Part 21 Report - 1998-111

 
 

ACCESSION #:  9801260201

                       LICENSEE EVENT REPORT (LER)



FACILITY NAME:  Clinton Power Station                     PAGE: 1 OF 4



DOCKET NUMBER:  05000461



TITLE:  Failure of Cooling Unit Manufacturer to Install Motor

        Shaft Key Leads to Inoperability of Shutdown Service

        Water Pump Room Cooling Unit



EVENT DATE:  12/22/97   LER #:  97-036-00   REPORT DATE:  01/19/98



OTHER FACILITIES INVOLVED:                          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:  S. P. O'Riley, Engineer, Nuclear Station

                 Engineering Department     TELEPHONE:  (217) 935-8881,

                                                   Extension 3491



COMPONENT FAILURE DESCRIPTION:

CAUSE:      SYSTEM:       COMPONENT:       MANUFACTURER:

REPORTABLE NPRDS:



SUPPLEMENTAL REPORT EXPECTED:  NO



ABSTRACT:



On December 22, 1997, Engineering completed an evaluation of a missing

motor shaft key that connects the motor to the fan hub of the Division II

shutdown service water pump room cooler.  This evaluation determined that

without the motor shaft key the Division II shutdown service water pump

room cooler could not be considered operable.  The inoperability of the

room cooler causes the associated Division II shutdown service water pump

to be inoperable.  It is likely that the motor shaft key was not

installed during initial manufacturing by Buffalo Forge.  Corrective

action for this event is to install the required motor shaft key.  A

review of the maintenance history at Clinton Power Station for similar

fans manufactured by Buffalo Forge revealed that similar conditions with

Buffalo Forge supplied cooling fans have not been previously identified.

This event is reportable under 10 CFR Part 21.



END OF ABSTRACT



TEXT                                                          PAGE 2 OF 4



DESCRIPTION OF EVENT



On December 19, 1997, maintenance technicians were performing an

inspection of 1VH01CB, Division II shutdown service water [BI) pump [P]

room cooling fan [FAN] motor [MO].  This fan is required to be operable

to ensure that the shutdown service water pump room is maintained below

122 degrees Fahrenheit during pump operation.  Without proper operation

of this cooling fan, the shutdown service water pump cannot be expected

to perform its function under all environmental conditions.  Therefore

when this fan is inoperable the shutdown service water system is

inoperable.  During this inspection the technicians identified that the

key that connects the motor shaft to the fan hub was missing from the

keyway.  Condition report 1-97-12-301 was initiated to evaluate and

investigate the cause of this condition.



On December 22, 1997, the plant was in Mode 4 (Cold Shutdown) for the

sixth refueling outage (RF-6), reactor [RCT] coolant temperature was

being maintained within a band of 95 to 115 degrees Fahrenheit and

pressure was atmospheric.  Engineering completed an evaluation of the

Division II shutdown service water pump room cooling fan's operability

with the key not installed.  This evaluation identified that the motor

shaft normally transfers the rotational energy to the fan hub through a

shear connection via the metal key between the motor shaft and fan hub.

Inspection of the aluminum fan hub showed that it was galled with pieces

of aluminum protruding into the keyway.  Inspection of the motor shaft

disclosed that aluminum had deposited uniformly on it along the entire

area of engagement.  The fan was able to rotate and move air without the

normally installed key being present.  The engineering evaluation

concluded that it could not be determined with confidence that the

Division II shutdown service water pump room cooling fan would operate

without the key installed at the required air flow for thirty days as

required by the design basis of the fan.  Therefore, the fan was

considered inoperable for the entire time the key was not installed.



Investigation into the maintenance history of the fan revealed that no

maintenance that would have required the removal of the shaft key had

been conducted since initial installation of the fan.  The room cooling

unit is manufactured and shipped as a complete unit.  Assembly of the fan

onto the motor shaft is not required upon delivery of the unit.  This led

the evaluator to conclude that the shaft key was not installed when the

cooling fan unit was manufactured by Buffalo Forge.  However,

preoperational test results showed that the unit met the design flow

requirements when the unit was initially installed.



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 THE EVENT



Illinois Power believes that it is likely that the motor shaft key was

not installed during manufacture of the unit by Buffalo Forge because no

past maintenance work was identified that would have required the removal

and reinstallation of the motor shaft key.



TEXT                                                          PAGE 3 OF 4



CORRECTIVE ACTION



The cooling fan was restored to an operable status by completing

installation of the motor shaft key to fan hub connection.  Twenty-two

safety-related vane axial fans similar to 1VH01CB were purchased by

Illinois Power for Clinton Power Station.  Thirteen of these fans have

had maintenance activities performed on them previously which should have

identified if the motor shaft key was not installed.  Also, a review of

previous condition reports did not reveal any additional instances of a

motor shaft key missing on these twenty-two similar safety-related vane

axial fans.  The corresponding Division I shutdown service water room

cooling unit is included in the thirteen safety-related fans that have

already been inspected.  No additional inspection of other similar vane

axial fans is warranted.



ANALYSIS OF EVENT



This event is reportable under the provisions of 10CFR50.73 (a)(2)(ii)(B)

as a condition that resulted in the nuclear power plant being in a

condition outside its design basis.  The missing motor shaft key

connecting the motor to the fan created a condition where the shutdown

service water pump room cooling fan may not have been able to perform its

design function.  The Division II shutdown service water pump room cooler

is assumed to keep the shutdown service water pump room at or below the

design basis room temperature of 122 degrees Fahrenheit.  Because of the

potential inability of the cooler to keep the shutdown service water pump

room at or below 122 degrees Fahrenheit, the associated shutdown service

water pump can not be considered operable with the room cooler

inoperable.  Illinois Power believes that this condition has existed

since initial installation of the shutdown service water room cooling

unit at Clinton Power Station.



This event is potentially nuclear safety significant.  The engineering

evaluation associated with the missing shaft key on the shutdown service

water pump room cooling fan determined that it was not Possible to

provide assurance that the fan would provide the required air flow for

thirty days without the installation of the motor shaft key.  If the

shutdown service water pump room cooling fan is unable to deliver the

required air flow through the room cooler for the required thirty day

duration it is possible, depending on local environmental conditions,

that the temperature in the room could exceed its design basis value.  If

this temperature is exceeded satisfactory operation of the associated

Division II shutdown service water pump, as required by plant design

basis, could not be assured.  The Division I and Division III shutdown

service water pumps were not affected by this event.



ADDITIONAL INFORMATION



No equipment or components failed during this event.



Illinois Power has not reported in recent history an event involving a

missing shaft key on safety related ventilation fans.



For further information on this event contact Steve O'Riley, Engineer,

Nuclear Station Engineering Department, at (217) 935-8881, extension

3491.



TEXT                                                          PAGE 4 OF 4



10CFR Part 21 Report 21-98-002



On January 6, 1998, Illinois Power determined that Buffalo Forge most

likely failed to install the motor shaft key on the Division II shutdown

service water pump room cooler during the manufacturing process.  This

issue was determined to be potentially reportable under 10 CFR Part 21.

Illinois Power has completed evaluation of this issue and concludes that

it is reportable under the provisions of 10 CFR Part 21.



Illinois Power is providing the following information in accordance with

10 CFR Part 21.21(d)(4).  Initial notification of this matter will be

provided by facsimile of this letter to the NRC Operations Center in

accordance with 10 CFR Part 21.21(d)(3) within 2 days of the date the

responsible officer approves this report.



(i)       Walter G. MacFarland, IV, Chief Nuclear Officer of Illinois

          Power Company, Clinton Power Station, Highway 54, 6 miles East,

          Clinton, Illinois, 61727, is informing the NRC of a condition

          reportable under the provisions of 10 CFR Part 21 by means of

          this report.



(ii)      The basic component involved in this report is the failure to

          install the shutdown cooling water pump room cooling fan motor

          shaft key for the Division II shutdown service water pump room

          cooler fan.



(iii)     The shutdown service water pump room cooler was supplied by

          Buffalo Forge.



(iv)      As discussed in the DESCRIPTION OF EVENT portion of this report

          the nature of the condition is the failure to install a motor

          shaft key on the Division II shutdown service water pump room

          cooler.



          As discussed in the ANALYSIS OF EVENT portion of this report,

          failure to install the motor shaft key on the Division II

          shutdown service water pump room cooler could allow the

          temperature in the pump room to exceed the design basis

          temperature required for the operation of the Division II

          shutdown service water pump.



(v)       On January 6, 1998, Illinois Power identified that the Division

          II shutdown service water pump room cooling fan missing motor

          shaft key may have been caused by the failure of the

          manufacturer to install it when the unit was assembled at the

          factory and Illinois Power determined that this issue was

          potentially reportable under 10 CFR Part 21.



(vi)      This issue affects the Division II shutdown service water pump

          room cooler.



(vii)     The corrective action that Illinois Power is taking for this

          event is discussed in the CORRECTIVE ACTION portion of this

          report.



(viii)    Illinois Power has no additional information to offer.



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