ML20206K648
| ML20206K648 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 05/07/1999 |
| From: | Jonathan Brown UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-99-2022, NUDOCS 9905130228 | |
| Download: ML20206K648 (4) | |
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' May 7,1999 -
GDP 99-2022 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
- Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 Event Report 99-06 Pursuant to 10 CFR 76.120(d)(2), Enclosure 1 provides a 30-day Event Report for an emergency condition that was declared an " Alert" at the Portsmouth Gaseous Diffusion Plant. An " Alert" was declared when a transformer tank ruptured and released oil to the switchyard cobble bed in the X-533 Switchyard. There are no commitments contained in this report.
Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.
Sincerely,
- 7ats $m J. Morris Brown General Manager Portsmouth Gaseous Diffusion Plant 1
Enclosures:
' As Stated.
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NRC Region III Office r
NRC Resident Inspector-PORTS 9905130228 990507
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' P.O. Box 800, Portsmouth, OH 45661
._ Telephone' 740-897 2255 Fax.740-897-2644 http://www.usec.com
- Offices in Livermore, CA L Paducah, KY Portsmouth, OH Washington, DC 1
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Enclosure li GDP 99-2022 -
Page' 1 of 3 s Event Report 99-06 Description of Event -
j On April 8,1999, at approximately 0521 hours0.00603 days <br />0.145 hours <br />8.614418e-4 weeks <br />1.982405e-4 months <br />, Gas Circuit Beakers 355 and 358 and Air Circuit =
Breakers 308T and 309T tripped offline, causing a loss of polwer to Transfonners T308 and T309.
. Operators investigating the loss of power discovered 'that the transformer tank'on Transformer T3092 had ruptured causing a release of transformer oil. The transformer is a 125-MVA 60 Hz Power' q
Transformer, Serial Number 7002358, manufactured by Westinghouse in 1975.1 The transformer oil spilled from the transformer and onto a bed oflimestone cobbles in the X-533A Switchyard.
y On April 8,1999, at 0555 hours0.00642 days <br />0.154 hours <br />9.176587e-4 weeks <br />2.111775e-4 months <br />, the Emergency Operations Center (EOC) was activated in response ~'
' to the ruptured transformer tank. At 0710 hours0.00822 days <br />0.197 hours <br />0.00117 weeks <br />2.70155e-4 months <br />, the Crisis Manager declared an " Alert"'due to concerns with the oil runoff escaping to the environment. At the time of the incident the transformer status was normal and no switching or maintenance was unkrway. The load on the transformer was less than one halfits rated capacity.
The transformer tank rupture resulted in the release of approximately 8,500 gallons of electrical insulating oil. The plant Environmental Compliance group confirmed that.the oil was fully..
contained in the X-2301-6 Environmental Holding Pond by an oil boom and floating weir. The oil -
was later recovered. No off-site environmental impact occurred as e. result of the oil release.
The oil released was a highly refined light mineral oil containingiDiteriarybutyl-p-cresol or Ditertiarybutylphenol stabilizer. The oil was installed in the transformer when it was positioned in j
the switchyard in March 1976.
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1 The incident caused the loss of power to seven X-333 process cells and to auxiliary substations.
1 During the incident there were no safety system failures or actuations. The incident was declared d
an " Alert" due to a concem with the runoff of oil. 'At the time the " Alert" declaration was made, it :
was not known if the oil would be contained and successfully recovered.
An emergency condition declared as an " Alert" is reportable in accordance with 10CFR76.120(a)(4);
The incident was reported to the NRC Operations Center at 0721 hours0.00834 days <br />0.2 hours <br />0.00119 weeks <br />2.743405e-4 months <br />. The event was'also reported to NRC in accordance with Safety Analysis Report 6.9, Table 6.9-1 P, because notification of the incident was made to the Ohio Environmental Protection Agency (OEPA) and a news release was issued.-
Cause of Event -
j The direct cause of the release of oil was the transfonner experienced a fault that caused the tank to~
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rupture and spill transformer oil.
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Enclosure !!
GDP 99-2022 -
- Page 2 'of 3 i
Event Report 99-06 On subsequent days following the event, Transformer T309 was inspected and extensive damage was '
found. Due to overpressurization, the transformer tank ballooned on two sides and on the top. - The a tank rupture occurred at the lower tank flange on the two sides that ballooned. ' Considerable internal damage was found in the "C" phase end of the unit where the fiber board structure supporting thi tapped leads comes from the "C" phase transformer near the center of the "C" phase winding. - _The' _.
secondary bus bar on "C" phase was found distorted and twisted by the force of the fault and.
evi ince of arcing was found in the low voltage end of the high voltage winding. Evidence of arcing was also found around the preventive auto transformer, the secondary buswork and the leads going :
to the primary neutral bushing
' A root cause cannot be determined until the transformer is untanked, disassembled and inspected to.
determine the extent of the damage and the cause for failure. The probable cause for the transformer failure is believed to be insulation damage, due to winding tap shift, attributable to through faults.
Further investigation into the cause for the transformer fault is ongoing. The investigation results and any corrective actions developed will be documented in accordance with the PORTS Corrective -
Action Program.
The bed of the X-533A Switchyard where the oil was released contains 1 to 3 feet of'2 to 3 inch limestone cobbles underlain by clay soils. Above the soils and below the limestone there is a series of French drains designed to remove precipitation runoff from the switchyard. An 8-inch openjoint tile beneath the transformer in the eastem half of the switchyard drains into a storm sewer, which flows into the X-230J-6 Environmental Holding Pond prior to discharging off-site to a creek via a drainage ditch. The pond itselfis designed.with contingency equipment (i.e., an oil boom and floating weir) to divert oil from the ' main pond to an adjacent oil diversion / containment impoundment. The oil diversion structure has a bafiled effluent system to contain the oil within the impoundment. These systems were successful in removing oil from the main pond to the oil diversion impoundment for subsequent removal with on-site vacuum trucks. Additional contingency.
measures were implemented by constructing a temporary earthen dam with an angled 12-inch.
corrugated metal pipe below the oil containment structure and plywood and sandbags were used at a culvert at the Northeast Bypass Road to provide additional temporary retention.-
At 0958 hours0.0111 days <br />0.266 hours <br />0.00158 weeks <br />3.64519e-4 months <br />, after. the "All Clear" was given on the emergency. response tolthe X-230J-6' Environmental Holding Pond, a Recovery Manager was assigned to monitor cleanup activities f associa'ed with the oil release. Approximately a 3)s-inch layer of oil was present on the main pond u
Tand I to 1 U4 inches in the oil diversion impoundment.' A representative from the OEPA Division of Emergency: and[Remedialj Response (Southeast District '_ Office),' arrived at PORTS at i
f approximately 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on. April 8,'1999. Cleanup activities continued thr'oughout the afternoon and during'the evening hours.1 By the moming of April 9,1999, most of the oil had been removed, g -
except for a visible l oil ~ sheen on the surface ~ of the holding pond. Runoff from precipitation '
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GDP 99-2022 s j
. Page 3 of 3.
Event Report 99-06
. commencing that' morning [ daily total of 0.50 inches of rainfall] caused the holding pond to; discharge, allowing an oil sheen to migrate.into the drainage ditch below the culvert; however, oil '
did not migrate off-site and no sheen or discolored water reached the waters of the State. Continued '
cleanup efforts (i.e., with oil absorbent pads) are ongoing when there is any visible sheen appearing c on the holding pond from residuals after precipitation events.. Analytical results for water samples
' collected approximately every four hours during the 24-hour period following the spill were below:-
the National Pollutant Discharge Elimination. System daily discharge limitation for oil and grease and Polychlorinated Biphenyls at this OEPA Permit Outfall.
Corrective Actions There were no nuclear safety concerns associated with the ruptured transformer and there was nof release of oil that reached the waters of the State. Corrective actions for the transformer failure will -
be determined and documented in accordance with the PORTS Corrective Action Program.
Extent of Exposure ofIndividuals to Radiation or Radioactive Materials There were no exposures to individuals from this incident to radiation or radioactive materials.
Lessons Learned from the Event The declaration of an " Alert" was effective in ensuring the event was properly assessed. Emergency response personnel were activated and stationed at their emergency duty stations to help mitigate the consequences of the oil release.
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