ML17223A488
| ML17223A488 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 01/17/1990 |
| From: | Blake J, Glasman M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17223A486 | List: |
| References | |
| 50-335-89-29, 50-389-89-29, NUDOCS 9001310266 | |
| Download: ML17223A488 (8) | |
See also: IR 05000335/1989029
Text
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323
Report Nos.
50-335/-89-29
and 50-389/89-29
Licensee:
Power
and Light
Docket Nos.:
50-335
and 50-389
Facility Name:
St.
Lucie
1 and
2
License Nos.:
and
Inspection
Co
uc
Inspect r:
J~I.
M
G
Approved by
N
ber
27 through
December
1,
1989
<g..
an
Date Signed
/ /7
Fd
J..
a e, Chief
M
er/als
and Processes
Section
git eering
Branch
Division of Reactor Safety
Date Signed
SUMMARY
Scope:
This routine
unannounced
inspection
was
conducted
in response
to previously
identified issues
pertaining to Limitorque actuator maintenance.
The inspector
examined
the
licensee's
program for contractor
oversight,
vendor
technical
manuals,
and the licensee's
response
to the simultaneous
failure of two Unit 2
motor operated auxiliary feedwater discharge
valves to operate
as designed,
on
September
23,
1989.
Results:
This inspection
documents
an ineffective contractor
surveillance
program for
mechanical
maintenance.
Several
examples
of 'lack of technical
oversight
were
identified relating
to Limitorque maintenance.
It was also
found that the
licensee
did
not
have
adequate
procedures
for mechanical
maintenance
of
Limitorque actuators,
and the vendor technical
manuals for Limitorque actuators
were outdated,
and did not contain
adequate
instructions for certain critical
aspects
of actuator
maintenance
which, if not followed, adversely affect its
operation.
Note that
the
licensee
is in the
process
of implementing
new
mechanical
maintenance
procedures
for Limitorque actuators.
Responsibility for
all Limitorque maintenance
was shifted to one department.
This was considered
to
be
an excellent
move in the direction of improving Limitorque maintenance.
The licensee's
root
cause
analysis
of the
simultaneous
failure of the
two
Unit
2 motor operated
valves
was considered
thorough
and
accurate.
One violation was identified in the
areas
of inadequate
procedures
and,failure to follow procedures
(paragraph
2).
900 k 3 $ 02/~(>
I-"IDOI"K (1500033'.=
FBI".
REPORT DETAILS
Persons
Contacted
Licensee
Employees
'R. Ball, Mechanical
Maintenance
Planning
- J. Barrow, Supervisor,
Fire Protection
"J. Barrow, Operations
Superintendent
"H. Buchanan,
Supervisor,
Health Physics
"R. Church,
Independent
Safety Evaluation
Group
- J. Cook, Electrical Maintenance
~D. Culpepper,
Supervisor,
Site Engineering
- B. Dean, Electrical Maintenance
~R. Decker,
Independent
Safety Evaluation
Group
- D. English, Mechanical
Maintenance
Planning
"A. Flowers,
Mechanical
Maintenance
"J. Harper, Quality Assurance
Superintendent
- K. Keene,
Mechanical
Maintenance
"T. Kreinberg, Contracts
Supervisor
- L. McLaughlin,
Lead Engineer,
Plant Licensing
- W. Mead, Plant Coordinator,
Reactor Engineering
"D. Newberry,
Mechanical
Maintenance
- B. Parks,
Quality Assurance
Supervisor
- D. Sager,
Site Vice President
"R. Sipos,
Plant St.
Lucie Services
Manager
"C. Swiatek, Technical Staff, Licensing
"D. West, Technical Staff Supervisor
"G. Wood, Supervisor, Reliability and Support
Other
licensee
employees
contacted
during
this
inspection
included
craftsmen,
engineers,
operators,
technicians,
and
administrative
personnel.
NRC Resident'nspectors
"S. Elrod, Senior Resident
Inspector
"N. Scott,
Resident
Inspector
"Attended Exit Interview
Action on Previous
Inspection
Findings (92701)
(Closed)
Unresolved
Item
UNR 50-389/89-24-03,
Valve
Failures
The
Inspector
examined
vendor
manuals,
completed
plant
work orders
(PWO's),
procedures
associated
with the
preventative
and
corrective
maintenance
of Limitorque actuators,
and held discussions
with cognizant
licensee
personnel
regarding
Limitorque maintenance.
Background
On September
23,
1989, following a Unit 2 manual reactor trip, motor
operated
discharge
valves for both motor driven auxiliary feedwater
pumps
drove, open,
as
designed,
following receipt
of
an auxiliary
actuation
system
(AFAS) signal.
These
valves,
MV-09-09,
and
MV-09-10 are
equipped with Limitorque actuators.
Approximately
45 minutes
after
the
reactor .trip, operators
tried to reposition
MV-09-09,
and the valve would not respond;
operators
also attempted
to reposition
MV-09-10, and this valve could only be
stroked
in .the
closed direction.
Operators
were
then
sent
to the valves
and found
that
MV-09-09 could
not
be
positioned
remotely
or manually;
the
operators
were,
however,
able to manually position MV-09-10.
Upon disassembly
of MV-09-09, it was
found that the
upper
stem
and
actuator
stem
nut
were
bound
and
galled
together.
The
inspector
exami ned the failed stem
and
stem nut (which were cut in half by the
licensee for inspection)
and
found that the upper portion of the
stem
was
bound to the
bottom portion of the
stem nut; the'upper
lands of
the formerly square
cut threads
of the
stem
nut were
now worn to
about
a
45 degree
angle
on the top portion of the threads
in the
galled
length
of
the
stem.
The
upper
stem
was
made
of
aluminum-bronze,
and the actu'ator
stem nut was
made of bronze.
These
materials
are
similar
in
hardness,
and
in
a
sliding
thread
application, it is
not
recommended
'that similar materials
be
used
because
the
likelihood of binding
and
galling is significantly
increased.
This
was
confirmed
by the valve manufacturer,
and the
valve actuator
manufacturer.
The licensee
determined
the
cause
of
failure to
be
inadequate
lubrication in the failed portion of the
stem and
stem nut.
The licensee
has
repaired
the actuator for valve MY-09-09, however,.
the
same
bronze
materials
were
used
for
stem
and
stem
nut
replacements;
stainless
steel
stems
for this valve,
and three
other
valves with aluminum-bronze
stems
in the Unit 2 AFM system
have
been
ordered,
and will be, installed
under the Plant St.
Lucie (PSL) Plant
Change Modification program.
Upon
disassembly
of the
MV-09-10 actuator,
the licensee
found the
limit switch pinion and drive sleeve
bevel
gear teeth
had worn to the
extent
that
they
were
no
longer
in
mesh with each
other.
The
actuator
would not respond
to
an
open
demand
from the control
room
because
the limit switch
was
disengaged
from the
operator
which
would not allow the actuator
motor to rotate in the "open" direction.
The inspector
examined
the
worn limit switch pinion gear
and
noted
that the
gear teeth tips were burnished
and worn.
There
was also
some spalling evident
on
some of the the gear teeth flanks,
and the
inspector
noted
approximately
0.020" to 0.040" of wear
on the gear
teeth tips.
The licensee
determined
the root cause
of the failure
to be the combination of an improperly sized
upper
handwheel
and
mproper limit switch cartridge
clearance.
According to the
licensee,
the handwheel. gasket
was 0. 116" thick, and should
have
been
0.015" thick.
Limit switch cartridge
clearance
is adjusted
with
shims of varying
thickness'rocedure
and Vendor Manual
Review
The inspector
performed
a review of 'vendor manuals
and preventative
maintenance
procedures
for
actuators;
the
inspector
determined
that
there
were
no
procedures
in
use
by
mechanical
maintenance
for corrective
maintenance
on
Limitorque actuators.
Mechanical
repair work on Limitorque actuators
required
mechanical
maintenance
planners
and journeymen to work from controlled copies of
vendor technical
manuals.
The inspector
found,
however,. that
some of
these
vendor
manuals
for Limitorque actuators
were outdated.
The
manual for Unit 2 Limitorque maintenance
in use at the time of the
inspection,
SMBI-79,
was
issued
in 1979,
and the most recent
vendor
technical
manual,
SMBI-82C was
issued
in 1982.
It should
be
noted'hat
the
newest
vendor
technical
manual
contained
explicit
instructions for determining
the proper thickness .of the
handwheel
the old version of the
vendor
manual
in use
by mechanical
maintenance
at
the
time of the
inspection
did not contain
these
instructions.
The licensee,
however,
did have
an
18 month mechanical
preventative
maintenance
(PM) procedure
for Limitorque actuator s.
This
procedure,
2-M-00180,
Revision
5,
PM File .10500
covers
inspection of the actuator
gearcase
grease,
greasing
the upper thrust
bearing,
and lubrication of the valve stem,
among other things.
This
procedure,
however,
was
inadequate
in that
the
instructions
(in
paragraph
4.8 of the procedure)
do not ensure
the entire valve stem
receives
an
even coating of grease.
The pertinent instruction
says
"Clean
the
valve
stem with kerosene
and
rags;
apply
a
coat of
anti-seize lubricant."
This does not stress
the importance of making
certain
lubricant is distributed
evenly
over
the entire valve stem,
including that portion of the valve stem hidden
by the
stem nut.
The
licensee
indicated
to the inspector that the
18 month
PM procedure
was being revised to incorporate
more explicit instructions
on
stem
lubrication,
among
other
improvements.
In addition, the licensee is
in the process
of preparing
new mechanical
maintenance
procedures
for
Limitorque actuators.
Further, all Limitorque maintenance
electrical
and
mechanical)
will
be
the
responsibility
of
the
electrical
maintenance
department.
This
was
done
to streamline
and
improve
maintenance
of Limitorque actuators.
The licensee
indicated that all
electrical
maintenance
planners
and journeymen
involved in Limitorque
maintenance
have
already
received
training
on
Limitorque actuator
maintenance.
The lack of adequate
PM procedures
to ensure
valve
stems
are properly
lubricated
on motor operated
valve actuators
was identified to the
licensee
as violation 50-335,389/89-29-01,
Inadequate
Procedure.
Review of Completed
Limitorque Maintenance
Procedures
The
inspector
reviewed
the
maintenance
history of Unit 2 valves
MV-09-09,
and
MV-09-10,
the. auxiliary
discharge
valves
which did not function as designed,
following the September
23,
1989,
reactor trip (paragraph
2.a) to determine if root cause
analysis
was
performed
for
previous
failures;
for
abnormal
conditions;
if
contractor
oversight
was evident,
and if materials
and supplies
used
in actuator
maintenance
were properly
documented
in work packages.
The
inspector
also
performed
a similar review of other
selected
safety-related
Limitorque work packages.
The results of these
reviews
are listed below by valve number, plant work order
(PWO) number,
and
date.
Date
Unit
12/27/85
2
Valve No.
MV-09-9
PWO No.
Remarks
2570
Valve
did
not
operate
electrically.
Replaced
stem.
No
root
cause
documented..
FPL Work
3/29/89
2
MV-09-9
0212
Valve
made
very
loud
squealing
noise
when
stroked
open.
Repacked
upper
thrust
bearing.
Did
not
document
condition
of
stem
or
stem nut,
or
valve
internals.
Contractor
Work
9/23/89
2
MV-09-9
0476
Valve
stem
and actuator
stem nut bound together.
Root cause primarily due
to inadequate
grease
on
stem/stem
nut.
9/23/89
2
MV"09-10
5725
Limit switch pinion gear
not meshed properly with
drive sleeve
gear.
Root
cause
was
handwheel
cover gasket
too thick.
FPL Work.
7/4/89
1
MV-09-13
0478
Valve stem threads
worn;
no root cause
documented.
FPL Work.
3/13/89
2
MV-07-1A
3920
Metal particles
found in
Gearbox.
Did not document
Inspection of worm gear or
document
root
cause.
Contractor
Work.
The
ins'pector's
review of the
above
work packages
indicated that
contractor
oversight
was not effective to ensure
proper root cause
analysis
was performed,
and corrective
actions
were
implemented
in
maintenance
of Limitorque actuators,
maintenance
procedures
were not
available
for Limitorque actuators,
vendor
manuals
for Limitorque
actuators
were outdated
and not adequate,
and the
use of
a critical
part was not recorded
on
a work order.
Contractor
work
on
the
actuators
listed
above
was
accomplished
under
the
FPL quality
system,
as
implemented
by
procedure
PR/PSL-1
Revision
13,
"Control
of
Purchased
Material,
Equipment,
and Services."
When contract
personnel
perform work for
the licensee
on site,
under
the
FPL quality system,
this procedure
requi res "...adequate
supervi sion of work. This includes
observation
of work as appropriate,
review .of completed work documents,
signoff
for work completion,
and gathering
documentation
for gC review
and
file."
In addition,
the
"Journeyman'
Work Report"
in
each
work
package
requires
the journeyman to:
"Describe the trouble
found
and
your analysis
of the
cause
or reason."
An effective review of the
work packages
at the time of completion
would have
questioned
the
lack of
a
documented
root
cause
for the
worn valve
stem
which
required
replacement
(PWO 2570,
FPL Work),
and the
squealing
noise
from
the
valve
operator
(PWO
0212,
Contractor
Work) for valve
MY-09-09.
These
problems
may
have
been
precursors
to
the
- September
23,
1989,
event
as discussed
in paragraph
Z.a in which this
valve failed to operate
as
designed.
It should
be
noted that the
PWO's worked by contractors
which are listed above were reviewed
and
signed (in the supervisor's
block)
by
PSL contract administrators,
instead
of
experienced
discipline
supervisors.
Contract
administrators
are primarily responsible
for ensuring
the legal
terms
of respective
contracts
are
met,
and
may
not
necessarily
perform
technical
reviews of a contractor's
work, which may change
the
scope
of
a work order.
The licensee
indicated to the inspector that there
were
no procedures
that explicitly defined the duties of the contract
administrator.
Additional examples of lack of contractor oversight were noted
by the
inspector for other completed
Limitorque work; Unit 1 valve MV-09-13,
on
the
crosstie
between
the
two
motor
driven
auxiliary
feedwater'umps,
on
which
the
valve
stem
was
worn,
and
valve
MV-07-1A, the outlet valve from the Refueling Water Tank (RWT) to the
HPSI-LPSI-CS
which, contained
metal
chips in the Limitorque
gearcase.
The chips were from the brass
worm gear,
according to the
journeyman's
report,
and
may
have
resulted
from
a
number
of
conditions
which include
an improperly shimmed
lower thrust bearing,
or
higher
than
normal
actuator
required
because
. of
valve-related
problems.
'
As
indicated
in
paragraph
2.a,
Unit 2
Valve
MV-09-10 failed to
operate
as designed
because
of a worn limit switch pinion gear.
This
pinion gear
wore because
excess
axial clearance
was introduced
by an
upper
handwheel
which was approximately
0. 100" thicker than it
should
have
been.
Cognizant
licensee
personnel
indicated that this
was not furnished
by the actuator
vendor
and appeared
to have
been
fabricated
on site.
A thorough
review of work orders
by the
licensee,
however,
was
not
successful
in
determining
when
the
unauthorized
upper
handwheel
housing
was installed'PL
Administrative Procedure
0010432,
Revision
39 requires,
in part, that
"When parts
or materials
are
used,
attach all
ROS
(Received
on
Stores)
forms and/or
gC tags to the
NPWO package."
Contrary to the
above,
the licensee
was not able to account for the
use of the above
mentioned
gasket material
which was too thick.
This was identified
to the
licensee
as violation 50-335,389/89-29-01,
Failure to Follow
Procedures
for Material Control for Limitorque Maintenance.
3.
Exit Interview
The inspection
scope
and results
were
summarized
on December
1,
1989, with
those
persons
indicated
in paragraph
1.
The inspector described
the areas
inspected
and
discussed
in detail
the
inspection
results.
Although
reviewed during this inspection,
proprietary information is not contained
in this report.
Dissenting
comments
were not received
from the licensee.