ML18100A871
| ML18100A871 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/07/1994 |
| From: | HAGAN J J Public Service Enterprise Group |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLR-N94013, NUDOCS 9402170304 | |
| Download: ML18100A871 (14) | |
See also: IR 05000272/1993082
Text
Public Service Electric and Gas Company Joseph J. Hagan Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1200
Vice President
-Nuclear Operations
FEB 0 7 1994 NLR-N94013
United States Nuclear Regulatory
Commission
Document Control
Washington, DC 20555 Gentlemen:
RESPONSE TO UNRESOLVED
ITEMS FROM INSPECTION
REPORT 50-272/93-82
& 50-311/93-82
SALEM GENERATING
STATION UNITS NO. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 on December 7, 1993, Public Service Electric and Gas Company (PSE&G) received NRC Inspection.Report
Nos. 50-272/93:..82
and 50-311/93-82
for the Electrical
Distribution
System Functional
Inspection (EDSFI) conducted
from August 16 to September
3, 1993. As requested
by the NRC, the following
attachment
provides a schedule for resolution
of the 13 Unresolved
Items identified
in this report. If yo*u have any qliestions
regarding
this transmittal, please . do not hesitate to contact us. Attachment
(1) ' r.: f; :::, j ,J \.J *f L. 9402170304 ADOCK PDR
Document Control Desk NLR...,N94013
2 C Mr. T. T. Martin, Administrator
-Region I u. s. Nuclear Regulatory
Commission
475 Allendale
Road King of Prussia, PA 19406 Mr. J. c. Stone, Licensing
Project Manager U. s. Nuclear Regulatory
Commission
One White Flint North 11555 Rockville
Pike Rockville, MD 20852 Mr. c. Marschall (S09) USNRC Senior Resident Inspector
Mr. K. Tosch, Manager, IV NJ Department
of Environmental
Protection
Division of Environmental
Quality Bureau of Nuclear Engineering
CN 415 Trenton, NJ 08625 F£B 0 7 1994
Attachment
RESPONSE TO UNRESOLVED
ITEMS FROM INSPECTION
REPORT 50-272/93-82
& 50-311/93-82
SALEM GENERATING
STATION UNITS NO. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 Unresolved
Item 93-82-01 a) "The team noted that two transformers
of each channel were fed by the same breaker at the 4kV bus. These two transformers
would not be electrically
independent, and each of them is susceptible
to unnecessary
high switching
voltage surges generated
by the other transformer.
This voltage surge could exceed the Basic Insulation
Level (BIL) of these transformers
(25kV at the 4kV side and 10 kV at the low voltage side). There was no surge protection
on the 4kV vital busses, and no voltage surge study." b) "The licensee stated that there were four failures on the nonclass lE transformers
and one failure on the vital transformer
between 1990 and 1992. As a result of-an analysis, the licensee determined
that there was a lack of layer insulation
between the high voltage winding layers 3 and 4, and planned to replace both the vital and nonvital transformers
with higher BIL transformers." Response a) A previous study was performed
by Power Technology
Inc. which indicates
that the failure mode suspected (i.e., failure of one transformer
damaging the adjacent transformer)
is unlikely due to the fact that the. transformers
are connected
to the bus by
short cables. However, in the event that one of the two transformers
is lost, the respective
channel becomes inoperable.
Since Salem station only requires two out of three vital channels to shut down, the present design with the 4160/240 V and 4160/480 V transformers
for each vital bus fed by the same breaker is acceptable.
Also, each transformer
is provided with its own overcurrent
protection.
b) PSE&G plans to replace the type vital transformers
with higher BIL rating on the following
schedule:.
NLR-N94013
Transformer
2A, 2B, & 2C_* 4160/480 v -1 Outage Date 2R7 4/93 BIL Comments 60 kV complete_
- 25 kV BIL
Transformer
Outage Date BIL lA, lB, & lC lRll 10/93 60 kV complete*
4160/480 v 2A, 2B, & 2c 2R8 10/94 60 kV 4160/240 v lA, lB, & lC 1R12 3/95 60 kV 4160/240 v Unresolved
Item 93-82-02 "The team reviewed the loading demands O*f the EDG. under various postulated
design basis events. The worst EDG loading given in the licensee's
EDG loading calculation
was EDG 2A in case B, LOCA plus loss of offsite power (LOOP) scenario.
The.EOG loading for the first 20 minutes was about 2814 kW and followed by 2841 kW for the remaining
1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 40 minutes, with power factor about 0.88 lagging. This loading was just within the EOG 2-hour rating of 2860 kW; the team did not see any spare capacity for any future load increases.
The team noted the following
deficiencies
in the calculation:
a. the calculation
did not include all the intermittent
loads, e.g., motor-operated
valves (MOVs), which could be running during the first two hours following
a postulated
accidents;
b. the calculation
did not include all the small motor loads, which were controlled
by their process signals. These loads are: service water sump pumps (SWSP), EDG starting air compressors (EDG SAC), and RHR sump pumps (RHRSP); c. the load of the 115 Vac inverter, which supplies power to the instrument
buses, was assumed to be 110% of the walkdown readings of the inverters.
There was no basis to support that these figures were the worst case inverter loadings during the accident condition;
and d. the EDG load calculation
did not consider load -variation
due to voltage and frequency
variations." Response a&b) The assumption
used for the intermittent
loads is considered
to be accurate.
These process controlled
loads are not likely to run at the same time and therefore, the loading tables for the generators
should not .However, the fact that these loads are not NLR-N94013
2
- * c) d) locked off and that they are process controlled, there is a remote possibility
that they.could
all run simultaneously.
There. should be sufficient . margin within the 1/2 hour rating of the EDG to operate this equipment.
This margin is not required for the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or continuous
ratings of the EDGs because these loads are intermittent
type loads. The inverter loading is not a significant
issue with regard to the EDG loading because there was considerable
conservatism
in the calculation
with regard to the loads used for the battery chargers.
PSE&G plans to more accurately
reflect the battery charger loading in the EDG calculation
and apply the margin gained to the inverter loadings.
The margin gained should allow the inverters be loaded to their ratings in the EDG calculation.
The EDG calculation
is a steady state calculation.
This assumes that the average voltage and frequency
provided by the EDG will be the nominal values. While it is true that if the voltage regulator
and engine governor control voltage and frequency
at their respective
upper limits, the load on the EDG will increase.
This change in voltage and frequency
cannot be considered
the steady state or average condition.
There should be sufficient
margin within the 1/2 hour rating to accept this short term bounding operating
condition.
Therefore, this margin should not be required for the continuous
rating. PSE&G will revise the Emergency
Diesel Generator
loqd calculation (ES-9.002)
by August 31, 1994, to include analysis of the above concerns.
Unresolved
Item 93-82-03 "The team identified
that the current EDG surveillance
test procedure
and Unit 2 technical
specifications
allowed the EDG to operate at a steady state at as low as 90% voltage (3744V), which is lower than the degraded voltage setpoint.
The licensee agreed to revise the surveillance
test procedure
and request a change to the technical
specifications.
The team examined the past test results (S2.0P-ST.SSP-0003(Q)
for EDG 2B, and S2.0P-ST.SSP-0004-(Q)
for EOG 2C) and found the steady-state
voltage of the EDG had been consistently
maintained
above the 95% level, i.e.,. higher than
The Unit 1 technical
specifications
did not specify any limit on the EDG running voltage." NLR-N94013
3
Response PSE&G requested
a change to the technical
specifications
for Units 1 and 2 on September
30, 1993, to revise the minimum steady'state
voltage of the EDGs to be greater than or equal to395'0 volts, which is greater than the degraded voltage. setpoint.
The NRC approved this technical
specification
change as Amendment
Nos. 148 and 126 to the Salem Unit 1*and saiem Unit 2 Technical
Specifications, respectively, on November 30, 1993. Appropriate
surveillance
procedures
have been revised to *reflect this new minimum value for steady state EDG voltage. Unresolved
93-82-04 "In reviewing
the walkdown records enclosed in the EDG loading calculation, the team noticed that there were two 230V rated motors (Service Water Building Ventilation
fan lA and lC) at 248V and at 115% of the rated horse power. When the bus was at its.upper
limit.of 4500V, the terminal voltage of these two motors could be higher than 248V ,_. and the fan-motor
load could be even higher than 115% of rated HP. The licensee agreed to review the overvoltage
situation
and would include an over voltage evaluation
in the degraded vol_tage study. " Response The normal operating
voltage range of the vital .buses is maintained
between 4300 V to 4500 V (automatic
load tap changers are provided on the transformers
to keep the bus voltage in this range). If the bus voltage goes above * 4500 V, procedures
exist that direct the operators
to take actions to alleviate
this over voltage concern. This over * voltage condition
is not a significant
safety concern because the Unit 2 480 and 240 volt tran.sformers
are set in the nominal tap postiions.
This means that as long as the voltage is maintained
at the 4KV bus at less than 110%, the voltage at the 240 and 480 volt buses will also be less than 110%, precluding
any over voltage condition
for the control relays. PSE&G is in the process of implementing
a major power distribution
system modification.
Modification
of the Unit 1 power system is complete and Unit 2 will be completed
by end of the Eighth Refueling
outage which is currently
scheduled
for the fall of 1994. In the new configuration, the upper voltage limit will be controlled
at 4400 v. Calculations
have been performed
that prove that there are no over voltage conditions
in the new configuration-.
NLR-N94013
4
- * Unresolved
Item 93-82-05 "The team found the 4160V/480V
transformer
protection
was set at 300%. The protection
scheme would trip the transformer
supply breaker for current at 300% or higher (due to tolerance
of the relay). This protection
scheme did not fu*11y cover the full range of* the transformer
damage curve. The transformer
was not protect.ad
for. any overcurrent
below 300% of full.load
current. Furthermore, the operator had no means to know that the transformer
was overloaded
because there was no current measurement
at the 4160V side nor at the 480V side of the transformer, on the bus or in the control room. In case such a failure occurred, the fault wouid not be isolated in time. Eventually, this *fault would be isolated when it developed*into
a severe fauit with fault current higher than 300%. It was the team **s concern that transformer
overloading
could cause s*evere damage to or fire hazard in the 4160V switchgear
cubicle where the transformer
was located. The license agreed to evaluate this issue to determine
whether the 300% setting should be revised or other appropriate
corrective
actions should be taken." Response Design Change Packages (DCP) will be prepared by 3/31/94, to revise the setting of the transformer
overctirrent
relays to provide for optimal protection
of the tranformers.
These DCPs will be implemented
during the Twelfth Refueling
Outage for Unit 1 and the Eighth Refueling
Outage for Unit 2. Unresolved
Item 93-82-06 "The team reviewed the UPS purchase specification (No. 18310-E035A, dated November .4, 1988). Paragraph
3.6.3 of this document specified
that the total output voltage harmonic content should not exceed 5% of the fundamental
voltage. Nonlinear
load applied to the instrument
bus could affect the amount of harmonic distortion.
- The licensee stated that the total output voltage harmonic content was never verified after installation.
Recent inspections
by the NRC on other sites that had the same requirement
(5%) indicated
that this value exceeded 10% because of nonlinear
load applied to the output. The licensee agreed to verify this value: and, if the measured value exceeds the specified
value, evaluate the adverse effect on safety-related
instrumentation." Response PSE&G is in the process of developing
an acceptance
criteria for harmonic distortion
at the system level. This action includes obtaining
instrument
performance
data that is not NLR-N94013
5
readily available.
Based on the results of this activity, measurements
will be taken and corrective
actions will be implemented
as necessary
to ensure continued
reliable control/instrument
circuitry
operations.
A preliminary
assessment
of this* issue indicates
that.most
of the critical safety related instrumentation
at Salem utilizes DC power supplies fed from the vital AC system. It is our technical
opinion.that
this.design
feature would significantly
reduce the susceptibility
of the instrumentation
to effects associated
with harmonic distortion
of the AC source. In addition, PSE&G has reasonable
assurance
that adverse effects on saf
- instrumentation, if any,-are minimal due to no apparent trend or record of experienced
instrumentation
due to AC power quality related issues .. On the basis of _the above discussion, PSE&G will research industry data, and develop the harmonic distortion
acceptance
criteria by May 30, 1994. PSE&G will then take system measurements
and implement
corrective
actions as required.
The schedule for this activity will be aligned with the station operating
schedule.
unresolved
Item 93-82-08 (The NRC performed
a review of the EDG fuel oil storage tank curve and came to the following
conclusion.) "The tank volume curve calculations, S-C-YAR-CDC-095
Rev. 1, which provided conversion
of tank volume to height, failed t6 account for the unusable volume (vortex, -imperfection
of fabrication
and installation, etc,) and level instrument
error. Since this calculation
also applies to the other 28 tanks for both units, the licensee agreed to review the calculation
to* ensure that unusable volume and level instrument
error were considered
in obtaining
the total usable volume for those tanks." Response PSE&G has performed
a review of safety-related
tank internals
and has noted that anti-vortexing
baffles were installed
in most tanks to alleviate
the vortexing
effect. In the case of the Diesel Fuel Oil Storage Tank, where anti-vortexing
devices were noticeably
a:Qsent, PSE&G ha-s studied the vortexing
effect on* the fuel oil storage level and concluded
that it is minimal. PSE&G believes that the* identified
concern is a result of lack of consistent, documented
criteria for tank sizing. * NLR-N94013
6
PSE&G will formulate
a technical
standard for the sizing of all tanks and apply the standard criteria to prepare a minimum volume tank calculation
to clearly document the consideration
for all factors including
vortexing, level instrument.error, etc. PSE&G will also conduct a review of all Salem safety-related
tanks based on_ the above standard and will summarize
the results of the review in an engineering
evaluation.
PSE&G will complete this evaluation
by December of 1995, except for the Diesel Fuel Oil storage _Tank which will be completed
by June of 1994. PSE&G will also address level instrument
inaccuracies
on technical
specification
tanks *through the design basis reconsitution
effort on setpoints
that is currently
scheduled
for completion
by December of 1995. Unresolved
Item 9.3-82-10 "The team reviewed evaluations
S-l-CAV-MDC-0678
and S-2-CAV-MDC-0696 (Switchgear
and Penetration
Area Ventilation)
and concluded
that the equipment
in the switchgear
areas would be operable, considering
that the ambient temperatures
were expected to below the design ambient temperature
of 95°F in the coming months. The iicensee made a commitment
to complete the calculations, analytical/design
evaluation, etc. prior to the month of May 1994 (before the onset.of high sustained
outdoor temperatures)." Response PSE&G is in the process of calculating
the heat loads in the switchgear
room during normal and accident conditions.
Upon completion
of the heat load calculation, PSE&G will finalize the switchgear
room heatup calculations.
If the calculated
temperature
is qetermined
to be higher than 105°F (the maximum design temperature
for the switchgear
room) , .PSE&G will evaluate the effects of the increased
temperature
on the electrical
equipment
in the switchgear
area. PSE&G will complete these actions by 3/31/94. Unresolved
Item 93-82-11 "During the walkdown on August 16, 1993, the team observed that the nonsaf ety-related
MG sets were located in the area which houses all three 4kV vital buses. The team expressed
concern that MG set flywheel failure could disable two out of three 4kV vital buses. Two vital buses were required to achieve safe shutdown.
This licensee did not have
to address this concern. The licensee agreed to perform an evaluation/study
to address this issue." NLR-N94013
7
Response PSE&G issued engineering
evaluation
S-C-RCS-SEE-0866, "Rod Control System MG Set Flywheel Failure," on 1/12/94. This evaluation
concludes
that based on information
provided by Westinghouse
that the flywheels, which were designed, procured and fabricated
un'der closely controlled
quality standards, have such a high degree of structural
integrity
that the concern raised with respect to flywheel disintegration
is not credible.
The probability
of flywheel failure is sufficiently
small that the consequences
of failure need not be protected
against. Unresolved
Item 93-82-12 "The 18-month test procedure
for Unit 2 EDG specified
an EDG load equal to or greater than its 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> rating of 2860 kW for at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The team reviewed the test data of the 18-month (endurance)
tests of EDG 2A. The test data indicated
that the EDG was loaded consistently
between 2920 and 2950 kW for two hours in each test. This issue was discussed
with the licensee:
The licensee's
position on this issue was as follows. The temperature
and other variables
observed during these tests were well within the normal operating
range. The inspections, which took place 18 months after an endurance
test, did not reveal any unexpected
wear.to the diesel engine parts that would be expected to indicate wear. Additionally, the licensee contacted
the EDG vendor concerning
the consequences
of these tests. On October 27, 1993, the licensee called to inform the team that preliminary
analysis, by the vendor, of the test data indicated
no damage to the EDGs. The licensee was also considering
a revision of the technical
specification
requirements
and the test procedures
implementing
these requirements." Response PSE&G performed
an extensive
inspection
on 2C EDG during the Salem Unit 2 forced outage in December of 1993, to substantiate
a preliminary
analysis performed
by the EDG vendor that the past overloading
of the Unit 2 EDGs had no impact on EDG operability.
The 2C EDG was subjected
to the most severe overloading
during past surveillance
tests (the average 2 hr kW loading from the past three surveillance
tests for the 2C EDG was 2984 kW compared to EDG vendor's 2 hr rating of 2850 kW). The inspections
were assisted by a representative
of the EDG vendor. The inspection (conducted
under work order no. 931202257)
encompassed
sixty-six
(66) inspection
activities
covering more than 50% of the diesel power train [this is more than the manufacturer's
normal requirement
of 10% sampling inspection
of the power train following
a potential
overloading
NLR-N94013
8
situation].
The inspection
effort included both visual and magnetic-particle
testing (MT) of the following
components:
Cylinder heads (Inspected
& Hydrostatically
Tested) Pistons (Skirt and Crown) Piston Rings Wrist Pins Connecting
Rods Connecting
Rod Bearings Bearing Caps Rod Bolts The above inspection
indicated
satisfactory
results with no indication
of distress or abnormal wear. Additionally, 3R connecting
rod was checked for parallelism, bend/twist
in accordance
with manufacturer
It should be noted that the wrist pin is most sensitive
to the overloading
stress. The cylinder intake & exhaust valves, seat areas, and fire deck were all checked with.no sign of overheating
and erosion. The crankshaft
was visually inspected.
After diesel re-assembly, the EDG was re-tested
and the results were satisfactory.
Our analysis further indicates
that the maximum firing pressure during the overloading
stages was below 1950 psig. This is under the manufacturer's
ceiling pressure of 2100 psig, which is reco:m:fnended
in the Diesel Technical
Manual and was subsequently
discussed
with the diesel manufacturer.
With the results obtained above, PSE&G believes that the Unit 2 EDGs were not adversely
affected by past overloading
during surveillance
testing. PSE&G will summarize
our analysis in an engineering
evaluation
which will be completed
by June.30,
Unresolved
Item 93-82-13 "The team noted that many of the safety-related
molded case* circuit breakers (MCCB) were also used as isolation
devices, separating
safety-related
buses from nonsaf ety-related loads. If these MCCBs do not trip as required, a fault in the nonsaf ety-related
load may cause the feeder breaker to trip, thus losing the whole train, affecting
operation
of many safety-related
loads. Many of the safety-related
had not been current-tested
ever since they were installed
during the construction
stage more than 15 years ago. Recently, the NRC issued an Information
Notice (IN 93-64, "Periodic
Testing and Preventive
Maintenance
of MCCBs," issued August 12, 1993) discussing
MCCB failures during testing and addressing
the necessity
of periodic testing of MCCBs. The licensee agreed to evaluate the situation
at Salem to determine
their position regarding
periodic test programs of MCCBs. NLR-N94013
9
Response Presently, PSE&G is periodically
testing, per technical
specifications, all Molded Case Circuit Breakers (MCCB) protecting
containment
As a result of NRC Information
Notice 93-64, PSE&G is developing
a MCCB database for the installed
MCCBs, in particular
the MCCBs used for an isolation
device between vital and non-vital
equipment.
This database development
will be completed
by 4/29/94. PSE&G will
a determination
on testing program for MCCBs by 5/13/94. Unresolved
Item 93-82-15 "During review of past. surveillance
test,.as well as through direct observation
of the station .vital batteries, the team found that the lC and 2c, 125 Volt batteries
operate a temperature
range much greater than the other station batteries.
This is because these two batteries
are in separate enclosures
whe.re the environment
is not specifically
controlled.
From the surveillance
test results reviewed, the lC battery had an operating
range from 70°F to 96°F. The 2C battery had similar operating
temperatures.
The other station vital batteries
generally
remained within a three or four degree band from the nominal operating
temperature
of 77°F. * The licensee's
procedures
stated that the acceptable
operating
temperatures
for the batteries
are from 60°F to 105°F. While no unacceptable
condition
was *observed, the team was concerned
that the extreme temperatures
experienced
by these two batteries
may be leading to accelerated
aging. The licensee's
independent
EDSFI also reviewed this issue; however, there were no battery failures at that time. Therefore, .while the licensee's
assessment
noted the difference
in operating
temperatures
for the station batteries, no significant
finding was made and no
actions were deemed necessary.
Based 6n the failure of cell No. 47 and the operating
characteristics
of the lC battery, the team was concerned
that accelerated
aging may be occurring,
other actions by the licensee to ensure the continued
operability
of the battery. One indicator
of this was the build up of sediment in the jar bottoms for this cell, as well as for* five other cells in the same battery. The licensee stated that actions would be taken to identify the root cause of the failure of cell No. 47, especially
considering
the * effect of operating
temperatures
.... The long-term
corrective
actions for the lC and 2C, 125 volt batteries
remain unresolved
based on licensee assessment
of the aging effects due to the-operating
temperatures
experienced
by these components."*
NLR-N94013
10
Response Presently
lC & .2C batteries
operate in a non-air conditioned
room and are subject to ambient conditions
dictated by the weather. Temperatures
of the rooms vary depending
upon the outside temperatures.
Based on the review of quarterly
battery surveiliance
data for 1991, the highest and lowest temperatures
recorded in these rooms are 95°F and 65°F, respectively.
As a result, there is rio direct correlation
or quantification
between the length of time that _the batteries
will operate in a high temperature
scenario versus a low temperature
condition
and the effects on degrading
the batteries
versus increasing
their life. In accordance
with the battery manufacturer (C&D), the operation
of batteries
in an increased
temperature
will decrease the life expectancy
of the battery cells. .rt is generally
stated that for every l8°F above 77°F will decrease battery life by 50%. This battery manufacturer
also claims that lower than normal operating
temperatures
have the opposite effects on the batteries.
Therefore, at lower temperatures
the batteries
will last longer (at float voltages).
This implies that the varying battery room temperature
has some effect on battery life over an extended period of time, but does not create the possibility
of a sudden catastrophic
failure. The existing battery surveillance
program, at both Salem stations, adequately
monitors the battery status which will ensure that any degradation
of the battery life due to varying temperatures
will be detected before it leads to failure of the battery. Unresolved
Item 93-82-16 "In examining
the starting.
voltage and frequency
traces of the surveillance
test results on the Unit 2 EDGs, the team noted the frequency
fell below the 95% minimum value recommended
by Regulatory
Guide (RG) 1.9. However, the licensee did not fully commit to RG 1.9. The transient
voltage was above the 75% minimum value recommended
by RG 1.9. In addition, the licensee provided the team with copies of the EDG surveillance
test records on the Unit 2 EDGs. The team compared the above test results with the load demand kW and kvar profile during EDG sequencing, and estimated
that the EDG would be capable of picking up the Class lE loads as required.
The licensee agreed to perform the auto-sequencing
test of the Unit -1 EDGs in the *next refueling
outage surveillance
test to demqnstrate
that the transient
voltage and frequency
profiles are within the acceptable
limit." NLR-N94013
11
Response During lRll, Engineered
Safety Feature (ESF) Mode-Op tests were performed
in accordance
with procedures
Sl. OP-ST. SSP-0002 (Q) 11 1A Vital Bus, 11 Sl. OP-ST. SSP-0003 (Q) 11 1B Vital Bus, 11 and Sl.OP-ST.SSP-0004 (Q) "lC Vital Bus. 11 At no time did any Emergency
Diesel Generator (EDG) voltage fall below 75% (3120 VAC) of nominal generator
voltage when the largest single load (i.e., service water pump) as well as the other sequenced
loads were started. All EDG generator
voltages returned to 90% (3744 VAC) of nominal generator
voltage within 60% (2.4 seconds) of the largest load's load-sequence
time of 4 seconds. At no time did lA EDG or lB EDG frequency
fall below 95% (57 Hz) of nominal generator
frequency.
lC EDG frequency
dropped
57 Hz* and took more than 2.4 seconds to .recover, however, all lC EDG loads started and accelerated
to rated speed. Based on the above test results, Unit 1 EDGs' voltage and frequency
response met the intent of Regulatory
Guide 1.9. The fallowing
table is a summary of the above recor_der
chart test results. EOO/I.oad
Test Min. Freq Freq Resp:>nse*
Volt ResPC>nse*
1A Blackout 57.40 Hz 1.47 Sec 0.85 Sec 1A Target Load* 58.20 Hz 0.94 Sec 0.91 Sec 1B Blackout 57.30 Hz 1.62 Sec 1.16 Sec Target Load* 57.36 Hz 1.62 Sec 1.26 Sec lC Blackout 56.56 Hz 2.57 Sec 1.34 Sec lC Target Load* 58.16 Hz 1.05 Sec 1.38 Sec *Target Load is the load the generator
will see just prior to starting the largest load based on EDG Load Study * Calculation
The frequency
response is the time from when generator
frequency
decreased
below 58.8 Hz to when generator
frequency
recovered
above 58.8 Hz. The voltage response*
is the time from when generator
voltage decreased
below 3744 VAC to wnen generator
voltage recovered
above 3744 VAC. NLR-N94013
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