19 2.4 Current Plans for hiitigating Actions 19 2.4.1 Commonwealth Edison's Position 19 2.4.2 Evaluation of Conformance to Staff Positions and Recommendations 20 2.5 Plans for Future Inspections 21 2.5.1 Summary of Inspection Schedule 23 2.5.2 Inaccessible Welds 24 2.5.3 hiethods and Personnel 24 2.5.4 Sample Expansion 24 2.5.5 Evaluation and Recommendation 25 2.6 Changes in the Technical Speci0 cation Concerning ISI 111
o 25 p.
Confirmation of Leak Detcetion in the Technical Specification 2.7 27 2.8 Plans for Notification of the NRC of Flaws 27 2.8.1 Commonwealth Edison's Position 27 2.8.2 Evaluation and Recommendation 27 3.
ALTERNATIVE POSITIONS AND EXCEPTIONS 27 Alternative Position Concerning ISI in the Technical Specification 3.1 27 3.1.1 Commonwealth Edison's Position 28 3.1.2 Evaluation and Recommendation 29 3.2 leakage Detection in the Tecnnical Specification 31 3.2.1 Conformance with Regulatory Guide 1.45 32 3.2.2 leakage Limits 33 3.2.3 Frequency of Leakage Monitoring 33 3.2.4 Definition of Unidentified Leakage 34 3.2.5 Operability of Monitoring Instruments 35 3.2.6 Evaluation and Recommendations 35 3.3 Welds Excluded from lOSCC Program 35 3.3.1 Scope of Gencric Letter 8S 01 36 3.3.2 Commonwealth Edison's Position 37 3.3.3 Evaluation and Recommendation 37 4.
CONCLUSIONS AND RECOMMENDATIONS 41 5.
REFERENCES 1
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- 1. INTRODUCTION Intergranular stress corrosion cracking (ICSCC) near weldments in Boiling Vater Reactor (BWR) piping has been occurring for almost 20 Substantial efforts in research and development have been years.
sponsored by the BWR Dwners Group for IGSCC 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 IGSCC 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 licensees of BWR's and holders of construction permits to (1) Furnish their current plans relating to piping replacement, inspection, repair, and leakage detection.
(2) Indicate whether they:
(a) Plan to follow the staff positions, or l
l (b) Propose alternative measures.
Specifically, Generic Letter 8S-01 stated that an acceptr. ole licensee response would include the following items:
1 (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.
(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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.l in the section on ISI that the inservice' inspection program for piping vill be in conformaice with the staff positions on schedule, methods and persennel, and sample expansion.
(4) Confirmation of plans to ensure that the Technical Specification related to leakage detection will be in conformance with'the Staff position on leak detection.
(5) Plans to notify the NRC, in accordance with 10CFR50.55a(o),
of any flaws identified that do not meet Ik'B-3500 criteria.
of Section XI of the ASME Code for continued operation without.
evaluation, or a change found in the condition of the welds previously known to be cracked, and an evaluation of the flaws for continued operation and/or repair plans.
This report contains a technical evaluation of the response which his report) submitted Commonwealth Edison (sometimes called CE in t in response to the NRC Generic Letter 88-01 pertaining to the Quad Cities Station, Unit 2 (hereafter called Quad Cities 2).
- 2. EVALUATION OF RESPONSE TO GENERIC LETTER 88-01 This evaluation consisted of a. review of the response to NRC Generic Letter 88-01 of January 25, 1988 by Commonwealth Edison pertaining to Quad Cities 2 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 Quad Cities j
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1 provided by the Licensee in the following documents.
i (1) "Dresden Station Units 2 and 3, Quad Cities Station Units 1 and 2. LaSalle County Station Units 1 and 2 (Response to) Generic Letter SB-01, Docket Nos. 50-237/249,254/265, 373/374, License DPR-35," Commonwealth Edison, One First National Plaza, Chicago, Illinois 60609, July 29,1988.
(2) " Quad Cities Station Units 1 and 2, (Response to) Request for Additional Information to Generic Letter 88-01, TAC Nos. 961543 and 69155, Docket Nos. 50-251/265," Commonwealth Edison, One First National Plaza, Chicago, Illinois 60609, July 21, 1989.
I (3) " Quad Cities Station Unit 2 Inspection Plans for Piping Susceptible to Intergranular Stress Corrosion Cracking (IGSCC)," NRC Docket No. 50-265," Commonwealth Edison, 72 West Adams Street, Chicago, Illinois 60609 November 7, 1989, i
these documents vill be referred to Hereafter, in this renort, as CE Submittels No. 1, No. 2, and No 3, respectively, and collectively as the CE Submittals.
2.2 Review of Commonwealth Edison's Responses to Staff Positions and Implementation of Those Positions.
Generic Letter 8B-01 outlines thirteen NRC Staff positions pertaining to (1) materials, (2) processes (3) water chemistry, (4) veld 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 schedules, (11) sample expansion (12) leak detection, 3
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and (13) reporting requirements. Generic Letter 88-01 states that the licensee should indicate in their submittal whether they endorse Table these NRC Staff positions or propose alternative positions.
1 of this report, which is based on a similar table in CE Submittal No. 2 and discussion in both CE Submittals, shows the CE position concerning the 13 NRC Staff positions.
Note that Commonwealth Edison endorses most of the 13 NRC Staff They proposed alternative positions to portions of positions.
the item on leakage detection'(discussed in Section 3.2). They also stated that they applied a provision on inspection schedules, but it actually applies to IGSCC classifications of welds between castings and is discusscd in Section 2.3.3.
Finally, they applied a provision to the item on Crack Evaluation and Repair Criterim (i.e., they plan to incorporate the favorable stress distribution for calculations for stress improved welds \\.
This provision is acceptable and will not be discussed e)-
le in this report.
2.3 Review of Classification of Welds. Previous Miticatinn Actions, and Previous Inspections 2.3.1 Current IGSCC Classifications Welds that are outboard of the isolation valves in the RWCU have been excluded from the Quad Cities 2 IGSCC program, r
Discussion of these welds is contained in Section 3.3 of this report, and the remainder of Sections 2.3 and 2.4 deals only with those welds that are inboard of the isolation valves.
Table 2a of this report, which was constructed from a similar table contained in CE Submittal No. 1, provides a summary of the number of welds at Quad Cities 2 in each of the various 4
.able 1 Summary of CE's Responses to Staff Positions CE Has/Will CE Accepts NRC Xpplied Consider for Staff Position Staff Position In Past Future Use yes(b) yes(*)
yes
- 1. Materials
- 2. Processes yes yes yes no yes
- 3. Vater Chemistry yes yes(b)
- 4. Weld Overlay yes yes yes(b)
- 5. Partial Replacement yes yes
- 6. Stress Improvement of 5D) no yes Cracked Veldments yes yes(b)
- 7. Clamping Devices yes yes yes(b)
- 8. Crack Evaluation and yes(c) no Repair Criteria
- 9. Inspection Method and Personnel yes yes yes yes(a) yes( )
no
- 10. Inspection Schedule
- 11. Sample Expansion yes no yes yes(d) no yes
- 12. Leak Detection yes(b) no
- 13. Reporting Requirements yes (a) Commonwealth Edison stated that they applied provisions to inspection schedules, but they were actus11y applied to materials (i.e., assignment of IGSCC classifications to velds between castings). See text for discussi)n.
(b) Commonwealth Edison will implement this it.em as necessary.
(c) Provisions applied. See text for discus', ion.
(d) Alternate proposal presented on portioas of NRC Staff position.
See text for discussion.
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Table 2a i
Summary of IGSCC Classification of Welds (From CE Submittal No. 1)
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Diameter' No. of Welds of Indicated IGSCC Catenory Syst m Inch A
B C
D E
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G fpqql a
Retirulation 0
19 0
9 2
0 32 Sutlets 28-2.
Noz-SE 28 2
0 0
0 0
0 0
2 lleader 22 8
0 10 2
2 0
.0 22 Risers 12 0
0 23 0
21 0-0 44 Noz-SE 12 10 0
0 0
0 0
0 10 Pypass 4
4 0
0 3
0 0
5 12 J
.20 0
0 2
5 2
0 9
18 a
LPCI 16 0
0 26 0.
0 0
0 26' Core Spray 10 4
0 21 0
0 0
0 25 Jet Pump Inst 12, 8, 4 0
0 0
4 0
0 6
10 b
RWCU, lid Sp Spare Noz 6
33 0
0 3
2 0
7 45 i
C RD 4
3-0 0
10 0
0 14 27 3
Totals 66 0
101 27 36 2
41 273 t
Notes:
- a. Includes one inaccessible weld.
- c. Includes ~one inaccessible weld on Hd. Sp.
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4 The IGSCC IGSCC categories on a system-by-system basis.
classifications of individual velds are not listed in CE Submittal No.1, but such a list is contained in CE Submitt.a1 No. 2, and that list was used to construct the summary
'Ihe format of this presented in Table 2b of this report.
table is patteined after that in Table 2a. Note that several differences exist between Tables 2a and 2b:
(1) The total number of welds listed in CE Submittal 4
No. 2 is one more than that listed in CE Submittal No. 1 (274 versus 273).
(2) The number of IGSCC Category A velds listed in CE Submitt al No. 2 is two less than that listed in CE Submittal No. 1 (64 versus 66).
(3) The number of IGSCC Category D welds listed in CE Submittal No. 2 is one more than that listed in CE Submittal No. 1 (28 versus 27).
J (4) The number of IGSCC Category E velds listed in CE Submittal No. 2 is five less than that listed in Ct Submittal No. 1 (31 versus 36).
(5) The number of IGSCC Category F velds listed in CE
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Submittal No. 2 is six more than that listed in CE Submittal No. 1 (8 versus 2).
(6) The number of IGSCC Category G velds listed in CE Submittal No. 2 is one more than that listed in CE Submittal No. 1 (42 versus 41).
CE Submittal No. 3 provided additional changes in the numbers of velds assigned to the various IGSCC categories.
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Table'2b Summary of IGSCC Classification of Welds (From CE Submittal No. 2)
No. of Welds of Indicated IGSCC Category Diameter system Inch A
B Recirulation Outlets oB 2
0 18 0
6 6
1 33 Noz-SE 28 2
0 0
0 0
0 0
2 Header 22 0
10 2
2 0
0 22 Risers 12 0
23 0
21 0
0 44 Noz-SE 12 1
0 0
0 0
0 0
10 0
0 4
0 0
3 11 Oypass SDC 20 0
0 2
4 0
10" 18 RHR d
LPCI 16 0
0 26 0
0 0
0 26 Core Spray 10 3
0 22' 0 0
0 0
25 Jet Pump Inst 12, 8, 4 0
0 0
4 0
0 6
10 b
RWCU, lid Sp Spare Noz 6
33 0
0 3
0 2
7 45 c
id Sp lid Yt.
4 2
0 0
11 0
0 15 28 64 0
101 28 31 8
42 274 Totals Notes:
- a. Includes one inaccessible veld.
- c. Includes one inaccessible veld in the lid. Sp.
- d. Two of the Residual 11 eat Removal welds (Weld Nos.10AD-F3 and 10 AD See text are listed as IGSCC Category G in the inspection tables.
for discussion,
- e. One of the Core Spray velds (Weld No.14B-SBR) is listed as IGSCC See text for discussion.
Category A in the inspection table.
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f a This submittal, contains an addit $onal table, similcr to that prov;ded in CE Submittal No. 1, showing the number of Table r
velds classified in the various IGSCC categories.
Table 2c of this report is constructed after that table.
2c also contains a suiamary of the number of welds of each ICSCC category that are expected to exist following planned piping removal programs.
Note that several differences exist between this Table 2c and Tables 2a and 2b (1) The total number of welds listed in CE Submittal No. 3 is the same as that in CE Submittal No. 2 but one more than that listed in CE Submittal No. 1 (274 versus 273).
(2) The number of IGSCC Category A welds listed in CE Submittal No. 3 is one less than that listed in CE Submittel No. I but one more than that listed in CE Submittal No. 2.
(3) The number of IGSCC Category C welds listed in CE Submittal No. 3 is one less than that listed in either CE Submittal No. 1 or CE Submittal No. 2.
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(4) The number of IGSCC Category D welds listed in CE Submittal No. 3 is one more than that listed in CE Submittal No. 2 and two more than that listed in CE Submittal No. 1.
(5) The number of IGSCC Category E welds listed in CE Subaittal No. 3 is the same as that listed in CE Submittal No. 2 but five less than that listed in CE Submittal No. 1.
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e Table 2c Summary of IGSCC Classihcation of Welds (From CE Subtittal No. 3)
Diameter No. of Welds of Indicated IGS_CC Category System Inch A
B C
D E
F G
Total Rectrulation Outlets
'B 2
0 18 0
6 6
0 32
- d 0
0 0
0 0
0 2
Noz-SE 8
0 10 2
2 0
0 22 Header 0
0 23 0
21 0
0 44 1
o 1
Bypass h
h d
L C1 6
0 26 Core Spray 10 4
0 21' 0 0
0 0
25 Jet Pump Inr,t 12, 8. 4 0
0 0
4 0
0 6
10 b
RWCV. Ud Sp Spala Noz 6
33 0
0 3
0 2
7 45 Hd Sp. Hd Yt.
C CRD 4
9 0
0 11 0
0 15 28 Current Totals 65 0
100-29 31 8
41 274 68 0
100 16 31 6
27 24S Expected Totals (d)
Notes:
- a. Includes one inaccessible veld,
- c. Includes one inaccessible veld in the Hd. Sp.
- d. Totals expected following planned piping removal project.
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l (6) The numw of ; "
Submitta' No.
'= t.sne as that listed in CE Submittal %.. put six more than that listed in CE Submittal No. 1.
(7) The number of IGSCC Category G welds listed in CE Submittal No. 3 is the same as that listed in CE Submittal No. 1 but one less than that listed in CE Submittal No. 2.
Commonwealth Edison did not explain the reasons for the differences noted above, but hereafter, in this report, the following assumptions are made:
(1) For purposes of discussion of mitigating actions and previous inspections, it is assumed that Table 2b is correct because this table is based on detailed (veld-by-veld) descriptions ahile Tables 2a and 2c only give summaries of IGSCC classifications.
(2) For purposes of discussion of future inspection plans, it is assumed that Table 2e is correct because this table provides a summary of the number of welds expected to exist at Quad Cities 2 following planned piping removal programs.
2.3.2 Summary of Materials and Miticatine Treatments CE Submittal No. 2 lists the justification for the IGSCC classification for each of the welds including materials used (base metal and weld metal) and mitigating treatments.
A summary is provided in Table 3 of this report.
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Note that 41 velds are classified as IGSCC Category A because they contain materials considered by Commonwealth Edison to be resistant to IGSCC. One of these (Weld No. 12S-S26R in the RWCU) was ovetlaid, although it did not contain a flaw. Note also that three of the IGSCC Category A welds were produced u,3ng heat sink' welding (HSW). The remaining 20 IGSCC A weldn enre either solution heat treated (SHT) or internally clad with corrosion resistant cladding (CRC).
Stress improvement, using both the Induction Heating Stress Improvement (IHSI) process and the Mechanical Stress Improvement Process (MSIP), was applied to 103 velds, 101 Table 3 Summary of Mitigating Treatments e.nd Materials (based on CE Submittal No. 2)
No. of No. of Welds
Indicated Treatment Caten Caten Material SHT CRC HSW IHSI MSIP 0.L.
A 64 41 8
12 3
1 50 51 2
C 101 D
28 2
31 E
31 1
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F 8
f G
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- For a discussion of the materials considered to be conforming materials, see Section 2.3.3.
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of which are classified as IGSCC Category C.
Two of the stress improved welds were subsequently overlayed and are l
classified as IGSCC Category E.
i Weld overlays were applied to a total of 36 welds including Two IGSCC the previously mentioned IGSCC Category A welds.
Category C welds were also overlaid, although these welds 4
did not contain flaws. Although it is not stated in the CE Submittals, it is assumed that the ISHI treatments in these two velds were applied after the overlay was applied.
Thirty-three of the overlays were applied to repair flaws including 31 IGSCC Category E welds and 2 IGSCC Category F velds.
i Five welds contain unrepaired flaws, and a metallurgical These six welds are plug was taken from another veld.
classified as IGSCC Category F.
2.3.3 IGSCC Resistant Welds (Conforminn Materials)
Welds are considered by Commonwealt' Edison to be resistant
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1 to IGSCC and are classified as IGSCC Category A if they contain any of the following combinations of materials:
Base Metal Veld Metal Base Metal S.S. Pipe Conforming S.S. Pipe S.S. Pipe Conforming S.S. Casting C.S. Pipe Conforming S.S. Casting C.S. Pipe Non-Conforming S.S. Casting S.S. Casting Non-Conformit.g S.S. Casting where:
(1) S.S. pipe is Type 304L stainless steel.
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(2) C.S. pipe is carbon steel.
(3) Castings are stainless steel which contain > 0.035% carbon.
(4) Conforming veld metal is either: Type 308L stainless steel or Type 309L stainless steel.
(5) Non-conforming veld metal is stainless steel vhich contains > 0.035% carbon.
Note that castings and some veld metal (that used for velds which join two casting or some of the velds between carbon steel pipe and castings) contain carbon contents > 0.035%.
Commonwealth Edison's justification for classifying these velds as IGSCC Category A is contained in CE Submittal No.
2 which states:
" Welds joining castings with carbon content higher than 0.035%, such as cast pump body to cast elbow, are included i
in Category A.
The Staff Position on inspection schedules states that ' welds joining such castings (in the form of pump and valve bodies) to piping have been relatively free of 1GSCC. This may be attributable to a favorable l
stress distribution.'
This good service experience includes both cast and weld material with carbon content higher than 0.035"..
Therefore, it is logical to extend i
the Staff Position, which places high carbon cast material joined to resistant material in Category A, to also include cast material joined to cast material in Category A."
2.3.4 Previous Inspection Pronrams_
l CE Submittal No. 2 contains a list of velds that were inspected during Refueling Outages 8 and 9 (01/86 through Those 03/86 and 09/87 through 11/87, respectively).
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in pections are summarized in Table 4 of this report (which I
shows the number of welds of each of the various IGSCC categories that were inspected during those outages) and in the following paragraphs. It is presumed (but not actually stated in the CE Submittals) that those inspections were performed per KUREG 0313, Revision 2 (using methods and personnel qualified under the NRC/EPRI/BWROG coordination li (1) as indicated h3 plan as upgraded in September, 1985) because:
in Table 1, the NRC Staff position concerning inspection methods and personnel has been previously applied, and (2) these inspections occurred after September, 1985, the date of upgrading the NRC/EPRI/ Coordination plan, and (3) post-SI inspections were performed by EPRI personnel (according to the detailed list of welds in CE Submittal No. 2).
ICSCC Category A Welds: Twenty-one of these velds (33%)
were inspected during Refueli ng Outage No. 8. Refueling Outage No, 9, or both refueling outages (eight of these No flaws welds were inspected during both outages).
were found, h
J ICSCC Category C Welds: Ninety, en of the 101 IGSCC
.ed at least once during Category C welds were inspr Fift were inspected Refueling Outage Nos. 8 an' n u. car whether during both of those outag.-
eatment some of those inspections ae
,p;9vement inspections required folle i ealth L'ison stated Lo -.
treatments, but in any event, that all of the IGSCC Category C w..ds receive' post-SI Two of these were performed in 15 34.
The inspections.
other 99 were performed by EPRI p lonnel, although the The dates of these inspections were not disclosed.
inspection list in CE Submittal No. 2 states that one IGSCC Category C weld (Weld No. 02LeF2) contains a flaw; 15
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q Table 4 Summary of Inspection Schedules for Quad Cities 2 (based on CE Submittal No. 2)
-No. Inspected / Scheduled
,i No. of
_During Indicated R.O.
IGSCC Welds Past Future Required by Caten.
Categ.
08 09
_10 11_
,_yynericLetter88-01 A(a) 64 11 18 2
1 25% every 10 years (et Icast 12% in 6 years) 50% every 10 years (at B
0 least 25% in 6 years)
C 101 57 96 100 0
All within the next two refueling cycles, then all every 10 years (at 50 % in 6 years)
D(")
28 16 14 17 0
All every 2 refueling cycles E
31 31 25 31 0
50% next refueling cycle, then all every 2 refueling cycles F
8 6
8 8
0 All every refueling outage G(b) 42 0
0 25 C
All next refueling cycle (a) Three IGSCC Category A weld and 11 IGSCC Category D welds are scheduled to be removed during piping removal programs.
(b) Five IGSCC Category G welds are inaccessible for inspection.
Fifteen IGSCC Category G welds (three inaccessible and 12 i
accessible) are scheduled to be removed.
Dates of refueling outages are:
R.O.#
Date R.O.# Beginning Date OS 10/86-12/86 10 02/90 09 03/88-05/88 11 Not disclosed 16
4 11 W :;.-
-; y.
however, that statement must be in error because that' j
weld was. inspected during both Refueling Outages Nos.
l 8 and 9.with no flaws reported during those inspections.
IGSCC Catenory D Welds: All except one of these welds 4
(Weld No. 10HS-F12 in the Head Spray) were inspected
-g at least once during Refueling Outage Nos. 8 and 9.
Three of the welds were inspected during each of the e
L Commonwealth Edison stated that all IGSCC outages.
Category D welds have been inspected, so Weld No. 10HS-F12 i
must have been inspected during an earlier refueling No flaws were reported in any of these welds..
outage.
IGSCC Catercry E Velds: All 31 of the velds which are currently classified as 1GSCC Category E were repaired with veld overlays. Fifteen of those overlays were l
All 31 of the applied prior to Refueling Outage No. 8.
welds currently classified as IGSCC Category E were-inspected during Refueling Outage No. 8 as a result of which seven weld overlays were applied to previously L
uncracked welds. Twenty-five of the velds currently classified as 1GSCC Category E were inspected during
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Refueling Outage No. 9 resulting in application of nine weld overlays to previously uncracked welds. Inspections-of overlayed welds revealed a flaw in only one overlay.
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That weld overlay'was repaired during Refueling Outage No. 8 and replaced during Refueling Outage No. 9.
L IGSCC Category F Welds: All of the welds that are l1 currently classified as IGSCC Category F were inspected l
during etther Refueling Outage No. 8 or Refueling Outage No. 9 c. Iuth. Two of these velds have been weld overlaid. The dates of application of those overlays were not provided, but CE Submittal No. 2 indicates that 17
= -,
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they were repaired during Refueling Outage No. 9.
metallurgical plug was taken from one of the other IGSCC i
{
No flawr vere found during inspection Category F welds.
Small flaws of that weld during Refueling Outage No. 9.
i were reported for the other five welds in this category,:
and these welds have not been repaired.
2.3.5 Evaluation and Recommendations n
As previously mentioned, discussion concerning mitigating actions is. based on the assumption that Table 2b is correct rather than either Table 2a or 2b',
Commonwealth Edison should reconcile the differences in the numbers listed in Tables 2a, 2b, r.nd 2c to the satisfaction of the NRC Staff.
As a result of extensive programs to mitigate IGSCC including pipin8 replacement, solution heat treating, internal cladding,.
heat sink welding, 64 of the 274 welds at Quad Cities are An additional 103 welds, 101 of which.
IGSCC Category A.
Extensive are classified as IGSCC C, were stress improved.
inspection programs have also been conducted in which about a third of the IGSCC Category A welds and all of the welds classified as Categories C,'D, E, and F (except for four s
IGSCC Category C welds) were inspected at least once during Weld overlays have'been the last two refueling outages.
applied to a total of 33 welds to repair flaws during those inspections, and five flawed welds have not been repaired.
The mitigating treatments and the assignment of IGSCC classifications have followed NRC Staff guidelines, so acceptance of the assignment of IGSCC classifications is recommended, with three possible exceptions. The possible l
exceptions are three welds classified as IGSCC Category C since the table in CE Submittal No. 2 that provides inspection 18
l l
plans lists two_of-these_ welds.as IGSCC Category G and one as'_IGSCC Category A.
It is assumed in this report that IGSCC Category C is correct for these welds, but Commonwealth Edison should correct these three errors in their IGSCC program.
2.4 Current Plans for Mitigating Action 2.4.1 Commonwealth Edison's Position CE Submittal No. I does not list any specific plans for future mitigating actions except that Hydrogen Water Chemistry will late 1988),
be implemented (scheduled time for operation:
weld overinvs will be used to reinforce welds that are found-to have flaw indications, and system replacement / removal Candidates for system removal were is being considered.
identified in CE Submittal No. I as the Residual Heat Removal /
Head Spray and Control Rod Drive Return Lines.
CE Submittal No. 2, in the list of inspection plans, identified 29 welds in the Control Rod Drive system, Head Spray system, and Reactor Water Cleanup system that are currently scheduled for removal. These welds are distributed Included among among the piping systems as shown in Table 5.
the welds that are scheduled to be removed are three inaccessible IGSCC Category G welds (one in the CRD system and two in the RWCU).
2.4.2 Evaluation of Conformance to Staff Positions and Recommendations Commonwealth Edison has followed the guidelines of Generic Letter 88-01 and NUREG 0313, Revision 2 with the extensive mitigating actions that have already been applied at Quad 19
4
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.c '
'e e-E l <.
Table 5
-I Welds at Quad Cities 2 Scheduled for Removal.
1 Number of Welds of Indicated IGSCC Category'to be Removed System Caten. A Caten. D Caten. G Totals Control Rod Drive' 1
3 4
8 Head Spray 1
8 9
18-l 1
RWCU 1
2 3
1 L
l Totals 3
11 15 29 l
1 l
l Cities 2.
Although 75 welds remain unmitigated (28 IGSCC
~
1 Category D welds, 5 IGSCC Category F welds, and 42 IGSCC Catagory G welds), 26 of these (plus three IGSCC Category A welds) are scheduled for removal or' replacement. In addition, liydrogen Water Chemistry, should further. reduce the possibility of IGSCC. Thus, acceptance of Commonwealth Edison's position is recommended.
l l
2.5 Plans for Future Inspections l
Commonwealth Edison stated that an augmented inspection program will be conducted at Quad Cities 2 beginning with Refueling Outage.
No. 10, scheduled for February 1990. Additional discussion of that program follows.
l-i l
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,y fi 2.5.1 Summary of Inspection Schedule CE Submittal No. I states that the inspection schedules for-Quad Cities 2 are being revised to reflect the requirements for inspection schedules as delineated in Generic Letter 88-01.
CE Submittal No. 2 contains weld-by-weld inspection plans for Refueling Outage 10 (scheduled for 09/89)-and Refueling Outage 11 (scheduled date'was not disclosed) which are summarized in Table 4 along with the past inspections previously discussed. Table 6, which is based on a similar table in CE Submittal No. 3, contains an updated inspection-In this table, only the weld. population that is expected plan.
to exist after planned piping removal / replacement program Both Tables 4 and 6 also contain the requirements is shown.
for inspection schedules as delineated in Generic Letter'8S-01 and NUREG 0313 Revision 2.
Commonwealth Edison, in presenting these schedules, also included the following statement in CE Submittal No. 2:
"It should be noted that future inspection schedules,
... may be subject to change. However, at all times, Quad Cities Unit 2 will continue to meet the inspection schedules of the IGSCC categories as presented in Generic Letter 88-01."
CE Submittal No. 3 contains a similar statement.
As previously mentioned, for purposes of discussion of planned inspections, the veld populations as given in CE Submittal No. 3 (upon which Table 6 is based) is taken to be correct even though it differs from CE Submittal'No. I and CE Submittal The reasons for this assumption is that CE Submittal' No. 2.
No. 3 is the most recent submittal, it contains a revisions in the number of planned inspections, and it gives expected 21
[
,b I
f, to CE Submittal No. 2, a heat transfer analysis is planned to determine if its operating temperature may be < 200'F.
Plans for acoustic emission'were apparently abandoned because it was not mentioned in CE Submittal No. 2.
2.5.3 Methods and Personnel The augmented inspection program will be conducted using methods and personnel in conformance with the NRC Staff positions as delineated in Generic Letter 88-01 and NUREG 0313, revision 2.
2.5.4 Sample' Expansion CE Submittal No. I states that the Sample Expansion in the augmented inspection program will conform to the NRC Staff position as delineated in Generic Letter 88-01.
2.5.5 Evaluation and Recommendations The inspection schedules planned for accessible welds at Quad.
Cities 2 satisfy the requirements of Generic Letter 88-01 Plans should with the exception of one IGSCC Category G weld.
be amended to include that veld, otherwise acceptance of Commonwealth Edison's inspection plans for Quad' Cities 2 is recommended. Concerning the two inaccessible IGSCC Category G welds that will remain after completion of the piping removal / replacement program: (1) Plans for one of the inaccessible welds (i.e., visual inspections) is acceptable.
(2) A plan to investigate acoustic emission for the other inaccessible weld was presented in CE Submittal No.1, but apparently that plan was abandoned because the only plan concerning this weld presented in CE Submittal No. 2 is to perform a heat transfer analysis to determine if the operating 24
b Table 6 Summary of Inspection Schedules for Quad Cities 2
-(based on CE Submittal No. 3) l f)
Number of IGSCC-Wolds in No of Inspections Required by.
'~Caten.
Caten.
Sch1d. for R.O. # 10 Generic Letter 88-01 A(b) 68 6
'25% every 10 years (at least 12% in 6 years)
~
50% every 10 years (at B
0
-least 25% in 6-years).
C 103 100 All within the next two refueling cycles, then
.all every.10 years (at 50 % in 6 years)
D 16 16 All every 2 refueling cycles E
31 31 50% next refueling cycle, then all every 2 refueling cycles F
6 6
All cvery refueling outage.
G(')
27 24 All next refueling cycle (a) Number of welds in cach IGSCC category is based on the est. mated weld population following implementation of planned piping removal / replacement program.
(b) Includes two IGSCC Category A welds in the RWCU that are inaccessible for inspec. tion.
(c) Includes two welds that are inaccessible for inspection (one in the RWCU and one in the SDC).
Scheduled date of Refueling Outage No. 10 is 02/90.
22
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[,;. -.
veld populations after_the expected piping removal / replacement:
program.
Note that planned inspections satisfy the inspection.
requirements (as delineated in Generic Letter 88-01) with the exception of those planned for IGSCC Category-G welds..
For these velds, only 24 of the 25' accessible welds are scheduled for inspect ion. Thus, one of the accessible welds is not scheduled.
2.5.2 Inaccessible Welds Quad Cities 2 contains five inaccessible welds which are
. described below along with plans concerning these welds <
Two velds located inside the containment penetration assembly on the RWCU suction line. Replacement of the section of piping containing these welds 'is planned.-
A branch pipe connection on the RWCU suction line which The is completely encased in a reinforcement saddle.
saddle strengthens the veld and reduces stress, but it precludes UT inspection. Visual inspection.through a
" weep hole" is planned.
A weld on the Residual Heat Removal / Head Spray line which is located at the floor of the refueling cavity within a water barrier and sleeve arrangement. Complete removal of the section of piping containing this weld is planned.
A weld located inside the containment penetration assembly on the Residual Heat Removal / Shutdown Cooling line.
According to CE Submittal No. 1, acoustic emission monitoring of this location is being considered. According 23
=
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Plans to ensure the integrity of
~ temperature is!< 200'F.
this weld should be formulated and pursued until it is confirmed whether it is or is not within the scope of Generic Letter 88-01 (i.e., whether or not its operating temperature-is greater than or less than 200'F).
Commonwealth Edison's positions concerning methods and personnel and concerning sample expansion follow NRC Staff guidelines, so acceptance of these positions is recommended.-
2.6 Channes in the Technical Specification Concerning ISI Commonwealth Edison proposed an alternative position to the NRC Staff position concerning a change to the Technical Specification.
This' alternative position is discussed in Section 3 of this report.
2.7 Confirmation of Leak Detection'in the Technical Specification Table 7 of this report, which was constructed from a similar table.
contained in CE Submittal No. 2, summarizes Commonwealth Edison's positions on the various requirements for leakage detection as delineated in Generic Letter 88-01. Note that Commonwealth Edison stated that portions of the Quad Cities 2 Technical Specification pertaining to leakage are in conformance with the NRC Staff position (or will be revised to be in conformance with the NRC Staff position), but they proposed alternative positions concerning other Thus, discussion of leakage detection is deferred to portions.
Section 3 of this report, " Alternative Positions and Exceptions."
25
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e Table 7-Licensee Positions on Leakage Detection Already TS will be Alternate (a)
Contained Changed Position Position in TS _
to Include Proposed yes
- 1. Conforms with Position C of J
- 2. Plant shutdown should be initiated when:
yes (a) 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, an_ increase is indicated in the rate of unidentified leakage in excess of 2 gpm, or V
,(b) the total unidentified leakage yes attains a rate of 5 gpm.
yes
- 3. Leakage monitored at four hour intervals or less.
f-
- 4. Unidentified leakage includes all except:
yes (a) leakage into closed systems.
1 or yes (b) leakage into the containment atmosphere from sources that are located, do not interfere with monitoring systems, or not from throughwall crack.
yes
- 5. Provisions for shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> due to inoperable measurement instruments in plants with Category D, E, F, or G welds.
(a) See text for discussions concerning alternate proposals.
26
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2.8. Plans forLNotification of 'the NRC of Flaws 2.8.1 Commonwealth Edison's Position CE Submittal No. I states that the NRC will be notified of flaws in accordance with the NRC Staff position as delineated in Generic Letter 88-01. Additionally, notification vill-be provided of the evaluation by the' Commonwealth Edison Engineering Department for the canditions for continued operation and/or the necesse.ry ccrrective action to be Notification will be made by the Consolidated Edison.
taken.
Nuclear Licensing Department to the appropriate NRR project manager.
2.8.2 Evaluation and Recommendation Acceptance of Commonwealth Edison's plan is recommended since it complies with the NRC Staff position.
- 3. ALTERNATIVE POSITIONS AND EXCEPTIONS 3.1 Alternative Position Concerning ISI in the
' Technical Specification 3.1.1 Commonwealth Edison's Position It is the position of Commonwealth Edison that it is not appropriate to change the Technicel Specifications to include-statements in the section on ISI that inservice inspection programs for piping will be in conformance with the NRC Staff positions on schedule, methods and personnel, and sample expansion. Rather, they state that it is more appropriate to pursue changes to the stations Inservice Inspection 27
93 mn r
. Programs to include statements indicating conformance to 4
Generic Letter 88-01. Their reasons are quoted below from CE Submittal No. 1.
"The amendment would unnecessarily clutter the technical specifications.with inic -a. tion not appropriate for immediate' operator reference."
"The amendment does not meet the screening criteria for determining which. regulatory requirements and operating restrictions should be retained in:the standard technical specifications and ultimately in the plant technical specifications, as given in the Interim Policy Statement on Technical Specification Improvements, 52FR3788, February 6, 1987."
"As the industry and the NRC gain more insight into the causes of, and methods for prevention of IGSCC, the Therefore, requirements in this area will be changing.
addition of a reference to the generic letter in the technical specifications would require that the technical specifications be updated as the requirements in this area evolve."
3.1.2 Evaluation and Recommendation Generic Letter 88-01 discloses that the Inservice Inspection and Testing Sections may be removed from the Technical Specifications and included in the Inservice Inspection Program in the future (as proposed by Commonwealth Edison).
Despite this consideration, the NRC Staff, specifically included a requirement in Generic Letter 88-01 to change the Technical Specification to include a statement that the section on ISI will conform with the NRC Staff position on L
28 l
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schedule, methods and personnel, and sample expansion. Thus rejection of the Commonwealth Edison position is recommended.
It is further recommended that Commonwealth Edison should amend the Technical Specification on ISI for Quad Cities 2 to include a statement that the ISI program will conform with the NRC Staff position as delineated in Generic Letter-88-01.
-i 3.2 Leakao_e Detection in the Technical Specification CE Submittal No. 1 states that certain exceptions concerning the hTC Staff position on leakage detection are needed to avoid unnecessary plant modifications or unnecessary restrictive operating conditions at Quad Cit as 2.
These exceptions, as stated in CE Submittal No. 1, are as follows:
(1) " Individual identified leakage is not flow-metcred, but all identified leakage is collected and conducted to a-separate collection system from unidentified leakage. Total identified leakage is monitored via the drywell equipment drain sump pump discharge flow totalizer meter."
(2) " Sump operability is defined by the station as the ability to measure reactor coolant leakage rather than strictly depending on the operability of a leakage measurement Since only one channel exists for unidentified instrument.
leakage monitoring, strict compliance with the staff positions will not occur."
(3) " Increase in unidentified leakage shall be 2 gpm over the The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average will preclude previous 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average.
shutdown due to variations in measured coolant leakage between 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> intervals."
29 4
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3'
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j In response to a Request for Additional Information (RAI) concerning
' alternate methods of measuring reactor coolant leakage rather than J
strictly depending on leakage measurement instrument, Commonwealth
. Edison replied in CE Submittal No. 2 as follows:
"The ability to measure reactor coolant leakage can be accomplished by using sump pump flow recorder, timing the duration of pump operation or monitoring the input into Red Waste."
"Each sump pump's flow rate is recorded in the main' control room on a chart recorder. By integrating the area ~under the pen trace over time, the total flow can be calculated. The e
accuracy of-this determination vill be less than 90%; however, j
the integration can be co-wrvatively performed to determine
- a. bounding value for a ge. '_'
"In a similar way, the duration of sump pump operation can be timed.
A flow rate can be multiplied by the elapsed time to determine flow. The flow rate.can be chosen to bound previous flow rates recorded on the control room recorder."
a
'"The sump pumps input into the Waste Collector Tank in the
'i Rad Waste system. By reading the tank level increase at the time of sump pump operation, the Icakage can be determined.
.Because the relative error of this method is greater than 20%,
this method could be used to substantiate the two methods previously described."
i Commonwealth Edison's response to the RAI (CE Submittal No. 2) also included information used to construct Table 6 of this report which shows that some of the requirements concerning leakage detection as delineated in Generic Letter 88-01 are currently contained in the Quad Cities 2 Technical Specifications, others 30
3,1 o
l-B will be incorporated into the Technical Specifications, and they proposed alternative positions (exceptions) concerning'others.
Additional discussion concerning leakage detection are contained in the following sections.
i.
3.2.1 Conformance with Regulatory Guide 1.45 Generic Letter 88-01 states:
" Leakage detection systems should be in conformance with Position C of Regulatory Guide 1.45 ' Reactor Coolant Pressure Boundary Leakage detection Systems,' or as otherwise previously approved by the NRC."
CE Submittal No. 2 contains the following statements:
'The sensitivity
" Reg. Guide 1.45 Position C.5 states:
and response time of each leakage detection system in regulatory position 3 above employ'ed for unidentified leakage should be adequate to detect a leakage rate, or its equivalent, of one gpm in less than one hour.
The discussion regarding this position further clarifies this point. It states in part 'all detector systems should respond to a one gpm, or its equivalent, leakage increase in one hour or less.'"
" Identified and unidentified leakages are measured by determining the amount of water pumped from the Drywell Equipment Drain Sump and Dryvell Floor Drain Sump from flow totalizers. The amount of water pumped divided by the time interval between pumpdowns equals the leakage Pumpdowns occur at four hour intervals by manual rate.
pump actuation. The other detection methods that fulfill regulatory position 3, airborne particulate radioactivity 31
10, s
- 4_
t k't
.' l '
monitoring and monitoring of airborne gaseous radioactivity, are also accomplished by manual actions."
"The leakage detection systems are not abic to detect' a one gpm leakage increase in one hour or less. However.
indirect indications such as primary containment 1
i temperature and pressure have short response times to Reactor Coolant Pressure Boundary leakage."
" Reg. Guide Position 6 states: 'The leakage detection systems should be capable of performing their functions following seiemic events that do not require plant a
shutdown. The airborne particulate radioactivity monitoring system should remain functional when subjected to the SSE.'"
"The piping system from the drywell sumps to RAD Waste is not seismically designed. The airborne particulate radioactivity monitor and the gaseous radioactivity monitor are seismically designed. The monitors are.part-of the High Radiation Sample System implemented to meet KUREG 737 item II.B.3."
3.2.2 Leakane Limits
'l Generic Letter 88-01 states:
l
" Plant shutdown should be initiated for inspection and corrective 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 /> 1
or less, any leakage detection system indicates an increase in rate of unidentified leakage in excess of 2 gpm or its equivalent, or when the total unidentified leakage attains a rate of 5 gpm or equivalent, whichever occurs first."
32
.a 2
}.
Note from Table 6.that the Quad Cities 2 Technical-Specification contains requirements that conform with the NRC Staff porition concerning the 5 gpm total unidentified leakage. However, both of the CE Submittals contain;the following statement:
"The increase in unidentified leakage shall be 2 gpm over the previous 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average will preclude unit shutdown due to variations in measured reactor coolant' leakage between 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> intervals."
3.2.3 Freauency-of Leakage Monitorinn Generic' Letter 88-01 state:::
"For sump level monitoring systems with fixed-measurement-interval methods, the level should be monitored at approximately 4-hour intervals or less."
Note from Table 6 that Commonwealth Edison proposes an alternative position on this item. CE Submittal No. 2 states the following:
" Leakage vill be monitored at approxir.ately four hour intervals; a small interval tolere.ce will avoid technical specification violations while still maintaining a conservative surveillance interval."
3.2.4 Definition of Unidentified Leakage Generic Letter 88-01 states:
" Unidentified leakage should include all leakage other thant (a) leakage into closed systems, such as pump seal 33
c 3a,
+
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e i
or valve packing. leaks that are captured, flow metered, and conducted to a sump or collection tank, or (b) leakage
.nto the containment atmosphere from sources that are both specifically located and known either not to interfere with the operations of unidentified leakage P
monitoring systems or not to be from a throughwall crack.
i in the piping within the reactor coolant pressure boundary."
t
'As indicated in Table 6, the Quad' Cities 2 Technical CE Submittal Specification conforms with this position.
t No I contains the following clarifying remark:
i
" Individual identified. leakage is not flow-meterrd, but-all identified leakage is collected and conducted to.
a separate collection. system from unidentified leakage.
Total identified leakage is monitored via the drywell equipment drain sump pump discharge flow totalizer meter."
3.2.5 Operability of Monitoring Instruments Generic Letter 88-01 states:
i "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, j
l and the outage time for inoperable instruments shall f
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
{
l shutdown."
i As indicated in Table 6, the Quad Cities 2 Technical Specification will be amended to include this requirement, i
L r
34 I
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l}
i 4
3.2.6 Evaluation and Recommendations Commonwealth Edison's position concerning compliance with Regulatory Guide 1.45 is dictated by limitations of plant facilities, so acceptance of this position is recommended.
1 Commonwealth Edison's positions concerning limits on the total unidentified leakage of 5 gpm, description (or 3
definition) of unidentified leakage, and operability of-i leakage monitoring instruments are in compliance (or vill be changed to be in compliance) with the NRC Staff positions.
)
L Thus, acceptance of these positions are recommended.
l J
Commonwealth Edison's position concerning frequency of leakage measurements is within the intent of the NRC Staff position, so acceptance of Commonwealth Edison's position on this item is recommended.
However, concerning the requirement for limiting the increase of the unidentified leakage _to 2 gpm over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period', Commonwealth Edison's proposal to use the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average is less restrictive than that requ' ired in Generic letter 88-01. Thus, rejection of this position Commonwealth Edison should amend the Quad is recommended.
Cities ' Technical Spe:Afication_to limit the increase of unidentified leakage to 2 gpm over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (rather than over the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average).
l 3.3 Welds Excluded from IGSCC Program 3.3.1 Scope of Generic Letter 88-01 Generic Letter 88-01 defines the extent of its applicability
,i as follows:
35
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"This Generic Letter applies to all-BWR piping made of austenitic stainless steel that is four inches or larger in nominal diameter and contains reactor coolant at a temperature above 200'F during power operation regardless of Code classification. It also applies to reactor vessel attachments and appurtenances such as jet pump instrumentation penetration assemblies and head spray and vent components."
3.3.2 Commonwealth Edison's Position _
In response to a question in a Request for Additional Information (RAI) concerning whether any welds within this scope of applicability had been omitted from CE Submittal No. 1, the following statement was provided in CE Submittal No. 2:
"The submittal in response to Generic Letter 88-01 for Quad Cities Unit 2 included all' ASME Code class l', 2, 3 piping welds made of austenitic stainless' steel that are four (04) inches or larger in nominal diameter and contain reactor coolant at a temperature above 200 degrees F during power operation."
"Non-ASME Code stainless steel piping welds were NOT included in the submittal because they were considered to be outside the defined scope of Generic Letter 88-
- 01. The phrase 'regardless of Code classification' used in Generic Letter 88-01 (on page 2) is interpreted to limit the scope of applicability to piping which has been classified as ASME Code Class 1,2, or 3 for Inservice Inspection. The stainless steel welds in the Reactor Water Clean-Up (RWCU) system downstream of the outboard isolation valve are NON-ASME Code and Non-safety related."
36 l
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3.3.3 Evaluation and Recommendation'-
Commonwealth Edison has incorrectly interpreted the scope of welds covered by Generic Letter 88-01. The phrase, "regardless of Code classification" means that neither code related nor non-code related welds should be excluded unless i
they are excluded by the size or temperature requirements.
Thus, rejection of Commonwealth Edison's position is It is further recommended that Commonwealth recommended.
Edison should revise their IGSCC program to include the RWCU welds that are downstream of the isolation valves that are 4 inches or larger in diameter and operate at temperatures i
above 200'F.
- 4. CONCLUSIONS AND RECOMMENDATIONS l
Concerning the thirteen NRC Staff positions as delineated in Generic
~
Commonwealth Edison endorses most of the thirteen NRC Letter 88-01:
Staff positions, but they applied provisions to the NRC Staff positions concerning materials (specifically, the IGSCC classifications of welds between castings and inspection schedules for those welds) and concerning crack evaluation and repair criteria (that a favorable stress distribution resulting from stress improvement would be incorporated in calculations for stress improvea welds).
In addition, Commonwealth Edison proposed alternatives to some of the provisions outlined in Generic Letter 88-01 pertaining to leakage detection.
Commonwealth Edison excluded certain welds from their IGSCC program.
Specifically, the portion of piping in the RWCU that is outboard of the isolation valves was omitted.
An incorrect interpretation of the scope of Generic Letter 88-01 (i.e., that the scope is restricted to code related piping) was the basis for that omission, i
37
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c Extensive programs of piping replacement / removal, heat sink welding, solution heat treating, internal cladding, application of stress
-~'
improvement (utilizing IHSI and MSIP), and repair of cracked welds (using veld overlays) have been conducted at Quad Cities 2 vith the result that most velds that are inboard of the isolation valves have I
Based on CE Submittal
-received some form of mitigating treatment.
No. 2,: seventy-five welds remain unmitigated, but 26 of these (plus 7
=
three IGSCC Category A welds) are scheduled for replacement or removal.
i
[
Other actions planned for mitigating IGSCC are the implementation of Hydrogen Vater Chemistry and replacement and/or repair of welds (using NRC Staff approved processes) as needed.
In the assignment of the IGSCC classifications to welds between castings and between castings and carbon steel piping, Commonwealth Edison interpreted the guidelines of Generic Letter 88-01 to apply to IGSCC Category A classifications to these welds even though they contain This interpretation is within the intent of the NRC
> 0.035% carbon.
In addition, Staff guidelines as delineated in Generic Letter 88-01.
- d the assignment of IGSCC classifications to other welds-followed the guidelines of Generic Letter 88-01.
y.
An Inservice Inspection program (ISI) has been developed for Quad Cities 2 which, according to the CE Submittals, follows the guidelines of inspection requirements of Generic Letter 88-01 pertaining to schedule, methods and personnel, sample expansion, reporting of flaws, and plans for inaccessible welds. According to a summary of ISI plans contained-in CE Submittal No. 3, the number of accessible welds in each IGSCC category except for IGSCC Category G that are scheduled for inspection However, one complies with the requirements of Generic Letter 88-01.
accessible IGSCC Category G welds is not scheduled as required by Generic Letter 88-01.
The austenitic stainless steel piping systems at Quad Cities 2 contain F
five IGSCC Category G welds that are inaccessible for (TT inspection.
f
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f Visual' Three of these velds are scheduled for replacenerit/ removal.
inspection for the fourth inaccessible veld is planned. No plan currently exists for the other except to perform a heat transfer analysis to determine if its operating temperature is < 200'F.
Previously, Commonwealth Edison stated (in CE Submittal No. 1) that acoustic' emission monitoring of this weld was being investigated.
Commonwealth Edison ~ declined to change the Technical Specification on ISI to include, as required by Generic Letter 88-01, a statement that the IGS program will follow the NRC Staff position on inspection Rather they.
schedules, methods and personnel, and sample expansion.
Such action proposed to include such a statement in the ISI Program.
was specifically rejected in Generic Letter 88-01.
The Quad Cities 2 Technical Specification contains (or will be changed to contain) the provisions recommended by the NRC Staff pertaining to limits on the total unidentified leakage of 5 gpm, descriptions (or definition) of unidentified leakage,and operability of leakage Commonwealth presented an alternate proposal monitoring instruments.
concerning frequency of leakage measurements (i.e., that they will This is actually monitor leakage at approximately.4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> intervals).
within the intent of the NRC Staff.
Commonwealth Edison proposed two other alternative positions-concerning (1) Concerning the NRC Staff position on limiting leakage detection:
any increase of unidentified leakage to 2 gpm during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period This or less, they proposed using the average over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.
is unacceptable because it is less restrictive than the NRC Staff (2) Deviations from strict compliance with some items in' position.
These Regulatory Guide 1.45 were proposed by Commonwealth Edison.
deviations are dictated by limitations of plant facilities.
As a result of this technical evaluation, the following recommendations are made.
39
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0 (1) Rejection of Commonwealth Edison's position which excludes velds in piping =in the portions of the RWCU that is outboard of the isolation valves.- Commonwealth Edison should revise the IGSCC program for Quad Cities 2 (including inspection i
schedules) to include this portion of piping.
(2) Commonwealth Edison should reconcile the differences in the y
numbers of welds assigned to each of the IGSCC categories as given in their three submitsis. Commonwealth Edison should also clarify' conflicting statements concerning three of these welds as discussed in Section 2.3.5 of this report.
(3) Acceptance of Commonwealth Edison's position on inspection schedules for velds at Quad Cities 2 except for the IGSCC Category G welds, one of which is accessible for UT inspection but not scheduled for inspection. The ISI. program should be modified to include that weld in the inspection schedule.
(4) Acceptance of Commonwealth Edison's plan for visual inspection of one of the two inaccessible welds that are not scheduled for replacement.
(5) Rejection of Commonwealth Edison's position concerning.the second of the two inaccessible welds that are not scheduled for replacement.
A plan should be formulated and pursued.to ensure the integrity of this weld until it is determined whether it is or is not within the scope of Generic Letter 88-01 (i.e.,
whether or not the operating temperature is < 200*F).
).
(6) Rejection of Commonwealth Edison's position concerning changes-to the Technical Specification on ISI. The. Technical Specification should be amended to include the statement on ISI as required by Generic Letter 88-01, 40
7 w -
p 1
(7) Rejection of Commonwealth Edison's position concerning a
o The limitations of an-increase of unidentified leakage.
Technical Specification should be amended to include requirements for. plant shutdown 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 ir. crease.in rate of unidentified leakage in excess of 2 gpm its equivalent (rather than the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average as proposed by Commonwealth Edison).
(8) Acceptance of other portions of Commonwealth Edison's position-on leakage detection.
(9) Acceptance of the remaining portions of the CE Submittals.
- 5. REFERENCES l
" Technical report on Material Selection and Processing Guidelines l
1.
}
for BWR Coolant Pressure Boundary Piping," NUREG 0313, Revision l
2, U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor l~
Regulation, January, 1988.
O i
" Investigation and Evaluation of Stress-Corrosion Crc ' ing in Piping 2.
l.
of Light Water Reactor Plants," NUREG 0531, U. S. Nuclear Regulatory Commission, February, 1979.
L "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping,"
l 3.
i l-Generic Letter 88-01, U.S. Nuclear Regulatory Commission, January 25, 1988.
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l l
l 41 l
l l.
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