ML17228A620
| ML17228A620 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/07/1994 |
| From: | Casto C, Girard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17228A617 | List: |
| References | |
| 50-335-94-11, 50-389-94-11, GL-89-10, NUDOCS 9406270262 | |
| Download: ML17228A620 (24) | |
See also: IR 05000335/1994011
Text
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++*++
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W., SUITE 2900
ATLANTA,GEORGIA 303234199
Licensee:
Florida Power
and Light Company
9250 West Flagler Street
Miami, FL
33102
Docket Nos.:
50-335
and 50-389
Facility Name:
St.
Lucie
1 and
2
Inspection
Conducted:
ay
2 - 6,
1994
r1
ead
Ins ector:
Vc~
L
p
~
~
+ Girar
Other Inspector:
H. Hiller
Report Nos.:
50-335/94-11
and 50-389/94-11
License Nos.:
and NPF-16
Date Signe
Approved by:
Other
Personnel:
H.
olbrook,
Co
ultant
(EG&G Idaho,
Incorporated)
y~!
C. Casto,
Chief
Date Signed
Test
Programs
Section
Engineering
Branch
Division of Reactor Safety
SUMMARY
Scope:
This special,
announced
inspection
examined the implementation of the
licensee's
motor-operated
valve
(HOV) program to meet
commitments in response
"Safety-Related
Motor-Operated
Valve Testing
and
Surveillance."
The inspectors utilized the guidance
provided in Temporary
Instruction (TI) 2515/109 (Part 2), "Inspection Requirements for Generic Letter 89-10, Safety-Related
Motor-Operated
Valve Testing
and Surveillance."
As delineated
in Part
2 of TI 2515/109, this inspection
was the initial review
of the licensee's
implementation of its
GL 89-10 program.
The inspectors
conducted
interviews with licensee
personnel
and selectively
examined records,
procedures,
and hardware to evaluate
the licensee's
implementation of the
GL 89-10 program.
They also assessed
the licensee's
actions in response
to
a related
open item and other concerns identified in
previous
NRC inspections.
9406270262 9406i3
ADOCK 05000335
Q
Results:
The inspectors
concluded that the licensee
was in the process
of implementing
a generally satisfactory
HOV program.
However,
a violation and two
inspector followup items (IFIs) were identified, representing
weaknesses
in
the program implementation.
The violation and IFIs are
summarized
below and
described
in detail in the indicated report sections:
(Open)
Violation 50-335, 389/94-11-01,
Inadequate
Corrective Action for
HOVs Which Stalled Ouring Surveillances.
(Section 2.5.b)
In three instances
where
HOVs stalled during surveillance tests,
the
licensee failed to document possible
damage to and corrective action
for the valves
and actuators.
There were
no recorded calculations
of the thrust
and torque
caused
by stall to determine if limits
prescribed for the actuator
by the valve manufacturers
were
exceeded.
NRC inspectors'alculations
found the thrust produced
by
stall
was about
230 percent of the actuator thrust rating and
160
percent of its torque rating.
The thrust was
125 percent of valve
limit.
(Note:
The licensee did document
and address
possible
damage
and corrective actions for motors
and overload relays.)
(Open)
IFI 50-335,
389/94-11-02,
Inadequate
Recognition of HOV Test
Pressure
and Flow. (Section 2.3)
The licensee's
design-basis
differential pressure test for valve 1-
V-3660 did not accurately
determine differential pressure
at the
valve and did not assure
representative
design-basis
flow.
(Open)
IFI 50-335, 389/94-11-03,
Lack of Instructions or Guidance for
Trending
and Periodic Evaluation of HOV Failures.
(Section 2.5.a)
There
was
no procedure
or instruction specifying
who was responsible
to perform and evaluate
trend reports,
when the reports
were to
performed,
who would initiate recommendations
and corrective
actions,
how frequently the reports
were to be issued,
etc.
The licensee's
program implementation
was scheduled
to be completed
60 days
following start-up
from Cycle
13 refueling outage
(scheduled fall 1994) for
Unit
1 and Cycle
9 refueling outage
(scheduled fall 1995) for Unit 2.
Approximately 2/3 of the gate
and globe valves
had
been set
and tested
but
a
methodology
had not been established
for verifying the capabilities of
butterfly valves.
These
and other important aspects
of the program that
had
not been fully developed
and/or
implemented will require evaluation in a
subsequent
NRC inspection.
The inspectors specifically identified the
following issues for further inspection,
together with the violation and
followup items described
previously:
(1)
Completion of the development
and implementation of post maintenance
test
requirements.
(Section 2.4)
(2)
Establishment
and implementation of criteria for determining the
capabilities of butterfly valves.
(Section 2.6)
(3)
Revision of calculations for Direct Current
(DC) powered
NOVs (pullout
efficiency to be used in place of run efficiency).
(Section 2.2)
(4)
Justification for the adequacy of the method
used to extrapolate
HOV test
results to design-basis
conditions.
(Section 2.3)
(5)
Justification for the
HOV stem friction coefficient assumed
in
thrust/torque calculations.
(Section 2.2)
(6)
Completion of the development
and implementation of criteria for periodic
verification.
(Section 2.4)
(7)
Completion of the remaining setting
and testing of valves.
(Section 2.6)
(8)
Revision of program
and test procedures
to require that thrust margins
be
adequate
to account for appropriate uncertainties
(such
repeatability).
(Section 2.3)
(9)
Results of internal inspection of valve 1-V-3660.
(Section 2.3)
Previously identified IFI 50-335,
389/92-25-01
was closed
by the inspectors
based
on the review, described
in Section
2. 10.a,
which identified the above
violation.
Additionally, concerns identified in the previous
NRC inspection
(50-335, 389/91-18) of the licensee's
GL 89-10 program,
were either found
adequately
resolved
or will be addressed
in the
GL 89-10 closeout
inspection
for St. Lucie performed
by Region II.
The inspectors
observed that the quality of diagnostic data
used
by the
licensee
was particularly good
and considered this
a strength.
REPORT
DETAILS
Persons
Contacted
- L. Bearror, guality Assurance/guality
Control
- J. Connor, Technical Staff
- J. Cook, Electrical Haintenance
- W. Dean,
Supervisor,
Electrical Maintenance
- J. Hallem, Technical Staff Engineer
- G. Madden,
Nuclear Reactor Regulation Interface,
Licensing
- J. Hanso,
Engineer,
Mechanical
Engineering
- L, McLaughlin, Licensing Manager
- K. Hohindroo,
Production
Engineering
Group Manager
- D. Sager,
Vice President
- Plant St. Lucie
- C. White,
Commitment Tracking
and Routine Reports,
Licensing
- R. Winnard,
Juno Licensing
- J. Zudans,
Lead Engineer,
Mechanical
Engineering
NRC Personnel
2.0
- S. Elrod, Senior Resident
Inspector
- H. Hiller, Resident
Inspector
- Denotes personnel
that attended
the exit meeting.
and initialisms used throughout this report are listed in the
last paragraph.
GENERIC LETTER (GL) 89-10
"SAFETY-RELATED MOTOR-OPERATED VALVE [MOV]
TESTING AND SURVEILLANCE"
(2515/109)
On June
28,
1989, the
NRC issued
GL 89-10, which requested
licensees
and
construction permit holders to establish
a program to ensure that switch
settings for safety-related
HOVs were selected,
set,
and maintained
properly.
Subsequently,
six supplements
to the
GL have
been
issued.
NRC
inspections of licensee
actions
implementing
commitments to
and
its supplements
have
been
conducted
based
on guidance
provided in
Temporary Instruction (TI) 2515/109,
"Inspection Requirements
for Generic Letter 89-10, Safety-Related
Motor-Operated
Valve Testing
and
Surveillance."
TI 2515/109 is divided into Part
1,
"Program Review," and
Part 2, "Verification of Program Implementation."
The current inspection is the initial TI 2515/109 Part
2 program
implementation inspection.
The TI 2515/109 Part
1 program review for St.
Lucie was conducted
September
9 through 13,. 1991,
and .was documented
in
NRC Inspection
Report 50-335,
389/91-18,
dated
November
18,
1991.
The principal focus of this inspection
was to evaluate
in depth the
implementation of GL 89-10 for a sample of HOVs selected
from the
licensee's
program.
The
HOV sample
was chosen
from a list of valves that
had received differential pressure
(DP) testing.
The majority of the
valves selected
were gate valves with high design-basis
DP
(DBDP)
operating
requirements.
The
MOVs in the sample
were
as follows:
Valve
Number
Function
Size
Type
1-V-3480
1A Low Pressure
Safety Injection
Hot Leg Suction Valve
10 inch
Gate
1-HCV-3617
Auxiliary High Pressure
Safety
Injection Header
Flow Control
Valve to Loop IA2
2 inch
Globe
1-V-3660
2-V-3480
2-HCV-3615
High Pressure
Safety Injection
Pump Recirculation
To Refueling
Water Tank Isolation Valve
2A Low Pressure
Safety Injection
Hot Leg Suction Valve
Loop 2A2 Low Pressure
Safety
Injection Header Isolation Valve
3 inch
Gate
10 inch
Gate
6 inch
Globe
2-V-3654
High Pressure
Safety Injection
2B
Isolation Valve
6 inch
Gate
2-V-3658
2-V-3664
2-MV-08-13
Shutdown Cooling Heat Exchanger
2B Inlet Isolation Valve
2A Low Pressure
Safety Injection
Hot Leg Suction Valve
Pump Steam
Admission Valve
12 inch
Gate
10 inch
Gate
4 inch
Gate
2-MV-09-10
Discharge
Valve
4 inch
Globe
This inspection
also evaluated
actions which the licensee
had taken to
correct
a related violation and weaknesses
identified in previous
inspections,
as described
in Section
2.10 of this report.
Based
on this, the inspectors
concluded that the licensee
was
implementing
an acceptable
MOV program in response
to
However,
some weaknesses
were identified.
Additional
NRC inspection is planned to
complete the evaluation of some
areas
and to address
specific findings
identified below.
2. 1
Desi n-Basis
Reviews
For the above
sample of 10 MOVs, the inspectors
reviewed the licensee's
Generic Letter 89-10 Design-Basis Differential Pressure
(DBDP)
Calculations,
applicable operational
procedures,
system flow drawings,
pump curves,
and the design-basis
documents.
They verified that the
maximum flow and differential pressure
were determined for each
MOV.
Calculations for differential pressure,
voltage, flow, and temperature
2.2
were reviewed
and verified to be complete
and correct.
Determinations of
thrust
and torque were verified to use appropriate
inputs of the design
DP, voltage,
and temperature
corrected
motor torque capabilities.
The
inspectors verified that the licensee
completed
the
DBDP calculations for
all the safety-related
systems
and addressed
flow.
The licensee
had
been notified of the effects of elevated
temperature
on
motor torque through
a Potential
10 CFR Part 21 Notice dated
Hay 13,
1993,
and Technical
Update 93-03
(Harch
1993)
issued
by Limitorque
Corporation.
The licensee
issued Corrective Action Request
070593 dated
September
15,
1993, to initiate corrective action for the
HOV motors.
Engineering
Evaluation
JPN-SEHP-93-031
was initiated to address
the
effects of elevated
temperature
on the
HOVs and
recommend corrective
action.
The inspectors verified that the licensee
implemented
appropriate
corrective action
by revising the calculations for reduced
motor torque of the affected
HOVs.
The inspectors
concluded the licensee
had adequately
implemented the
design-basis
recommendations
of GL 89-10 for design-basis
reviews.
HOV Sizin
and Switch Settin
The inspectors
reviewed the licensee's
documentation for determination of
design-basis
thrust/torque
requirements for 5 of their selected
sample of
10 valves:
I-HCV-3617, 1-V-3660, 2-V-3654, 2-V-3664,
and 2-HV-08-13.
The licensee's
calculation of thrust requirements
was found to use
a
standard
industry thrust equation with a valve factor assumption of 0.50
for wedge gate valves
and
1. 10 for globe valves.
For determination of
actuator output thrust capability, the licensee
assumed
a stem friction
coefficient of 0.20.
Further,
a margin of approximately
10 percent
was
incorporated to address
HOV load sensitive
behavior (also
known as "rate
of loading" ).
Minimum thrust requirements for setting of actuator torque
switches
were adjusted to account for diagnostic
equipment
inaccuracy
and
torque switch repeatability.
The inspectors
noted that the licensee
had calculated
stem friction
coefficients using static test data for the purpose of justifying their
assumed
0.20 stem friction coefficient.
The inspectors
discussed
with
licensee
personnel
the importance of measuring
stem friction coefficient
under test conditions that are representative
of design-basis
conditions.
Licensee
personnel
stated this would be considered
in developing the
justification for their assumed
stem friction coefficient.
Region II
will review the licensee's justification during
a future inspection.
The licensee's
actuator manufacturer,
Limitorque, is understood
to have
recently
recommended
that pullout efficiency be used in place of run
efficiency for determination of actuator capability in the closing
direction for DC powered
HOVs.
Licensee
personnel
stated that
an
informal review of the impact of this information had
been
completed
and
that no concerns
were identified.
They indicated that use of pullout
efficiency for the closing direction for DC HOVs will be incorporated
by
2.3
revising the formal calculations.
Region II will review the result of
using pullout efficiencies during
a future inspection.
Desi n-Basis
Ca abilit
For their selected
sample of 10 valves,
the inspectors
examined
the
static test results,
dynamic test
packages,
and post-test
review
packages.
The dynamic test data
was evaluated
by the licensee
using
an
industry standard
equation,
the valves'rifice diameters,
and the
dynamic test conditions.
The evaluation indicated closing gate valve
factors
up to 1. 10 and load sensitive
behavior
as high as
6 percent.
Stem friction coefficients for the sampled
valves were
as high as 0.21
under static test conditions
(see Appendix).
Based
on this data, it did
not appear that the licensee's
0.50 valve factor assumption for gate
valves
was always bounding.
However, for those valves with high valve
factors,
the thrust margins applied to settings
had
been sufficient to
assure
satisfactory
performance.
The capabilities of sister valves
had
been demonstrated
by testing
under dynamic conditions.
To determine the operability of an
NOV, the licensee linearly
extrapolated
the thrust necessary
to overcome differential pressure
to
design-basis
conditions.
Licensee
personnel
stated that
a justification
for use of linear extrapolations
was under development.
Region II will
verify the adequacy of the justification in
a subsequent
inspection.
The licensee's
Calculation
PSL-BFJH-93-029,
Motor Operated
Valve Diagnostic Test Results Evaluation," issued
December
9,
1993,
documented
the method
used to extrapolate
dynamic test results
to design-basis
conditions,
where necessary.
This method stipulated that
the closing extrapolated
load is compared to the thrust measured
at
control switch trip (CST) to ensure that the torque switch is set
adequately for design-basis
conditions.
However, the inspectors
found
that the document did not specify any minimum level of margin that would
be necessary
to account for uncertainties
(e.g.,
repeatability or degradation
in valve/actuator
performance
from one test
to the next).
Licensee
personnel
stated
they would review the guidance
on this issue provided in Supplement
6 of GL 89-10,
and that their
program
and differential pressure test procedures
would be revised to
require that thrust margins
be adequate
to account for appropriate
uncertainties
(such
as torque switch repeatability).
Region II will
review the licensee's
resolution of this issue during
a future
inspection.
The licensee's
dynamic test evaluation for valve 1-V-3660 determined that
this
3 inch Velan flex-wedge gate valve
(Low Pressure/High
Pressure
Safety Injection
Pump Recirculation to Refueling Water Tank)
had
a valve
factor of 1. 10.
The inspectors'eview
of the diagnostic force trace
taken during the dynamic test indicated that flow isolation
was marked
just prior to the point where the valve appeared
to reach
hard seat
contact.
However, they noted that the force trace
had the characteristic
of a globe valve; there
was
no closing force plateau just following flow
isolation.
Such
a plateau is expected
because
of the uniformity of force
when the disc is sliding on the gate valve's seating
surface without any
change
in DP.
The seating portion of the static force trace
showed the
same
shape
as the dynamic test,
which caused
the inspectors
to question
the licensee's
choice of flow isolation
and determination of valve
factor.
After review of the static
and dynamic traces,
licensee
personnel
agreed that flow isolation was incorrectly marked,
leading to
an incorrect determination
oF valve factor.
There
was
no clear
indication of flow isolation
and the true valve factor was indeterminant.
The inspectors'eview
of the traces for a sister valve, located in
series with 1-V-3660 and tested
under the
same
dynamic conditions,
showed
normal gate valve flow isolation, characteristics
and
a valve factor of
0.51.
A possible explanation for the unusual
seating characteristic
is
an offset or deformation of the disc guides.
Licensee
personnel
indicated that,
because
of the unusual
trace,
1-V-3660 was scheduled for
inspection of the valve internals at the next outage of adequate
duration.
The licensee's
investigation of 1-V-3660 will be examined in a
subsequent
GL 89-10 inspection.
The inspectors
review of the dynamic test lineup and test results for 1-
V-3660 raised
two issues:
1-V-3660 was located in a recirculation line which had
a restricting
orifice, check valve,
and manual
valve between
the
pumps
and the
NOV.
The licensee
used
a pump discharge
pressure
gage to determine
the upstream
pressure for the dynamic test.
Because of the pressure
drop caused
by the components
located
between
the
pump and 1-V-3660,
the true pressure
at the valve was not measured
during testing.
Additionally, no assessment
for the difference
was noted in the test
results,
such that
a satisfactory
comparison to design-basis
conditions might be made.
Two pumps would be in operation during the identified design-basis
conditions for 1-V-3660.
However, the dynamic test
was conducted
with only one
pump running, providing approximately one-half the
volumetric flow rate that would be present
during the design-basis
event.
As the effects of flow on valve performance
are not readily
quantified, test conditions should simulate design-basis
flow as
near practical to facilitate assessment.
Licensee
personnel
indicated they would consider the above
when
evaluating the results of previous dynamic tests
and when developing
future dynamic test lineups.
The licensee's
failure to account for test
pressure
drops
and to assure
design-basis
flow was considered
a weakness.
It is identified as Inspector
Followup Item 50-335,
389/94-11-02,
Inadequate
Recognition of HOV Test Pressure
and flow.
Region II will
review the licensee's
related efforts during
a future inspection.
Based
on the data
examined,
the inspectors
concluded that the licensee's
testing
program for the
GL 89-10 program
HOVs provides the assurance
that
the tested
MOVs will perform their intended safety function.
2.4
Periodic Verification of HOV Ca abilit
2.5
Recommended
action "d" of Generic Letter (GL) 89-10 requested
the
preparation
or revision of procedures
to ensure that adequate
HOV switch
settings
are determined
and maintained throughout the life of the plant.
Section "j" of GL 89-10
recommends
surveillance to confirm the adequacy
of the settings.
The interval of the surveillance is to be based
on the
safety importance of the
HOV as well as its maintenance
and performance
history, but was
recommended
not to exceed five years or three refueling
outages.
Further,
recommended
that the capability of the
HOV be
verified if the
HOV was replaced,
modified, or overhauled to an extent
that the existing test results
are not representative
of the
HOV.
Licensee
personnel
informed the inspectors that development of a program
for periodic verification of the design-basis
capability of GL 89-10
HOVs
had not been
completed.
Electrical Haintenance
Hotor Operated
Valve
Program Hanual,
Section
F, indicated that periodic diagnostic testing
would be performed
on all
HOVs included in the scope of the
program
on
a
5 year schedule
and that the schedule
would be developed
following full implementation of initial baseline testing.
The
inspectors
were informed that static diagnostic testing would be used for
the verifications
and responded
that this was not yet an adequately
justified method.
Region II will assess
the adequacy of the licensee's
periodic verification of design-basis
capability during
a future
inspection.
The inspectors
found that,
in accordance
with procedure
HP 0950050,
"Post
Haintenance
Testing of Limitorque Hotor Operated
Valves," the testing
criteria for specific maintenance activities were to be determined
by the
HOV Coordinator.
The inspectors
questioned
whether this provided
adequate
control.
Licensee
personnel
stated
the procedure
would be
upgraded to include testing criteria for the various maintenance
activities.
Region II will verify the implementation
and adequacy of the
post maintenance
testing during
a future inspection.
HOV Failures
Corrective Actions
and Trendin
Recommended
action "h" of the generic letter requests
that licensees
analyze
and justify each
HOV failure and corrective action.
The
documentation
should include the results
and history of each as-found
deteriorated
condition, malfunction, test,
inspection,
analysis,
repair,
or alteration.
All documentation
should. be. retained
and reported in
accordance
with plant requirements.
It was also suggested
that the
material
be periodically examined
(every two years or after each
refueling outage after program implementation)
as part of the monitoring
and feedback effort to establish
trends of HOV operability.
a.
Trendin
and Periodic Examination of Failures
and
De radation
The inspectors
assessed
the following examples of the licensee's
trending
and periodic examination of HOV degradation
and failure data:
Motor Operated
Valve Trending
Program Report for valve 2-MV-09-10
(This report contained descriptive information, manufacturers
data,
dates of testing
and preventive maintenance,
and trend data
on
parameters
such
as stroke time,
megger results,
stem factor,
peak
thrust,
and thrust at control switch trip.
The report contained
diagnostic results
from 1994;
and stroke time, current,
and megger
data
from 1992
and 1994.)
Nuclear Plant Reliability Data System
Component Failure Analysis
Report
Component Failure Comparison
(Unit 2), dated July 2,
1993.
(This report compared
the St.
Lucie and industry failure rate
and
provided brief descriptions of the valve failures,
causes,
and
corrective actions for the period from October
1,
1991 through March
31,
1993.)
Maintenance
Procedure
No. 0940069,
Rev.
11, Preventive
Maintenance
of Non-Environmentally gualified Limitorque Motor Operated
Valve
Actuators.
(This was provided
by licensee
personnel
as
an example
to show that trendable
data
was being collected through preventive
maintenance
procedures.
The inspectors
found that it required
inspections
and recording of various data that could
be used to
identify degradation
and could
be trended.
Examples of the
inspections
included
stem thread condition,
run current,
and
functioning of position indication lights.
The inspectors verified
similar data
was recorded for environmentally qualified
actuators
through Procedure
0940072,
Rev. 8.)
The inspectors
review of the above indicated that trending
and
examination of MOV failures
and degradation
had
been initiated, except
that there were
no administrative controls governing the process.
There
was
no procedure
or instruction specifying
who was responsible
to perform
and evaluate
trend reports,
when the reports
were to performed,
who would
initiate recommendations
and corrective actions,
etc.
This was
considered
a weakness.
Licensee
personnel
indicated that this finding
would be evaluated
and appropriate
action would be taken.
The matter
was
identified as Inspector
Followup Item 50-335, 389/94-11-03,
Lack of
Instructions or Guidance for Trending
and Periodic Evaluation of MOV
Failures.
b.
Documentation
Anal sis
and Corrective Actions for MOV De radation
and
Failures
The inspectors
reviewed
and assessed
the adequacy of the licensee's
documentation,
analysis,
and corrective actions for MOV degradation
and
failures through
a review of selected
licensee
maintenance
Work Orders
(WOs)
and Nonconformance
Reports
(NCRs).
The
WOs were chosen
from the
printout of summary information in the licensee's
database
for 1993 - 94
maintenance.
The NCRs, covering significant failures,
were chosen
from a
listing of all
NCRs for a like period.
Two earlier
(1991
and
1992)
were added to the review because
of their apparent relation to failures
in the initial
WO and
NCR selection.
The
WOs reviewed
by the inspectors
included the following:
WO No.
Descri tion of Maintenance
91035976
01
92001072
01
92048525
01
93003402
01
93012842
01
On November
11,
1991, valve 2-HV-08-12 failed to open
(stalled) during testing.
The motor insulation exhibited
a burnt odor and the overload heater
was found to be
damaged
by overheating.
A sustained
motor overcurrent
condition was indicated.
The cause
was not established.
The motor, overload block,
and overload heater
were
replaced.
Static
and dynamic diagnostic thrust
measurements
did not reveal
any abnormality.
This was
an inspection of the internals of valve 2-HV-08-
12 during the refueling outage following the failure
documented
in the above
Work Order.
No visible cause of
valve binding was observed,
except that there were
possibly pipe wrench marks
on the upper
4 or 5 stem
threads
and
stem runout varied from 4 to 10 mils.
The
stem was replaced.
On September
15,
1992, valve 2-HV-08-13 showed dual
indication
and
was found to have stalled.
Motor, thermal
overload,
and starter
were replaced.
(Resulted
in NCR 2-
514 - described
in next table.)
Valve 2-V-3523 showed dual indication when closed.
This
was corrected
by adjusting limit switch rotor points to
provide correct indication.
Valve 2-HCV-3647 would not open.
No maintenance
was
required.
The reactor operator
had forgotten that the
switch had to be held in position to continue
movement in
the desired direction.
94008833
01
Valve 2-HV-09-11 would not operate
from the control
room
switch.
Checked limit switch development,
control switch,
and relay.
No problem was identified and,
subsequently,
the valve operated satisfactorily.
It was speculated
that
the valve did not operate
because
of dirty contacts.
93014982
01
93030826
01
Valve 1-V-3614 torqued out and would not close (preventing
reactor heat-up
and pressurization)
until forced off back
seat.
.Investigation
and repeated
testing did not identify
a problem.
Valve 1-HV-15-1 would not close.
The cause
was determined
to be dirty torque switch contact points.
The points were
cleaned
and the valve operated satisfactorily.
93017425
01
The position indicating lights for High Pressure
Safety
Injection System Valve 1-HCV-3616 were behaving
abnormally.
Investigation
found the hypoid gear
had
several
teeth missing.
Initiated
NCR 1-831
(see below).
j
The
NCRs reviewed
by the inspectors
included the following:
NCR No.
Condition and Corrective Action
1-820
(5/25/93)
1-831
(9/28/93)
This
NCR was
used to request
an engineering
review and
approval of a modification that drilled and pinned
a key
in the stem nut of valve I-NV-08-3.
Engineering
approval
was provided.
The limit switch cartridge pinion gear shaft
had failed on
valve 1-HCV-3616, potentially resulting in development of
stall in the closing direction.
An engineering
evaluation
determined that the Limitorque actuator one-time thrust
rating had
been
exceeded.
The actuator one-time torque
rating
and the valve thrust limit had not been
exceeded.
The engineering disposition referred to Limitorque
Technical
Update
92-01
as requiring
an inspection if the
rating was exceeded
and stated that the actuator
would be
rebuilt, exceeding
the Limitorque inspection requirements.
A failure analysis
was conducted
which identified the
probable
cause
as improper alignment of the hypoid and
pinion gears,
coupled with porosity found in the hypoid
gear.
Discussions
with the actuator manufacturer
indicated that this was
an isolated occurrence.
2-600
(4/15/94)
2-514
(9/16/92)
The closing thrust determined
at control switch trip
during diagnostic testing of valve 2-NV-08-13 exceeded
the
actuator allowable thrust limit.
Engineering
evaluated
and revised the thrust
and torque limits, based
on
Limitorque Technical
Update 92-01.
The previously
obtained torque
and thrust were acceptably within the
revised limits.
The high closing thrust obtained
in the
test
was attributed to an improvement in stem factor
(reduced friction), resulting in a higher thrust for the
same torque setting.
On September
16,
1992, valve 2-HV-08-13, the isolation
valve for the
supply to the
2C
pump. tur bine,,failed to open (stalled)
when actuated
to provide steam for a surveillance
run of
the
pump.
After opening
a sister
valve (HV-08-12), which
increased
the downstream
pressure
and decreased
the
differential pressure
across
2-NV-08-13, valve 2-NV-08-13
was again actuated
and successfully
opened.
Subsequent
investigation
found the motor and overload relay were
damaged
by overheating
and they were replaced.
The valve
opened
and closed satisfactorily after the replacement.
10
2-536
(7/20/93)
The licensee's
engineering
evaluation
concluded that the
root cause of the failure was indeterminant.
NCR 2-514
referred to subsequent
NCR 2-536, covering
a subsequent
failure of the
same valve, for additional evaluation
and
required actions.
On July 20,
1993, valve 2-HV-08-13 stalled while
attempting to open during
a surveillance test.
The stall
lasted
one to two minutes, after which the disc broke free
and traveled to full open.
No evaluation of the stall
thrust
and torque
was documented.
In a subsequent
diagnostically monitored full flow differential pressure
test,
a high unseating
load was recorded during opening of
the valve.
The actuator thrust rating was exceeded
by
approximately
30 percent.
The licensee
determined this
was acceptable
with the following actions
recommended:
a
limit of 50 complete cycles
on subsequent
valve operation,
valve surveillance
frequency increased
from every 60 days
to every 30 days,
disassembly
and inspection of the valve
and actuator at the next Unit 2 refueling outage.
Diagnostically monitored surveillance tests
in August
and
October found higher unseating thrusts
than previously
measured,
which were evaluated
and found acceptable
by the
licensee.
As
a consequence
of the October result,
the
licensee
changed
from torque to limit switch seating
control in an effort to reduce
wedging of the disc into
the valve seat.
During the next refueling outage
(February
1994) the valves were replaced with double disc
gate valves with larger actuators.
In assessing
the above
WOs and
NCRs, inspectors
found that the licensee's
documentation,
analysis,
and corrective actions for HOV degradation
and
failures
was satisfactory
except in addressing
the mechanical
overloads
experienced
by valves 2-HV-08-12 and -13.
These
are identical
HOVs and
perform redundant
safety functions.
The documented
analyses
of the stall
of valve 2-HV-08-12 on November
11,
1991,
and stalls of valve 2-HV-08-13
on September
16,
1992,
and July 20,
1993, did not determine
the torque
and thrust experienced
by the actuators
and valves (single wedge gate
type) for comparison to limits specified
by the manufacturers.
Calculations
by the
NRC inspectors
and,
subsequently,
by the licensee
indicated that the thrusts
and torques during the above stalls were
approximately
18,600 lbs
and
143 ft-lbs, respectively.
The calculated
thrust
was about
125 percent of .the valve maximum thrust limit described
in the licensee's
July 26,
1993, engineering
evaluation
JPN-PSL-93-038,
Rev. 0.
This deficiency was not identified or evaluated
in determining
the acceptability of the valves following any of the stall events.
Subsequently,
the licensee
has established
a valve thrust limit of 44,000
lbs, indicating the valve would not have
been
damaged
in the stall
events.
The calculated stall thrust
and torque were
230 and
160 percent
of the actuator
(Limitorque SHB-00) ratings, respectively.
As in the
case of valve thrust the actuator stall overthrust
and overtorque
were
not documented
or evaluated
in assessing
valve operability.
In February
1992,
Limitorque Technical
Update
92-01
was issued to notify
licensees
and others of recommendations
resulting from review of an
industry study to establish
increased
actuator ratings.
The Update
recommended
that the utility: contact Limitorque for an operability
assessment if actuator thrust exceeded
140 percent of the rating,
quantify any overthrust
by conservative
calculations
or measurements,
and
ensure
housing cover
and base fasteners
were torqued to specified
minimum
levels.
The Update also indicated that
a one-time overthrust of up to
250 percent of the actuator rating was acceptable.
Subsequently,
in
April 1992,
Limitorque issued
Naintenance
Update 92-1.
This Update
stated that if the
250 percent
one-time thrust rating was exceeded,
or if
the overload occurred
more than once,
an inspection of the actuator for
damage is recommended.
For opening overthrust, it recommended
inspection
of the drive sleeve
and lower drive sleeve
bearings.
The Haintenance
Update also stated that
a one-time torque overload of up to 200 percent
of the actuator rating was acceptable
but that, if this limit was
exceeded
or overtorque
occurred
more than once,
the gearing
and
particularly the worm should
be inspected for cracks.
Valve 2-NV-08-13 had experienced stall twice,
as stated
above,
and
may
have experienced
conditions
approaching stall at other times.
The
licensee
did not document the calculations
or inspections
recommended
by
the manufacturer to assure
the valves would perform their design safety
functions.
Instead,
the licensee relied
on diagnostic testing performed
following the stall failures.
Licensee
personnel
agreed that their documented
evaluation
was
insufficient but considered
the corrective actions they performed
adequate.
Their reasons
were
as follows:
(1)
At the time of the
1991 stall event they had
no written guidance
from Limitorque regarding evaluation of stall.
(2)
The one-time allowed actuator thrust
and torque specified
by
Limitorque were not exceeded.
(3)
Electrical Haintenance
performed
a visual inspection of the actuator
during motor replacement
following the
1992 event.
(4)
Diagnostic monitoring performed monthly following the
1993 stall did
not indicate
any damage to the actuator internals.
In addition,
visual examination of the actuator did not indicate
damage.
The use
of diagnostics
was considered
equivalent to vendor recommendations.
(5)
The valve manufacturer
indicated its thrust limit was 44,000 lbs,
which was not exceeded.
12
The inspectors'ssessments
of the reasons
given to justify the adequacy
of the licensee's
corrective actions
was
as follows:
(1)
An appropriate
engineering
evaluation
would have included
a
documented
and verified calculation of stall forces which could
be
compared with the actuator rating.
Considering that the stall
thrust calculated
during this
NRC inspection
was over twice the
actuator rating, it would have
been appropriate to seek guidance
from the manufacturer
or replace
the actuator.
(2)
The one-time actuator
allowed torque
and thrust is specified for
overloads
~u
to the stated limits. It is only for one (one-time)
overload up-to the allowable limits not multiple overloads.
The
licensee
experienced
two overloads
near the limits and at least
three additional
lower overloads
detected
during diagnostic testing.
Others,
up to stall overload levels,
may have occurred undetected.
(3)
Discussions
with licensee
personnel
indicated that this visual
examination
was not the inspection of components that Limitorque
recommends.
No documented
inspection results
were provided to the
inspectors
in support of an adequate
visual examination.
(4)
While the licensee's
diagnostics
did increase
assurance
that the
valve would perform its safety function, it would not be expected to
detect incipient failures
as assuredly
as the visual inspection
recommended
by Limitorque.
Based
on discussions
with licensee
personnel,
the licensee
performed
a visual inspection
but not the
inspection of components that Limitorque recommends.
No documented
inspection results
were provided to the inspectors
in support of an
adequate
visual examination.
(5)
The original thrust limit provided
by the valve manufacturer
was
9910 lbs.
As reported in the licensee's
1993 engineering
evaluation
(JPN-PSL-93-038)
performed following the second stall of 2-HV-08-13,
informal information from the vendor indicated the limit could
be
increased
to about
15,000 lbs.
This was below the stall thrust
calculated
during this inspection,
which is of 18,600 lbs.
The
licensee
was not aware that the limit could
be further increased
to
44,000 lbs until later.
Based
on the above,
the inspectors
consider the licensee's
actions in
response
to the valve stall failures unsatisfactory.
The licensee's
failure to document calculation
and evaluation of the" stall overload
conditions, to identify. the valve .and .actuator..overload,
and to perform
the evaluations
or inspections
recommended
by the actuator manufacturer
are considered
to represent
inadequate
corrective action.
This
inadequate
corrective action is identified as Violation 50-335,
389/94-
11-01,
Inadequate
Corrective Action for HOVs 'Which Stalled During
Surveillances.
13
2.6
Although the inspectors
determined
the licensee's
valve stall evaluations
were deficient, positive aspects
were also noted.
The application of
diagnostics
following the failures, particularly the periodic diagnostic
monitoring of valve performance instituted after the July 1993 stall,
provided increased
assurance
of valve operability.
The licensee
replaced
MOVs 2-HV-08-12 and
-13 at the first refueling outage following the
1993
stall with valves
and actuators
having improved capabilities.
However,
it appeared
to the inspectors that other actions
should
have
been taken
earlier
- either improved justifications for the continued operability or
valve replacement.
The adequacy of the licensee's
documentation,
analysis,
and corrective
actions for HOV degradation
and failures
was satisfactory with the
exception of actions of taken following stall failures.
Schedule
In GL 89-10,
the
NRC requested
that licensees
complete all design-basis
reviews,
analyses,
verifications, tests,
and inspections that were
initiated in order to satisfy the generic letter recommendations
by
June
28,
1994, or three refueling outages after December
28,
1989,
whichever is later.
In a letter dated
February
14,
1992, the licensee
proposed to change its schedular
commitment for completion to 60 days
following start-up
from Cycle
13 refueling outage
(scheduled fall 1994)
for Unit
1 and Cycle
9 refueling outage
(scheduled fall 1995) for Unit 2.
A subsequent
NRC acknowledgement letter,
dated
Harch 16,
1992, indicated
the change
was acceptable
but requested
that the more important valves
be
tested first, preferably in accordance
with the original schedule.
The inspectors
reviewed the documented
status of testing
and determined
that the licensee
had tested
approximately 2/3 of the globe
and gate
valves in the program for each unit.
In accordance
with the current
commitment,
one refueling outage
remains for each unit.
Licensee
personnel
stated that
some of the remaining valves would be tested during
operation.
Licensee
personnel
had not determined
what method that would be used to
verify the capabilities of butterfly valves but indicated that they
expect to meet the schedule
commitment.
Appropriate testing of butterfly
valves is an industry issue
and not unique to St. Lucie.
The inspectors
questioned
whether the licensee
had determined
the more
important valves to be tested
and completed testing of them first, as
requested
in the March 16,
1992,
NRC letter that acknowledged
the
licensee's
schedule
change.
They were provided copies of related letters
(dated January
29 and February
10,
1992) from the licensee's
engineering
group to the plant, which prioritized the valves for testing.
The
inspectors
reviewed the prioritization against
the licensee's list of
valves tested
and found that in some
cases
the higher priority valves
had
not been tested.
These
were discussed
with licensee
personnel.
Explanations
as to why the valves
had not tested
included: deletions
from
the program,
questions
as to whether valves were testable
at or near
2.7
design-basis
conditions, diagnostic
sensor
problems,
maintenance
problems,,
and on-going questions
regarding inclusion of certain valves in
the program.
Based
on the test data reviewed
by the inspectors
in this inspection
and
on their discussions
with licensee
personnel,
the inspectors
believe the
licensee
can meet the specified completion schedule.
The licensee's
completion of the setting
and verification of the capabilities of all
valves in the
GL 89-10 program (including butterfly valves) will be
confirmed in a subsequent
inspection.
Pressure
Lockin
and Thermal
Bindin
The Office for Analysis
and Evaluation of Operational
Data has completed
a study of pressure
locking and thermal binding of gate valves.
It
concluded that licensee's
have not taken sufficient action to provide
assurance
that pressure
locking and thermal
binding will not prevent
a
gate valve from performing its safety function.
The
NRC regulations
require that licensees
design safety-related
systems to provide assurance
that those
systems
can perform their safety functions.
In GL 89-10, the
staff requested
licensees
to review the design-basis
of their safety-
related
HOVs.
The inspectors
reviewed the licensee's
engineering report that addressed
pressure
locking and thermal binding.
Engineering Evaluation
JPN-PSL-
SEMP-93-036,
"St. Lucie Units
1
& 2 Engineering Evaluation of Pressure
Locking and Thermal
Binding of Motor Operated
Gate Valves," Rev.
0,
was
performed
by the licensee to identify safety-related
motor operated
valves that might be susceptible
to pressure
locking and/or thermal
binding.
An initial screening of the 80
HOVs in Unit
1 and the
103
HOVs
in Unit 2 was conducted to determine if the
HOVs met screening criteria
for susceptibility to pressure
locking or thermal binding.
The screening
criteria for pressure
locking susceptibility was:
(1) flexible-wedge or
double disc wedge gate design,
(2) used for incompressible fluids,
and
(3) lacking
a design feature for prevention.
The screening criteria for
susceptibility to thermal
binding was (1) flexible-wedge,
solid-wedge,
or
split-wedge gate design;
and (2)
HOV closed
under high temperature
conditions.
In Unit 1,
14 HOVs met the initial screening criteria for
pressure
locking and
19 met the initial screening criteria for thermal
binding.
In Unit 2,
12
MOVs met pressure
locking and
15 met thermal
binding initial screening criteria.
A further evaluation determined that
nine
HOVs (four in Unit
1 and five in Unit 2) were susceptible
to
pressure
locking.
Two MOVs in Unit
1 were determined to be susceptible
to thermal
binding.
The .transmittal .letter for the .above evaluation,
JPN-PSLP-94-0132,
dated
February
28,
1994, identified the
HOVs found to
be susceptible
to pressure
locking and thermal
binding as follows:
il
Pressure
Locking
Valves 1&2-V-3480, 1&2-V-3481, 1&2-V-3651, 1&2-V-3652, and 2-V-3545
15
Valves 1-V-1403 and 1-V-1405
At this point the inspectors
and licensee
did not have operability
concerns with these
valves.
The licensee
has adequately
considered
valve
operability.
However, the letter indicated that
a detailed valve
specific engineering
analysis
would be performed for the
above valves to
determine
any required action.
The
NRC plans to issue additional
recommendations
to licensees
regarding
pressure
locking and thermal
binding in the future.
Subsequently,
the
NRC will assess
licensee
actions in this area.
2.8
Hotor Brakes
St. Lucie did not have motor brakes
on their HOVs.
2.9
ualit
Assurance
Pro ram
Im lementation
The inspectors
reviewed the licensee's
implementation of the quality
assurance
(QA) function for the
Program
HOVs.
They found that
audits
and reviews
had
been performed
by the Nuclear Engineering
Department,
Independent
Safety Evaluation
Group (ISEG), Site
QA, and
Corporate
QA.
The inspectors
reviewed the following examples:
Nuclear Engineering
Department
self-assessment
letter JPN-ST-92-150,
"Design Review/Functional
Review
HOV - Testing," dated
June
12,
1992.
ISEG Report
ISEG-PSL-V-048,
"Evaluate Hotor Operated
Valve
Differential Pressure
Testing at St. Lucie," dated
June
22,
1993.
Corporate
QA audit,
QAS-JPN-93-3,
"Nuclear Engineering-PSL
Design
Control," dated October 29,
1993.
Site
QA contractors
audits
QSL-OPS-92-872 for the
HOVATS (HOV)
Program
and QSL-PS-92-872 for Babcock
8 Wilcox HOV Testing.
Based
on their review of the above,
the inspectors
concluded the licensee
has
implemented
an effective
QA program to address
HOVs.
'2. 10 Followu
of Previous
Ins ection Findin s
The inspectors
reviewed the licensee's
actions in response
to an
inspector followup item and other concerns identified in previous
NRC
inspections.
The results of the inspectors'eview
are described
below:
16
a.
Ins ector Followu
Item
(Closed)
IFI 50-335,
389/92-25-01,
Review of Operability of Unit 2
HOV
HV-08-13 During the Period of July 20 to October
19,
1993.
This item questioned
the operability of valve 2-HV-08-13 during the
period of July 20 to October
19,
1993.
The failures experienced
by this
valve
and the licensee's
corrective actions
were examined
in detail
by
the inspectors,
as described
in Section 2.5.b of this report.
During the
period in question
the licensee
performed
a number of surveillance tests
on the subject valve and in each
instance
the valve opened
when actuated
to perform its intended safety function.
Based
on the testing results
and evaluations
discussed
in this report, the inspectors
consider the
valve to have
been operable
during that period
and this item is closed.
It should
be noted that the related review described
in Section 2.5.b,
identified that the licensee's
corrective action for stall failures of
this valve was deficient, in that the July 20,
and previous related
failures were inadequately
analyzed.
Hore complete analysis
might have
led to
a licensee
conclusion that the HOV's capabilities
were
significantly degraded
and required
immediate replacement
or further
justification for continued operation.
Note that valve 2-HV-08-13 and
its redundant sister valve were replaced
by the licensee
during
a
February
1994 outage.
b.
Concerns Identified b
Ins ection 50-335
389 91-18 for Which
a
Written Res
onse
was
Re uested
(1)
Schedule
The concern
was that the licensee
might nut meet its generic letter
schedule
commitment due to delays
caused
by its recent decision to alter
its diagnostic test method.
In a response letter to the
NRC dated
February
14,
1992, the licensee
proposed its revised
schedule.
As
discussed
in Section 2.6 above,
the inspectors
examined the licensee's
related actions
and believes that the current commitment
can
be met.
This resolves
the concern.
(2)
Valves to be Design-Basis
Tested
The concern
was that design-basis
testing
was being omitted
on HOVs that
were practical to test.
Licensee
personnel
stated that credit might be
taken for testing of 56
NRC Bulletin 85-03 valves
even though only 23 had
been tested.
Also, the. licensee's
status report, indicated testing
was
being omitted for butterfly valves that were practical to test.
In the response letter referenced
above,
the
NRC was informed that the
licensee
would test all valves practical.
The licensee's
testing of all
valves practical will be assessed
when Region II inspects
the licensee's
completion of GL 89-10 implementation.
17
c.
Concerns
Identified b
Ins ection 50-335
389 91-18 for Which No
Written Res
onse
was
Re uested
(1)
Setpoint
Window
The concern
was that the licensee
had
no procedure
or programmatic
guidance for transforming design calculation results into valve setpoint
windows.
In the current inspection the
NRC inspectors
determined that
adequate
setpoint
windows had
been established
for the valves
sampled.
This resolves
the concern.
(2)
Use of 0.5 Valve Factor to Account for Uncertainties
Such
as
Rate of Loading
The concern
was that the licensee
had not adequately
accounted for
uncertainties
such
as load sensitive
behavior in its thrust setting
determinations.
The inspectors'eview,
described
in Section 2.2 above,
found that load sensitive
behavior
and other factors originally of
concern
are being addressed.
This resolves
the concern.
(3)
Justifiable Deviations from Commitment to Test All Valves
Practicable
The concern
was that the licensee
was evaluating deviations
from the
generic letter recommendation
to design-basis
DP test all valves
practicable for valves with high margins of capabilities to design-basis
requirements.
The inspectors
reconsidered
this issue
and do not find the
deviations of concern, if adequately justified.
Such justifications will
be subject to evaluation in a subsequent
inspection.
The original
concern is resolved.
(4)
Use of Static Diagnostic Testing to Demonstrate
Continued
Capabilities
The concern
was that the licensee
planned to use static diagnostic
testing for periodic verification of HOV capabilities.
The ability of
static diagnostic testing to demonstrate
continued capabilities
has not
been justified.
In the current inspection the
NRC inspectors
were
informed that the licensee
had not completed the determination of the
method
and criteria to be used for periodic verification.
This issue
will be inspected
during program closeout.
(5)
Stem Friction Coefficient and
Stem Lubrication Frequency
This concern
involved the licensee's
use of a low stem friction
coefficient and
a stem lubrication frequency greater
than
recommended
by
the manufacturer.
A valve stem friction coefficient of 0.15 was utilized
in calculating torque switch settings for St. Lucie
GL 89-10 valves
located outside containment.
The valve actuator manufacturer
indicates
this stem friction coefficient is to be applied where good stem
lubrication is assured
and, in practice,
the manufacturer
normally uses
a
more conservative
0.20 stem friction coefficient for its own
18
calculations.
Also, the actuator manufacturer
recommended
an
18 month
preventive
maintenance
frequency for valve stem lubrication, whereas
the
licensee
permitted
a 36 month frequency
on its non-equipment
environmental qualification (Eg) valves.
In the current inspection the
NRC inspectors verified that the licensee
was
now using 0.20 stem friction coefficient.
The licensee
stated that
the valve stem lubrication frequency of 36 months applied only to non
Eg
HOVs located inside the buildings.
The licensee further stated
that the 36 month valve stem lubrication frequency will be adjusted
as
needed to ensure
the stems
are properly lubricated.
The inspectors
concluded the licensee
has adequately
addressed
the valve stem friction
coefficient of 0.20
and stem lubrication.
This concern is resolved.
The
licensee's
verification that its 0.20 stem friction coefficient
assumption
and the 36 month lubrication frequency is adequate will be
subject to
NRC verification in a subsequent
inspection.
(6)
Torque Seated Butterfly Valves
The concern
was that
some butterfly valves were being seated
using torque
switch control, whereas
the actuator manufacturer
recommended limit
switch seating.
In the current inspection the
NRC inspectors verified
that the licensee
had implemented
a change to limit switch seating for
all butterfly valves.
The change
was identified
PCH 284-292
and
implementation
was verified by the inspectors
review of Work Order
examples
93027861,
93028660,
93028658,
93028659,
and 93028655.
This
concern is resolved.
(7)
Specification of Extrapolation
Method and
Use of Prototype
Testing
The licensee's
program document indicated that test results
obtained at
less than design-basis
DP would be extrapolated
to design-basis
DP and
that prototype testing would be used in some cases.
The concern
was that
no criteria were provided for use of either.
In the current inspection
the
NRC inspectors
found that the licensee
used
simple linear
extrapolation
and that there
was
no apparent
use of prototype testing.
Licensee
personnel
indicated that justification for the adequacy of
linear extrapolation
was under development
(see Section 2.3).
Any
licensee
use of prototype test results will be subject to
NRC evaluation
in establishing
the licensee's
completion of GL 89-10 implementation.
(8)
Guidance for Documenting
and Trending
MOV Failures
and
Degradation
The concern
was that the licensee
had not provided adequate
guidance for
performing the trending of HOV failures
and degradation
recommended
by
As discussed
in Section 2.5.a
above,
the current inspection
determined
there is still concern regarding the adequacy of the guidance
provided, particularly with regard to administrative controls.
19
2. 11 Walkdown
The inspectors
conducted
a walkdown of HOVs to observe
the installed yoke
thrust sensors
and the condition of the valve stems.
They observed that
the
HOVs located inside buildings were in good condition.
The valve stem
lubrication was satisfactory
and the sensors
were installed correctly.
HOVs located ou'tside,
where they were exposed to rain and salt air, were
inspected after removing the valve stem covers.
On
a previous
inspection,
an
NRC inspector
had observed that rain water
had leaked into
similarly located
HOVs and corrosion
had resulted.
The licensee
had
special
"hats"
made to cover the valves
and initially installed
them
on
two HOVs to determine if they provided protection from the environment.
The inspectors
found that the two HOVs with "hats" were in good condition
with adequate
stem lubrication and
no corrosion.
The other
HOVs located
outside
were observed to have
adequate
stem lubrication but some minor
corrosion.
The sensors
were satisfactorily attached
to the yokes of all
the
HOVs inspected.
The licensee
stated
"hats" would be installed for
all outside
MOVs by the
end of 1994.
The inspectors
considered
this to be appropriate corrective action.
The inspectors
concluded that the
HOVs located inside the buildings were
well maintained.
However, the
HOVs located outside
were subject to
corrosion
from the rain water and the salt air environment
and
some form
of protection
appeared
appropriate.
EXIT INTERVIEW
The inspection
scope
and findings were summarized
on Hay 6,
1994, with
those
persons
indicated in Section
1.
The inspectors
described
the areas
inspected
and discussed
in detail the inspection results.
Three
weaknesses
were described.
The inspectors
stated that one of the
weaknesses
would be discussed
with NRC management
as
a possible violation
and that the other two would be identified as followup items.
Licensee
personnel
indicated the reasons
they did not consider the
one item
a
violation.
Their reasons
are described
in Section 2.5.b,
above.
Proprietary information is not contained in this report.
The violation
and followup items identified by the inspectors
are listed in the
summary
at the beginning of this report.
ACRONYHS AND INITIALISHS
CFR
DBDP
DP
Eg
GL
IFI
ISEG
HOV
NRC
Code of Federal
Regulations
Control Switch Trip
Design Basis Differential Pressure
Differential Pressure
Equipment gualification
Generic Letter
Inspector
Followup Item
Independent
Safety Evaluation
Group
Motor Operated
Valve
Nonconformance
Report
Nuclear Regulatory
Commission
20
TI
VOTES
NRC Office of Nuclear Reactor Regulation
Quality Assurance
Temporary Instruction
Valve Operation Test
and Evaluation
System
APPENDIX - ST. LUCIE GATE AND GLOBE VALVEDATA
Diagnostics: VOTES/VTC/LVDT
TESI'ONDIONS
(pntO
DEQGN
BAQS
DYNAMIC
VALVE
FACTOR"
STEM
FRICIION
COEmCIENTi
LOAD"
SENQTIVE
BEHAVIOR
1-V3660
3
Velan
900'lex
Wedge
Gate Valve
N/A
1200
79%
0.21
1.10
NIC'/C
-5%
1-V3480
10" Velan
1500'lex
Wedge Gate
Valve
230
84%
1.0
0.14
N/C
N/A
1-HCV-
3617
2" Vclan
1500It Globe
Valve
1280
1000
52%
76%
0.34
0.11
N/C
2-V3480
10'estinghouse
15001 Gate
Valve
248
90%
0.59
N/A
N/C
N/C
-2%
2-HCV-
3615
6'elan
15001t Globe
Valve
417
142
87%
29%
0.95
N/C
0.16
N/C
-20%
2-V3654
6r
9008'ato
Valve
740
740
135%
135%
0.72
0.80
0.16
N/C
2-V3658
12
300/r Gate
Valve
4I5
93%
0.44
0.21
NIC
-2%
2-V3664
2-MV-
09-10
10'estinghouse
300'ato
Valve
4'KM 6000
Globe
Valve
1380
39
80%
14%
100%
3%
0.94
N/C
N/C
N/C
0.16
0.17
N/C
NIC
-2%
2-MV-
08-13
4'nchor
Darling 600/
Parallel Disc
Gate Valve
10
89%
1%
0.54
0.31
0.19
NIC
'ha dynamic valve factors listed were calculated by tha licensee using an orifice diameter.
Stem Lubricant: FelPro N5000.
'
negative number indicates that tha thrust observed at CST during tha dynamic test was greater than the thrust obscrvcd at CST during tho static
test.
'/C ~ Not Calculated.