IR 05000334/1989019
| ML19354D558 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 12/20/1989 |
| From: | Strosnider J, Winters R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML19354D557 | List: |
| References | |
| 50-334-89-19, NUDOCS 8912280024 | |
| Download: ML19354D558 (10) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Report No.
50-334/89-19 Docket No.
50-334 License No.
DPR-66 Licensee:
Duquesne Light Company Robinson Plaza Building No. 2 Suite #210, PA Route 60 Pittsburgh, Pennsylvania 15205 Facility Name:
Beaver Valley Power Station, Unit 1 Inspection At: Shippingport, Pennsylvania In3pection Dates: October 30 - November 3, 1989 Inspector:
} E la D R. W. Winters, ' Reactor Engineer, MPS, EB, date DRS, Region I
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Approved by:
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f 'trosnider, Chief, Materials & Processes date S tion, Engineering Branch, DRS, RI
. Inspection Summary: A routine unannounced inspection was performed from October 30 to November 3, 1989 (Report No. 50-334/89-19). The inservice inspection, steam generator eddy current, and erosion corrosion programs were-inspected.
Information on water quality and control was gathered.
Results: No violations or deviations were identified.
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DETAILS 1.0 Persons Contacted Duquesne Light Company
- J. O. Crockett, General Manager, Corporate Nuclear Services
- K. D. Grada, Manager, Nuclear Safety
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- G. A. Kammerdeiner, Director, Materials and Standards Engineering
- F. J. Lipchick, Senior Licensing Supervisor
- R. A. Perry, Supervisor NDE Services
- B. F. Sepelak, Licensing Engineer
- W. H. Sikorski, Director, ISI
- N. R. Tonet, Manager, Nuclear Engineering
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United States Nuclear Regulatory Commission
- J. E. Beall, Senior Resident Inspector
- Denotes those attending the exit meeting, The inspector also contacted other administrative and technical personnel during the inspection.
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2.0 Introduction The Beaver Valley Power Station, Unit 1 is a three loop Westinghouse designed pressurized water reactor plant designed for a rated output of 2,660 MWt.
The plant was licensed for commercial operation on January 30, 1976. The steam generators are vertical shell, U-bend, Westinghouse Model.51. The inservice inspection program is in the first period of the second interval.
The 1983 Edition including the Summer 1983 Addenda is the applicable ASME Code for this inspection interval.
3.0 References / Requirements Technical Specification - Steam Generators paragraph 3.4.5 Final Safety Analysis Report - Steam Generators paragraph 4.2.2.4 PWR Secondary Water Chemistry Guidelines - Electric Power Research Institute Special Report, EPRI NP-2704-SR ASME Boiler and Pressure Vessel Code,Section XI, 1983 Edition, Summer 1983 Addenda
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4.0 Steam Generator Eddy Current Inspection Scope The inspector reviewed eddy current examination data from past outages, the data collected during the 1989 outage, and the system used to assure adequate data analysis.
Results of Prior Irapection During the inspection in 1988, 100% of the active tubes in all three steam generators were inspected. The number of tubes plugged and the cause is shown in Table 1.
TABLE 1 TUBES PLUGGED DURING 1988 INSPECTION Steam Generator
"A"
"B"
"C" Suspected IGSCC
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2 Antivibration Bar Wear
5 Cold Leg Thinning in Support Plate
3
U-Bend Defects
10
Foreign Object Damage 1(1)
Total 1988 Inspection
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Total Plugged in Generator
36
(1) Short piece of welding electrode 1989 Inspection Scope The inspector reviewed the results of the 1989 inspection and discussed these results with cognizant personnel. The planned Technical Specification examination was 100% full length bobbin coil of all active tubes ?n the
"B" steam generator except for rows 1 and 2 in the U-bend region. The U-bend region of rows 1 and 2 was examined by rotating pancake coil (RPC)
techniques. The results of these examinations placed the steam generator in the 'C-3' category and the inspection was expanded to 100% of all tubes in steam generators "A" and "C".
Examinations were performed as shown in Table 2.
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- TABLE 2 EXAMINATIONS PERFORMED IN STEAM GENERATORS Examination Steam Generator
'A'
1B1
'C'
100% Bobbin Coil except U-bend rows 1 and 2 X
X X
RPC of U-bend rows 1 and 2 X
X X
RPC of all Distorted Signal Indications X
X X
RPC of all hot leg B&W plugs (1)
X(1) (1)
RPC of cold leg B&W plugs accessible from one manipulator position X
X X
Tubes affected by loose parts removal X
Verify type of existing plugs X
X X
Review data for loose parts X
X RPC 148 tubes at top of tubesheet for cracks X
RPC of 44 tubes expanded in 1986 X
Re-exam of tubes from U-bend stress relief X
(1) All B&W plugs were replaced due to cracking.
Results The results of these inspections are summarized in Table 3.
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TABLE 3 RESULTS OF 1989 INSPECTION Steam Generator
'A'
'B'
'C'
Total Tubes to Inspect 3309 3352 3360 Tubes Inspected 3309 3352 3360 Indications 40-100% through wall (1)
39
Indications 20-39% through wall (1)
115
Indications less than 20% through wall (1)
46
?3 Distorted Signal Indications (1)
411 179 168 Total Tubes Plugged
49
(1) A tube may have more than one indication.
At the time of this inspection the failure mechanisms had not been determined.
The history of these steam generators indicates that the degradation of the steam generator tubes is increasing at an accelerating rate. Table 4 shows the plugging history for the last three inspections.
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TABLE 4 PLUGGING HISTORY
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Total Tubes Plugged Steam Generator
'A'
'B'
'C'
After 1986 Inspection
16
After 1988 Inspection
36
After 1989 Inspection 165
47 It should be noted that the increasing rate can, in part, be attributed to the improvement in eddy current inspection and analysis techniques. From these data it also appears that the three steam generators are not responding the same to the plant environmental conditions since steam generator 'C'
has only about one third of the number of plugged tubes that 'A'
has.
' Data Analysis The inspector reviewed the licensee's Eddy Current Analysis Guidelines, ISI-GL-004A, Revision 0 to determine that these guidelines were adequate for providing the data analysts with information to assure all data was properly analyzed. These guidelines provided the analysts with sufficient information to provide continuity between th_e organizations performing the analysis (Babcock and Wilcox and Echoram) and to assure that differences were resolved in a conservative manner. The guidelines also assured that the nomenclature used'by both organizations was the same thus elimiriating differences from this source.
Data analysis was performed by two independent analysts, the first by auto-matic data screening (ADS) a computer technique with a certified analyst reviewing all indications identified by the computer, the second by an analyst reviewing all data.
Differences were resolved by the Level III analysts from both organizations.
In no case could the severity of an indication be reduced from pluggable to not pluggable by a single individual.
Conclusions The licensee recognizes the starting of a trend toward more rapid deteriora-tion of the steam generators and is attempting to understand the cause of this trend and mitigate the results.
Replacement of the B&W plugs was done to prevent cracking and leakage during plant operation.
The overall inspection was in excess of the regulatory requirements. Data analysis was performed using a redundant system to assure that no indications were missed. One of these systems was a computer analysis backed by certified analysts. This technique has been proven in the industry as effective in reducing the time required for analysis while enhancing the accuracy of the analysis.
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5.0 Inservice Inspection Scope The inservice inspection (ISI) program was reviewed to determine if the licensee is on schedule for completing the required inspections in accordance with the ASME Boiler and Pressure Vessel Code,Section XI and with the schedule for the 1989 outage.
Details of the Review The licensee is committed to the ASME Code,Section XI,1983 Edition, Summer 1983 Addenda and is in the first period of the second interval at Beaver Valley, Unit 1.
The ISI program, incorporatesSection XI requirements of subsections IWB, IWC, IWD, and IWF for class 1, class 2 and class 3 systems and for component supports respectively.
ISI of the steam generator tubes is conducted in accordance with the units Technical Specifications and is a separate program designed for steam generator inspection.
The inspector reviewed the qualification program of the major ISI contractor.
This contractor was Ebasco Services Company.
The Ebasco certification procedure, NDE-1, Revision 12, Training, Examination, and Certification of Nondestructive Examination Personnel, was reviewed and found acceptable.
The inspector reviewed the certifications for selected personnel and determined that these individuals had been properly examined and certified in accordance with this procedure.
The inspector interviewed cognizant personnel and reviewed the results of the ISI program to determine if the required inspections for the first period were on schedule. The licensee maintains a computer tabulation of the status of the inspections performed under the program. This tabulation is updated by the contractor as testing is completed and verified by the licensee when the results of testing are reviewed. The licensee retains the authority to substitute components to be inspected when plant condition require and the ASME Code-allows such substitutions.
As a result of this review the intpector determined that the licensee had performed or has scheduled the required inspections for the current outage.
Conclusions The qualification and certification of the contractor personnel was acceptable and there was suitable evidence of licensee review of these certifications. The ten year program for ISI was on schedule for the first period of the second interval.
Some acceptable changes in the original schedule had been made to adjust the specific component inspections to plant condition.,
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6.0 Water Chemistry Control Scope Water chemistry data were reviewed as part of this staar generator inspection and maintenance inspection. The methods of collectir.g and verifying the accuracy of these data were not included in the scope of this inspection.
Details of the Review
.The inspector interviewed cognizant personnel and discussed the control of primary and secondary water chemistry in the plant systems.
The results of the controls for the secondary water chemistry were also reviewed for the current calendar year.
The results of the secondary side water chemistry control are shown in Table 5.
The Chemistry Performance Index (CPI) is a weighted average of the five principal corrosion causing impurities concentrations in the secondary system divided by the EPRI upper specification limits. Thi s-i s-.
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9 ant per.f.ncmance=indicatore TABLE 5 SECONDARY CHEMICAL RESULTS 1989 Month Blowdown Monthly YTD
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Cation Sodium Chloride Sulfate Oxygen CPI CPI January 0 33 1.4 1.8 5.0 4.2 0.25 0.25 February 0.39 1.4 2.2 7.1 4.7 0.30 0.28 March 0.31 1.1 1.8 4.9 5.1 0.26 0.27 April 6.28 1.2 2.8 4.9 5.0 0.26 0.27 May 0.30 1.0 2.1 5.4 4.8 0.26 0.27 June 0.34 1.2 1.6 5.5 4.5 0.26 0.27 July 0.29 0.8 2.5 5.4 4.5 0.24 0.26 August 0.29 0.7 2.1 2.6 4.3 0.21 0.25 September (Shutdown for Refueling)
(Values in parts per Billion except CPI has no units.)
Control of the pH in the secondary water system is based on Morpholine additions.
The licensee attempts to maintain the pH at approximately 9.3 to reduce erosion / corrosion, iron transport, and sludge in the steam generators. This has been successful since the plant has few components exhibiting erosion / corrosion degradation and virtually no sludge in the steam generators.
During cycle 7 the licensee controlled the lithium in the primary system at 2.2 parts per million until the pH rose to 7.4.
The lithium was then reduced to maintain this pH.
During the cycle there was a soluble release
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of cobalt that was caught in the deminerilizers and a substantial reduction of radiation fields throughout the system, (the steam generator channel head radiation field was reduced approximately 20%). This treatment is in accordance with EPRI guidelines.
Conclusions c
The licensee has maintained excellent control of both the primary and secondary water quality. This control has resulted in reducing the radiation fields through the primary systems. On the secondary side there has been little erosion / corrosion observed and the sludge in the stem generators has been reduced-to the point where lancing is not required.
7.0 Erosion - Corrosion Program The inspector reviewed the licensee's program ES-M-009, Revision 1, Erosion /
Corrosion Program for the Beaver Valley Power Stations Units #1 and #2, and discussed the erosion - corrosion control program with cognizant licensee personnel to determine the extent of the program and the results achieved.
The program includes approximately 32 components. A component is defined as a fitting, including the welds, and approximately six inches on each side.
Reproducibility of results is considered fair between outages due to very local-differences and the difficulty in exactly relocating prior inspection points.
The accuracy of the testing is estimated to be 8% of the wall thickness. The licensee has selected components in the following systems.for evaluation:
Condensate
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Heater Drains in the Recirculation System
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Moisture Separator Reheater Drains
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Extraction Steam Lines
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The feedwater recirculation lines were added to the program this outage.
In addition the licensee performed a visual examination of the interior of the crossover and crossunder lines this outage.
Conclusions The licensee has been very selective in determining components to be inspected.
The program provides good information about the general erosion - corrosion rates of the components chosen.
8.0 Cobalt Reduction Program Beaver Valley Unit 1 was used as a typical Westinghouse three loop plant in the EPRI study " Evaluation of Cobalt Sources in ' Westinghouse Designed Three and Four Loop Plants".
The results of this study are contained in EPRI Report NP-2681.
This report contains detailed data on Beaver Valley Unit I components.
Table 6-shows the average annual cobalt input into Beaver Valley Unit 1 from various sources as excerpted from this report.
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TABLE 6 l
Average Cobalt Input (Grams / Year) from Various Sources Component / System High Cobalt Alloys Other Alloys All Alloys Wear Corrosion Corrosion Total Percent Reactor Coolant 41.71 41.71 68.8
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Fuel Assemblies 0.94 0.94 1.6
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Main Coolant Pump 0.37 2.74 0.16 3.27 5.4 Reactor Vessel Int 0.23 0.42 1.04 1,69 2.8 CRDMS 1.80 2.71 0.27 4.78 7.9 Valves 3.93 1.45 5.38 8.9
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Loop Stop Valves 2.81 0.05 2.86 4.7
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Totel 60.63 From t'he-above table the EPRI study determined that more than 2/3 of the soluble cobalt was from the reactor coolant system, specifically from the Inconel steam generator tubing.
In the case of Inconel, cobalt is not considered an alloying element but is present as an impurity of the nickel alloying element.
Removal can only be accomplished by replacement of the steam generator tubes.
The inspector reviewed procedure ES-M-018, Revision 1, Engineering Activities in Support of the Transient Cobalt Control Program to determine what action the licensee has taken on the control of cobalt.
This procedure requires that engineering review each design change or plant modification involving valves or material in contact with the primary water system.
The procedure had only recently become effective and only two modifications had been reviewea.
The inspector determined that these reviews were adequate.
Conclusions The licensee has been aggressive in addressing the cobalt solution in the plant piping. A good investigation of the sources of the cobalt was made when the plant was part of the EPRI study, and the licensee has followed through by implementing a cobalt reduction program through engineering evaluation of modifications.
9.0 Management Meetings Licensee management was informed of the scope and purpose of the inspection at the entrance interview on October 30, 1989.
The findings of the inspection were discussed with licensee representatives during the course of the inspection and presented to licensee management at the November 3, 1989 exit interview.
(see paragraph 1 for attendees).
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i At no time during the inspection was written material provided to the
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licensee by the inspector.
The licensee did not indicate that proprietary information was involved within the scope of this inspection.
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