ML20064A463
| ML20064A463 | |
| 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 9009040255 | |
| Download: ML20064A463 (50) | |
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E'NCLOSURE-3 if
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TECHNICAL EhLUATION REPORT ON 1'[
RESPONSE FROM COMMONWEALlh EDISON W GENERIC LETTER 88-01
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PERTAINING W THE' QUAD CITIES STATION, UNIT 1 I
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VIKING SYSTEMS INTERNATIONAL Johnstown, Ohio Pittsburgh, Pennsylvania Washington, D.C.
9009040255 900021 If
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l TECHNICAL EVALUATION REPORT ON.
RESPONSE FROM COFN0NVEALTH EDISON TO GENERIC LEITER 88 PERTAINING 'lV THE' QUAD CITIES STATION, UNIT 1 Published February,.1990 prepared by Robert C. Bates.
Armand Lakner Viking Systems International.
2070 Wm. Pitt Way Pittsburgh, PA Prepared for:
U.S. Nuclear Regulatory Commission Washington, D. C. 20555 l
under m..
Contract No. NRC-03-87-028 Task Order 005
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7 ABSTRACT This report contains an evaluation of tr.e licensee (Commonwealth Edison).
submittal for Quad Cities Station, Unit I which was submitted.in i
-response to the NRC Generic Letter 88-01 in whirt Commonwealth Edison was requested to: (1) Furnish their current plans relating to piping replacement and other measures to mitigate IGSCC, inspection, repair, and leakage detection.
(2) Indicate whether they plan to fc.11ow the NRC Staff positions, or propose alternative measures. Commonwealth Edison's plans are_ evaluated in Section 2 of this report'in terms of q
compliance to NRC Staff positions. Section 3 contains evaluations of an alternative position concerning a change to the Technical Specificaticn on ISI, alternativet to portions to the NRC Staff position on-leakage detection, and an exception to the scope of Generic Letter
'8 8-01..
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.SUMHARY
-The Licensee, Comer tson, submitted a rerponse to the NRC Generic Letter 88 '.
,monwealth Edison's response pertaining to the austenitic stainless steel piping in the Quad Cities Statica, Unit l'(a BWR nuclear power plant) was evaluated-in terms cf: (1) Their previous,and planned actions to mitigate IGSOC to provide assurance cf continued long-term service.
(2).Their Inservice Inspection (ISI)
Program.' (3) Their Technical Specifications pertaining 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 of the welds previously known to be cracked) during inspection.
Commonwealth Edison enderses most of the 13.NRC Staff positions which are outlined in Generic Letter 88-01, but they applied provisions to 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 NRC 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 1, 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 schedules for IGSCC Category F welds are deficient, and RWCU piping that is outboard of the isolation' valves 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.
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CONTENTS i
ABSTRACT il
SUMMARY
iii CONTENTS 1
1.
INTRODUCTION.
2.
EVALUATION OF RESPO14SE TO GENERIC LETTER 88-01 2'
2.1 Documents Evaluated 2
2.2 Review of Commonwealth Edison's Responses to Staff 4
Positions and implementation of Those Positions 2.3 Review of Classification of Welds, Previous Mitigating 6
Actions, and Previous Inspections 2.3.1, Current IGSCC Classifications 6
2.3.2 Summary of Materials and Mitigating T:catments Prior 11 to the 1989 Refueling Outage (per CE Submittal No. 2) 2.3.3 IGSCC Resistant Welds (Conforming Materials) (per CE 13 Submittal No. 2) 2.3.4 Mitigating Actions During the 1989 Refueling Outage 14 2.3.5 Inspection Programs Prior to the 1989 Refucting Outage 15 (per CE Submittal No. 2) 2.3.6 Inspections During the 1989 Refueling Outage 18 2.3.7 Evaluation and Recommentations 19 2.4 Current Plans for Mitigatin; Actions 20 2.4.1 Commonwealth Edison's Position 20 2.4.2 Evaluation of Conformance to Staff Positions 21 and Recommendations 20 2.5 Plans for Future Inspections 2.5.1 Commonwealth Edison's Position 21 iii
wy s:g 2.5.2 - Inaccessible Welds 22 2.5.3 Methods and Personnel 23 23 2.5.4 - Sampic Expansion 2.5.5 Evaluation and Recommendation 23 24 2.6 Changes in_the bchnical Specification Concerning ISI 2.7 Confirmation of Ixak Detection in the Technical Specification 25 28
- Plans for Notification of the NRC of Flaws 25 2.8.1 Commonwealth Edison's Position 25 2.8.2 Evaluation and Recommendation 25 27 3.
ALTERNATIVE POSITIONS AND EXCEPTIONS 3.1-Alternative Position Concerning ISI in the Technical Specification 27 3.1.1 Commonwealth Edison's Position 27 3.1.2 Evaluation and Recommendation 28 29 3.2 Leakage Detection in the Technical Specification 3.2.1 Conformance with Regulatory Guide 1.45 -
30 32 3.2.2 Leakage Limits 32 3.2.3 Frequency of Leakage Monitoring 3.2.4 Definition of Unidentified Izakage 33 34 3.2.5 Operabilby of Monitoring Instruments.
3.2.6 Evaluation and Recommendations 34 35 3.3 Welds Excluded from IGSCC Program 35 3.3.1 Scope of Generic Letter 88-01 3.3.2 Commonwealth Edison's Position 35 3.3.3 Evaluation and Recommendation 36 iv
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CONCLUSIONS AND RECOMMENDATIONS 37 a
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REFERENCES 42 a
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- 1. INTRODUCTION Intergranular stress corrosion cracking (IGSCC) near veldments in-Boiling k'ater Reactor (Bk'R) piping has been occurring for almost 20 years. Substantial efforts in research and development have been sponsored by the Bk'R Owners Group for IGSCC Research, and the results of this program, along with other related work by vendors, consulting 1
firms and confirmatory research sponsored by the'NRC, have permitted the development of NRC Staff positions regarding the IGSCC problems.
1 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 Bk'R's and holders of construction permits to:
(1) Furnish their current plano relating to piping replacement, ii.spection, repair, and leakage detection.
(2) Indicate whether they:
-(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.
(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 1
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in the section on ISI that the inservice inspection program for piping will be in conformance_with the staff positions _
j on schedule, methods and personnel, and sample expansion.
l (4) Confirmation of plans to ensure that the Technical Specification related to leakage detection'will be-in conformance with the 1:
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 IWB-3500 criteria'.
of Section XI of the ASME Code for continued operation without evaluation, or a change found in the condition of the welds l
l previously known to be cracked, and an evaluation of the flaws I
l for continued operation and/or repair plans.
.This report contains a technical evaluation of the response which Comm nwealth Edison'(sometimes called CE in this report) submitted in response to the NRC Generic Letter 88-01 pertaining to'the Quad Cities Station, Unit 1 (hereafter called Quad Cities 1).
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- 2. EVALUATION OF RESPONSE.TO GENERIC LETfER 88-01 L
This evaluation consisted of a review of the response to NRC Generic.
I Letter.88-01 of January 25, 1988 by Commonwealth Edison pertaining to Quad Cities 1 to determine if their performance and plans are in l
l conformance with the NRC Staff positions or if proposed alternatives l
L 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 2
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1 provided by the Licensee in the following documents.
(1) "Dresden Station Units 2 and 3 Quad Cities Station Units I and 2, LaSalle County Station Units"1 and 2, (Response to) Generic Letter 88-01, 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 L d 69155, Docket Nos. 50-254/265," Commonwealth Edison, One First National Plaza, Chicago, Illinois 60609, July 21, 1989.
(3) " Quad Cities Station Unit 1. Inspection Plan for Piping Susceptibic to Inteigranular Stress Corrosion Cracking (IGSCC) Docket No. 50-254 " Commonwealth. Edison,'72' West Adams Street, Chicago, Illinois 60609 June 9, 1989.
(4) " Quad Cities Nuclear Power Station Unit 1, Intergranular Stress Corrosion Cracking (IGSCC) Final Inspection Results, Docket No. 50-254," Commonwealth Edison One First National Plaza, Chicago, Illinois 60609, December 18, 1989.
These documents are listed in the order-in-which they were received-for this review (not the chronological order in which they were dated), and hereafter, in'this report, they will be referred to as CE Submittals No. 1, No 2, No. 3, and No 4. Collectively these documents will be referred to as-the CE Submittals.
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2.2-Review of Commonwealth Edison's Responses to Staff Positions and Implementation of Those Positions.
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Generic Letter 88-01 outlin.s thirteen NRC Staff positions perta'ining to'(1) materials, (2)' processes, (3) water chemistry, (4) weld o 4rlay, (5) partial replacement, -(6) stress improvement of' cracked weldments. (7) clamping devices, (8) crack evaluation t
and repair' criteria,'(9) inspection methods and personnel, (10) t' inspection schedules, (11) sample expansion, (12) leak detection, and (13) reporting requirements. Generic Letter.88-01 states that the licensee should indicate'in their submittal whether they endorse these NRC Staff positions or propose alternative positions. Table 1
1 of this report, which is based on a similar table in CE Submittal No. 2 and discusrion throughout-the CE Submittals, shows Commonwealth Edison's positions concerning the 13 NRC Staff positions.
Note that Commonwealth Edison endorses most of the 13 NRC Staff positions. They proposed alternative positions to portions of, the item on leakage detection (discussed'in'Section 3.2).
They 1
also. stated that.they applied a provision on inspection schedu..es, but it actually applies to IGSCC classifications of welds between O
castings and is discussed in Section 2.3.3.
Finally, they applied'
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a provision to the item on Crack Evaluation and Repair Criteria (i.e., they plan.to 1.. corporate the favorable stress distribution for' calculations for stress improved welds). This provir. ion is acceptable and will not be discussed elsewhere in this report.
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-Table 1 Summary of CE's Responses to Staff Positions CE Has/Will CE Accepts NRC Applied = Consider for Staff Position Staff Position In Past Future Use y,,( b) yes(a) y,,
- 1. Materials
- 2. Processes yes yes yes:
- 3. Water Chemistry.
yes no yes yes( )
- 4. Weld Overlay yes yes yes(b) 1
- 5. Partial Replacement yes
-yes
- 6. Stress Improvement of yes(b)
Cracked Weldrents yes no
.yes(b)
- 7. Clamping Devices yes yes
- 8. Crack Evaluation and yes(b) yes(c) no Repair Criteria
- 9. Inspection Method and Personnel yes yes yes
- 10. Inspection Schedule yes(a) no yes
- 11. Sample Expansion yes-no yes
.yes(d) nd yes
- 12. Leak Detection i
yes(b)
- 13. Reporting Requirements
_yes no (a) Commonwealth Edison stated that they applied provisions to inspection schedules, but they were actually applied to materials (i.e., assignment of IGSCC classifications to welds between castings). See text for discussion.
(b) Cormonwealth Edison will implement this item as necessary.
(c) Provisions applied. See text for discussion.
(d) Alternate proposal presented on portions of NRC Staff position.
See text for discussion.
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2.3 Review of Classification (of Velds. Previous Mitigatina 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 1 ICSCC pro 3raa'.
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 l
of the number of welds at Quad Cities 1 in each of the various IGSCC. categories on a system-by-system basis. 'Ihe IGSCC.
classifications'of individual welds are not listed in CE
' Submittal No. 1, but such a list is contained in CE Submittal j
No.2[andthatlistwasusedtoconstructthesummary presented in Table 2b of this report. The format of this table is patterned after that.in Table 2a.
Note that several
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1 (1) The total number of welds listed in CE Submittal j
No. 2 is one taore than that listed in CE Submittal j
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No. 1 (254 versus 253).
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1 (2) The number of IGSCC Category A velds listed in CE i
Submittal No. 2 is two less than that listed in CE Submittal No. 1 (55 versus 57).
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(3) The number of ICSCC Category C welds listed in CE I
Submitta). No. 2 is onn less than that listed in CE Submittal'No. 1.(105 versus 106).
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1 Table 2a Summary of IGSCC Classification of Welds (Based on CE Submittal No. 1)
Diameter No. of Welds of Indicated IGSCC Category System Inch A
B C
D E-F G
Total Recirulation Outl et s.'.
28 2
0 28 0
-2 0
0 32 Noz-SE 28 2
0 0
0 0
0 0
-2 Header 22 8
0 7
2 3
0 0
20 Risers 12-0 0
22 0
19 0
0 41 Noz-SE 12 10 0
0 0
0 0
0--
10 Bypass 4
4 0
0 2
0
'O 6
12 SDC 20 0
0 4
9 0
-0 4"
17 LPCI 16 0
0 25 0
1 0
0 26 Core Spray 10 1
0 20
.0 6
0
.0 27 Jet Pump Inst 12, 8, 4 0
0 --
0 3
0 0
7 10 Sp Noz, b
RWCU, Hd-Sp 6
27 0
0 8
0 0
2 37 C
Hc
'p, Hd Vt, 4
3 0
0 13 0
0 3
19 CRL Totals 57 0
106 37 31 0
22 253 Notes:
- a. Includes one inaccessible weld,
- c. Includes one inaccessible weld on Rd. Sp.
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Table 2b
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Summary of IGSOC Classification of Welds (Based on CE Submittal No. 2).
Diameter No.~of Welds of Indicated IGSCC Category System Inch A
B C
D E
F G
Total Rectrulation Outlets 28 2
0 28 0
0 2
0 32 Noz-SE 28 2
0 0
0 0
0 0
2 Header 22
.8 0
7 2
2 1
0 20 L
Risers 12 0
0 22 0-13 6
0 41 ~
Noz-SE 12 10
-- O O
O' O
O O
10 l
Bypass 4
4 0
0 5
0 0-3 12 SDC 20 0-0 3
10 0-0 4a 17 LPCI.
16 0
0 25 0
0 1
0 26 1
Core Spray 10 1
0 20 0
0 6
0 27 Jet Pump Inst 12, 8, 4 0
0 0
3 0-0 7
10 D
RWCU, Hd Sp 6
27.
0 0
8 0'
C 2
37-Sp Noz,-
L c
. Hd Sp, Hd Vt, 4
1 0
10 15 0
0 4
20
- CRD
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, Totals 55 0
105 43 15 16 20 254 l
Notes:
- a. Includes one inaccessible weld.
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- c. Includes one inaccessible weld on Hd. Sp.
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4 (4)' The number of IGSCC. Category D welds listed dn CE rl Submittal No. 2 is six more than that listed in CE Submittal No. 1 (43,versus 37).
(5) The number of IGSCC Category G welds listed.in CE Submittal No.~2 is two less than that listed in CE Submittal No.1 (20 versus 22),
i (6) Sixteen of the 31 Welds classified as IGSCC Category
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E welds listed in'CE Submittal No. I are classified as IGSCC Category F in CE Submittal No. 2.
These changes in classifications of these welds are due o
r to flaws that were found in the overlays on these i
welds, several of which were repaired.
CE Submittal No. 3 also contains a table that summarizes the veld population at Quad Cities 1, pertinent portions of which.are reproduced in this report as Table 2c. Note that the number of welds in each IGSCC classification, according to Table 2c, is the same as that shown in Table 2b except for the 4-inch diameter welds in the Head Vent.
Head Spray, and Control Rod Drive, tUi detailed listing of which, according to CE Submittal No. 2) is shown in Appendix A.
Two of the welds listed as IGSCC Category D in Table 2b in these systems are listed as IGSCC Category A in Table' 2c.
I Commonwealth Edison did not explain the reasons for the differences:noted above in Tables 2a, 2b, and 2c, but f
hereafter, for purposes of discussion of mitigating treatments and inspections performed prior to 1989, it is assumed that Table 2b is correct (rather than Table 2a or 2c) because Table 2b is based on the description of welds contained in CE Submittal No. 2; whereas the information shown in Tables L
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i Table 2c Summary of IGSCC Classification of Welds (BasedonCESubmittalNo.'J)
Diameter No. of Welds of Indicated IGSCC Category System ~
Inch A
B C
D E
F G
Total Recirulation Outlets 28 2
0 28 0
0 2
0 32 Noz-SE 28 2
0 0
0 0
0 0
2 Hesder 22 8
0 7
2 2
1 0
20 Risers 12 0
0 22 0
13 6
0 41 Noz-SE 12 10 0
0 0
0 0
0 10 Bypass 4
4 0
0 5
0 0
0 3
10 0
0 4a 17 LPCI 16 0
0 25 0
0 1
0 26 Core Spray 10 1
0 20 0
0 6
0 27 Jet Pump Inst 12, 8, 4 0
0 0
3 0
0 7
10 D
RWCU, Hd Sp 6
27 0
0 8
0 0
2 37 Sp Noz, c
Hd Sp,'Hd Vt,-
4 3
0 0
13 0
0 4
20 CRD Totals 57 0
105 41 15 16 20 254 Notes:
- a. Includes one inaccessible weld,
- c. Includes one inaccessible weld on Hd. Sp.
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i 2a and 2c was provided only in summaries.
However, note that Table 2c also contains a summary _of the weld population (including IGSCC classification) following i
the December, 1989 Refueling Outage. Inasmuch as this is the only listing of the weld population for that point in time, discussions in this report of mitigating treatments m
performed =during the December, 1898 Refueling. Outage, inspections performed during the December,'1989 Refueling
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Outage, and plans for future inspections.are based on the welds population given in Table 2c.
2.3.2 Summary of Materials and Mitigating Treatments Prior to the 1989 Refueline Outape-(per CE Submittal No. 2)
CE Submittal No. 2 lists the justification for the IGSCC classification frr 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.
Note that 33 welds are classified as IGSCC Category A because they contain materials considered by Commonwealth Edison to be resistant to IGSCC, Note also that two of the IGSCC Category A welds were produced using heat sink welding (HSW).
The remaining 20 IGSCC A welds were 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 (MSIF), were applied to 106 welds, 105.
of which are classified as IGSCC Category C.
One of the.
stress improved welds was subsequently overlayed and is classified as IGSCC Category F.
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l Weld overlays were applied to a total of 31 welds: 21 of these are classified as IGSCC Category E, and 8 of these are classified as IGSCC Category F.
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Table 3 Summary of Mitigating Treatments and Materials No. of No. of Velds
Indicated Treatment h
Caten Caten Material Sirr CRC HSW IHSI HSIP 0.L.-
A 55 33 8
12 2
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-C 105 53 52' L
D 43 l-E 23 23 L,
F 8
1 8
G
'20 1'
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- For a discussion of the materials considered to be conforming materials, see Section '.3.3.
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7 2.3.3'IGSCC'Resistai.t Welds (Conformine Materials) 4.
(per CE Submittal No. 2)'
Welds are considered-by Commonwealth Edison to be resistant to IGSCC and are classified as IGSOC Category A if they
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contain any of theLfollowing combinations of materials for.
base metal and weld metal:
1 Base Metal Weld Metal Base Metal 304L S.S.
Conforming 304L S.S.
304L S.S.
Conforming S.S. Casting
-C.S. Pipe Conforming S.S. Caeting q
C.S. Pipe Non-Conforming S.S. Casting S.S. Casting Non-Conforming S.S. Casting.
j where:
(1) C.S. pipe is carbon steel.
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(2) Castings are stainless steel which contain > 0.035% carbon.
(3) Conforming veld metal is either: Type 308L stainless steel or Type 309L stainless steel.
(4) Non-conforming weld metal is stainless steel which contains > 0.035% carbon.
Note that castings and some veld metal (that used for welds
'l which join two casting or some of.the welds between carbon-steel pipe and castings) contain carbon contents > 0.035%.
Commonwealth Edison's justification for classifying these j
welds a.s 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 in Category A.
The Staff Position on inspection schedules 13 A
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states'that ' welds joining such castings (in the form.
.of pump _and valve bodies) to piping have been relatively free of IGSCC. This may be attributable to a favorable
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stress distribution.' _1his good service experience includes both cast and weld material with carbon content higher than 0.035%. Therefore, it is logical to extend
-the Staff Position, which places high carbon cast material r
joined.to resistant material in Category A, to'also include cast material joined to cast material in Category A."
2.3.4 Mitigating Actions During the 1989 Refueling Outage During the December, 1989 Refueling Outage,_ extensive mitigating actions were performed as summarized below:
.(1) Weld overlay repairs were applied to two welds (Weld Nos. 02G-S4 and 02M-S3.
(2) Mechanical Stress Improvement (MSIP) treatments (followed with UT inspection, with no flaws detected) vere applied to a total of 29 welds. MSIP treatments' vere planned for 36 welds, but'7 of the welds could 3
not be treated because of weld geometry or interferences.
(3) Piping modification replaced' five welds (one IGSCC Category A, three IGSCC Category D, and one inaccessible IGSCC Category G) with six IGSCC Category A welds in the RWCU.-
(4) Piping modification removed 14 welds (one IGSCC Category A, 12 IGSCC Category D, and one IGSCC Category G) in the Head Spray, and a blind flange 14
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3 was installed on the Head Spray Nozzle.
(5)= Piping modification removed four welds (one ICSCC Category A, 2 IGSCC Category D, and one IGSCC Category
'l G) in the CRD return line, and an end cap was welded to the Safe End of the CRD Return line.
1 The veld population and the number of welds in each of the various IGSCC Categories, according to CE Submittal No. 3, is shown on the bottom line of Table 2c.
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2.3.5 Inspection Programs Prior to the 1989 Refueling Outage (per CE Submittel No. 2)
CE Submittal No. 2 contains a list of welds that were inspected during Refueling Outages 8 and 9 (01/86 through 03/86 and 09/87 through 11/87, respectively). Those l
inspections.are summarized in Table 4 and-in the following paragraphs.
It is presumed (but not actually stated in the CE Submittals) that those inspections were performed per NUREG 0313, Revision 2 (using methods and' personnel qualified under the NRC/EPRI/BWROG coordination plan as upgraded in September, 1985) because: (1) as indicated in Table 1, the NRC Staff position concerning-inspection methods and personnel has been previously applied,-(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 l
of welds in CE Submittal No. 2).
IGSCC Category A Welds: Eighteen of these welds (33%)-
L were inspected during Refueling Outage No. 8. Refueling l
Outage No. 9, or both refueling outages (six of these welds were inspected during both outages). No flaws 1.'
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Table 4 i
Summary of Inspection Schedules for Quad Cities 1 No. of(a)
No. Inspected /Sched.
-Welds per During R.O.#
During Required by Cater. CE*2 CE#3/4 08 09 10 R.O.#11 Generic Letter 88-01 A
55 57(D) 9 15 6
0 25% every 10 years (at least 12% in 6' years) 50% every 10 years (at B
0 0
least 25% in 6 years)
C 105 105 18 100 105 0
All within the next two i
refueling cycles, then-all every 10 years (at 50%
in 6 years)
D 43 25 21 23 25 0
All.every 2 refueling cycles
- t E
15 15 3
15 15 0
50% next refueling cycle, then a avery 2 refueling cv ~ ~
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F 16 16 5
15 16 0
All every refueling outage l
CC)
G 20 17 0
0 15 0
All next refueling cycle j.
p.
O s
l Notes:
b (a) CE62, CE#3, and CE#4 indicate CE Submittels No. 2,.No. 3, and No. 4, respectively.
Numbers'under CE#3/4 indicate the number-of welds after mitigating act. ions during R.O. No. 10.
1 (b) Includes two inaccessible Category A welds added in RWCU during Refueling Outage No. 10. -These welds were UT inspected prior installation inside the flued head penetration.
(c) Includes two IGSCC Category G inaccessible welds (one in the RWCU and the other on the SDC).
l Dates of refueling outages are i
R.O.#
Date R.O.# Beginning Date 08
'01/86-03/86 10 09/89 09 09/87-11/87 11 Not disclosed l
I 16 l
l l
l
Y,
~
l a
i t
'l
- were found.
j IGSCC Catenory C Welds: All of these welds were inspected at:1 east once during Refueling Outage Nos. 8 and 9.
Thirteen of these welds were inspected during both of It is not clear whether some of those those outages.
inspections were the post-treatment inspections required I
.following stress improvement treatments, but in any event.
Commonwealth Edison stated that all of the IGSCC Category C velds received post-SI inspections. No flaws were reported for any of these welds.
IGSCC Category D Welds: All except one of these welds (Weld No. 03-F7 in the Control Rod Drive system) were.
inspected at least once during Refueling Outage Nos.
8 and'9. Two of the welds were inspected during each Commonwealth Edison stated that all of the outages.
IGSCC Category D welds have'been inspected, so Weld _No.
03-F7 must have been inspected during an earlier rdfueling outage.
IGSCC Category E Welds: Visual indications were found in 14 of these welds in 1984. Inspections of two of j
these welds were conducted during Refueling Outage No.
8, and all 14 were inspected during Refueling Outage
=No. 9.
An indication was found on one weld (Weld 02J-S4 in the Recirculation system), and the remainin8 ligament is, according to CE Submittal No. 2, 0.33 inch. The weld overlay on the fifteenth Category E weld was applied during Refueling Outage No. 9 after indications were found in that veld. Post treatment inspection of that weld revealed no indications.
IGSCC Category F Welds: All of the welds that are
[
l-17 l
o k
~.
.i.-
currently classified as IGSCC Category F were inspected =
during either Refueling Outage No. 8 or Refueling Outage No. 9 or both. Several of these were previously weld overlaid, and no indications were found in the overlays daring the~ inspections during Refueling Outage 9.
Others had not been previously overlaid, and cracks were found for the first time during Refueling Outage No. 9.
Weld overlay repairs were applied and inspected with satisfactory results at that time..
2.3.6 Inspections Duri g the 1989 Refuelinn OuteRe A total of 182 welds were inspected during the December, 1989 Refueling Outage.
A summary of the number of welds of each IGSCC Category that were inspected is shown in Table 4.
This table also contains the number of welds of each IGSCC category that should be inspected per Generic Letter 88-01. Note that if the numbers of welds in each IGSCC Category are correctly stated in CE Submittals No. 3 e6d 4, the inspections performed in 1989 completely comply with i
the requirements provided in Generic Letter 88-01.
Concerning the ;3rformance and results of the 1989 examinations, CE Submittal No. 3 states:
L j:
" Lambert, MacGill, and Thomas, Inc performed the ultrasonic examinations using level II and III examiners 1'
l qualified by EPRI after September 10, 1985. Both manual l
and automated UT techniques were utilized."
"No new IGSCC-like flaw indications were identified this However, indications were detected in the overlay l
outage.
material of three weld overlay repairs: 02G-S4, 02D-S3, i
and 02C-#S3. For weld overlay 02G-S4, flaw indications 18 9
0 r-----
a
,e ti
- 2 were removed and the weld overlay was repaired. The>
flaw indications in the weld overlay repairs on welds
]
02D-S3 and 020-S3 were' judged to be welding defects and found acceptable for continued operation without g
additional repairs."
y 2.3.7 Evaluation and Recommendations j
l According to CE Submittal No. 3, a total of 235 welds are currently within the scope of Generic Letter 88-01. As a result of extensive programs to mitigate IGSCC including piping. replacement, solution heat treating, internal cladding, heat sink welding, either 57 of these welds are IGSCC Category A welds. An additilonal 106 welds,105 of which are classified
]
as IGSCC C, were stress improved. Weld overlays have been t
applied to a total of 41 welds to repair flaws. These mitigating treatments and the assignment of IGSCC classifications (with one exception) have followed NRC; Staff guidelines. The one exception is an overlayed weld (Weld 02J-S4) containing a flaw in the overlay. This weld should be reclassified as IGSCC Category F rather than IGSCC Category E.
It was not revealed by Commonwe.=ith Edison whether this weld was inspected during tLe 1989 Refueling Outage as required by Generic Letter 8U-01.
l o
Discrepancies exist in the listing of the weld populations in the CE Submittal. Of particular significance are the differences in CE Submittals No. 2 and No. 3 because these j
submittals (which both report the weld population and IGSCC classifications shortly before December, 1989 Refueling Outage) differ in the reported numbers of IGSCC Category A welds and IGSCC Category D welds. These differences should be reconciled.
In addition, if the two welds reported to be IGSCC Category A in CE Submittal No. 3 are actually IGSCC 19
+
Category D welds (as reported'in CE Submittal No. 2), plans for future inspections of these two welds should be adjusted accordingly, i.e., they'should-be inspected per recommendations for IGSCC Category D welds provided in Generic
-Letter 88-01.
2.4 Current Plans for Mitigating Actions 2.4.1 Commonwealth Edison's Position The CE Submittals do not list any specific plans for future mitigating actions except that Hydrogen Water Chemistry will be used (scheduled time for operation: late 1988)and weld overlays will be used to reinforce welds that are found to have flaw indications.
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 Cities 1.
Although 42 welds (or_possible 44 welds, depending on which submittal is correct) remain unmitigated (25 IGSCC Category D welds and 15 IGSCC Category G welds) and Commonwealth Edison did not disclose any additional ~ plans for mitigating IGSCC, acceptance of their position is recommended provided they follow the reccmmended inspecti,n scheudules as delineated in Generic Letter 88-01.
20
[
J
7
'b c
2.5 Plans'for Future Inspections
- )
2.5.1 Commonwealth Edison'c Position j
~
CE Submittal No. I states that inspection schedules for Quad s
Cities 1 are being revised to reflect the requirements for~
)
inspection schedules as delineated in Generic Letter 88-01
]
with the exception of the inaccessible IGSCC Category G welds that are discussed later. The following qualifying statement is contained in CE Submittal No. 2.
l "It should be noted that future inspection schedules.
... may be subject to change. However, at all times.
Quad Cities Unit I will continue to meat the inspection schedules of the IGSCC categories as presented in Generic Letter 88-01."
The inspections conducted during the December, 1989 Refueling Outage reflect the result of the revised schedules inasmuch as they satisfied the ins'pection requirements of Generic 1
Letter 88-01 with the possible exception of the two welds for which-the'IGSCC classications are in doubt (i.e., the two welds that are classified as IGSCC Category A in CE Submittals No. 3 and No. 4 and classified as IGSCC Category D in CE Submittal No. 2). On the other hand,'according to CE Submittal No. 2, no inspections are planned for Refueling Outage No. 11 (the next refueling outage, scheduled for the Fall of 1990). This is shown in Table 4.
Commonwealth Edison justifies these plans (or lack of plans) for welds classified as IGSCC Category A, IGSCC Category C, IGSCC Category D, and IGSCC Category E with the following V
statement contained in CE Submittal No. 4:
21
(
,=
y e
"Because the sc' ope of the examinations performed satisfies the Generic' Letter 88-01 inspection requirements of categories A, C, D, e-4 E welds'for two (2) refueling cycles and because
. sew flaws are found this outage, no ultrasonic examination of the aforementioned welds will be performed during the next Unit' I refueling outage
-(currently scheduled in the Fall of 1990)."
Although no IGSCC Category G welds remain at Quad Cities 1 (the 17 welds classified as IGSCC Category G welds following the piping removal and other mitigating actions performed l,
L during the December, 1989 Refueling Outage will, no doubt, l
be reclassified to IGSCC Category D sinco they were inspected l
during that outage), several IGSCC Category G welds remain at Quad Cities 1.
No justification is contained in=the CE Submittals for not performing inspections of IGSCC Category.
F wel'ds during the-next refueling outage as required by Generic Letter 88-01.
2.5.2 Inaccessible Welds Quad Cities 1 contains two inaccessible IGSCC Category A welds which were previously described and two IGSCC Category G welds which are described below along with plans i
concerning these welds.
l-i:
A branch pipe connection on the RWCU suction line which l
L is completely encased in a reinforcement saddle. The saddle strerathens the weld and reduces stress, but it precludes UT inspection. Visual inspection through a I
weep hole is planned, t-A weld located inside the conta1nment penetration assembly 11 on the Residual Heat Removal / Shutdown Cooling line.
22
F u.:,
.n +.
.~
l.{. 'f
}\\ l,
- il
.A, 4'
According to CE Submittal No. 1, acoustic emission 3,
4 monitoring of this location is being considered.
According to CE Submittal No. 2, a heat transfer analysis l
1s planned to determine if its operating temperature may be < 200*F. However, until it is confirmed that this weld is or 1s-not within the scope of Generic Letter f
88-01, it should be treated as an ICSCC Category G weld.
Accordingly, plans to assure its integrity should be
- pursued, 4
r
. 2.5.3 Methods and Personnel in i.
i
[
The augmented inspection program will be conducted using methods and personnel in conformance with the NRC Staff f
positions as delineated in Generic Letter 88-01 and NUREG 0313, revision 2.
l-2.5.4 Sample Expansion j
1 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.
q q
s 2.5.5 Evaluation and Recommendations l
.i No addition UT inspections are needed during the next refueling outage for velds of IGSCC Categories A, C, D, and u
E to satisfy the requirements of Generic Letter 88-01 for
]
welds of these categories, and all welds classified as IGSCC j
l Category G will, no doubt, be reclassified as IGSCC Category D since they were inspected (with no flaws reported) during l
the 1989 Refueling Outage. Although no longer range plans were presented by Commonwealth Edison, they affirmed that they would comply with the requirements of Generic Letter 23
Q t.
88-01, so acceptance ~of Commonwealth Edison's position pertain R
l'
^ to those welds 1s recommended. On the other hand, Generic Letter 88-01 requires inspection _of IGSCC Category F welde during every refueling outage. Since none of these welds is scheduled for inspection during the next refueling outage,
' Commonwealth Edison's plans pertaining to IGSCC Category J
3 F welds are deficient. Thus, rejection of.this portion of Commonwealth Edison's position is recommended. It is further recommended that these plans should be revised to include f
inspections of these welds in compliance with the NRC Staff position as delineated in Generic Letter 88-01.
t Plans for one of the inaccessible welds (i.e., visual inspections) is acceptable.
A plan to investigate acoustic 1
emission for the other inaccessible weld was presented in L
CE Submittal No. 1, but apparently that plan was abandoned becau'se the only plan concerning this weld presented in CE
.j Submittal No. 2 is to perform a heat transfer analysis,to determine if the operating temperature is ( 200'F. Plans to ensure the integrity of this weld should be formulated and pursued until it is confirmed that it is or is not within the scope of Generic Letter 88-01 (i.e., whether or not 1ts 1
operating temperature is greater than or less than 200'F).
J
.i Commonwealth Edisons positions concerning methods and i
personnel and concerning sample expansion follow NRC Staff guidelines, so acceptance of these positions is recommended.
fl
-1 l
2.6 Changes in the Technical Specification Concerninn ISI
.1 Commonwealth-Edison proposed an alternative position to the NRC I
Staff position concerning a change to the Technical Specification.-
This alternative position is discussed in Section 3 of this report.
l t
1 24 l
u l
l J
~l i:
u 2.7 Confirmation of Leak Detection in '.he Technical Specification Table 5 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 leakaCe detection as delineated in Generic Letter 88-01. Note that Commonwealth Edison stated that portions of the Quad Cities 1 Technical Specification pertaining to leakage are in conformance with tN NRC Staff position j
(or vill be revised to be in conformance eith da NRC Staff position), but they proposed alternative posititer,concerning other
]
portions. Thus, discussion of leakage detection is deferred to Section 3 of this report, " Alternative Positions and Exceptions."
i 2.8 Plans for Notification of the NRC of Flaws 2.8.1 Commonwealth Edison's Position j
CESubmittalNo.1statesthattheNRCwillbenotifiedof flaws in accordance with the NRC Staff position as delineated in Generic Letter 88-01. Additionally, notification will be provided of the evaluation by the Commonwealth Edison Engineering Department for the conditions for continued operation and/or the necessary corrective action to be taken.
Notification vill be made by the Consolidated Edison 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.
25 i
i
.{
Table 5 i
i Licensee Positions on Leakage Detection Already TS will be' Alternate (*)
Contained Changed Position Position in TS to Include Proposed 4
yes
- 1. Conforms with Positicn C of Regulatory Guide 1,45
- 2. Plant shutdown should be initiated when:
/s) within any period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> yes or less, on increase is indicated in the rate of unidentified leakage in j
excess of 2 gpm, or (b) the total unidentified leakage yes attains a rate of 5 gpm.
a yes
- 3. Leakage monitored at four hour intervals or less.
- 4. Unidentified leakage includes all 1
except:
(a) leakage into closed systems.
yes or l
i (b) leakage into the containment yes atmosphere from sources that are located, do not interfere with monitoring systems, or not from throughwall crack.
- 5. Provisions for shutdown within 24 yes hours due to inoperable measurement instruments in plants with Category D, E, F, or G welds.
-(a) See text for discussions concerning alternate proposals.
26
i t
t l
- 3. ALTERNATIVE POSITIONS-AND EXCEPTIONS si a
3.1 Alternative Position Concernine ISI in the Technical Specification 3.1.1 Commonwealth Edison's Position f
-- I It is the position of Commonwealth Edison.that it is not appropriate to change the Technical Specifications to include j
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 Programs to include statements indicating conformance to Generic Letter.88-01. Their reasons are quoted below from CE Submittal No. 1.
'I 1
"The amendment would unnecessarily clutter the technical specifications with information not appropriate for l
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 l
specifications and ultimately in the plant technical specifications, as given in the Interim Policy Statement I
on Technical Specification Improvements, 52FR3788, February 6, 1987."
{
"As the industry and the NRC gain more insight into the l
l-causes of, and methods for prevention of IGSCC, the requirements in this area vill be changing. Therefore, addition of a reference to the generic letter in the l
27 l
f e
'e technical specifications would require that the technical specifications be updated as.the requirements in this j
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 f
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 jl section on ISI will conform with the NRC Staff position on schedule, methods and personnel, and sample expansion. Thus rejection of the Commonwealth Edison position is recommended.
9 It is'further recommended that Commonwealth Edison should amcnd'the Technical Specification on ISI for Quad Cities 6
1 to include a statement that the ISI program will conform with the NRC Staff position as delineated in Generic Letter 88-01.
3.2 Leakage Detection in the Technical Specification l
CE' Submittal No. I states that certain exceptions concerning the NRC Staff position on leakage detection are needed to avoid unnecessary plant modifications or unnecessary restrictive operating conditions at Quad Cities 1.
These exceptions, as stated in CE Submittal No. 1, are as follows:
(1) " Individual identified leakage is not flow-metered, but all identified leakage is collected and conducted to a separate collection system from unidentified leakage. Total 1
28 i
a il-e identified leakage is monitored via the drywell equipment drain sump pump discharge flow totalizer meter."
a.
(2) " Sump operability-is defined by the station as the ability j
to measure reactor coolant leakage rather than strictly de g nding on the operability of a leakage measurement f
Since only one channel exists for unidentified instrament.
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."
l In response to a Request for Additional Information (RAI) concerning-1 alternate methods of mee.:.uring reactor coolant leakage rather than.
j strictly depending on leakage measurement instrument, Commonwealth Edison replied in CE Submittal No. 2 as follows:
i "The ability to measure reactor coolant leakage can be l
accomplished by using sump pump flow recorder, timing the duration of pump operation or monitoring the input into Rad 1,
ll I'
k'as te. "
"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 accuracy of this determination will be less than 90%; however, the integration can be conservatively performed to determine a bounding value for leakage."
"In a similar way, the duration of sump pump operation can be timed.
A flow rate can be multiplied by the elapsed time 29
l 7
,s g1 o
to determine flow. The flow rate can be chosen to bound previous flow rates recorded on the control room recorder "
"The sump pumps input into the Waste Collector Tank in the L i, t
Rad Waste system. By reading the tank level increase at.the time of sump pump operation, the leakage can be determined.
d Because the relative error of this method is greater than 20%,
this method could be used to substantiate the two methods
'l previously described."
Commonwealth Edison's response to the RAI (CE Submittal No. 2) also included hformation used to construct Table 5 of this report which shows t*iat some of the requirements concerning leakage detection as de11 nested in Generic Letter 88-01 are currently contained in the Quad Cities 1 Technical Specifications, others 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.
3.2.1 Conformance with Regulatory Guide 1.45 Generic Letter 88-01 states:
" Leakage detection systers should be in conformance with
(
Position C of Regulatory Guide 1.45 ' Reactor Coolant L
L 1
Pressure Boundary Leakage detection Systems,' or as l
otherwise previously approved by the NRC."
CE Submittal No. 2 contains the following statements:
l
" Reg. Guide 1.45 Position C.5 states: 'The sensitivity and response time of each leakage detection system in regulatory position 3 above employed for unidentified 30 i
d
>t-Isakage should be cdequ:te to dstxct a leckage rate, l
oritsequivalent,ofonegpminlessthanonehdr.'-
t The discussion!regarding this position further clarifies ~
this point._ It states in part: 'all detector systents -
1
'should respond to a one gpm, or its equivalent, it w te 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 Drywell Floor Drain Sump from-L 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 monitoring and monitoring of airborne gaseous L
radioactivity, are also accomplished by manual actions "
j i
1 1
"The leakage detection systems are not able to detset I
L a one gpm leakage increase in one hour or less. However, indirect indications such as primary containment 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 L
L following seismic events that do not require plant shutdown. The airborne particulate radioactivity j
monitoring system should remain-functional when subjected j
to the SSE.'"
"The piping system from the drywell sumps to RAD Waste
,j is not seismically designed. The airborne particulate radioactivity monitor and the gaseous radioactivity 31 o
l 1
d' c.
~
I; a
e w
u s
monitor are seismically designed. The monitors are part
-of the High. Radiation Sample System implemented to meet NUREG 737 item II.B.3."
f 3.2.2 Leakane Limits q
Generic -Letter 88--01 states:
" Plant shutdown should be initiated for inspection and
- I 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 />
- e 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."
h A
Note from Table 5 that the Quad Cities 1 Technical Specification contains requirem ots that conform with tihe NRC Staff position concerning the 5 gpm total unidentified leakage. Ilowever, both of the CE Submittals contain the following statement g
t "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
't t
will preclude unit shutdown due to variations in measured
,i L
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 Frequency of Leakare Monitoring l
Generic Letter 88-01 states:
"For sump level monitoring systems with fixed-measurement-interval methods, the level should be monitored at approximately 4-hour intervals or less."
32
o
\\l Not'e from Table!5 that Commonwealth Edison proposes an alternative position on this item. CE Submittal'No. 2 states the following:-
" Leakage vill be monitored at approximately four hour.
1 tervals; a small interval tolerance vill avoid technical specification violations while still maintaining a conservative surveillance interval."
3.2.4 Definition of Unidentified Leakane Generic Letter 88-01 states:
" Unidentified lenkage should include all. leakage other than:'(a) leakage into closed systems, such as pump neal or. valve packing leaks that art captured, flow metered, i
and conducted to a sump or collection tank, or (b) leakage I
into the containment atmosphere from sources that are both specifically located and known either not to '
,.g a
interfere with.the operations of unidentified leakage monitoring systems or not to be from a throughwall crack
_i i
in the piping within the reactor coolant pressure boundary."
As indicated in Table 5, the Quad Cities 1 Technical Specification conforms with this position. CE Submittal' No. 1 contains the following clarifying remark:
"Ir.dividual identified leakage is not flow-metered, but
- . +
-all identified leakage is collected and conducted to L
a separate collection system from unidentified leakage.
Total identified leakage is monitored via the drywell
)
equipment drain sump pump discharge flow totalizer ester."
l 33
- }
e p,
l 3.2.5 Operability of Monitorina Instruments l
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."
As indicated in Table 5, the Quad Cities 1 Technical Specification will be amer.ded to include this requirement.
3.2.6 Evaluation and Recommendations Commonwealth Edison's position concerning compliance with Regulatory Guide 1.45 is dicta'ted by limitations of plant facilities, so acceptance of this position is recommended.
Commonwealth Edison's positions concerning limits on the total unidentified leakage of 5 gpm, description (or definition) of unidentified leakage, and operability of leakage monitoring instruments are in-compliance (or will be changed to.be in compliance) with the NRC Staff positions.
Thus, acceptance of these positions.are recommended.
. 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 required 34 l
I
.g,.
q o
, j. '
\\
in Generic Letter 88-01. Thus, rejection of this position is recommended. Commonwealth Edison should amend the Quad Cities 1 Technical Specification to limit the increase of unidentifie' 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 j
F over the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average).
3.3 Welds Excluded from IGSCC Pronram
.-I 1
3.3.1 Scope of Generic Letter 88-01 Generic Letter 88-01 defines the exter.t of its applicability i
as follows:
"This Generic Letter applies to all BWR piping made of
-l austenitic stainless steel that is four inches or Isrger j
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 su'ch as jet pump instrumentation penetration assemblies and head spray f
L' and vent components."
u 3.3.2 Commonwealth Edison's Position i
In response to a question in a Request for Additional I
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 1 included all ASME Code class 1, 2, 3 piping welds made of austenitic stainless steel that 35
i
.L
.f 4
L?
- f. q 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 becaose they were considered to be outside the defined. scope of Generic IAtter 86-
- 01. The phrase 'regardless of Code classification' used in Generic Letter 83-01 (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 I
isolation valve are NON-ASME Code and Non-safety related."
L; 3.3.3 Evaluation and Recommendation L'
j i
1 Commonwealth Edison has incorrectly interpreted the scope of welds covered by Generic Letter 88-01. The phrase,
]
l "regardless of Code classification" means that neither code related nor non-code related welds should be excluded unlest they are excluded by the size or temperature requirements.
Thus, rejection of Commonwealth Edison's position is
]
recommended.
It is-further recommended that Commonwealth L
Edison should revise their.IGSCC program to include the RWCU
\\,
welds that are downstream of the isolation valves that are 1
4 inches or larger in diameter and operate at temperatures above 200*F.
p i.-
l I
36 i
j' 1
l'.
- 4. CONCLUSIONS AND RECOHKCKDATIONS Concerning the thirteen NRC Staff positions as delineated in Generic Commonwealth Edison endorses most of the thirteen NRC Letter 88-01:
Staf f 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 distr'ibution resulting from stress improvement would be incorporated in calculations for stress improved welds). In addition, Commonwealth Edison proposed alternatives to some of the provisions outlined in Generic Letter 88-01 pertaining to leaksge detection.
Commonwealth Edison excluded certain welds from their ICSCC 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 8B-01 (i.e., that the scope is restricted to code related piping) was the basis for that omission.
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 1 with the result that most welds that are inboard of the isolation valves have received some form of mitigating treatment. A weld-by-weld list in one submittal (designated as CE Submittal No. 2 in this report) which gives weld histories and inspection histories shows that velds were correctly classified into the various IGSCC categories except for one overlayed weld (No. 02J-S4) which is classified as IGSCC Category E This weld should even though it contains a defect in the overlay.
be classified as IGSCC Category F.
In the assignment of the IGSOC classifications to welds between castings and between castings and carbon steel piping, Commonwealth Edison interpteted the guidelines of Generic Letter 88-01 to apply to IGSCC Category A classifications 37 I I l lll
1 to these welds even though they contain > 0.035% carbon. This interpretation is within the NRC Staff guidelines as delineated in Generic Letter 88-01.
)
Another submittel (designated as CE Submittal No. 3 in this report) indicates classifications of IGSCC Category A for two of the welds classified as IGSCC Category D in CE Submittal No. 2.
No explanation 1
l for this discrepancy was provided. Since their inspection program-performed in the 1989 Refueling Outage were based on the CE Submittal L
No. 3.
It is not possible to determine from the information provided whether the two welds involved should have been inspected during the 1989 Refueling outage or whether they were inspected during that outage.
The current veld population and the number of welds assigned to each t
I of the IGSCC categories as provided by Commonwealth Edison is based E
on an updated version of the veld population as summarized in CE l
l i
l Submittal No. 3.
The updating accounted for extensive piping
]
l replacement, piping removal, stress improvement treatments, and repair of weld overlays that were performed during the 1989 Refueling Outage.
The current list, which was provided only in summary form, shows that only 42 of a total of 235 welds remain unmittigated.
It also shows l
that all of the unmitigated welds have been inspected at least once.
Other actions planned for mitigating IGSCC are the use of Hydrogen k'ater Chemistry and replacement and/or repair of welds (using NPC Staff approved processes) as needed.
An Inservice Inspection program (ISI) has been developed for Quad Cities l
1 which, accordfrg to the CE Sub-ittals, follows the guidelines of l
inspection requirements of Generic Letter 88-01 pertaining to schedule, methods and personnel, sample expansion, reporting of flaws, and plans for inaccessible welds. The inApections performed during the 1989 Refueling Outage complied with the NRC Staff guidelines as delineated in Generic Letter 88-01 with the possible exception of the two welds mentioned above that may have been incorrectly classified as IGSCC 38 l.
l-t I-l
\\
1 Category A rather than ICSCC Category D.
No inspections are planned for the next refueling outsge, which is acceptable per guidelines provided in Generic letter 88-01 for IGSCC Categories A, C D, and E, but this does not satisfy the requirements for IGSCC Category F welds which should be inspected during every refueling outage.
Thr. austenitic stainless steel piping systems at Quad Cities 1 contain f.:r velds that are inaccessible for UT inspection. Two of these welds i
Visual are IGSCC Category A, and the other two are IGSCC Category G.
inspection for one of the inaccessible IGSCC Category G welds is planned. No plan currently exists for the other IGSCC Category G weld 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 i
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 schedules, methods and personnel, and sample expansion. Rather they Such action proposed to include such a statement in the ISI Program.
was specifically rejected in Generic Letter 88-01.
The Quad Cities 1 Technical Specification contains (or vill be changed to contain) the provisions recommended by the NRC Staff pertaining to limits on the total unidentified leakage of 5 spm, descriptions (or definition) of unidentified Icakage, and operability of leakage monitoring instruments. Commonwealth presented an alternative proposal concerning frequency of leakage measurements (i.e., that they will 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). Although this position was presented as an alternative position, it is actually within the of the NRC Staff guidelines.
Commonwealth Edison proposed two other alternative positions concerning 39 r
,.~
a leakage detection (1) Concerning the NRC Staff position on lialting any increase of unidentified leakage to 2 spm during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period 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. Thin is unacceptable because it is less restrictive than the NRC Staff position.
(2) Deviations from strict compliance with some items in 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.
(1) Rejection of Commonwealth Edison's position which excludes welds 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 1 (including inspection l
schedules) to include this portion of piping.
(2) Acceptance of Commonwealth Edison's IGSCC classifications of welds at Quad Cities 1 that are inboard of the isolation valves except for veld 02J-S4 (currently classified as IGSCC Category E) and the two welds (not identified by weld number) which are classified as IGSCC Category D in one submittal and IGSCC Category A in another submittel.
k' eld 02J-S4 should be reclassified as IGSCC Category F, and action should be taken by Commonwealth Edison to eliminate the discrepancy between the two submittals concerning the number of IGSCC Category D and IGSCC Category A welds.
l (3) Acceptance of Commonwealth Edison's position on inspection i
schedules for welds at Quad Cities 1 that are classified as IGSCC Categories A, C, D, and E.
(4) Rejection of Commonwealth Edison's position on inspection schedules for IGSCC Category F.
These welds should be scheduled 40 l
j' for inspection during every refueling outsge until they qualify for refueling outage as directed in NUREG 0313 Revision 2 and Generic Letter 88-01.
(5) Acceptance of Commonwealth Edison's plan for visual inspection of one of the two inaccessible welds that are not scheduled for replacement.
(6) Rejection of Commonwealth Edison's position concerning the second of the two inaccessible welds that are not scheduled A plan should be formuisted and pursued to for replacement.
ensure the integrity of this weld untti it is determined that it is or is not within the scope of Generic Letter 88-01 (i.e.,
whether or not the operating temperature is < 200'F).
(7) 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.
I (8) Rejection of Commonwealth Edison's position concerning The limitations of an increase of unidentified 1(akage.
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 increase in rate of unidentified leakage in excess of 2 gpm or 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 /> averago as proposed by Commonwealth Edison).
(9) Acceptance of other portions of Commonwealth Edison's position on leakage detection.
(10) Acceptance of the remaining portions of the CE Submittals.
41
l, 4
- 5. REFERENCES l
1.
" Technical report on Material Selection and Processing Guidelines i
for BWR Coolant Pressure Boundary Piping," KUREG 0313 Revision
- 2. U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation, January, 1988.
)
lnvestigation and Evaluation of Stress-Corrosion Cracking in Piping
'i 2.
of Light k'ater Reactor Plants," KUREG 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. Nucle st Regulatory Commission, January
?
25, 1988, t
4 42 i
l
.gr Appendix A Weld History and Classification of 4-Inch Diameter Welds in Head Spray Head Vent, and CRD at Quad Cities 1 IGSCC Material System Weld No.
Caten.
_1st Comp. Weld 2nd Comp.
Treatment CRD 03-F9 A
C-Steel NC Cast S.S.
none CRD 03-F7 D
NC NC NC none CRD 03-F8 D
NC NC Cast S.S.
none Head Vent N7-S2 D
NC NC NC none Head Spray 10HS-F10 D
NC NC NC none Head Spray 10HS-F10A D
NC NC NC none Head Spray 10HS-F11 D
NC NC Cast S.S.
none Head Spray 10HS-F12 D
Cast S.S.
NC NC none Head Spray 10HS-F9 D
NC NC NC none Head Spray 10HS-S1 D
NC NC NC none Head Spray 10HS-SIA D
NC NC NC none Head Spray 10HS-S2 D
NC NC NC none Head Spray 10HS-S3 D
NC NC NC none Head Spray 10HS-S5 D
NC NC NC none Head Spray IQHS-S6 D
NC NC NC none Head Spray 10HS-S7 D
NC NC NC none CRD 03-F6 G
NC NC NC none Head Vent 10HV-F1 G
NC NC NC none Head Vent N7-S1 G
NC NC NC none Head Spray 10HS-SS G
NC NC NC none i
Summary of 4-Inch Diameter Welds CE Submittal No. 2 No. of 4-Inch No. of Velds of System Dia. Velds Caten. A Caten. D Caten. G CRD 4
1 2
1 Head Vent 3
0 1
2 Head Spray 13 0
12 1
Total' 20 1
15 4
CE Submittal No. 3 Total 20 3
13 4
Abbreviations: NC indicates that material in non-conforming.
Cast S.S. is cast cast stainless steel with C > 0.035%.
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A-1 l
1 J
4 e
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