Emergency Diesel Generator Operating Experience, 1981-1983

NUREGICR-4347ORNL/TM-9739

NUREGCR43471/1111/1111111/ /I III /I 1111111 1111/ III III

Emergency Diesel GeneratorOperating Experience, 1981-1983

Prepared by R. E. Battle

Oak Ridge National Laboratory

Prepared forU.S. Nuclear RegulatoryCommission

REPRODUCED BYNATIONAL TECHNICALINFORMATION SERVICE

u.s. DEPARTMENT Of COMMERCESPRINGfiElD. VA. 22161

NOTICE

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NOTICE

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Although the listing that follows represents the majority of documents cited in NRC publications,it is not intended to be exhaustive.

Referenced documents available for inspection and copying for a fee from the NRC Public Document Room include NRC correspondence and internal NRC memoranda; NRC Office of Inspectionand Enforcement bulletins, circulars, information notices, inspection and investigation notices;Licensee Event Reports; vendor reports and correspondence; Commission papers; and applicant andlicensee documents and correspondence.

The follOWing documents in the NUREG series are available for purchase from the GPO SalesProgram: formal NRC staff and contractor reports. NRC-sponsored conference proceedings, andNRC booklets and brochures. Also available are Regulatory Guides, NRC regulations in the Code ofFederal Regulations. and Nuclear Regulatory Commission Issuances,

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- ~ -

NRC FORM 335U.S. NUCLEAR REGULATORY COMMISSION

1. REPORT NUMeER (ASSlgn~dbyDDC)

111.811 NUREG/CR-4347BIBLIOGRAPHIC DATA SHEET ORNL/TM-9739

4. TITLE AND SUBTITLE (Add Volume No.• " appropmJte! 2. (Leave bl/fflk)

Emergency Diesel Generator Operating Experience, 1981-19833 RECIPIENT'S ACCESSION NO.

7. AUTHOR IS) 5. DATE REPORT COMPLETED

R. E. Battle MONTH I YEAR

July 19859. PERFORMING ORGANIZATION NAME AND MAILING ADDRESS (Include Z,p Code! DATE REPORT ISSUED

MONTH I YEAR

Oak Ridge National LaboratoryDecember 1985

Oak Ridge, Tennessee 37831 6. (Leave blank!

8. (Leave blank!

12. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS IInclude Zip Code)

Divisior... of Safety Technology10. PROJECTITASK/WORK UNIT NO.

Office of Nuclear Reactor Regulation 11. FIN NO.

U.S. Nuclear Regulatory CommissionWashington, D.C. 20555 B0744

13.. TYPE OF REPORT IPE RIOD COVE RED (InclUSive dares!

Technical

15. SUPPLEMENTARY NOTES 14. (Leave olank!

ABSTRACT (200 words or less)

The purpose of this report is to update the operating experience of emergency dieselgenerators in nuclear power plants" Previously, similar data for 1976 through 1980 ;werereported in NUREG/CR-2989, "Reliability of Emergency AC Power Systems at Nuclear PowerPlants. " The two data sets are used to show trends of diesel generator performance, aneresponses by nuclear plant licenses to a nuclear regulatory questionnaire is includedfor additional data and comparison with the Licensee Event Report (LER) data collectedfor this report.

The LER database was used to collect diesel generator failures, and the databases fordiesel generator successes were from nuclear plant licensees' responses to NRC question-naires. Estimates of diesel generator failure on demand were calculated from the dieselgenerators test data, from data reported in response to an NRC questionnaire (genericletter 84-15), from diesel generator performance during complete and partial losses ofoff-site power, and from diesel generator performance for safety injection actuationsignals.,

17. KEY WORDS AND DOCUMENT ANALYSIS 17a DESCRIPTORS

Diesel generatorsReliabilityStation blackout

17h. IDENTIFIERSOPEN·ENDED TERMS

18 AVAILABILITY STATEMENT 19 SE CURITY CLASS ITh-s reporl/ 21 NO r~AGESUnclassified

Unlimited 20 SECURITY CLASS ITh" paqel 22 PRICE

Unclassified - .

N8C FORM 335 1118" ,/

ABSTRACT

The purpose of this report is to update the operating experience ofemergency diesel generators in nuclear power plants. Previously,similar data for 1976 through 1980 were reported in NUREG/CR-2989,"Reliability of Emergency AC Power Systems at Nuclear Power Plants."The two data sets are used to show trends of diesel generator performance,and responses by nuclear plant licensees to a nuclear regulatory questionnaire is included for additional data and comparison with theLicensee Event Report (LER) data collected for this report.

The LER database was used to collect diesel generator failures, and thedatabases for diesel generator successes were from nuclear plant licensees'responses to NRC questionnaires. Estimates of diesel generator failureon demand were calculated from the diesel generators test data, from datareported in response to an NRC questionnaire (generic letter 84-15), fromdiesel generator performance during complete and partial losses of off-sitepower, and from diesel generator performance for safety injection actuationsignals.

iii

CONTENTS

LIST OF TABLES

EXECUTIVE SUMMARY

1. INTRODUCTION

2. DATA SOURCES AND DATA QUALITY.

3. ESTIMATES OF FAILURE ON DEMAND

3.1 ESTIMATES BASED ON TEST DATA.3.2 REGRESSION ANALYSIS OF FAILURE ON DEMAND •3.3 DIESEL PERFORMANCE DURING ACTUAL DEMANDS •

4. OBSERVATIONS OF DEMAND DATA.

5. CONCLUSIONS.

REFERENCES

APPENDIX

vii

ix

3

31316

16

24

27

29

Preceding page blank v

LIST OF TABLES

1. Event type definitions

2. Demand data from responses to generic letter 84-15

3. Calculated DG failures per demand by plant

4. Estimates of the mean and median probabilitiesof failure on demand • • • • • • • • . • • . • •

5. Comparison of diesel generator failure data.

6-A. Diesel generator start attempts because of ESFbus undervoltage, 1981-83

2

4

10

13

14

17

6-B.

7-A.

7-B.

Diesel generator failures occurring duringthe events listed in Table 6-A • • • •

Diesel generator start attempts caused by asafety injection actuation signal, 1981-83

Diesel generator failure occurring during theevents listed in Table 7-A •.••••.

19

20

22

8. Diesel generator failures per demand based onactual demands, 1981-83 • .••.••

9. Test intervals for four diesel generators

Preceding page blank vii

22

23

EXECUTIVE SUMMARY

The purpose of this report is to update the operating experience ofemergency diesel generators in nuclear power plants. Previously,similar data for 1976 through 1980 were reported in NURE.G/CR-2989,"Reliabili ty of Emergency AC Power Systems at Nuclear Power Plants."The two data sets are used to show trends of diesel generatorperformance, and responses by nuclear plant licensees to a nuclearregulatory questionnaire is included for additional data and comparisonwith the Licensee Event Report (LER) data collected for this report.

The LER database was used to collect diesel generator failures, and thedatabases for diesel generator successes were from nuclear plantlicensees' responses to NRC questionnaires. Failure definitions arebased on whether an emergency ac power system would supply ac powerduring a loss of off-site power not concurrent with a loss of coolantaccident. The success and failure data are summarized in tables, andthe strengths and weaknesses of the data are discussed. The mostsignificant weakness of the LER data is that the LER reporting systemwas not organized for reliability studies. The strength of the reliability calculations is that the diesel success data are reported in moredetail than has been available in many other studies. Diesel surveillance test data were tabulated for each diesel generator at most operating nuclear power plants. The average number of surveillance testsperformed each year varied significantly. The average diesel testfrequency varied from monthly to once every 3 days. Excessive testingmay lead to wear out of components, and periods of frequent testingfollowed by periods of infrequent testing may have an effect onreliability estimates. This report examines the potential effects oftesting schedules on equipment reliability and on the estimates ofequipment reliability.

Estimates of diesel generator failure on demand were calculated from thediesel generators test data, from data reported in response to an NRCquestionnaire (generic letter 84-15), from diesel generator performanceduring complete and partial losses of off-site power, and from dieselgenerator performance for safety injection actuation signals. Thediesel generator surveillance test data and LER failure data indicatethat diesel reliability has been improving from 1976 through 1983. However, the number of diesel failures during losses of off-site power in1981 through 1983 is greater than would be expected based on thesurveillance test data.

Preceding page blank ix

1. INTRODUCTION

This report reviews diesel generator operational experience for thethree years 1981 through 1983 and estimates the probability of a dieselgenerator failing on demand. The results from the 1981 through 1983data are compared with previous estimates of the probability of failureon demand and with the estimates reported by nuclear plant licensees inresponse to the Nuclear Regulatory Commission (NRC) generic letter84-15. 1

The probability of failure on demand may be used to estimate the reliability of emergency ac power systems, but based on the data reported inthe responses to generic letter 84-15, using the actual number ofdemands to estimate system reliability may result in inaccuracies. Thisreport discusses these inaccuracies.

2. DATA SOURCES AND DATA QUALITY

The diesel generator failures were identified by reviewing LicenseeEvent Reports (LERs) for events that occurred in 1981, 1982, or 1983.The events were categorized as primary or secondary failures to start orrun, as autostart failures, or as nonfailures. The definitions of thesecategories are in Table 1. For this study, primary and secondary failures to start were used to estimate diesel generator probability of failure on demand. The primary, secondary, and autostart failures aretabulated in the Appendix.

Events for which a diesel failed to supply power to a Class 1E bus wereusually considered failures. Exceptions were trips caused by reversepower or by manual trip of the diesel because of a water leak. Eventsinvolving fuel oil leaks were difficult to categorize. An operator maystop the diesel to avoid a possible fire caused by the leak, however;the leak may have been small enough that in an emergency an operatorcould take adequate fire protection without shutting down the diesel.For most fuel oil leaks an accurate determination could not be made.Some LER descriptions were not adequate to determine whether the eventwould have been a failure during a loss of off-site power; these eventswere categorized based on our best judgment.

The failure data reported in the licensee responses to the NRC genericletter 84-15 were not included with the LER failure data for two reasons.First, the time periods were different for the two sets of failure data.The LER data were for 1981 through 1983, and the generic letter datacovered periods of time prior to August or September 1984 in which 100demands for a diesel generator were made. Second, most of the responsesto the generic letter did not describe the diesel generator failuresadequately for us to categorize them.

The two data sets contain different numbers of failures. These differences in data occur because failures included in the LER data may not beincluded in the generic letter data and vice versa. A more detailedcomparison of the two data sets may be useful to determine why some failures included in the LER data were not considered failures by the

2

Table 1. Event type definitions

Event type Definition

Primary failure to start A diesel generator fails tostart on a test or actual demandbecause of an "end-of-life" orintrinsic component failure thatprevents the diesel from supplying power to the emergency buson a loss of off-site power

Primary failure to run Similar to a "primary failure tostart" except that the dieselgenerator must reach rated speedand voltage, supply the desiredload, and reach equilibriumconditions prior to the failure

Secondary failure to start Similar to a "primary failure tostart" except that this failureis caused by an external influence and the failed component isnot accountable for the failure

Secondary failure to run Similar to a "primary failure torun" except that this failure iscaused by an external influence

Autostart failure A diesel generator fails tostart on test or actual demand,but it is capable of beingstarted manually immediatelyafter it does not startautomatically

Nonfailure A diesel generator is capable ofsupplying power to the emergencybus on a loss of off-site power,but it is declared inoperableand removed from service forscheduled or unscheduled maintenance. This category includesother LERs that are not primary,secondary, or autostart failures

3

licensee and to determine whether some of the failures reported in thegeneric letter responses were not reported in the LER system.

Failure on demand was estimated using the LER failure data and thedemand data reported in the responses to the NRC generic letter 84-15 orin NUREG/CR-2989. 2 The preferred demand data sources were the responsesto the NRC generic letter, the second source was the plant-specificdemand data reported in NUREG/CR-2989, and the third source was theindustry average number of demands calculated from the data inNUREG/CR-2989. The demand data were used to calculate the averagenumber of demands per diesel generator per year which was used in turnto calculate the total number of demands that occurred for all dieselsat a plant for the years 1981 through 1983. If the response to genericletter 84-15 did not have enough information to calculate the number ofdemands per year, then the data in NUREG/CR-2989 were used. The averagenumber of demands per diesel generator per year is in Table 2. Additional observations of the demand data are in Sect. 4.

3. ESTIMATES OF FAILURE ON DEMAND

The probability of diesel failure on demand was estimated based ondiesel successes and failures during tests; the diesel performanceduring actual demands--safety injection signals and losses of off-sitepower--was calculated for comparison. Estimates of the probability offailure on demand were calculated from LER data collected for this studyand from data provided in the responses to generic letter 84-15.

3.1 ESTIMATES BASED ON TEST DATA

Estimates of the probability of failure on demand were calculated formost of the operating U.S. nuclear power plants for the years 1981through 1983. The probability of failure per demand was estimated bygrouping all of the diesels at a plant and dividing the number of dieselfailures at a plant by the estimate of the total number of demands ofthe emergency diesels at the plant. This method was used for the LERdata and the generic letter data rather than using the data for eachdiesel generator. Estimates of the probabilities of failure on demandfor most of the operating plants are listed in Table 3. The median andmean estimates of the probability of failure on demand are based onthese data and are reported in Table 4.

The histogram (Fig. 1) comparing the two data sets uses percentagesbecause the numbers of plants in the two data sets are different. Themean estimate from the LER data is compared to other estimates inTable 5, but it is important to note that the methods used to calculatethe probability of failure on demand were not the same in each case.The method used in NUREG/CR-2989 was to calculate a failure rate, A, bydividing the number of failures by the period of time the diesel werebeing examined--5 years for most plants; the probability of failure ondemand was then calculated using Eq. (1).

~

Table 2. Demand data from responses to generic letter 84-15

-------------------------

Plant Test period dates Number of Demandsname DG Beginning End demands per year Comments

Arkansas A -- 07/84 100 -- The date of the first demand was not reportedNuclear One 1 B -- 07/84 100

Arkansas A -- 07/84 100 -- The date of the first demand was not reportedNuclear One 2 B -- 07/84 100

Arnold IG-31 02/81 10/84 100 27IG-21 09/80 10/84 100 24

Beaver 1 09/78 08/84 100 17Valley 1 2 05/78 08/84 100 16

Big Rock 1 08/80 09/84 455 111Point

Browns Ferry 1A -- -- -- -- The time period was not reported .t::"

1, 2, 3 1B1C1D3A3B3C3D

Brunswick 1, 2 1 -- 07/84 100 -- The start date was not reported2 -- 07/84 1003 -- 07/84 1004 -- 07/84 100

Calvert Cliffs 11 08/83 06/84 100 1201, 2 12 09/83 06/84 100 150

21 07/83 06/84 100 109

Connecticut 2A -- -- -- -- Da ta una va ilableYankee 2B

Donald C. Cook 1AB 04/80 10/84 100 221, 2 1CD 06/79 10/84 100 19

2AB 03/81 10/84 100 282CD 08/81 10/84 100 32

".

Cooper

Crystal River 3

Davis-Besse

Diablo Canyon 1

Dresden 2, 3

Joseph M.Farley 1, 2

FitzPatrick

Fort Calhoun

Fort St. Vrain

R. E. Ginna

Grand Gulf

Edwin I.Hatch 1, 2

12

3A3B

12

1-11-2

'1-3

22/33

1-2AlB2BlC2C

ACBD

12

AB

1A1B

111213

lAlClB2A2C

04/8107/81

12/8012/8104/81

01/7801/78

OLOLOL

08/8408/84

09/8409/8409/84

09/8409/8409/8409/8409/84

12/8412/84

09/8409/84

09/8409/8409/84

100100

100100

100100100

100100100100100

9693

100100

936978

3032

273629

1413

403033

The time period for 100 demands was notreported

The time period for 100 demands was notreported

Demand data were not reported. DG 1-2 isa swing diesel for Units 1 and 2

The beginning date for the demand datawas not reported

Data unava ilable

The letter date was used as the ending date

Data unavailable

The beginning date was not reported

The beginning date was the date of receiptof an operating license (OL) 6/82

Beginning and ending dates were not reported

Ul

Table 2 (continued)

Plantname DG

Test period datesBeginning End

Number ofdemands

Demandsper year Comments

~

Indian Point 2

Indian Point 3

Kewaunee

LaCrosse

LaSalle

McGuire 1, 2

Maine Yankee

Millstone 1, 2

l~onticello

Nine Mile Point

212223

313233

lAlB

lAlB

olA2AlB2B

lAlB2A2B

lAlB

DG12U13U

1112

102103

03/8003/8003/80

0717706177

04/8204/8204/8204/8212/83

OLOLOLOL

11/8411/8411/84

08/8407/84

10/8410/8410/8410/8410/84

10/8410/8410/8410/84

10/8410/84

10/8410/84

301270280

551542

5151385610

70642327

100100

675961

7877

2020152212

19171517

1717

The ending date of the test period wasthe date of the letter response to genericletter 84-15

Detailed demand data were not reported

The beginning and ending dates were notreported

The ending date is the date of the letterresponse to generic letter 84-15. Unit 1fuel load 4/82, 4 diesels. Unit 2 fuel load12/83, 1 diesel added

The beginning dates are the dates of theoperating licenses-Unit 1 (2/81) and Unit 2(3/83), and the ending date is the date of theletter response to generic letter 84-15

The beginning and ending dates were notreported

Da ta una va ilable

The utility reported 100 tests performedin approximately 6 years. Letterresponse was dated 10/84

Beginning and ending dates were notreported.

0'\

".

North Anna 1, 2 1H -- 02/85 100 -- The beginning dates were not reported1J -- 02/85 1002H -- 02/85 1002J -- 02/85 100

Oconee 1, 2, 3 Hydro units are used instead of dieselgenerators at Oconee

Oyster Creek 1 08/82 09/84 101 482 04/82 09/84 100 41

Palisades 1-1 04/77 07/84 100 141-2 06/76 07/84 100 12

Peach Bottom E1 02/82 08/84 186 74 Demand information was reported for a2, 3 E2 02/82 08/84 191 52 2.5-year period

E3 02/82 08/84 178 71E4 02/82 08/1<4 164 66

Pilgrim A 09/81 06/84 100 36B 12/81 06/84 100 40

Point Beach 1, 2 3D 03/82 09/84 100 40 -.;j

4D 02/82 09/84 100 39

Prairie Island 1 -- -- -- -- Data unavailable1, 2 2

Quad Cities 1 -- -- -- -- Data unavailable1, 2 1/2

2

Rancho Seco A 12/78 07/84 108 19B 07/78 07/84 109 18

H. B. Robinson A 09/82 08/84 100 52B 09/82 08/84 100 52

St. Lucie 1, 2 1A -- -- ~- -- Dates were not reported. The response1B -- -- -- -- was dated 10/842A2B

~

Table 2 (continued)

Plant Test period dates Number of Demandsname DG Beginning End demands per year Comments

Salem 1, 2 lA -- 43 mo 63 18 The number of months of the test period waslB -- 44 mo 57 16 reported rather than beginning and endinglC -- 41 mo 69 20 dates2A .... No 35 mo 100 342B -- 33 mo 100 362C -- 35 mo 100 34

San Onofre 1 1 04/77 04/84 372 532 04/77 04/84 387 55

San Onofre 2, 3 2G002 07/82 08/84 100 40 Unit 2 operating license was 2/82, and the2G003 02/82 08/84 92 37 Unit 3 operating license was 11/823G002 12/82 08/84 88 533G003 12/82 08/84 82 49

Sequoyah 1, 2 lA-A 03/80 05/84 132 32 Unit 1 operating license was 10/80 and 00

2A-A 03/80 05/84 128 31 Unit 2 operating license was 6/81lB-B 03/80 05/84 147 352B-B 03/80 05/84 132 32

Virgil C. Summer A OL 09/84 36 17 For the test period the operating licenseB OL 09/84 41 20 date and the date of the letter response to

generic letter 84-15 were used. (OL 8/82)

Surry 1,2 1 -- -- ..... ""- _.:.:.. Data unavailable23

Susquehanna 1 A OL 09/84 57 26 The operating license was issued 7182B OL 09/84 49 23C OL 09/84 53 24D OL 09/84 50 23

Three Mile lA 02/79 07/84 100 18Island 1 lB 11/79 07/84 100 21

Trojan West 02/79 10/84 102 18East 10/79 10/84 103 20

".

Turkey Point A 10/84 04/83 100 673, 4 B 10/84 04/83 100 67

Vermont Yankee A 01/81 09/84 100 29B 01/81 09/84 100 24

Yankee Rowe 1 10179 08/84 100 212 10179 08/84 100 21

.3 10179 08/84 100 21

Zion 1, 2 1A 10/82 07/84 100 571B 12/82 07/84 100 630 05/83 07/84 100 862A 11/82 07/84 100 602B 09/82 07/84 100 54

-------"-_._--------------- --------

~

10

Table 3. Calculated DG failures per demand by plant

Data based onData based on LERs generic letter

Plant name 1981-1983 84-15

D* Ft F/Df D* Ft F/Df

Arkansas Nuclear 1, 2 208** 5 0.024 400 8 0.020Arnold 153 0 0 200 3 0.015Beaver Valley 1 99 2 0.020 200 29 0.145Big Rock Point 333 2 0.006 455 10 0.022

Browns Ferry 1, 2, 3 744 tt 10 0.013 800 11 0.014Brunswick 1, 2 144 14 0.097 400 16 0.040Calvert Cliffs 1, 2 1137 13 0.011 300 0 0Connecticut Yankee 186tt 2 0.011 0.01

D. C. Cook 1, 2 303 7 0.023 400 9 0.023Cooper 160** 8 0.050 200 15 0.075Crystal River 3 186 7 0.038 200 9 0.045Davis-Besse 234** 2 0.009 200 5 0.025

Dresden 2, 3 276 6 0.022 300 13 0.043J. M. Farley 1, 2 1050** 12 0.011 500 7 0.014J. A. FitzPatrick 249** 1 0.004 200 1 0.005Fort Calhoun 81 1 0.012 189 17 0.090

Fort St. Vrain 186tt 4 0.022R. E. Ginna 169** 0 0 200 9 0.045Grand Gulf 154 17 0.110 240 5 0.021E. 1. Hatch 1, 2 837** 12 0.014 500 3 0.006

Indian Point 2 561 0 0 851 1 0.001Indian Point 3 150** 0 0 300 0 0Kewaunee 465 2 0.002 200 11 0.060LaCrosse 256** 2 0.008 200 3 0.015

LaSalle 146 1 0.007 206 1 0.005McGuire 126 4 0.032 184 7 0.038Maine Yankee 97** 2 0.021 200 14 0.070Millstone 1, 2 641** 5 0.008

Monticello 102 1 0.010 200 0 0Nine Mile Point 77** 1 0.013 200 2 0.010North Anna 1, 2 384** 5 0.013 400 6 0.015Oyster Creek 267 2 0.007 200 2 0.010

Palisades 78 4 0.051 200 7 0.035Peach Bottom 1, 2 789 2 0.003 400 1 0.003Pilgrim 228 2 0.009 200 8 0.040Point Beach 1, 2 237 1 0.004 200 2 0.010

11

Table 3 (continued)

Plant nameData based on

84.0.15

D* D*

Prairie Island 1, 2Quad Ci ties 1, 2Rancho SecoH. B. Robinson

st. Lucie 1, 2Salem 1, 2San Onofre 1, 2, 3Sequoyah 1, 2

v. C. SummerSurr y 1, 2SusquehannaTrojan

Turkey Point 3, 4Vermon t YankeeYankee RoweZion 1, 2

264**253**111104

227tt474575359

49157**136117

402159189960

o412

389

11

311o

4219

o0.0160.0090.019

0.0130.0170.0160.031

0.0610.0060.007o

0.0100.0130.0050.009

200200

80489

1121400

77300209205

200200300500

122

11416

3

144

19

341

12

0.0600.010

0.0130.0290.0140.008

0.0130.0130.0190.093

0.0150.0200.0030.024

*D: Demands for all diesels at a plant.

+tF: Failures of all diesels at a plant.F/D: Failures per demand.

**Number of demands calculated from plant.o.specific data reported inNUREG/CR.o.2989.

ttIndustry average of 31 d/DG calculated from NUREG/CR.o.2989.

ORNL-DWG 85C-14020

30 I 7~

- GENERIC LETTER 84-1525 •C')

w

I I1III11111 ~-oJa:l n LER DATA« 1""11111 1;1

t-Z 20-ent-z«...Ja.. 15u.0

WAlil,'IIIIW~IIIIIIII~111111111 ~ I I\)

w(9

« 10t-ZW()

a:wa.. 5

o

~

.005 .01 .015 .02 .025 .03 .035 .04 .045 .05

FAILURES PER DEMAND

Fig. 1. Diesel generator failure on demand calculated from the data in Table 3.

>.05

13

Table 4. Estimates of the mean and median probabilities offailure on demand

StandardMean deviation Median

LER data 0.017 0.024 0.011

Generic letter 84-15 0.027 0.029 0.019data

P A T/2 (1)

where

p probability of failure on demand,A failure rate,T time between scheduled tests.

This method of estimating the probability of failure on demand was usedbecause many plants group many diesel generator tests throughout a year.This observation on time intervals between demands is discussed furtherin Sect. 4.

For plants with many more demands than would result from the scheduledtests, the probability of failure on demand calculated from Eq. (1)would be a larger esti~ate than using the number of failures divided bythe number of demands.

3.2 REGRESSION ANALYSIS OF FAILURE ON DEMAND

A regression analysis was performed to examine the trend of theprobability of failure on demand from 1976 through 1983 based on LERdata in ref. 2 and in this study. Yearly means were calculated for thenuclear industry, and these means and a least-squares fit were plottedin Fig. 2. The equation of the least-squares curve is

FlO = 0.026 - 0.0015 • (YR - 1976) (2)

where FlO = failures per demand and YR year.

The standard error of the intercept is 0.003 and the standard error ofthe slope is 0.0006. Based on a t-test, the hypothesis that the slopeof the curve is zero would be rejected at 98% confidence bounds. Basedon these data, diesel generator performance has been improving since1976.

14

Table 5. Comparison of diesel generator failure data

Source

Larsson and Wallin3(Swedish NuclearPower Inspectorate)

A. E. Green 4(United Kingdom)

NUREG/CR-13625

Crooks and Vissing6

WASH-1400 7

NRC Internal Reviewby Power SystemsBranch (unpublished)

P. W. Baranowsky(NRC) (unpublished)

R. F. Scholl (NRC)(unpublished)

IEEE Std. 500-19778

NUREG/CR-2989

This study

Failure mode

StartRun

StartRun

Start (weekly test)Start (monthly test)Run (weekly test)Run (monthly test)

Start

StartRun

StartRun

Start

Start

StartRun

StartRun

Start

Failure probability

3 x 1O-3/demand6 x 10-4Ih

1 x 10-2/demand2 x 10-5/h

1 x 10-2/demand4 x 10-2/demand6 x 10-3 /h3 x 1O-2 /h

2.8 x 10-2/demand

3 x 10-2/demand3 x 10-3 /h

1.9 x 10-2/demand2.8 x 10-2/demand

2 x 10-2/demand

1.4 x 10-2/demand

8 x 10-3/demand1.3 x 1O-4/h

2.5 x 10-2/demand2.3 x 10-3/h

1.7 x 10-2/demand*

*Mean estimate based on LER failure data.

15

OR N l-DWG 85C-12051

o. 04 ---......---~----r---~----.,r----..,.-------,

• YEARLY MEAN

- LEAST-SQUARES FITOF YEARLY MEANS

0.03

czc21,&1cg:1,&1Q.

1,&1a::::»...I

CIL

0.02

•

0.01

83828179 80

YEAR

7877

0.00 L.-__..L.-__.....L...__--l...__---L L..-.__..I.-__....

78

Fig. 2. Least~squares curve fit for yearly means of dieselgenerator failure on demand.

16

3.3 DIESEL PERFORMANCE DURING ACTUAL DEMANDS

The actual demands--diesel starts for loss of ac power or for a safetyinjection signal--provide additional information on diesel generatorreliability. Diesel generator starts and failures for undervoltage onan emergency safety system (ESF) bus and for safety injection signalswere calculated. The undervoltage events involving diesel generatorstarts are listed in Table 6-A, and the diesel generator failures forthose events are listed in Table 6-B. The safety injection eventsinvolving a diesel generator start are listed in Table 7-A, and thediese~ generator failures for those events are listed in Table 7-B.

Calculations of failures per demand for the actual demands are presentedin Table 8. The calculated value of failure per demand for bus undervoltage is much larger than the failure per demand estimate based ondiesel generator testing data in Table 4, but the repair times for theevents at Brunswick 2 and Crystal River 3 listed in Table 6-B may havebeen much less than the estimated median repair time of 8 h reported inref. 2, and the repair time for the event at Fort St. Vrain was reportedto be 25 min.

4. OBSERVATIONS OF DEMAND DATA

Most of the nuclear plant licensees responding to generic letter 84-15reported the number of demands and the period of time during which thedemands occurred. For those that reported both the number of demandsand the time period involved, estimates of the number of demands peryear were calculated. These data are reported in Table 2. Estimates ofthe number of demands per year were needed to calculate a probability offailure per demand for the failure data covering the period from 1981through 1983.

This section includes some additional observations about the data complied from the responses to generic letter 84-15. A few of the plantsresponding to the generic letter included the dates of each dieselgenerator demand. The number of days between each test was selectedfrom generic letter 84-15 for four diesel generators as shown in Table 9.The sample data show that many tests are performed on a regular scheduleevery month, two weeks, or few days; however the data indicate that manytests appear to be unscheduled. For example, the Trojan diesel (inTable 9) was tested every 4 weeks or more for 38% (28 tests) of thetests, but 19% (14 tests) had a test interval of three days or fewer.The remainder of the test intervals were between 3 and 27 days. Thereliability of this diesel may be overestimated if the number of failures is divided by the number of demands because test intervals muchshorter than the regularly scheduled tests result in operation of equipment known to be in good working order. The contribution to the probability of failure by human error and other time-related causes of failure would be reduced, and such a calculated estimate of the probabilityof failure would be lower than it actually is. However, the error inestimating demand may not be significant. If the diesel at Trojan hadfailed once (which was not the case) then an estimate of its probabilityof failure on demand would be 1/73, which equals 0.014. If the 14

17

Table 6-A. Diesel generator start attempts because of ESF busundervoltage, 1981-83

-------Plant LER No. of DGsname No. Date Installed Demanded Comments

Beaver Valley 1 83-2 1/7/83 2 Partial loss ofoff-site power

Beaver Valley 1 83-16 5/28/83 2 Partial loss ofoff-site power

Brunswick 2 82-123 10/10/83 4 Loss of power to4160-v bus E-3;DG 3 breakerfailed to close

Brunswick 1.2 83-23 4/26/83 4 2 Loss of off-sitepower to Unit 1

Crystal River 3 81-33 6/16/81 2 2 DG B failed tostart

J. M. Farley 2 10/8/83 5 4 Loss of off-sitepower to Unit 28

Fort St. Vrain 83-18 5/17 /83 2 2 One DG wasunavailable andone DG failed tostart

Ginna 81-7 4/18/81 2 2

Indian Point 2,3 10/4/83 6 6

LaCrosse 81-2 2/1/81 2 2

LaCrosse 81-4 3/9/81 2 2

LaCrosse 81-14 12/23/81 2 2

Millstone 2 1/2/81 2 2 Partial loss ofoff-site power.One diesel failed 9

Monticello 81-9 4/27/81 2 2

Nine Mile Point 82-4 2/7 /82 2 2

18

Table 6-A (Continued)

Plant LER No. of DGsname No. Date Installed Demanded Comments

North Anna 1 81-20 4/2/81 2 Power to Bus lHlfailed

North Anna 1,2 7/3/81 4 2 Partial powerfailure in bothunits9

Oyster Creek 11/14/83 2 2 Complete loss ofoff-site power9

Pilgrim 82-51 10/12/82 2 2

Pilgrim 2/13/83 2 2 Partial loss ofoff-site power8

Quad Cities 1,2 82-12 6/22/82 3 2 DG 1/2 tripped

St. Lucie 1 82-37 8/16/82 2 Power to Bus lA3failed

St. Lucie 82-40 9/2/82 2 2

St. Lucie 82-41 917 /82 2 2

Summer 83-111 9/11/83 2 DG A started

19

Table 6-B. Diesel generator failures occurring duringthe events listed in Table 6-A

LER FailureFailures No. Date type Comments

Brunswick 2 82-123 10/10/83 PS During switchingoperations an ESF bus wasdeenergized; the DGstarted but its outputbreaker failed to close

Crystal River 3 81-33 6/16/81 SS DG B failed to functionbecause of a poorlyadjusted timing relay

Fort St. Vrain 83-18 5/17/83 AS The plant was shut down,and DG 1A was down formaintenance. DG 1B wasoperating parallel to anESF bus when off-sitepower failed. DG 1Btripped but was restoredin 25 min

Millstone 2 81-5 1/2/81 SS A dc bus was deenergizedand a partial loss ofoff-site power occurred.DG B tripped because of awater leak that sprayedthe governor9

Quad Cities 1 82-12 6/22/82 SS Unit 2 lost off-sitepower and DG 1/2 trippedon underexcitation when aservice water pumpstarted

20

Table 7-A. Diesel generator start attemptscaused by a safety injection actuation

signal, 1981-83

DGs startedPlant Date LER No. by SI

Beaver Valley 1 2/12/83 83-5 2Browns Ferry 2 7/20/81 81-40 4Brunswick 1 2/11/82 82-23 4

Calvert Cliffs 1 11/30/83 83-65 3Calvert Cliffs 2 2/3/83 83-7 3FitzPatrick 1/17/81 81-10 2

FitzPatrick 9/14/83 83-36 2Ginna 1/25/82 82-3 2Grand Gulf 1 7/18/83 83-84 3

83-101

Grand Gulf 8/27/83 83-129 3Grand Gulf 11/22/83 83-187 3LaSalle 1 7/18/83 83-85 3

83-87

McGuire 1 3/30/81 81-37 2McGuire 1 4/29/81 81-74 1McGuire 1 9/14/81 81-151 2

McGuire 1 12/24/81 81-193 2McGuire 1 1/11/82 82-7 2North Anna 3/29/81 81-18 2

North Anna 7/6/81 81-55 2North Anna 12/4/82 82-83 2North Anna 12/5/82 82-85 2

North Anna 1 1217/82 82-88 2North Anna 1 5/23/83 83-33 2North Anna 2 7/3/81 81-55 2

North Anna 2 8/8/81 81-60 1North Anna 2 8/10/81 81-62 1North Anna 2 10/3/81 81-76 2

North Anna 2 4/2/83 83-29 1North Anna 2 10/17/83 83-71 2Palisades 12/4/81 82-4 2

21

Table 7-A (continued)

Plant Date LER No.DGs started

by SI

Peach Bottom 2 10/24/82 82-36 4Robinson 2 1/29/81 81-5 2Robinson 2 1/29/81 81-6 2

St. Lucie 11/26/82 82-62 2Salem 1 10/29/81 81-107 3Salem 1 11/6/81 81-97 3

Salem 1 11/6/81 81-110 3Salem 1 1/30/83 83-9 3Salem 2 4/23/81 81-9 3

Salem 2 4/23/81 81-45 3Salem 2 6/3/81 81-82a 3Salem 2 6/3/81 81-32 3

Salem 2 6/27/81 81-51 3Salem 2 6/27/81 81-82b 3Salem 2 3/7 /82 82-19 1

Salem 2 8/12/83 83-53 3San Onofre 9/3/81 81-20 2San Onofre 9/25/81 81-23 2

San Onofre 1 11/10/83 83-5 2San Onofre 2 11/9/82 82-136 2

82-138San Onofre 3 12/17/82 82-6 2

Sequoyah 2 1/21/82 82-15 2Surry 1 1/6/82 82-1 3Surry 1 2/8/82 82-27 3

Surry 1 3/25/82 82-40 3Surry 1 4/13/82 82-45 3Surry 2 10/10/82 82-63 3

Turkey Point 4 9/6/82 82-13 2Zion 1 5/28/81 81-8 3

81-29Zion 7/6/82 82-26 3

Zion 1 6/13/83 83-17 3Zion 2 5/7 /81 81-8 _3

TOTAL 151

22

Table 7-8. Diesel generator failures occurring during the eventslisted in Table 7-A

Plant

Calvert Cliffs 2

Grand Gulf 1

LER No. Date

2/3/83

8/27/83

Failuretype

PS

SS

Comments

DG 2 failed to start,but no cause of thefailure was found

The plant was shutdown when and an inadvertent S1 occurred.The DG tr ippedbecause servicewater valves wereclosed for maintenance

Table 8. Diesel generator failures per demand basedon actual demands, 1981-83

Primary orNo. of secondary failure Autostart failures

Cause demands No. Failure/demand No. Failure/demand

Bus undervoltage 50 4 0.080 0.020

Safety injection 151 2 0.013 0 0actuation signal

Both causes 201 5 0.025 2 0.010

23

Table 9. Test intervals for four diesel generators

Peach Bottom Dresden Kewaunee TrojanTest DG 4 DG 2/3 DG 1B DG 7/East

interval No. of No. of No. of No. of(d) tests %* tests %* tests %* tests %*

0-3 17 18 38 39 117 50 14 19

3-6 12 12 14 15 38 16 6 8

6-9 15 15 5 5 35 15 4 6

9-12 3 3 6 6 17 8 5 7

12-15 50 51 5 5 6 3 2 2

15-18 0 0 3 3 3 4 6

18-21 0 0 13 14 8 3 3 4

21-24 9 4 3 4

24-27 0 0 2 2 0 0 4 6

27-30 0 0 3 3 0 0 25 34

30-33 0 0 6 6 0 0 0 0

>33 0 0 0 0 3 4

TOTAL 98 100 97 100 234 100 73 100

*Percentage of total starts of each DG.

24

demands with fewer than 3-day test intervals were not counted becausetime-related failures causes would not occur, then an estimate of failure on demand would be 1/59 which equals 0.017. Because of uncertainties in the data--such as determining whether an event should be countedas a failure--this error in an estimate is not significant.

Two of the four diesels listed in Table 9 perform more than 30% of thetests on 3-day test intervals. Frequent testing such as this may becontributing to diesel wear out as suggested by many in the nuclearindustry. However, Kewaunee tests frequently throughout the year, andit~ very low probability of failure on demand does not indicate wearout.

Another observation is that it takes some plants less than a year toperform 100 demands, while other plants take approximately 6 years.This difference in count may be partially a result of the definition ofa demand as defined in the NRC Regulatory Guide 1.108. A valid teststart is defined in Reg. Guide 1.108, Section 2.e (3) as follows:"Successful starts, including those initiated by bona fide signals,followed by successful loading (sequential or manual) to at least 50% ofcontinuous rating and continued operation for at least one hour shouldbe considered valid successful tests." Based on this definition, if adiesel is not loaded, the startup alone would not be counted as asuccessful start.

If this definition is used, some useful diesel generator data may beoverlooked. A successful start of a diesel is useful data because manyfailures occur during starting of a diesel. If a diesel is successfullystarted but not loaded, a piece of information on a start would be available even though a complete test would not be performed.

A summary of some of the observations related to diesel test intervaland the method of counting diesel test starts for calculating a probability of failure on demand follows. More than half of the tests forsome diesel generators are performed for other purposes than theperiodic tests required by technical specifications. There are shortintervals between many of these tests. The effect of having many testswith significantly different intervals between tests may be to slightlyoverestimate reliability. However, to determine the effect of differingtest intervals requires further investigation. A second observation isthat the method of counting start attempts based on NRC Regulatory Guide1.108 may result in underestimating diesel generator reliability becausemany starts are excluded by a definition in Regulatory Guide 1.108.

5. CONCLUSIONS

The point estimate of the median probability of a diesel generator failing on demand based on LER failure data for 1981 through 1983 is lessthan point estimates in many previous studies. A regression analysisindicates that diesel generator performance has been improving since1976. Estimates of probability of failure on demand calculated in thisstudy may be a low estimate because of the number of demands used tocalculate the probability of failure on demand. All tests other than

25

tests for troubleshooting were counted regardless of the test intervals.Many previous studies have assumed fewer demands or, as inNUREG/CR-2989, did not use the actual demand data to estimate theprobability of a diesel failure.

Some plants reported in response to generic letter 84-15 that 100demands were completed in less than a year while others reportedapproximately 6 years to complete 100 demands. This significantdifference may be the result of the definition of a valid demand. Tomake certain that all of the useful data--demands and failures--areused, the definition of a valid failure should be modified from that inRegulatory Guide 1.108 to include tests for which the diesel is notloaded to more than 50% for 1 h. If the difference in the number oftests is not a result of the definition of a valid test, but is causedby different approaches of testing diesels, the two methods should beexamined in more detail to determine whether there may be an effect ondiesel reliability because of the different methods.

REFERENCES

1. NRC Generic Letter 84-15, "Proposed Staff Actions to Improve andMaintain Diesel Generator Reliability," July 2, 1984.

2. R. E. Battle and D. J. Campbell, "Reliability of Emergency ACPower Systems at Nuclear Power Plants," NUREG/CR-2989,July 1983.

3. Y. Larsson and L. Wallin, "Reliability Analysis of the AuxiliaryPower Supply in Forsmark 3," Specialists Meeting on Power SupplyArrangements in Nuclear Power Plants, pp. 136-44, Stockholm, Sweden,September 1978.

4. A. E. Green, "The Reliability Assessment of Emergency ElectricalSupplies," Proc. 1975 Annual Reliability and MaintainabilitySymposium, pp. 470-75, Washington, D.C., January 1975.

5. J. P. Polaski and W. H. Sullivan, "Data Summaries of Licensee EventReports of Diesel Generators at U.S. Commercial Nuclear PowerPlants," NUREG/CR-1362, p. 51, March 1980.

6. J. L. Crooks and G. S. Vissing, "Diesel Generator OperatingExperience at Nuclear Power Plants," p. 21, U.S. Atomic EnergyCommission, 00E-ES-002, June 1974.

7. U.S. Nuclear Regulatory Commission, "Reactor Safety Study: AnAssessment of Accident Risks in U.S. Commercial Nuclear PowerPlants," NUREG-75/014 (WASH-1400), October 1975.

8. H. Wyckoff, "Losses of Off-site Power at Nuclear Power Plants, AllYears Through 1983," NSAC-80, July 1984.

9. R. E. Battle, "Collection and Evaluation of Complete and PartialLosses of Off-site Power at Nuclear Power Plants," NUREG/CR-3992,February 1985.

Preceding page blank 27

APPENDIX

PRIMARY, SECONDARY, AND AUTOSTART FAILURES

Preceding page blank

30

LNIT: Arkalsas NLClear 1, 2

t£R El.ent DaNn- El.ent type/No. date Ili tirre cmm:mts Slbsystem Cause

82-15 07/13/82 1 Primary failure to run Fuel Fuel oil day tank high-levellimit switch failed. Hefuel oil transfer p.1!1p over-filled the day tank spillingfuel. The room filled withsmoke, rut there was no qJenfire. The reactor was at9.9%

82-5 fJ2!27/82 2 Primary failure to start Turbocharger The turbocharger failedald caused a diesel trip.The reactor was at 84%

81-12 lE/21/8l B Autostart failure C01trol The taehorreter frequencyrelay failed which causedal overcrank relay to tirreout. The diesel was notautomatically connected tothe bus. A reactor trip aldslow bus transfer startedthe diesel

81-25 llS/30/8l 2 Secondary failure to start/ Ergine Diesel exhaust fires occurredqJerating procedures twice I'lhen oil-€Oaked insu-

8l-25a 07/27/81 2 Secondary failure to start/ Ergine lation caught fire. Op3ra-cperating procedures ting procedures have been

modified to avoid this prob-lem. The reactor was at 0%

81-7 ~/27/8l B Secondary failure to start/ C01trol The diesel tripped becauseNJlllin error a blocking oovice was left

in the loss of excitationrelay. The device was leftin the relay after al18-month surveillance. Thereactor was at 100%

LNIT: Beaver Valley 1

LERNo.

DOtIntine

31

E\ent type/ClJll'Irents SLbsystem Cause

82-36

81-11

W/19/82

03/09/81

2

2

Sa::ondary failure to run

Primary failure to start

Cooling water

Governora1d turbo

charger

Heat exchanger tLbes werefouled and cooling watertemperature exceeded allowltlle maximums. Diesel ranfor I-h test. Reactor at 90%

1t-e diesel tripped on over

speed because of a governorfailure. 1t-e turbocharger

was also failed. 1t-e rel£tor was at 0"";

LNIT : Big Rock Point

LER E\ent DOtIn- E\ent type/No. date CG tine corrrrents SLbsystem Cause

82-19 [};/18/82 1 0:15 Autostart failure Electric Dirty Contl£ts on a startstart relay caused a start failure.

Diesel started on SJbsequenttest. 1t-e rel£tor was at 0%

83-9 DB/IO/83 1 Primary failure to start Fuel 1t-e diesel fuel oil punpfailed and the diesel tripped.1t-e rel£tor Was at 0%

83-JB 12122/83 1 Primary failure to start Cooling 1t-e diesel tripped becausethe coupling to the enginedriven cooling water punpfailed. 1t-e rel£tor was at86°',0

32

LNIT: Browns Ferry 1, 2, 3

LER E\ent DaNn- E\ent type/No. date CG time comrrents Stbsystem Cause

82-BJ 10/13/82 D Primary failure to start COltrol Dirty contl'Cts on mode switchswitch failed and the

Cllerator could not manuallyincrease diesel speed. Therel'Ctor was at 98%

81-~ 12/15/81 A Se::ondary failure to start/ Air start Air motors would not dis-llDisture in air En]age flywheel because of a

stuck solenoid val 'Ie. Therel'Ctor was at 95%

81-9] 12/11/81 D Primary failure to start Governor Oil leaked from the gJvernorcausing the diesel to tripon overspeed • The rel'Ctor\'Gs at 95%

81-61 10/10/81 C Se::ondary failure to run/ COltrol A miscalibrated relay causedhulll3.n error the diesel to trip mile it

\'GS being shut down. Therel'Ctor was at 73%

81-35 ~/20/81 B Se::ondary failure to start/ Air start The air-start system didgrit in air system not develop adeqJoce speed to

start the diesel. Thereactor was at 0%

83-57 00/23/83 A 4:00 Primary failure to start Urknown The diesel tripped on over-speed, but the cause was notdetermined. The reactor wasat 99%

82-45 00/28/82 J) Primary failure to start Governor The gJvernor friction plateslipped preventing the elec-trical governor from function-ing and causing the diesel tofail. The rel'Ctor was at 98%

81-4 01/10/81 3A Se::ondary failure to start/ Cmtrol The diesel generator trippedinstrument calibration m overspeed because of relay

miscalibration. Also theoutput breaker \\Ould notclose because the relaysetpoint was too high. Therel'Ctor was at 0%

33

!..NIT : Browns Ferry 1, 2, 3 (rontirlJed)

I£R Elent Dcwn- Elent type/No. date !Xi time COIII'OOnts Stbsystem C::YJSe

81-23 C5/l0/8l J: Autostart failure Air start Tre left-bS1k air-startmotors failed to start the

diesel on a test of the left-bS1k motors. Tre right-bS1kmotors problbly \'()uld havestarted the diesel- Tre

reactor was at 97%

8l-~ C5/06/8l D Autostart failure Air start Tre left-bS1k air-startmotors failed to start the

diesel on a test of the left-bS1k motors. Tre right-bS1kmotors problbly \'()uld havestarted the diesel. Trereactor was at 0%

8l-l9 C5/06/8l C Autostart failure Air start Tre left-bS1k air-startmotors would not start thediesel on a test of the left-bS1k motors. Tre right-bS1kmotors probablY \\Ould havestarted the diesel. Tt-ereactor was at 0%

83-62 10/04/83 C 10:00 Primary failure to start Air start Tre diesel was ltlut downbecause S1 air-startmotor engaged the flyl'tt1eel\\hile the e"lgine wascperating at 900 rpm. Treair-start SOlenoid was leak-ing. Tre reactor was at100%

83-52 08/16/83 J) 5:00 Primary failure to start GOIIernor Tre diesel \\Ould not attainrated speed because offailure of a hitj'l-!fleed limitswitch. Tre reactor was at94%

34

LNIT: Brunswick 1, 2

LER El.ent DC/o'In- El.ent type/No. date a:; tiroo C01lTIEnts SLbsystem Cause

82-151 12/14/82 1 Se::ondary failure to start/ LLbe oil LC/o'i Itbe oil pressure tripinstrument drift actuated because a tiroor

tirood out before pressurereached low trip setpoint.The setpoint was also out oftolerance for a:;s 3 and 4

82-133 11/05/82 4 Se::ondary failure to start LLbe oil A low lLbe oil pressure tripactuated because a timertirood out before pressurereached low trip setpoint.fl; 2 was unavailable fortesting. A similar fl; tripoccurred on 11/07/82. Thereactor was at I'D%

81-69 07/28/81 4 Autostart failure UrI<nown The a:; WJuld not load greater07/30/81 4 than 1000 kW en 07/28/81.

The fl; also failed to starten 07/30/81. ~ I'tBS

restarted imroodiately afterit failed. The reactor wasat 41%

82-78 07/01/82 2 Primary failure to start Cooling water A jacket water punp couplingto the engine drive shaft!tleared causing the dieselto trip. The reactor was at84%

81-32 02/23/81 3 Primary failure to start Centrol air Centrol air header pressureI'tBS low because of a leakingval I.e • Diesel 2 was alsobeing taken OJt of servicefor maintenance. The reactorI'tBS at 65%

82-64 03/21/82 3 Se::ondary failure to start/ Cooling water The diesel jacket water inletN..lIlBn error valve to the heat eXchanger

I'tBS closed and caused thediesel to trip en high

tellperature. The reactor wasat 9)%

35

LNIT: Brunswick 1, 2 (mntirued)

L.£R E\ent DCl'In- E\ent type/No. date a; tirre comrents Slbsystem Cause

81-143 12/28/81 4 Primary failure to run Uri<nown Diesel operation was unstableooove 1000 kW. No problemW3S foU1d. Tt-e reactor wasat 89%

81-145 12130/81 4 ~ondary failure to start/ Llbe oil SlLdge plLgged an oil-pressureslLdge in oil sensing line I'.hich caused

t:re switch to sense lowpressure. Tt-e diesel tripped.Tt-e reactor was at 89%

8l-{6 07/14/81 2 Autostart failure Cooling water Tt-e diesel tripped on highteJrperature in the jacketW3ter While an operator waSa1justing the teJrperaturesetpoint. Tt-e diesel wasrestarted. Tt-e reactor wasat 89~~

81-51 Qi/08/8l 4 Socondary failure to start/ Centrol air Moisture in a SOlenoidlIDisture mntrol val ve caused the

diesel to fail. Tt-e reactorW3S at 17%

81-55 Qi/14/8l 1 Primary failure to start Breaker A resistor in a logic circuitshorted and caused a lockoutrelay to l£tuate. Tt-e outputbreaker opened and the dieseltripped. Tt-e reactor was at00%

81-61 Qi/29/8l 4 Primary failure to start Exciter A mil failed and thegenerator field was notestablished. Tt-e reactorW3S at 9]%

83-tA 07/09/83 1 Primary failure to start Centrol Tt-e diesel tripped becauseof sticking contacts on thetimer relay. Diesel 2 wastested and it failed(ref. L.£R 83-tAA)

36

~IT: Brunswick 1, 2 (oontinued)

LER Elent DO'In- Elent type/No. date a; time corments SLbsystem Cause

B3-£tIA 07/09/83 2 Primary failure to start Cooling water He diesel tripped becausetJ-e ~rvice water outletvalle l'Ould not qJen. Unit 11'68 at 0% g1d Unit 2 was at89%

82-125 12/22/82 1 Primary failure to start COltroi He diesel tripped on lowILbe oil pressure signalcaused by air tr~ped in tJ-e~n8ing line. He rel£tor1'69 at 0%

82-123 10/10/83 Primary failure to start Output breaker During switching qJerationsa1 ESf' tus was deenergized;the a; started tut its outputbreaker failed to close

37

!..NIT : Cal.wrt Cliffs 1, 2

l.£R Ewnt Dewn- Ewnt type/No. date a:; time comrrents Stbsystem Cause

82-43 09/29/82 12 2:00 SECondary failure to start/ Breaker Tt-e a:; OJtput breaker \'()uld

hunan error not remain closed because the

bus disconnect key switch wasnot positioned to clear thetrip signal. Tt-e reactor wasat 100r.

82-52 09/13/82 11 SECondary failure to start/ ClJ1trol Tt-e diesel did not a::hievevibration ~ rpm in 10 s because of

a loose 'lJeed switch. Thiscaused a diesel trip. Tt-ereactor was at 100r.

82-44 09/15/82 21 SECondary failure to start/ Cooling water A jacket water pressurehunan error switch isolation val ve was

left closed after mainte-nance mich caused a dieseltrip. Tt-e reactor was at 0%

82-32 07/06/82 21 Primary failure to start UrI<nown Tt-e diesel failed to start,but the caUSe was not deter-mined. Tt-e reactor was at100%

82-31 (})/19/82 12 Primary failure to start Governor Diesel 'lJeed control failedaJch that load could not beincreased or decreased. Tt-ereactor was at 85%

81-19 nV02!81 12 Primary failure to start Breaker Tt-e diesel generator OJtputbreaker \'()uld not closebecause of damaged relayswitches. A similar eventoccurred on £¥I/21/81. Tt-ereactor was at 100r.

81-18 03/09/81 Primary failure to run Fuel oil Fuel oil leaked into theexhaust manifold and causedthe exhaust to smoke. Tt-ediesel was Slut down !¥ld theremaining oil was removed.Tt-e reactor was at 100%

38

LNIT: Cahert Cliffs 1, 2 (oontinued)

LER E\ent DCItITl- E\ent type/No. date a.; tiroo comrents Slbsystem Cause

81-64 m/n/81 11 Primary failure 1:0 start Centrol A blown fuse caused the

diesel to lose speed control00 the diesel was tripped.He reactor was at 100%

81-6 01/13/81 12 Primary failure to start Breaker TI'e output breaker to oneESF rus would not close.TI'e reactor was at 53%

83-46 m/16/83 12 Socondary failure to run/ Fuel TI'e diesel tripped on losshullBn error of fuel. TI'e day tank level

switches were isolated whichprevented the transfer punpfrom functioning. TI'ereactor was at 100%

83-44 m/OB/83 12 5:16 Primary failure to start Cooling water TI'e diesel tripped on lowjacket cooling water pressurebecause the jacket water wasairbound. TI'e reactor wasat 100%

83-18 [}'J/08/83 12 1:00 Primary failure to start Fuel TI'e diesel failed to startbecause of insufficient fueloil pressure. TI'e system wasmanually prirood. TI'e reactor\'.as at 100%

83-13 02/03/83 22 0:47 Primary failure to start Centrol TI'e diesel failed to starten an inadvertent under-voltage signal. No problem\'.as found. TI'e reactor wasat 0%

UNIT: Cronecticut Yalkee

39

LERNo.

81-D

83-12

Eventdate

00/03/81

05/17/83

2A

2A

Downtime

Event type/eaments


Primary failure to run

Slbsystem

Governor

Governor

Cause

The potentiometer to thegovernor control circuitfailed and the diesel couldnot phase onto the bus. Trerea:tor was at 100%

Tre diesel could not beloaded greater than 2800 kWbecause the governor setpoint had drifted. Trerea:tor was at 100%

UNIT: Cook 1

LER Event Down- Event type/No. date !Xi time eaments Slbsystem Cause

82-54 rJl/09/82 PB Primary failure to start Voltage The auto voltage regulatorregulator circuit failed, and the

exciter field overload relaytripped. Diesel CD was downfor maintenance. Tre rea:torwas at 0%

81-36 00/14/81 PB Secondary failure to run/ Fuel The diesel tripped when theprocedure error day tank emptied because of a

procedural error. Trerea:tor was at 69%

83-128 12/26/83 PB 23:29 Primary failure to start Control A grounded ta:horneter wirecaused a spurious trip of trediesel. Tre rea:tor was at76%

40

~IT: Cook 2

LER Event DCHl- Event type/f'Cl. date !Xi time coornents SLtlsystem Cause

83-12 01/26/83 PB 4:10 Primary failure to run Exhaust Exhaust was leaking fran 9"1exp9"1sion joint. Tre dieselwas shut dOllfl for repair.Tre rea::tor was at 48%

82-61 fIl/17/82 CD Primary failure to run Fuel Neither fuel oil tr9"1sferpunp would punp fuel to theday t9"1k because a checkvalve failure allowed fuel toflow ba::k to the storaget9"1k. Tre rea::tor was atl.Qm;

81-7 03/15/81 CD Primary failure to start Air start Tre diesel was shut dm«lbecause three air start injec-tion valves were stuck qJen.

Tre rea::tor was at (JJ,;

83-112 11/16/83 PB Primary failure to start Control A ta::haneter voltage-to-pressure tr9"1sdJcer setpointdrifted m caused a dieselfailure. Tre rea::tor was at(JJ,;

41

UNIT: Coqler

LER E\lent Down- E\lent type/No. date !Xi tine cooments Slbsystem Cause

82-20 10/04/82 2 Primary failure to start Ltbe oil A ruptured cylinder-linerseal leaked water intothelliJe oil and caused thediesel to trip. Tre reactorwas at 96%

82-16 07/12/82 1 Primary failure to start Control Drift in an overspeed protec-air tion valve caused a diesel

trip. Tre val\Ie was replacedand a section of control-airtubing with a small leak wasreplaced. Tre reactor was at75%

82-17 07/13/82 1 Primary failure to start LliJe oil LliJe oil low-pressure switchfailed and caused the dieselto trip. Tre reactor wasat 86%

82-10 05/17/82 1 Secondary failure to start/ Control A potential transforner dis-human error connect switch was opened

~ich caused a diesel trip.Tre switch was qJen because acabinet door was closedinproperly. Tre reactor wasat 82%

81-21 07/28/81 2 Secondary failure to run Fuel A fuel injector line brokebecause of fatigue, and thediesel was shut dOl«l. Trereactor was at 96%

81-19 07/28/81 1 Secondary failure to run/ Fuel A fuel~pply hose le~ed sovibration the diesel was shut down.

Tre reactor was at 96%

81-20 07/28/81 1 Secondary failure to start/ ClJ1trol Tre diesel failed to starthuman error air because of low control-air

pressure. Tre air leakedftre a ferrule had beencrinped. Tre reactor was at96%

81-7 04/26/81 1 Secondary failure to start/ Control A test gauge fell off themaintenmce error air control air system ~ich

caused low air pressure.Tre air dmpers closed par-tially and the engine over-reated. Tre reactor was at(JJ;\

42

UNIT: Crystal River 3

LER Event [)oo"n- Event type/

No. date !Xi time COIIIIIents Slbsystem Cause

82-12 02/26/82 A Secondary failure to start/ Air start TI-e air-start system did notclogged fitters provide ade~ate air to start

the diesel. Tre air systemwas cleaned. Tre reactor wasat ~

82-7 01/25/82 A Primary failure to start Exciter Tre diesel exciter failed tofunction, but no prcblem wasfound. Tre reactor was at100%

81-77 12/04/81 B Primary failure to start Control A control cable shorted andcaused loss of control power.Tre reactor was at 0%

81-30 OS/26/81 B Secondary failure to start/ Control Tre diesel tripped because ofcalibrated a misadjusted timing relay

81-30M: 06/16/81 B Secondary failure to start/ Cootrol Tre diesel tripped on a loss81-33 calibration error of off-site power because, of

a misadjusted timing relay.TI-e reactor was at 98%

81-24 04/14/81 A Secondary failure to start/ Llbe oil A plugged oil separatorcrud in oil caused high pressure in tre

crl:Jlkcase. Tre reactor wasat 0%

83-51 ll!07/83 B Primary failure to start Control Tre diesel tripped because ofa short circuit in a cootrolwire. Tre reactor was at98%

UNIT: Davis-8esse 1

43

LER Event DC1ftfl- Event type/No. date ~ tire conments Subsystem

83-22 04/13/83 1-1 Secondary failure to run/ Governormaintenance error

Cause

A loose connection in thegovernor caused eratic operation of the diesel. A terminal screw had been crossthreaded l'tt1ich resulted in aloose electrical connection.The re££tor was at m

83-15 03/04/83 1-1 Primary failure to start Governor Agovernor failure causederatic response of the diesel.During maintenance testingthe diesel output breakerfailed to close. The re££torwas at m

44

U\lIT : Dresden 2, 3

L£R Event lht'n- Event type/No. date !Xi tille CCIlIlents Slbsystem Cause

83-3 01/00/83 Z/3 Primary failure to run Cooling A cooling water pressurewater switch failed and caused an

alarm. The diesel wasmanually tripped. Thereactor was at OJ;;

82-45 11/09/82 3 Secondary failure to start/ Cooling The diesel tripped on lowdesign error water cooling-water pressure caused

by a bad switch. Diesel 2was down for maintenance.The reactor was at 9B%

81-37 11/19/81 Secondary failure to run/ Cooling A cooling water check valvedesign error water failed and caused excessive

terrperature and a manualtrip. These valves werereplaced on all diesels. Thereactor was at 60%

81-33 10/23/81 Z/3 Secondary failure to start/ Cooling Diesel Z/3 was trippeddesign error water because of high cooling-water

terrperature. Diesel 3tripped because of high

cooling-water terrperature in asubsequent test. The causewas not found. The reactorwas at 66%

81-27 09/17/81 3 Primary failure to start Air start The diesel generator trippedbecause of failure of theair-start regulator valve.There was a leak in thevalve. The reactor was atOJ;;

83-5 OZ/OB/83 3 Secondary failure to start/ Air start The diesel failed to startlOOisture in air was probable because of failure of the aircause IOOtors to function. The

reactor was at m

45

~IT: Joseph M. Farley 1, 2

LER Event 1hIn- Event type/No. date ~ time coornents Slbsystern Cause

81-53 12/10/81 2C Secondary failure to start/ Air start An operator closed the air-hull1S1 error start isolation valves

instead of the crosso<onnectvalves which are in closeproximity. The diesel failedto start. The reECtor was at99%

81-43 09/18/81 1.C Secondary failure to start Engine The diesel tripped on high

crmkcase pressure enexhaust leaked past twoscored cylinders into the oilpunp. The reECtor was at100%

81-67 09/27/81 2C Secondary failure to start Ergine The diesel tripped on high

crankcase pressure enexhaust leaked past a scoredcylinder liner into the oilpunp. Diesel 1.C was down formaintenance. The reECtor wasat 100%

81-48 07/08/81 2C Primary failure to start Voltage The diesel generator did notregulator attain rated voltage because

of a blown fuse in the regu-lator. The reECtor was at100%

81-44 06/10/81 1.C Primary failure to start Voltage The voltage regulator failedregulator ","en the engine-running

relay failed. The reECtorwas at m

81-32 05/08/81 1.C Primary failure to start Engine The diesel failed to startbecause of water in acylinder. The reECtor was at100%

81-13 05/05/81 2B Secondary failure to start/ Llbe oil A lube oil strainer O-ringvibration leaked and caused a diesel

failure. The reECtor was at0%

46

lJIIIT : Joseph M. Farley 1, 2 (continued)

LER Event Down- Event type/No. date !Xi tirre cooments Subsystem Cause

81-21 04/13/81 2C Primary failure to start Voltage The diesel generator output

regulator voltage decreased to 0 Vbecause of blown fuses in thevoltage regulator. There~tor was at rn;

81-10 03/18/81 16 Primary failure to start Governor The diesel tripped l'ttlen powerto the governor failedbecause of blown fuses. There~tor was at rn;

83-79 ll!20/83 1-2A Primary failure to start Engine Excessive noise and loadoscillation were caused by acr~ked cylinder liner. There~tor was at 100%

83-33 00/10/83 2B 3:59 Primary failure to start Air start The diesel failed to startbecause of excessive wear onthe starting air distributor.The re~tor was at 100%

83-16 04/12183 16 20:33 Primary failure to start Fuel The diesel failed to startbecause of failure of aconstant vent check valve.The re~tor was at 100%

UNIT: Janes A. FitzPatrick

47

LERNo.

82-21

81-71

Eventdate

05/01/82

10/27/81

A

BD

Dor.otime

Event type/COlIIlIents

Autostart failure


St.bsystem

Cmtrol

Coolingwater

Cause

Tt-e diesel was rellDved franservice because of voltageand freq,Jency fluctuations.Tt-e fluctuations were coincident with roomentary groundson a 125-V de system. Tt-ediesel was retested withoutproblems. Tt-e reactor wasat m

Tt-e service water Pullp didnot start when diesel Dstarted. Tt-e pUIlp did notstart because of a dirtycontact. Diesel B is cooledby tt-e sane service waterPUIlp. Tt-e reactor was at70%

UNIT: Ft. Calhoun

LERNo.

82-7

Eventdate

03/24/82 2

Downtime

Event type/conments


St.bsystem

Coolingwater

Cause

Tt-e diesel was shut dOlIfl~n a coolant expansion tubeleaked. Tt-e reactor was at93%

48

UNIT: Fart St. Vrain

LER Event Down- Event type/

No. date rx; tine COIlIrents Slbsystem Cause

81-35 05/11/81 B Primary failure to start E>d1aust An e>d1aust temperature switchfailed and caused the dieselto trip. The re~tor was at70%

81-57 09/8/81 B Primary failure to start ErYJine A clutch bearing failed. Theengine was returned to ser-service by replacing theclutch bearing Efld shaft.The re~tor was at 70%

81-29 04/20/81 B Primary failure to start Fuel The diesel would not loadbecause of a failed fuelinjector. The re~tor wasat 50%

81-31 04/27/81 A Primary failure to start Governor One of the two tandem enginestripped because of wornlinkage between the governorEfld fuel r~ks. The reactorwas at ~

83-18 05/17/83 B 0:25 Autostart failure diesel Control The diesel was connected in

parallel to grid/CCF parallel with the off-sitepotential because the load- power en off-site powershed relays were not tested failed. The diesel trippedseparately on overload because the load-

shed relays had failed. Thediesel was restored in25 min. The reactor was at0%

49

UNIT: Grand Gulf 1

LER Event Down- Event type/No. date DG time conments Slbsystem Cause

83-101 07/18/83 13 12:00 Primary failure to start UrknQ\\fl Tre diesel tripped, lJJt nocause was found. He rea::torwas at ~

83-82 07/17/83 II Primary failure to run/ Air start Tre diesel failed when anran 16 h air-start valve to a cylinder

qJened. Tre rea::tor was atoro

83-136 00/30/83 II Primary failure to run/ Llbe oil Tre diesel was shut downran 98 min because of e><haust leaks and

broken welds on tre llbe oilintercoolers. Tre rea::torwas at ~

83-167 10/22/83 12 Primary failure to run/ Fuel oil Tre diesel was shut dQ\\flran 27 h because of a fire hazard

caused by a fuel oil leak.Tre reactor was at ~

83-189 12/07/83 13 Primary failure to start Breaker Tre diesel output breakertripped because of a shortedresistor. Tre diesel alsotripped, lJJt a reason forthe diesel trip was notdetermined. Tre rea::tor wasat ~

83-126 09/04/83 II Primary failure to run/ Fuel Tre diesel had run 8.3 h I'tlenran 8.3 h a fuel line ruptured and

caused a fire. Tre rea::torwas at ~

83-179 ll!O5/83 12 Primary failure to run Fuel Tre diesel was shut downbecause of a fuel oil leak.Tre rea::tor was at 2%

83-178 ll!OO/83 12 Primary failure to run/ Air start A starting air valve failedran 70 h q>en after 70 h of q>eration.

Tre diesel was shut down formaintenance. Tre rea::tor wasat 4%

83-167 1O/2Z/83 12 Primary failure to run/ Fuel Tre diesel had run 27 h whenran 27 h it was shut down because of a

fuel oil leak. Tre reactorwas at oro

50

~IT: Gra1d Gulf 1 (calti......ed)

l£R Event 1hIn- Ellent type/No. date Ili time conments Slbsystem Cause

83-82 rIl/17/83 11 Primary failure to run/ Air start A starting air vallie failedrS1 16 h cpen after 16 h of a 24 h

test. The diesel was shutclown for repair. The re~tor

was at m;

83-82 rJ7/17/83 11 Primary failure to run/ Air start A starting air vallie failedrS1 6 h q>en after 6 h of q>eration.

The diesel was srut down forrepair. The re~tor was at0%

82-33 00/14/82 13 4 days Primary failure to start Protection Pll I-PCS diesel engine waslogic tripped by a faulty over-control speed t~hooeter. The

re~tor was at m;

82-11 rJ7/22/82 12 Secondary failure to start/ Cooling Pll indicator on the j~ket

valve design error water cooling water vallie gavefaulty indication, S1d thediesel tripped on overtem-perature in j~ket waterbecause a valve was closed.All of the valves were taggeduntil the design error wascorrected. The re~tor wasat m;

83-182 11/29/83 13 69:18 Primary failure to start Control The diesel did not start onloss of power to the busbecause of a bad cont~t inthe nDde-eelect switch. There~tor was at m;

83-140 09/02/83 11 Primary failure to start Voltage The voltage regulator did notregulator caltrol the output voltage

dJring a loss of power test.The re~tor was at m;

83-62 05/04/83 12 Primary failure to run Fuel The diesel fuel r~ks werebinding S1d could not be

ITOved. The re~tor was at0%

83-129 08/27/83 Secondary failure to start/ Cooling water The plS1t was shut clown whenhullSl error S1 inadvertent safety

injection signal occurred.The !Xi tripped because theservice water valves wereclosed for maintena1ce

51

UNIT : Eelwin I. Hatch 1, 2

LER Event DCHl- Event type/No. date IX; time COIII1IBnts Slbsystem Cause

81-127 12/16/81 :£ 13 days Primary failure to start Engine A rod c~ bolt c~ loose Slda rod separated frClll thecrllfll<shllft • The reEtor Wil6

am

82-79 U7/27/82 C Primary failure to start/ Engine Engine cmnecting rod bem-ingr91 J7 min failed. The engine WB8

repaired. The reedor was atm

82-33 04/20/82 18 Primary failure to start Urkno\on The diesel tripped, DJt ablO'llfl fuse in 91 ~iatorWIIS the only abnol'lllel condi-tion f0lMld. The rea:tor MIS

at~

81-129 12/17/81 2A Primary failure to stal't Uri<nown Diesel :£ failed, Sld ~ile

:£ it was uOQvailable diesel 2AW86 rellDved fran service formaintel1ilOCe. The rea:tor WB8

at 97~

81-134 12/30/81 Primary failure to start Cooling Pressure fluctuations in thewater diesel jfCket water caused a

diesel trip. The reliCtor WB6

at 95~

81-94 09/21/81 :£ Primary failure to run Goverl1Ol' The governor fttJUld notrespond to~ adjustments.The rea:tor W86 at ~

81-66 06/26/81 2B I\Jtostart failure Cooling Service W8ter flow to thewater diesel waa blocked !I1d caueed

the dieeel to trip. ThestS"ld>y service water MIS

q>erable. The rea:tor W9S atm

81-64 06/26/81 A Primary failure to start Governor The diesel speed could not beadjusted because of a speed-control ~tor failure. ThereEtor W9S at 9~

81-35 04/26/81 18 Primary failure to start Cooling St91dby service W9ter fttJUldW9ter not deliver rated flow.

Dieeel Ie W9S dol«1 for IllElin-ten91Ce. The rea:tor W9S at~

52

UNIT: Edwin I. Hatch 1, 2 (continued)

LER Event 1hIn- Event type/No. date Ili tine corrnents SWsystem Cause

81-26 04/05/81 All Autostart failure Breaker The diesel generator breakersfailed to close automaticallyfollowing a loss of off-sitepower test. The breakers weremanually closed. The causewas undervoltage relayfailure. The reactor was at0%

83-45 00/16/83 lA Primary failure to start Governor The diesel failed to startbecause a shutdown solenoidald plunger on the diesel\'ere bent. The reactor wasat 99%

83-83 00/01/83 lA Primary failure to start Fuel The diesel did not startbecause the fuel system wasinadeq..aately prined. Thereactor was at 100%

83-26 06/10/83 2C Primary failure to start Governor The diesel failed to startbecause the shutdown solenoidwas sticking. The reactorwas at 0%

83-52 05/06/83 18 Secondary failure to start/ Control The diesel was shut downhuman error because of alarms. The

problem occurred because acontrol power switch was leftoff. The reactor was at 99%

UNIT: IrdiS1 Point 2, 3

53

LERNo.

81-18

Eventdate

07/10/81 21

Downtime

Event type/COIlIrents

Autostart failure

Stbsystem

Air start

Cause

The diesel tripped because ofan overerank, l:xJt it wasreset and restarted. The airsupply regulator was setinproperly. One of the airstart motors had been disabled for the test. Therel£tor was at 100%

UNIT: Kewaunee

LERNo.

81-2

83-5

Eventdate

01/13/81

02/16/83

lB

Downtime

Event type/COIlIrents

Se::ondary failure to start/moisture in air


Subsystem

Air start

Coolingwater

Cause

Diesel lB failed to startbecause of moisture in theair-start system. The rel£tor was at 100%

A cooling water valve to theoil cooler failed to cpenconpletely. The diesel wasremoved fran service forrepair. The rel£tor was at100%

~IT : La:rosse

54

LERNo.

83-D

83-11

EYentdate

12/12/83

12/09/83

18

18

EYeOt typelCOIlIIIentS

Prilll8l'y failure to stert

Pri11llU'Y failure to start

Slbsystelll

Electricstart

Electricstart

Cause

Tt-e diesel failed because thestarter IIKltor relIIainedengaged. The rea::toc W86 at~

Tt-e dieeel failed to startbecalMle of failure of thestarter ootor. The reiCtorWl!l6 at ~

~IT: LaSslle 1

LERNo.

83-15

EYeOt

date

02/17/83 18

1h«1lillie

ElIeI1t t~1COMel1ts

Pri"*,y failure to start

Slbsystelll

GoYernor

Cause

Tt-e diesel speed fluctuatedbecause of a loose connectionto tt-e run solenoid. Tt-ereEtOl' WE at ~

55

UNIT : t-t:Guire 1, 2

L.£R Event DC1f«1- Event type/No. date £Xi time cooments Slbsystem Cause

82-30 04/23/32 lA Secondary failure to start/ Urknown n-e diesel failed to starthUIlllll1 error because of errors made during

ellJipment roodification • Thereactor was at 50%

81-191 12/15/81 lB Primary failure to run Cooling Acooling-water leak drainedwater the surge tank and caused a

failure during a 24-b..-dieseltest. The reactor was at lR

81-27 03/06/81 lB Primary failure to start Voltage The diesel generator outputregulator voltage failed low. During

a subsellJent start the dieseloutput oscillated because theshutdown valva was ventingintermittently. The reactorwas at lR

83-34 07/06/83 2A Primary failure to start Voltage The diesel failed because ofregulator a malfunctioning transformer

in the voltage regulator.The reactor was at lR

UNIT: Maine Yankee

L.£RNo.

82-40

82-07

Eventdate

12/11/82

03/03/82

Down-£Xi time

lA 3 days

A

Event type/cooments


Secondary failure to start/roisture in air

Slbsystem

Exciter

Air start

Cause

The exciter failed \llt1en aspring-coil assembly vibratedloose. The reactor was atlow-power physics testing

n-e air~tart rotors wouldnot disengage the flywheelring !Jlar because a solenoidvalve stuck open. Thereactor was at m%

56

1111IT: Millstone 1, 2

L£R Event 1hIn- Event type/No. date !Xi time carments Sltlsystem Cause

82-21 09/13/82 !Xi Secondary failure to start/ Centrol Acurrent tra"lsformervibration connection broke S1d caused a

diesel trip. The res::tor wasat m;

81-24 06/02/81 B Autostart failure Cooling The cooling water supplyvalve failed to q>en auto-matically. The valve wasq>ened manually S1d thediesel was restarted. Theres::tor was at 10m;

81-31 00/25/81 A Primary failure to start Caltrol The diesel tripped because ofa loose cennector. The res::-tor was at 10m;

81-8 04/27/81 DG Primary failure to start Caltrol The diesel tripped on hig,crS1kcase pressure. Theres::tor was at m;

81-5 01/02/81 B Secondary failure to start/ Cooling After a loss of power to thehuman error water emergency bus, the diesel

started but tripped on aconnector was sprayed byleaking service water. Aservice water gasket leakedbecause it was iJlprq>erlyinstalled. The res::tortripped because of a loss ofde power

83-4 02/07/83 DG Secondary failure to start/ Air start The diesel failed to start/lI)isture in air because the air-atart sole-

noids did not q>en. Theres::tor was at 10m;

UNIT: t-b1ticello

57

LERNo.

82-7

Eventdate

U7/26/82

Downtime

Event type/comnents

Secondary failure to start/human error

St.bsystem

Governor

Cause

An operator inadvertentlychMged the adjustment onthe governor shutdownsolenoid nn adding oilto the governor \\tlich causedthe ~ to fail to start. Thereactor was at 7zx,

UNIT: Nine Mile Point

LERNo.

81-1

Eventdate

01/07/81

Downtine

Event type/comnents

Secondary failure to start/loose wires

St.bsystem

Voltageregulator

Cause

The voltage regulator wasshorted nn loose bailingwire fell onto it. Thegenerator output breakertripped because of excesssivecurrent. The reactor was at91%

58

UNIT : North Arna 1, 2


No. date !Xi tine conments SltJsystem Cause

82-13 03/08/82 2H Autostart failure There was an attetlJlt to starta diesel prior to the fuelsupply relay timing out. Anoff-site source was unavail-able so energency buses werecross-tied. The reactor wasat (]I;

82-69 10/20/82 2J Primary failure to start Exciter Generator field did not flashbecause a latch trip coilfailed to energize. The coilwas replaced. The reactorwas at 10m;

82-36 05/16/82 IJ Primary failure to start Breaker The diesel generator outputbreaker failed to closebecause an undervoltage relayhad failed preventing thebreaker closure. The reactorwas at 74%

82-7 03/12/82 2J Primary failure to start Voltage The voltage regulator failedregulator II1d caused the diesel to

trip. Diesel 2H was down formaintenance. The reactor wasat Ct'6

83-54 07/04/83 2H Primary failure to run/ Lube oil The diesel tripped on jacketrEn li8 min water high tenperature caused

by low oil level. The reac-tor was at 100%

83-50 06/13/83 2J Primary failure to start Cooling The diesel tripped on highwater pressure in the crankcase

after cooling water leakedinto the crankcase. Thewater also caused a pistonand cylinder liner to crack.The reactor was at 100%

UNIT: Oyster Creek

59

LERNo.

81-47

82-5

Eventdate

10/05/81

01/25/82 1

Downt.irre

Event type/c:ooments


Secondary failure to start/water corrosion

Subsystem

Governor

Radiator

Cause

The governor failed such thatthe diesel would not loadgreater than 2400 kW. Thegovernor was replaced. Thereactor was at 0%

Low water level caused by aradiator leak resulted in adiesel trip. The bile wasplugged. The reactor wasat 0%

UNIT: Palisades

LER Event Down- Event type/No. date !Xi time c:ooments Sltlsystem Cause

82-9 02/02/82 1-1 Primary failure to start Governor Load and freqJency oscilla-tions were caused by adefective governor. Thereactor was at 90%

81-28 07/03/81 1-1 Secondary failure to run/ Cooling Jacket water leaked whichvibration water reqJired a shutdown of the

diesel. Vibration caused anipple to work loose. Thereactor was at 100%

81-26 06/26/81 1-1 Primary failure to start Governor The motor-driven speed con-trol circuit failed, md thediesel did not reach ratedspeed. The reactor was atm

83-15 02/21/831 1-1 Primary failure to start Governor The generator output ~nt to65 Hz because of ffl iJrpropersetpoint for the governor.The reactor was at 0%

60

LNIT : P~h Bottan 2, 3

LER Event Ih«l- Event type/r-tl. date !Xi time caments Slbsystem Cause

81-44 11/05/81 E-l Autostart failure U~ The diesel failed to startthree times but wasimmediately followed by threesuccessful starts. The rea:-tor was at 93%

81-26 09/21/81 E-4 Secondary failure to start/ Cooling A cooling-water valve had

human error water been left closed after main-tenmce. The diesel failedbecause water had leaked franthe turbocharger gaskets intothe intake md exhaust mani-folds. The rea:tor was at48%

81-4 01/14/81 E-3 Primary failure to start Breaker M output breaker would notclose because m interlockswitch was misaligned. Therea:tor was at 100%

l)jIT: Pilgrim 1

61

LERNo.

82-12

83-33

Eventdate

04/30/82

06/01/83

A

B

00«1time

Event type/conments



Slbsystem

Crotrol

Governor

Cause

Tt-e diesel t~hometer unitfailed and prevented tt-ediesel fran starting. Tt-ere~tor was at 99%

Tt-e diesel failed becausethe governor was notfunctioning properly. Tt-ere~tor was at 100%

UNIT: Point B~h l, 2

LERNo.

83-2

Eventdate

03/09/83

Down

timeEvent type/conments


Slbsystem

Governor

Cause

Tt-e diesel failed to startbecause tt-e fuel r~ks werein tt-e low-fuel position.Tt-e governor failed toposition tt-e r~ks after tt-eprevious test. The re~tor

was at m;

62

LNIT: Q..Jad Cities 1, 2


No. date rx; time comnents Slbsystem Cause

82-12 06/22/82 1/2 Secondary failure to start/ Exciter Diesels 2 and 1/2 started on1 design error a loss of off-site power and

trip of Unit 2. Diesel 1/2tripped on underexcitationl'tlich should have beenby-passed on autostart, butbecause of a design error wasnot. Attempts to restart rx;1/2 failed. Therx;wasrestored to service by reset-ting a lock-out relay.Diesel 1 was down for main-tellS1Ce but Unit 1 did notlose off-site power. Unit 1was at 53%

81-2 01/07/81 Primary failure to start Fuel oil The diesel tripped because ofa loose fuse in the fuel con-trol circuit. The circuitbreaker conta::ts were alsoslightly misaligned. Therea::tor was at m

82-18 10/06/82 Secondary failure to start Cooling The diesel tripped on high

water temperatures caused by foul-ing of the heat eXchanger.Both heat exchangers wererepla::ed. The rea::tor wasat 96%

82-~ 12/24/82 1/2 2:40 Primary failure to start Air start The diesel failed to startbecause of inade~ate airpressure. A cra::k in an airline caused the problem. Therea::tor was at 23%

63

UNIT: RS1Cho Seeo

LER Event Down- Event type/No. date rx; tine comnents Slbsystem Cause

82-22 09/23/82 A Autostart failure Air start Tt-e IOOtor oil reservoirin the ac powered air com-pressor was elIpty. Tt-ediesel failed to start on theac system but was started onthe de system. Tt-e reactorwas at 95%

81-35 06/25/81 A Primary failure to run Governor A slow oil leak frCJD tt-egovernor caused unstableoperation of the diesel. Tt-ereactor was at 50%

UNIT: Rd:linson 2

LERNo.

81-25

81-30

Eventdate

11/02181

11/30/81

B

B

Downtine

Event type/comnents



Slbsystem

Fuel

Voltageregulator

Cause

Tt-e fuel system lost itsprine I'ttlich resulted in adiesel failure to start. Tt-ereactor was at 50%

Tt-e diesel generator outputvoltage did not attain ratedvoltage. Tt-e voltage adjustrheostat was replaced. Tt-ereactor was at IJ',;

64

UNIT: St. Ll£ie 1, 2

LER Event 1hIn- Event type/No. date Ili time conments Slbsystem Cause

82-33 07/21/82 lB 55:00 Primary failure to start Turbocharger The turbocharger soak ba::koil pUIlp coupling failedl'kIich caused inadeqJate llbri-cation to the turbocharger.The rel£tor was at m

82-24 06/16/82 lB 52:00 Primary failure to start Turbocharger The turbocharger failedbecause it did not receiveadeqJate Itbrication fran adeteriorated soak ba::k Itbri-cation pUIlp. The re!£tor wasat m

82-11 03/09/82 lA 62:00 Primary failure to start Control A speed switch shorted 91dcaused the diesel to fail.The rea::tor was at 98%

65

UNIT: Salem 1, 2

LER Event DCMIl- Event type/No. date [Xi time conments SWsystem Cause

82-115 09/28/82 2A SecClldary failure to run/ Cooling Silt in the cooling watersilt in water water caused erosion of a pipe

\'tlich leaked. The diesel wasshut down for repair. Thereector was at B2%

81-107 10/04/81 2B Secoodary failure to start/ Cooling The diesel tripped on highhuman error water temperature in the jacket

water. The service waterdischarge-Valva cClltrollerhad been set to the fUllyclosed position. The reactorwas at m;

81-29 03/14/81 lA SecClldary failure to run/ Governor The diesel could not beprocedure error loaded greater than 1400 kW

because of low oil in thegovernor. There were no pro-cedures to check the oillevel. The reactor was at100%

83-65 12/07/83 2B Primary failure to start Voltage The diesel failed to functionregulator because of a shorted trans-

former in the voltage regula-tor. The reECtor was at m;

83-63 11/18/83 2C Primary failure to start Governor The diesel did not exceed180 rpm because the fuelracks did not qJen. Thereactor was at m;

83-58 11/07/83 2B Primary failure to start Fuel The diesel failed to main-tain speed because of a loosecoupling to the shaft~iven

fuel oil punp. The reactorwas at m;

83-67 12/31/83 2B Primary failure to run Fuel oil The diesel was shut dQlolflbecause of a fuel oil leak.The reactor was at m;

83-15 02/10/83 lA Primary failure to run Cooling The diesel was trippedwater because of a jacket water

high tenperature alarm. Thecooling water valve hadqJened partially but notcoopletely. The reactor wasat m;

66

IJIIIT : Sal lhlfre 1, 2, 3

LER Event DcAoIn- Event type/No. date DG tine cooments Slbsystem Cause

82-15 05/12/82 ZGOO 3 Primary failure to start Governor A poI'Ier supply nrxlule for thegovernor failed and caused adiesel to trip. The reactorwas at (JJt;

81-29 11/19/8}. 1 Secondary failure to start/ Governor The diesel tripped because ofhuman error inadequate oil in the

governor. Tt-fl oil level hadnot been restored after main-tenance. Diesel 2 was cb.flfor maintenance. The reactorwas at 87%

83-71 06/21/83 ZGOO2 Secondary failure to start/ Air start The diesel failed to starthuman error because an air start valve

was closed. The reactor wasat (JJt;

83-)] 04/19/83 ZGOO2 4:22 Primary failure to start Cmtrol The diesel started but couldnot be loaded because offailure of a relay. Thereactor was at (JJt;

81-17 07/14/81 Secondary failure to run/ fuel An oil line cracked, ~rayed

vibration oil mto an exhaust pipe, and

the oil caLJglt fire. Thefire was extinguished in8 min. The reactor (Unit 1)

was at 90%

81-15 06/30/81 2 Secondary failure to start/ Lube oil Low lube oil tripped thedesign deficiency diesel. Tygm tubing that

was part of level~asuring

system leaked oil. Tygm wasthe wrong material. Thereactor was at 95%

83-83A 11/25/83 3GOO3 Primary failure to start Air start The diesel tripped for anul'lknol«1 reasm, but it l'«lUldnot restart because of blowngaskets in both air can-pressors. Valves betweenthe coopressor and airreceiver had stuck open.This event occurred twice.The reactor was at (JJt;

LNIT: Sa1 lJlofre 1, 2, 3 (continued)

67

LERNo.

83-83B

83-01

Eventdate

11/23/83

02/23/83

3GOO3

1

OlWltime

Event type/COImIeOts


Secondary failure to start/I1ull&1 error

SlDsystem

Ccntrol

Cause

The diesel failed to startI't1en four de circuit breakerstripped. Incorrect l~s\ere installed in a pushbutton, 3ld~ the buttcnwas depressed the bulbsshorted the 125-V cb. Thereactor was at re;

68

UNIT : 5eqJoyah 1, 2

LER Event Da..n- Event type/No. date lli tine COIIIIIents Slbsystem Cause

83-1 12/19/82 18-8 Primary failure to run/ Llbe oil A llbe oil leak was caused byran 21 h bad threads on a pipe. The

leak occurred after 21 h intoa 24-h test. The reactor wasat ~

81-155 12/09/81 ZA-A Secondary failure to start/ Governor A bad solder joint on a plughuman error prevented the diesel from

loading greater than 1300 kW.The reactor was at ~

83-168 11/18/83 lA-A Primary failure to start Crotrol A short-circuited larp holderblew fuses in the controlpm.er to the start circuits.The reactor was at 1O~

83-70 05/12/83 lA-A Primary failure to start Cooling The engine tripped on highwater and pressure in the crankcaseengine v.tlen water leaked in through

the oil cooler. A cylinderliner was also found damaged.The reactor was at 1O~

83-1 12/14/82 28-8 Secrodary failure to start/ Control The diesel generator tripped

cable insulation degradation on differential currentsignal caused by failed con-trol cables. The reactorwas at ~

82-58 04/29/82 ZA-A Secrodary failure to start/ Crotrol The diesel tripped on crank-human error case overpressure before

reaching 900 rpm because theswitch assembly reset buttonhad not been latched pro-perly. The reactor was at100%

83-26 02/23/83 lA-A 6:17 Primary failure to start Cooling The diesel failed because awater cooling water valve failed to

q:Jen. The reactor was at100%

83-10 01/18/83 lA-A 4:01 Primary failure to start Cooling The diesel failed because awater cooling water valve failed to

qJeI1. The reactor was at ~

UNIT: 5eqJoyah 1, 2 (continued)

69

LERNo.

83-171

83-186

83-188

Eventdate

12/06/83

12/09/83

12/21/83

DG'I'Il

time

lA-A 14:35

lA-A

lA-A

Event typelCOIlIrents


Secondary failure to startlhUIl81 error


SLbsystem

Governor

Engine

Governor

Cause

The motor-operated potentiometer failed such that thediesel load could not be

reduced. The reactor was at100%

The diesel tripped on highpressure in the crankcase. Apiston and two cylinderliners were cracked and theturbocharger gear drive wasdanaged. Wrist pin bolts hadnot been torqued properlyduring manufacturing. Thereactor was at 100%

The diesel governor failed tocontrol the load because of acorroded connector to thegovernor. The diesel loaddecreased from 4 t-fH to zero.Unit 1 was at 0%; Unit 2 wasat 100%

70

LNIT : SulIRer 1

L£R Event Dol«1- EWrlt type/No. date [x; time COIIIlIeflts Slbsystem Cause

82-61 12/18/82 B 0:30 Primary failure to start Llbe oil The diesel tripped on lowllbe oil pressure, but thecause is unl<nolr.n. The [x; wasrestarted 30 min laterwithout problems. Thereactor was at .l%

83-87 00/03/83 18:33 Primary failure to start Cmtrol The diesel l«)lIld not startbecause of dirty contacts ona maintena1CEl/local/remoteselector switch. The reac-tor was at 100%

83-82 07/18/83 B 13:33 Primary failure to start Cmtrol The diesel tripped on spur-ious hi91 cr!l1kcase pressuresignal. The reactor was at100%

LNIT: Surry 1, 2

L£RNo.

81-:JJ

Eventdate

05/04/81

Dol«1time

Event type/COIIIlIents

Secondary failure to start/neinten!l1Ce error

Slbsystem

CCIltrol

Cause

A misaligned overspeed triplimit switch actuated andtripped the output breaker.The reactor was at 100%

71

lJ'JIT : Susq,Jehanna 1

LER Event [)a;on- Event type/No. date ~ time comnents Subsystem Cause

82-~ 11/05/82 D IlI.Jtostart failure Cmtrol An overvoltage protectionrelay was sensitive tofreq,Jency I'thich caused it totrip when the voltageincreased too r",idly. Therelay was replaced with arelay not sensitive tofreq,Jency. The reactor wasat rn;

82-47 10/27/82 Primary failure to start Control A vibration switch 91d pres-sure regulator caused adiesel to trip. The reactorwas at rn;

83-68 04/19/83 C Mostart failure Voltage The diesel started slowly andregulator tripped on overvoltage. The

diesel was restartedinmediately. The reactor wasat rn;

72

UNIT : TUI.'key Point 3, 4

LER Event Datm- Event type/No. date £Xi time cannents SWsystem Cause

82-6 OS/27/82 Primary failure to start Fuel A fuel oil relief valvaleaked m caused low fueloil pressure wch caused adiesel trip. The rea:ltorwas at 100%

81-12 ll!24/81 A Autostart failure Breaker The diesel output breaker didnot close because relays thatsense tripping of bus loadsfailed. The rea:ltor was at0%

81-15 11/12/81 A Secoodary failure to start/ Air start M air~art rmtor failed tormisture in air disengage. The B diesel was

down for maintenance. Therea:ltor was at 0%

81-1 01/01/81 B Primary failure to start Voltage TI'«) fuses failed in the volt-regulator age regulator circuit gld

resulted in loss of voltagecootrol. The rea:ltor was at100%

83-25 12/16/83 B Primary failUl.'e to start Air start The diesel failed to start 00

a spurious safety inspectiona:ltuation signal. The dieselfailed because of a defectiveair~art pressure regulator.The rea:ltor was at IJ%

73

lJIIIT : VerllDnt Ylflkee

L.£R Event Down- Event type/No. date !Xi time conments Slbsystem Cause

81-14 05/18/81 A Primary failure to run Cooling A gasket in the cooling waterwater jacket had a large leak at a

cylinder. The diesel wasshut down. The re~tor wasat lOO%

83-20 08/26/83 8 Primary failure to start Cmtrol The diesel failed to startbecause of a failed stq>pingrelay. The rea::tor was atlOO%

UNIT: Ylflkee Rae

L.£RNo.

81-16

Eventdate

07/06/81 1

Downtime

Event type/conments

Secmdary failure to run/water corrosion

Slbsystem

Radiator

Cause

Corrosion blocked theradiator and caused thediesel to overheat. Therea::tor was at rn;

74

UNIT: Zion 1, 2

L£R Event Down- Event type/No. date ~ tine cooments Slbsystem Cause

83-2 01/31/83 0 Primary failure to run Turbocharger Tre diesel would not loadgreater than 50% because ofa failed turbocharger. Atthe sane tine diesel 28 wasunavailable because of Sloil leak. Tre re~tor wasat m

82-33 10/15/82 18 Autostart failure Llbe oil Clogged filters in the llbeoil caused low oil pressureto the turbocharger. Thediesel would not have trippedon a safety injection signal.DG lA was out of service atthe tine. The re~tor wasat 100%

82-25 00/11/82 0 Secondary failure to start/ Lube oil The turbocharger lube oilvibration filter vibrated loose S1d a

lube oil fire resulted. AsNJtdown was begJn because ~lA was also unavailable, but~ lA was restored before theunit re~hed hot shutdown.

Tre re~tor was at 100%

81-36 01/06/81 lA Primary failure to start Engine The intake rocker arm broke,and the diesel was shut doot.n.The re~tor was at 92%

83-26 00/01/83 0 Primary failure to run/ ClJ1trol The diesel tripped on reverserSl 2 h air power when a control-air

regulator failed. The re~-

tor was at m

83-J9 09/21/83 0 Secondary failure to start/ Governor The diesel tripped on over-hulJB"l error speed because of governor

misadjustnent. The re~tor

was at 0%

82-20 00/22/82 28 Primary failure to start Air start A coupling fran the engine'scSllShaft to the air-atartdistributor was broken. Trere~tor was at 100%

81-4 04/14/81 0 Primary failure to run/ ClJ1trol Tre diesel tripped when arSl J9 min ta=honeter wire broke. Tre

re~tor was at 91%

UNIT: Zion 1, 2 (continued)

75

LERNo.

83-23

83-7

Eventdate

07/27/83

01/31/83

o

o

1hIntime

E\lent type/conments



SLDsystem

Centrolair

Turbocharger

Cause

Tt-e engine master pneumatic~vice failed and caused treengine to trip. Tt-e rea::torwas at m

Tt-e turbocharger failed and

limited tt-e diesel output to50% of full c~acity. Tt-erea::tor was at m