Part 21 Report - 1998-251
ACCESSION #: 9803040126
LICENSEE EVENT REPORT (LER)
FACILITY NAME: Clinton Power Station PAGE: 1 OF 5
DOCKET NUMBER: 05000461
TITLE: Incorrect Calculation in Diesel Generator Control
Circuitry Results in Insufficient Voltage and
Inoperability of the Division I Diesel Generator
EVENT DATE: 01/31/98 LER #: 98-006-00 REPORT DATE: 03/02/98
OTHER FACILITIES INVOLVED: None DOCKET NO: 05000
OPERATING MODE: 4 POWER LEVEL: 000
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR
SECTION:
50.73(a))(2)(ii)
OTHER
LICENSEE CONTACT FOR THIS LER:
NAME: M. G. McMenamin, Design Engineer TELEPHONE: (217) 935-8881,
Extension 3469
COMPONENT FAILURE DESCRIPTION:
CAUSE: SYSTEM: COMPONENT: MANUFACTURER:
REPORTABLE NPRDS:
SUPPLEMENTAL REPORT EXPECTED: NO
ABSTRACT:
With the plant in Mode 4 (COLD SHUTDOWN) and the sixth refueling outage
In progress, a discrepancy in a Direct current voltage calculation for
the Division I Diesel Generator control circuitry was discovered. The
calculation did not Include the existence of two cables that are run to
the Remote Shutdown Panel and their effect on the voltage drop to the
Diesel Generator control panel. Preliminary evaluation of the impact of
this error indicated that there has not been sufficient voltage to the
control panel for all of its connected equipment. The cause for this
event was due to an erroneous calculation provided by Sargent and Lundy
design engineers. The engineer failed to include the cable lengths from
and to the Remote Shutdown Panel in the voltage drop calculation for the
Diesel Generator control Panel. This error was overlooked in several
subsequent revisions. The corrective actions for this event are to
restore the Diesel Generator control panel voltage to an acceptable
level, to review other voltage calculations to ensure no other circuits
omitted cabling, to review the control circuits that pass through the
Remote Shutdown Panel and to brief engineering personnel on reasons
learned from this event. This issue is also reportable under 10CFR21.
END OF ABSTRACT
TEXT PAGE 2 OF 5
DESCRIPTION OF EVENT
On January 31, 1998, the plant was in Mode 4 (COLD SHUTDOWN) for the
sixth refueling outage (RF-6), and reactor (RCT] coolant temperature was
being maintained within a band of 95 to 115 degrees Fahrenheit (F) and
pressure was zero pounds per square inch. A review was being performed
by Nuclear Station Engineering Department personnel of the Emergency
Diesel Generator (EDG) [EK] control circuitry due to a supplier
deficiency noted with the air start solenoids [SOL]. During this review,
a discrepancy was identified with a calculation for the Direct Current
(DC) feed to the Division I DG control panel (1PL12JA) (PL). The
identified error was that certain cables [CBL3], which comprise part of
the normal DC feed to the Division I DG control panel, had not been
included in the voltage drop calculation to the panel. An informal
calculation of the resistances and voltage drop, with the additional
cable lengths included, indicated that the acceptance criteria of the
original calculation had not been met. Condition Report (CR) 1-98-01-452
was written to address this issue.
The control power feed to 1PL12JA has an alternate feed through the
Remote Shutdown Panel (RSP). This alternate feed is routed through a
transfer switch located on the RSP. On February 4, 1996, during the
review of the voltage requirements for 1PL12JA, it was noted that the
amperage specifications for the transfer switch an the RSP were not
adequate for the revised calculation. CR 1-98-02-060 was written to
address this inadequacy.
The normal 125 volts (V) DC power is supplied to panel 1PL12JA through a
feed cable (1DG01N) from the DC Motor Control Center (MCC). This cable
is a three conductor, 1/0 gauge utilizing two of the conductors to carry
the current to the panel. This cable choice appears to have treated the
voltage drop issue as the limiting factor for this circuit and, at the
time of installation, provided some margin in the design.
In order to provide the capability to transfer to an alternate source of
DC power, the normal feed circuit passes through the remote shutdown
panel. This was accomplished by the addition of cables to and from the
RSP, connecting through the transfer switch. This cabling (1DG01M and
1DG01P) consists of #6 American Wire Gauge (AWG) size conductors. This
part of the design failed to adequately evaluate the loads that existed
at the diesel panel versus the rating of the transfer switch contacts (20
Amps (A) continuous, 6.5A inductive interrupting). At the time of the
initial design, the maximum continuous load of the panel would have been
approximately 14A but the inductive load represented by two DG lube oil
motors [MO] would have been approximately 12.6A. The cable selection was
acceptable from an ampacity viewpoint but the voltage drop was not
considered. The original design current of 14A results in a voltage drop
that does not meet the criteria of Sargent and Lundy standards with
respect to motor feeds.
The resultant configuration should have been included as part of
calculation 19-D-28, "Review of Division I DC System 1A," (Revision 0
dated June 6, 1985). This calculation recognized that the DC lube oil
motors at the diesel would be running. In the "voltage drop in DC feeder
circuits" portion of calculation 19-D-28, the feeder circuit breaker to
1PL12JA was evaluated, but only with the three conductor 1/0 cable
(1DG01N) included and not the alternate feed through 1DG01M and 1DG01P.
Based on the calculation layout, the preparer of calculation 19-D-28 was
most likely working from the MCC key diagram and waxing
TEXT PAGE 3 OF 5
diagram as well as the cable database. These documents show 1DG01N
feeding 1PL12JA and terminating there. In order to identify the
additional cables involved, it would be necessary to go to the wiring
diagrams for the DG panel and the RSP, but there was nothing to
specifically lead the preparer to look at those documents.
After issuance of the initial calculation, it was unlikely that the error
would be subsequently identified since changes would tend to be loads and
this would only lead to revision of the numerical values and not
re-verification of the base data. This proved to be the case when the
diesel pre-lubrication modification (DG-08, Engineering Change Notice
6644, dated November 19, 1985) was issued. In revision three of the
calculation (issued February 18, 1987), the battery loading was revised
to reflect the two new DC motors at the diesel. However, the "voltage
drop in DC feeder circuit" was not revised. When this modification was
issued, the transfer switch at the RSP was not re-examined for the
additional load of two DC motors which took the continuous load to 26A,
which is greater than the switch rating of 20A.
In revision eight to calculation 19-D-28 (issued June 15, 1991), the
voltage drop portion was redone. This revision reformatted the
calculation and examined not only the voltage drop to 1PL12JA, but also
examined the addition of the two DC motors for pre-lubrication. However,
the revision failed to identify the cabling through the RSP and so the
acceptance values achieved were in fact not present at the motor
terminal. as a result of this error, the Division I DG control panel
would not have had sufficient voltage to operate all connected equipment
in the event of an actual lose of Alternating Current(AC) power start.
No automatic or manually initiated safety system responses were necessary
to place the plant in a safe and stable condition. This event was not
affected by other inoperable equipment or components.
CAUSE OF EVENT
There was an initial error in the preparation of calculation 19-D-28
provided by Sargent and Lundy, which was not detected in the initial
review nor subsequent revisions to the calculation. Thin error was
further aggravated by the improper selection of a transfer switch that
was marginal for its purpose and not further evaluated during later
design changes.
CORRECTIVE ACTION
The corrective actions for this event includes a resolution to the
voltage level required at the DC control panel. DC calculations for the
safety-related batteries will be reviewed to ensure no other circuits
emitted cabling. The control circuitry that runs through the RSP will
also be analyzed for other components to ensure proper voltage/amperage
is adequate for their operation. Engineering personnel will be briefed
on the lessons learned from this event.
TEXT PAGE 4 OF 5
ANALYSIS OF EVENT
This event is reportable under the provisions of 10CFR50.73(a)(2)(ii)(B)
due to the plant being in a condition outside of its design basis in that
there could have been insufficient voltage to the DG equipment fed by the
control panel such that they would not have performed their design
function.
An assessment of the safety consequences and implications of this event
concluded that this event was safety significant. In the event of a true
Loss of Alternating Current (AC) Power situation, the lack of sufficient
voltage could have had significant adverse affect to the operation of the
Division I DG up to and including failure of the diesel to start within
the required time period. This condition has existed since initial plant
licensing. This cabling configuration only effects the Division I Diesel
Generator. The DC feed to the Division II and III Diesel Generators do
not have the extra cabling that runs through the RSP.
ADDITIONAL INFORMATION
NO equipment or components failed during this event. Illinois Power has
not reported any events of insufficient DC voltage or underrated control
switches in the past two years.
For further information regarding this event, contact M. G. McMenamin,
Nuclear station Engineering, at (217) 935-8891, extension 3469
10CFR, PART 21 REPORT 21-98-014
On January 31, 1998, a review of the DC power to the control circuitry of
the DG control panel revealed that there was an error in the base
calculation for the required voltage to DC equipment associated with the
Division I DG. This error in preparing the calculation should be
reported under the provisions of 10CFR21. The basis for the reportable
conclusion is that the lack of sufficient voltage to the DG equipment
could have adverse effects to its operation when required.
(1) Walter G. MacFarland, IV, Chief Nuclear Officer of IP, Clinton
Power Station, Highway 54, 6 miles East, Clinton, Illinois,
61727, is informing the Nuclear Regulatory Commission of a
condition reportable under the provisions of 10CFR, Part 21.
(ii) The activity involved in this condition is the calculation
19-D-28, "Review of Division I DC System 1A," (Revision 0 dated
June 6, 1985).
(iii) This calculation was prepared and supplied by Sargent & Lundy.
(iv) The error in tho calculation was a failure to analyze the
cabling run from the DG control panel to the Remote Shutdown
Panel for its impact on the minimum required voltage required
for operation of the DC loads off of the DG control Panel.
Insufficient voltage to this equipment could result in failure
for the equipment to perform its desired function when required
by plant conditions.
TEXT PAGE 5 OF 5
(V) The error in this calculation was discovered an January 31,
1998, and determine to be potentially reportable under the
provisions of 10CFR21. The inadequacy of the transfer switch
was identified on February 4, 1998, and was determined to be
potentially reportable due to the error in the calculation
19-D-28.
(vi) The scope of the generic applicability of this issue at CPS has
not been determined. A review of DC calculations will be
performed and an analysis of other circuit configurations that
pass through the Remote Shutdown Panel will be performed.
(Vii) Corrective actions being taken by Illinois Power are discussed
in the corrective action section of the LER portion of this
report.
(Viii) IP has no advice for other purchasers or licensees regarding
this issue.
ATTACHMENT TO 9803040126 PAGE 1 OF 1
POWER REACTOR EVENT NUMBER: 33819
FACILITY: CLINTON REGION: 3 NOTIFICATION DATE: 03/02/98
UNIT: [1] [ ] [ ] STATE: IL NOTIFICATION TIME: 14:25
RX TYPE: [1] GE-6 EVENT DATE: 03/02/98
EVENT TIME: 14:25[CST]
NRC NOTIFIED BY: BYRON SHERMAN LAST UPDATE DATE: 03/02/98
HQ OPS OFFICER: JOHN MacKINNON
NOTIFICATIONS
EMERGENCY CLASS: NOT APPLICABLE
10 CFR SECTION:
CCCC 21.21 UNSPECIFIED PARAGRAPH
VERN HODGE (PCEB) NRR
UNIT SCRAM CODE RX CRIT INIT PWR INIT RX MODE
1 N N 0 COLD SHUTDOWN
CURR PWR CURR RX MODE
0 COLD SHUTDOWN
EVENT TEXT
INCORRECT CALCULATION IN DIESEL GENERATOR CONTROL CIRCUITRY
RESULTS IN
INSUFFICIENT VOLTAGE AND INOPERABILITY OF THE DIVISION 1 DIESEL
GENERATOR.
A DISCREPANCY IN A DIRECT CURRENT VOLTAGE CALCULATION FOR THE
DIVISION 1
DIESEL GENERATOR CONTROL CIRCUITRY WAS DISCOVERED. THE
CALCULATION DID
NOT INCLUDE THE EXISTENCE OF TWO CABLES THAT ARE RUN TO THE REMOTE
SHUTDOWN PANEL AND THEIR EFFECT ON THE VOLTAGE DROP TO THE DIESEL
GENERATOR CONTROL PANEL. PRELIMINARY EVALUATION OF THE IMPACT OF
THIS
ERROR INDICATED THAT THERE HAS NOT BEEN SUFFICIENT VOLTAGE TO THE
CONTROL
PANEL FOR ALL OF ITS CONNECTED EQUIPMENT. THE CAUSE FOR THIS EVENT
WAS
DUE TO AN ERRONEOUS CALCULATION PROVIDED BY SARGENT AND LUNDY
DESIGN
ENGINEERS. THE ENGINEER FAILED TO INCLUDE THE CABLE LENGTHS FROM
AND TO
THE REMOTE SHUTDOWN PANEL IN THE VOLTAGE DROP CALCULATION FOR THE
DIESEL
GENERATOR CONTROL PANEL. THIS ERROR WAS OVERLOOKED IN SEVERAL
SUBSEQUENT
REVISIONS. THE CORRECTIVE ACTIONS FOR THIS EVENT ARE TO RESTORE THE
DIESEL GENERATOR CONTROL PANEL VOLTAGE TO AN ACCEPTABLE LEVEL, TO
REVIEW
OTHER VOLTAGE CALCULATIONS TO ENSURE NO OTHER CIRCUITS OMITTED
CABLING,
TO REVIEW THE CONTROL CIRCUITS THAT PASS THROUGH THE REMOTE
SHUTDOWN
PANEL AND TO BRIEF ENGINEERING PERSONNEL ON LESSONS LEARNED FROM
THIS
EVENT. LER WAS SUBMITTED BY THE LICENSEE.
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