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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