ML20249B072
| ML20249B072 | |
| Person / Time | |
|---|---|
| Site: | Paducah Gaseous Diffusion Plant |
| Issue date: | 06/17/1998 |
| From: | Pulley H UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-1045, NUDOCS 9806220038 | |
| Download: ML20249B072 (3) | |
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USEC A Global Energy Company j
June 17,1998 GDP 98-1045 United States Nuclear Regulatory Commission Attention: Document Control Desk Washingion, DC 20555-0001 Paducah Gaseous Diffusion Plant (PGDP)
Docket No. 70-7001 Event Report ER-98-14 Pursuant to 10CFR76.120 (c)(2), enclosed is the required 30-day written event report covering the partial failure of the plant air system when an air corepressor in Building C-335 failed to compress.
The Nuclear Regulatory Commission (NRC) was notified of the event on May 22,1998, at 1008 hrs.
- (NRC No. 34277), Enclosure 2 is a list of commitments made in this report.
Any questions regarding this matter should be directed to Larry Jackson at (502) 441-6796.
Sincerely, l!
iokd Pull General Menager i
Paducah Gasenus Diffusion Plant
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Enclosures:
As Stated
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cc: NRC Region III Office NRC Resident Inspector - PGDP i
9806220038 980617 PDR ADOCK 07007001 C
PDR PO. Box 1410, Paducah, KY 42001 Telephone 502-441-5803 Fax 502-441-5801 http://www.usec.com OfIices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC a-_________ _ _ _
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p Docket No. 70-7001 GDP 98-1045 Page 1 of 2 EVENT REPORT ER-98-14 DESCRIPTION OF EVENI.
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On May 21,1998, at approximately 1624 hrs., a partial failure of the plant air system occurred when i
an Ingersoll-Rand Centac centrifugal compressor in Building C-335 unloaded and did not compress.
1The partial loss of the plant air system caused the Criticality Accident Alarm System (CAAS) to be
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declared inoperable, due to inadequate air capacity for the CAAS building horns. CAAS alarm
. capabilities supplied by plant air were declared inoperable due to inaudibility; however, CAAS
~detectability was not affected. Because of rapid response to the unloading, restart of the compressor L
. occurred prior to implementation of appropriate Limiting Conditions of Operations (LCO) actions.
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On May 22,1998, at 1008 hrs., the Nuclear Regulatory Commission Headquarters (NRC-HQ) office was notified of this event in accordance with 10CFR76120(c)(2)(NRC Event 34277).
Dry compressed air is required at the Paducah Gaseous Diffusion Plant (PGDP) to operate pneumatic instruments, controllers, and valves for plant processes. Air is also used for plant support production operations, steam plant operations, test facilities, and maintenance functions. Dry compressed air
. is supplied from three buildings (C-600, -620, -335) and an auxiliary air supply is located in Building C-607. The air compressor facilities may be opemted separately or together to maintain
' air supply to the distribution headers. Dry compressed air is also used as' the primuy motive force
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to sound building horns. associated with CAAS. TI e requirements for compressed air capacity
. relative to CAAS requirements have been assessed in Engineering Notice (EN) EN-C-833-98-027, L
Rev. 0,' effective April 3,1998. Plant Utility Operations issued Long Term Order (LTO)
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- C600-98-01, Rev. 2, dated May 5,1998, to assure the initial conditions of the EN, including CAAS l
~ operability, are maintained. The LTO defines the expectation for on-line plant air availability to be 1 maintained at or above 11,250 scfm.
L At the time of the' event, there were severe thunderstorms in the vicinity of the plant. At
-approximately.1624 hrs., thunderstorms caused a surge in the compressor's electrical system resulting in compressor unloading. When a compressor unloads it is an indication that all, or a portion,-_of the inlet air has been bypassed or reduced which renders the compressor unable to compress. At approximately 1626 hrs., the compressor's electrical surge protector was reset and the i
- compressor retumed to normal operation. However, when the compressor unloaded it reduced the ~
plant air availability to less than 11,250 scfm. The CAAS was inoperable for approximately two minutes.
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Docket No. 70-7001 GDP 98-1045 Page 2 of 2 l
The safety significance of this event was a partial loss of the plant air supply affecting the CAAS l
' alarm capabilities supplied by plant air for approximately two minutes; however, CAAS detectability l
~. was not affected. - Additionally, the feed autoclave high pressure isolation valves in Building C-333-A and C-337-A which utilize plant air to assist in closure could be affected by the loss of air, although the valves are designed to fail in the safe (closed) position.
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Reliance on the plant air for CAAS audibility will be reduced in the future by the installation of air
. accumulators and air distribution piping that will be dedicated to supplying compressed air to the L
CAAS.
i CAUSE OF THE EVENT L
L A. Direct Cause The direct cause of the_ event 'was the temporary inoperability of an Ingersoll-Rand Centac i
centrifugal compressor. The inoperability of the compressor caused a partial loss of the plant air system and resulted in a CAAS inaudibility.
B.' Root Cause The root cause of this event was a system that was not designed to resist a natural phenomenon (severe thunderstorms) that resulted in a surge in the compressor's electrital system and actuated the surge protection.
CORRECTIVE ACTIONS-A. Planned Corrective Actions
- 1. By December 15,1998, Engineering will complete a construction project to reduce CAAS dependence on the existing air supply system by installing air accumulators and air distribution piping that will be dedicated to supplying compressed air to CAAS horns.
- EXTENT EXPOSURE OF INDIVIDUALS TO RADIATION OR RADIOACTIVE MATERIALS None
' I.ESSONS'LEARNEQ This event reinforced the value of surge protectors in precluding damage to equipment required to -
support safety systems that may be subjected to electrical surges.
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Docket No. 70-7001 GDP 98-1045
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Page1of1 Event Report ER-98-14 List of Commitments
- 1. By December 15,1998, Engineering will complete a construction project to reduce CAAS dependence on the existing air supply system by installing air accumulators and air distribution piping that will be dedicated to supplying compressed air to CAAS horns.
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