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. *** END OF DOCUMENT ***

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