ML20057B421
| ML20057B421 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 09/10/1993 |
| From: | Girard E, Julian C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20057B419 | List: |
| References | |
| 50-302-93-18, NUDOCS 9309220003 | |
| Download: ML20057B421 (31) | |
See also: IR 05000302/1993018
Text
___
. . _ _
__ __.-
_
_
_ ..
.
..
/ p neo %
UNITED STATES
.
NUCLEAR REGULATORY COMMISSION
-k
[*
'
REGION 11
%
101 MARIETTA STREET, N.W., SUITE 2900
7,;
- p
ATLANTA, GEORGIA 30323-0199
'+,,
d
q
.....
,
i
'
Report No.:
50-302/93-18
)
Licensee:
Florida Power Corporation
!
3201 -34th Street, South
,
St. Petersburg, FL 33733
Docket No.: 50-302
License No.: DPR-72
l
l
Facility Name: Crystal River 3
j
Inspection Conducted: June 28 - July 30, 1993
Lead Inspector:
bil
9
T
i
E. Girard,~ Team Leader
Date Signed
'
!
Other Inspectors:
1
I
P. Fillion, Reactor Inspector
.
M. Miller, Reactor Inspector
!
J. Haller, Contractor
Approved by:
V
hm
b
i
C. Julian, Chief
g
/Date 41gned
'
Engineering Branch
!
Division of Reactor Safety
'
i
i
EXECUTIVE SUMMARY
This special, announced, inspection assessed the capacity of the Electrical
,
i
Distribution System (EDS) to perform its intended safety functions.
It was
concluded that the EDS, had adequate capacity to perform its intended safety
functions. However the reliability of one 4160-480 V transformer was
j
questioned based on the plant's history of failures of similar transformers
(Inspector Followup Item 302/93-18-04).
[ Note: This inspection did not
.
,
include some aspects of the EDS, see Section 1.0]
Other adverse findings included two violations, one unresolved item, four
4
additional inspector followup items, and a gereric matter previously
identified at other plants. The more significant findings were deficient
'
design engineering inputs to new proposed Technical Specifications (Inspector
j
Followup Item 302/93-18-05) and to the battery service test procedure
(Violation 302/93-18-01), and findings that questioned the adequacy of testing
i
used to assure devices would receive sufficient voltage (Unresolved Item
!
302/93-18-03).
i
>
9309220003 930930
C
-
hDR
ADOCK 05000302 kj
]
k
i
-
- - _
_
!
.
..
!
'
'
>
ii
!
l
Summary descriptions of the inspection findings are given below. The inspec-
tors noted a number of strengths and these are listed following the descrip-
l
tions of the adverse findings. Also, a previously identified inspector
'
followup item was examined and closed through this inspection and it is listed
e, the conclusion of the executive summary.
'wo Vio.lations Identified:
(1) Violation 302/93-18-01, Application of Voltage Analysis Results to
Battery Service Test.
The licensee failed to assess and correct the battery service test
procedure following completion of a calculation that indicated
j
higher battery voltages were required than previously considered
l
necessary. The inspectors considered this to represent deficient
i
design control. (Section 2.4.1)
(2) Violation 302/93-18-02, Motor Control Center Breakers, Thermal
Overload Device, and Breaker Settings Not in Accordance with Draw-
ings.
,
The sizes of two breakers and a thermal everload device and the
settings for several breakers did not conform with the applicable
drawings. (Section 3.2)
One Unresolved Item Identified:
Unresolved Item 302/93-18-03, Adequacy of Testing Used to Demonstrate
Devices Receive Sufficient Voltage.
The licensee's calculations determined that the voltage to many 120 VAC
and 125 VDC devices was below the minimum pick-up voltage requirement
!
indicated by the device manufacturers. The licensee used limited
testing to demonstrate pick-up below the design supplied voltages.
It
did not appear that factors such as population variability and aging
were adequately addressed through the testing performed. Acceptable
,
I
criteria for establishing device capabilities through testing will be
!
internally evaluated by the NRC. Upon completion, the licensee's use of
testing will be re-examined.
(Sections 2.3.3 and 2.4.2)
Five Inspector Followup Items Identified:
(1) Inspector Followup Item 302/93-18-04, Increased Vulnerability Due to
Delay in Replacement of Potentially Degraded Engineered Safeguards
Transformer.
l
Two safety-related (engineered safeguards) and six nonsafety-related
4160-480 V ventilated dry type transformers are utilized by Crystal
River 3.
In the 1989/1990 time period three of the eight transform-
ers failed, one safety-related and two nonsafety-related.
In a
failure analysis completed in 1990 the licensee attributed the
l
failures to the age of the transformers (about 15 years in service)
.
.,
,
,
'
i
.
iii
and determined that the five remaining transformers (also in service
for 15 years) should be replaced. All but the safety-related
transformer were subsequently replaced.
Its replacement was increm-
entally delayed and, as of this inspection, was reportedly planned
for spring 1994. The delay appears to have been primarily based on
avoiding any extension of planned outages.
(Section 3.6)
(2) Inspector Followup Item 302/93-18-05, Incorrect Values in Proposed
New Technical Specifications.
The licensee's new proposed Technical Specifications were only
examined relative to two requirements.
In both cases errors were
identified by the inspectors:
(a) Surveillance Requirement 3.3.8.2 specified 0 V as the setpoint
i
for the undervoltage relay. A higher value, such as the 2334 V
currently prescribed in the licensee's relay setting procedure,
should be specified.
(Section 2.3.2)
(b) Surveillance Requirement 3.8.6.1 specified a minimum electro-
lyte temperature of 60 degrees _F for battery operability. The
inspectors found that the battery sizing calculation had been
l
based on a minimum electrolyte temperature of 70 degrees F for
operability of the battery.
(Section 2.4.3)
i
(3) Inspector Followup Item 302/93-18-06, Review of Ampacity Analysis
for Electric Penetration Conductors.
_
l
i
The licensee did not have an ampacity analysis for penetration
conductors. This omission had already been identified by the
.
licensee and several 480 V power circuit penetrations had been
1
evaluated to demonstrate acceptable ampacity and short-circuit
withstand capability.
It is the inspectors' understanding that all-
l
penetration conductors will be analyzed.
(Section 2.5)
(4) Inspector Followup Item 302/93-18-07, Lack of Preventive Maintenance
Inspection of Power Line Mechanical Connections to the Turbine
Building.
The licensee had not scheduled or performed any preventive mainte-
nance inspection of the 230/500 kV power line connections at the
turbine building. The concern is that the mechanical integrity of
the connections could degrade over an extended period of time and be
lost during high winds or a seismic event.
l
!
l
!
i
l
!
.
.
.
-
.
. -.
-
.
--
___
l
.
..
,
,
iv
(5) Inspector Followup Item 302/93-18-08, Lack of Preventive Maintenance
Inspection of Motor Control Centers.
There was no scheduled periodic preventive maintenance inspection of
.
the motor control center motor starters, cubicle stab connections,
l
bus bars, and panel bottoms to identify any build up of dirt or dust
or any deterioration that might be a fire hazard or impair opera-
tion.
(Section 3.4)
Generic Matter Identified:
The inspectors observed that the licensee did not perform any testing to
verify the continued adequacy of molded case circuit breakers. A
similar apparent weakness has been identified at other plants and is
being reviewed internally by the NRC.
It is anticipated that any
corrective action required as a result of the internal NRC review will
be applied generically to plants. Therefore, the matter is not being
identified for specific followup at Crystal River.
(Section 3.4)
Strenaths Identified:
In addition to the above matters of concern, the inspectors also noted
strengths or positive findings.
Examples included:
Except as noted above, calculations were well done.
The licensee was able to readily provide information in support of the
calculations.
The engineers contacted appeared well involved and knowledgeable.
MCCs were generally clean and in good condition, considering the age of
the plant.
Many actions had been taken recently to improve or better ensure the
adequacy of the EDS.
Examples included the installation of the BEST
transformer, calculation upgrades, new batteries, etc.
Inspector Followuo Item Closed:
,
l
l
Inspector Followup Item 302/92-18-01, Battery and Battery Charger
Issues.
i
.
..
.
.
TABLE OF CONTENTS
Pace
EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
1.0
INTRODUCTION
I
..........................
2.0
ELECTRICAL SYSTEMS DESIGN . . . . . . . . . . . . . . . . . . . .
I
2.1
Con cl u si on s . . . . . . . . . . . . . . . . . . . . . . . .
3
)
2.2
Offsite Power . . . . . . . . . . . . . . . . . . . . . . .
3
2.3
AC Systems
5
........................
2.3.1
Control Logic for 4160 V Breakers
5
.........
2.3.2 Power Sy: tem Voltage . . . . . . . . . . . . . . . .
6
2.3.3 Control Circuit Voltage
8
..............
2.3.4 System Short-Circuit Duty
11
.............
2.3.5 Protection and Coordination
11
............
2.4
DC Systems
11
........................
i
2.4.1
Battery Service Test . . . . . . . . . . . . . . . .
12
i
2.4.2 Control Device Minimum Operating Voltages
13
.....
2.4.3 Minimum Battery Electrolyte Temperature
13
......
2.5
Containment Electrical Penetrations . . . . . . . . . . . .
14
3.0
MAINTENANCE, TESTING, CALIBRATION, AND CONFIGURATION CONTROL
15
..
i
l
3.1
Conclusions . . . . . . . . . . . . . . . . . . . . . . . .
15
l
3.2
Equipment Walkdown Inspections
16
..............
l
3.3
C al i brat i on . . . . . . . . . . . . . . . . . . . . . . . .
18
3.4
Preventive Maintenance for Electric Equipment . . . . . . .
19
3.5
Fuse Control
21
.......................
3.6
Transformer Failures
21
i
...................
4.0
INSPECTOR FOLLOWUP ITEM . . . . . . . . . . . . . . . . . . . . .
23
l
l
5.0
EXIT INTERVIEW
24
.........................
l
APPENDICES
Appendix A: Acronyns and Abbreviations
25
............
Appendix B:
Persons Contacted
26
.................
,
I
I
_ _ _ _ - _
_ _ _ _ _ _ _ _ _ _ _
.
. .
,
4
.
1.0
INTRODUCTION
The objective of this inspection was to assess the capacity of the
Electrical Distribution System (EDS) to perform its intended functions.
The inspection was conducted using guidance provided in NRC Temporary
Instruction 2515/107, " Electrical Distribution System Functional
Inspection (EDSFI)", issued October 9, 1990.
However, the scope of the
inspection was reduced to limit coverage of areas which had recently
been inspected or would be addressed in a planned future inspection of
engineering and technical support. Areas which did not receive detailed
inspection were as follows: engineering and technical support, diesel
load rating and voltage regulation, design and testing of mechanical
l
support systems, battery sizing, DC short-circuit analysis, switchgear
!
sizing, and diesel testing.
In addition, tha inspectors did not
evaluate either the licensee's ongoing actions to resolve a previous
violation regarding cable separation or the emergency diesel generator
l
loading issues that are under discussion with the NRC Office of Nuclear
l
Reactor Regulation.
l
The design, installation, maintenance, and testing of the EDS were
l
examined for conformance with the General Design Criteria, other
regulatory requirements, and commitments stated in the FSAR.
Standard
engineering and industry practices were considered in examining plant
design and maintenance.
This report identifies violations of regulatory requirements and other
findings. All are described in the text that follows.
In addition, the
l
violations and other significant findings are listed and briefly
)
described in the executive summary at the beginning of this report.
2.0
ELECTRICAL SYSTEMS DESIGN
The inspectors evaluated the capacity of the Electrical Distribution
i
System (EDS) design to perform its intended safety functions through a
'
review of design criteria, calculations, drawings, and equipment
capabilities and settings data, aided by related discussions with
licensee personnel and observations of the installed equipment.
Brief
descriptive information on the EDS is provided below.
j
There are five major generating units at the crystal River site, one
nuclear and four fossil. The nuclear unit a,d ene fossil unit generate
into the 500 kV grid. The other three fossil units generate into the
230 kV grid. The nuclear unit, designated Crystal River 3 (CR3),
receives offsite power from the 230 kV grid through the 230 kV switch-
yard. The power to this switchyard is provided by five transmission
lines, as well as from the generators of the three fossil units already
mentioned. The 500 and 230 kV grids are tied together at the Brookridge
substation, a short distance from the Crystal River site.
Two feeders from the 230 kV switchyard supply preferred offsite power to
CR3 for emergency operation through two separate 230-4.16 kV engineered
safeguards (ES) transformers. One of these transformers is located in
the 230 kV switchyard and is referred to as the Offsite Power
Transformer. The other is located adjacent to the Turbine Building and
!
i
a
e s
2
is referred to as the Backup Engineered Safeguards Transformer (BEST).
Each of the two transformers is sized to carry the ES loads of either or
both buses. There are two train oriented engineered safeguards 4.16 kV
buses (3A and 3B).
In addition to the 230-4.16 kV ES transformers already mentioned, CR3
has two transformers which are used to power nonsafety loads. These are
the 230-6.9-4.16 kV Start-up Transformer and the 22-6.9-4.16 kV Unit
Auxiliary Transformer. The former is fed from the 230 kV switchyard.
The latter is fed from the CR3 22 kV generator during operation and is-
i
backfed from the 500 kV substation 500-22 kV transformer (with generator
i
links removed) during outages.
It may be ur,ed to supply the ES busses
(backfed from the 500 kV substation) during outages.
The Start-up
Transformer does not normally supply the ES busses but may do so through
replacement of linkages that are normally removed. The Start-up and
Unit Auxiliary Transformers each have two isolated secondary windings,
one rated 6.9 kV and the other rated 4.16 kV. The 4.16 kV windings feed
,
l
various pumps and other nonsafety loads.
The 6.9 kV windings power the
Reactor Coolant Pumps (RCPs) and a 6.9-4.16 kV transformer which feeds
the RCP bus switchgear.
The 4.16 kV ES busses power large safety-related pumps directly.
Various smaller loads are supplied through stepdown transformers, load
centers, motor control centers, chargers, and inverters. The emergency
load voltage ratings are 480 and 120 VAC, and 250 and 125 VDC.
In the
event of a loss of offsite power or excessively degraded voltage, each
i
4.16 kV ES bus is powered from a 2850 kW diesel generator (emergency
J
standby power).
i
The CR3 Class 1E DC System includes two separate and independent 250/125
VDC systems.
Each system is redundant and includes a battery bank of
.
116 lead-acid type cells connected in series, with a center tap, to
!
accommodate two 125 VDC subsystems as well as a 250 VDC subsystem. This
l
design provides 250 V for DC motors and 125 V for DC control circuitry
l
and is the backup supply to the 120 VAC vital power system inverters.
i
Normal power supply to each 125 VDC subsystem is provided by a separate
l
125 V battery charger. A spare 125 V battery charger is provided for
i
each redundant system. These three battery chargers for each redundant
system are supplied from a separate system of the unit's 480 VAC Class
1E systems. The batteries serve as backup power supplies upon loss of
Class IE 120 VAC power or loss of battery charging capability.
The CR3 Class 1E 120 VAC vital power systems consist of four separate
and independent systems.
Each system includes an uninterruptible power
supply (UPS) subsystem served by an inverter and a non-UPS subsystem
served only by a regulating transformer. The vital power systems supply
Class 1E power to vital instruments and controls. Normal power supply
to the UPS is from the 480 volt Class IE systems with backup via
uninterrupted transfer, within the inverter circuitry, to the 250/125
VDC Class IE systems.
In addition to the inverter, each UPS subsystem
has an alternate supply via a regulating transformer. High speed static
switches, for the UPS subsystems, were provided to allow switching
.
. ,
ll
3
between the inverter and alternate power supplies.
The power supply to
the non-UPS subsystem's regulating transformers is also the 480 V Class
IE systems.
2.1
Conclusions
l
The present design capabilities of the EDS were considered ade-
j
quate. However, a concern was identified regarding testing relied
on to establish that certain safety-related 120 VAC and 125 VDC
control devices (typically relays) would pick-up at design voltag-
es.
It was not clear that the test results assured adequate
performance of the installed devices. The inspectors found that,
i
by removing conservatisms from AC control circuit calculations,
the supplied voltage levels appeared acceptable without reliance
on testing. The acceptability of the licensee's use of testing is
identified as Unresolved Item 302/93-18-03. Additional details
are described in Sections 2.3.3 and 2.4.2.
Based on two additional findings, it appeared that the licensee
'
did not have adequate design engineering inputs to new proposed
Technical Specifications (TSs) and to the battery service test
procedure. The inspectors only examined two requirements in the
proposed new TSs and in both instances apparent errors were
discovered.
Inspectors found that the value of minimum battery
electrolyte temperature in the new TS is not supported by engi-
,
neering calculations. A 1992 calculation had found that battery
'
final terminal voltages of approximately 111 volts were required
for emergency loads; however, engineering failed to verify that
"
the acceptable voltage given in the battery service test procedure
was consistent with the calculated voltage requirement. The
former finding is identified as Inspector Followup Item 302/93-18-
05 and is described in Sections 2.3.2 and 2.4.3.
The latter is
1
identified as Violation 302/93-18-01 and is described in Section
)
'
2.4.1.
i
One further design-related finding was identified. The licensee
,
'
had not analyzed all of the electrical penetration conductors.
This had been recognized by the licensee and actions had been
implemented to complete the analyses. The inspectors concluded
3
~
that the importance of this analysis justified NRC verification
and it was identified as Inspector Followup Item 302/93-18-06.
'
This item is described in Section 2.5.
2.2
Offsite Power
,
Voltage control of the offsite power system was affected by a
combination of capacitor switching and generator excitation
adjustment. Normally the Crystal River 230 kV bus is maintained
between 242 and 238 kV. The dispatcher receives an alarm when the
voltage drops below 238 kV. To provide analytical margin, 236.4
kV was used for CR3 auxiliary system voltage calculations, and
'
243.6 kV was used for short-circuit calculations.
,
i
. ,
,
'
j
4
\\
'
The 230 kV bus that supplies the safety-related loads at Crystal
1
River was quite stable during electrical transients such as those
which would accompany tripping of the nuclear unit. This was a
result of the bus being directly supplied from the generators of
the three fossil units at Crystal River. To confirm the stability
of this "offsite" power, the licensee's transmission planning
engineers calculated the following case: emergency tripping of the
generator breakers for CR3 with system load at the expected summer
peak for year 1994, CR3 generating 200 mVAR, CR4 (the largest
fossil unit which generates at 230 kV) shutdown, and the strongest
230 kV line out of service. The electrical system model used in
the calculation was derived from a regional utility group data
bank and had been recently validated. The calculation results
indicated that the minimum voltage at the Crystal River 230 kV bus
would be 236.4 kV approximately 0.8 seconds after the unit trip.
i
Voltage settled cut to 238.5 kV at about 6 seconds. This
l
indicated the offsite source was reliable and stable. The minimum
i
voltage was consistent with the auxiliary system voltage
calculations.
'
l
Voltage at the various transmission system buses was maintained by
a combination of automatic means and dispatcher actions. The
'
dispatcher depends on voltage readings at his station which are
,
transmitted from the remote locations. The inspectors requested
the licensee to state the overall instrumentation loop accuracy
for this r: Pg.
In response, the licensee provided the accuracy
of each component in the loop. Total cumulative error was less
than one percent, so the voltage readings at the dispatch office
,
are sufficiently accurate to allow the dispatcher to control
l
voltage at the CR3 switchyard within the stated narrow band (242 -
l
238 kV). The inspectors obtained the model number of the poten-
l
tial transformer by field inspection and verified the accuracy
reported by CR3 was consistent with the accuracy reported by
another utility for the same model.
1
The FSAR, on page 8-3, states that a power system stabilizer was
!
installed on the main generator of CR3. At the time of this
inspection, the stabilizer was disabled. The transmission plan-
ning engineers stated that the stabilizer was functional at one
time. However, they were unable to tune the stabilizer to their
complete satisfaction. Meanwhile, overall system configuration
changed to the point where the stabilizer was no longer needed.
Therefore, it was disabled. The licensee presented an internal
FSAR change request that had been prepared before the inspection,
which deleted reference to the stabilizer.
The FSAR, on page 8-5, states that the reactor coolant pumps are
n1rmally fed from the unit auxiliary transformer.
In actuality,
fo many years, the reactor coolant pumps were normally fed from
the start-up transformer. The licensee presented an internal FSAR
chaige request that had been prepared before the inspection, which
propirly described the alignment of the reactor coolant pumps.
!
.
_ _
,
. _
.
._.
l
4
.
.
,
.
.
5
l
1
i
2.3
AC Systems
2.3.1 Control Logic for 4160 V Breakers
j
The inspectors evaluated the control logic for. circuits that
control the incoming breakers to the safety-related 4160 V buses.
The proper functioning of these circuits is critical to meeting
the design basis of the safety-related systems. There are four
incoming breakers to each safety-related bus as summarized in the
following table:
TRAIN A SUMMARY
(Train B similar)
'
Breaker
Power Source-
Drawino No.
3205
Backup Engineered
MT-09'
Safeguards Transformer
3207
Unit Auxiliary
MT-11
l
'
Transformer
3209
Diesel Generator
MT-13
3211
Offsite Power
MT-15
Transformer
Other drawings needed to understand the logic are those that
describe the emergency diesel generator ready matrix, protection,
_
loading sequence, and undervoltage protection circuitry.
A typical motor feeder breaker control circuit was also reviewed.
'
The logic-for these was quite-simple: An undervoltage signal trips
the breaker and an Engineered Safeguards Actuation Signal closes
the breaker.
Some of the more important nuclear plant design criteria for
,
incoming breaker control logic are:
I
Automatically transfer from the offsite power source to the
diesel generator within the appropriate time interval upon a
degraded voltage or undervoltage condition.
Prevent paralleling of the two diesel generators.
-
Prevent interconnection of trains A and B.
Prevent connecting a power source to a faulted bus.
Prevent paralleling two live sources unless they are syn-
chronized.
- -
-
- -
.
.
-
. - -
. - - - .
--.
.
. - .
-_
.
.
.
,
e
.
6
Trip open when faults on the bus or other adverse conditions
in the diesel generator or main generator are detected by
the protection system.
Fast transfers between the unit auxiliary source and the
offsite source at CR3 are not required, and in fact should
be avoided.
Logic does not include any circuitry that is not necessary.
Protect the diesel generator safety function in the eventu-
ality that a loss of offsite power should occur while the
diesel generator is being run in parallel with the offsite
source.
The inspectors found that all of the above design criteria-were
met. The only weakness identified was that _the 3205, 3207 and
3211 breaker control circuits provided for only manual synchroniz-
ing. This comment applies to train B as well. This means that a
live bus transfer using these breakers would not be supervised by
a synchrocheck relay. A synchrocheck relay takes some of the
burden off the operator when making a live bus transfer.- Without
the relay the operator must manually assure that the two sources
are in synchronism. Conceivably, the live bus transfer would have
>
to take place at a critical time such as transferring back.to
offsite power from the diesel generator during an accident condi--
tion when only one train was available.
In this case' to parallel
the two sources when they are greatly out of synchronism could
i
cause loss of electric power to engineered safeguards equipment.
2.3.2 Fower System Voltage
i
The inspectors reviewed electrical load flow calculations to
l
verify they demonstrated that adequate offsite power was provided
for AC equipment to perform its safety functions. The calcula-
l
tions demonstrated that equipment operating at the 480 V level and
!
above received adequate power. Appropriate degraded and. loss-of-
voltage relay settings were also verified. However, the inspec-
tors found that proposed new Technical Specifications specified an
inappropriate loss-of-voltage relay setting value. Additional-
details-are given in the paragraphs that follow. Concern regard-
ing the adequacy of voltages provided to devices in control
circuits operating at the 120 VAC level is described in Section
2.4.
Calculation E-90-0077,'Rev.1, dated December, 1992, determined
steady state voltages throughout the AC distribution system for
anticipated accident and operating conditions.
It was used to
demonstrate that safety loads would receive satisfactory voltage.
The inspectors' reviewed the computer program data base for the
calculation and verified that:
1
-
_ . _ _
.
_
.
-._ _
_.
_
_ ._
_
_ _ . _ _
-
.,
,
.
.
7
The input data for the transformers were correct.
'
The methodology for input data for cables was correct.
The load values were correct.
The steady state program modeled all motors. Most of the input
data had been confirmed by the licensee through field inspections.
Engineers who checked the calculation were interviewed by the
inspectors and stated that each ' individual data entry was checked.
From the calculation results, the inspectors found that adequate
"
steady state voltage was provided.
l
Calculation E-91-0018, Rev. O, dated December,1991, calculated
.
I
the transient voltage throughout the system following an engi-
'
neered safeguards actuation signal. The program also calculated
the acceleration time of the starting loads.
Following the
actuation signal the load blocks are added to the bus at five-
second intervals. Therefore, the motors must reach rated speed
l
less than five seconds after energization. The system model for
the motor starting calculation was copied from the steady state
calculation. The motor starting calculation did, however, require
additional motor and load characteristic data to be entered into
the data base, and the methodology for this was confirmed by the
inspectors. The calculation results showed that motors reached
rated speed within the specified time interval.
Calculations E-90-0077 and E-91-0018 also formed the basis for
setting the degraded grid protection relays.
Relays used for
l
degraded grid protection were solid state definite time relays
arranged for three-out-of-three logic. They were set to operate
at 3952 V with decreasing voltage. The time delay was set at 5
seconds. The relay output contacts were used with other logic and
timers to initiate automatic actions.
The relays reset at 3952 V
with increasing voltage. The calculated minimum accident scenario
steady state voltage at the 4 kV safety-related bus was 4161 V.
The minimum allowable voltage at the 4 kV safety-related hus was
calculated to be 3933 V.
Comparing the setpoints to the system
voltages, the inspectors confirmed that the degraded grid voltage
,
relays had optimum settings. The inspectors confirmed the
setpoints from the licensee's calibration data sheets.
In addition to the degraded grid relays referred to in the
previous paragraph, undervoltage/overvoltage relays had been
installed to protect motors and to ensure that there was suffi-
cient voltage for satisfactory system operation when offsite power
was being lost.
Inverse-time induction disc relays arranged in a
two-out-of-three logic were used for this function. The undervol-
tage contact had a pick-up setting of 2334 V.
The time setting
was selected such that the relay would operate at 7.8 seconds
after a sudden complete loss of voltage. The undervoltage relay
would initiate transfer to the emergency diesel generator faster
_
-
.,
,
.
.
8
than the degraded grid protection relay for certain ranges of non-
,
accident undervoltage conditions. The inspectors evaluated the
j
undervoltage relay settings and concluded they were adequate. The
uvervoltage contact was used by the logic as a reset signal and
its setting was also found adequate.
4
l
The voltage relays did not have an associated calibration test
specified in the present approved Technical Specifications.
However, proposed new Technical Specifications, which had been
submitted to the NRC for approval, did specify a calibration test
and the requirements were reviewed by the inspectors.
Surveil-
2
lance Requirement 3.3.8.2 described a channel calibration for both
4
the voltage relays. The Surveillance Requirement specified 4
setpoint of 0 volts for the loss-of-voltage undervoltage relay
rather than the 2334 volts setpoint which was being used by the
licensee in their present calibration procedure.
The inspectors
informed the licensee that the proposed TS requirement was in
error and should be revised.
Persons within NRR responsible for
reviewing Technical Specifications were also informed. This
,
i
matter is identified as Inspector Followup Item 302/93-18 05,
Incorrect Values in Proposed New Technical Specifications.
4
Another example is given in Section 2.4.3 below. The incorrect
values are of concern because the inspectors only reviewed two of
the requirements in the new proposed TSs and in both instances
errors were found. This appears to indicate inadequate engineer-
ing involvement in the development of the TSs.
In summary, the inspectors carried out sufficient review of the
power system voltage calculations to ensure that the 4160 V and
>
!
480 V loads received quality power when powered from the offsite
source during design basis steady state conditions and that
safety-related equipment could be successfully started from design
basis initial conditions. A concern was identified regarding
i
incorrect values given in proposed new TSs, as described in the
l
previous paragraph. Voltage requirements for AC control circuits
which derive their power from the 480 V distribution system were
addressed by the licensee in a separate calculation which is
discussed in the next section of this report.
,
I
2.3.3 Control Circuit Voltage (120 VAC)
The inspectors reviewed the control circuit calculation, E-91-
0012, to determine whether it demonstrated that control circuit
4
end devices, such as relays and motor contactors, would receive
adequate voltage to perform their safety functions. The calcula-
'
I
tion identified relays which did not receive adequate voltage and
recommended corrective modifications.
In reviewing the calcula-
tion, the inspectors found that it relied on testing to establish
minimum pick-up voltage limits for some safety-related relays.
.
_
.
d
'
9
'
i
The inspectors performed a simplified calculation on control
l
circuit MVP-2B for a lube oil pump to assess the computational
)
accuracy of the licensee calculation.
Their results were consis-
j
tent with those documented in calculation E-91-0012.
.
.
As already noted, calco ation E-91-0012 ioentified control circuit
deviceswhichreceivedIessthanspecifiedminimumvoltage
ratings.
This was reported to the NRC in Licensee Event Report
92-10, dated July 3,1992. Modifications were implemented by the
'
]
licensee to assure that the most critical control circuits
received adequate voltage.
The inspectors confirmed the implemen-
j
tation of two of these modifications. They verified that control
power transformers at motor control center 3Al for circuit DHV-5
l
and at 3A2-2A.for circuit CHP-1A were changed from 130 VA to 250
VA. The inspectors reviewed documentation to determine whether
all " problem" circuits had been addressed. Recommended modifica-
tions to correct voltage problems in eleven safety-related
circuits were found to have been deferred until Refueling Outage
9, scheduled for spring 1994.
The inspectors reviewed each of
1
these circuits to confirm the licensee's conclusion that deferring
-
the modifications did not have any adverse impact on plant safety.
The inspectors rev'.ew of E-91-0012 found that calculated voltages
to many control t'evices, such as relays, were as much as 13 volts
less than the minimum pick-up voltage determined from information
provided by manuncturers. The licensee used testing at lower
'
voltages in place of manufacturers pick-up ratings to establish
acceptablc operation at the design voltages. Most tests were
understood to have been performed on stock samples rather than on
installed devices. The sample tested was small and the licensee
offered no statistical basis for considering the stock samples
representative of installed devices.
Even where installed devices
were tested, factus such as changes from aging could not be
addressed. The considerations that went into establishing the
manufacturers' ratings had not been clearly identified or
addressed.
Because of their concerns regarding the licensee's use of limited
testing to establish minimum pick-up voltages, the inspectors
conducted further review of the circuits that had been accepted
based on the testing. This review led to a conclusion that the
'
devices in this category received voltages higher than originally
calculated and that reliance on testing was unnecessary.
Reasons why the calculation indicated that many devices received
less than published rated voltage when actually they received more
are:
The calculation used a source voltage which corresponded to
the degraded grid protection relay set point at the time the
calculation was initiated. The set point has since been
raised, so a higher source voltage would be available.
-
.
.
,
.
.
l
10
The applicable control power transformer regulation curves
indicated that the open circuit voltage ratio is 460-126
rather than the 480-126 used in the calculation.
(Note:
Before using the 460-126 value in an official calculation
the value should be confirmed by test and/or by the manufac-
turer.)
Some relays had their continuous rated voltage given as a
range, say 110-120 V.
According to NEMA Standard ICS
2-1988, Industrial Control Devices, Controllers and Assem-
)
blies; if the rating of the operating coil is given as a
voltage range, the coil can close successfully at 85 percent
of the lower voltage. Therefore, the 110-120 V coils are
designed to operate at 93.5 V, while the calculation results
were based on 85 percent of 120 V - 102 V.
The circuit for DHV-34, a decay heat system valve, has an
auxiliary relay. During inrush condition, the contactor
received sufficient voltage to pick-up (rated 87.6 V) but
j
the relay received 13 V less than its 102 V rating. The
circuit was re-analyzed for the condition where the
l
contactor had transferred to steady state conditions and the
relay then received 106 V.
So the circuit actually never
t
was a problem.
Twenty-six control circuits were individually reviewed in light of
1.he abeve. The calculations were revised (preliminary) and each
- ircuit was acceptable without using device pick-up values based
an testing. The inspectors considered these circuits representa-
tive of the great majority of control circuits. Therefore, it
should not be necessary to rely on testing to verify that the
devices receive adequate voltage.
In summary, the inspectors found that the basic methodology and
accuracy of the AC control circuit voltage analysis was correct.
'
Each circuit was detailed and there was very limited use of
simplifying assumptions. However, the conclusion in the official
i
calculation of record as to whether the calculated voltages to
devices were acceptable was based on questionable reliance on site
testing of the relays for many circuits.
This analytical
methodology was questionable.
However, re-examination of the
circuits in question during the inspection indicates that all
circuits may provide acceptable voltage without reliance on the
testing. The licensee did not agree to formally revise the
l
existing calculation, taking the position that the testing method-
'
ology was proper.
The NRC will evaluate criteria for use of tests to verify device
capabilities. Upon completion of this evaluation, Region II will
re-assess the licensee's use of testing te justify acceptable
device operetion.
Pending completion of aese actions this matter
is identified as Unresolved Item 302/93-1 -03, Adequacy of Testing
_
__
'
.
.
,
'
.
'
11
Used to Demonstrate Devices Receive Sufficient Voltage. A similar
concern regarding testing of devices for DC control circuits,
discussed in Section 2.4.2 of this report, will also be identified
to this item.
2.3.4
System Short-Circuit Duty
The inspectors reviewed the licensee's short-circuit calculatier.
E-90-0044, Rev. 2, dated August 14, 1992, to assess the adequacy
of the fault duty withstand and interrupting capabilities of the
equipment applied. The calculation was performed using the
computer program "AFault-1000".
It indicated that equipment had
been applied within ratings.
In the case of 480 V switchgear and
480 V load center transformers, the margin between equipment
capabilities and calculated fault levels ranged from approximately
one to five percent. However, the inspectors observed that the
j
calculation considered an extremely conservative system configura-
tion wherein power was supplied from the start-up transformer
'
which would allow the large nonsafety-related motors to contribute
to a safety-related system fault.
Since the "BEST" transformer
was installed to serve only the safety-related buses, their
connection to the start-up transformer is no longer used. Thus,
nonsafety-related motors would no longer contribute to a safety-
related system fault and the margins would be improved. On this
j
basis and other conservatisms used in the calculation, the
inspectors concluded that the equipment was not overstressed.
'
2.3.5 Protection and Coordination
The inspectors reviewed a sampling of the overcurrent protection
device settings for various motor and load feeder breakers and the
settings of overcurrent devices for main supply breakers for 480
volt motor control center 3AB, 480 volt load center 3B and 4160
volt switchgear bus 3B. The settings of the overcurrent devices
applied with the 230 KV breakers were also reviewed. Documents
reviewed included relay setting sheets and time / current character-
istic plots taken from the protective relay setting calculations
E-90-0051, Rev. O, datad May 24, 1990, and E-90-0079, Rev. 1,
'
dated November 2, 1991.
Based on the information reviewed, the
inspectors concluded that adequate protection and protection
coordination was provided in the safety-related electrical distri-
bution system.
2.4
DC Systems
The designs of the Class 1E 250/125 VDC power systems were as-
sessed for adequacy. The inspectors reviewed documentation,
,
including diagrams, calculations, surveillance procedures and
licensing documents, which demonstrated system configuration,
system voltage conditions equipment loading, cable ampacity,
,
system protection and system protection coordination.
Based on
documentation reviewed and interviews with the licensee's
.
-
-
.
,
-
)
I
12
technical personnel, the inspectors concluded that these systems
were adequate in that they would have performed their intended
safety functions if required. However, findings were identified
by the inspectors which required further evaluation and corrective
,
'
actions. These are discussed in the following Sections 2.4.1,
2.4.2 and 2.4.3.
I
'
2.4.1
Battery Service Test
Section 4.8.2.3.2 of the licensee's Technical Specifications
stated, in part:
"Each 250/125 volt battery bank and charger
,
shall be demonstrated OPERABLE: ... d. At least once per la
'
months, during shutdown, by verifying that battery capacity is
,
adequate to supply and maintain in OPERABLE status all of the
actual emergency loads for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> when the battery is subjected
to a battery service test". The licensee's surveillance proce-
dure, SP-523, Rev. 28, dated February 25, 1993, Station Batteries
Service Test, was intended to provide the direction to comply with
this requirement. The inspectors noted that this procedure
indicated that a final terminal voltage of 105 volts for a battery
i
section serving a 125 volt (nominal) subsection was considered as
i
acceptable.
Section 3.2 of the procedure states, in part:
"The
terminal battery voltage will be used as the basis criteria for
acceptance. A final terminal voltage of 105 or greater will
ensure that the batteries will meet their design basis." Contrary
to this, the inspectors noted that the licensee's calculation
E-90-0100, Rev. 2, dated June 12, 1992, Electrical DC System
Revalidation, System Voltage Profile Calculation, indicated that
final terminal voltages of approximately 111 volts were required
to assure acceptable voltages at the emergency loads.
'
In response to the inspectors' concern, the licensee performed an
informal analysis, on or about July 22, 1993, using data from a
'
recent surveillance test (March, 1993) based on SP-523, Rev. 28,
and a less conservative load profile which more closely
represer,ted the actual loads.
(The profile currently used in
SP-523 is cased on loading that had existed prior to the installa-
tion of a non-Class 1E battery and the removal of the non-1E loads
from the Class 1E batteries in late 1991).
This analysis
indicated that minimum' battery terminal voltage would be approxi-
mately 112 volts with the reduced profile.
Based on this informal
analysis the inspectors concluded that the 250/125 volt Class IE
systems were operable. However, the inspectors considered the
licensee's lack of action to update the surveillance test
procedure, SP-523, based on information developed by calculation
E-90-0100 as a failure to comply with the design control require-
ments of 10 CFR 50, Appendix B, Criterion III. This noncompliance
is identified as Violation 302/93-18-01, Application of Voltage
Analysis Results to Battery yervice Test.
.
.,
.
-
.
1
,
-
13
,
,
!
2.4.2 Control Device Minimum Operating Voltages
The licensee's calculation E-90-0103, Rev.1, dated June 12, 1992,
indicated that terminal voltages available at many DC control
devices, during a two hour period in which battery charging of the
'
respective battery was assumed unavailable, could be 1c
than
the device manufacturers' published minimum values for r, .eration
j
or pick-up. Several of these devices were control relays associ-
{
ated with safety-related circuits and two devices were "close"
actuation coils for the output circuit breakers associated with
'
the two emergency diesel generators. The calculation showed that
,
l
available terminal voltages for the relays of concern ranged from
approximately 0.3 volts to 2.8 volts below the manufacturers'
published minimum pick-up value of 104 volts.
Further, the
'
calculation showed that available terminal voltages for the
,
emergency diesel generator circuit breaker "close" coils would be
'
approximately 16 volts below the published minimum pickup value of
90 volts.
In order to resolve these problems, the licensee tested
three to five "off-the-shelf" samples of the type of relays
i
involved and found that all operated with 70 volts applied to
!
their terminals. The two emergency diesel generator circuit
breakers, not samples or spares, were tested and shown to operate
'
when 70 volts was applied to their "close" coil terminals. Based
'
on this testing the licensee concluded that the devices had
sufficient terminal voltage for operation. Considering the small
voltage deficiency for the relays (0.3 to 2.8 volts) and that the
,
installed breaker coils had been shown to operate at a voltage
]
below the design requirement, the inspectors concluded that the
devices were presently operable. However, they questioned whether
the limited testing adequately demonstrated that devices would
continue to operate considering aging and other factors addressed
l
by manufacturers' qualification test programs. The inspectors
deferred complete acceptance of the test results and the
licensee's conclusions based thereon pending further NRC evalua-
i
tion. The NRC will evaluate criteria for use of tests to verify
device capabilities. Upon completion of this evaluation, Region
i
II will re-assess the licensee's use of testing to justify accept-
able device operation.
Pending completion of these actions this
3
matter is identified as Unresolved Item 302/93-18-03, Adequacy of
<
Testing Used to Demonstrate Devices Receive Sufficient Voltage. -A
i
similar concern regarding testing of devices for AC control
circuits, discussed in Section 2.3.3 of this report, will also be
addressed through this unresolved item.
4
2.4.3 Minimum Battery Electrolyte Temperature
i
!
During a review of the licensee's battery and charger calculation
E-90-0099, Rev. 2, dated June 9, 1992, the inspectors observed
that battery sizing had been based on a minimum electrolyte
temperature of 70 degrees F.
From a review of surveillance
j
records for a period of near record low temperatures (December
1989 - January 1990) the inspectors determined that electrolyte
i
l
,
-
.
-
. -
- . .
...
'
'
.
,
14
temperatures had dropped to about 67 degrees F.
Further, the
inspectors observed that, while the present Technical Specifica-
tions (TSs) did not specify a minimum battery temperature, pro-
posed new TSs (submitted to the NRC for approval) referred to a
minimum electrolyte temperature of 60 degrees F.
When questioned
by the inspectors, licensee personnel advised that the proposed TS
i
was in error and that as a result of a concern raised in their
internal audit (self-EDSFI) they had performed an informal calcu-
lation which indicated acceptable battery operation with an
electrolyte temperature as low as 64 degrees F.
The inspectors
verified the adequacy of the model and inputs used in this
informal computer calculation, as well as the result. The licens-
ee personnel advised that they would establish a lower electrolyte
temperature limit for use in the new TS reissue and would revise
)
calculation E-90-0099 at a later date.
Based on the results of
the informal calculation and their review of surveillance tempera-
l
ture records, the inspectors had no indication that the present
batterier would experience temperatures below the minimum required
'
by design.
However, the TS error described above was of concern
because the inspectors only examined two requirements in the
proposed new TSs and in both instances apparent errors were
discovered. The other example is described in Section 2.3.2
i
above. These TS errors appeared to indicate inadequate involve-
ment of the licensee's engineering in the development of the new
TSs. This matter is identified as Inspector Followup Item
302/93-18-05, Incorrect Values in Proposed New Technical Specifi-
cations. The inspectors informed the NRC TS reviewer of the
errors.
2.5
Containment Electrical Penetrations
The licensee's Problem Report, PR 93-0019, dated April 19, 1993,
" Electrical Penetrations", indicated that the electrical calcula-
tion enhancement program, when reviewing safety-related cable
ampacity, failed to analyze the electrical penetration conductors.
In response to this Problem Report, the licensee reviewed several
typical 480 V power circuit penetrations and determined they were
adequate. However, the inspectors observed that the 6900 V power
circuit penetrations associated with the Reactor Coolant Pumps,
which are the highest energy penetrations, had not been analyzed.
As a result of the inspectors' concern, licensee personnel
performed an analysis which demonstrated acceptable ampacity and
short-circuit withstand capability for the 6900 V penetrations.
The inspectors observed that PR 93-0019 identified a corrective
action to analyze all electrical penetration conductors by the end
of 1993. The inspectors identified the completion of electrical
penetration conductor analysis for subsequent review and verifica-
tion as Inspector Followup Item 302/93-18-06, Review of Ampacity
Analysis for Electric Penetration Conductors.
,
-
.
.,
'
.
.
15
3.0
MAINTENANCE, TESTING, CALIBRATION, AND CONFIGURATION CONTROL
,
i
The inspectors performed walkdown inspections of the EDS to assess The
material condition of the electrical equipment and panels.
Portions of
the "as installed" configuration of the EDS were examined to determine
its compliance with design drawings and documents.
Electrical mainte-
nance procedures, surveillances, and work requests were reviewed to
ensure the EDS was being properly maintained to perform its safety
'
functions. Data sheets from completed surveillance procedures were
reviewed to verify the EDS operated in accordance with design specifica-
'
tions and requirements. Actions being undertaken to assure adequate
fuse control were examined. Relay setting sheets, design drawings, and
completed calibration data sheets were reviewed to determine if an
effective program had been developed and implemented for controlling
i
setpoints for protective relays, overload relays, circuit breakers,
j
switchgear, and timing relays. The licensee's data base of preventive
j
,
maintenance was examined to determine if the equipment was being
inspected, tested, and serviced (if appropriate) on a regularly
scheduled basis. Actions to address failures of 4160-480 V ventilated
,
dry type transformers were evaluated.
'
'
3.1
Conclusions
'
The inspectors concluded that the currently maintained condition
of the EDS was adequate, except for the questionable condition of
,
the 4160-480 V Engineered Safeguards "B" train transformer.
)
Following failures of similar transformers in 1989/1990,the
'
subject transformer was scheduled for replacement. However, its
replacement had been incrementally delayed, apparently to avoid
impacting outage schedules. Other findings of lesser importance
1
were identified by the inspectors which require further evaluation
and appropriate corrective actions to ensure the future condition
of the EDS:
,
Several circuit breaker settings and sizes and a thermal
overload size differed from drawing requirements.
There was no scheduled periodic preventive maintenance for
inspections of 480 V MCCs and turbine building cable
attachments.
There was no periodic testing of molded case circuit
breakers.
.
The development and implementation of a fuse control program
~
was only about 20 percent completed and was not scheduled
'
for completion until 1996.
<
In contrast to the above concerns, the inspectors found evidence
the licensee had been undertaking many positive actions aimed at
maintaining or improving the condition of the EDS.
Positive
findings included the cleanliness and visibly good condition of
__
_ _ _ - _ _ _ _ _ _ _ _ _ . - _ _ - _ _ _ _ _ _ _ _ _
.
,
.
,
,
.
4
.
16
the equipment in the 120 VAC system, 125/250 VDC system, the 480 V
switchgear and 4.16 kV switchgear; new equipment that had been
recently added for either replacement or to supplement the EDS;
and the conformance of most installed equipment to the drawings.
3.2
Equipment Walkdown Inspections
The electrical components examined by the inspectors during
walkdown inspections included fuses, overload heaters, motor
contactors, protective relays, circuit breakers, switchgear,
batteries, chargers, inverters, cables, cable trays, transformers,
'
cubicles, and panels. The associated components, equipment, and
panels in the following electrical areas were inspected:
-
The safety-related 125/250 VDC system, batteries, chargers,
120 VAC inverters, and panels
-
The safety-related 480 V system, distribution load centers
and switchgear
-
The safety-related 4.16 kV system, switchgear, cubicles,
and panels
,
-
The 4.16 kV emergency diesel generators control panels
-
The 6.9 kV reactor auxiliary buses and switchgear
-
The 230/4.16 kV Offsite Power Transformer
-
The 230/4.16 kV Backup Engineered Safeguards Transformer
-
The 230 kV switchyard batteries, protective relays, and
control panels
-
The 500 kV switchyard batteries, protective relays, and
control panels
-
The protective relays for the 230 kV switchyard located in
Units 1 and 2 control room
-
The 125 VDC battery rooms in Units 1 and 2
-
All of the safety-related 480 V motor control centers
The walkdown inspections were conducted to determine the confor-
mance of installed equipment to design drawing requirements.
Design drawings used for the inspections were compared against the
"as installed" plant configuration. The material condition of the
EDS equipment and the housekeeping were also evaluated. The
inspectors examined all the cubicles in the seven different
safety-related MCCs.
1
1
j
.
.,
1
-
.
.
17
The drawings used for the inspection of the "as installed" condi-
tion of safety-related Class 1E MCCs included configuration
drawings and drawings that provided a compilation of engineering
data such as horsepower, full load current, locked rotor current,
motor starter size (contactor), thermal overload sizes, and
circuit breaker sizes and trip settings. This data was used by
the licensee to identify the specified components in each MCC
cubicle and for engineering studies and calculations.
From their inspections of MCCs, the inspectors identified MCC
breakers and breaker settings and a thermal overload device that
did not agree with the drawings:
MCC 3Al
In Cubicles IBR (RMP-A14), 7A (DHV-II), and 2C
(CFV-12) the circuit breaker trip settings were in the
"Hi" position instead of the "Lo" position specified
by Drawing EC-206-054, Rev. 22
MCC 3Al
In Cubicle 3DR (ACDP-116), a 40 ampere circuit breaker
was installed instead of the 30 ampere breaker
specified by Drawing EC-206-054, Rev. 22
l
MCC 3Al
In Cubicle 9A (CAV-126), the circuit breaker trip
'
setting was in the "2" position instead of the "Lo"
-
position specified by Drawing EC-205-055, Rev. 14
l
MCC 3A2
In Cubicle SAL (ACDP-5), a 70 ampere circuit breaker
4
l
was installed instead of the 80 ampere breaker
specified by Drawing EC-206-055, Rev.14
MCC 3AB
In Cubicle 2D (MUV-18), the circuit breaker trip
.
setting was set on the "2" position instead of the
"Lo" position specified by Drawing EC-206-058, Rev. 12
MCC 3B2
In Cubicle 6B (MUV-257), a N22 thermal overload was
installed instead of the N23 type specified by Drawing
EC-206-057, Rev. 11
MCC 3B2
In Cubicles 3D (AHF-17B) and 4C (AHF-18B), the circuit
breaker trip settings were in "F" position instead of
the "H" position specified by Drawing EC-206-057,
Rev. 11
The above listed noncompliances of installed equipment and set-
l
tings with drawings are identified as Violation 302/93-18-02,
Motor Control Center Breakers, Thermal Overload Device, and
Breaker Settings Not in Accordance with Drawings.
The licensee
initiated Problem Report 93-0176, dated July 16, 1993, to address
the corrective action for these noncompliances. Document Change
Notice 93-0214 was issued to correct Drawings EC-206-054, 055, and
057 and EC-208-005, Sheets AH-28 and AH-30.
The inspectors
verified correction of these drawings. The inspectors reviewed
.-
.
i
s
,
.
'
!
P
.
18
the completed work orders NU 0311920 and NU 0311922 to verify that
the breaker trip settings for MCCs 3Al and 3A2 were corrected.
Corrective action had not been completed for the breaker setting
in MCC 3AB Cubicle 20 and changing the 40 ampere breaker in MCC
3Al Cubicle 3DR.
Licensee personnel stated that these two items
i
could not be completed until the next refueling outage, although
1
work order WR 311922 had been initiated for MCC 3AB and modifica-
tion package MAR 93-07-03-01 for MCC 3A.
l
The inspectors conducted a walkdown of the 230/500 kV switchyards
including the relay block house to examine the switchyard battery,
,
the protective relays, the offsite 230/4.16 kV power transformer,
and other equipment to determine the general material condition.
i
The switchyard equipment was observed to be in good condition.
,
i
During the walkdown inspections of the safety-related 120 VAC
l
vital system, the 125/250 VDC system, the 480 V switchgear, the
!
4.16 kV switchgear, and the nonsafety-related reactor auxiliary
6.9 kV switchgear, the inspectors observed all of this equipment
,
to be in reasonably good condition and well maintained.
,
4
!
The inspectors concluded that the material condition of the EDS
equipment was satisfactorily maintained. Also, conformance of
installed configuration to drawing requirements appeared adequate
.
except for the breaker and thermal overload discrepancies
'
identified above. The inspectors determined that the breaker and
thermal overload discrepancies would not result in the inoperabil-
1
l
ity of any safety-related equipment. The inspectors were aware of
an open issue regarding cable separation, stemming from NRC
-
Violation 302/91-01-02, Adequacy of Cable Separation.
In the
!
specific hardware examined by the inspectors no cable separation
concerns were noted. However, this inspection did not address
!
cable separation extensively as it is to be evaluated in a
j
subsequent inspection.
!
3.3
Calibration
The inspectors examined the calibration program for the protective
i
relays and the timing relays used in the EDS, including those
installed in the 230 and 500 kV switchyards. Calibration proce-
'
dures PM-102, PM-102A, PM-102B, PM-102C, PM-102D, and PM-102E and
the relay setting sheets for the protective relays associated with
the safety-related portion of the EDS were reviewed. The
completed calibration data sheets for the protective relays in the -
.
230 kv switchyard, 4.16 kV engineered safeguard buses, Emergency
i
Diesel Generator (EDG) protection panels, and 480 V engineered
safeguards switchgear buses were reviewed and found complete, up
to date, and satisfactory.
In addition, the calibrations of the
solid state trip units in the metal clad breakers in the 480 V
!
load centers were found to be satisfactory.
!
i
-
- - - _ _ _ _ _ - .
~
.
.,
.
.
19
The licensee had upgraded the EDG load sequencers by replacing the
old electro-pneumatic timing relays with high accuracy solid state
rel ays. The inspectors reviewed the following modification
packages and surveillance procedure results to verify that the new
EDG sequencer load block timing relays had been functionally
tested and calibrated:
MAR 90-09-12-01, Install Higher Accuracy Time Delay Relays,
dated November 8, 1991.
MAR 88-05-24-01, DHP/EFP ES Start Modification, dated
,
May 13, 1990.
Completed Surveillance Procedure SP 137, Engineered Safe-
guards Actuation System Time Delay Relay Calibration, dated
April 13, 1993.
The inspectors concluded that the calibration program for the
protective relays and the sequencer timing relays was
satisfactory.
3.4
Preventive Maintenance for Electric Equipment
!
The inspectors questioned licensee personnel and reviewed the
licensee's database to establish the preventive maintenance
performed for various electrical equipment items. Also, they
reviewed preventive maintenance work orders and modifications to
'
determine 1f the preventive maintenance being performed was
7
adequate to maintain electrical equipment capable of performing
its safety function.
Three weaknesses in preventive maintenance were identified from
questioning licensee personnel. Two of the weaknesses are
identified as inspector followup items and the licensee is being
.
requested to provide a written response for these, giving their
4
plans and schedule for any corrective actions determined
necessary. The third weakness is to be addressed generically by
the NRC and no response is being requested at this time. The
weaknesses tre as follows:
The licensee had no preventive maintenance inspection to
l
determine the condition of the mechanical connections of the
230 and 500 kV power lines to the turbine building.
Failure
of the connections in high winds or a seismic event could
result in loss of preferred power to safety-related
equipment and could endanger plant personnel. This was
identified as Inspector Followup Item 302/93-18-07, lack of
Preventive Maintenance Inspection of Power Line Mechanical
Connections to the Turbine Building.
-
. _ _ _ _ _ _ _ _ _ _
-
.,
.
.
20
There was no scheduled periodic preventive mainteaance
inspection of the MCC motor starters, cubicle stab connec-
tions, bus bars, and panel bottoms to identify any build up
of dirt or dust or any deterioration that might be a fire
hazard or impair operation.
During walkdown inspections of
the safety-related MCCs the inspectors found the individual
cubicles in the MCCs were not dirty, though the bottoms of
-
the main panels had excessive dirt and dust. The lack of
scheduled periodic preventive maintenance inspections for
the MCCs was identified as Inspector Followup Item 302/93-
18-08, lack of Preventive Maintenance Inspection of Motor
Control Centers.
There was no periodic preventive maintenance trip setting
testing of molded case circuit breakers (HCCBs) to verify
their continued capabilities. The concern is that, in
aging, lubricant in the MCCBs may dry out or other degrada-
tion may occur and affect the trip calibration. Without
testing this degradation would not be detected. A failure
to test MCCBs has been identified as a weakness at other
plants and the need for generic action to address this is
being reviewed internally by the NRC.
It is anticipated
that any corrective action required as a result of the
internal NRC review will be applied generically to plants.
Therefore, the matter is not being identified for specific
followup at Crystal River.
Licensee personnel informed the
inspectors that a draft proposal for MCCB testing was being
reviewed by their management.
The inspectors reviewed work orders for the safety-related 480 V
switchgear load centers and breakers and the safety-related 4.16
kV switchgear buses and breakers.
In addition, portions of the
nonsafety-related 480 V switchgear, 4.15 kV switchgear, and the
6.9 kV switchgear preventive maintenance work orders were
reviewed. The work orders reviewed involved the following preven-
tive maintenance procedures:
PM-101, Preventive Maintenance For 4.16 kV And 6.9 kV Switc-
hgear Breakers
PM-106, Preventive Maintenance For Dry Transformers
PM-107, Preventive Maintenance For 480 V Switchgear Breakers
PM-119, Preventive Maintenance For Electrical Panels And
Cabinets
.
-
_
_ - _ _ _ _ _ _ _ _ _ .
-
.
.,
^
.
'
.
21
From their examination of the above work orders, the inspectors
verified that all the safety-related 480 V and 4.16 kV switchgear
circuit breakers and switchgear panels and buses were properly
serviced as required by the above procedures.
In addition, the
completed work orders reviewed for the nonsafety-related
switchgear indicated proper servicing.
,
The inspectors reviewed completed modification package MAR 90-05-
22-02, 480 V E.S. Breaker Changeout, dated November 7, 1991, which
was used to replace nine of the engineered safeguards 480 V
circuit breakers. They found that the documentation contained in
the package demonstrated adequate installation and post modifica-
tion testing.
The inspectors concluded that, except for the three weaknesses
identified above, the licensee had a satisfactory preventive
maintenance program. The lic'ensee is being requested to respond
'
to the followup items giving any corrective action plans and a
schedule for implementation.
3.5
Fuse Control
The inspectors were provided with a presentation and documentation
indicating that the licensee had initiated a fuse control program
which was approximately 20 percent complete. The program was not
scheduled for completion until 1996.
Licensee personnel explained
that the key element of the program was the listing of each fuse
and its specifications in the Computer Management Information
System (CHIS), allowing requirements for each fuse to be easily
accessed by computer. The inspectors observed data on the
computer (CHIS) for several fuses that had already been entered in
the system. The inspectors also examined the 20 percent of the
program that was completed. As an integral part of implementation
of the fuse control program, the licensee performed inspections to
identify the fuses currently installed and determined if they were
acceptable. The licensee had identified and resolved a number of
fuse discrepancies, none of which was found to result in inoperab-
ility of safety-related equipment.
The inspectors concluded that
the licensee will have a good fuse control program when it is
completed, but that the fuse discrepancies found by the lic.?nsee
,
indicate a weakness in past fuse control that still exists.
,
3.6
Transformer Failures
The CR3 electrical distribution system utilizes 4160-480 V venti-
lated dry type transformers to supply the 480 V and lower voltage
loads within the power plant. Two safety-related (Engineered
Safeguards) and six nonsafety-related transformers of various kVA
ratings are installed according to the original design. These
transformers are 150 degree C rise and have a Basic Impulse
Insulation Level rating of 60 kV.
The original set was supplied
by ITE Corporation, manufactured in 1971, and initially energized
_
- .
.
.
,
.
t
.
22
about 1975.
Due to three catastrophic failures that occurred in
the 1989/1990 time period, all but one of the eight have been
replaced with original spares or newly purchased units. The first
'
failure was in the safety-related train A unit. Approximately
'
eight months later two nonsafety-related units failed in the same
month. There were no failures before 1989.
Since the one trans-
former that has not been replaced is a safety-related transformer,
the inspectors reviewed the circumstances.
,
After the third failure occurred, some root cause analysis work
was done which took about five months. The root cause analysis
was somewhat inconclusive, and a decision was made to replace all
'
the transformers that had not already been replaced.
From their
review of the licensee's Failure Analysis 90-MTSW-3E-01, the
.
inspectors found that decision appeared to be based on the manufa-
cturer's verbal statement that the transformers had reached the
end of their useful life.
In November, 1990, the schedule for
replacement was developed and documented in Nonconforming Opera-
tions Report (NCOR)90-104. The schedule was to replace three
nonsafety-related transformers during the eighth mid-cycle outage
(MC8) and the remaining safety-related and nonsafety-related units
.
during the eighth refueling outage (RF8). MC8 took place in
October and November, 1991, and RF8 took place in May and June,
1992. The replacements were implemented according to schedule
except that the train B safety-related transformer was not
replaced, and had not yet been replaced at the time of this
inspection.
Given the circumstances described above, the inspectors were
concerned about the one safety-related transformer that has not
been replaced. The basis of the concern is that the three trans-
former failures out of eight installed in 1989/1990 provide
convincing evidence that this transformer is significantly less
'
reliable than originally assumed.
Failure of the transformer
could cause a plant trip and would result in the loss of AC power
to an entire train of safety-related equipment. The licensee did
not agree that failure to replace the transformer in question
perpetuated any safety hazard. They presented records indicating
that it had passed insulation power factor test, excitation
current test, ratio test, and winding and core insulation resis-
tance test; and had been inspected for dust and other signs of
deterioration in May, 1990, and March, 1993. The inspectors did
not agree that these tests and inspections guaranteed the
integrity of the transformer.
Documents included in the NCOR package indicated that the replace-
ment schedule established in November,1990, was established by
engineers without management involvement. Documents in the NCOR
also indicate that the schedule was questioned by management in
January, 1991, about nine months before MC8.
The reason given for
delaying replacement of the safety-related transformer beyond MC8
was that no work on train B had been scheduled, implying that to
.
!
.,
-
.
!
'
'
i
l
-
3
23
j
!
include this work would lengthen the outage. Apparently, this
!
reason held sway. The inspectors found that the safety-related B
)
transformer was not replaced in RF8 as originally scheduled.
'
J
They were informed that this was because the replacement trans-
former had a higher impedance than the originally installed
i
transformer and calculations completed in January,1992, indicated
!
that the replacement would result in devices receiving less than
rated voltage for certain design basis scenarios. The inspectors
did not view this as a valid reason because the voltage difference
'
involved was only 0.5 percent, only applied to very low
j
4
probability degraded voltage scenarios, and it was offset by the
,
j
risk involved in not replacing the problem transformer. Another
j
opportunity to replace the transformer was passed in MC9, which
~
took place in March,1993. The voltage problem reason no longer
-
i
existed because the 230-4.16 kV Backup Engineered Safeguards
)
Transformer was installed in MC9 which alleviated any voltage
'
i
problem. The inspectors concluded that the decision not to
replace the transformer was based on the consideration that to do
J
so might lengthen the outage. This issue is identified as
j
Inspector Followup Item 93-18-04, Increased Vulnerability Due to
Delay in Replacement of Potentially Degraded Engineered Safeguards
i
Transformer.
\\
4.0
INSPECTOR FOLLOWUP ITEM (92701) _
'
(Closed) Inspector Followup Item 302/92-18-01, Battery and Battery
Charger Issues.
This item was identified to: verify adequate correction of damage to the
"D" battery charger, following its failure of August 4, 1992; determine
whether work history indicated a pattern of repetitive charger failures;
i
and evaluate the licensee's actions to address apparent copper contami-
!
nation observed in newly installed 125/250 V batteries.
!
During the present inspection, the inspectors reviewed and verified the
completion of work orders NUO300279, NU300432, and NUO300435, which
,
restored the "D" battery charger to service. They also reviewed work
,
4
history and determined there was no repetitive pattern of failures.
'
j
Finally, they reviewed the licensee's actions to address the copper
contanination issue for the 125/250 V batteries and found.that the
-l
licensne had adequately addressed battery copper contamination as
,
follows:
Five cells had been contaminated.
The inspectors verified work
j
orders which replaced these cells (work orders NUO298022 and
I
i
0298247).
'
Investigation by the manufacturer determined that copper contami-
nation had occurred due to a manufacturing deficiency which
.
'
resulted in exposure of the copper core of battery cell posts to
.
the electrolyte. The electrochemical process in the battery cells
i
,
caused the copper to be dissolved from the posts and plated out on
.
1
)
i
~
.-
_
_
-
-
-
-
-.
-
---
-.
-.
_. .
.-
l
1
!
l
i
,
,
'
j
,
!
24
4
the cell plates. The inspectors reviewed the report of the
-
i
investigation, which was documented in a letter to the licensee
!
from the battery manufacturer (C&D Charter Power Systems) dated
l
March 8, 1993.
i
The inspectors verified that surveillance procedure SP-522 ,
j
Station Battery Inspection..., had been revised to give guidance
t
on inspections of batteries for copper contamination.
a
-
2
The inspectors concluded that the licensee has taken appropriate
corrective actions. This inspector followup item is closed.
,
,
5.0
EXIT INTERVIEW
i
l
The inspection scope and findings were. summarized on July 30, 1993, with
'
i
those persons indicated in Appendix B.
The lead inspector described the
.
areas inspected and discussed the inspection findings.
Dissenting
i
j
comments were not received from the licensee.
Proprietary information
j
is not contained in this report.
,
-
,
.
-
!
The substance of violations and other pertinent findings identified in
i
this inspection is described in the Executive Summary at the beginning
i
of this report.
!
J
l
i
'
?
4
!
1
i
!
)
i
- l
l
1
!~
1
l
,
2
--
, . - . -
- . .
., .
..-.
u
. - - - . . .
. . - . . . . . . . . . -
-
-
.~
_ _-
-
-
.
. - .
_ _ _ _ _ _ _ .
_ _ _ _ _ _ _ _ - _ - _ _
_
4
.,
,
- f
l
- i
'
25
i
APPENDIX A - ACRONYMS AND ABBREVIATIONS
Alternating Current
ANSI
American National Standards Institute
j
BEST
Backup Engineered Safeguards Transformer
CFR
Code of Federal Regulations
l
CMIS
Computer Management Information System
l
CR3
Crystal River Unit 3 -
,
CR4
Crystal River Unit 4
1
Direct Current
1
'
EDS
Electrical Distribution System
EDSFI
Electrical Distribution System Functional Inspection
Engineered Safeguards
F
Fahrenheit
i
Final Safety Analysis Report
kV
Kilovolt
i
kVA
Kilovolt Amperes
kW
Kilowatt
i
Modification Approval Record
l
MC8
Eighth Mid-Cycle Outage
1
MC9
Ninth Mid-Cycle Outage
Motor Control Center
i
Molded Case Circuit. Breaker
mVAR
Megavolt. Amperes Reactive
NCOR
Nonconforming Operations Report
,
National Electrical Manufacturers Association -
NRC
Nuclear Regulatory Commission
'
Reactor Coolant Pump
RF8
Eighth Refueling Outage
RF9
Ninth Refueling Outage
TS
Technical Specific: tion
Uninterruptible Power Supply
V
Volts
VAC
Volts Alternating Current
VDC
Volts Direct Current
I
I
i
-
,
,
,
,
._
.-
,
?..,
,
i
E
26
APPENDIX B - PERSONS CONTACTED
Licensee Employees
- J. Alberdi, Manager Nuclear Plant Operations
- S. Ballet, Supervisor, Site Nuclear Engineering Services
- D. Bates, Supervisor, Quality Systems
- G. Becker, Manager, Site Nuclear Engineering ServicM
G. Boldt, Vice President Nuclear Production
l
- R. Davis, Manager, Nuclear Plant Maintenance
- M. Fitzgerald, Supervisor, Nuclear Plant Systems Engineering
- A. Friend, Nuclear Principal Licensing Engineer
- E. Fraats, Manager, Nuclear Compliance
l
- F. Fusick, Manager, Design and Modifications
N. Garg, Principal Nuclear Electrical Engineer
,
- L. Kelly, Director, Nuclear Operations Training
)
- C. Kish, Nuclear Project Engineer
R. Marckese, Nuclear Project Engineer
'
- P. McKee, Director, Quality Programs
- R. McLaughlin, Nuclear Regulatory Specialist
- J. Mesada, Manager Nuclear Operations Engineering
- J. Neubauer, Nuclear Engineering Assistant
l
- S. Powell, Manager, Nuclear Electrical Shop
i
- M. Rahman, Principal Nuclear Electrical Engineer
- S. Robinson, Manager, Nuclear Quality Assessments
P. Rubio, Principal Nuclear Electrical Engineer
- D. Shook, Nuclear Staff Engineer
D. Stillwagon, Principal Transmission and Distribution Planning
Engineer
- J. Terry, Manager, Nuclear Plant Systems Engineering
- S. Ulm, Nuclear Engineering Supervisor
- R. Widell, Director, Nuclear Operations Site Support
NRC Empleyees
'
- P. Holmes-Ray, Senior Resident Inspector
- J. Jaudon, Deputy Director, Division of Reactor Safety, Region II
- K. Landis, Section Chief, Division of Reactor Projects, Region II
H. Silver, Project Manager, NRC Office of Nuclear Reactor Regulation
- Attended exit interview
l
l