Information Notice 1998-07, Offsite Power Reliability Challenges from Industry Deregulation

Offsite Power Reliability Challenges from Industry Deregulation
	ML031050278
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:	02/27/1998
From:	Roe J; Office of Nuclear Reactor Regulation
To:	;
References
	IN-98-007, NUDOCS 9802240067
	Download: ML031050278 (7)
	v • d • e

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 February 27, 1998 NRC INFORMATION NOTICE 98-07: OFFSITE POWER RELIABILITY CHALLENGES FROM

INDUSTRY DEREGULATION

Addressees

All holders of operating licenses for nuclear power reactors except those who have ceased

operations and have certified that fuel has been permanently removed from the vessel.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to a potential concern relating to electric power industry deregulation that could

adversely affect the reliability of offsite power sources, i.e., power from the transmission system

grid to nuclear power plants. It is expected that recipients will review the information for

applicability to their facilities and consider actions, as appropriate. However, suggestions

contained in this information notice are not NRC requirements; therefore, no specific action or

written response to this notice is required.

Description of Circumstances

On July 11, 1989, safety systems at Virgil C. Summer Nuclear Station experienced a sustained

degraded voltage condition and as a result the safety buses were automatically transferred from

the offsite power system to onsite standby diesel generators. The degraded condition was

caused by a turbine trip and deficiencies in the offsite power system's transmission network

equipment. The transfer of power supplies was initiated by operation of degraded voltage

protective relays, as designed. Non-safety system loads remained operable while being powered

for approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from the degraded offsite power source. (LER 50-395/89-012)

On November 5, 1991, the licensee for Arkansas Nuclear One, Units 1 and 2 reported that, had

its 500kV auto-transformer been lost during summer peak conditions, the 161kV system might

not have been able to maintain adequate voltages to support the operation of the safety system

loads of both units. (LER 50-313/91-010)

On April 15, 1992, Northeast Nuclear Energy Company reported that under certain operating

conditions of the transmission network (i.e., during heavy load conditions), a failure of

transmission system equipment may cause a trip of all three Millstone units and a loss of offsite

power to the station. This operating condition was precipitated by the economic displacement

of oil-fired generating units by non-utility generators and by the addition of other generating

capacity (Seabrook and Hydro-Quebec) to the transmission network. (LER 50-245/92-020)

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IN -07 February 27, 1998 On April 14, 1993, Wisconsin Public Service Corporation reported that under certain transmission

line contingencies, a potential existed for the Kewaunee Nuclear Power Plant grid to become

unstable and cause all offsite power sources into the plant to trip. (Ref: LER 50-305/93-010)

On December 30, 1993, Northeast Nuclear Energy Company reported that under certain

operating conditions of the transmission network (i.e., Millstone Units 2 and 3 off line), the

transmission network may not have sufficient capacity to permit the continued operation of safety

system loads from offsite sources following a trip of Millstone Unit 1. (LER 50-245/94-001)

On August 8, 1995, Pacific Gas and Electric Company (PG&E) reported that under certain

operating conditions (i.e., a high system load with a specific 230kV transmission line out of

service), the transmission network may not have sufficient capacity to permit the continued

operation of the safety system loads from offsite sources following a trip of one of the two Diablo

Canyon units. (Ref: LER 50-275/95-007)

On August 10, 1996, a transmission line sagged into a tree in Oregon creating a ground fault that

progressed into a major fault on the western Interconnection. The subsequent transient resulted

in the tripping of both Diablo Canyon, Units 1 and 2 (LER 50-275/96-012) and Palo Verde, Units 1 and 3 (LER 50-528/004).

During the summer of 1997, concerns were expressed about the impact of electric peak

conditions on the offsite power sources for nuclear power plants located in the Midwest and

New England. In addition, the licensee for Clinton nuclear station sought an exemption from

offsite power regulatory requirements because of its analysis that offsite power would become

inadequate under certain summer peak conditions following the loss of the nuclear unit.

Recent NRC inspection findings and Licensee Event Reports have indicated instances when grid

stability analyses had not been updated by the licensees to reflect changes in the grid power

system. Office for Analysis and Evaluation of Operational Data study C97-01, "Grid Performance

Factors" dated March 20, 1997, identified a Oneed to monitor grid conditions on a regular basis."

Discussion

In 1988, NRC issued the station blackout (SBO) rule. The requirements of 10 CFR 50.63, "Loss

of All Alternating Current Power," specify that each light-water-cooled nuclear power plant be

able to withstand and recover from an SBO (i.e., a loss of offsite and onsite emergency ac power

sources) for a specified period. The NRC review of licensees' analyses to assess the

vulnerability of offsite power and the time required for recovery indicated that for most nuclear

power plant sites the grid was stable and reliable.

Historically, grid control is decentralized and each utility or a small group of utilities forms a

control area containing customers for which it Is jurisdictionally responsible. The control areas

form reliability councils that establish operating standards by consensus. These agreements, in

turn, became the factors that determine the reliability of the grid and the bases for the availability

of the offsite power system. Although the grid operating standards that evolved in the past

provided reasonable grid reliability, events like those discussed herein reveal vulnerabilities of

the electrical grid either through actual challenges or through licensee's analyses to assess the

adequacy of the offsite power system.

INS '7 Feb,--dry 27, 1998 The present grid management may be dismantled or restructured by two factors that are

emerging: non-utility generation and deregulation. It Is anticipated that in the future, power

suppliers, whether utilities or independent power producers, will actively compete for sales to

customers who may be located anywhere on the power grid. This option creates multiple

combinations of generating units going on and off the grid based on economic and performance

related consequences. Regional grid control could be the responsibility of centralized

independent system operators (ISOs). The responsibilities and authority of an ISO are yet to be

defined, but It is expected that the ISO, or a similar entity, will be charged with maintaining grid

reliability to facilitate the marketing of power. It is uncertain how the historic mechanisms for

reliable operation will change under the new grid operational structure. The Department of

Energy has sponsored a Task Force on Electric System Reliability to examine the implications of

industry deregulation on the Nation's electric power supply.

The capacity and capability of the offsite power system for each nuclear power plant could be

significantly influenced by the decisions emerging from these forthcoming changes. Since the

capability of the offsite power cannot be tested except when challenged in an actual event, the

design bases of the offsite power can only be assured through an enveloping analysis that

accounts for the full spectrum of grid loading and transient conditions that support the operability

of safety systems. The NRC Standard Review Plan Section 8.2 provides current guidance for

assessing the adequacy of the offsite power system. It addresses grid analyses that

demonstrate acceptable voltage and frequency when subjected to scenarios involving loss of

nuclear unit generation, loss of the largest other unit, or loss of the most critical transmission line.

Although the above events discussed may not demonstrate present generic weaknesses in

licensees' processes, it is vital that licensees continue to ensure that the design bases with

respect to the reliability and stability of the offsite power sources do not degrade during the life of

the nuclear facility. The capacity and capability of the offsite power system for nuclear power

plants are important elements to be factored into the management of the changes resulting from

industry deregulation.

This information notice requires no specific action or written response. If you have any questions

about the information in this notice, please contact one of the technical contacts listed below or

the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

orig /s/'d by

Jack W. Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical Contacts: Ronaldo V. Jenkins, NRR Thomas Koshy, NRR

301415-2985 301415-1 176 E-Mail: rvj2nrc.gov E-Mail: txk@nrc.gov

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AEOD Idc 2/12/98 (E.Rossi) & Tech Editor 1/27/98 DOCUMENT NAME: S:%DRPM SEC\98-07.IN - SEE PREVIOUS CONCURRENCE

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Attachment

IN 98-07 February 27, 1998 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

98-06 Unauthorized Use of Ucense to 2/19198 All NRC licensees authorized to

Obtain Radioactive Materials, possess licensed material

And Its Implications Under The

Expanded Title 18 of the

U.S. Code

97-45, Supp. 1 Environmental Qualification 2/17/98 All holders of operating

Deficiency for Cables and licenses for nuclear power

Containment Penetration reactors except those licensees

Pigtails who have permanently ceased

operations and have certified that

the fuel has been permanently

removed from the reactor vessel

98-05 Criminal History Record 2111/98 All holders of operating

Information licenses for power reactors

98-04 1997 Enforcement Sanctions for 2/9/98 All U.S. Nuclear Regulatory

deliberate Violations of NRC Commission licensees

Employee Protection requirements

98-03 Inadequate Verification of 1/21/98 All holders of operating licenses

Overcurrent Trip Setpoints in for nuclear power reactors

Metal-Clad, Low-Voltage

Circuit Breakers

98-02 Nuclear Power Plant Cold 1/21/98 All holders of operating licenses

Weather Problems and for nuclear power reactors

Protective Measures

98-01 Thefts of Portable Gauges 1/15/98 All portable gauge licensees

97-91 Recent Failures of Control 12/31/97 All industrial radiography

Cables Used on Amersham licensees

Model 660 Posilock Radiography

Systems

97-90 Use of Nonconservative 12/30/97 All holders of OLs for nuclear

Acceptance Criteria in power reactors except those

Safety-Related Pump who have ceased operations

Surveillance Tests and have certified that fuel has

been permanently removed from

the vessel

OL = Operating License

CP = Construction Permit

IN9' Y