Information Notice 1986-15, Loss of Offsite Power Caused by Problems in Fiber Optics Systems

Loss of Offsite Power Caused by Problems in Fiber Optics Systems

ML031220597
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	03/10/1986
From:	Jordan E L NRC/IE
To:
References
IN-86-015, NUDOCS 8603050394
Download: ML031220597 (3)

SSINS No.: 6835HU OlIN 86-15UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555March 10, 1986IE INFORMATION NOTICE NO. 86-15: LOSS OF OFFSITE POWER CAUSED BY PROBLEMSIN FIBER OPTICS SYSTEMS

Addressees

All nuclear power reactor facilities holding an operating license (OL) or aconstruction permit (CP).

Purpose

This notice is to alert addressees to recent instances of loss of offsite powercaused by problems with fiber optics systems used to control switchyard circuitbreakers. Recipients are expected to review the information for applicabilityto their facilities and consider actions, if appropriate, to preclude similarproblems occurring at their facilities. However, suggestions contained in thisnotice do not constitute NRC requirements; therefore, no specific action orwritten response is required.

Description of Circumstances

Three recent instances of total loss of offsite power at nuclear power plantswere caused by problems with fiber optics control systems. Fiber optics systemsare sometimes thought to be immune to radio frequency interference problems.However, at least one of these instances was probably caused by interferencefrom a hand-held radio in close proximity to the tone relaying trip receivers ofthe fiber optics system.On October 3, 1985, the Palo Verde Unit 1 nuclear power plant tripped from 52percent power because of a total loss of offsite power. The loss of offsitepower was caused by the apparent malfunction of a multiplexer in the fiber opticssystem that in turn controlled breakers in the plant switchyard. The loss ofoffsite power caused the starting and loading of the emergency diesel generatorsthat restored power to the engineered safety features buses.On October 7, 1985, while shut down in Mode 3, Palo Verde Unit 1 again experienceda loss of offsite power apparently because of a failure of the multiplexer.Although some failed components were identified, the ultimate cause of thesefailures of the fiber optics multiplexer was never determined. As a correctivemeasure, control of the affected switchyard breakers was hardwired and themultiplexer control was bypassed.8603050394 IN 86-15March 10, 1986 On January 1, 1986, the River Bend nuclear power station experienced a totalloss of offsite power caused by the tripping of the preferred station transformersA and C at 0941, and approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> later, the tripping of the preferredstation transformers B and D. The plant was shut down at the time because ofa reactor scram that occurred approximately 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> earlier for unrelated reasons.Investigation indicated that the loss of offsite power event was not caused bya valid signal. Testing did show that hand-held radios could have caused theloss of offsite power event. Two hand-held radios, one 4 watts at 150 MHz andthe other 5 watts at 450 MHz, caused system trips when keyed within 12 feet ofthe transmitters and receivers for the fiber optics system. Mobile radios ofgreater power located outside the building containing the fiber optics systemwould not cause spurious trips.At River Bend, the fiber optics transmitting and receiving equipment is locatedin the turbine building and the Fancy Point substation, a distance of about 0.8miles. The corrective measures adopted at River Bend include shielding of thefiber optics transmitters and receivers, posting signs that prohibit use ofradios near the fiber optics equipment, rewiring the equipment so that twochannels instead of one are required for tripping, providing control roomannunciation of system status, training personnel on restricted use of radios,installing a sequence-of-events recorder to diagnose any future events, andtraining personnel on resetting lockouts, including posting of operator aids.Other problems caused by use of hand-held radios in nuclear power plants werediscussed in IE Information Notice No. 83-83, "Use of Portable Radio TransmittersInside Nuclear Power Plants," published on December 19, 1983.No specific action or written response is required by this information notice.If you have questions about this matter, please contact the Regional Adminis-trator of the appropriate NRC regional office or this office.EdwarqV. Jordan, DirectorDivisi of Emergency Preparednessand Engineering ResponseOffice of Inspection and Enforcement

Technical Contact:

Eric Weiss, IE(301) 492-9005Attachment: List of Recently Issued IE Information Notices

iAttachment 1IN 86-15March 10, 1986LIST OF RECENTLY ISSUEDIE INFORMATION NOTICESInformation Date ofNotice No. Subject Issue Issued to86-1486-1386-1286-1184-69Sup. 1PWR Auxiliary Feedwater PumpTurbine Control ProblemsStandby Liquid ControlSystem Squib Valves FailureTo FireTarget Rock Two-Stage SRVSetpoint DriftInadequate Service WaterProtection Against Core MeltFrequencyOperation Of Emergency DieselGeneratorsSafety Parameter DisplaySystem MalfunctionsFailure Of Check And StopCheck Valves Subjected ToLow Flow ConditionsLicensee Event Report (LER)Format ModificationLack Of Detailed InstructionAnd Inadequate Observance Of3/10/862/21/862/25/862/25/862/24/862/13/862/3/862/3/862/3/86All power reactorfacilities holdingan OL or CPAll BWR facilitiesholding an OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CPAll power reactorfacilities holdingan OL or CP86-1086-0986-0886-07Precautions During MaintenanceAnd Testing Of Diesel GeneratorWoodward GovernorsOL = Operating LicenseCP = Construction Permit