IR 05000369/1993004
| ML20036B125 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/27/1993 |
| From: | Blake J, Coley J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20036B119 | List: |
| References | |
| 50-369-93-04, 50-369-93-4, 50-370-93-04, 50-370-93-4, NUDOCS 9305180190 | |
| Download: ML20036B125 (10) | |
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Report Nos.:
50-369/93-04 and 50-370/93-04 Licensee: Duke Power Company 422 South Church Street Charlotte, NC 28242
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Docket Nos.: 50-369 and 50-370 License Nos.: NPF-9 and NPF-17
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Facility Name: McGuire 1 and 2 Inspection Conducted: April 12 - 16, 1993 Inspector: \\-s L/
,Q3-D u
J. L K oley Jr.
y Date Signed
3 Approved by:
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J. f. lak'e, Chief Date Signed Mate als and Processes Section Ing neering Branch Division of Reactor Safety l
SUMMARY l
Scope:
l This routine, announced inspection was conducted in the areas of inservice inspection (ISI) - observation of work and work activities (Unit 1) and review of completed data and evaluations (Units 1 and 2). The erosion / corrosion l
(E/C) programs for Units 1 and 2 were also reviewed to determine the
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effectiveness of the programs in identifying degradation caused by E/C.
Results:
In the areas inspected, violations or deviations were not identified. The inspector's observation of ultrasonic work activities revealed that examination personnel were knowledgeable of the examination methods and indications identified during the examinations were recorded and evaluated as specified in the ISI procedures.
However, several weaknesses were also observed:
(1) ultrasonic examinations of stainless steel (SS) welds, conducted from one side only of the weld due to valve or component configuration, were not performed with refracted longitudinal wave transducers which could ensure sound wave penetration would be obtained through the weld material, (2) transducer certification was 9305180190 930513 PDR ADOCK 05000369 g
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missing for one transducer which had been used to examine the IB-Reactor i
Coolant Pump Flywheel, and (3) records of the flywheel examination indicated I
the wrong ultrasonic instrument was used.
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Two concerns were also addressed during the review of ultrasonic data and
evaluations: (1) previously identified defects on Weld No. IPZR-1, which is the lower head to shell weld on the pressurizer, were observed this outage to
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have multiplied in number and grown in both length and through-wall dimensions. These indications were being examined for the second time after fracture mechanic analysis, which accepted the indications in 1986 provided three consecutive period examinations revealed no defect growth. The licensee is presently manufacturing a sizing calibration block in order to conduct enhanced sizing examinations on the indications. The resolution of this evaluation including the identification of the mechanism which is producing the defects is essential in order that proper corrective action can be achieved by the licensee and the generic implication can be considered for other utilities. The inspector requested copies of the enhanced inspection results as well as the licensee's resolution of this problem as soon as it is available.
(2) Review of Unit 2 ultrasonic data for welds 2CF2FW-15-12 and
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2CF2FW-15-1 which are Feedwater/ Auxiliary-Feedwater pipe to nozzle welds revealed recorded indications which the inspector felt needed further evaluation by the licensee. These welds have a history of failure because of the thermal stratification of the cold auxiliary feedwater in the pipe with the hot feedwater when the plant is at Mode 3.
This problem was identified to licensees in NRC Bulletin 79-13.
The licensee's E/C program was found to be very effective for piping larger
than 2 inches. The program examines a large population of components of all sizes each outage and identifies a considerable amount of component degradation resulting from E/C.
In addition the licensee has a proactive pipe replacement program in order to reduce the amount of carbon steel piping susceptible to E/C.
Piping 2 inches and less had three (3) sealant cans
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installed on Unit I and two (2) installed on Unit 2.
However, the entire lines on the applicable systems are being replaced this outage for Unit I and
during the June 1993, outage for Unit 2.
The licensee was responsive to the inspector's identified weaknesses as well as to the concerns identified above. Actions to be taken by the licensee on these specific issues are delineated in paragraphs 2 and 3.
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REPORT DETAILS 1.
Persons Contacted Licensee Employees
- T. Foster, Mechanical Engineer
- E. Geddie, Station Manager
- L. Keith, Quality Assurance Technical Support
- L. Kunka, Compliance Engineer
- J. McArdle, ISI Level III Test Examiner
- T. McMeekin, Site Vice President
- D. Motes, Component Engineer
- J. Parker, Component Engineer
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- R. Pettit, Supervisor, Nondestructive Examination (NDE)
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- R. Sharpe, Manager, Regulatory Compliance l
- D. Silvers, Supervisor, Mechanical Maintenance
- D. Smith, Erosion / Corrosion Engineer
- G. Underwood, Quality Assurance Technical Support
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- J. Washam, Engineer, Safety Review Group p
Other licensee employees contacted during this inspection included craftsmen, engineers, and technicians.
Other Organizations
- R. Klein, Hartford Steam Boiler Code Inspector NRC Resident Inspectors
- K. VanDoorn, Senior Resident inspector T. Cooper, Resident Inspector
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- Attended exit interview
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Acronyms and initialisms used throughout this report are listed in the last paragraph.
2.
Inservice Inspection - Observation of Work and Work Activities Unit 1 (73753)
The licensee is currently in the first outage (Cycle 8) of the first 40-month period of the second 10-year inspection interval for Unit 1.
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applicable Code for this inspection interval is the 1986 Edition of ASME Section XI.
The inspector observed ultrasonic calibrations and examination activities for the welds listed below to determine whether ISI of pressure retaining components are performed in accordance with Technical Specifications, the applicable American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, correspondence between NRR and the licensee concerning relief requests, and requirements imposed by NRC/ industry initiatives.
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Welds examined were as follows:
Component / Weld ID item No.
Procedure No.
INIlF-261 005.011.146 NDE-601 Rev. O INI1F-262 B09.011.224 NDE-601 Rev. 0 INIIF-257 C05.011.138 NDE-601 Rev. 0 1RCP-1B Flywheel G01.001.002 NDE-901 Rev. O The inspector's observation of the above work activities revealed that the examination personnel were knowledgeable of the examination methods and indications were recorded and evaluated as specified in the ISI procedure.
However, weaknesses were identified by the inspector in the above
examination activities in that, during the one-sided (pipe to valve)
examinations of SS welds INIIF-261 and INIIF-262 the inspector noted
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that a 45' and a 60* shear wave transducer were used as directed by the approved nondestructive examination (NDE) procedure. Although the ASME B&PV Code does not specify the mode of sound wave propagation when i
examining SS weld material, industry research has concluded that in
order to consistently ensure proper penetration of SS weld materials, a
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refracted longitudinal wave transducer should be used.
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The inspector held discussions with the licensee's Level III Test I
Examiner concerning this examination weakness and was informed that Duke
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is presently revising procedure NDE-601. The new revision will require i
that both the 45* and 60* transducers be refracted longitudinal wave when examining SS materials.
This revision is anticipated to complete
in time for the June 1993, Unit 2 outage. The inspector inquired as to why a field change could not be made to the procedure at this time so that Unit 1 SS welds would be examined using this enhanced technique.
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The licensee stated that, "there were only 12 welds left to examine this
outage. However, these welds would be reviewed to determine if there
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are any one-sided examinations left to be performed and if so, early
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implementation of the requirement would be considered."
i In addition to the above, during the inspector's review of equipment
certifications for the IB-Reactor Coolant Pump (RCP) Flywheel
examination, the inspector discovered that the ultrasonic instrument
serial number was incorrect and that, the licensee did not have equipment certifications for the transducer used in the 13' examination (S/N M20242). As corrective action the licensee confirmed which instrument had been used in the examination of the Flywheel and amended l
the examination reports to reflect the correct equipment. The licensee
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also contacted the transducer vendor to obtain a copy of the missing transducer certifications. At the conclusion of the inspector's visit
the vendor certification had not been received. The licensee however was in the process of performing an analysis on the transducer which could be maintained as the transducers official certification.
Within the areas examined, no violation or deviation was identified.
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3.
Review of Examination Data and Evaluations - Units 1 and 2 l
(73755)
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The inspector reviewed the reported data and evaluations listed below to
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determine whether the method and extent of examinations complied with the licensee's ISI program and applicable NDE procedure; whether ISI
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data files are complete and the data are within the previously-
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established acceptance criteria; and whether the licensee's oisposition
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of adverse findings and subsequent re-examination is consistent with l
regulatory requirements.
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Weld ID No.
Component Item No.
Method Size / Component l
INIIF-286 B09.Oll.213A PT 6" Dia.x.719"
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INIl-200-2 B09.011.224A PT 6" Dia.x.719" INI1F-262 B09.011.224A PT 6" Dia.x 719"
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IND26-4 C05.0ll.002A PT 18" Dia.x.375"
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INDIF-38 C05.011.003A PT 18" Dia.x.375" 1ND26-1 C05.011.004A PT 18" Dia.x.375" t
IND26-2 C05.011.005A PT 18" Dia.x.375" ICAIF-480 C05.051.002A MT 6" Dia.x.432" i
ISVIF-128 C05.051.251A MT 6" Dia.x.432"
IMCR-NC-506 F1.10.003-C VT Variable Spring Support IMCA-CA-415 F1.20.008-C VT Mechanical Shock Suppressor l
IMCA-ND-023 F1.20.155-C VT Variable Spring i
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Support
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IMCA-NI-006 F1.20.203-C VT Variable Spring j
Support
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IMCA-NI-NS-007 F1.20.253-C VT
_ Variable Spring
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Support l
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IMCA-RN-959 F1.20.451-C VT Mechanical Shock Suppressor i
IMCA-SM-12 F1.020.551-C VT Hydraulic Shock
Suppressor l
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Review of Recorded Data and Evaluations Continued Weld ID No.
Component Item No.
Method Size / Component IMCA-VQ-010 F1.20.651-C VT Hydraulic Shock Suppressor
ultrasonic indications on Unit 1 Pressurizer lower head to shell wel d.
This weld in still under evaluation, as delineated below.
Denotes Unit I and 2 recorded feedwater nozzle data obtained by
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the licensee during a preceding outage.
Pressurizer Lower Head to Shell Weld Indications.
I During the review of recorded data and evaluations, the inspector noted that UT of the pressurizer for Unit 1 (Weld No. IPZR-1 which is the lower head to shell weld) had previously identified eleven (11)
rejectable ultrasonic indications (one of which was surface connected)
l in 1986. These defects had been accepted by a fracture mechanics analysis, provided no indication of growth was observed for three consecutive periods.
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The indications were re-examined in 1989 with no apparent growth, however, during the present outage the weld was examined again. Although the present test is considerably less sensitive than the previous two examinations, (for reasons which the licensee is presently trying to identify) nineteen (19) rejectable indications, seven (7) of which are surface connected, have been tentatively identified. These indications indicate growth in defect length and in through-wall dimensions.
At the present time the only observed difference in the examination technique between the 1986 and 1989 examinations and the examinations being conducted at the present time is that indications are presently being evaluated at 20% DAC (distance amplitude curve) where previous examinations were evaluated at 50% and 100% DAC depending on the amplitude of the signal. This difference in evaluation levels however would be more than offset by the difference in test sensitivity for the 1993 examinations.
In addition to attempting to identify the difference in test sensitivity the licensee is also manufacturing a new sizing calibration block in order that tip diffraction sizing methods can be performed on the indications. This enhanced sizing method should provide a more precise measurement of the actual defect size.
The inspector requested that the licensee forward copies of their enhanced inspection data and the engineering resolution to Region II as soon as it becomes available. This data is needed for NRC to properly assess actions to be taken by the licensee and to determine if the conditions reported have generic implications for other utilities. The licensee's Level III Examiner agreed to keep Region II informed.
Feedwater nozzle indications.
A second concern was identified by the inspector as a result of reviewing previously completed records for Unit 2.
During this review of ultrasonic data for the combined feedwater and auxiliary feedwater system pipe elbow to steam generator nozzle welds the inspector noted that plotted indications in Weld Nos. 2CF2fW-15-1 and 2CF2fW-15-12 were seen from both sides of the weld and in some cases with different angle transducers. The evaluation of the indications concluded that they were caused by geometric reflectors on the inside surface of the pipe. The licensee's UT examiner had even used a WSY-70 supplemental refracted longitudinal wave transducer to make his evaluation. This possibly indicated that the examiner probably had experienced the same concern over the indications that the inspector had when reviewing the plotted indications on actual size sketches.
When a fatigue crack however can be reliably detected by UT from both sides of the weld, the crack generally runs straight up through the material. This characteristic also makes the crack a good candidate for radiographic examination. The welds involved (feedwater/ auxiliary feedwater piping to nozzles) also have a significant history for fatigue cracking failure due to thermal stratification of cold auxiliary
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feedwater in the pipe with the hot feedwater when the plant is in
operational mode 3.
This problem has been generically identified in NRC l
Bulletin 79-13. Therefore the inspector discussed his concern with the
licensee's Level III Examiner that the two welds be candidates for l
l radiographic examination during the next Unit 2 outage in June 1993.
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Radiography was also suggested as the method of supplemental examination l
l because NRC Bulletin 79-13 recommended this method. Using UT, even a l
WSY-70 transducer cannot always effectively see the tips of crack
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indications and geometric indications can be confused with cracks.
After reviewing the inspector's concern the licensee's Level III Examiner agreed that the welds would be re-examined in the June outage
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however, radiography would not be used because of flow directional vanes
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installed in the pipe elbow. The Level III stated however, that enough
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refracted longitudinal wave transducers of various angles would be used
to examine the weld that if the indications were the result of cracks
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they would know it.
l Other records reviewed by the inspector where found to be accurate and complete.
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Within the areas examined, no violation or deviation was identified.
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Evaluation of Erosion / Corrosion Monitoring Programs Effectiveness -
i Units 1 and 2 (49001)
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The inspector evaluated the licensee's Erosion / Corrosion program for effectiveness.
Previous NRC inspections had examined the programs in
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place to determine whether they were in accordance with commitments to NRC in Bulletin 87-01, Generic Letter 89-08 and accepted industry
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standards. This inspection focused on just how effective the programs l
were in detecting degradation caused by Erosion / Corrosion of carbon
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steel piping.
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In order to evaluate the programs' effectiveness the inspector held l
discussions with the licensee erosion / corrosion engineers; reviewed post
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outage reports for each unit from the end of cycle (EOC) 3 (1986) until
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the present (E0C-7, Units 1 and 2); reviewed sealants repair logs for repairs required during operation for the past 5 years; and reviewed l
marked up drawings of previous pipe replacements, pipe replacements i
planned for E0C-8, and inspection locations planned for EOC-8 for both l
units.
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The result of the above discussions and reviews revealed that the
licensee has a large inspection program for the examination of
components in systems susceptible to E/C (925 sites / unit).
Each outage t
the licensee selects between 100 and 252 sample locations of various i
pipe sizes to examine. These programs have been very successful in
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controlling E/C. However, a significant amount of E/C has been
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identified.
In addition the licensee has implemented a planned program l
of pipe replacement for each outage. The replacement program removes i
the susceptible carbon steel piping from high priority systems and
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replaces it with stainless steel piping that is not susceptible to E/C.
Duke's design engineering performs the system re-calculations resulting from the use of stainless steel as a replacement material.
Sealant repair logs revealed a rather high rate of sealant repairs on piping 2 inches in diameter and smaller last cycle for both units (3 repairs on Unit I and 2 repairs on Unit 2).
However, the licensee is presently replacing the components and associate piping during the present outage for Unit I and the June, 1993 outage for Unit 2.
The inspector concluded that the licensee has identified which systems and components are most susceptible to E/C. Therefore, as long as an adequate level of surveillance is maintained, E/C should be contained j
satisfactorily at the McGuire facility.
This conclusion was re-enforced I
recently when the licensee modelled and analyzed the most susceptible j
systems on Units 1 and 2 with the Electric Power Research Institute's (EPRI's) computerized E/C program CHECMATE. This program ranks the
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system components susceptibility to E/C. The licensee found that the
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sample they had selected for examination was also consistent to the CHECMATE selection.
Within the areas examined, no violation or deviation was identified.
5.
Exit Interview i
The inspection scope and results were summarized on April 16, 1993, with
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those persons indicated in paragraph I.
The inspector described the
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areas inspected and discussed in detail the inspection results.
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Proprietary information is not contained in this report.
Dissenting
comments were not received from the licensee.
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6.
Acronyms and Initialisms
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American Society of Mechanical Engineers B&PV
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Boiler and Pressure Vessel
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Auxiliary feedwater System
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Feedwater System l
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Distance Amplitude Curve
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Diameter
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E/C
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Erosion / Corrosion i
E0C
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End of Cycle
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ID
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Identification
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Inservice Inspection
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Magnetic Testing i
ND
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Residual Heat Removal System
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Safety Injection l
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NRC
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Nuclear Regulatory Commission l
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Penetrant Testing l
PZR
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Pressurizer t
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Reactor Coolant Pump RT
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Radiographic Testing
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Refracted Longitudinal Wave Transducer l
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Stainless Steel-
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SV Main Steam Vent to Atmosphere
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Ultrasonic Testing
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Visual Testing j
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