ML20249B570
| ML20249B570 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 06/18/1998 |
| From: | Pulley H UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-1042, NUDOCS 9806230316 | |
| Download: ML20249B570 (6) | |
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USEC A Global Energy Company I
June 18,1998 GDP 98-1042 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)
Docket No. 70-7001 Event Report ER-98-12 Pursuant to 10 CFR 76.120(d)(2), enclosed is the required 30-day written report for the loss of Criticality Accident Alarm System (C AAS) beacons at C-746-Q, due to a generator trip. This was initially reported on May 19,1998 (NRC No. 34263).
Commitments contained in this submittal are identified in Enclosure 2. Any questions regarding this matter should be directed to Larry Jackson at (502) 441-6796.
Sincerely, i
ow General Manager Paducah Gaseous Diffusion Plant I
Enclosures:
As Stated l
I cc:
NRC Region Ill Office NRC Resident Inspector-PGDP I /
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'P906230316 990618 5 PDR ADOCK 07007001 C
PDRS P.O. Box 1410, Paducan, KY 42001 Telephone 502-441-5803 Fax 502-441-5801 http://www.usec.com OtTices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC
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4 Docket No. 70-7001 GDP 98-1042 Page1of4 EVENT REPORT ER-98-12 DESCRIPTION OF EVENT On May 19,1998, at 0923 hrs., a portable generator which was providing temporary power to the C-746-Q criticality accident alarm system (CAAS) tripped during refueling operations. The loss of power was initially detected by the actuanon of a CAAS trouble alarm in C-300. The C-746-Q CAAS system was declared inoperable at 0925 hra, and actions associated with the Limiting Conditions for Operation (LCO) were initiated. Power Operations personnel restarted the portable generator at 0928 hrs, and the C-746-Q CAAS system was declared operable.
The tripping of the generator resulted in a loss of power for approximately five minutes to the CAAS beacons located on the outside of the C-746-Q building. CAAS detectability was not affected during the power outage, due to battery backup of the CAAS detectors. Likewise, the loss of power did not negatively impact the audible alarm capability of the C-746-Q CAAS system, since the motive force for the audible alarm consists of a dedicated nitrogen system which is triggered by a 24-volt solenoid, powered from the battery-backed CAAS cluster. Reference to the CAAS alarm lights appears in the Basis statement ofTechnical Safety Requirement 2.6.4.1. In accordance with 10 CFR 76.120(c)(2), the event was reported to the Nuclear Regulatory Commission (NRC) on May 19, 1998 (Reference NRC Notification Worksheet No. 34263).
The C-746-Q CAAS is fed from the Radiation Alarm Cabinet (RAC). This RAC is normally fed from Lighting Panel A, circuit No.12, but can also attemately be fed from a diesel generator. The generator connection modification was added in 1993, under Engineering Service Order (ESO) 17180. Cluster AC, Cluster AD, and four beacon lights outside C-746-Q are fed from the RAC.
This circuit experiences periodic outages, due to the need to deenergize the circuitry for maintenance activities. In this particular event, maintenance was being conducted on the B-2 street lighting circuit, which removed normal power from the CAAS. In response to these periodic outages, ESO Z99470 was issued on October 24,1997, to supply a more reliable source of power to the C-746-Q building. The ESO includes removing the C-746-Q power supply from the B-2 circuit and reconnecting it to the West Transformer 138. This work, when completed, will provide a more reliable source of power to the CAAS.
CAUSES OF EVENT A. Direct Cause The direct cause of the CAAS inoperability was the tripping of the diesel generator.
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Docket No. 70-7001 GDP 98-1042 Page 2 0f 4 B. Root Cause 1
The diesel generator (ONAN, Model 120DFAC-E, 230kVA), which is used for attemate
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connection to the RAC, is sensitive to tripping during refueling. Based on the historical
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operation of this diesel, as observed by Electrical Maintenance personnel, the diesel will trip due j
to overspeed if the fuel is fed in too fast. In this event, neither Power Operaticas personnel, who were responsible for the operation of the generator, nor Stores personnel, who were responsible for reflieling the generator, were aware of the vulnerability of the generator tripping during refueling. If the vulnerability had been mcognized, the issue of refueling while the generator was supplying power to the C-746-Q CAAS ceuld have been avoided in this event by simply
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ensuring the tank was full prior to operation of the generator. The root cause of the diesel generator trip is attnbuted to the failure to establish adequate administrative controls to ensure reliable operation of the generator during refueling operations.
Following the event, planned outages of the B-2 street lighting were discontinued until the issues involving this event were resolved (Corrective Actions Taken No. 2). Power Operations has completed corrective actions to prevent future unplanned outages of the CAAS at C-746.Q due to genemtor tripping during refueling operations. Electrical Maintenance and Power Operations personnel will be required to request the Plant Shift Superintendent (PSS) to enter the action steps of LCO 2.6.4.lb at C-746-Q when installing the generator, refueling the generator, or returning the power supply to normal at C-746-Q. Additionally, the diesel generator will be 1
refueled befom being placed in service at C-746-Q. These requirements have been documented
'l in Power Operations' instructions, " Installation of Generator at C-746-Q," (Corrective Actions Taken No. 4) and in a letter to Electrical Maintenance and Power Operations front-line managers (Corrective Actions Taken No. 5). Also, a precautionary sign has been installed on the ONAN diesel generator warning that refueling too fast will cause the operating generator to trip (Corrective Actions Taken No.3). Stores personnel responsible for fueling the generator at C-I 746-Q will complete a documented cmw briefing or required reading on this event report related to the fueling of the generator at C-746-Q. (Corrective Action Planned No.1)
The requirement to enter the actions steps of LCO 2.6.4.lb when installing refueling, or disconnecting the generator at C-746-Q and the requirement to refuel prior to pla _.g the C-746-l Q generator in service will also be documented in CP2-CO-CA2030, " Operation of the l
Criticality Accident Alarm System" (Corrective Action Planned Jo. 4). Additionally these requirements will be documented in a new Power Operations procedure covering the C-746-Q generator installation refueling, and disconnection (Corrective Actions Planned No. 3).
The frequency of using a generator for power to the C-746-Q CAAS will be greatly reduced upon completion and implementation of ESO Z99470, to reconfigure the source of normal power. (Corrective Actions Planned No. 2 and No. 5) l l
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i Docket No. 70-7001 GDP 98-1042 Page 3 of 4
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l CORRECTIVE ACTIONS A. Corrective Actions Taken j
- 1. On October 24,1997, ESO Z99470 was issued to reconfigure the CAAS source of electrical power.
- 2. On May 22,1998, planned outages of the B-2 street lighting circuit were discontinued until the issues surrounding the C-746-Q CAAS are resolved.
- 3. On June 9,1998, Power Operations installed a precautionary sign on the ONAN diesel generator, warning that refueling too fast will cause the operating generator to trip.
- 4. On June 9,1998, Power Operations modified the instructions for " Installation of Generator at C-746-Q" to request entering the action steps of LCO 2.6.4.1 b at C-746-Q when installing the generator, mfueling the generator, or returning the power supply to normal and to ensure the generator fuel tank is full prior to placing in service.-
- 5. On June 9,1998, Power Operations requested, in writing, that Electrical Maintenance and Power Operations front-line managers ensure the generator is refueled before placing in service at C-746-Q and request the PSS to enter the action steps of LCO 2.6.4.1b at C-746-Q f
when installing the generator, refueling the generator, or disconnecting the generator and j
returning to normal service, j
l B. Corrective Actions Planned j
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By July 10,1998, Stores will complete a documented crew briefing or required reading on this event report related to fueling the generator at C-746-Q for all Stores personnel who have responsibility to fuel the generator at C-746-Q.
- 2. By July 31,1998, Engineering will certify for construction the design for ESO Z99470 to supply a more reliable source of power to the C-746-Q building.
- 3. By October 30, *.998, Power Operations will issue either a Long Term Order or a procedure covering the C-746-Q ger.erator installation, refueling, and disconnection
- 4. By October 30,1998, Operctaons will revise and issue CP2-CO-CA2030," Operations of the
' Criticality Accident Alarm System," to require that the actions steps of LCO 2.6.4.lb will
Docket No. 70-7001.
1 GDP 98-1042 Page 4 of 4 be entered when installing, refueling, or disconnecting the generator supplying power to the C-746-Q CAAS and to ensure that the generator fuel tank is full prior to placing in service.
' 5. By February 27,1999, Operations will implement the design for ESO Z99470 to supply a
. more reliable source ofpower for the C-746-Q CAAS.
i EXTENT OF EXPOSURE OF INDIVIDUALS TO RADIATION OR TO RADIOACTIVE MATERIALS None.
LESSONS LEARNED l
Ensure adequate controls are in place when using a generator to supply alternate power to Q, AQ-
. NCS, and AQ systems to neduce the risk of unplanned power outages.
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.- _., e Docket No. 70-7001-GDP 98-1042 Page1of1 List ofCommitments Event Report ER-98-12 l'
- 11. By July 10,1998, Stores will complete a documented crew briefing or required reading on this event report related to fueling the generator at C-746-Q for all Stores personnel who have responsibility to fuel the generator at C-746-Q.
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By July 31,1998, Engineering will certify for construction the design for ESO Z99470 to supply a more reliable source ofpower to the C-746-Q building.
~ 3.J By October 30,1998, Power Operations will issue either a Long Term Order or a procedure covering the C-746-Q generator installation, refueling, and disconnection
- 4. By October 30,1998, Operations will revise and issue CP2-CO-CA2030," Operations of the
. Criticality Accident Alarm System," to require that the actions steps of LCO 2.6.4,1b will be entered lwhen installing, refueling, or disconnecting the generator su' plying power to the C-746-p Q CAAS and to ensure that the generator fuel tank is full prior to placing in service.
- 5. By February 27,1999, Operations will implement the design for ESO Z99470 to supply a more reliable source ofpower for the C-746-Q CAAS!
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