ML20069Q290
| ML20069Q290 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 12/01/1982 |
| From: | Rausch T COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| REF-SSINS-6820 5496N, NUDOCS 8212080537 | |
| Download: ML20069Q290 (10) | |
Text
Commonwealth Edison G
One First National Plaza, Chictgo. lilanois O'
Addrzss Riply to: Post Office Box 767 Chicago, Illinois 60690 December 1,1982 Mr. James G. Keppler, Regional Administrator Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Dresden Station Unit 2 Quad Cities Station Unit 1 Response to I.E. Bulletin 82-0 3 ( Re v. 1)
NRC Docket Nos. 50-237 and 50-254 Re ference (a):
R. C. DeYoung letters to All Licensees dated October 14 and 28, 1982.
Dear Mr. Keppler:
Re ference (a) transmitted I.E.Bulletin 82-03 which addresses stress corrosion cracking in thick-wall, la rge diameter stainless steel recirculation system piping at BWR plants.
The Commonwealth Edison Company response to this bulletin for the applicable units, Dresden Unit 2 and Quad Cities Unit 1, is provided in the attachment to this letter.
Note that because Quad Cities Unit 1 is nearing completion of the current refueling outage, all o f the bulletin items are addressed.
The Dresden 2 response only addresses bulletin item 4; the remaining information will be provided prior to startup from the spring 1983 refueling outage.
To the best o f my knowledge and belief the statements con-tained herein and in the attachment are true and correct.
In some respects these statements are not based on my personal knowledge but upon information furnished by other Commonwealth Edison employees and consultants.
Such information has been reviewed in accordance with Company practice and I believe it to be reliable.
Please address any questions you may have concerning this matter to this office.
8212080537 821201 PDR ADOCK 05000237 G
,C g
]
amave Gaag.tauwp) at40 DP2P wttt euq
J. G. Keppler Decem'oer 1, 1982 One (1) original copy of this letter and a copy of the attachment (minus the color coded drawings) is also being provided to the Document Control Desk as requested.
Very truly yours, W
Thomas J.
ausch Nuclear Licensing Administrator 1m Attachment cc:
Region III Inspector - Dresden Region III Inspector - Quad Cities USNRC Document Control Desk, Washington, D.C.
20555 SUBSCRIBED and SWORN to beforg me this /.44 day of dV -t u m <_ /t ro, 19 82 MAS A ^
er-v
~
Notary Public 5496N
3
~
~lt 5
s
\\
?
s, ATT AC HMEN T Ns d
.l -
COMMONWEALTH EDISON
\\
'A DRESDEN UNIT 2 AND QUAD CITIES UNIT 1 a,
RESPONSE TO I.E. BULLETIN 82-03 REV. 1
'l M
s ITEM 2: i ResQlts of Recirculation System' Inspections T Applicable to Quad Cities 1 only)
~ ~.
T a
x A total of 9 cbtcomferential welds on recirculation piping f
1 Were ultrasonically incpected during this 1982. refueling
, outage.
e 3'
1 s Tne results 'o fi th,ese UT' inspections are tabulated in Table R-1.
s s
s, ITEN 3:
Corrective Actions (
( Applicsble to" Load Cities 1 only) 3 s i x1 N
No u.ardsolvable indications which would require corrective.
'f5 t ion's. ~w ere,i de h ti fie d.
~
x 4
4 ITEM 4.a:
Inspehtiob Sampling Pla n Ni 4.a.1:
Qu mi Ci tie s.1 :
c---
I[dmetric drawings o f Quad Cities Unit I recirculation
, ;[,,
system, ISI-l'0 3-sheet s - 1 through 4, identify all recirculation piping. welds that have been examined
,1 ultrasonically during this refueling outage.
These wejds are circled in red with the corresponding stress l5 \\ JS rule index (SRI) alue.
Also identified in ISI-105 v
sheets 2 and 3 are the RHR system piping welds which 3; j
'e're examined with their SRI values.
4 4.'a. I ': s Dresden 2:
3-s, w
1.-
't i
i A't tached a re isomqtric drawings ISI-103 sheets 1, 2,
\\di ' arm 3 which indicate the welds previously examined and h[_'
-tys weJ_ds;to 'De cidnine'd during the next refueling 77 i'
i s Ni,!
d-cu,t' age.._,. 3 gs
_f o,
s Ws shown40. thest drawings, eleven welds will be
,I
,,.-)N dtl5pected' 35 thd edeirculatid'n system plus the twelve i
,' Y s
' f l furnace senyttized safe end to piping welds, for a total o f 25 weld ~s.
We are.also considering
' inspections o,ftlarge diamdter welds in the' shutdown i
cooling synf.em and LPCI system which attaches to the recirculatiori system.
The results of these inspec-tionj~-wr],T'bd reported with the recirculation system
~
results in our response to item 2 of the bulletin.
e 4
4 tt
.g
, "c s
tr M I
. 4.a.2:
Sample Selection Method (Quad Cities 1 and Dresden 2)
The weld sample selection plans employed at Quad Cities Unit 1 and to be applied to Dresden Unit 2 were focused on weld joints considered to be relatively more susceptible to intergranular stress corrosion cracking (IGSCC).
Stress Rule Index (SRI) calcula-tions were utilized as the primary input to the selection process.
These calculations were performed by different organizations for the two stations and due to somewha t different methodology, the range of actual SRI numbers is lower for Quad Cities Unit 1 than for Dresden Unit 2.
We have utilized the SRI numbers for relative ranking of welds by stress and not for discriminating between welds believed to be above or below some IGSCC threshold.
The carbon content of the piping material was not factored into the selection process.
Presentations by General Electric indicated relatively little dif fer-ence in IGSCC susceptibility for carbon contents of 0.05 percent or higher.
A survey of carbon content at Dresden Unit 2 and a search at Quad Cities Unit 1 showed essentially all welds in the recirculation system to be 0.05 percent or greater carbon content.
Although I.E. Bulletin 82-0 3, Rev. 1 indicated "la rge bore" recirculation piping to be the item of interest, we have for completeness included the sampling plans for recirculation riser lines in our responses.
In addition, portions o f the large diameter branch lines to the recirculation system were included due to their being non-flowing and having high calcuated SRI numbers.
(These branch lines were included at Quad Cites 1 as noted in Table R-3 and shown in drawings ISI-105 sheets 2 and 3 of 3; we are considering similar inspection at Dresden Unit 2).
The SRI numbers for the selected welds are shown on the enclosed isometric drawings.
The weld sampling plans in general consist of the highest SRI numbers for each o f the diameters of piping in the recirculation system and for portions of the large diameter branch lines.
Due to radiation ALARA concerns and in the interest o f distributing the sample, a few exceptions o f the above were made.
All o f the welds selected have SRI numbers ranking at o r nea r the nighes t for the location o f interest.
., 2 4.a.3:
Piping Materials Quad Cities 1 Material type, diameter (nominal), and wall thickness of inspected welds are provided in Table R-1.
Dresden 2 All pipe material is type 304 12" diameter Sch 80 with minimum wall of.585 22" diameter with minimum wall o f.979 28" diameter suction with minimum walls of 1.113 28" diameter discha rge with minimum wall o f 1.267 4.a.4:
Radiation Exposure Estimates Quad Cities 1 The recirculation system contact dose rates are R
R generally found to be in the 1 /hr to 3 /hr range.
A conservative estimate of total occurpational radiation exposure incurred is 94.1 man-rem.
Th e following conditions have assisted in lowering the radiation exposure of personnel involved in. insulation services, weld preparation, and weld inspection.
1.
The use of lead shielding (lead blankets) on inspected piping and/or nearby piping whenever possible.
2.
Three welds selected for inspection did not require grinding since they had been inspected once previously.
This, in e f fect, significantly lowered the radiation exposure incurred to weld preparation personnel.
Dresden 2 Tne following is the number of welds to be inspected at the next outage using Item Aa. as a basis and the estimated occupational radiation exposure projected for NDE inspectors only:
12" diameter - 4 welds - 1.2 m-rem 22" diameter - 3 welds - 2.16 m-rem 28" diameter - 4 welds - 2.88 m-rem Totals - 11 welds - 6.24 m-rem (NDE Inspectors) 4
~
. 4.a.4:
Radiation Exposure Estimates Dresden 2 (Cont'd)
The estimated occupational radiation exposure projected to remove and install insulation in order to inspect the above welds is 6R.
An additional 2.5 man rem is estimated to perform weld preparation, yielding a total o f approximately 14.7 5 man-rem.
This total does not include any exposure incurred in performing the twelve furnace sensitized safe end inspections which is estimated to require 12 man-rem for the NDE personnel and 60 man-rem to remove and install insulation (no weld preparation is required for these weld s).
Total projected exposure for recirculation weld inspection, preparation, and insulation is there fore about 8 6.7 5 man-rem.
Following are some ALARA measures that will be implemented:
a)
Shielding installed when practical.
L)
Use o f master slave system proposed by Lambert, McGill and Thomas (NDE contractor who will be used this outage).
c)
Pre-job planning.
4.b UT Summary Description (Quad Cities 1 and Dresden 2)
The UT procedure used at Quad Cities Unit 1 and to be used at Dresden Unit 2 require that calibration sensitivity be set on side-drilled holes which provide greater sensitivity than is obtained using ASME XI Appendix III notches.
Scanning is pe rformed at a minimum o f 6dB above calibration sensitivity.
Evaluation and measurement is required of any indication that is 50 percent or more of the calibration level.
Any indication considered to be a crack is evaluated and measured regardless o f amplitude.
Tne calibration standards used at Quad Cities Unit 1 were all Type 304 stainless steel with the following descriptions:
Piping Diameter Curved or Flat Thickness 28" Flat 1.361" 22" Flat 1.087" 20" Fla t 0.840" 16" Cu rved 0.722" 12" Curved 0.585"
. 4.c Previous Recirculation System Inspection Results (Quad Cities 1 and Dresden 2)
Dresden Unit 2 will utilize the same calibration standards for the 16" and 12" diameter piping.
The 28" and 22" diameter piping examinations will utilize curved block standards as required by the ISI program for the second 10 year interval'
( ASME XI 1977 Edition through Summer 1979 Addenda).
As previously noted, calibration will be set from side drilled holes.
The results of previous Quad Cities Unit 1 recirculation piping weld inspection are tabulated in Table R-2.
Th e Dresden 2 previous inspections are indicated in the attached isometrics.
For both units, any detected recordable indications were evaluated as geometry, and at no time was a repai r deemed necessary.
Please note that welds examined earlier in the interval utilized earlier revisions o f the CECO procedure.
The earlier revisions were essentially the same in technique, standards and recording, and as such the results should be valid.
- 4. d Crack Detection Capability Evaluation (Quad Cities 1 and Dresden 2)
The ef fecL.veness o f the Commonwealth Edison (CECO) procedure in detecting service induced intergranular stress corrosion cracking (IGSCC) was demonstrated by CECO personnel at Battelle Memorial Institute (BMI) on flawed samples from the Nine Mile Point Unit 1 plant.
A sample of flawed Nine Mile Point 28" piping was utilized at Quad Cities Unit 1 and will also be utilized at Dresden Unit 2.
The CECO personnel who demon-strated the UT procedure at BMI completely characterized the i
flaws in the weld joint.
All contractor personnel performing UT examinations of large bore stainless steel piping at Quad Cities Unit 1 were required to demonstrate their ability to correctly find the flaws prior to performing examinations.
CECO personnel reviewed all contractor data reports and performed resolution examinations as required.
A similar qualification of contractor UT personnel will be performed at Dresden Unit 2.
The diameters and thicknesses of the piping examined at Quad Cities Unit 1 and to be examined at Dresden Unit 2 are contained in section 4.a.3 of this report.
The piping welds were made using counterbcres and consumable inserts and generally have convex ID weld root geometries.
l 5496N
TABLE R-1 RECIRC WELDS EXRMINED THIS OUTAGE (dall 1982)
Weld Weld Material Nom.
Wall Identification Configuration Specification Diam.
Thickness Inspection Results OD Geometry - finger dampened 02BS-FG TEE /
A403-304
'28" 1.113 Min Valve A351-CF8M ID Root Geometry - 20% D.A.C.
Indications confirmed by CECO ID Root Geometry - noted for 360 02BS-F7 Valve /
A351-CF8M 28" 1.113 Min Pipe A358-304 at higher gain Indications confirmed by CECO OD Geometry - finger dampened 02A-59 Pipe /
A358-304 22" 1.048 Min:
g CAP A403-304 ID Root Geometry - noted for 360 Indications confirmed by CECO
~
02B-F5 Cross /
A403-304 22" 1.048 Min
- No recordable indications Pipe A358-304 02G-F2 SE/
^
35 04 b
5 n
Pipe 02F-F2 02E-F2
}
q
'f
- O.D. Geometry 02L-F2
'P v
02BS-F2 SE/
SA376-316 28" 1.831 Min' Elbow In Geometry - noted for 360 A403-304 l.267 Min intermittently I,
ID Geometry - mismatch This weld was examined using L.M.T.s.
procedure UT-10 and CECO's procedure NDT-C-2, Rev. 12.
(Rev. 7) g Y
9 h
TABLE R-2 RECIRC UELDS EXAMINED IN PREVIOUS OUTAGES Weld Identification Size Inspect.
Procedure Results Date 02AS-S1 NOZ-SE 28" May 74 C-2 Rev.
4 No recordable indications 02AS-F2 SE-P May 74 C-2 Rev.
4 No recordable indications 02DS-F2 SE-P Jan 79 C-2 Rev. 10 I.D. Geometry 02BS-F6 TEE-V Feb 76 C-2 Rev. 10 No recordable indications 02BS-F7 V-P Feb 76 C-2 Rev. 10 I.D.
Root & Counterbore Geometry 02BS-S9 P-E 1r Feb 76 C-2 Rev. 10 I.D. Root 02A-F1 V-P 22" Feb 76 C-2 Rev. 10 No recordable indications 02-Fl P-V Feb 76 C-2 Rev. 10 No recordable indications Feb 76 C-2 Rev. 10 No recordable. indications 02-F2 P-V 02C-F2 SE-P 12" May 74 C-2 Rev.
4 No recordable indications 02D-F2 SE-P May 74 C-2 Rev.
4 No recordable indications 02G-S3 P-E Feb 76:
C-2 Rev. 10 I.D. Counterbore & OD Crown Configuration 02G-S4 E-P Feb 76 C-2 Rev. 10 I.D. Root & Counterbore 02G-F6 P-Sweep Feb 76 C-2 Rev. 10 No recordable indications 02K-F2 SE-P Jan 79 C-2 Rev. 10 No recordable indications 02C-Fl NOZ-SE May 74' C-2 Rev.
4 No recordable indications 02D-Fl NOZ-SE V
May 74 C-2 Rev.
4 No recordable indications
TABLE R-3 INSPECTION RESULTS OF RHRS PIPING (LPCI AND SHUTDOWN COOLING) 4 Weld Wall ASTM. Mate Nom.
Wall Inspection Configuration Specification Si.ze
. Thickness Inspection Results 10S-Fl TEE A403-WP304 I
Pipe A358-TP304 20" 0.840 Min No recordable indications 10S-F5 Pipe A358-TP304 20" I.D. Geometry - 360 intermittent jValve A351-CF8M counterbore geometry.
10S-F6 Valve!
A351-CF8M Pipe A358-TP304 20"-
I.D.
Geometry - 360 intermittent.
counterbore geometry 10AD-Fl TEE A403-WP304
!Pipe A358-TP304 16"'
O.722 Min'.
No recordable indications 10AD-F4 Elbow A403-WP304 16"I No recordable indications jValve A351-CF8M 10AD-F5 Valve!
A351-CF8M Pipe A358-TP304 16 '.'
ID Root Geometry - 3600 intermittent 10AD-F13 Valve A 3 51-CF8'1 16"-
No recordable indications j
~
Pipe A358-TP304 i
10BD-Fl TEE A403-WP304
!Pipe A358-TP304 16"!
No recordable indications i
10BD-F5 Elbow! alve A403-WP304 V
A351-CF8M 16"I No recordable indications 4
e s