IR 05000335/1991025
| ML17223B404 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 12/24/1991 |
| From: | Blake J, Glasman M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17223B403 | List: |
| References | |
| 50-335-91-25, 50-389-91-25, NUDOCS 9201170162 | |
| Download: ML17223B404 (12) | |
Text
'
AS AEQy
~o UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323 Report Nos.:
50-335/91-25'nd 50-389/91-25 Licensee:
Florida Power and Light Company 9250 West Flagler Street Miami, FL 33102 Docket Nos.:
50-335 and 50-389 License Nos.:
DPR-67 and NPF-16 Facility Name:
St. Lucie 1 and
Inspection Conducted:
o er 15-22, 1991 Inspector:
M. M.
Approved by:
J.
.
ake, Section Chief, Materia s
and r
esses Section E gineering Branch Division of Reactor Safety SUMMARY Dat Signed
'/z zf/ri ate
)gne Scope:
This routine, unannounced inspection was conducted onsite in the areas of Inservice Inspection ( ISI) includi,ng a review of Nondestructive Examination (NDE)
procedures, observation of ultrasonic (UT) examinations, and liquid penetrant (LP) examinations, and associated activities, and review of completed NDE examination results data.
Also, licensee activities pertaining to the November 6, 1991 discovery of two broken feedwater ring retaining U-bolts in the Unit 1 1-B steam generator, and loose parts retrieval efforts were observed.
Results:
'This review of the licensee's ISI inspection activities and procedures indicated that pro'cedures in use were well-written, personnel, were well-trained, qualified, and motivated.
Licensee management monitored performance of ISI work and reviewed results in a satisfactory manner, especially in the area of eddy current testing of the steam generators, where considerable management involvement was evident in the analysis of acquired
. eddy current test results.
Especially noteworthy in the steam generator inspection area was the licensee's defect trending program; a
10K sample of defects in active steam generator tubes was selected to monitor/trend growth an'd other changes as inspections progress.
The inspector found that Florida
-'9201i70l.62 911227-PDR ADOCK 05000335
'9 PDR J
e
Power and Light (FPL) procedures were employed= for all. NDE work observed, and all. contract NDE personnel were required to demonstrate proficiency, in the applicable NDE technique(s)
by passing FPL practical examinations.'
REPORT DETAILS Persons Contacted Licensee Employees Fulford, Materials Performance Manager Craig, Manager, Steam Generator Program
"
Wolf, Site Engineering Supervisor Mayhew, Inservice Inspection Coordinator Church, Chairman, ISEG Ware, Technical Training Supervisor Dyer, Supervisor, Maintenance guality Control Geiger, Vice President, Nuclear Assurance Englmeir, Site guality Manager Flowers, Mechanical Maintenance Engineering Motley, Supervisor, Code Programs Menocoal, Mechanical Maintenance Department Head Roberts, Nuclear.Engineering Burton, Operations Superintendent Cornell, Engineering, Juno Beach Khurana, Engineering, Juno Beach Joseph, Equipment Support and Inspections Lisenbey, Equipment Support and Inspections, Metallurgical Lab
- J
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Other licensee
'employees contacted during this inspection included engineers, technicians, and administrative personnel.
Other Organizations V. Looper, NDE Technology P. Lenz, Asea Brown Boveri/Combustion Engineering NRC Resident Inspectors
- S. Elrod, Senior Resident Inspector
- M. Scott, Resident Inspector
- Attended exit interview Inservice Inspection - Observation of Work and Wo'rk Activities (73753)
t The inspector examined documents, activities, and records as indicated below to determine whether ISI was being conducted in, accordance with applicable procedures, regulatory requirements and licensee commitments.
The applicable Code for Unit 1 is the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME B&PV),Section XI, 1983 edition with addenda through Summer 1983.
The applicable Code for Unit 2 is the ASME B&PV Code,Section XI, 1980 edition with addenda through
Winter 1980.
The current Unit 1 ISI is being conducted in accordance with the licensee's second ten year interval ISI,plan.
C a.
. All NDE examinations in Unit 1 were being conducted.for the licensee by Ebasco with exception of the steam generator.eddy 'current (EC)-
examinations, which were conducted by Asea Brown Boveri/Combustion Engineering (ABB/CE),
NDE Technology, Zetek, and FPL personnel.
All contract NDE Personnel (as well as FPL NDE personnel)
were under the supervision of FPL, and had to demonstrate proficiency by passing FPL-administered practical examinations in the applicable NDE methods, and all NDE work was accomplished.using FPL procedures.
-b.
The inspector observed the in-process UT examinations being conducted on the welds listed below.
The observations were compared with the applicabl'e procedures and the Code in the following areas:
availability of and compliance with approved UT procedure and application to the examination being conducted; scan technique; type of couplant used; proper transducer and shoe; scanning level and reference level; indication recording technique;.time interval and
.
sequence of calibrations performed; and qualifications of personnel performing the examination.
Weld Number Descri tion MS-1FW-2 PRZ-C2 Main Feedwater, Circ.
Seam Pressurizer,'ower Shell to Lower Head Spectrum analysis and transducer performance data for the following ultrasonic transducers were also reviewed:
Ultrasonic Transducers Manufacturer/Model'erial No.
Aerotech, 3/4" Round, 2.25mHz Aerotech, 1/2" x 1" Re'ct.,
2.25mHz Aerotech, 1/2" x 1" Rect.,
2.25mHz K23705 J27831 F21933 c ~
The inspector observed the visible dye penetrant (PT) examinations listed below in the following areas; specified method, penetrant materials identified; penetrant materials analyzed for halogens and sulfur; acceptable pre-examination surface; drying time; method of penetrant application; penetration time; surface temperature solvent removal; dry surface prior to developing; type of developer, examination technique; evaluation technique; reporting of examination results, and the qualifications of the inspector performing the examinatio e Weld Number Descri tion d.'I-208-1-SW-3,
=
HPSI Pump lA to Header lA SI-208-I-SW-4
'PSI Pump lA to'Header 1A The inspector reviewed the qualification
'documentation for the following NDE Personnel to determine if certifications were current and in conformance with applicable licensee procedures and the Code.
Method-Level
~Com an Ebasco Ebasco Ebasco Zetec Zetec Zetec NDE-T ABB/CE ABB/CE ABB/CE Examine PK CP SC KS
,
WG MK VL PL RS GB UT PT MT EC II II II III III III II II IIIA IIIA IIIA IIIA I
I IA.
III VT II-I II-1,2,3,4 II-I e.
'Acquisition and analysis of Steam Generator EC data was conducted under the supervision of the FPL Steam Generator Eddy Current Test Coordinator.
EC data acquisition was conducted by ABB/CE.
The examination of the Unit I steam generators ( I-'A, and 1-B) consisted of a tubesheet-to-tubesheet bobbin coil examination on all active tubes, and motorized rotating pancake coil examination (MRPC) of all hot leg side tubes one inch below and two inches above the
"expansion" transition.
MRPC examinations were also performed on a
large number of flaws of interest detected by bobbin coil examination, to further confirm presence of a
flaw and/or characterize known flaws.
In addition, a loose parts scan was conducted on the periphery of the tube bundle in each steam generator.
Raw data was stored on magnetic tape on the Zetek MIZ-18A multifrequency system.
This data was later transferred to optical disk and subjected to primary and secondary analysis.
Primary analysis of bobbin coil examination data was conducted by analys'ts from FPL, Zetek, ABB/CE and NDE Technology.
A computerized secondary analysis was performed on the Eddynet version of the Zetek Computer Data Screening (CDS) system.
Discrepancies between results of primary. and secondary analyses were resolved by Lead Analysts.
Results of MRPC examinations were not evaluated by the CDS system.
The total number of steam generator tubes plugged and stabilized this outage are summarized below.
Criteria for tube plugging was detected degradation equal to 40Ã of tube wall thickness or greater.
Tubes were stabilized if circumferential cracking was detected at the
top of the tube sheet to prevent potential damage to adjacent tubes sliould complete breakage occur.
Steam Generator No. Tubes Plu ed No. Tubes Staked 1-A 1-B 285 (358 indications)
165 (189 indications)
82, Hot Leg 17, Hot Leg Including the above plugged tubes, the 1-A steam generator now has-12K of its tubes plugged and the 1-B steam generator has 8X of its tubes plugged.
The licensee's current Loss of Coolant Accident analysis.limits each steam generator to a
maximum of 15K plugged tubes with no more than a
7Ã differential between steam generators.
f.
The licensee has initiated a program to -track and trend the growth of identified defects in their steam generator
tubes.
A 10% sample of tubes containing indications from 20K up to 39K were selected for study.
One anticipated benefit of this study will be to help predict the best interval for steam generator replacement, in addition to the knowledge that will be gained by studying the 'growth of indications while subjected to an actual operating environment.
Results 'will be made available as the data becomes available.
3.,
Review of NDE Procedures, Units 1, and 2 (73052)
The inspector reviewed the procedures indi'cated below to determine whether they were consistent with regulatory requirements and licensee commitments.
The procedures where also reviewed in the areas of procedure approval, requirements for qualification of NDE personnel, and compilation of required records, and, when applicable, division of responsibility between the licensee and contractor organizations/personnel involved in ISI inspection.
'a ~
The ultrasonic procedure was reviewed to ascertain if it -was, reviewed and approved in accordance with the licensee's established gA procedures.
The procedure was also reviewed for technical adequacy and conformance with AMSE,Section V, Article 5 and other license commi.tments and requirements in the following areas:
type of apparatus used; extent of coverage; calibration requirements; search units; beam.angles DAC curves; reference level for monitoring discontinuities; method for demonstrating penetrations; limits for evaluation of recording of indications, and acceptance limits.
b.
The inspector
'reviewed the EC procedure for technical content relative to:
multichannel examination unit; multichannel examination indication equipment is specified; examination equipment is specified; calibration standard and calibration sequence is specified; material permeability is accounted for, and acceptance criteria are specifie c ~
The inspector reviewed the Liquid Penetrant (PT)
procedure to determine if it was reviewed and approved in accordance with the licensee'
es'tablished gA procedures.
The
. procedure was also reviewed for technical adequacy and conformance.with ASME,Section V,
Article 6,, and other licensee commitments/requirements
.in the following areas:
specified method; penetrant material identification; penetrant materials analyzed for, total halogens; acceptable pre-examination, surface drying time; acceptable; dye penetrant, dwell time and removal technique; acceptable
'developer dwell time, and
- proper lighting and viewing aids.
~
'DE 1.3 R.4 Eddy Current Examination of Non-Ferromagnetic'ubing With Multi-Frequency Techniques.MIZ-18A NDE 5.1 R.6
'Ultrasonic Examination of Pressure Vessel Welds, Except Reactor*Vessels NDE 3.3 R.3 Liquid Penetrant Examination Solvent Removable Visible Dye Technique The above
.procedures were found to be comprehensive, and satiCfactory.
4.
Inservice Inspection, Data Review and Evaluation, Unit 1 (73755)
Records of completed steam generator eddy current examinations indicated below were reviewed and compared with the applicable procedures and the Code in the following areas:
the multi-channel eddy current examination equipment
'was identified; material permeability was reco'rded; method of examination was recorded; calibration intervals were recorded; examiner(s)
were recorded, defects and defective tubes were identified, and results were consistent with acceptance criteria.
a.
The inspector randomly selected a
number of tubes, listed below, inspected by the licensee and independently verified obtained
,
results, including the validity of resolutions performed when primary and secondary analyses differed.
- Tubes selected for evaluation by
'he inspector included those containing indications greater than 39K, less than 39K, and tubes requiring resolution by lead analysts.
- Steam Generator 1-A Bobbin Coil Data Row Line Indication Location'is osition
50
49
49
,
89
01 Hot Leg 01 Cold Leg 06 Hot Leg 02 Hot Leg 03 Cold Leg 525, Plug Not Reportable Not Reportable 138 Through Wall 21% Through Wall
Row Line
'= ~cont'~d 106
106
73
57
53
'81 61 '3
83
84
84
84
83 Indication Location 01 Hot Leg 09 Hot Leg 02 Hot Leg 01 Hot Leg 03 Hot Leg 04 Hot Leg Vert.. Support
Vert'. Support
Tube Sheet Hot 05 Hot Leg'ube Sheet Hot 43K, Plug 195 Through Wall 26K Through Wall Enter In Data Base Enter In Data Base No Detectable Degradation No Detectable Degradation 16% Through Wall 62K Through Wall, Plug No Detectable Degradation 16Ã Through Wall Steam Generator 1-A MRPC Data Row Line Indication Location'is osition b.
84 6.47" Above T.S..
60Ã Axial Indication, Plug
136 '1 Hot Leg
45K Axial Indication, Plug
~
137 02 Hot Leg 61% Axial Indication,. Plug
146 08 Hot Leg 61% Axial Indication, Plug Based on a
review of the above data-and discussions held with acquisition personnel, analysts, lead analysts, and FPL personnel, the inspector. concluded that the eddy current examination of the steam generators was conducted in a
satisfactory manner by knowledgeable, well-qualified personnel.
Judgements on questionable indications were made in the conservative direction, and it was evident that the licensee had devoted considerable resources to this inspection effort, both in personnel, and modern, up-to-date equipment.
5.
Damaged Feedwater Ring in Steam Generator 1-B On November 6, 1991, during routine outage-related visual examination of steam generator 1-B, the licensee found that the feedwater ring had shifted position several inches, and that two of four feedwater ring retaining U-bolts were broken.
In addition, the two remaining U-bolts were= bent, however, they were not broken and were able to hold the feedwater ring in place.
The U-bolts; fabricated from SA-306 Grade
steel, were 3/4" diameter, and were held in place with double-nutted 3/4-10 nuts.
The failures were just above the nuts, and all four pieces were recovered after the conclusion of this inspection.
The licensee performed a failure analysis on one of the two broken U-bolts, dated November 12, 1991, and based on the presence-of a
well-formed and tightly adherent oxide layer on the fracture surfaces, concluded that the failures had not taken place recently; it was not
possible to determine the exact time of failure basedon this information alone.
In add'ition, the report stated that both legs on the U-bolt were subjected to a combination of tensile and shear loading, and that both sides of the U-bolt experienced 'similar loading.
Further, the appearance of the fracture surfaces suggested ductile failure had'aken place and that the origin of the fracture appeared to be subsurface.
Based on the direction of bending, deformation of the bolt'ends, and the appearance of the fracture surface,. the licensee concluded that movement of the feedwater ring was the cause of the U-bolt failures.
This failure analysis report was reviewed by the inspector, and found to be thoro'ugh, and the inspector agreed with the conclusions therein.
The inspector held discussions with cognizant licensee technical staff and they indicated that the 1;B steam generator was subjected to a visual inspection conducted in February 1990,
'during the previous outage, by Combustion Engineering.
This report indicated that three U-bolts in steam generator 1-B were loose, however, no other abnormal conditions were found.
Based. on the results of the February 1990 inspection, the damage must have taken place afterwards, and based on the information available,
'he licensee's preliminary conclusion was that several water hammer events caused -the damage.
This, per cognizant licensee personnel, is likely because of a leaking flushing drain plug at the bottom of the feedwater ring in the I-B steam generator.
Upon loss of main feedwater flow and until. initiation of auxiliary feedwater flow, a sufficient volume of water could have leaked from the feedwater ring through the leaking flushing drain plug to cause a water hammer occurrence to take place.
These flushing drain plugs were installed during a previous (1976) modification in which the original feedwater -ring was equipped with J-tubes; the flusihg drains
'were used to flush debris following construction.
At the time of the inspection, the licensee conducted a similar inspection of the I-A steam generator, with special attention focused on the condition of the feedwater ring retaining U-bolts and integrity of the flushing drain plugs; no abnormalities were found.
The licensee also reviewed results of previous inspections and did not find a history of loose U-bolts or flushing drain plug staybolts in the I-A steam generator.
The licensee indicated that the steam generators in Unit 2 were originally designed with a top feed (J-tube)
feedwater ring, and there were no drains or other sources of unanticipated leakage from the feedwater ring.
In addition, the Unit 2 steam generator feedwater ring is restrained by two U-bolts per restraint instead of one, as in the previous Unit I design.
The licensee plans to repair the damage by using a U-bolt on each side of each mounting saddle. (instead of one U-bolt per saddle)
as in the Unit 2 steam generator design.
In addition, to avoid inducing unwanted stress in the feedwater ring, the licensee plans to elevate the mounting saddles to the resting position of the feedwater ring by shimming the mounting saddles; about I/2 inch of shimming was required.
The damaged flushing drain plug will be removed and a patch wi 11 be welded over the hole.
The remaining plug was.intact, and due to ALARA considerations, may not be remove.
Exit Interview The inspection scope. and results were-summarized on November 22, 1991,'ith those persons indicated in paragraph 1.
The inspectors described the areas inspected and discussed in detail the inspection results.
Proprietary information is not contained in this report.
Dissenting comments were not received from the licensee.
7:
Initialisms and ASME B&PV Code ABB/CE DAC EC FPSL ISI MRPC MT NDE NDE-T
"NRC NRR PT QA UT VT Acronyms American Society of.Mechanical Engineers Boiler and
'
Pressure Vessel Code Asea Brown Boveri/Combusion Engineering Distance - Amplitude Curve Eddy Current Testing
'lorida Power and Light'nservice Inspection Motorized Rotating Pancake Coil-Magnetic Particle Testing Nondestructive Examination NDE Technology Nuclear Regulatory Commission
. Office of Nuclear Reactor Regulation Liquid Penetrant Testing
'uality Assurance Ultrasonic Testing Visual Examination