ML16154A825
| ML16154A825 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/08/1995 |
| From: | Steven Rudisail, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16154A826 | List: |
| References | |
| 50-269-95-16, 50-270-95-16, 50-287-95-16, NUDOCS 9508220219 | |
| Download: ML16154A825 (13) | |
See also: IR 05000269/1995016
Text
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REGUo
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
o
101 MARIETTA STREET, N.W., SUITE 2900
ATLANTA, GEORGIA 30323-0199
0A
Report Nos.:
50-269/95-16, 50-270/95-16 and 50-287/95-16
Licensee: Duke Power Company
422 South Church Street
Charlotte, NC
28242
Docket Nos.:
50-269, 50-270, and 50-287
License Nos.:
and DPR-55
Facility Name:
Oconee Nuclear Station Units 1, 2 and 3
Inspection Conducted:
July 10 - 14, 1995
Inspector:
/o
-73
c '
S.'Rudisail
Date Signed
Accompanying Personnel:
Virgil Beaston, NRR
Approved by:
M. B. Shymlock, Chief
Date Signed
Plant Systems Section
Engineering Branch
Division of Reactor Safety
SUMMARY
Scope:
This routine, announced inspection was conducted in the areas of electrical
design to review the licensee action in response to Electrical Distribution
System Functional Inspection (EDSFI) findings and other EDSFI issues
identified in NRC Inspection Report 50-269, 270, 287/93-02. These items were
being resolved as part of the licensee's Power Upgrade Project (PUP).
Other
items completed as part of the PUP effort were also reviewed.
Results:
In the areas inspected, violations or deviations were not identified.
The inspectors reviewed various PUP items completed in response to EDSFI
findings. These EDSFI findings were identified as Inspector Follow-up Item
(IFI) 93-02-03.
OThe inspectors reviewed calculations, calculations revisions, procedures and
design basis documentation which had been completed to address the EDSFI
findings.
Enclosure
9508220219 950811
PDR ADOCK 05000269
G
2
Overall, the calculations were of good quality with no problems identified
during the calculation reviews. The licensee corrective actions for these
items were technically sound and thorough.
In some cases, actions completed by the licensee substantiated the licensee
previous conclusion that systems as designed were adequate. However, in some
cases actions completed by the licensee in response to the EDSFI findings
resulted in additional analysis and corrective actions to be completed by the
licensee.
The inspectors reopened IFI 93-02-04 to document continuing staff evaluation
of six EDSFI inspection items. This item was reopened as IFI 95-16-01.
REPORT DETAILS
1.
Persons Contacted
Licensee Employees
- L. Azzarello, Mechanical Systems Engineering
M. Bailey, Regulatory Compliance
- E. Burchfield, Regulatory Compliance Manager
- D. Coyle, Mechanical Systems Engineering
J. Davis, Engineering
T. Grant, Electrical Systems Engineering
- T. Ledford, Electrical Systems Engineering
- C. Little, Electrical Systems Engineering
- J. Peele, Plant Manager
- L. Underwood, Electrical Systems Engineering
- L Wilkie, Safety Review Manager
Other licensee employee contacted during this inspection included
craftsmen, engineers, technicians, and administrative personnel.
NRC Employees:
- P. Harmon, Senior Resident Inspector
L. Keller, Resident Inspector
- Attended exit interview
Acronyms and abbreviations used throughout this report are identified in
the last paragraph.
2.
Background
During January 25 through March 5, 1993, the NRC conducted the
Electrical System Distribution Functional Inspection (EDSFI).
The
purpose of this inspection was to assess the capability of the Oconee
Electrical Distribution System to perform it functions during normal
operations and accident conditions. The conclusion of the EDSFI team
was that the electrical distribution system would perform its intended
function pending further analysis and testing by the licensee. During
the EDSFI inspection a violation and several deviations were identified.
Additionally, findings identified during the EDSFI were collectively
identified as IFI 93-02-03. Licensee actions.to address these findings
and NRC review of these actions are discussed within this report and in
previous inspection reports 50-269, 270, 287/94-26 and 50-269, 270,
287/95-10.
3.
Review of Inspector Follow-up Items (IP 92903, TI 2515/111)
The inspector reviewed the items identified at Oconee as Findings.
IFI 93-02-03, EDSFI Findings consisted of six findings with several
issues identified in each finding. This finding was closed in NRC
inspection report 50-269, 270, 287/94-26 to document the findings which
II
2
were closed in that report. IFI 94-26-02 was opened to identify the
EDSFI finding items which remain opened.
3.1
The inspectors reviewed PUP item 4.b which addressed EDSFI finding 2.g.
Finding 2.g of the Oconee EDSFI report recommended that the licensee
"Identify the full scope [of electrical components supplied by the
Keowee station batteries] and complete individual voltage component
calculations for Keowee".
Section 3.2.4.4 of the EDSFI report stated that the inspectors reviewed
calculation KC-0076, Rev. 2, Keowee 125 VDC Auxiliary Power System
Battery Voltage and Duty Cycle Calculation, and noted that there was no
discussion in the calculation which addressed the voltage limitations of
electrical equipment being supplied by the batteries. The adequacy of
voltage being supplied to some of the Keowee electrical components
(i.e.; the Keowee generators' field windings and field flashing
breakers) was to be addressed in other calculations being developed at
the time of the EDSFI inspection. The EDSFI inspectors stated in
section 3.2.4.4 that "The comprehensiveness of the scope of the
supplemental calculations to examine voltage adequacy at the component
level should be considered."
The inspectors reviewed calculation/analysis KC-Unit 1-2-0093, Keowee
125 Volt DC Voltage Adequacy Calculation, dated May 18, 1995. The
purpose of this calculation was to determine that under the worst case
load profile for the 125 volt dc Keowee power system, all devices
required to operated during an emergency start would have adequate
voltage. The worst case configuration analyzed by the licensee was a
Keowee Unit 2 black start (first minute load profile) with the unit 2
electrical equipment being supplied by the unit 1 battery through a
cross connect. The unit 1 battery was assumed to have 59 cells
available and to be supplying both its equipment and the unit 2
distribution center through the cross connect. This analysis was
performed to bound the case where one of the Keowee batteries is out of
service. It was assumed that the voltage drop to unit 2 loads was
limiting due to longer cable runs associated with unit 2 equipment.
This calculation identified that the voltage supplied to the Keowee Unit
2 governor actuator cabinet would only be marginally acceptable during
the worst case load profile analyzed and with the unit 1 battery near
the end of its life (80% capacity). In particular, the 99SN solenoid
was identified as the most limiting electrical component. The minimum
volt.age calculated for the 99SN solenoid was 77.8 volts dc. The minimum
test voltage shown to be acceptable for the solenoid to operated was 76
volts dc. While the minimum calculated voltage available to operate the
solenoid was above the minimum tested value, the licensee recognized
that a system improvement could be made to increase the voltage margin.
An additional calculation performed by the licensee showed that by
replacing the 400 feet of cable running from bus 2DA to 2LC1 with a more
direct cable of approximately 25 feet, the minimum calculated voltage
3
available to the solenoid would increase from 77.8 volts dc to 84.1
volts dc. The licensee is tracking this recommendation with PIP 0-095
0590, and plans to implement it at a future date.
The inspectors found the licensee's analysis acceptable which concluded
all devices powered by the Keowee 125 volt dc system and required to
operate during an emergency start would have adequate voltage. The
inspectors had no further concerns as a result of reviewing this
calculation. This item is closed.
3.2
The inspectors reviewed PUP item 4.e which addressed EDSFI item 2.b.
Finding 2.b of the Oconee EDSFI report stated "The team noted that there
was no analysis nor test to verify that the -rapid transfer (transfer of
power to MFBs) timing was correct."
Section 2.5, "Bus Transfer," of the EDSFI report stated "The team noted
there was no design limits nor verification of the residual voltage on
the bus, and the phase angles between the outgoing and incoming voltages
prior to the transfer."
The inspectors reviewed calculation/analysis OSC-5749, "6.9 and 4.16 kV
Auxiliary System Transfer Analysis," dated May 24, 1995. The purpose of
this calculation was to verify that excessive voltages would not be
applied to motors during the fast and slow bus transfers of the Oconee
auxiliary systems. This analysis was performed by the licensee using
CYME computer analysis software. The results of this computer analysis
were evaluated by the licensee using the 1.33 p.u. volts/hertz criteria
contained in ANSI Standard C50.41-1992.
This analysis identified two instances in which the 1.33 p.u.
volts/hertz criteria would not be meet. The first instance was a fast
transfer of the 4.16 kV bus during a unit shutdown. To correct this
finding, the licensee's staff has proposed that the fast bus transfer be
blocked during unit shutdowns when the plant's auxiliaries are being fed
from the unit auxiliary transformer. The second instance was a slow
transfer of the 6.9 kV bus during normal unit operations. In this case,
the licensee's staff has proposed that the minimum bus deadtime be
extended, or the slow transfer scheme be modified to included relays
which would monitor the residual bus voltage and supervise the slow
transfer. The implementation of these recommendations was being tracked
by PIP 0-095-0585.
The inspectors found the licensee's analysis acceptable, and did not
identify any additional concerns. Because the volts/hertz values for
the two instances identified by the licensee where a bus transfer could
exceed the ANSI C50.41-1992 recommended value of 1.33 p.u. volts/hertz
only exceeded that recommended value by a small amount (approximately
5-10%) and because these two transfers were not expected to occur
repeatedly prior to the licensee taking corrective actions, the
inspectors agreed with the licensee's conclusion that these findings did
not pose a significant safety concern. This item is closed.
4
3.3
The inspectors reviewed PUP item 4.g which addressed EDSFI item 2.c.
Finding 2.c of the Oconee EDSFI report stated "The licensee did not have
a transient voltage study for the 4 kV safety load groups when they are
supplied from the Lee gas turbine or from Central substation."
Section 2.6.1 of the EDSFI report states "during starting of a unit LOCA
loads, or starting of two unit shutdown loads, the transient voltage dip
could exceed 20% [when supplied from CT-5].
The licensee agreed to
prepare a transient voltage study on the 4 kV safety load groups when
they are supplied from Lee gas turbine or from Central substation."
The inspectors reviewed calculation/analysis OSC-3290, "Voltage Study
for Oconee Auxiliary Power Systems When Fed From Lee Combustion Turbine
Via CT5 Transformer," dated May 30, 1995. The purpose of this
calculation was to validate the licensee's CYME computer modeling of the
Lee combustion turbines supplying auxiliary power to Oconee and to
simulate Oconee LOCA/LOOP and LOOP loading when supplied from Lee
combustion turbines.
The licensee performed a series of four tests designed to evaluate the
CYME modeling of the Lee combustion turbines and the electrical circuit
that connects Lee combustion turbines to Oconee nuclear units. These
tests were: (1) start of supercharger fan SC [associated with Lee
combustion turbine 5C] from Lee combustion turbine 6C; .(2) start of
supercharger fan SC from the grid; (3) start of an ASW pump at Oconee
from Lee combustion turbine 6C; and (4) trip supercharger fan 6C when
supplied from Lee combustion turbine 6C while isolated from the grid.
The CYME simulation results showed good agreement with the field data
collected during the four tests listed above.
The results of calculation/analysis OSC-3290 showed that while bus
voltage could momentarily drop below 50% for a worst case loading
scenario voltage would recover quickly, and all motor loads would start
without actuation of protective relaying. The analysis conducted by the
licensee identified three recommendations that would improve system
performance during periods when Oconee auxiliaries were being fed from
Lee. These recommended improvements are listed below and were being
tracked by PIP 0-095-0616 for further consideration by the licensee:
(1) When LOCA and LOCA/LOOP loads are automatically loaded onto a Lee
unit, the speed droops 2 to 3 percent. Before 4.16 kV manual
loads are loaded onto Lee following a LOOP or LOCA/LOOP, the
Oconee operator should make sure that the frequency of the Lee
unit is restored to normal;
(2) Field tests performed to verify the CYME program indicates that
the reactive droop compensator on the voltage regulator is set
between 5 and 6 percent. A setting of 0% or close to 0% would
improve the Lee unit voltage response when the Oconee auxiliary
loads are connected to Lee; and
5
(3) The calculation results indicate that all motors would start and
that motor protective devices would not trip, however, 4 kV motor
protection settings should be reviewed and set closer to the motor
thermal damage curves (where possible) so that more of the motor
thermal capacity can be used during motor starts. Motors
specifically mentioned in the calculation were LPSW and LPI pump
motors.
The inspectors found the licensee's analysis adequate, and they agreed
with the licensee's conclusion that Lee combustion turbines could supply
adequate power to meet postulated Oconee LOOP or LOCA/LOOP accident
scenarios. The inspectors did not identify any further concerns while
reviewing this calculation. The adequacy of power supplied to Oconee
from Central substation was addressed in Inspection Report 95-10.
This
item is closed.
3.4
The inspectors reviewed the licensee actions completed in response to
EDSFI finding 6.a.
Finding 6.a of the EDSFI report stated "The team identified several
components involved in the operation of the Keowee units during an
emergency start which were not being tested."
Section 3.4.2.4 of the EDSFI report identified that testing procedures
associated with ACBs 1, 2, 3, and 4 were noted to have weaknesses.
Procedure MP/O/A/2001/2:
Inspection and Maintenance of Keowee ACBs and
Associated Disconnects and Bus did not provide sufficient detail for
testing the check valves on the air accumulator in each breaker.
The licensee had revised maintenance procedure MP/O/A/2001/2:
Inspection and Maintenance of Keowee ACBs and Associated Disconnects and
Bus to include specific instructions for checking the operation of these
check valves. The inspector reviewed the revised procedure and found
the instructions adequate for resolution of the EDSFI concern. This
item was closed.
3.5
The inspectors reviewed PUP item 18 which addressed EDSFI item 6.b.
Finding 6.b of the Oconee EDSFI report stated "Testing was not being
performed on safety related mechanical components (i.e.; coolers and
pumps)."
Section 3.4.2.4 of the EDSFI report stated "It was noted that
performance monitoring testing was not routinely performed on the safety
related mechanical components (coolers and pumps) at Keowee . . . During
the inspection, the team identified several valves which were required
to change position for Keowee to provide emergency power, which were not
included on the Keowee active valve list (KC-0085)." Valves 1 and 2 OG
7 (the Keowee governor oil tank float valves) were specifically
mentioned in
the report.
6
The function of valves l and 2 OG-7 is to close on low oil level in the
governor oil tank and prohibit air entrainment into the Keowee governor.
Should air displace oil in a governor, control of that unit's wicket
gates could be adversely affected. In a worst case scenario, the wicket
gates of the affected Keowee unit could be driven closed at such a rapid
rate that an excessive pressure surge would be created in the penstock,
potentially damaging the penstock which is common to both Keowee units.
At the time of the inspection, testing of these two valves was required
to be performed annually as a part of the governor actuator inspection
and maintenance procedures (MP/l/A/2200/003 and MP/2/A/2200/003).
Acceptable operation of valves 1 and 2 OG-7 had been verified on
February 20, 1995, and February 15, 1995, respectively. The inspectors
had no further concerns regarding the testing of these two valves.
The licensee had initiated PIP 0-094-1162 to track EDSFI item 6.b which
had a tentative completion date of November 1, 1995. Corrective actions
stated in the PIP required the inclusion of appropriate Keowee equipment
into the licensee's inservice testing program, development of inspection
and test procedures, and performance of any necessary modifications and
initial testing. Since the licensee has not completed its corrective
actions to finding 6.b, this item will remain open until the licensee
completes these actions, and they have been reviewed. This item is
open.
3.7
Item 3.b identified that a controlled document for the setpoints at
Keowee (except for electrical relay settings) was not available. This
item was addressed by the licensee as PUP item 1h.
The licensee
developed setpoint document changes which added all Keowee
instrumentation that have adjustable setpoints to the Oconee Alarm and
Setpoint Document. The inspector reviewed these setpoint document
changes and compared the setpoint values and process descriptions to
Keowee drawings, DBDs, annunciator response procedures, and equipment
settings in the field. With only a few exceptions the information was
correct and consistent between the various sources. For the
discrepancies identified, the licensee appropriately dispositioned the
items through their Problem Identification Process (PIP).
This item was
closed.
Item 3.c identified that bulletins, information notices and generic
letters had not been reviewed for applicability to Keowee. The licensee
subsequently performed a comprehensive search of their Licensing
Correspondence files and their Integrated Commitment Index in order to
identify the population of items that might be applicable to Keowee. The
licensee identified a total of 502 items for review. These items were
distributed to Engineering mechanical, electrical, and civil groups for
review of applicability to Keowee. If the item was found to be
applicable, then a review of Oconee's response was performed. If the
Oconee response included Keowee or if the actions taken covered Keowee,
then no further corrective action was taken.
Items that were found to
be applicable to Keowee, and no action for Keowee had been taken, were
then reviewed for appropriate corrective action. The inspector found
the approach taken by the licensee to identify all potential items
7
applicable to Keowee to be acceptable. The inspector performed a spot
check of several bulletins and generic letters and determined that they
were dispositioned correctly in regard to Keowee. This item was closed.
4.
Review of Power Upgrade Project Items not Identified as EDSFI Findings
(IP 92903)
4.1
The inspectors reviewed PUP item 66 which related to a preliminary
initial scope document that identified the need for a modification of
the Keowee voltage regulators.
The Keowee generators are designed to operate as the onsite emergency
power sources for the Oconee Nuclear Power Plants. As such, they must
be able to act as isolated power sources and maintain adequate output
voltage during a postulated accident scenario. Maintaining adequate
output voltage is the function of the Keowee voltage regulators. During
an emergency start of the Keowee units, the voltage regulators are
placed in automatic control.
Between the dates of September 9, 1992, and May 8, 1993, the Keowee
Units 1 & 2 voltage regulators failed a total of six times to transfer
to automatic control following normal automatic starts as documented by
PIPs 92-0455, 92-0490, 92-0647, 92-0718, 93-0340, and 93-0385. The
cause for these failures was not know at the time, but it was thought to
be due to an unreliable voltage adjuster (70V) cam switch. As a result
of these repeated failures, on May 8, 1993, a condition of operability
was placed on the Keowee units. This condition required operators to
verify that the S8 contacts on both the base adjuster (70B) and the
voltage adjuster (70V) of a Keowee voltage regulator closed following a
unit shutdown. Since the root cause of the voltage regulators to
transfer to automatic upon startup was believed to be due to misposition
of the voltage adjuster following a unit shutdown, this condition of
operability was implemented to ensure the Keowee units would by ready
for any subsequent emergency starts. To remove this condition of
operability and to improve the reliability of the Keowee units, the
licensee started development of modification package NSM ON-52965 to
upgrade the Keowee voltage regulators.
Subsequent to the implementation of the condition of operability on the
Keowee units, the failure of the voltage regulator to transfer to
automatic did not reoccur until April 20, 1995. At this time the
failure persisted. With the ability to repeat the failure to assist in
troubleshooting, the licensee was able to identify the root cause of the
problem. The problem was identified as a bad module in the voltage
regulator's synchronizer which caused the voltage adjuster (70V) to be
driven out of its preset position before the regulator could transfer to
automatic. A document review by the licensee showed that the on
December 23, 1992, the synchronizer from Unit 1 was replaced with the
one from unit 2. This finding was consistent with the fact that the
failures on unit 2 occurred prior to that date, and the failures on unit
1 occurred after that date.
8
Since the root cause of the failures had been identified and it was not
due to an unreliable voltage adjuster, the licensee removed the
condition of operability originally placed on the Keowee units. The
initial reason for the voltage regulator modification had been to remove
this condition of operability. Since the voltage regulator problem has
been identified and corrected, implementation of NSM ON-52965 is not
considered necessary for closer of this item. The licensee still
planned however to implement the modification. Also planned as a part
of NSM ON-52965 was the replacement of Keowee components identified as
seismically suspect and implementation of recommendations made by the
licensee's Keowee lockout relay study (KC-0107). This item is closed.
4.2
The inspectors reviewed PUP item 91 which evaluated the effect of a
momentary loss of voltage on one of the 120 volt ac vital I&C busses
caused by the current limiting feature of an inverter.
The inspectors reviewed section 13.1.2, 7.5 kVA Safety-Related Inverter
Output Fault, of calculation OSC-3120, Oconee Relay Settings and Breaker
Coordination, dated June 1, 1995. If a fault occurred on a load
connected to the 120 volt ac vital I&C busses, the inverter could go
into a current limit condition before the load breaker connecting the
1fault
tripped and cleared the fault. If this were to occur, the output
voltage of the inverter would be degraded and could be low enough to
prevent operation of some of the supplied loads. Loads that would be of
concern in this situation are the Reactor Protection System (RPS) and
Inadequate Core Cooling Monitor (ICCM) instrument channels.
There are four RPS channels (2-out-of-4 logic) supplied from four
different inverters and two ICCM channels supplied from two of these
inverters which provide inputs to the Diverse Scram System (DSS)(2-out
of-2 logic) of ATWS. Two of the four inverters, therefore, supply both
one channel of RPS and one channel of ICCM. The licensee's analysis
documented that a momentary loss of voltage to one of these loads (RPS
or ICCM) would not be a problem for RPS because RPS has three other
redundant channels and would still be capable of performing its safety
function. The safety function of DSS is to provide backup for RPS in
the event of a common-mode failure of all channels of RPS. Since a
fault in a single channel of RPS is not a common-mode failure of RPS,
RPS would still be capable of performing its safety function, and
operation of the ICCM channel effected by the momentary loss of voltage
would not be required. The licenses analysis also concluded that any
postulated fault would be cleared by a load breaker prior to tripping
the inverter or the 125 volt dc panelboard supplying the inverter. The
inspectors had no concerns with the licensee's analysis. This item is
closed.
4.3
The inspectors reviewed PUP items 75 and 78. These items identified
licensee action to review Design Basis Documentation (DBD) against test
procedures and calculations to ensure that the ability to meet the
design basis was either tested or demonstrated with calculations.
9
The inspectors selected a sample of electrical DBDs to review the
methodology taken by the licensee for this review. The following DBDs
were reviewed:
(1) 120 VAC Instrumentation and Control Power
(2) 125 VDC SSF Auxiliary Power
(3) 230 kV Switchyard 125 VDC Power System
(4) 230 kV Switchyard
(5) 4 kV Essential Auxiliary Power System
(6) 4160/600/120V SSF Essential Power System
(7) Keowee Emergency Power
(8) Lee Emergency Power System
(9) Keowee 125 VDC Power System
(10) 250 VDC Auxilary Power System
The inspector reviewed the testing and calculations identified in the
DBD Testing/Calculation Matrix for each DBD. The design basis
requirements were identified with the relevant calculation and/or test
procedures to document the testing or calculation which demonstrated the
ability of the system to meet the design basis requirements.
The inspector considered the methodology for cross referencing the
testing and calculation to the design basis requirement as adequate.
The inspector did not review the test procedures for adequacy of scope
or procedural content.
4.4
The inspector reviewed PUP item 85. This item was identified as a PUP
item to resolve a problem with the Keowee 125 VDC breaker settings and
drawing discrepancies.
The licensee identified that various Keowee 125
VDC Distribution Center load breaker types were different than those
shown on one-line diagrams and vendor drawings. Additionally, breaker
coordination analysis has revealed that coordination could be
significantly improved by increasing battery breaker and tie-breaker
instantaneous settings to the HI setting.
The inspectors reviewed the licensee actions taken for this PUP item.
Minor modification OE-8047 was being implemented to revise drawings and
change breaker settings to address the identified discrepancies. The
actions were being tracked under PIP NO. 0-094-1655 and 2-093-0438. The
inspectors reviewed the scope of the corrective actions identified in
the PIPs and the minor modification. The actions were adequate to
address the concerns. This item was closed.
5.
Review of Inspector Followup Item 93-02-04:
EDSFI Items identified for
further NRC Review
IFI 93-02-04 identified various items during the EDSFI for additional
NRC review. This IFI was closed in NRC inspection report (IR)
50-269,
270, 287/94-26. This item was closed because no corrective actions were
required by the licensee. However, NRC review of these items was not
complete. The specific items below will be addressed as additional NRC
reviews are completed. Therefore, this item is reopened as IFI 95-16-01
Followup EDSFI Open Issues.
10
Item 1:
(page 25) The SSF make-up pump is rated at 29 gpm. TS 3.1.6.9
allows leakage not exceeding 30 gpm.
Item 2:
(page 12)
The MFBMP logic is designated as non-safety related.
The licensee basis for this designation is (1) during a LOOP only DBE
there is no established time period necessary for automatic power
restoration and (2) during a LOCA the EPSL would automatically restore
power to the bus.
Item 3:
(page 15) The feeder cables for the switchyard battery
chargers are non-safety related and the chargers are load shed during a
LOOP. TS requires the battery chargers be operable for the switchyard
batteries to be operable. The licensee considers the battery chargers
to be safety related. The basis for designating the feeder cables as
non-safety related is that manual action in the switchyard could be
taken to operate switchyard breakers if the switchyard batteries are
unavailable.
Item 4: (page 23)
The licensee does not analyze smart failures within
control systems when analyzing for single failure. This item was
identified in regard to the voltage regulator but captured a broader
issue applying to Oconee implementation of single failure.
(Finding
5.a is related)
Item 5:
(page 25) The definition of single failure and how it is
applied in reference to the 230 kV switchyard was questioned. The team
identified that the licensee did not consider a failure concurrent with
the initiating event in their single failure analysis in regard to the
230 kV switchyard as detailed in the FSAR. The licensee considers part
of the switchyard to be on-site even though the UFSAR analyzes part of
the off-site system. The team considered it to be off-site until
isolated by the switchyard logic and that a single failure should be
considered with the initiating LOCA/LOOP.
Item 6:
(page 22)
The team questioned the licensee's conformance to
the single failure criteria as stated in the UFSAR. Section 8.3.1.2 of
the UFSAR states " The basic design criteria of the entire emergency
power system of a nuclear unit, including the generating sources,
distribution equipment, and controls is that a single failure of any
component, passive or active, will not preclude the system from
supplying emergency power when required. The team found the licensee
had not fully analyzed the controls consistent with this requirement
specifically in regard to the governor control systems.
(Finding 4.a
and 5.a are related.)
6.
Exit Meeting
The inspection scope and results were summarized on July 14, 1995, with
those individuals indicated in paragraph 1. The inspector described the
areas inspected and discussed in detail the inspection findings. There
was no dissenting comments received from the licensee. Proprietary
information is not contained in this report.
11
Items opened/closed in this report Inspection Report IFI 95-16-01,
Followup of Open EDSFI Issues (IFI 93-02-04).
7.
Acronyms and Abbreviations
CFR
Code of Federal Regulations
EDSFI
Electrical Distribution System Functional Inspection
Final Safety Analysis Report
IFI
Inspector Follow-up Item
IP
Inspection Procedure
IR
Inspection Report
kA
Kiloamperes
kV
Kilovolts
KVA
Kilo- Volt- Amperes
Loss of Coolant Accident
Motor Control Center
MVA
Mega Volt Amperes
NRC
Nuclear Regulatory Commission
Nuclear Reactor Regulation
Mega-Watts
Problem Investigation Process
PUP
Power Upgrade Project
SSF
Safe Shutdown Facility
TI
Temporary Instruction
V
Volts
VAC
Volts Alternating Current
VDC
Volts Direct Current
VPC
Volts Per Cell