ML17348A910
| ML17348A910 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 03/05/1991 |
| From: | Hunt M, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML17348A909 | List: |
| References | |
| 50-250-91-03, 50-250-91-3, 50-251-91-03, 50-251-91-3, NUDOCS 9103250172 | |
| Download: ML17348A910 (13) | |
See also: IR 05000250/1991003
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323
Report Nos.:
50-250/91-03
and 50-251/91-'03
Licensee:
Florida Power
and Light Company
9250 West Flagler Street
Miami,
FL
33102
Docket Nos.:
50-250
and 50-251
License Nos.:
and
Facility Name:
Turkey Point
3 and
4
Inspection
Conducted:
January
14-18 and February 5-7,
1991
Inspector:
nr
unt
Approved by:
M. B.
Shym oc
Chief
Plant Systems
Section
Engineering
Branch
Division of Reactor Safety
ate
igned
Date Signe
SUMMARY
Scope:
This special,
announced
inspection
was conducted
to review the current status
of the licensee's
Emergency
Power
System
Enhancement,
observe
cable pulling
operations
and
review of various
open
items
identified during
previous
inspections.
Results:
No major
weakness
were identified during this inspection, with the exception of
the following Noncited Violation, 50-250,
251/91-03-01,
Inadequate
Procedures
for Megger Testing.
(See paragraph
2.c)
The licensee's
power cable installation program was identified as
a strength in
that
care
was
taken to insure that the cables
are protected
during pulling
operations
and
any indication of
damage
was
immediately
evaluated
before
pulling operations
proceeded.
9203250172
910308
ADOCK 05000250
9
0
REPORT DETAILS
1.
Persons
Contacted
Licensee
Employees
P.
M. Banaszak,
Electrical Engineer
- W. Bladow, guality Assurance
(gA) Manager
- R. J. Daly, Outage
Manager
- S. T. Hale, Site Engineering
Manager
- M. P.
Huba, Engineering
- D. Jenkins,
Engineering, Electrical
Juno Plant Nuclear
(JPN)
- R. Kundalkar, Electrical
Enhancement
Project Engineer
- J. F. O'rien, guality Control
(gC) Superintendent
- L. Pearce,
Plant Manager
- T. Plunkett, Site Vice President
- D. R. Powell, Licensing Superintendent
- A. Zielonka, Technical
Department Supervisor
Other
licensee
employees
contacted
during this
inspection
included
craftsmen,
engineers,
technicians,
and administrative personnel.
NRC Resident
Inspectors
- G. A. Schnebli
"Attended exit interview
2.
Emergency
Power Systems
Enhancement
Status
Review
The inspector
reviewed with licensee
representatives
the status
of the
various
phases
of cable installation,
equipment installation
and testing.
a.
Cable Installation Review (55063)
The inspector
reviewed the licensee's
cable pull testing calculation
PTN-OFJE-90-0007
which established
the limits for pulling tensions
using
a
LUFF-EAZ "Mares Tail" to pull lead
sheathed
5
KV, Class
cables
when it is necessary
to pull cable in the middle of the cable
run.
This operation
involves wrapping the
mares tail around
the
outside of the individual conductor or around the group of conductors
if the pull is
made
up of more
than
one cable.
The sizes
and
tensions
are listed in the table below:
Number of
Conductors
Wire Size
Maximum Allowable
Pullin
Tension in LBS.
1250
KCM
1250
KCM
750
KCM
4/0
AWG
3000
4000
3000
3000
There
are
also certain
conditions
which must
be
met in order to
assure
that the cable's
not
damaged
during the pull.
There are
cautions
given to insure that the mares tail is installed properly so
that the tensions
are
not concentrated
in localized
areas
of the
cable.
The inspector
observed
portions of the pulling process
for cable
Number
4AD068 which consisted
of 3 1/C 750
KCN cables that were to be
pulled 'into
a conduit bank that runs
between
several
manholes.
Due
to the configuration of the manholes
and conduits it was necessary
to
pull portions of the cable into the conduits
and then pull cables
out
onto
a protected
area
and
then reenter
the conduits
leaving that
manhole
by pulling from the next manhole.
Due to the length of the
cable
run it required pulling portions of the cable
using
a mares
tail.
The
gC inspector
reviewed the entire pulling arrangement
prior to the
start of the pulling operation.
This included verification of the
calibration of the tensionmeter
used to measure
the pulling tension.
The tension
was monitored continuously during the pulling operation.
At no time did the pull tension
exceed
the calculated
(expected)
values
which were very conservative.
All personnel
involved in the
pulling operation
were knowledgeable
and understood
the requirements
and precautions.
In addition there
was
a commitment to High Potential
(HiPot) testing of these
cables
after installation to assure
that
no
damage
was
done to the cable insulating materials
during the pulling
operation.
During the inspection
the licensee
continued
the pulling activities
for the longest
cable
runs which are
manpower intensive
due to the
configuration of the
imbedded
conduits
and the limited lay down area
at each of the pull points.
The majority of the pulls are completed
for power cables
that will connect the
4B Emergency Diesel
Generator
(EDG) to the
4D switchgear.
These
were
the longest
cable pulls
(approximately
1007 feet)
and the largest size cables that will be
pulled.
There were
two pulls which involved three single conductor
750
KCM cables
each
and three pulls of single conductor
1250
KCM
cable.
As discussed
earlier the licensee's
program
appears
to
be
fully adequate
to accomplish
the cable pull effort in
a manner that
will result in proper cable installation.
Equipment Installation
(55053)
The Unit
4
and
the mechanical
support
equipment
have
been
installed.
The interconnecting wiring needed
to operate
the diesel
engines
is permanently installed.
The output
power cables
from the
EDG to the safety
busses
are being installed.
The permanent control
cables will be installed to permit
EDG testing to start in April.
,
The licensee
had committed to replace eight load center transformers
with air cooled transformers
to eliminate
PCBs.
This task
has
been
completed for Load Centers
3A, 3C,
4A and
4C.
The replacement for
the Load Centers
3B, 3C,
4B and
4C is inprogress.
The four new
EDG load sequencer
panels
are
now in place
and ini.tial
wiring has started.
Equipment Testing
The licensee originally intended to perform vendor tests
and portions
of the
4A and
4B
EDG preoperational
testing with the generators
tied
to
a
temporary
load
and their auxiliary equipment
being supplied
electrical
power from a temporary source.
This Phase
I testing
was
to include
35 successive
starts with
EDG 4B to be test first.
During the
performance
of Preoperational
test
Procedure
.0804.098,
EDG 4B System
Preoperational
Test
Phase I,
a failure of the pilot
exciter regulator
(PER)
was identified.
This circuit provides black
start capability for the
EDGs.
The circuit components
were
removed
from the
4A EDG for replacement
items but were also found defective.
Preliminary evaluation of the failures indicated that the
PER's
had
been subjected
to either
an over voltage or a reverse
bias condition.
Further investigation
by the licensee of onsite electrical testing of
the
generator
components
indicated
that
the circuit
component
failures were due to megger testing.
The
megger testing
was the result of the
change to the storage
and
testing requirements
of Plant Change/Modification
(PC/M) No.87-263,
New EDG's Installation,
which
was
revised
by Change
Request
Notice
(CRN)
No. M-2788,
called for meggering
of the
generator
field
coils while in storage.
However, these instructions did not consider
the various
vendor
manual
caution
and warning statements
to insure
that solid state
power and control circuits are electrically isolated
during insulation resistance
measurement
of the generator rotor pole
windings.
Once the problem
was identified the licensee
took actions to insure
that instructions for all
megger testing of components
and cables
were carefully
reviewed
and
vendor
instructions
for testing
are
observed.
This
item
is
identified
as
a
noncited
violation,
50-250,
251/91-03-01,
Inadequate
Procedures
for
Testing.
This
licensee
identified violation is
not being cited
because
criteria
specified
in Section
V.G. 1 of the
NRC
Enforcement
Policy
was
satisfied.
During testing of 4B
EDG a failure of the jacket cooling water header
occurred.
The
change
out of the
required
dismantling
a
portion of the
engine
which would delay the testing
and possibly
impact
on the testing
schedule.
The decision
to test
4A
EDG was
made.
The inspector
returned
to the site
on February 5-7 to observe
and
review the testing of 4A EDG.
However,
even
though
35 starts
were
accomplished
certain
components
(Pilot Exciter Regulatory)
were found
incorrectly
assembled
on
the
4A
EDG which
caused
the
licensee
representatives
to disqualify the first 16 starts later, after the
35
starts
had
been
completed.
Additionally, during the test requiring
five starts
without recharging
the starting air receivers,
an air
start motor failed.
While there
are four air start motors for each
engine
during
the test
two were intentionally valved out.
The
inspector
was
advised that the engine
did start with only the
one
starting
motor but the licensee
considered
in view of the overall
difficulties encountered
during this testing
phase,
decided that the
35 starts
would be redone after each
EDG was permanently
wired into
the plant systems.
3.
Action on Previous
Inspection
Findings
(92701,
92702)
(Closed) IFI 250,251/89-203-21,
Plant Operating
Diagram Errors.
This item
identified an error in the load shedding
diagram for the component cooling
water
(CCW)
pump 3B.
The logic indicated that the
CCW breaker would close
on load shedding
due to the loss-of-offsite power
(LOOP) when in actuality
the
breaker
should
be
opened.
There
was
also
an error identified
regarding
the start/stop
selection
switch for all
CCW pumps
except
pump
3B.
The licensee
has corrected
the load shedding logic in PC/M 90-157
and
90-158.
This item is closed.
(Closed)
IFI 250,251/89-203-22,
DC Ground Fault Administrative Controls,
This
item
requested
an
evaluation
of the
administrative
controls
addressing
the response
time to ground fault alarms.
Off Normal Operating
Procedures
9608. I
"125V
System
Location of Grounds"
and
9608.2
"Auxiliary 125V
DC System Location of Grounds"
have
been revised
and
now
require action
to isolate
a ground within four hours of receiving the
ground
alarm.
Instructions
are
included
which detail
the
steps
for
corrective actions required to isolate the grounded circuit.
This item is
closed.
(Closed)
250,251/89-203-23,
Acceptability of the
Minimum Battery
Terminal
Voltage.
This finding was
opened
due to the concern that the
minimum end-of-life battery
terminal
voltage
would not
be
adequate
to
power all safety related
devices.
The finding stated that the licensee
had not performed
a bounding calculation to
show that remotely located
devices
would oper ate at the minimum battery terminal voltages.
Therefore
adequate
assurance
did not exist that the combination of minimum battery
terminal
voltage
and
system
voltage
drop considerations
would yield
sufficient equipment voltages to maintain equipment functionally.
The licensee
stated
that there
was
no licensing
requirement for Turkey
Point to
have
a
bounding calculation.
However,
a purchase
order
was
issued
to
an Architect Engineering
(AE) firm to perform
a
DC Voltage
Drop Study to Demonstrate
Acceptability of Equipment
at
105V Minimum
Battery
Terminal
Voltage
and
is
scheduled
for
completion
by
March 2,
1991.
This item is closed.
(Closed)
Inspector
Followup
Item
( IFI) 50-250,251/90-42-01,
Potential
Early Failure of
Components.
This item has
been
upgraded
to
a
Noncited Violation identified
as
50-250,251/91-03
Inadequate
Procedures
for Megger Testing,
which is discussed
in this
report.
This item is closed.
(Closed)
Unresolved
Item 50-250,251/90-42-02,
Potential
for Inadequate
Control of Construction
Load
Causing
Loss of
AC Supply Circuit During
Initial
EDG 4B 24 Hour Endurance
Run.
During
a
preoperational
test of the
4B
on
December
12,
1990,
an
unknown problem caused
Load Center
3F breaker
31402 to trip.
The loss of
breaker
31402 resulted
in
a loss of power to Load Center
3F,
4F and
4G
since at the time these
load centers
were cross tied because
of a
4C 4 kv
bus
outage.
As the auxiliary equipment for the
4B
EDG was temporarily
powered from Load Center
3F breaker
31407,
the load center
outage resulted
in an aborted
4B
EDG test.
There
was
a concern that
a construction
load
had
been
added to the Load
Center
4G,
breaker
No. 41508 which
may not
have
been
authorized.
The
licensee
found that
breaker
31407
had tripped
on overload
current
as
evidenced
by the trip indicator.
Testing of the breaker trip device
identified
a problem with the long time trip element.
The trip device
appeared
not to have the capacity for starting currents
as would normally
be
expected
based
on the
as
found breaker setting.
Testing results
reviewed
by the inspector supported this conclusion.
In addition the licensee
identified the fact that breaker
41508
on Load
Center
4G had previously
been
a motor feeder breaker but was
now used to
supply construction
loads.
The breaker
had
been
used for construction
loads during previous
outages
and
was over looked during the development
of the breaker
control
program.
The licensee
has since
reevaluated
the
use of breakers for construction
loads
and
has developed
adequate
controls
for their use.
This item is closed.
(Closed)
Unresolved
Item 50-250,251/90-42-03,
Potential
Inadequate
M-K
Relay Design for EDG Solenoid Valves.
This item was identified at the end
of the
24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run
on the
4B Diesel
Generator
Load Test.
A Day Tank High
Level
Alarm was
received
that
when investigated
revealed
that the
solenoid
valve
on the
day tank fill line
was
open
(energized).
The
transfer
pump
had
shutdown
as
designed
but with the fill line valve still
open,
gravity flow from the storage
tank through the
pump
was occurring
thus
causing
the
day tank high level.
Further investigation
determined
that
an auxiliary relay in the fill shut off circuit had failed with the
contacts
closed
thus
keeping the fill line valve solenoid energized
in the
open position.
The licensee
and the
AE site engineers
determined that the contact rating
of the relay
had
been
exceeded.
The corrective action through
a design
change
replaced
the relay with one having
much higher contact ratings
and
installing a suppression
diode in the solenoid valve circuit.
In addition,
all the other circuits using the
same type relay that failed were reviewed
to check for current that would exceed
the relay contact ratings.
No
. other relays
in solenoid
valve circuits in this control
system supplied
with the
EDGs were identified that would exceed
the relay contact rating.
4.
Exit Interview
The
inspection
scope
and
results
were
summarized
on
January
18
and
February 7,
1991,
with those
persons
indicated
in paragraph
1.
The
inspector
described
the
areas
inspected
and
discussed
in detail
the
inspection results listed below.
Proprietary information is not contained
in this report.
The inspector identified the noncited Violation 50-250,
251/91-03-01,
Inadequate
Procedures
for Megger Testing.
Dissenting
comments
were not received
from the licensee.