ML20148E701
| ML20148E701 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/10/1988 |
| From: | Blake J, Crowley B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20148E684 | List: |
| References | |
| 50-413-88-09, 50-413-88-9, 50-414-88-09, 50-414-88-9, NUDOCS 8803250281 | |
| Download: ML20148E701 (8) | |
See also: IR 05000413/1988009
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'['#CEGO
UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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101 MARIETTA GTREET.fi.W.
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ATLANTA, GEORGt A 30323
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Report Nos.:
50-413/88-09 and 50-414/88-09
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Licensee: Duke Power Company
422 South Church Street
Charlotte, NC 28242
Docket Nos.:
50-413 and 50-414
License Nos.:
Facility Name:
Catawba 1 and 2
Inspection Conducted:
February 2-4, 1988
E [. 8.
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Inspector:
ley
g
Date Signed
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Approved by:
v
J.
lake, Chief
Date Signed
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M er als and Processes Section
Q vi. ion of Reactor Safety
SUMMARY
Scope:
This routine, unannounced inspection was ir. the areas of steam
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generator tube problems (Unit 2).
Results: One violation was identified - Failure to Establish Adequate Measures
to Control ET Testing of Steam Generator Tubes
paragraph 5.a.
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REPORT DETAILS
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1.
Persons Contacted
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Licensee Employees
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- H. Cote', Licensing Engineer
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J. Hampton, Station Manager
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- R. Kaye, Nuclear Plant Specialist - Maintenance
- D. Mayes, Nuclear Production Engineer - Nuclear Maintenance
- W. McCollough, Mechanical Maintenance Engineer
T. Owen, Assistant Station Manager
- G. Smith, Superintendent of Maintenance
J. Willis, QA Station Manager
Other licensee employees contacted included engineers, QA personnel,
security force members, and office personnel.
NRC Resident Inspectors
P. VanDoorn, Senior Resident Inspector
- M. Lesser, Resident Inspector
- Attended exit interview
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2.
Exit Interview
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The inspection scope and findings were summarized on February 4,1988,
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with those persons indicated in paragraph 1.
The inspector described the
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areas inspected and discussed in detail the inspection findings.
No
dissenting comments were received from the licensee.
The following new
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item was identified during this inspection:
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(0 pen) Violation 414/88-09-01, Failure to Establish Adequate Measures to
Control ET Testing of Steam Generator Tubes
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T/.2 licensee did not identify as proprietary any of the material provided
to or reviewed by the inspectors during this inspection.
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3.
Licensee Action on Previous Enforcement Matters
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Thissubjectwasnotaddressedintheinspection.
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4.
Unresolved Items
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Unresolved Items were not identified during this inspection.
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5.
Inservice Inspection - Observation of Work and Work Activities (73753)
(Unit 2)
The inspector examined the activities described below relative to
inspection of steam generator 'S/G) tubes.
In accordance with Revision 2
of the inservice inspection (ISI) plan (submitted to the NRC on August 18,
1986), the applicable code is the ASME Boiler and Pressure Vessel Code,
Section XI,1980 Edition with Addenda through W81.
In addition, the
inspection sample size and acceptance criteria are specified in
Surveillance Requirements 4.4.5.0 of the Catawba Technical Specification.
See Inspection Report No. 50-413, 414/88-01 for details of a previous
examination of S/G tube inspection activities.
The following details the
inspector's review and observations and the problems identified during the
current inspection:
a.
As discussed in Inspection Report No. 88-01, the Eddy Current (ET)
inspection plan for the current outage specified testing 650 tubes in
S/G 8 and 628 tubes in S/G C.
As part of the licensee's program of
inspection for loose parts, the plan included 100% of the peripheral
tubes in both S/Gs.
During the current initial ET inspection, one
defective (degradation > 40% wall thickness) tube [ ROW (R) 41
Column (C) 20, 77% deg/G C.radalion) was found in S/G B and no defective
tubes were found in S
The defective tube in S/G B was a peripheral
tube and the defect was on the hot leg side near the tube sheet.
The
defective tube was plugged and 14 additional tubes in the vicinity
of the defective tube ET tested.
No additional defective tubes were
identified.
S/Gs A and 0 were inspected in August 1987 during an
earlier outage.
The inspection sample consisted of 370 tubes in S/G A
and 405 tubes in SG 0.
No defective tubes were identified in S/Gs A
and D.
As part of the licensee's sludge lancing and loose parts inspection
programs, the annulus areas of all four S/Gs were visually (VT)
inspected using fiber optics.
The following summarizes the results of the VT inspection:
S/G A - Pre Sludge Lance:
3 objects were found and removed
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(2" nail and 2 Pcs, of 1/16" wire-
10" and 14" Long)
Post Sludge Lance:
A carbon steel block
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(3-1/2"x 2"x 1-1/2") was found
on the tube sheet.
The block
was removed
S/G B - Pre Sludge Lance:
3 Jacking studs (2-1/4" dia. 3"
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long) were found and removed
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Post Sludge Lance:
One Carbon steel weld rod (1/8" x
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6"long) was found - not removed -
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S/G C - Pre Sludge Lance:
One Pc, of Wire (1/16" 2"long)
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and one small pc. of slag were
found and removed
Post Sludge Lance:
Nothing found
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S/G 0 - Pre Sludge Lance:
A sliver of flame cut metal (3/8"
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x 1/4"x 8"long) was found and
removed.
Tube R49/C64 showed
visual damage in the vicinity of
the sliver.
A small pc. of wire
was found and not removed -
assumed to be removed by sludge
lancing
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Post Sludge Lance:
Nothing Found
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All loose parts were on the tube sheet in the annulus area of the
S/Gs.
Two of the jacking studs in S/G B were adjacent to the
defective tube (R41/C20) noted above.
One stud was in a horizontal
position at the area of the defect in the tube.
The other was in a
vertical position near the tube.
The third stud was in the other hot
leg quadrant.
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As a result of finding loose parts in the S/Gs and the visible damage
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to S/G 0 Tube R49/C64, the August 1987, ET data for that tube was
reviewed.
The review revealed that the tube was defective (50% wall
degradation) and should have been plugged in August 1987.
The
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licensee then re-reviewed all of the ET data for the August 1987,
inspection of S/Gs A and O.
This review also identified a
in S/G A (Tube R15/C77, 68% wall degradation).pluggable
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condition
The
indication was located at the 5th support plate +35".
Therefore, the
plant operated from the summer 1987 outage until the current outage
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(December 1987) with two tubes, R49/C64 in in S/G 0 and R15/077 in
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S/G A) exceeding the plugging limit (> 40% wall degradation) of
Surveillance
Requirements
4.4.5.0
oT the plant Technical
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Specifications (TS).
The licensee also re-reviewed the preservice
(PSI) data for the two defective tubes.
For tube R49/064 in S/G D,
the PSI data did not show any indication.
For tube R15/C77 in S/G A,
the PSI deta showed an indication in the same area as the indication
identified in the August 1987 data but, the indication had only half
the amplitude with a Signal / Noise ratio of < 5/1.
The indication was
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identified as an "Undefined Signal" (UDS).
Based on the findings (2
pluggable tubes from the August 1987 inspection), the licensee was in
the process of performing additional ET inspections on S/Gs A and D.
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The above problem was reported to the NRC under 10 CFR 50.72
requirements.
Operating with two tubes that should have been plugged is in
violation of TS 3/4.4.5 and Surveillance Requirements 4.4.5.0 which
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require that each S/G be determined operable prior to increasing Tavg
above 200 F by aerforming the required augmented ET. inspection and
plugging defect've tubes.
This TS violation occurred because the ET
examiner failed to identify the rejectable ET signals when evaluating
the ET data in August 1987.
This failure to identify rejectable ET
signals indicates inadequate measures to control special processes
(ET testing) in accordance with 10 CFR 50, Appendix
8, Criterion IX,.
and is identified as Violation 414/88-09-01,
Failure to Establish
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Adequate Measures to Control ET Testing of S/G Tubes.
NRC has
previously identified to the licensee problems with failure to call
ET indications and the need to have a second independent review of
the ET data (See hformation Notice 84-49 and NRC Inspection Report
Nos. 50-369, 370/87-38 and 50-413, 414/87-38.
The licensee's
practice has been to have a single evaluation of the ET data.
A
double review would likely have prevented the missed calls identified
above. At the time of the 50-413, 414/87-38 inspection, the licensee
indicated that they were working toward improving their program to
include a second review.
During the current inspection, the licensee
committed to have two independent evaluations for all future ET
inspections.
Guidelines were being issued to cover the evaluation
process.
On February 9, 1987, the licensee reported by telephone that
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additional pluggable tubes (one in S/G 0 and three in S/G A) had been
identified by the additional
ET inspections that were in process at
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the close of the inspection.
b.
Ocring evaluation of the above problems, the inspector questioned the
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licensee concerning reportability.
The licensee had written two
problem investigation reports, one covering the loose parts and the
other covering the two tubes that should have been plugged during the
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August 1987 outage.
Their preliminary reportability determic.ation
indicated that the loose parts condition was not reportable and that
failure to plug the two tubes was a TS violation that would be
reported under the 30 day requirements of 10 CFR 50.73.
After
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discussion with the NRC, the decision was made to report the problem
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under 10 CFR 50.72.
The NRC expressed concern to the licensee relative to reporting
practices.
It appeared to the NRC that licensee personnel were
reluctant to report in a timely manner all known information
concerning the failure to identify, during a previous outage,
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significant stream generator tube degradation (68% wall thickness for
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1 tube).
It also appeared that complete information relative to loose
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parts found in the generator was given only as questions were asked
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rather than providing all information that was known.
It did not
appear that the intent was to hide information, but rather to wait
until all the facts were known and all questions resolved.
Although
the plant was in an outage when it was learned that two tubes should
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have been identified and plugged prior to startup after the summer
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1987 outage, and the licensee questioned requirements for prompt
reporting of this condition, the NRC is concerned that the
information was not, at least, presented informally as soon as the
information was available.
It was not necessary to resolve all
questions prior to informally indicating to the NRC that there
appeared to be a problem.
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The NRC also expressed to the licensee the need to be highly
sensitive toward loose parts on the secondary side of steam
generators since degradation of tubes (reactor coolant pressure
boundary) caused by loose parts cannot be predicted.
Although the
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detection of loose parts may not be promptly reported, when loose
parts are found on the secondary side of steam generators, along
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with significant tube wall degradation, the NRC needs to know as soon
as the information is known.
The matter is considered serious and is
of concern to the NRC because of the probability of a tube rupture
and the fact that tube degradation form loose parts cannot be
predicted.
As noted in NRC Information Notice 88-06, for some
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steam generators, tube rupture can occur during normal operations if
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tube wall thickness has been reduced by 85% to 90%.
One tubs in one
of the Catawba generators was found to be degraded by 77L
c.
As part of the evaluation of the above detailed problem with
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defective tubes, the inspector reviewed the following ET procedure
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and data:
B&W Procedure ISI-460, Revision 14, Technical Procedure for the
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Evaluation of Eddy Current Data of Nuclear Grade Steam Generator
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Tubing
August 1987 ET tapes for tube R15/C77 in S/G A and tube R49/C64
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in S/G D
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PSI ET tapes for Tube R15/C77 in S/G A and tube R49/C64 in
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S/G D
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d.
As noted above, VT inspection revealed a number of foreign (loose)
parts in the secondary side of the S/Gs.
As part of review of this
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problem, the inspector reviewed the following procedures relative to
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control of cleanliness in components:
QCD-1, Revision 12, Housekeeping During the Operations
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Phase o,' Nuclear Stations
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QCD-2, Revision 15, Cleanliness Control of QA Piping Systems at
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Nuclear Stations
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Maintenance Management Procedure 1.6, Revision 6, Housekeeping
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Requirements During Maintenance Activities on Open Systems and
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Components
CNS Directive 3.11.1 ( AS), Revision 16, Housekeeping and
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Cleanliness Levels in Safety and Non Safety-Related Areas
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In addition to review of the above procedures, the inspector reviewed
a number of work requests for current S/G work to determine if the
correct cleanliness zone was specified.
e.
Based on the problem identified with previous evaluation of ET data,
the inspector discussed, with the licensee, the need to review Unit 1
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data again.
The licensee stated that the Unit 1 data will be re-reviewed.
As some assume that the Unit 1 S/Gs do not have problems similar to
those identified in Unit 2, the licensee pointed out that the
secondary side of the S/G was VT inspected during the last outage.
In the areas inspected, no violations or deviation, except as noted in
paragraph a., were identified.
6.
ISI Data Review and Evaluation (73755) (Unit 2)
The inspector reviewed the ISI NDE records indicated below to determine
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whether the records were consistent with regulatory requirements and
licensee procedures.
See paragraph 5 above for the applicable code.
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NDE (magnetic particle) report for support 2-R-SM-1565 was reviewed.
The
report indicated that a crack was found in the support to pipe weld.
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inspector reviewed evaluation report CNS-88-001 and Problem Investigation
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Report (PIR) 2-088-0038.
The PIR indicated that the inspection sample was expanded to include ten
additional pipe supports.
No other indications were identified.
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Within the areas inspected, no violations or deviations were identified.
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7.
Independent Inspection Effort (73756)
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During the current inspection, a problem was identified with the operator
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(size 70 Rotork) on Unit 2 valve 2ND-2A (RHR 12" Gate Valve).
The
operator motor pulled loose and completely separated from the gear case.
The licensee had investigated the failure and determined the cause to be
as follows:
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In 1978, Rotork increased the size of bolts used for mounting the
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motor to the gear case for operators to be used in Nuclear
applications.
Therefore, if a post-1978 motor is mounted to a
pre-1978 gear case, a modification to the connection is required
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because of the oversize holes in the motor mounting flange.
Rotork
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provides instructions for the modification, which consist of a sleeve
for the oversized holes.
A flat washer is used over the sleeve to
provide bearing contact with the motor ' flange.
For the size 70/90
operator, the bolt size was changed fron; 5/16" to 1/2".
The flat
washer used is slightly larger than the hole in the flange and,
therefore, provides very little contact with the surface of the
mounting flange.
Due to the difficulty in unseating valve 2ND-2A, the torque switch
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was manually jumpered (the Rotork operator does not have a built in
bypass).
The intent was to bypass the
switch just'long enough to
unseat the valve.
For the Rotork operator, when the torque switch is
bypassed, the limit switch is also bypassed.
The valve moved off its
seat and traveled to fall open position with the torque and limit
switches jumpered out of the circuit to sto) the operation of the
motor.
When the valve reached full open position, the motor continued
to operate, applying force to the motor gear case connection.
Due to
the small contact surface between the flat washers and the motor
mounting flange (see above), the mounting bolts and washer were
pulled through the bolt holes in the flange, thus separating the -
motor from the gear case.
At the close of the inspection, the licensee was continuing to evaluate
the problem and identify corrective action.
For further details and
followup, see RII Inspection Report No. 50-413, 414/88-08.
Within the areas inspected, no violations or deviations were identified.
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