Information Notice 1985-77, Possible Loss Emergency Notification System Due to Loss of AC Power

Possible Loss Emergency Notification System Due to Loss of AC Power

ML031180335
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, 05000345, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	09/20/1985
From:	Jordan E NRC/IE
To:
References
IN-85-077, NUDOCS 8509180410
Download: ML031180335 (4)

SSINS No. 6835 IN 85-77 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 September 20, 1985 IE INFORMATION NOTICE NO. 85-77: POSSIBLE LOSS OF EMERGENCY NOTIFICATION

SYSTEM DUE TO LOSS OF AC POWER

Addressees

All holders of a nuclear power plant operating license (OL) or a construction

permit (CP).

Purpose

This information notice is provided to alert licensees to the possibility that

modifications to plant telephone systems may result in a change in the vulnera- bility of the Emergency Notification System (ENS) and other plant telephones to

losses of ac power. It is expected that recipients will 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 information notice do not constitute NRC requirements;

therefore, no specific action or written response is required.

Description of Circumstances

On January 8, 1984, the Palisades Nuclear Plant interrupted its offsite power

supply for maintenance activities. Subsequently all ac power from the emergen- cy diesel generators was lost. (This event is described in detail in Informa- tion Notice No. 84-42.) As a result of the ac power problems, all onsite

telephones were rendered inoperable for approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, except for two

offsite-powered pay telephones. Loss of the ENS and normal communications

significantly hampered the notification process.

On May 7, 1985, Quad Cities Unit 1 was operating at 90% power. The Unit 2 auxiliary transformer was inadvertently shorted while the unit was shut down

with its associated emergency diesel generator out for maintenance. This

caused the loss of offsite ac power to Unit 2 and a voltage transient in Unit 1 that subsequently caused that unit to scram about 15 minutes later. Unit 1 retained offsite ac power. One division of Unit 2 was promptly powered by

autostart of the swing emergency diesel generator, and the other division was

powered within about 20 minutes by crosstie to a 4kV bus of Unit 1. When the

licensee attempted to notify the NRC Emergency Operations Center over the ENS,

the circuit repeatedly disconnected. The Quad Cities plant also was unable to

receive incoming calls from the NRC over commercial telephone lines.

8509180410

IN 85-77 September 20, 1985 These incidents indicate that the provisions of IE Bulletin 80-15 were not

maintained at the affected facilities at the times of the events. The bulletin

required verification that all ENS station packages that use onsite ac power

were connected to a safeguards instrumentation bus backed up by automatic trans- fer to batteries and an inverter or an equally reliable power source. At the

time the bulletin was issued, both plants had ENS packages that were powered by

the local telephone company, making them independent of ac power sources at the

plant sites.

Discussion:

The installation of the ENS requires a station package that operates on 110

Vac. In some cases, the station package is located at the local telephone

company which supplies the required power for normal operation and emergency

power for operation during abnormal situations. However, in many cases, the

ENS package is located at the site and is served by ac power provided by the

plant.

Earlier incidents involving loss of offsite power led to losses of emergency

notification capabilities at the Davis-Besse facility on October 15, 1979, and

at the Indian Point Unit 2 on June 3, 1980. These incidents prompted the

issuance of IE Circular 80-09 and IE Bulletin 80-15. The bulletin contained a

list of those stations with ENS packages powered by the telephone company and a

list of those stations with ENS packages powered at the plant site. At that

time, both the- Palisades plant and the Quad Cities plant had ENS packages with

power supplies provided by the telephone company.

Subsequent changes to provide additional circuits in the telephone system at

the Palisades plant resulted in the ENS and commercial telephone system packag- es being powered at the plant site. Power was supplied from a bus supported by

an emergency diesel generator. However, the modification was not controlled

within the licensee's formal- modification process and was thus completed

without formal review. The modified ENS power supply was not backed by batter- ies and an inverter, as previously provided by Bulletin 80-15, and was not

independent of the station's commercial telephone service as reflected in the

licensee's Emergency Plan.

During the incident at Palisades on January 8, 1984, the unit was intentionally

powered from a single emergency diesel generator on the IC 2400-V bus to allow

isolation of a faulty switchyard breaker. The unit was defueled, and the other

diesel was inoperable due to maintenance. When the running diesel subsequently

overheated and tripped, the station was without ac power with the exception of

preferred ac. Although some other buses were repowered by offsite ac within

an hour, difficulties in closing the breakers to the iC and 1E 2400-V buses

resulted in the extended loss of all telephones except for two pay telephones

powered by the telephone company. The 1E bus was repowered after about 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />

by successfully closing the breaker to the offsite source. This provided par- tial restoration of the telephone service. However, the ENS telephones on the

iC bus were not restored for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, when they were finally jumpered to an

energized source.

- -IN 85-77 September 20, 1985 At the Quad Cities plant, the local telephone company abandoned the copper wire

cables that were in use in 1980 and installed a fiber optics communications

system in its place. Because the fiber optics cable does not provide for

electrical power transmission, the fiber optics package at the plant had to be

provided with an onsite power source. Similarly, the site package for the ENS

had to be shifted to onsite power. The licensee powered the fiber optics

package from an instrument bus in Unit 2 and the ENS from an instrument bus in

Unit 1. These buses are supported by emergency diesel generators, but the

power supplies to the communications packages are not backed up by batteries

and an inverter in accordance with Bulletin 80-15.

During the event on May 7, 1985, when the Unit 2 instrument bus powering the

fiber optics package lost power, both the ENS and normal PBX telephones became

inoperable. The Unit 1 bus supporting the ENS package remained powered by an

offsite ac source through the switchyard, but could not communicate through the

unpowered fiber optics system. Once power was restored to the Unit 2 bus

through a crosstie, the ENS circuit repeatedly disconnected as the licensee

attempted to make emergency notifications.

These events illustrate the need for careful review of changes to plant

telephone equipment to ensure that the reliability of the ENS is not compro- mised. In those cases where offsite communications power that is supplied by

the telephone company is replaced by an onsite power source, it is important

to consider the reliability of the power sources for all segments of the ENS

transmission path. Those plants that already supply the ENS from an onsite

safeguards instrumentation bus should be aware that the introduction of a fiber

optics connection by the local telephone company still may compromise the ENS

if the plant-end fiber optics package is not similarly powered.

No specific action or written response is required by this information notice.

If you have any questions regarding this matter, please contact the Regional

Administrator of the appropriate NRC regional office or this office.

Divisio Emergency Preparedness

and E neering Response

Office of Inspection and Enforcement

Technical Contacts: S. Long, IE

(301) 492-7159 R. Priebe, IE

(301) 492-4333 Attachment: List of Recently Issued IE Information Notices

Attachment 1 IN 85-77 September 20, 1985 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

85-76 Recent Water Hammer Events 9/19/85 All power reactor

facilities holding

an OL or CP

85-75 Improperly Installed Instru- 8/30/85 All power reactor

mentation, Inadequate Quality facilities holding

Control And Inadequate Post- an OL or CP

modification Testing

85-74 Station Battery Problems 8/29/85 All power reactor

facilities holding

an OL or CP

84-70 Reliance On Water Level 8/26/85 All power reactor

Sup. 1 Instrumentation With A facilities holding

Common Reference Leg an OL or CP

85-73 Emergency Diesel Generator 8/23/85 All power reactor

Control Circuit Logic Design facilities holding

Error an OL or CP

85-72 Uncontrolled Leakage Of 8/22/85 All power reactor

Reactor Coolant Outside facilities holding

Containment an OL or CP

85-71 Containment Integrated Leak 8/22/85 All power reactor

Rate Tests facilities holding

an OL or CP

85-70 Teletherapy Unit Full 8/15/85 All material

Calibration And Qualified licensees

Expert Requirements (10 CFR

35.23 And 10 CFR 35.24)

85-69 Recent Felony Conviction For 8/15/85 All power reactor

Cheating On Reactor Operator facilities holding

Requalification Tests an OL or CP

85-68 Diesel Generator Failure At 8/14/85 All power reactor

Calvert Cliffs Nuclear facilities holding

Station Unit 1 an OL or CP

OL = Operating License

CP = Construction Permit