IR 05000295/1992008
| ML20198D543 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/18/1992 |
| From: | Jeffrey Jacobson, Ward K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20198D527 | List: |
| References | |
| 50-295-92-08, 50-295-92-8, NUDOCS 9205210069 | |
| Download: ML20198D543 (8) | |
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U.S.
NUCLEAR REGULATORY COMMISSION-
REGION III
g Report No.:
50-295/92008(DRS)
Docket No.:
50-295 License No. DPR-39 Licensee:
Commonwealth Edison Company Opus West III 1400 Opus Place Downers Grove, IL 60515 Facility Name:
Zion Station - Unit 1 Inspection At:
Zion Site, Zion, IL Inspection Conducted:
March 23-24, 30-31, April 1,
9-10, 24, and May 12, 1992 Inspector:
d f/[7/9'L_
]K.
D.. Ward Date Accompanied By:
K. Karwoski,.NRR B.
Metrow, IDNS (March-23-24, 30-31, April 1,
9-10, 24, and-Mcy 12, 1992)
C.
pd, ORNL-Approved B OtJ., h k M @ -i 1L-
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J J /M 3acoyson, Chief'
Date
,M5te al,V & Processes Section
%s Insoection Summary Inspection on March 23-24. 30-31. April 1.
9-10.
24. and May 12.
1992 (Recort No. 50-295/92008(DRS))
Areas Inspected:
Routine, unannounced safety inspection of inservice inspection (ISI) activities including review of programs (73051), data (73755), procedures (73052), observation of work. activities (73753), and review of the erosion / corrosion (E/C) program (73051, 73052, 73753, and 73755).
An independent inspection of the steam generator eddy current examination was performed by NRR with contract assistance from ORNL and is attached to this report.
Results:
No violations or deviations were identified.
Based on the results of the inspection, the NRC inspector noted the following:
The licensee adequately demonstrated the ability to properly implement the ISI program, including the eddy current examinations of the steam generator tubes.
9205210069 920518 PDR ADOCK 05000295 O
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'-Inspection-Summary
Personnel involved in'the ISI' effort appeared knowledgeable,
well' trained, and competent.-
Management was involved in the ISI activities in an
effective manner,
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-DETAILS 1.
Persons Contacted Commenwealth Edison Company (CECO)
- D.
Wozniak, Technical Superintendent
- D.
Bump, Nuclear: Quality Programs Superintendent
- R.
Chrzanowski, Regulatory Assurance Supervisor
- E.
Robey, ISI Group Leader
- R.
Tolentino, ISI Engineer
- K.
Dickerson, Regulatory Assurance Engineer T.
Cook, ET Engineer G. Svendson, E/C Engineer U.S.
Nuclear Requlatory Commission (NRC)
- A.
Bongiovanni, Resident-Inspector J.
Hickman, Project Manager, NRR J.
Smith, Senior Resident Inspector R..Leemon, Resident Inspector K.
Karwoski, Material Engineer, NRR C.
Dodd, NRC Consultant, Eddy Current Examinations Illinois Department of Nuclear Safety (IDNS)
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Metrow, IDNS Engineer Combustion Enaineerino (CEL J.
Russel, Lead Level III Dynacon Systems, Inc. (DSI)
J.
Hayden,-Level-III Hartford Steam Boiler Inqn.qqtipn and Insurance Company (HSB)
D.
Oakley, ANII The NRCl inspector also contacted and interviewed other licensee and contractor employees.
- Denotes those precent during the exit interview on May 12, 1992.
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2.
Inservice Inspection (ISI) Unit 1 a.
Procram Review (73051)
l Personnel from DSI and CE performed the ISI in l
accordance with the licensee's program and ASME Section
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XI, 1980 Edition, Winter 1981 Addenda.
The licensee i
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did not--make a request for relief from the ASME Code for this outage.
The NRC inspector reviewed CECO's Nuclear Quality program Audits No.. 22-92-13, No. 22-92-07 and surveillances of ISI nrogram activities.
These audit efforts were found to va accepte51e and performed by qualified personnel.
Organizationa. staffing for the ISI program was found to be acceptable and the services of an Authorized Nuclear Inservice Inspector (ANII) were procured from Hartford Steam Boiler Inspection and Insurance Company.
b.
Procedure Review (73052)
All applicable ISI procedures were_ approved by the ANII and were reviewed by the NRC inspector.
The ISI procedures were found to be acceptable and in-accordance with ASME Section V, 1980 Edition, Winter 1981 Addenda, c.
Data Review (73755)
(1)
General The examination data was found to be in accordance with the applicable ISI procedures and ASME Code requirements.
The NRC inspector reviewed documents related to nondestructive examination equipment, data, and evaluations.
(2)
Eddy Current Examinations (ET)
During.this outage, 100% of all accessible tubes-were examined full length.
The examinations were conducted utilizing the Zetec MIZ-18 multifrequency digital test equipment with associated acquisition software and remote positioning devices.
The Zetec DDA-4 Digital Data _
Analysis System was used for the data evaluation.
Motorized rotating pancake coil (MRPC)
examinations were utilized to supplement the bobbin coil examinations.
The MRPC was used to further characterize crack depth, manufacturing burnish marks, undefined indications, and distorted indications.
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The following tubes were plugged as a result of the examinations:
Steam Total This Outaae Total All Outaaes
. Czenerator Ely1 qed Sleeved Pluaced Sleeved A
None 161 112 B
24 310 222 C
114 181 247 D
None 202
All of the new steam generator tube plugs were Inconel 690 alloy and the, installed welded sleeves were fabricated by CE.
Mr.
K. Karwoski, NRR, and Mr.
C.
Dodd, an NRC Eddy Current Examination'(ET) consultant, visited the Zion Station on March 30-31,-1992.
Mr. Dodd reviewed the ET program, procedures, data, and noted the absence of any outer diameter stress corrosion cracking at the t,ube support plates.
Steam generators of this vintage normally experience cracking of this nature.
It should be noted that the attached trip report (Enclosure 2) represents the views of the NRC consultant and not necessarily the views of the NRC.
(3)
MT was performed on 100% of the inside diameter of the upper shell to transition cone gicts weld on all four steam generators.
Indications >"re found in steam generators 1A, 1C, and 1D.
All who indications were ground out without going below
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minimum wall, blended, re-examined with MT, and found to be acceptable.
L Ultrasonic examinations were also performed on all four steam generator transition cone girth welds in'1989 (Reference Inspection Report No. 50-295/69028 (DRS) ).
d.
Observations of Work Activities (73753)
The NRC inspector observed work activities and had
discussions with personnel during the ISI activities.
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These observations included the following:
(1)
CE personnel performing eddy current examinations on the tubes in steam generators
"A",
"B",
"C",
and
"D".
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(2).
CE-personnel' evaluating eddy current examination data obtained from the steam generator tubes.
(3)
CE personnel performing mechanical tube plugging on steam generator "D",-using a TV camera in conjunction with_the use of video tape recorders to record the marking, wire brushing, sizing and plugging.
(4)
A CECO QA individual performing a surveillance on pipe welds No. CWE-1-4509-41, No.. CWE-1-4509-42 and No. CWE-2-22-00-12.
This effort includcd observing examinations and review of data.
(5)
ANII performing a surveillance on pipe. weld No.
CWE-2-22-0012.
This effort included observing examinations and review of data.
(6)
DSI personnel performing liquid penetrant examinations on pipe welds No. CWE-1-4509-41 and No. CWE-1-4509-42.
These welds were on the auxiliary spray system.
(7)
DSI-personnel performing magnetic particle examinations on pipe weld No. CWE-2-22-00-12.
This weld was on the main steam system.
(8)- DSI personnel performing visual examinations on valve bolts and hanger No. H26.
The items were on the1 auxiliary spray system..
(9)
DSI personnel performing ultrasonic examinations on pipe weld No. CWE-2-22-00-12.
This weld was on the main steam system.
The IDNS inspector also observed DSI personnel performing ultrasonic examinations on pipe welds No.
CWE-1-41-02-14, No. CWE-1-41-02-15 and No. CWE-1-41-02-16.
These welds were on the safety-injection system.
The-NRC inspector reviewed the qualifications and certificat1 ors of-all inspection personnel performing ISI to ensurt: conformance with SNT-TC-1A.
N~ violationsfor deviations were identified.
3.
Erosion / Corrosion Activities (73051, 73052, 73753, 73755)
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Commonwealth Edison Company began their erosion / corrosion j
(E/C) program in 1988.
A formalized procedure and b
administrative controls were established to ensure continued long-term implementation of the E/C monitoring program for
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piping-and components.
Thio program was applicable to both safety related and nonsafety related systems with respect to E/C.
Various references were used to establish the program, including NRC Bulletin No. 87-01, "Pf~s Wall Thinning" and EPRI-NP-3944, " Erosion / Corrosion-in
.c] ear Power Plant Steam-Piping."
An inspection sample is selected prior to every refueling outage utilizing the EPRI Chec, Checmate computer program.
This program considers such variables as the effects created by poor geometry, high fluid velocities, moisture content, temperature conditions, historical chemistry data and piping / component material.
When a piping component is found that has exhibited wall thinning due to E/C, an engineering analysis is performed.
This analysis determines if the degraded component is acceptable for continued use or if repair / replacement is required.
To date, there have been approximately 35' of 16" pipe replaced with chrome / moly material, and several elbows and tees as a result of the E/C-program.
The NRC inspector reviewed the program, procedures, data, and observed, in part, cutting and replacement of four feedwater regulating valve outlet expanders and approximately 45' of downstream piping.
The inspector also observed, in part, cutting and replacement of a 6" drain pipe in the extraction steam system.
Ultrasonic thickness examinations on pipe lines #37 and #39 on the condenser vent system were also observed.
No violations or deviations were identified.
4.
Modifications - Unit 1 (37701)
Replacement of Motor Driven Auxiliary Feedwater Discharae Check Valves. Mod. No. 722-1(21-89-015B The. auxiliary feedwater (AFW) pump discharge check valves have been the source-of operating and maintenance problems in the AFW system.
The previous valves permitted excessive back leakage to enter the AFW pump casing, raising thermal fatigue and stratification concerns.
Resolution of this problem involved the replacement of previously installed swing type check valves at'the discharge of the AFW pumps with new lift type check valves.
The piping design was in accordance with the ANSI B31.1 Code.
The preservice and inservice inspections were in accordance with ASME Section XI.
The NRC inspector reviewed the 10 CFR 50.59 safety evaluation, welding records, drawings, NDE records, including radiographs, and other related documentation.
The
. welds of two valves, No. 1FWOO32 and No. 1FWOO33 were
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visually examined by the NRC inspector and found to be acceptable.
No violations or deviations were' identified.
5.
Exit-Interview
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The NRC inspector met with_ licensee representatives (denoted in Paragraph _1) at the conclusion of the inspection and summarized the scope and findings of the inspection noted in this' report.
The NRC inspector also discussed the likely informational content of the inspection report with regard
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to documents or processes reviewed by the inspector during the inspection.. The licensee did not identify any such-
-documents / processes as proprietary.
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Poar emes ex wee OAK RlDGE NATIONA1. LABORATORY e^ moot, rswears cavero g7yn mem twm smews. c DC4 M u S DtPAR*1/lNT C# IWE*OY April 14,1992 Mr. Emmett L. Murphy Ofilce of Reactor Rcgulation Materials Engineering Branch U.S. Nuclear Regulatory Commission MS WFN 9H15 Washington, DC 20555
Dear Emmett:
On Merch 30,1992, I traveled to the Zion Nuclear Station Unit 1, North of Chicago, Illinois, nis plant, operated by C6inmoawealth Edison,is a 1098 MW clectrical plant and has four Westinghouse Model 51 Steam Generators. His plant went into operation in 1973, and the fint tubes were plugged in 1981.. is remarkable that no tubes were plugged until this late date. I meet Mtb Ken Karwoski of NRC/NRR, Kavin D. Ward of NRC Region IH, J. D. Smith, the h7C Resident Inspector and personnel from the utility and their contractors.
He generators have experienced small amounts of degiadation due to row one u. bend cracking, prirnary water stress corrosion cracking at the roll expansion, intergranular attack in the crevice region, and a pit like volumetric type of corrosion, mostlyin the cold tube support plates. De Model 51 generators have only 21/2 in. of the lower end of ihe tube rolled into the tube sheet, with the remainder of the 19 inches as a crevice. Hey have experienced the crevice corrosion problems to
- a small degree that other plants of this design have had. Very notable in its abaence is any outer diameter stress-corrosion cracking at the tube support plates. His is the first plant where this phenomenon has not been observed. All other plants have shown ODSCC in this region after about five years of operation.
De data were reviewed with the assistance of Jim Russel of ABB/ combustion and Tom Holden of Allen Nuclear Associates. Both of these analpts are well known in their fic!d and hold a level HI certification from their respective companies, although Tom Holden was performing level H analpis at Zion. During the course of the discussions,it was inentioned that there was a crucial shortage of peop!c qualified for level II data analysis.
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April 14,1992
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Emmett Murphy Inspection plan Tom Cook, the insenice inspection manager, reviewed the inspection plan with us.
All of the available unsleeved tubes were inspected fulllength with the 720 bobbin probe. Sleeved tubes were inspected with the cross. wound probe and with the 640 bobbin probe, not from cold leg around to sleeve with the 720 bobbin probe as is done in many sleeved tubes in other plants. A random sample of 25 tubes from each generator inspected in the row two u. bend with a rotating pancake probe (RPC) for cracking. De generators were inspected only from the het leg with the calibration standard hung on a specific tube in the cold leg. When the enlibration was due, the operator would run over to the tube with the standard and inspect it from the hot leg around to the standard hanging off of the cold leg. The in.line standard or the guide tube standard that is normally scanned with each tube inspected is missing from these tests. While this is not required by the code, some of the alternate plugging criteria proposals make use of the frequent standard scans.
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Revi w Data Analysis Guidelines. The data analpt guidelines were written by Steve Brown and, in general, were quite good. However, the history of the plant was sketchy in the guidelines and not well known by plant personnel This section of the gu J.:nes needs to be expanded. Here was a section on the detection of ODSCC at the tube supports in the guidelines, but the eddy-current scans showti in the guidelines were from other plants.
Calibration Review The calibration certificates on the MIZ 18's used ir, the inspection were resiewed and all appeared to be in date. I also reviewed the calibration standards and they appeared to be correct. The 101Gz differential signal showed the same distortion at the tube supports and ca!ibration ring; due to the magnetic bias and the higher pull speed Q4 ja per second) that other plants have shown. This distortion could impair the ability to mix out the suppott signals under some conditions. It is postulated that a combination of higher probe velocity, the ferromagnetism of the tube supports, and the magnetic bias of the permanent magnets is causing a 'back voltage" to be generated in the instrument.
Inspection Procedure Data is collected on magnetic tapes inside containment and manually transferred outside containment to the analpis trailer. There it is transferred to optical disks and analyzed using the Zetec EddyNet System. The data analyst inteniewed stated that the present implementation of EddyNet appears to be slower and without as many features as the Westinghouse data analysis system. He said that the Westinghouse software is also in color, which makes it easier
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05-!2-92.M:34Ak! IUM @)d MGM f(4
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Smmett Murphy
April 14,1992
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on the analyst eyes. The inspection procedure was written in 1999 before the use of EddyNet and has not been updated. We requested a new update of the prncedure be prepared for each outage, particularly if major changes are made.
ODSCC at The Tube Supports I reviewed 6everal tube supports and found no evidence of the ODSCC that has been observed at all ceher plants with a number of years operating experience. The data was also reviewed by Tom Holden of ANA, who has had experience at Trojan and other plants where this degradation mechanism is present. In Figure I we show a plot of the scan of a tube CDs e N case e tapose14.satet 3.04 0,79 sord F2-97 80 14 #38 33 Ctk to 5 j)g [.9 p!M
,,,4 L.we L): 16 lts 4-4
, is 42 33F7 3s 210 Sin 9: 100_ gTFT vvet Weet D.Sdd se 7 e 296 L,5dd es> 25 * 34 1.p/W em 27 * l?S b.sv/d op 4 e 212 9,
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a ipure 1 Lissajous Ugures for the first hot leg tube support for tube row 3 column 94
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I intersection from the Zion plant. "Itere is a straight transition on the 210KHz and the 100KHz signal that is somewhat similar to ODSCC at the tube supports. However, this signal is only 0.04 volts on i
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April 14,1992
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the mit, and decreases as the frequency increases, as a deposit would do. In addition, there is no l
transition on the strip chart representations that would represent a defect. Using the present criteria for calling ODSCC at other plants, this tube and the others I reviewed at Zion would be called "No Detectable Defecf.
Denting Zion 1 had only 75 dents that read 5 vo!ts or greater (on the 400KHz differential channel)
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in the 1989 data analysis in all 4 generators. A new procedure for handling the dents was being implemented at this outage. While part of t e new calibration was good, they were lowwing the h
reporting level by a factor of 20, which woun., m.inate the calling of any dents. At my request they agreed not to lower their dent calling threshold. I reviewed the present data analpt guidelines and did not notice the proposed reduction in dent reporting threshold. This plant has very little centing.
Magnetite in De Tube Suppon Cnmce There appears to be a small amount of corrosion of the tube supports, with very little accumulated magnetite in the tube support crevices. The amplitude of the 10 Khz differential signal on the tube supports L the generator is smaller than the araplitude of the signal on tbc calibration ring, which indicates the presence of some magnetite or the corrosion of the support plates.
Degradation Under ne Tube Supports A small number of tubes show mme sign of degradation under the tube supports, primarily under the cold leg tube supports. A bobbin trace of this type of defect is shown in Figure 2. It would be desirable to inspect these tubes from the cold leg with the RPC, but no inspections are being performed from the cold legs (the regular RPC probe will not pass around the u-bend). One tube support in the hot leg has shown a similar bobbin indication as the cold leg. A RPC trace of this defect is shown in Figure 3. This indication appears to be volumetric and pit like rather than crack like. It is very similar to the IGA signals observed under the tube i
supports at the St. Lucie plant in 1985. However, it is difficult to really tell conclusively unicss a tube were pulled.
L The utility has a database that will allow the inspection history of any tube to be displayed for any l.
tube that has been classified as having any type of defect or anomaly. Several tubes of this type were j
pulled up from the database. 'Iypically these defects were present at about the same size back in 1985. They may vary in measured depth by about 10% from inspection to inspection, which is typical
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April 14,1992
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Figurc 2 Scan of tube suppois 1 Hot of tube row 3, column 94 for a small signal under a tube support that is mixed. While some of them may exceed the plugging limit at q; inspection and have to be plugged, as a group they appear to be growing very slowly if at all.
Prima:y Water Stress Corrosiou Cracking PWSCC has appeared at the roll transition of a large number of plants. These exial defects are detected by loolting for a distortion of the bobbin signal as the probe passes through the roll expansion, which was detected on a small number of tubes at Zion 1. If the bobbin signal is distorted, a RFC scan is performed on this joint up to ebout 8 inches above the joint. The confirmation rate of the distorted bobbin signal with the RPC for this typ of
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defect is nearly d?0%.- Since the roll transition is only 21/2 in from the tube end, a tube could only leak in this region, but not rupture.
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Figure 3 KPC scan of tie first hot tube support of tube row 3 column 94 i
Degradation in De Tube-Sheet Crevice Intergranular attack (IGA) has been observed in the tube-sheet crevice region, similar to that in the crevice region in steam generators at Point Bev h and Ginna. De cracks are located and sized with the bobbin probe, and confirmed with the RPC, %ese cracks generally appear within 6 inches of the tube expansion region and are usually nearly through wall when they are detected, ney are well below the top of the tube sheet, and while they represent the potential for a small leak, they do not represent a threat of a tube rupture.
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April 14,1992 Emmett Murphy Fretting at he Activibration Bars ne utility has had a history of wear at the anthihra. ion ban (AVB). A special calibration curve has been generated for this particular problem and is being app.ied. Short segments of tubing have been removed from the generators to verify that the measurements are being made properly. This problem appean to be under control now.
Inspection Interval he utility technical specification calls for an inspection every 24 calendar months. De last inspection was performcd in Octoter of 1939, which makes the interval 29 calendar months. Ilowever, the utility is claiming that special requests have allowed the longer internl. This is being reviewed by the NRC.
Tube Pulls De utility has not pulled any tubes since the plant started operation in 1973. It may be prudent to pull a tube or two to verify the type ofdegradation mechanisms and identify any problems that are not being detected.
Recommendations The inspection being performed appears to be adequate for this outage.
However, basad on our findings, the following recommendations are made for the next outage:
1. He new method of calibrating for dents should be modified so that the reporting level is about the same as the previous one.
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2. A sampling of the problem areas with the RPC probe is very desirable. D e present inspection of the tubes with IGA in the crevice will provide a sampling of the roll transition region, and a slight extension (aiready made by ABB/ Combustion) sti provide a sampling of the crevice region corrosion problem. IIowever, a sampling of the tube support locations should be done to confirm that no ODSCC and no pit like IGA is being missed at these locations.
3. The utility uses Steve Brown as their level III cddy.eurtent consultant. While Steve is excellent, it would be advisable to develop an in house ine!III that can follow their inspecdons and problems on a day today basis.
4. Perform inspections of the sleeved tubes from the cold leg with a 720 bobbin probe. Also inspect the cold leg defect signals with a RPC to confirm that they are small, volumetric, and slow growing.
5. Pull a tube or two at the next outage to verify the type of degradation in the cold leg and to verify that there is no ODSCC in the bot leg.
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Emmett Murphy.
April 14,1992 6. Verify that the distortions on the scans of the tube support plates are causing no problems on the mix. Otherwise, the inspection speed should be lowered from 24 in/sec. to 12 in.kc.
7. His plant seems to have avoided the ODSCC that has been observed at all of the other plants with over 5 years of operating experience. The rest of the industry should find out what they are doing right and copy it.
Sin:erely yours, bk Caius V. Dodd Nondestructive Testing Group Metab and Ceramin DMsion
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cc:
L F. Blanker DOE!ORO A. M. Gill K. Karstaki D. J. McGuire
' J. Muscara D. G. O'Connor C E Pugh G. M. Slaughter C V. Dodd/ File
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