Information Notice 1992-09, Overloading and Subsequent Lock Out of Electrical Buses During Accident Conditions

Overloading and Subsequent Lock Out of Electrical Buses During Accident Conditions

ML031200714
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	01/30/1992
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-92-009, NUDOCS 9201240235
Download: ML031200714 (3)

UNITED STATES

NUCLEAR REGULArORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 January 30, 1992 NRC INFORMATION NOTICE 92-09: OVERLOADING AND SUBSEQUENT LOCK OUT OF

ELECTRICAL BUSES DURING ACCIDENT CONDITIONS

Addressees

permits for nuclear power

All holders of operating licenses 6toJMnstruett0n

reactors.

92 FEa 13 A8:49

Purpose

The U.S. Nuclear Regulatory Comnission (NRC) is issuing this information notice

identified by a licensee whereby

to alert addressees to a particular scenario accident conditions, deenergized, electrical buses could be overloaded during expected that recipients will

and prevented from being reenergized. Ittoistheir facilities and consider

review the Information for applicability problems. However, suggestions

actions, as appropriate, to avoid similarnot NRC requirements; therefore, no

contained in this information notice is are

specific action or written response required.

Description of Circumstances

On November 21, 1991, the Power Authority for Unitthe State of New York, the

3, reported that the vital

licensee for Indian Point Nuclear Generating (LOCA) as a

buses could bWcome overloaded during a loss-of-coolant-accident

directing operators to restore non- result of emergency operating procedures power is not lost. The procedure would

essential loads to the buses if offsite loads being powered concurrently

result inboth emergency and non-emergency calculations reveal that performing

from the same bus. The licensee's recent The resulting overcurrent condition

this procedure could have overloaded buses.

the bus and prevent it from being

could lock out a bus (i.e., deenergize the associated emergency diesel generator).

reenergized from any source including

Discussion

condition in power demand for

A LOCA is generally analyzed as the most limiting loads are added to the power

onsite electrical systems. When non-essential electrical buses and breakers could

system under this most demanding condition,system recognizes such an overloaded

be overloaded. The electrical protection and locks out the bus. The dc-powered

condition as an electrical fault on a bus

breaker controls retain the faulted condition, and the emergency diesel generator

relays are manually

will not be able to energize the bus until protective trains of safety-related

reset. The scenario could result in disabling redundant

equipment.

9201240235 p

• WI

IN 92-09 January 30, 1992 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

o &Dbec

Division of Operational Events Assessment

office of Nuclear Reactor Regulation

Technical contact: Thomas Koshy

(301) 504-1176 Attachment: List of Recently Issued NRC Information Notices

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____ 11 -

9 r

Attachment

IN 92-09 January 30, 1992 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

92-08 Revised Protective Action 01/23/92 All fuel cycle and materi- Guidance for Nuclear Inci- als licensees authorized

dents to possess large quanti- ties of radioactive materi- ial.

92-07 Rapid Flow-Induced Erosion/ 01/09/92 All holders of OLs or CPs

Corrosion of Feedwater Piping for pressurized water

reactors.

92-06 Reliability of ATWS Mitiga- 01/15/92 All holders of OLs or CPs

tion System and Other NRC for nuclear power reactors.

Required Equipment Not

Controlled by Plant Tech- nical Specifications

42-05 Potential Coil Insulation 01/08/92 All holders of OLs or CPs

Breakdcwn in ABB RXMH2 Relays for nuclear power reactors.

92-04 Potter & Brumfield Model 01/06/92 All holders of OLs or CPs

MDR Rotary Relay Failures for nuclear power reactors.

92-03 Remote Trip Function 01/06/92 All holders of OLs or CPs

Failures in General Electric for nuclear power reactors.

F-Frame Molded-Case Circuit

Breakers

92-02 RelapS/Mod3 Computer Code 01/03/92 All holders of OLs or CPs

Error Associated with the for nuclear power reactors.

Conservation of Energy

Equation

92-01 Cable Damage Caused by 01/03/92 All holders of OLs or CPs

Inadequate Cable Installa- for nuclear power reactors.

tion Procedures and Controls

91-87 Hydrogen Etbrittlement of 12/27/91 All holders of OLs or CPs

Raychem Cryofit Couplings for nuclear power reactors.

L a Operating License

P a Construction Permit