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 NRC/IE
To:
References
IN-86-015, NUDOCS 8603050394
Download: ML031220597 (3)

SSINS No.: 6835 HU OlIN 86-15 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 March 10, 1986 IE INFORMATION NOTICE NO. 86-15: LOSS OF OFFSITE POWER CAUSED BY PROBLEMS

IN FIBER OPTICS SYSTEMS

Addressees

All nuclear power reactor facilities holding an operating license (OL) or a

construction permit (CP).

Purpose

This notice is to alert addressees to recent instances of loss of offsite power

caused by problems with fiber optics systems used to control switchyard circuit

breakers. Recipients are expected to review the information for applicability

to their facilities and consider actions, if appropriate, to preclude similar

problems occurring at their facilities. However, suggestions contained in this

notice do not constitute NRC requirements; therefore, no specific action or

written response is required.

Description of Circumstances

Three recent instances of total loss of offsite power at nuclear power plants

were caused by problems with fiber optics control systems. Fiber optics systems

are sometimes thought to be immune to radio frequency interference problems.

However, at least one of these instances was probably caused by interference

from a hand-held radio in close proximity to the tone relaying trip receivers of

the fiber optics system.

On October 3, 1985, the Palo Verde Unit 1 nuclear power plant tripped from 52 percent power because of a total loss of offsite power. The loss of offsite

power was caused by the apparent malfunction of a multiplexer in the fiber optics

system that in turn controlled breakers in the plant switchyard. The loss of

offsite power caused the starting and loading of the emergency diesel generators

that restored power to the engineered safety features buses.

On October 7, 1985, while shut down in Mode 3, Palo Verde Unit 1 again experienced

a loss of offsite power apparently because of a failure of the multiplexer.

Although some failed components were identified, the ultimate cause of these

failures of the fiber optics multiplexer was never determined. As a corrective

measure, control of the affected switchyard breakers was hardwired and the

multiplexer control was bypassed.

8603050394

IN 86-15 March 10, 1986 On January 1, 1986, the River Bend nuclear power station experienced a total

loss of offsite power caused by the tripping of the preferred station transformers

A 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 preferred

station transformers B and D. The plant was shut down at the time because of

a 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 by

a valid signal. Testing did show that hand-held radios could have caused the

loss of offsite power event. Two hand-held radios, one 4 watts at 150 MHz and

the other 5 watts at 450 MHz, caused system trips when keyed within 12 feet of

the transmitters and receivers for the fiber optics system. Mobile radios of

greater power located outside the building containing the fiber optics system

would not cause spurious trips.

At River Bend, the fiber optics transmitting and receiving equipment is located

in the turbine building and the Fancy Point substation, a distance of about 0.8 miles. The corrective measures adopted at River Bend include shielding of the

fiber optics transmitters and receivers, posting signs that prohibit use of

radios near the fiber optics equipment, rewiring the equipment so that two

channels instead of one are required for tripping, providing control room

annunciation of system status, training personnel on restricted use of radios, installing a sequence-of-events recorder to diagnose any future events, and

training personnel on resetting lockouts, including posting of operator aids.

Other problems caused by use of hand-held radios in nuclear power plants were

discussed in IE Information Notice No. 83-83, "Use of Portable Radio Transmitters

Inside 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, Director

Divisi of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Eric Weiss, IE

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

i

Attachment 1 IN 86-15 March 10, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-14 PWR Auxiliary Feedwater Pump 3/10/86 All power reactor

Turbine Control Problems facilities holding

an OL or CP

86-13 Standby Liquid Control 2/21/86 All BWR facilities

System Squib Valves Failure holding an OL or CP

To Fire

86-12 Target Rock Two-Stage SRV 2/25/86 All power reactor

Setpoint Drift facilities holding

an OL or CP

86-11 Inadequate Service Water 2/25/86 All power reactor

Protection Against Core Melt facilities holding

Frequency an OL or CP

84-69 Operation Of Emergency Diesel 2/24/86 All power reactor

Sup. 1 Generators facilities holding

an OL or CP

86-10 Safety Parameter Display 2/13/86 All power reactor

System Malfunctions facilities holding

an OL or CP

86-09 Failure Of Check And Stop 2/3/86 All power reactor

Check Valves Subjected To facilities holding

Low Flow Conditions an OL or CP

86-08 Licensee Event Report (LER) 2/3/86 All power reactor

Format Modification facilities holding

an OL or CP

86-07 Lack Of Detailed Instruction 2/3/86 All power reactor

And Inadequate Observance Of facilities holding

Precautions During Maintenance an OL or CP

And Testing Of Diesel Generator

Woodward Governors

OL = Operating License

CP = Construction Permit