United States Nuclear Regulatory Commission - Protecting People and the Environment


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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