ML20137S008
| ML20137S008 | |
| Person / Time | |
|---|---|
| Issue date: | 04/08/1997 |
| From: | Callan L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Diaz N, Dicus G, Shirley Ann Jackson, Mcgaffigan, Rogers K, The Chairman NRC COMMISSION (OCM) |
| References | |
| NUDOCS 9704140330 | |
| Download: ML20137S008 (5) | |
Text
j o-q UNITED STATES o
NUCLEAR RE2ULATORY COMMISSION D
E WAsHINOToN. o.C. 20566 4 001 April 8, 1997 MEMORANDUM TO:
Chairman Jackson Commissioner Rogers Commissioner Dicus Commissioner Siaz Commissioner McGaffigan FROM:
L. Joseph Callan Executive Director fo perations
SUBJECT:
CASE STUDY-GRID PERFORMANCE FACTORS
~ Attached is the final AEOD Case Study, " Grid Performance Factors." This study was issued as a draft for peer review to industry organizations and within the NRC in July 1996. The attached final report has been revised to reflect the comments received.
The report has been distributed throughout the NRC and has been se to the public document room. It is being sent to you in preparation for the Commi;C.a Briefing on Electrical Grid Reliability on April 23,1997.
i This study was initiated to examine factors affecting the reliability of offsite power by collecting current operating experience and providing background information on grid performance and the impact of grid performance on nuclear power plants.
The North American Electric Reliability Council (NERC) has adopted programs and procedures to deal with forecasting, normal operations, emergency conditions, and recovery from system collapse. They have developed programs and procedures for orderly operation. There are reliability constraints on the individual systems which include, but are not limited to, low reserve margins, a shortage of transmission facilities, and technical j
problems in transmitting power over long lines. The grid, the bulk power supply, as managed by the NERC members, has adequate resources to give reasonable assurance that the reliability of the system will be maintained under normal conditions. On the whole, the grid is stable and reliable.
With respect to the electrical grid, the Standard Review Plan states, "The basic requirement is that loss of the largest operating unit on the grid will not result in loss of grid stability and availability'of offsite power to the plant under consideration." The Virgil i
Summer final safety analysis report states " Stability study results have demonstrated that j
the system is stable for (1) the loss of the unit generator, (2) the loss of the largest system
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OWS CONTACT:
Mary S. Wegner, AEOD/SPD/RAB RO-N>gi (301)415-6369 S T k.
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, generating unit,'and'(3) the loss of the most limiting transmu <n line." However, in 1989 work on the Virgil Sum'mir generator caused the reactor 'o tn,s. The nearby plants could.
not make up for the' Summer load loss and the failure generated a cascading grid effect that resulted in the loss of 16 generating units. Subsequently, the Summer safety busses Isolated fro'm offsite power due to low voltage on the grid. The emergency diesel-
! ' generators supplied power to their associated safety busses for about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
The AEOD report did identify several other events where offsite power to nuclear plants was challenged due to grid disturbances. In most cases, the result was a plant trip without loss of offsite power. Other problems described in the regional assessments as stated in Section 4 of the study are also of concern.
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l-In addition to operating experience, the report found that Arkansas Nuclear One Unit 1; Haddam Neck and Millstone Units 1,2, and 3: Salem Units 1 and 2 and Hope Creek; and LPoint Beach Units 1 and 2 and Kewaunee, after reviewing their grid analyses, discovered
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potential instability problems for certain situations. Licensee corrective actions included
_ power testrictions for certain grid conditions.
i The condition of the grid is dynamic, due to factors such as increased demand, decreasing margins, changing transmission patterns, aging equipment, non-utility generation, increased competition, industry restructuring, and deregulation. Many of these factors are different now than they were when the current nuclear plants were licensed.
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AEOD staff recommendation is to request licensees to confirm that they continue to meet
. their licensing bases with respect to the stability and reliability of offsite electric power.
The NRR staff is considering the course d action for this recommendation.
AEOD plans to monitor losses of offsite pnwer to determine trends and the need for appropriate actions. The staff has met with the Department of Energy, NERC, the Federal
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Energy Regulatory Commission, the Connecticut Valley Electric Exchange, Commonwealth Edison, the Edison Electric Institute, and the New England Power Pool to discuss the impending changes in the grid. The meetings are intended to provide additional insights into the complex problems that are inherent in assuring reliability in the changing industry.
Attachment:
Grid Performance Factors Study cc w/ attachment:
SECY L,,
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- e Distribution: See attached page
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" DOCUMENT NAME:; C:\\WP51\\WPDOCS\\ STUDIES \\COMMGRID.LTR
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~ generating unit, and (3) the loss of the most limiting transmission line.".HoweveJ,/ n 1989 f
i work on the Virgil Summer generator caused the reactor to trip. The nearby plants could
~
not make up for the Summer load loss and the failure generated a cascading glid effect
- that resulted in the loss of 16 generating units. Subsequently, the Summer fafety busses f
isolated from offsite power due to low voltage on the grid. The emergenpy diesel-generctors supplied power to their associated safety busses for about 2, hours.
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The AEOD report did identify several other events where offsite pow 6r to nuclear plants was challenged due to grid disturbances. In most cases, the result'was a plant trip b
without loss of offsite power. Other problems described in the re'gional assessments as stated in Section 4 of the study are also of concern.
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in addition to operating experience, the report focad that A ansas Nuclear One Unit 1; Haddam Neck and Millstone Units 1,2, and 3: Salem Unit $ 1 and 2 and Hope Creek; and Point Beach Units 1 and 2 and Kewaunee, after review'iph their grid analyses, discovered
~ potential instability problems for certain situations. Licensee corrective actions included L
power restrictions.for certain grid conditions.
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The condition of'thh grid is dynamic, due to factors such as increar,ed demand, decreasing l
margins, changing transmission patterns, aging,dquipment, non-utility generation, increased competition, industry' restructuring,'s'nd'denegulation. Many of these factors are i
different now than they were~when the curr t nuclear plants wert, licensed.
e AEOD' staff recommendation i.s to request' licensees to confirm that they continue to meet l
l their licensing bases with respect to' the' stability and reliability of offsite electric power.
)
The NRR staff is considering the cours 'of action for this recommendation.
monitor losses of[offsite power to determine trends and the need 1
The staff plans appropriate actions, The staff has' met with the Department of Energy, NERC, the Federal Energy Regulatory Commission,jhe Connecticut Valley Elvtric Exchange, Commonwealth 4
Edison, the Edison Eiectric Institute, and the New Englar. ^ Ner Pool to discuss the impending chanpes in the grjd. The meetings are intended to providc additional insights into the complex problems,,that are inherent in assuring reliability in the changing industry.
/
Attachment:
Grid Performance Factors Study cc w/ attachment:
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SECY Distribution > See attached page
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DOCUMENT NAME: C:\\W P51 \\WPDO C S\\STU DI E S\\CO MMG RID.LTR
- See evious concurrence:
l To e sepy of thle sleewment,inalleate in the hes: 'C' = Copy w6thout ettechnwnt/encloeu,e "E' = Copy wtth ettschment/enclosu,e
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CRossi Dross SCollins LJCallan -
DATE.
03/31/97*
03/31/97*
04/01/97*
04/ /97 04/ /97 OFFICinL RECORD COPY ac y/s/97 j
i-3 Chairman Jackson, et al. i I
The staff plans to monitor losses of offsite power to determine trends and the'need for appropriate actions. The staff has met with the Department of Energy, NERC, the Federal Energy Regulatory Commission, and the Connecticut Valley Exchange, and will be meeting with Commonwealth Edison and the Edison Electric Institute to discuss the impending enanges in the grid. The meetings are intended to provide additiorial insights into the complex problems that are inherent in assuring reliability in the changing industry,
Attachment:
Grid Performance Factors Study cc w/ attachment:
OGC OCA OPA SECY Distribution:
Public BShe n,NRR File Center JM phy,RES AEOD R/F R avio, ACRS
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RAB R/F REmrit, RES CPaperiello, NMSS FCongel DMorrison, RES KRaglin SCollins, NRR DHickman GHolahan, NRR PBaranowsky AThadani, NRR MCunningham, RES
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EJordan, DEDO JMitchell, OEDO OCUMENT NAME: C:\\WP51 \\WPDOCS\\STU DI ES\\CO M MG RID. LTR To receive a copy of this document. Indicate in the box: *C's Copy without attachrnent/ enclosure *E* = Copy with a%chment/e Josure
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LJCallan DATE 030;/97 03/fi/97 03/3/97 Q}/l /97 03/ /97 OFFICIAL RECORD COPY
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