Text

Review of Brunswick Diesel Generator Tech Spec Improvement Study, Ltr Rept
	ML20205Q030
Person / Time
Site:	Brunswick
Issue date:	02/28/1987
From:	Fitzpatrick R; BROOKHAVEN NATIONAL LABORATORY
To:	; NRC
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ML20205P974	List: ML20205P968; ML20205P996; ML20205Q030;
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	CON-FIN-A-3837 GL-84-15, NUDOCS 8704030431
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2/20/87 4

(

REVIEW OF BRUNSWICK DIESEL GENERATOR TECHNICAL SPECIFICATION IMPROVEMENT STUDY I

R. Fitzpatrick LETTER REPORT February 1987 Department of Nuclear Energy Brookhaven National Laboratory Upton, New York 11973 h

Prepared for U.S. Nuclear Regulatory Commission Washington, DC 20555 j

Contract No. DE-ACO2-76CH00016 FIN A-3837 P* R88?u 889,

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-iii-i

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s TABLE OF CONTENTS I

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Page x

LI ST O F TAE LE S......................................................

t iv I.,

INTRODUCTION AND BACKGROUND...,...............................

1 II.

EVALUATIdN OF THE,CP&L PROBABILISTIC RISK-ANALYSIS............

6 i

II.A Methodology.............................................

6 II. B ' Ev e n t Se qu e n c e s....... '..................................

7 II.C-Su c ce s s Cri t e ria........................................

7

~

II.D Fault Trees..............................................

7 II.E Use of WAMCUT and FRANTIC 111...........................

8

_, II.F 1 Data....................................................

9

'II.G, Results............i..............'......................

10 i

T III.

SUMMARY

AND CONCLUSIONS.................................... 4.

20 IV.

REFERENCES....................................................

23 APPENDIX A:

NRC Ge n e ric Le t t e r 8 4-15...............................

A-1 APPENDIX B:

Proposed Technical Specifications for Brunwick-1 Dies el Gene rat or Ope rability.............'...............

B-1

. APPENDIX C:

Additional -Information in Support of the' BSEP Success Criteria...............................................

- C-1 4

4 f

k

]

t i

e 0

-iv-LIST OF TABLES i

Page I.1 Summary List of Revisions to BSEP Technical Specifications..

3 I.2 Diesel Generator Restoration Time Scheduled and Unscheduled Test and Maintenance........................................

5 11.1 Station Blackout Contribution to Core Damage Frequency in Recent BWR Studies..........................................

12 II.2 Decay Heat Removal Function Success Criteria Immediately After Reactor Trip..........................................

12 II.3 Diesel Generator Failure Combinations.......................

13 II.4 FRANTIC-III Te s t Configurations.............................

13 11.5 WAMCUT/ FRANTIC _III Component Definitions....................

14 II.6 FRANTIC III Input Summary for Case 1 - Loss of Of fsite Power.......................................................

15 II.7 FRANTIC III Input for Case 2 - Loss of Of fsite Power With LO CA i n On e Un i t............................................

16 II.8 WAMCUT Component Inputs for Reduced Fault Tree Models.......

16 II.9 Average Diesel Generator Unavailability Through 1984........

17 11.10 B S E P Dowe l Pin Failu r e Da t a.................................

17 11.11 DG Dowel Pin Wearout Analysis Results.......................

17 11.12 Relative Risk Analysis Resul ts..............................

18 II.13 Ave rage Annual Risk Analysis Results.........................

18 II.14 Sensitivity Analysis Results - DG Unavailability............

19.

II.15 Sensitivity to DG Weibull Scale Parcee'er...................

19 i

III.1 Manpower Requirements for BSEP Diesel Generator Scheduled Mai n t e nan ce Ac t ivi t i e s......................................

22 III.2 Diesel Generator Unscheduled Downtime.......................

22 l

1 l

I.

INTRODUCTION AND BACKGROUND This report provides the findings of an evaluation performed by Brook-haven National Laboratory (BNL) for the U.S. Nuclear Regulatory Commission.

l The subject of the evaluation was a submittal by Carolina Power and Light

-(CP&L) Company requesting approval of certain changes to the Technical Speci-fications of the Brunswick Steam Electric Plant (BSEP), Units 1 and 2.

CP&L has requested that the BSEP Technical Specification requirements be somewhat relaxed with respect to diesel generator testing during the periods defined as limiting conditions for operation. The underlying bases for this request include NRC Generic Letter No. 84-15 entitled, " Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability," specific diesel generator performance at BSEP and the desire by CP&L to reduce the pressure on the main-tenance crews to hurry with a diesel generator repair.

Generic Letter 84-15 (see Appendix A) addresses the results of diesel generator studies which definitely point to the premature wearout of diesel generator components due to the severe surveillance testing. required by current Technical Specifications. The letter further requests that operating license holders assess their own situations to determine what might be done to lessen the severity of diesel generator testing without compromising reactor plant safety.

The BSEP station consists of two nuclear generating units which share four diesel generators. The BSEP diesel generators have already experienced what appears to be essentially a common mode failure of dowel pins.

Ref. I states that:

" frequent testing of the diesel generators during the LCO condition can contribute to premature failures of diesel components due to wearout and cyclic fatigue mechanisms.

Specifically, common mode failure of one or more accessory pump dowel pins and cap screws in the flex drive coupling drive plate (LER 1-82-78) on all four diesels are believed to be a result of metal fatigue of the dowel pin material due to the excessive number of engine starts."

Therefore, this event provides CP&L with an even greater impetus than that provided by the generic letter for proposing meaningful changes to the BSEP Technical Specification testing requirements.

CP&L has addressed solutions to the task of upgrading diesel generator reliability in a comprehensive fashion that addresses three specific areas of concern. These three areas are (1) frequency of testing, (2) severity of testing, end (3) potential maintenance errors. This effort has been combined into a proposed set of new Technical Specifications. The proposed Technical Specifications for Unit 1 are incorporated as Appendix B (those for Unit 2 are identical). Appendix A includes the proposed set of Technical Specifications that were part of Generic Letter 84-15.

Table I.1 has been taken from Ref.1 and provides an item by item list of the proposed Technical Specification changes. The major changes include (1) the extension of the allowed outage time (A0T) of either an offsite power circuit or a diesel generator from three days to seven days, (2) the extension of time required to initially test the diesel generators during a limiting condition for operation ~(LCO) from within

i two hours to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , (3) the extension of time required for subsequently testing the diesel generators during an LCO from within each'

)

twelve hours to within each 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , and (4) to require'that the diesels be j

run with a significant load during the required testing.

The present BSEP Technical Specifications are in essential agreement with the Standard Technical Specifications in the areas discussed above. The bases and justification provided by CP&L in applying for the proposed changes are evaluated in Section II of this report. There is, however, one significant difference between the proposed Technical Specifications and NRC Ceneric Letter 84-15.

Current studies on diesel generators all point to the negative effects associated with running diesel engines without-load. The existing Technical Specification testing requirements call for running the diesels unloaded while testing during an LCO.

The proposed Technical Specifications include the requirement to load the diesel generators to at least 1750 kw for a minimum of fifteen minutes. CP&L points out that time is required to set up-such a diesel generator test in order to assure no perturbations to the reactor systems and that the existing Technical Specification testing frequencies do not provide significant time margins for executing such testing.

BNL concurs eith CP&L in that this new requirement to apply load is 4

a significant improvement over current testing procedures and that additional time to carry out such testing is a prudent request. The significant difference is that the generic letter suggested a minimum running time of one hour for the loaded diesel generator.

There are well founded technical bases for this one hour running time. The one hour allows the-diesel-to attain and run at its equilibrium temperatures which helps to assure complete and clean l

combustion. The CP&L report states that the intent would be to run for at least two hours.

It is BNL's recommendation that the required minimum running }

time be increased to at least the one hour value recommended by NRC Generic Letter 84-15.

Within the context and scope of the CP&L request, the " Typical Technical Specifications" found in NRC Ceneric Letter 84-15 are also in essential agreement with the Standard Technical Specifications. The major dif ference would appear to be that the "84-15" set suggests that license holders could apply for a Technical Specification change that would limit A0T on a yearly basis and not on an individual outage basis. However, the burden for supplying the required bases and justification is left to the license

{

holders. CP&L has elected not to pursue this latter concept.

In reviewing j

the BSEP diesel generator outage history and restoration times as shown in I

Table I.2 (Table A-6 from Reference 1), it can be seen that with few exceptions, the mean time to restore the diesel generators has been much less than the 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months already allowed. There is, therefore, no compelling reason or technical basis for CP&L to pursue this suggested alternative approach.

1 The CP&L proposed Technical Specification changes also include the relaxation of allowed outage time for an offsite power circuit from the present three days to seven days. This is consistent with'the proposed changes for the diesel generators. The CP&L analysis, however, has focused on the diesel generator changes and does not fully address the bases and justification for the proposed increase in the offsite power circuit A0Ts.

Therefore, this aspect of the CP&L Technical Specification change request is l

not included in this evaluation.

a Table I.1 Summary List of Revisions to BSEP Technical Specifications!

Page No.

Description 3/4 8-1 Section 3/4 8.1 has been reformatted to more closely resemble those pages provided in Generic Letter 84-15.

Former Action a has been divided into Action a, for an offsite circuit inoperable, and Action b, for a diesel generator inoperable.

Action a:

1.

Extended time requirement for performing Surveillance Requirement 4.8.1.1.2.a.4 (Diesel Quick-Start) from within two hours to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

2.

Surveillance Requirement 4.8.1.1.2.a.5 (Diesel Loading) added.

3.

Surveillance Requirement 4.8.1.1.2.a.4 (Diesel Quick-Start) interval lengthened from 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

4.

Extended the allowed outage time for an inoperable offsite circuit from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days.

Action b:

1.

Note added to clarify the definition of an inoperable diesel generator.

2.

Extended time requirement for performing Surveillance Requirement 4.8.1.1.2.a.4 (Diesel Quick-Start) from within two hours to within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3.

Surveillance Requirement 4.8.1.1.2.a.5 (Diesel Loading) added.

4.

Surveillance Requirement 4.8.1.1.2.a.4 (Diesel Quick-Start) interval lengthened f rom 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

5.

Extended the allowed outage time for an inoperable diesel generator from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 7 days.

3/4 8-2 Former Action b has been changed to Action c.

Action c:

1.

Surveillance Requirement 4.8.1.1.2.a.5 (Diesel Loading) added.

2.

Restoration of both offsite circuits and four diesel generators to operable status required within seven days from time of critical loss (consistent with Action a/b), previously limited to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

Table I.1 (Continued)

Description Page No.

Former Action c has been changed-to Action d.

Action d:

Surveillance Requirement 4.8.1.1.a.5 (Diesel Loading) added.

1.

2.

Restoration of second offsite circuits to operable status lengthened from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days (consistent with Action a).

Addition of " Cold Shutdown within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months " if 3.

at least one of inoperable offsite sources is not operable after going to Hot Shutdown.

Former Action d has been changed to Action e.

Action e:

Surveillance Requirement 4.8.1.1.a.5 (Diesel Loading) added.

1.

Addition of restoration of one diesel generator as required by 2.

Action b.

Restoration of fourth diesel generator to operable lengthened 3.

from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to seven days (consistent with Action b).

3/4 8-3 Note involving one time only exemption to Surveillance Requirement 4.8.1.1.2.d.3 deleted.

Note regarding start line added (pertaining to Surveillance Requirement 4.8.1.1.2.a.4).

Mathematical symbols < and > changed to phrases.

3/4 8-4 Note involving one time only exemption to Surveillance Requirement 4.8.1.1.2.d.7 deleted.

Mathematical symbol > changed to " greater than or equal to."

Table I.2 Diesel Generator Restoration Tine I

Scheduled and Unscheduled Test and Maintenance Mean Time to Restore DGf 1976 1977 1978 1979 1980 1981 1982 1983 1984a 1

14 55 15 18 17 8

12 14 27 2

7 25 2

17 28 7

10 16 0

e 3

9 13 21 12 21 15 14 43 37 4

d b

4 29 18 32 27 6

8 21 23 52 NOTES:

a: January-August.

b: Annual inspection took 117 hours0.00135 days 0.0325 hours 1.934524e-4 weeks 4.45185e-5 months and is excluded.

Annual inspection (46 hours5.324074e-4 days 0.0128 hours 7.60582e-5 weeks 1.7503e-5 months ), equipment modification (6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months ), and c:

problem with fuel injection for #1 cylinder (573 hours0.00663 days 0.159 hours 9.474206e-4 weeks 2.180265e-4 months ) are excluded.

d:

Scheduled maintenance on service water supply system (427 hours0.00494 days 0.119 hours 7.060185e-4 weeks 1.624735e-4 months ),

scheduled maintenance on preaction system (244 hours0.00282 days 0.0678 hours 4.034392e-4 weeks 9.2842e-5 months ), and scheduled maintenance on Woodward potentiometer (72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months ) are excluded. These events are assumed to have taken place under special NRC exemptions or when both units were shutdown.

s I

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- 6~-

EVALUATION OF THE CP&L PROBABILISTIC~ RISK ANALYSIS II.

The following subsections provide an evaluation of each of the najor portions of'the probabilistic risk analysis provided by CP&L as the bases and justification for their proposed Technical Specification changes for BSEP

- Units 1 and 2 as discussed in Section I above.

II.A Methodology' CP&L has performed certain analyses in support of their Technical Speci-f The methods employed in the analyses include a rela-fication change request.

tive risk method and an average annual risk comparison method.. This type of

)

apprcach is one of several addressed in NUREC/CR-3082 i

2

-The essence of the relative risk approach is simply that.if the risk during an j.

LCO can be shown to be less than some base (non-LCO)~ period, then the risk is The second part of the methodology,.the ' average annual deened acceptable.

risk comparison, follows directly from the first and is simply a convenient.

way of mapping the relative risks for each period of interest into a common The following. reasons baseline (in this particular case on a yearly basis).

were given by CP&L for choosing.the relative risk method:

It constrains the outage duration by requiring that the risk during the A0T be less than the risk during a baseline period.

h

. Insights are more clear when assessing risk on a relative basis rat er than on an absolute magnitude basis.

. The determination of the absolute limit of.the system average unavailability is not required.

The relative risk criterion as used by CP&L in this analysis can be defined by the following:

R0iRT where 0 = risk over the period of the outage of duration To.

i i

R T = risk over the baseline period T, assuming no outage.

R CP&L has defined risk for the purposes of their analysis to be the unavailability of onsite emergency ac power given either a loss of of fsite power transient or a LOCA coincident with a loss of offsite power.

BNL has reviewed the choice of the above two methods for their applica-bility to 'the subject Technical Specification change request.and concurs with

~

-No CP&L that these methods are applicable and relevant for the purpose.

J

However, deficiencies were found with the application of these methods.

exception is taken with the following statement within the report *

)

I "A preliminary investigation of the risk during an LCO and.

during a normal standby period indicates that current Technical Specifications may be overly restrictive and j

yield significantly lower results during LCOs than during the standby period."

i Y"*

F V

Tr s-q

~'#D-T^9-r e p-y, 97,9 is that the relative risk nethod does not The problem with the above statement address absolute risk (as discussed above) and therefore, cannot be used in' The above statement was not used as a basis for support of such statements.

any conclusion in the CP&L report and is simply noted here for its inconsis-tency.

II.B Event Sequences In order to apply the above methodology for determining acceptable risks, a directed probabilistic risk analysis was performed by CP&L on two basic (The basic parts of the probabilistic analysis are addressed event sequences.

in succeeding subsections.) The two event sequences chosen for the study were:

loss of offsite power for both Brunswick units, and

loss of offsite power for both units with a LOCA in one unit.

the The choice of these two sequences is particularly appropriate in that latter sequence encompasses the licensing basis for the two units (i.e., the design basis accident) and the former reflects the dominant core damage frequency contributor in most if not all of the la.est BWR PRAs and similar analyses.3-8 The Brunswick units do not have their own PRA, however, it is that station blackout would provide a similarly dominant reasonable to expect role here as it does in other similar plants. Table II.1 provides a listing of a number of current PWR studies ar.d the station blackout contributions determined therein.

II.C Success Criteria The success criteria are sequence-dependent for Brunswick Units 1 and 2 because the two units share four diesel generators and different combinations of diesel generators are required to successfully respond to a loss of effsite Table II.2 lists power and a loss of of fsite power concurrent with a LOCA.

the functional success criteria for the two event sequences and Table II.3 lists the corresponding diesel generator failure combinations. Appendix C l which evolve the Table provides the corresponding tables from the CP&L report II.3 findings.

BNL has reviewed the success criteria presented by CP&L includingWe have detailed analyses on decay heat removal as provided in keference 9.

concluded that the success criteria are appropriate for this analysis.

II.D Fault Trees The fault trees presented in the CP&L Technical Specification change request are simplified trees that were derived from NUREC/CR-29E9 " Reliability of Emergency AC Power Systems at Nuclear Power Plants.-10 Figure II.1 shows tree developed for Brunswick Units 1 and 2 from Reference the specific fault From this overall fault tree, CP&L created four simplified and specific 10.

trees for their analysis. Two of the trees address a loss of offsite power event and the other two address a loss of offsite power coincident with a LOCA The two trees for each category represent the in either Brunswick unit.

initial conditions for 1) no diesel generators unavailable and 2) a single diesel generator unavailable.

The fault tree simplification process utilized by CP&L was essentially the removal of the testing-and-naintenance-related gates fron the referer.ce fault tree. The service water system testing and maintenance contributions were not included due to their low contribution. This is consistent with and a result of the fault tree modelling approach used in Reference 10.

The diesel generator testing and maintenance contributions, although not included in the fault trees, were included as input to the FRANTIC III analysis (see Section II.E).

Thereappearstobeonemodellingerrorwhichiscomnontoallfourfault trees. According to the CP&L report, in order to use the. alternate de power source for each diesel, operator action is required to manually realign the de power sources.

This required action was not modelled.

In reviewing the quan-tified cutsets,Il provided in response to BNL's request for additional infor-mation, it was determined that this omission had no effect on the quantified results. The " missing" cutsets would be of the form "DC TRAIN X FAILURE

HUMAN ERROR" where, DC TRAIN X FAILURE represents the loss of the normal de source of diesel generator X control power and the HUMAN ERROR event represents the failure of the operator to manually realign the backup de-control power source. Given de train failure as 1E-4 (Table II.8) and the operator error as 0.5 (as an example), the quantification of these cutsets is at least two orders of magnitude below the derived event sequence results.

Based upon the above, we conclude that there are no significant deficien-cies with the fault tree modelling.

II.E Use of WAMCUT and FRANTIC III CP&L used the WAMCUT computer code to solve the fault trees discussed above and then used the FRANTIC III computer code to determine the time-dependent unavailabilities associated with each of three cases run for each event sequence. The three cases run for each event sequence were a baseline case, a case representing the existing LCO conditions, and the final case representing the proposed LCO conditions.

The baseline case was taken to be a 40 day interval in which all diesel generators are assumed to be available.

This particular interval was derived from plant-specific data which showed an overall mean time ~between failures of the Brunswick diesel generators to be about 1000 hours0.0116 days 0.278 hours 0.00165 weeks 3.805e-4 months .

Diesel generator testing frequency during the baseline case is assumed to be once per 31 days.

For second case, the testing interval is three days (the current allowed outage time for a single diesel generator) and this testing scheme reflects all three available diesels being tested within two hours and once per each 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter. The third case reflects the requested seven day allowed outage time with the testing scheme requiring all three available diesels to be tested within the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and once per each 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months thereaf ter.

Table II.4 provides a summary of these cases.

The FRANTIC III code was created specifically to handle system time-dependent unavailability as a function of failure rates, testing duration testing intervals, time to repair, test unavailability, and so on.

The input to this code must be in terms of an unavailability polynomial and conponent data reflecting the failure, testing, and maintenance characteristics noted above. FRANTIC III was designed to directly accept the output of the UAMCUT

- ~.

i '

code for the unavailability polynomial. Table II.5 lists the WAMCUT/ FRANTIC III component definitions used in.the analysis.

. Table II.6 provides a summary of the FRANTIC.III input data.for the three A similar table cases representing the loss'of offsite power event sequence.

(Table II.7) has been provided to show the input' data for the three cases 1

representing the loss of offsite power plus LOCA in one unit event sequence.

f.

2 1

In analyzing the. assumptions and input data' associated with the useiof the WAMCUT and FRANTIC III codes, BNL-has determined that the modelling and.

i assumptions adequately reflect the current and proposed testing schemes.- The i.

applicability of the input data is addressed in the following portion of.this report.

l.

II.F Data j

The BNL review and analysis of the input data used by CP&L in. support of

~

the subject Technical Specification change request focuses primarily on the This is because the remainder of the: data.

l diesel. generator wearout analysis.

used as input was taken directly from established and available data sources.

Table II.8 provides a listing of the basic events, their quantification, and the reference source.

CP&L did perform their own diesel generator-unavailability analysis using I

The overall results of this effort are listed in Table-j plant-specific data.II.9 and show that each of the four Brunswick diesel generators have p j

better than the data actually used from Table II.8.

4 As discussed in Section I, all four of the Brunswick diesel generators i.

have actually experienced a common failure mode that has been directly-attributed to the large number of severe-condition engine starts required.by Table II.10 provides a listing of the four. diesels and 4

current regulations.

the associated number of. starts to failure for each with respect to this i

This type of wearout phenomenon is usually characterized using

~

failure mode.

Accordingly, CP&L has used the WEIPLOT computer a Weibull distribution.

The to generate the parameters that describe -the observed f ailures.

12 4

code results of the CP&L dowel pin wearout analysis are shown in Table II.11.

As i

presented, these results represent the expected. mean time to f ailure of the I

dowel pins given the diesels are started every'12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months , every three days, and (CP&L maintenance practices j;

every 31 days assuming no preventive' maintenance.

are addressed in Section III.)

Appendix A of Ref. 1 provides a detailed description of how CP&L trans-4 formed their plant-specific failure data into'a characteristic distribution.

I.

The parameters of the distribution are derived to become additional input to l

The CP&L-derived standby failure l rate is a the FRANTIC III calculation.

f actor of five less than that presented in Ref.10. Although not investigated.

l' in detail, it appears that the difference lies in the fact that CP&L' excluded certain failures from their overall analysis (see the notes to Table.I.2).

The effects of these exclusions were'then addressed by CP&L with sensitivity Our evaluation of the sensitivity' studies is found:in Section~II.G.

[

studies.

i l

t

)

i II.G Results For Table 11.12 provides the results of the CP&L relative risk analysis.

both the loss of offsite power case and the loss of offsite power with a coin-cident LOCA in one unit case, the presented results satisfy the relative risk acceptance criterion in that the risks derived for the proposed Technical

. Specification requirements are less than those derived for the bas l

period.

basis.

In order to more fully substantiate the validity of the above cited results, CP&L performed two sensitivity studies on the loss of offsit sensitivity of the final results to the assumed diesel generator unavailabil-case.

It can clearly be seen that the calculated relative risks are directly proportional to the assumed diesel generator unavailability and in ity.

the base case.

The second sensitivity study is summarized in Table II.15 and shows the sensitivity of the final results to the choice of Weibull scale parameterAgain, the calc j'

(i.e., the assumed hourly standby failure rate).

for the proposed case do not exceed the risks calculated for the base case.

This particular case provides some additional insights that are directly The Weibull scale pertinent to the Technical Specification change request.

parameter is indicative of testing f requency within the given time period of As can be seen within the three and seven day LCO periods, there is interest.

really no measurable sensitivity to a significant change in scale parameter.

This leads directly to the conclusion that relaxing the diesel generator testing frequency during the three and seven day LCO periods does not have a 1

large impact on the calculated risk.

I

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Figure II.1 Brunswick i and 2 Fault Tree.10 (ORNL-DWG. 82-20506) f r

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Table II.1 Station Blackout Contribution to Core Damage l'

Frequency.in Recent BWR Studies Station Blackout Reference Plant-Contribution to CDF (%)

Study Peach Bottom 88 3 (ASEP) 1 Peach-Bottom 39-4 (IPE)

Grand Gulf 98 5 (ASEP)

Limerick 40 6 (FRA)-

Susquehanna 65 7 (IPE) 4 Shoreham

>20 8 (IPE) 2 Table 11.2 l

Decay Heat Removal Function Success Criteria l

Immediately After Reactor Trip j

1.

Main Condenser Available OR l

2.

RHR System in Suppression Pool Cooling Mode i

j OR

,3.

Reactor Depressurization to Cold Shutdown Entry Conditions AND l

3A.

RHR System in Shutdown Cooling Mode OR l

3B.

RHR with Fuel Pool Cooling Assist and RWCU System LOCA Mitigation j

Success Criteria i

f l

1.

RHR System in LPCI mode with two RHR pumps available.

l 2.

Core Spray System s(:h one core spray pump available.

l i

o i

m-,,_-

,..,,_,,---r,....-.

. ~.,

i Table II.3 I

Diesel Generator Failure Combinations I

DG Failures Consequences

]

Case 1: Loss of Of fsite Power /No LOCA 1 and 2 Loss of Heat Removal Capability in Unit 1 i

~

3 and 4 Loss of Heat Removal Capability in Unit 2 f

Case 2: Loss of Offsite Power With LOCA in One Unit-I and 2 Loss of Heat Removal Capability for Unit 1 1

OR Power Unavailable for ECCS cooling / makeup if LOCA occurs in j

Unit 1 3 and 4 Loss of Heat Removal Capability for Unit 2 i

OR j

Power Unavailable for ECCS cooling / makeup if LOCA occurs in Unit 2 j

1 and 4 Power Unavailable for ECCS cooling / makeup if LOCA occur.s in.:

Unit 1 or. Unit 2 l

2 and 3 Power Unavailable for-ECCS cooling / makeup if LOCA occurs in Unit 1 or Unit 2 5

Table II.4 j

FRANTIC-III Test Configurations 1

1 40 Day Standby 4

1 Test Interval - 31 days staggered bases Test Duration - Four hours (DG assumed to be loaded during test) 1 3 Day LCO (Baseline Case) 3i l

Test Interval - 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months i

Test Duration - 1/2 hour (Unloaded test)

Action Time - Testing starts within two hours.after LCO is initiated 7 Day LCO (Proposed Case) l Test Interval - 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months

]

Test Duration - Four hours (DG assumed to be loaded during test)

Action Time - Testing starts within 24. hours af ter LCO is initiated.

. _ - =

Table II.5 WAMCUT/ FRANTIC III Component Definitions I I

Component Name Component Definition LOFP Loss of Offsite Power Event LOCA 1 LOCA Event in Unit 1 LOCA 2 LOCA Event in Unit 2 DG1UD DG No.1 Unavailability DG2UD DG No. 2 Unavailability 2

DG3UD DG No. 3 Unavailability DG4UD DG No. 4 Unavailability SWCCF SW System Common Cause Unavailability DGCCF DG System Common Cause Unavailability BACCF DC Power System Common Cause Unavailability DGHEC DG Human Error Common Cause Unavailability DCIUD-Unit 1 DC Power System Unavailability DC2UD Unit 2 DC Power System Unavailability SWlUD Unit 1 SW System Unavailability SW2UD Unit 2 SW System Unavailability m

Table II.6 FRANTIC III Input Summary for Case 1 Loss of Offsite Power A.

Initiating Event (s)

Residual Unavailability Component Name 365 Days 40 Days 7 Days 3 Days LOFP 1.0E-2 1.1E-3 1.9E-4 8.2E-5 B.

Support Systems and Common Cause Components Component Name Residual Unavailability-SWCCF 8.0E-5 DGCCF 1.5E-4.

BACCF 1.0E-5 SW1UD 2.0E-3 SW2UD 2.0E-3 DCIUD 1.0E-4 DC2UD 1.0E-4 DGHEC 2.0E-4 C.

Diesel Generator Components 40 Day Standby Weibull Test First Time For Component Scale Interval Interval Testing Residual Name Parameter (Days)

(Days)

(Hours)

Unavailability DG1UD 1.03E-4 31 8.3E-2 4

5.0E-2 DG2UD 1.03E-4 31 7

4 5.0E-2 DG3UD 1.03E-4 31 14 4

5.0E-2 i

DG4UD 1.03E-4 31 21 4

5.0E-2 i

3 Day LCO DGIUD 1.03E-4

.5 8.3E-2

.5 5.0E-2 DC2UD 1.03E-4

.5 8.3E-2

.5 5.0E-2 DG3UD 1.03E-4

.5 8.3E-2

.5 5.0E-2 7 Day LCO DG1UD 1.03E-4 3

1 4

5.0E-2 DG2UD 1.03E-4 3

1 4

5.0E-2 DG3UD 1.03E-4 3

1 4

5.0E-2 Table II.7 FRANTIC III Input for Case 2 I

Loss of Of fsite Power with LOCA in One Unit A.

Initiating Event (s)

Residual Unavailability Component Name 365 Days 40 Days 7 Days 3 Days LOFP 8.8E-2 9.6E-3 1.7E-3 7.2E-4 LOCA 1 1.4E-3 1.5E-4 2.7 E-5 1.2E-5 LOCA 2 1.4E-3 1.5E-4 2.7E-5 1.2E-5 B.

Support Systems and Common Cause Components Same as in Case 1, Table II.6.

C.

Diesel Generator Components Same as in Case 1, Table II.6.

Table II.8 WAMCUT Component Inputs for Reduced Fault Tree Models I

i Component Name Unavailability Source Reference LOFP (Note 1) 13 LOCA1 (Note 1) 14 LOCA2 (Note 1) 14 DG1UD 5.0E-2 15 DG2UD 5.0E-2 15 DG3UD 5.0E-2 15 DG4UD 5.0E-2 15 SWCCF 8.0E-5 10 DCCCF 1.5E-4 10 BACCF 1.0E-5 10 DGHEC 2.0E-4 10 DCIUD 1.0E-4 10 DC2UD 1.0E-4 10 SW1UD 2.0E-3 10 SW2UD 2.0E-3 10 Note 1: For initiating events such as Loss of Offsite Power or a Loss of Coolant Accident, the probability of the event occurring was determined by determining the fraction of time applicable to the given period of interest and multiplying the yearly value accordingly.

i

Table II.9 I'

' Average Diesel Generator Unavailability Through-1984 I

-Average Unavailability DG#

for 8-Year Period i

I 1.8-2 2

1.1-2 l

3 2.3-2 i

4 1.6-2 j

-i k

I Table 11.10 l

BSEP Dowel Pin Failure Data Diesel Number of Generator Diesel Starts Number to Failure 1

1230 2

1659 3

1492 4

1494-Table 11.11 I

DG Dowel Pin Wearout Analysis Results Weibull Slope Standard Characteristic Testing or Shape HTTF Deviation Life

-Correlation Interval Parameter (Days)

(Days)

Coefficient 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months 8.6 681 94 720

.90 3 days 7.7 4382 670 4661

.96 31 days 7.7

.45286 6226 48164

.96 i

i -

{L,

Table 11.12 Relative Risk Analysis Results*I i

l Avg / Max Risk Avg / Max Risk Avg / Max Risk Over The Over The Over The Period of The Period of The -Period of The 1-Initiating Plant 3-Day LCO 7-Day LCO 40-Day LCO Event Risk (Current)

(Proposed)

(Baseline) l Loss of Off-AC Power Unavail-4.38E-6/

1.067E-5/-

1.37E-5/

site Power able ' for Decay 4.43E-6 1.19E-5 2.14E-5 (Case 1)

Heat Removal in Unit 1 or Unit 2 Loss of Off-AC Power Unavail-1.84E-9/

1.03E-8/

7.07E-8/

site Power able for Decay 1.86E-9 1.lE-8 1.086E-7 With LOCA in Heat Removal or One Unit

~For LOCA Mitiga-(Case 2: FSAR tion Design Basis)

Risk values are relative and do not reflect such things as recovery actions.

i Table II.13 Average Annual Risk Analysis Results*I Average Annual Average Annual i

Risk With Risk With J

Initiating Plant 3-Day LCO 7-Day LCO Event Risk (Current)

(Proposed) i i

Loss of Off-AC Power Unavailable For 1.5E-4 1.9E-4 site Power Decay Heat Renoval in (Case 1)

Unit 1 or Unit 2 f

Loss of Off-AC Power Unavailable For 7.4E-6 9.2E-6 site Power Decay Heat Renoval or For With LOCA in LOCA Mitigation l

One Unit (Case 2: FSAR i

l Design Basis) l

)

Risk values are relative and do not reflect such things as recovery actions.

J I

i

y-c.

,... -., ~., _,...

Table 11.14 Sensitivity Analysis Results l

f.

DG Unavailability l

Avg / Max Risk Avg / Max. Risk Avg / Max. Risk -

Over The Over The Over The DG Period of The Period of The-Period of The Unavailability 3-Day LCO 7-Day LCO 40-Day Standby 2.0E-2 1.76E-6/1.81E-6

4. 59E-6/ 5. 31E-6 5.8E-6/1.11E-5 4.0E-2 3.49E-6/3.54E-6 8.61E-6/9.35E-6 1.07E-5/1.76E-5 5.0E-2 4.38E-6/4.43E-6 1.067E-5/1.14E-5 1.37E-5/2.14E-5 6.0E-2 5.28E-6/5.33E-6 1.28E-5/1.35E-5 1.7 2E-5/ 2.56E-5 8.0E-2 7.13E-6/7.18E-6 1.7E-5/1.78E-5 2.53E-5/3.51E-5 l

1 l

l Table 11.15 l

]

Sensitivity to DG Weibull Scale Parameter Avg / Max Risk Avg / Max Risk Avg /Hax Risk DG Over The Over The Over The Weibull Scale Period of The Period of The Period of The Parameter 3-Day LCO 7-Day LCO 40-Day Standby

.i

)

1.03E-4 4.38E-6/4.43E-6 1.067E-5/1.14E-5 1.37E-5/2.14E-5 1

2.0E-4 4.4 3E-6/4. 53E-6 1.13E-5/1.27E-5 2.39E-5/4. 37E-5 1

4.0E-4 4.52E-6/4.72E-6

'1.25E-5/1.54E-5 5.17E-5/1.07E-4 6.0E-4 4.62E-6/4.92E-6 1.38E-5/1.81E-5 8.64E-5/1.85E-4

]

Note: Risk values are relative and do not reflect such things as recovery actions.

)

I i

i

{

1 1

i

.. -.. -.,.. -., - - - ~.

~ _. -

(

III.

SUMMARY

AND CONCLUSIONS The purpose of this section of the report is to summarize and integrate i

the individual findings from each of the subsections of Section II and to provide BNL's overall conclusions with respect to the CP&L Technical i

Specification change request. To that end, this section will:

I summarize-the adequacy of the assumptions', analyses, results,'and e

[

conclusions of the CP&L study, provide an assessment as to whether the proposed Technical 3 -

l Specifications actually reflect the Technical Specification changes derived from the results of the CP&L' study, j

summarize the benefits and risks of implementing the proposed Technical Specification changes, and i

. provide BNL's overall conclusions based upon the results of this review.

In integrating the findings of the individual analyses documented in l

i Section II, none of the discrepancies found-would have had any significant effect on the results and conclusions as presented by CP&L.-

We find that the proposed Technical Specification changes are indeed, j

vith two exceptions, supported by'the results of the CP&L analysis and are -

l additionally bpistered by the results of the BNL review which included a j

detailed review 'of the BSEP diesel generator overall_ maintenance _ program..II

~~

i The first exception, as discussed in Section I, is the minimum time

}

j requirement for testing the diesel generators under load during an LCO. The i

CP&L request to change the Technical Specifications to require that the

{

diesels be loaded during the testing is an irrefutable positive step. This is strongly encouraged by many NRC reports and especially, in this context, NRC Generic Letter 84-15 and it has a well founded and accepted technical basis.

However, BNL does recommend that the minimum required length of the test be f '

I one hour, in accordance with Generic Letter 84-15, and not the 15 minutes l

proposed in the CP&L Technical Specification change request. With respect to the request for an increased surveillance testing interval, our conclusions documented in Section II.C show that for the specifics of the BSEP diesel generators, the relaxation of calculated risk was not sensitive to the

/

surveillance testing intervals in both the three-day LCO and the seven-day LCO /

i cases.

i The second exception, as also discussed in Section I, relates to the request to extend the A0T for an offsite power' circuit from three days to

/

seven days. The bases and justification to support this portion of the Technical Specification change request were not fully documented in the CP&L i

I analysis and therefore no conclusions are offered in this report on that subject.

The requested change in allowed outage time for the diesel generators from three days to seven days provides only an incremental increase in risk.

I The bases for this conclusion are found in Tables III.1 and III.2.

Table 111.1 has been taken from Reference 1 and provides a listing of the BSEP die-i sel generator maintenance procedures and experience-based durations.

It is noted that none of the procedures exceed the present 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months allowed outage time limit. Table III.2, again taken from Reference 1, shows the yearly cumu-i i

lative duration of downtime for each of the four diesel generators.

Therefore, based upon the actual BSEP experience to date, the additional four days of requested allowed outage time would not be expected to be used on any frequent basis. CP&L has noted that the increased time would take the pressure off their maintenance crews in that they would not feel hurried.

BNL concurs with this conclusiod that pressure on the maintenance personnel would be reduced and, in addition, does not contemplate that the maintenance activities will become measurably longer than now being experienced. This latter aspect is seen as a risk improvement.

The basic benefits associated with adopting the proposed Tecc.nical Specifications changes art (1) less wear and tear on the diesel generators, (2) considerably enhanced operating flexibility for BSEP management, and (3) a less stressful work environment for BSEP maintenance personnel. The major risk associated with the proposed changes is the potential of operating with a diesel unavailable at any given time for up to seven days as opposed to the current three days.

In conclusion, we have found the technical merits of the proposed Technical Specification changes to be sound and well founded. We have found the relative risk approach to be an appropriate method of analysis and we concur with the results of that analysis in that the proposed changes pose less risk than that associated with the normal baseline period (i.e., the relative risk criterion has been met).

In addition, based upon our review of the diesel generator maintenance program,Il we have seen that CP&L has taken f steps in an attempt to remove the dowel pin failure mode by requiring specific inspections on a 6001100 start basis (which is less than one half the number of observed starts required for that failure mode).

Therefore, based upon our review documented herein, we recommend the approval of the CP&L Technical Specification change request subject to the resolution of our comment on the minimum required duration of diesel generator testing (proposed Technical Specification Item 4.8.1.1.2.a.5) and the extended AOT for the offsite power circuits (proposed Action a Section 3/4.8.1).

l

k..

Table 111.1 Manpower Requirements for BSEP Diesel Generator-Scheduled Maintenance Activities I No. of Hours

~No. of No. of 12 Procedure to Complete Maintenance Hour Shifts Number Description Frequency Work Personnel Per Day PT-12.3.1-Emergency 18 mo.

60 10 2

Diesel Inspection MI-10-503C Dowel Pin Every 6001 70 10 2

Inspection 100 Starts PT-12.3.5a DG. No.1 54 mo.

60 10 2

Inspection PT-12.3.5b DC. No.2 54 mo.

60 10 2

Inspection l

PT-12.3.5c DG. No.3 54 mo.

60 10 2

Inspection PT-12. 3. 5d DG. No.4 54 mo.

60 10 2

Inspection MI-10-503D DG Exhaust As required 12 6

1 Inspection on schedule Table 111.2 Diesel Generator Unscheduled Downtime l Mean Time to Restore DGi 1976 1977 1978 1979 1980 1981 1982 1983 1984*

1 27 11 1

105 24 2

31 31 2

20 29 4

6 12 68 3

35 32 32 52 105 4

1 50 77 24 168

January-August.

IV.

REFERENCES j

1.

Letter from A. B. Cutter (CP&L) to D. B. Vassallo (NRC), Request for License Amendment - Diesel Generator Operability, with enclosures, June 28, 1985.

2.

Lofgren and Vancolik, "Probabilistic Approaches to LCOs and Surveillance Requirements for Standby Safety Systems," NUREC/CR-3082.

3.

A. Kolaczkowski et al., " Reference Plant Accident Sequence Likelihood Characterization: Peach Botton, Unit 2," (Draft) NUREG/CR-4550 Volume 3, April 24, 1986.

4.

" Individual Plant Evaluation Method Applied to Peach Bottom Atomic Power Station," Philadelphia Electric Company, May 1986.

5.

M. T. Drouin et al., " Analysis of Core Damage Frequency Fron Internal Events: Grand Gulf Unit 1," (Draft) NUREG/CR-4550/6 of 10, July 1986.

6.

Probabilistic Risk Assessment, Limerick Generating Station, Philadelphia Electric Company, September 1982.

7.

" Individual Plant Evaluation Method Applied to Susquehanna Steam Electric Station," P. R. Hill et al., January 1986.

8.

" Individual Plant Evaluation Method Applied to Shoreham Nuclear Plant,"

Long Island Lighting Company.

9.

Gaontner et al., NSAC/83, " Brunswick Decay Heat Removal Probabilistic Safety Study," December 1984.

10. Battle and Campbell, " Reliability of Emergency AC Power Systems at Nuclear Power Plants," NUREG/CR-2989, July 1983.

11. Letter from S. R. Zimmerman (CP&L) to D. Muller (NRC), " Supplement to Request for License Amendment for BSEP - Diesel Generators (Generic Letter 84-15), September 2, 1986.

12. Weibull Failure Distribution Analysis and Plotting System, EPRI EM-3658-CCM, October 1984.

13. H. Wyckof f, " Losses of Offsite Power at Nuclear Power Plants," May 1984, NSAC/EPRI.

14. WASH-1400, " Reactor Safety Study," USNRC, October 1975.

15. NRC Generic Letter 84-15 " Proposed Staf f Actions to Improve and Maintain Diesel Generator Reliability," July 1984.

i

}

APPENDIX A: NRC Ceneric Letter 84-15 t

e I

A-1.

'/

UNITED STATES

,.. A

y. g,,

NUCLEAR REGULATORY COMMISSION

'f.

J WASHINGTON. D. C. 20555

/

July 2, 1984 TO ALL LICENSEES OF OPERATING REACTORS, APPLICANTS FOR AN OPERATING LICENSE, AND HOLDERS OF CONSTRUCTION PERMITS 1

4 Gentlemen:

SUBJECT:

PROPOSED STAFF ACTIONS TO IMPROVE AND MAINTAIN j

DIESEL GENERATOR RELIABILITY (Generic Letter 84-151-J I

As part of the proposed techriical evaluation of Unresolved Safety Issue (US-I) i A-44, Station Blackout, the staff is considering new requirements that would-

)

' reduce the risk of. core damage from station blackout events. The reliabil.ity i

of diesel generators has been identified as being one of the main factors affecting the risk from station blackout. Thus attaining and maintaining high l

reliability of diesel generators is a necessary, input to the resolution of USI j

A-44.

~

i Plants license.d since 1978 have been required to meet the reliability. goals of Regulatory, Gyide 1.108 for their diesel generators.

Howevir, the staff has determined that kny operating plants do not have r.eliability goals 'in place

[

for their diesel generators. Considering the critical role diesel generators play in mitigating various transients and postulated events following a loss of offsite power, the staff'has detennined that there is an important need to assure that the reliability of diesel generators at operating plants is

" maintained at an' acceptable level. The staff has deterinined that the risk-i frcm station blackout is such that early actions to improve diesel generator i

. reliability would have a significant safety benefit. Toward this objective

. we have developed the following approach to assess and enhance, where necess,ary,'

i i

.the reliability of diesel generators at all. operating plants.

l The items covered by this letter fall into the following three areas:

l

, 1.

Reduction in Number of Cold Fast Start Surveillance Tests for Diesel Generators i

This item is directed towards reducing the number of cold fast start suryeillance tests for diesel generators which the staff has detennined -

results in premature diesel engine degradation.

The details relating to I

this subject are provided in Enclosure 1.

Licensees are requested to describe their current programs to avoid cold. fast start surveillance testing or their intended actions to reduce cold fas't start surveillance testing for diesel generators.

j 2.

Diesel Generator Reliatiility Data This item requests licensees to furnish the current reliability of l

each diesel generator at their plant (s), based on surveillance test data.

Licensees are requested to provide the infonnation requested in.

q!

g.

84o7o20206

A-2

._ 3.

Diesel Generator Reliability Licensees are requested to' describe their program, if any, for attaining and maintaining a reliability goal for their diesel generators.

An example of a performance Technical Specification to support a desired diesel generator reliability goal has been provided by the staff in Enclosure 3.

Licensees are requested to comment on, and compare their existing. programs or any proposed program with the example performance specification.

Accordingly, pursuant to 10 CFR 50.54(f), operating reactor licensees are requested to furnish, under oath or affirmation, no later than 90 days from the date of this letter, the information requested in Items 1 through 3 above.

Applicants for operating licenses and holders of construction permits are not required to respond. _

Licensees may request an extension of time for submittals of the required information. Such a request must set forth a proposed schedule and justification for the delay. Such a request shall be directed to the Director, Division of Licensing, NRR. Any such request must be submitted no later than 45 days from the date of this letter.

-s This request for information has been approved by'the Office of Management and Budget under Clearance Number 3150-0011, which expires April 30, 1985.

'rq Sincerely, Original sig'ned by Darre11 G. Eisenhut Darrell G. Eisenhut, Director (yy!l Division of Licensing

" ~ '

..i. ;

Enclosures:

DISTRIBUTION 1.

. Reduction in Number of Cold Central File

[ '.'. ' ' -

Fast Starts for Diesel ORAB Rdg Generators

~~

CPatel 2.

Diesel Generator Reliability JZwolinski Data GHolahan 3.

Diesel Generator Reliability FMiraglit.

DEisenhut PHpngerbuhler(BT578) s s

D w,

n

-,-m n

r

$l zA -

c i,

i Et! CLOSURE 1 i

REDUCTION IN NUMBER OF COLD FAST START SURVEILLANCE TESTS FOR DIESEL GENERATORS t

j Fast Start Testino The staff has for sometime had under review and assessment methods of diesel ger.erator testing. The staff has determined that many licensees use a method-i of testing which does not take into consideration those manufacturer recomended preparatory actions such as prelubrication of all moving parts and warmup procedures which are necessary to reduce engine wear, extend life and improve availability. The existing Standard Technical Specifications recuire fast starts

' from ambient conditions for all surveillance testing which in many engine' designs

}

and operating practices subject the diesel engine to undue wear and stress on engine parts. Concerns were expressed by ACRS regarding the imposition of severe mechanical stress and wear on the diesel engine due to frequent cold fast starts...

Nuclear Industry related groups (INPO and American Nuclear Insurer) have also expressed concern based on operating experience that cold fast start testing l

results in incremental degradation of diesel engines and that, if proper.

procedures covering warmup prelubrication, loading / unloading etc., were taken, an improvement in reliability and availability would be gained. Similar views have beeg i,dgntified by the nuclear power industry and the regulatory authority 4

in Sweden. The authority in Sweden has taken corrective actions to reduce the

_t frequency of fast starts.

[

It is the staff's technical iudgement that an overall improvement in diesel engine reliability and availability can be gained by performing diesel generator starts for surveillance testino using engine prelube and other manufacturer 4

recommended procedures to reduce' engine stress and wear. The staff has also determined that the demonstration of a fast start test capability for emergency j

t diesel generators from ambient conditions cannot be totally eliminated because i

the design basis for the plant, i.e;, large LOCA coincident with loss of j

offsite power, require such a capability.

j In view of the above, the t.Laff has concluded that the frequency of fast start 1

4 tests from ambient conditions of diesel generators should be reduced. An example of an acceptatle Technical Specification to accomplish this goal is provided in the attachmer,t to this enclosure. Licensees are requested to describe their

]

current programs to avoid cold fast -starts or their intended action to reduce l

the number of cold fast start surveillance tests from ambient conditions for die,el generators. Licensees are encouraged to submit changes to their Technical Specification to accomplish a reduction in the number of such fast starts.

_0ther Testing Also, the staff is. concerned regarding a number of additicral diesel generator tests that are currently being ' required by Technical Specifications for some of-the earlier licensed operating plants.

For example, when subsystems of the i

emergency core cooling system on some plants are declared inoperable, the diesel i

generators are required to be tested. The staff has concluded that excessive-testing results in degradation of diesel engines.

In order to make those few plants consistent with the majority of the plants,;it is the staff's pnsition that the requirements for testing diesel generaters while emergency core cooling equipment is inoperable, be deleted from the Technical Specifications for such ii' plants. The affected licensees are encouraged to propose Technical Specifications to make such changes.

l

A-4

.iTTACEiENT TO E.'iCLOS'JRE 1 TYPICAL TECHNICAL SPECIFICATION SURVEILLANCE REOUIREMENTS j

4.5.1.1.1 Each of the above required independent circuits between the offsite transmission network and the onsite Class 1E distribution system shall be:

Determined ' OPERABLE at least once per 7 days by verifying a.

correct breaker alignment, indicated power availability, and j

b.

Demonstrated OPERABLE at least once per 18 months during shutdown by transferring (manually and automatically) unit i

power supply from the normal circuit to the alternate circuit.

4.8.1.1.2 Each diesel generator shall be demonstrated OPERABLE:

In accordance with the frequency specified in Table 4.8-1 on a a.

STAGGERED TEST BASIS by:

1.

VenYping the fuel level in the day and engine-mounted fuel tank.

l 2.

Verifying'the fuel level b the fuel storage tank,

~

3.

Verifying the fue1 transfer pump starts and transfers fuel from the storage system to the day and engine-mounted tank, 4

Verifying the diesel starts from ambient condition and i

accelerates to at least (900) rpm in less than or equal to 10 seconds.* The generator voltage and frequency shall be (4160)

(420) volts and (60)

(1.2) Hz within (10)* seconds after the start signal. The diesel generator shall be started for this test by using one of the following signals:

a)

Manual b)

Simulated loss of offsite power by itself.

The diesel generator start (10 sec) from ambient conditions shall be performed at least once per 184 days in these surveillance tests.

All t

other engine starts for the purpose of this surveillance testing may be preceded by an engine ~ prelube period and/or other warmup procedures recomended by the manufacturer so that mechanical stress and wear on the diesel engine is minimized.

NOTE: Bars in the margin show changes made to the Standard Technical Specifications.

. u

A-5 s.

SURVEILLANCE REOUIREMENTS (Continued) l c )'

Simulated loss o~f'offsite power in conjunction with an ESF actuation test signal.

d)

An ESF actuation test signal by itself.

5.

Verifying the generator is synchronized, loaded to greater than or equal to (continuous rating) in less than or equal to

(

) seconds,* and operates with a load greater than or equal to (continuous rating) for at least 60 minutes, 6.

Verifying the diesel generato'r is aligned to provide standby power to th,e associated emer'gency busses.

b.

At least once per 31 days and after each operation of the diesel where the period of operation was greater than or equal to I hour by. checking for and removing accumulated water from the day and.

engi6J-mounted fuel tanks.

c.

At least once per 92 days and from new fuel oil prior to additional to the storage tanks by verifying that a sample obtained in accordance with ASTN-D270-1975 has a water and sediment content of less than or equal ~ to,05 volu6e percent and a kinematic viscosity 9 40'C of greater than or equaT to 1.9 but less than or equal to 4.1 when tested in accordance with ASTM-D975-77, and an impurity level of less than 2 mg. of insolubles per.100 ml. when tested in accordance with ASTM-D-2274-70'.

t d.

At least once per 18 months, during shutdown by:

1.

Subjecting the diesel to an inspection in accordance with 7

procedures prepared in conjunction with its manufacturer's recommendations for this class of standby service.

2.

Verifying the generator capability to reject a load of

, greater than or equal to (lar est single emergency load) kw while maintaining voltage at 4160)

(420) volts and frequency-at (60)

(1.2) Hz less than or equal to 75% of the difference between nominal speed and the overspeed trip setpoint, or 15% above nominal whichever is-less).

i 3.

Verifying the generator capability to reject a load of (continuous rating) kw without tripping.

The generator voltage shall not exceed (4784) volts during and following the load rejection.

See footnote on previous page i

....=

~

A-6 DICLOSURE 1 DIESEL GEllERATOR RELIABILITY DATA Tre reliability of diesel generators has been identified as one of the nair factors affecting the risk of core damage from station blackout..Thus, attainment and continued maintenance of high reliability for diesel cer.erators is necessary to the resolution of USI A 44.

To assist the staff in assessing

,i the current reliability of diesel generators at operatino plants, licensees are recuested to report the reliability of each diesel generator at their plant fcr its last 20 and 100 demands.

This should include the number of failures in the last 20 and 100 valid demands indicating the time history for these failures.

Licensees are requested to indicate whetner they raintain a record which itemizes s

the demands and failures experienced by each diesel ' generator unit, in the manner outlined in Reguldtory Guide 1.108 position C.3.a, for each diesel generator unit. Licensees should also indicate whether a yearly data report is maintained for each diesel generator's reliability. The criteria for determinino the reliability of diesel generators is as follows:

-g Valid demands and failures are to be determined in accordance a.

with the recommendations of Reculatory-Guide 1.108 position c.2.e.

b.

The reliability of each diesel generator will-be calculated based on the number of failures in the last 100 valid demands.

e G

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A-7 ENCLOSURE 3 DIESEL GENERATOR RELIARILITY In the staff's ongoing program to resolve USI A-44, Station Blackout, diesel generator reliability is ore of the factors used to determine the length cf time a plant should be able to cope with a station blackout.

If all other factors are constant, the higher reliability of the diesel generator will result in the lower probability of a total loss of AC power. Maintaining diesel generators at or above specific reliability levels is assumed in the development of the resolution of USI A-44.

The reliable operation of diesel generators should be assured by a reliability program designed to monitor, improve (if necessary), and maintain reliability at a specified level.

In view of the above, licensees are requested to describe their diesel generator reliability improvement program, if any, for attaining and maintaining a reliability goal. The program description should address the surveillance and testing the licersee performs to demonstrate the selected diesel generator reliability. All licensees have received the staff's previous letter trans-nitting the findings of NUREG/CR-0660, " Enhancement of Onsite Emergency Diesel Generator Reliebility, February 1979" identifying areas where diesel generator operational problems.were necurring in general. Licensees should consider the recommendations of NUREG/CR-0660 in their reliability program. The staf f has developed an example for a diesel generator performance Technical Specification to support the maintenance of diesel generator reliability at a specified l evel. The proposed performance specification encompasses certain aspects of the existing recuirements for surveillance testino of diesel oenerators stipulated in Regulatory Guide 1.108 and the qualitative recommendations of NUREG/CR-0660. This performance specification is presented, as an example, in the attachment to this enclosure. Licensees are requested to comment on and/or compare their program with the performance specification and provide comments for staff consideration in finalizing surveillance testing requirements for diesel generators.

O e

4 ene

A-8 ATTACHMENT TO ENCLOSURE 3 EXAMPLE OF DIESEL GEhERATOR PERFORMANCE TECHNICAL SPECIFICATION

Background

Review of LER data gathered as part of the staff's study of USI A-44, Station Blackout, indicates the median value of diesel generator reliability at operating plants to be 0.98/ demand with about 75% of diesel generators currently in service having a reliability of 0.95/ demand or greater. The following is an elaboration of the example perforrlance Technical Specification proposed to maintain reliability levels in this range:

Reliability Program 1.

Reliability Goals The staff's proposed resolution of USI A-44 currently under development would provide guidance for plants to maintain diesel generator reliability at or above specified levels (0.95 being the minimum desired level).

In order to assure that this level is achieved and maintained, a surveillance test program is necessary. t Based on surveillance testing, should a diesel generator's reliability fall below a specified level, certain actions should be taken as presented in the next section..

2.

Reliability Level Remedial Actions The reliability of each diesel generator is based on the number of failures in the last 100 valid demands, with appropriate remedial actions as follows. Note that "P" is defined as the probability of failure per demand per diesel.

PLANT GROUP RELIABILITY ACTION A

(1-p)1.95 Continue surveillance testing at 31 day interval.

Increase

~

surveillance testing.per Table 4.8.1 of Appendix A if the failures in the last 20 tests were h 2.

8

.95 '> (1-P).h 0.'90 Increase surveillance testing per Table 4.8.1 of Appendix A and take action per Table 4.8.2 of Appendix A.

C (1-P)d.90 Disqualify DG. Requalify DG in accordance with Table 4.8.2 Appendix A.

The diesel generator would remain inoperable from the time of the last failure through the period required for corrective action and until the first subsequent valid suc:essful test is completed.

A-9

.?.

3.

Surveillance Test Frequency In order to meet the timeliness goal, a normal test frequency is established and a criterion for increasing the test frequency is necessary to-determine whether a major degradation in reliability is indicated.

a.

Nomal plant surveillance - each diesel generator unit should be tested at a frequency which is in accordance with the manufacturer's recomendations, but in no case should the time between tests be greater than 31 days.

b.

Accelerated plant surveillance - whenever a diesel generator unit has experienced two or more failures in the last twenty demands, the maximum time between tests should be reduced to seven days. This test frequency should be maintained until seven consecutive failure-free demands have been performed and the number of failures in the last 20 demands has been reduced to one or less. Two failures in 20 demands is a failure rate of 0.1, or the threshold of acceptable diesel generator perfomance, and hence may be an early indieption of degradation of the reliability of a diesel generator. However, when considered in the light of a long history of tests, two failures in the last 20 demands may only be a statistically probable distribution of two random events.

Increasing the test frequency will allow for a more timely accumulation of additional test data upon which to base judgment of the reliability of the unit.

4.

Remedial Action Criteria If the number of failures in the last twenty valid tests is three or more or in the last 100 valid tests is six or more, the licensee should within 14 days prepare and maintain a report describing the reliability improvement program at the facility which includes, but is not limited to; 1) the implementation of NUREG/CR-0660 recomendations, and 2) perform a reliabilty assessment of the offsite and onsite power system.

(See Table 4.8.2 of Appendix A for details regarding action required).

5.

Requalification Criteria If the number of failures in the last twenty valid tests is five or more, or in the last 100 valid tests is 11 or more, the affected unit would be disqualified from nuclear. service and subjected to a requal-ification program.

A requalification program would be a series of 14 successful consecutive tests without a failure. The licensee would perfom seven consecutive successful demands without a failure within 30 days of the diesel generator being restored to operable status and 14 consecutive demands without a failure within 75 days of the diesel generator being restored to operable status. Refer to Attachment 2 to Table 4.8-2 of Appendix A for criteria. Two attempts would be allowed to achieve the acceptable test series. During requalification testing, a diesel generator unit would not be tested more frecuently than once in any 24-hour interval.

A-10

-3 6.

Failure to Recualify a Diesel Generator If the diesel generatur is rot requalified as defined above, the unit would be declared inoperable and the action statement in.the plant Technical Specification for one diesel generator inoperable should be followed imediately.

7.

Diesel Generator Inoperability Limits The staff has determined that the allowable out-of-service period for a diesel generator should be in excess of the current 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Technical Specification limit, while at the same time placing a yearly limit upon the total cumulative time that a plant may operate with one of the diesel generators inoperable. By placing an individual limit on maximum inoperable time for a diesel generator and a cumulative limit of inoperability of the onsite power system, a framework is established within which flexibility is provided to allow a licensee to best optimize planned and unplanned service of diesel generators at a plant.

This would limit plant risk from station blackout at the same time allowing flexibility for any given outage. Licensees may propose a total cumulative outage tine for diesel generators in the Technical Specification along with the basis for the outage t'pe chosen.

8.

Valid Demands and Failures Valid demands and failures used in the above paragraphs should be detemined in accordance with the recommendations of Regulatory Guide 1.108, position C.2.e.

9.

Reliability Records A record should be maintainec' in accordance with the recomendations of Regulatory Guide 1.108 position C.3.a for each diesel generator unit at a site which itemizes the demands and failures experienced by the diesel of Appendix A) generator unit. (See also Attachment -1 to Table 4.8.2 i

=

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A-11 APPENDIX A TYPICAL TECHNICAL SPECIFICATIONS 3/4.8 ELECTRICAL POWER SYSTEMS 3/4.8.1 A.C. SOURCES OPERATING LIMITING CONDITION FOR

_0PERATION 3.8.1.1 As a minimum, the following A.C. electrical power sources shall be OPERABLE:

Two physically independent circuits between the offsite a.

transmission network and the onsite Class 1E distribution system, and b.

Two separate and independent diesel generators, each with:

1.,. g Separate day and engine-mounted fuel tanks containing b

a minimum volume of gallons of fuel, 2.

A separate fuel storage sys'te'm containing a minimum volume of gallogs of fuel, and 3.

~A separate fuel transfer pump.

1 APPLICABILITY: MODES 1, 2, 3, and 4.

ACTION:

With an offsite circuit of the above required A.C. electrical a.

power sources inoperable, demonstrate the OPERABILITY of the remaining A.C. offsite source by performing Surveillance Requirement 4.8.1.1.1.a within I hour and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter; and Surveillance Requirement 4.8.1.1.2.a.4 within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ; restore at least two offsite circuits and two diesel generators to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months or be in at least HOT STANDBY within,the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

NOTE: The modified Standard Technical Specification is intended as an example of changes due to the reduction in number of fast starts and diesel generator reliability improvement program surveillance fiquirements. Bars in the margin show changes for those portions of technical specifications associated with these two items.

It is necessary for licensees to incorporate these changes into existing plant technical specification upon implementatinn of these two items.

L

A-12 ACTION:

(Continued) b.'

'With'a diesel generator of the above required A.C. electrical power sources inoperable,* demonstrate the OPERABILITY of the A.C. offsite sources by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter; and Surveillance Requirement 4.8.1.1.2.a.4 within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ; restore diesel generators to OPERABLE status within (A**) days *** or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months . At the number of failures for the inoperable diesel indicated in Table 4.8-2 perform the Additional Reliability Actions prescribed in Table 4.8-2 and its att,achments.

c.

With one offs.ite circuit and one diesel generator of the above required A.C. electrical power sources inoperable, demonstrate the OPERABILITY of the remaining A.C. offsite source by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months

.and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter and Surveillance

~ R#duirement 4.8.1.1.2.a.4 within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ; restore at least one of the inoperable sources to OPERABLE status within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30. hours. With the diesel generator r.estored to OPERABLE status, follow Action Statement

^

a.

With the offsite circuit restored to OPERABLE status, follow Actjan Statem nt b.

A diesel generator shall.be considered to be inoperable from the time of failure until it satisfies the requirements of Surveillance, Requirement 4.8.1.1.2.4 ELECTRIC POWER SYSTEMS

- The maximum time that an individual diesel generator may be inoperable (A) shall be established by the licensee based on the manufacturer's recommendations and previous maintenance and repair experience.

Every reasonable effort shall be made to restore individual diesel generators to operable status within that time period (A).

Every reasonable effort shall be interpreted to mean that diagnosis and repairs are to begin immediately and are to continue uninterrupted until the diesel generator is declared operable or an orderly retreat to cold shutdown is initiated.

- - The maximum total cumulative time that the diesel generators of the 1

onsite emergency AC power system may be in the INOPERABLE status in a given year shall be proposed by the licensee.

w w

A-13 ACTION:

(Continued) d.

With two of the above required offsite A.C. circuits ino'perable, demonstrate the OPERABILITY of two diesel generators by performing Surveillance Requirement 4.8.1.1.2.a.4 within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months unless the diesel generators are already operating; restore at least one of the inoperable offsite sources to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

With only one offsite source restored, follow Action Statement a.

With two of the above required diesel generators inoperable, e.

demonstrate the OPERABILITY of. two offsite A.C. circuits by performing Surveillance Requirement 4.8.1.1.1.a within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months c

and at least once per 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months thereafter; restore at least one of the inope'rable diesel generators to OPERABLE status within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUT 00WN within the 'following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months . With one

. d esel generator unit restored, follow Action Statement b and d

4 e

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m

A-14

..l SURVEILLANCE REOUIREMENTS 4.8.1.1.1 Each of the above required independent circuits between the offsite transmission network and the onsite Class IE distribution system shall be:

a.

Detemined OPERABLE at least once per 7 days by verifying correct breaker alignments, indicated power availability, and b.

Demoastrated OPERABLE at least once per 18 months during 4

shutdown by transferring (manually and automatically) unit power supply from the normal circuit to the alternate circuit.

4 4.8.1.1.2.g Each diesel generator shall be demonstrated OPERABLE:

a.

In accordance with the frequency specified in Table 4.8-1 on a STAGGERED TEST BASIS by:

1.

Verifying the, fuel lefel in the day and engine-mounted fuel

tank, 2.

Verifying the fuel level in the f,uel storage tank, 3.

Verifying the fuel transfer pump starts and transfers fuel from the storage system to the day and engine-mounted tank, 4

Verifying the diesel starts from ambient condition and accelerates to at least (900) rpm in less than or equal to 10 seconds.* The generator voltage and frequency.shall be (4160)

(420) volts and (60)

(1.2) Hz within (10) seconds after the start signal. The diesel generator shall be started for this test by using one of the following l

signals:

a) Manual b) Simulated loss of offsite power by itself.

The diesel generator start (10 sec) from ambient conditions shall be performed at least once per 184 days in these surveillance tests.

All other engine starts for the purpose of this surveillance testing may be preceded by an engine prelube period and/or other warmup procedures recommended by the manufacturer so that mechanical stress and wear on the diesel engine is minimized.

(

A-15 SURVEILLANCE REQUIREMENTS (Contined) c) Simulated loss of offsite power in conjunction with an ESF actuation test signal, d) An ESF actuation test signal by itself.

5.

Verifying the generator is synchronized, loaded to greater than or equal to (continuous rating) in less than or equal to ( ) seconds,* and operates with a load greater than or equal to (continuous rating) for at least 60 minutes, o

s 6.

Verifying.the diesel generator is aligned to provide standby power to the associated emergency busses.

b.

At least once per 31 days and after each operation of the

.di,elel where the period of operation was greater than or.

equdl to I hour by checking for and removing accumulated water from the day and engine-mount.ed fuel tanks.

~

c.

At least once per 92 days and from new fuel oil prior to addition to.the storage tanks by ve'rifying that a sample obtained in accordance~with ASTM-D270-1975 has a water and sediment content of less than or equal to.05 volume percent and a kinematic viscosity 0 40*C of greater than or equal to 1.9 but less than or equal to 4.1 when tested in accordance with ASTM-D975-77, and an impurity level of less than 2 mg.

of insolubles per 100 ml. when tested in accordance with ASTM-D2274-70.

d.

At least once per 18 months, during shutdown, by:

1.

Subjecting the diesel to an inspection in accordance'with procedures prepared in conjunction with its manufacturer's recomendations for this class of standby service.

2.

Verifying the generator' capability to reject a load of greater than or equal to (largest single emergency load) kw while maintai9ng voltage at (4160) : (420) volts and frequency at (60)

(1.2) Hz (less than or equal to 75% of the difference between nominal speed and the overspeed trip setpcint, or 15% above nominal whichever is k.ss).

1 3.

Verifying the generator capability to reject a load of (continuous rating) kw without tripping. The generator voltage shall not exceed (4784) volts during and following the load rejection.

5ee footnote on page 4 1

A-16 SURVEILLANCE REOUIREMENTS (Continued) 4.

Simulating a loss of offsite power by itself, and a) Verifying de-energization of the emergency busses and load shedding from the emergency busses.

b) Verifying the diesel starts on the auto-start signal, energizes the emergency (busses with permanently connected loads within

10) sei:onds, energizes the auto-connected shutdown. loads through the load sequencer and operates.for greater than or equal to 5 e

minutes while its generator is loaded with the shutdown loids. After energization, the steady state voltage and frequency of the emergency busses shall be i

maintainedat(4160)

(420)voltsand(60)

(1.2)Hz during this test.

....g 5

Verifying that on an ESF actuation test signal, without j

loss of offsite power, the diesel generator starts on the auto-sitart signal and operates on standby for greater than or equal to 5 minutes.

The genbrator voltage and frequency ~

i shall be'(4160)-

(420) volts and (60)

(1.2)Hzwithin (10) seconds.after the auto-start signal; the steady state generator voltage,and frequency shall be maintained within these limits during this test.

6.

Simulating a loss of offsite power in conjunction with an ESF actuation test signal, and a)

Verifying de-energization of the emergency busses and load shedding from the emergency busses.

b)

Verifying the diesel starts on the auto-start signal, energizes the emergency busses with permanently.

connected loads within (10) seconds, energizes the I

A-17 SURVEILLANCE REOUIREMENTS (Continued) auto-connected emergency (accident) loads through the load sequencer and operates for greater than or equal to 5 minutes while its generator is loaded with the emergency loads.

After energization, the steady state voltage and frequenc maintained at (4160)y of the emergency busses shall be (420) volts and (60) : (1.2)Hz during this test.

c) Verifying that $11 automatic diesel generator trips,

~

except engine overspeed and generator differential, are automatically bypassed upon loss of voltage on the emergency bus concurrent with a safety injection actuation signal.

I 7 i Verifying the diesel generator operates for at leas't 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . During the first 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of this test, the diesel generator shall be loaded to greater than or equal to (2-hour rating) kw and during the remaining 22 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months of this test, the diesel generator shall. be loaded to greater than or equal-to (continuous ratin and frequency shall be (4160)g) kw. The generator voltage (420)and(60)

(1.2)Hz within (10) seconds after the start signal; the steady state generator voltage and frequency shall be maintained within these limits during this test.

Within 5 minutes af ter completing this 24-hour test, perform Surveillance Requirement 4.8.1.1.2.d.7.b.

8.

Verifying that the auto-connected loads to each diesel generator do not exceed the 2000-hour rating of kw.

9.

Verifying the diesel generator's capability to:

a) Synchronize with the offsite power source while the generator is loaded with its emergency loads upon a simulated restoration of offsite power, b) Transfer its loads to the offsite power source, and c) 'Be restored to its standby status, i'

10.

Verifying that with the diesel generator operating in a test mode, connected to its bus, a simulated safety injection signal overrides the test mode by (1) returning the diesel generator to standby operation and (2) automatically energizing the emergency loads with offsite

power, i

,m+

7_,

3 7..

A-18

, ELECTRIC POWER SYSTEMS Table 4.8.1 DIESEL GENERATOR TEST SCHEDULE Number of Failure in Last 20 Valid Tests

Test Frequency

. e.

f;l At least once per 31 days

,. g 2r 2 At least once per 7 days **

~s iteria for determining number of failures and number of valid tests cr

~

shall be in accordance with RegulaVbry Position.C.2.e of Regulatory Guide 1.108, Revison 1, August 1977, where the number of tests and l

i failures is determined on a per diesel generator basis.

For the purposes of this test schedule, only valid tests conducted after the OL issuance date shall be included in the computation of the "last 20 valid tests."

*This test frequency shall be maintained until seven consecutive

. failure free demands have been performed and the number of

. failures in the last 20 valid demands has been reduced to one or less.

l

A-21 ATTACHMENT 2 TO TABLE 4.8-2 DIESEL GENERATOR REOUALIFICATION PROGRAM (1) Perform seven consecutive successful demands without a failure within 30 days of diesel generator being restored to operable

's status and fourteen consecutive successful demands without a failure within 75 days of diesel generator of being restored to

],

operable status.

(2)

If a failure occurs during the first seven tests in the requalification test program, perform seven successful demands without an additional failure within 30 days of diesel generator of being restored to operable status and fourteen consecutive successful demands without a failure within 75 days of being restored to operable status.

(3)

If a failure occurs during the second seven tests (tests 8 through

14) of (1) above, perform fourteen consecutive successful demands witnourg an additional' failure within 75 days of the failure which occurred during the requalification testing.

(4) Following the second failure during'the requalification test program, be in' at' least HOT STANDBY within. the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and COLD SHUTDOWN within the fol}owing 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

(5) During requalification. test.ing the diesel generator should not be tested more frequently than at 24-hour intervals.

After a diesel generator has been successfully requali'ied, subsequent i

repeated requalification tests will not be required for that diesel generator under the following conditions:

(a) The number of failures in the last 20 valid demand; is less than

~

5.

(b) The number of failures in the last 100 valid demands is less than 11.

(c)

In the event that following successful requalification of a diesel generator, the number of failures is still in excess of the remedial action criteria (a-and/or b above) ~the following exceptior will be allowed until the' diesel generator is no longer in violation of the remedial action criteria (a and/or b above).

Requalification testing will no.ti be required provided that after each valid demand the number of failures in the last 20 and/or 100 valid demands has not increased. Once the diesel generator is no longer in violation of the remedial action criteria above the provisions of those criteria alone will prevail.

APPENDIX B: Proposed Technical Specifications for Brunswick-1 Diesel Generator Operability l

B-1 (BSEP-1-43) 3/4.8 - ELECTRICAL PC'a*ER SYSTEMS 3/4.8.1 A.C. SOURCES OPERATION OF ONE OR BOTH UNITS LIMITING CONDITION FOR OPERATION 3.8.1.1 As a minimum, the following A.C. electrical power sources shall be OPERABLE:

a.

Two physically independent circuits between the offsite transmission network and the onsite Class IE distribution system, and i

b.

Four separate and independent diesel generators, each with:

{

1.

A separate engine-mounted fuel tank containing a minimum of 100 gallons of fuel, 2.

A separate day fuel tank containing a minimum of 22,650 gallons of fuel, and 3.

A separate fuel transfer pump.

c.

A plant fuel storage tank containing a minimum of 74,000 gallons of fuel.

APPLICABILITY: OPERATIONALI CONDITIONS 1, 2, and 3.

ACTION:

With an offsite circuit of the above required A.C. electrical power a.

sources inoperable', demonstrate the OPERABILITY of the remaining A.C.

offsite sources by. performing Surveillance Requirement 4.8.1.1.1.a within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and' at least once oer 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereaf ter; and demonstrate the OPERABILITY of the diesel generators by performing Surveillance Requirements 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5 within.

24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months thereafter; restore the inoperable offsite circuit to OPERABLE status within 7 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

b.

With a diesel generator of the above required A.C. electrical power sources inoperable,* demonstrate the OPERABILITY of the A.C. of fsite sources by performing Surveillance Requirement 4.8.1.1.1.a within i

2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereaf ter; and demonstrate the OPERABILITY of the remaining diesel generators by performing Surveillance Requirements 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5 within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and at least once per 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months thereaf ter; restore the inoperable diesel generator to OPERABLE status within 7 days or be in -

+

st least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

4 1

l

A diesel generator shall be considered to be inoperable from the time of f ailure until it satisfies the requirements of Surveillance Requirement 4.8.1.1.2.

BRUNSWICK - UNIT 1 3/4 8-1 Amendment No.

't r.

,, - y 3

y

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+,- -,,., - -, -

r--

y r.

.-,i--

B-2 (BSEP-1-43)

ELECTRICAL POWER SYSTEMS LIMITINC CONDITION FOR OPERATION (Continued)

ACTION (Continued) c.

With one offsite circuit and one diesel generator of the above required A.C. electrical power sources inoperable, demonstrate the OPERA 3ILITY of the remaining A.C. offsite source and diesel generators by performing Surveillance Requirements 4.8.1.'1.1.a,

[

4.8.1.1.2.a.4, and 4.8.1.1.2.a.5 vichin 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per i

12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereaf ter; restore at least one of the inoperable sources to CPERABLE status within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . With one A.C. power source restored, demonstrate the OPERASILITY of the remaining A.C. power sources as required,in ACTION a or ACTION b as applicable; restore two offsite circuits and four diesel generators to OPERABLE status within 7 days from the time of initial loss or be in HOT SHUTDOWN within the next.12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

d.

With two of the above required offsite A.C. circuits inoperable, demonstrate the OPERABILITY of four diesel generators by performing Surveillance Requirements.4.8.1.1.2.a.4 and 4.8.1.1.2.a.5 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereaf ter unless the diesel generators are already operating; restore at least one of the inoperable of f site sources to OPERABLE status within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTCOVN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . With one of fsite source restored, demonstrate the OPERABILITY of the remaining A.C. power sources as required by ACTION at restore two offsite circuits to OPERABLE status within 7 days from time of. initial loss or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

l l

e.

With two of the above required diesel generators inoperable.

demonstrate the OPERABILITY of the offsite A.C. circuits and the remaining diesel generators by performing Surveillance Requirements 4.8.1.1.1.a. 4.8.1.1.2.a.4 and 4.8.1.1.2.a.5 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereaf tert restore at least three diesel generators to OPERABLE status within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . With one diesel generator restored, demonstrate the OPERABILITY of the remaining A.C. power sources as required by ACTION bi restore four diesel generators to OTERABLE status within 7 days from time of initial loss or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

BRUNSWICK - UNIT 1 3/4 8-2 Amendment No.

B-3 (BSEP-1-43).

ELECTRICAL POWER SYSTEMS SURVEILLANCE REQUIREMENTS 4.8.1.1.1 Each of the above required independent circuits between the offsite transmission network and the onsite Class 1E distribution system shall bet Determined OPERABLE at least once per 7 days by verifying correct s.

breaker alignments and indicated power availability, and b.

Demonstrated OPERABLE at least once per 18 months during shutdown by manually transferring unit power supply from the normal circuit to the alternate circuit.

4.8.1.1.2 Each diesel generator shall be demonstrated OPERABLE:

At least once per 31 days on a STACCERED TEST BASIS by:

a.

1.

Verifying the fuel level in the engine-mounted fuel tank, 2.

Verifying the.uel level in the day fuel tenk,

~

3.

Verifying the fuel transfer pump can be started and transfers fuel from the day tank to the engine mounted tank, 4

Verifying the diesel starts and accelerates to at least 514 rpm in less than or equal to 10 seconds

5.

Verifying the generator is synchronized, loaded to greater than or equal to 1750 kw, and operates for greater than or equal to 15 minutes, and 4

6.

Verifying the diesel generator is aligned to provide standby power to the associated emergency buses.

b.

At least once per 31 days by verifying the fuel level in the plant fuel storage tank.

At least once per 92 days by verifying that a sample of diesel fuel c.

from the fuel storage tank, obtained in accordance with ASTM-D270-65, is within the acceptable limits specified in Table 1 of ASTH-D975-74 when checked for viscosity, water and sediment, 3

The diesel generator start (10 seconds) from ambient conditions shall be performed at least once per 184 days in these surveillance tests. All other engine starts for the purpose of this surveillance testing may be preceded by a manually initiated engine prelube period and/or other warmup Procedures recommended by the manufacturer so that mechanical stress and wear on the diesel engine is minimized.

BRUNSWICK - UNIT 1 3/4 8-3 Amendment No.

J

B-4 (BSEP-1-43)

ELECTRICAL POWER SYSTEMS SURVEILLANCE REQUIREMENTS (Continued) d..

At least once per 18 months during shutdown by:

i 1.

Subjecting the diesel to an inspection in accordance with procedures prepared in conjunction with its manufacturer's recommendations for this class of standby service, 2.

Verifying the generator capability to reject a load equal to one core spray pump without tripping, 3.

Simulating a loss of offsite power in conjunction with an l

emergency core cooling system test signal, and:

a)

Verifying de-energization of the emergency buses and load shedding from the emergency buses.

b)

Verifying the diesel starts from ambient condition on the' auto-start signal, _ energizes the emergency buses with permanently connecte'd loads, energizes the auto-connected loads through the load sequence relays and operates for greater than or equal to 5 minutes while its generator is loaded with the emergency loads.

- lL Verifying that on the emergency core cooling system test signal, all diesel generator trips except engine overspeed, generator differential, low lube oil pressure, reverst power, loss of field and phase overcurrent with voltage restraint, are automatically bypassed.

5.

Verifying the diesel generator operates for greater than or equal to 60 minutes while loaded to greater than or equal to 3500 kw.

6.

Verifying that the auto-connected loads to each diesel generator do not exceed the 2000 hour0.0231 days 0.556 hours 0.00331 weeks 7.61e-4 months racing of 3850 kw.

7.

Verifying that the automatic load sequence relays are OPERABLE with each load sequence time within 10% of the required value.

BRUNSWICK - UNIT 1 3/48-4 Amendment No.

AdditionalInformationinSugport APPENDIX C:

of the BSEP Success Criteria 4

i 1

i i

C-1 i

Table C.1 RER SYSTEM AND SUPPORT SYSTEM SUCCESS CRITERIA RER - LPC Mode SUCCESS CRITERIA Flow Full Flow fro = two RHR pu=ps.

Heat Transfer Not Required.

Pu=p Seal Cooling Not Required.

RHR Roo= Cooling One Cooler.

RER - Shutdown Cooling Flow Full Flow fro: one RHR pu=p.

Heat Transfer One heat exchanger in operation.

Pu=p Seal Cooling Not Required.

RHR Roo: Cooling One Co*oler.

RHR - w'ith Fuel Pool Cooling Assist Flow Full Flow fro = one RHR pu=p.

Heat Transfer Both fuel pool heat exchangers in opearation.

Pu=p Seal Cooling Not Required.

RHR Roo= Cooling One Cooler.

RHR - Suppression Pool Cooling Flow

' Full Flow fro = one RHR pu=p.

Heat Transfer One heat exhanger in operation.

g Pu=p Seal Cooling Required.

RHR Roc = Cooling One Cooler.

RHR Service Water

Flow Full Flow fro = one pu=P to an active heat exchanger.

s

C-2

_Se:'vi c e *da t e =

/

Flev Full Flew tec= two pu=;3 ::

Cne CP DC n neacers, Lube Water Full T1cw C::a ont lube ua:a:

pu=p.

Fcr Decay Heat Re= eval Function Only.

4 e

o e

O

+-ee..

O e

e e

I

=

C-3 Table C.2 Case 1: Less of Orf-Site Power in Both Units BSE? Diesel Generster Failure Criter a Evalua:Len DO Failure Ceebinations Censecuences 1&2 e Loss of Unit 1 RER Loop A. & B. -

MOV's e Loss of Unit 1 Room Coolers A & 3 3&4 e Loss of Unit 2 RHR Loop A&B

/

MOV's e Loss cf Unit 2 Rect Coolers A & S 113 e Less of Unit 1 RHR Lcop A MOV's (Unit.1 RHR Loce 3 available with two RER Pu=ps) e Loss of Unit 1 Rec = Cooler A (Unit 1 Rocs Cooler B availables e Loss of Unit 2 Recs Cooler A

~

(Unit 2 Race Cooler B available)

a e -Loss of Unit 2 RHR Locp A MOV's (Unit 2 RHR Locp B available with tuo RHR pu=ps) 2&3 e Loss of Unit 1 RHR Lecp B MOV's (Unit 1 RER Loop A available with one RHR pu=p) e Loss of Unit 1 Roo: Cooler B (Unit 1 Roca Cooler A available) e Loss of Unit 2 Room Cooler A (Unit 2 Roc: Cccler B available) l e Loss of Unit 2 RER Loop A MOV's (Unit 2 RHR Lecp 3 available with one RHR pu=p) 1&4 e Loss of Unit 1 RHR Loop A MOV's (Unit 1 RHR Loop B available with one RER pu=p) e Loss of Unit 1 Rocs Cooler A (Unit 1 Rocs Cooler B available) e Loss of Unit 2 Rees coolec B (Unit 2 Rocs Cooler A available) e Loss of Unit 2 RER Loop B MOV's (Unit 2 RHR Lcep A available with one RHR pu=p) 2&4 e Loss of Unit 1 RHR Leop B MOV's (Unit 1 PHR Loop A available with two 3:1R pu=ps) e Loss of Unit 1 Rocs Cooler B s

C-4 (Unit 1 Recs Cccler A available) e Loss of Unit 2 Rees Cccler B ~

(Unit 2. Rocs Cocler A available).

e Loss' of Unit 2 RER Loop B MOV's (Unit 2 RER Lcop A available with two RHR pu=ps)

NCTIS:

This evaluation is based on a complete loss of off-site power to the plant and successful starting and leading of the diesel generators.

A revi aw of the decav heat removal systes study for BSIP (Reference 13) indicates that for a ec=clete loss of off-site cover event. eacn 2 sir Unit =ust nave at least one RHR loco witn one RER pu=p availaole for suttressica pool ecoling anc witn MCIC or nrc aval: nae. Ice neaccc:<

vesseA inventory maxeup.i==ediately after a reacter trip.

The availability oI cne crc 1 anc. nub syste=s will' cepes.c cn acequate DC power supplies during the loss of off-site power conditien. This can ce acec=plished by successful diesel starting and loadi:s-, or adecuate station battery capacity.

For this study it was assu:ed that adequate DC pcwer supplies were available for at least three hours af ter a loss of offsite power event. The DG failure ccebinations that liac te a less ef-decay heat removal capability in either Unit are given below:

1 and 2 or 3 and 4 9

l 5

i e

e

____._.._m__

- -,.. _,.,-,.. _,. ~,-

C-5 i

Table C.3 Case 2: Loss of Off-Site Power in Both Units Anc LOCA in One Unit ESIP Diesel Generator Failure Criteria Evaluation DG Failure Co=binatien(s)

Consecuences 1 &2 e Loss of Unit 2 RHR Loop A & B LPCI Nov.

o Loss or Unit 1 RHR Loop A & B Cooling MOV's.

e Loss of Unit 1 Roo"= Coolers A

& B.

o Loss of Unit 1 Core S; ray Loops A & B 3&4 e Loss of Unit 1 RHR Loop A & B LPCI MOV.

e Loss of Unit 2 RHR Loop A & B Cooling MOV's.

o' Loss of Unit 2 Roo= Coolers A

& B.

e Loss of Unit 2 Core Spray Loops A & B.

1&3 e Loss of Unit 1 RHR Loop A LPC:

MOV.

e Loss of Unit 1 RER Loop A Cooling MOV's (Unit 1 RHR Loop B available with two RHR pu=ps for cooling or LPCI.)

Loss of Unit 1 Core Spray Loop e

A (Unit 1 Core Spray Loop B available.)

e Loss of Unit 1 Roo= Cooler A (Unit 1

Roo=

Cooler B

available.)

i e Loss of Unit 2 Roo= Cooler A (Unit 1

Roos Cooler B

available.)

e Less of Unit 2 RHR Loop A LPC MOV.

e Loss of Unit 2 RHR Loop A cooling MOV's (Unit 2 RHR Loop B available with two RHR pumps for cooling LPCI.)

Loss of Unit 2 Core Spray Loop e

A (Unit 2 Core S; ray Loo; B available.)

i

+

6 i

~ _.. _

C-6 DG Tailure Co:bination(s)

Consequences 2&3 e Loss of Unit 1 RHR Loop A LPCI HOV (Unit 1

RHR Loop B

available with one pump for LP.CI.)

e Loss of Unit 1 RER Loop B Cooling MOV's (Unit 1 RHR Loop A available with one RHR pump i

for cooling.)

e Loss of Unit 1 Core Spray Locp B (Unit 1 Core Spray Loop A available.)

e Loss of Unit 1 Roo= Cooler B (Unit 1

Room Cooler A

available.)

e Less-of Unit 2 Roos Cooler A (Unit 2

Room ' Cooler B

available.)

e Loss of Unit 2 RHR Loop B LPCI MOV (Unit 2

RHR Loop A

available with one pu=p for i

LPCI.)

e Loss of Unit 2 RER Loop A

' cooling MOV's (Unit 2 RHR Loop B available with one RER--

pump.)

e Loss of Unit 2 Core Spray Loop

.A (Unit 2 Core Spray Loop B availabla.)

1&4 e Loss of Unit 1 RHR Loop B LPCI HOV (Unit

-1 RHR Loop A

available with one pucp for LPCI.)

e Loss of Unit 1 RHR Loop 'A MOV's (Unit 1 RER Loop B available with one RHR pu=p for cooling.)

e Loss of Unit 1 Core Spray Loop A (Unit 1 Core Spray Loop B available.)

e Loss of Unit 1 Room Cooler A (Unit 1

Roo=

Cooler B

available.)

e Less of Unit 2 Roos Cooler B (Unit' 2

Room Cooler A

available.)

e Loss of Unit 2 RHR Loop A LPCI MOV (Unit 2

RHR Loop B

available with one pump for l

LPCI.)

e Loss of Unit 2 RHR Loop B i

MOV's (Unit 2 RHR-Loop A available with one RHR pu=p for cooling.)

i

t s

C-7 EG Failure Cc=binatien(s)

Consecuences 1 & 4 (Cont.)

e Less of Unit 2 Core Spray Loep B (Unit 2 Core 3; ray Loop A available.)

2 & 4 e Loss of Unit 1 RHR Loop B LPCI.

e Loss of Unit 1 - RHR Loop B Cooling MOV's (Unit 1 RHR Loop A available with two RHR pu=ps for cooling or LPCI.)

e Loss of Unit 1 Core Spray Loop B (Unit 1 Core Spray Loop A available.)

e Loss of Unit 1 Roc = Cooler B available.).

~ Cooler A

(Unit 1

Roc =

e Less of Unit 2 Roc = Cooler B (Unit 2

Ree:

Cooler A

available.)

e Loss of Unit 2 RER Leop B LPC:

MOV.

e, Loss of Unit 2 RHR Loop B Cooling MOV's (Unit 2 RER Loop A available with two RER pu=ps for cooling or LPCI.)

e Loss of Unit 2 Core S; ray Lecp

'B (Unit 2 Core S; ray Loop A available.)

NOTES This evaluation is based on a ce=plete loss of offsite ;cwer to the plant and LOCA event in c:e Unit.

This is the FSAR oesign basis for the plant and requires two RER pu=ps and one core spray pu=p - for the Unit with the LOCA event, and one RER pu=p for safe shutdevn of the other Unit.

Based on this evaluation, diesel generater failure ce=binations that.did not =eet the above success criteria were designated as failures for the case.

These DG Failure Ce=binations are listed below.

1 and 2 3 and 4 1 and 4 2 and 3 l

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ML20205Q030

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