ML20235W127

Application for Amend to License NPF-3,revising Tech Specs to Allow one-time Extension of 18 Month Surveillance Interval for Insp & Operability Testing of Emergency Diesel Generators

ML20235W127
Person / Time
Site:	Davis Besse
Issue date:	10/09/1987
From:	Shelton D TOLEDO EDISON CO.
To:
Shared Package
ML20235W116	List: ML20235W112 ML20235W127 ML20235W129
References
TAC-66377, NUDOCS 8710160012
Download: ML20235W127 (22)

Text

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Docket No. 50-346 Y,1 cense No. NPF-3 Seriel No. 143G Enclosure-Pase 1

.'.FPLICATION FOR AMENDhTNT TO FACILITY OPERATING LICENSE NO. NPF-3 FOR DAVIS-BESSE NUCLEAR POWER STATION UNIT NO. 1 Attached are requested changes to the Davis-Besse Nuclear Power Station, Unit No. 1 Facility Operating License No. NPF-3. Also included are the Safety Evaluation and Significant Hazards Consideration.

The proposed change (submitted under cover letter Serial No. 1430) concern:

Section 3/4.8.1, Electrical Power Systems, A.C.' Sources, Specification 4.8.1.1.2d.1; Section 3/4.8.1, Electrical Power Systems, A.C. Sources, Specification ,

4.8.1.1.2d.3; and I Section 3/4.8.1, Electrical Power. Systems, A.C. Sources, Specification 4.8.1.1.2d.3(c).

k f By D. C. Shelton, Vice President, Nuclear Sworn and subscribed before me this 9th day of October, 1987, c4LLd._ (/

'otarfPublic,StateofOhio My commission expires f/

mo228!!!Bih8$ha P

DockhtNo.50-346 License No. NPF Serial No. 1430 Enclosure q Page 2  ;

The following information is provided to support issuance of the requested changes to the Davis-Besse Nuclear Power. Station, Unit No. 1 Operating License No. NPF-3, Appendix A, Technical Specifications 4.8.1.1.2d.1, 4.8.1.1.2d.3, and 4.8.1.1.2d.3(c).

A. Time Required to Implement: This change is to be implemented by'the licensee within 30 days following NRC issuance of the License Amendment, or by December 10, 1987, whichever occurs first.

B. Reason for Change (FCR No. 87-0129): Revise the Technical Specifications to allow a one-time extension in the 18 month surveillance -interval for inspection and operability testing of the Emergency Diesel Generators.

C. Safety Evaluation: See attached Safety Evaluation (Attachment No. 1).

D. Summary Significant Hazards Consideration: See attached Summary Significant Hazards Consideration (Attachment No. 2).

E. Significant Hazards Consideration: See attached Significant Hazards Consideration (Attachment No. 3) .

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O"" .' D:ckst No.'.50-346

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, SAFETY EVALUATION.

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INTRODUCTION (

The purpose oflthis safety evaluation is to review a proposed change, the

'one-time. extension.in'the 18 month surveillance' interval for inspection

'and operability testing of the Davis-Besse Emergency Diesel Generators 1

-(EDGs),-toethe Davis-Besse* Nuclear, Power Station (DBNPS). Unit No'. 1-

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-Operating' License, Appendix A, Technical Specifications,Jto ensure that'no n, unreviewed. safety questions. exist. This safety evaluation is being Lperformed-to meet'the requirements.of:100FR50.59. The DBNPS Technical

. Specifications, Section.3/4.8.1 Electrical Power Systems, A.C. Sources, Surveillance Requirements 4.8.l.1.2 and .4.8.1.2 require the EDGs .to be demonstrated . operable by performing certain tests once per 18 months.

Technical l Specification 4.0.2a provides for a maximum allowable extension

.of thisLinterval by 25 percent. For.any one 18 month interval this

.provides forLa maximum ~4.5 month extension. Technical Specification

'4'.0.2b requires.that the. total combined interval for any three consecutive tests is'not to exceed 3.25 times the~specified time interval. Therefore.

the total: combined interval for three consecutive tests cannot exceed 58.5 months..

TechnicalLSpecification 3.8.1.1.b requires that both.EDGs be operable in Modes 1 through 4. Technical Specification 3.8.1.2 requires that, as a minimum, one EDG be. operable in Modes 5 and 6. To demonstrate EDG

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operability, Surveillance ~ Requirements 4.8.1.1.2a (for Modes 5 and 6 -

requirements 4'.8.1.1'.2a.5'and 4.8.1.1.2a.7 need not be performed), b.  !

c, and d must be performed. 'All of these requirements have been currently I satisfiedLfor the EDGs. Based on the present schedule, all surveillance requirements are anticipated to be satisfied within the interval specified by the Technical Specification, including the 25 percent extension allowed {

by 4.0.2a..with the exception of two of the five' requirements of Surveil-

' lance Requirement 4.8.1.1.2d.

1 Surveillance Requirement 4.8.1.1.2d requires, at least once per 18 month =1, that certain inspection and operational tests be performed. The test interval of these requirements, including allowable extension, will

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_b'e. satisfied with the exception of the following two requirements: l Surveillance Requirement 4.8.1.1.2d.1, Subjecting the diesel to an I

. inspection in accordance with procedures prepared in conjunction

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with its manufacturer's recommendations for this class of standby j service. j l

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l Serial No. 1430 Attachment 1 Fage 2-Surveillance Requirement 4.8.1.1.2d.3(c), Simulating a loss of offsite power in conjunction with a safety injection actuation test i signal, and: ... Verifying that all diesel generator trips, except engine overspeed and generator differential, are automatically bypassed upon loss of voltage on the essential bus and/or an SEAS test signal.

l These two surveillance requirements were last performed on February 13, 1986 and January 20, 1986 for EDG 1-1 and 1-2, respectively. Thus, in order to meet the Technical Specification surveillance interval, including the 25 percent extension, and maintain the operable status of the EDGs, an inspection and trip test must be performed by January 3, 1988 for EDG 1-1 and December 10, 1987 for EDG 1-2. However, the scope of work required'to perform the vendor's recommended inspection includes over 45 separate maintenance tasks. This work is estimated to require a period of about two weeks.- This exceeds the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period allowed by the Action Statement of the Limiting Condition for Operation of this Technical Specification with one operable EDG while in Modes 1 through 4.

Therefore, a plant shutdown would be required prior to the fifth refueling outage, presently scheduled to commence February 1, 1988.

It is undesirable to perform the testing to demonstrate operability of the SFAS bypass of EDG trip functions during power operation. This testing is normally scheduled to be performed with either the EDG vendor's recommended inspection (4.8.1.1.2d.1) or integrated SFAS testing during a plant refueling outage. To perform this test during operation in Modes 1 through 4 would require completion of the test within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period allowed by the Action Statements of the Limiting Condition for Operation of the Technical Specification with one operablo EDG. It would also require that an EDG emergency run condition be simulated to test the bypassed trips. If this test is performed in Mode 5 or 6, the bypassed trips can be verified during an actual EDG emergency run condition, when the EDG is the sole source of power to the essential 4160V bus during the integrated SFAS test. Performing an EDG SEAS trip bypass test in conjunction with the integrated SFAS test provides a higher level of confidence of circuit operability.

This safety evaluation provides technical justification for a one-time  ;

extension of the 18 month surveillance schedule of the EDGs. This  !

extension would be applicable only to Surveillance Requirement 4.8.1.1.2d.1 and Surveillance Requirement 4.8.1.1.2d.3(c), as described above. Surveillance Requirement 4.8.1.2, which defines operability requirements for EDGs in Modes 5 and 6, also references these sections of 4.8.1.1.2. The inspection and testing of both EDCs is proposed to be completed prior to Cycle 6 operation and no later than March 31, 1988 for

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(Docket No. 50-346

- _ License.No.'NPF-3.1 1 Serial No. 1430 n( , . ' ' Attachment'l Page;3 *

EDG 1-1 and March 20, 1988 for.EDG 1-2. .This one-time surveillance

- interval extension would allow performance of the subject surveillance in a logical'and systematic m'anner during'the upcoming fifth refueling.

outage. TheLtotal: combined interval for the last three consecutive. tests

- would not exceed l3.25 times the specified interval. .If, due to an unscheduled. outage, the plant is required to be-shutdown in-Mode 5 or1 6

-for a period of time greater than two weeks. prior to the fifth refueling outage,-the required surveillance-testing is. identified ~1n the forced 1

outage plan'and is planned.to be performed during' that forced' outage.-

.In addition, this proposed Technical Specificat1on change corrects a typographical error'in Technical Specification 3/4.8.1, Surveillance

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. Requirements 4.8.1.1.2d.3, where "... safety injection actuation test signal'..." should. read "... safety features actuation system (SFAS) ~

test signalE..."..

g SYSTEMS AND COMPONENTS AFFECTED Emergency Diesel Generators (EDGs)

Safety Features Actuation System (SFAS)

DOCUMENTS AFFECTED t Davis-Besse Nuclear Power Station, Unit No. 1,. Operating License, Appendix A, Technical Specifications REFERENCES Davis-Besse Nuclear Power Station, Unit No. 1. Updated Safety Analysis Report,. July 1987 5

Davis-Besse Nuclear Power Station, Unit No. 1, Operating License.

Appendix A, Technien1 Specifications Morrison-Knudsen Company, Inc. letter to Toledo Edison Company dated September 29, 1987; subject: Evaluation for Extensiop of Maintenance, Emergency Diesel Generators United States Nuclear Regulatory Commission Generic Letter 84-15, dated July.2 1984; subject: Proposed Staff Actions to Improve and Maintain Diesel' Generator Reliability L _ _ ___ _

>Dockat No.iS0-346 License No. NPF-3 Serial No. 1430 Attachment 1  !

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FUNCTIONS OF SYSTEMS'AFFECTED The two redundant EDGs provide onsite standby power sources to supply their respective 4.16 kV essential busses upon loss of the normal and reserve power sources. The DBNPS EDGs are comprised of a General Motors (GM),

Electro-Motive Division, 20 cylinder, turbocharger, model S20645E4 engine coupled to an Electric Machinery Manufacturing Company 3250 KVA generator. The EDG is rated for a speed of 900 rpm, continuous electrical output.of 2600 kw and a continuous engine output'of 3600 BHP.

The EDG vendor is Morrison-Knudsen Company, Inc. Power Systems Division.

Each EDG will receive a starting signal when any of the following  ;

occurs

a. Loss of associated 4.16 kV essential bus voltage b.: Safety Features Actuation System Signal (SFAS)

c. Manual start '(local at the EDG engine control relay or:1dle start /stop panels or control room)

d. Test signals to simulate any of the above Each EDG is equipped with mechanical and electrical interlocks to ensure protection of personnel and to prevent or limit equipment. damage. A loss of essential bus voltage or a SFAS signal will cause a bypass of all EDG trips'except for engine overspeed and generator differential relay action.-

The engineered SFAS monitors plant variables to detect loss of Reactor Coolant System (RCS) boundary integrity and containment high radiation.

As dictated by plant conditions, SFAS initiates various engineered safety features. It also starts both EDGs on an SFAS level 2 actuation (low RCS pressure or high' containment pressure).

EFFECTS ON SAFETY The following discussion applies to Surveillance Requirement 4.8.1.1.2d and Surveillance Requirement 4.8.1.2 (which references Surveillance Requirement 4.8.1.1.2d). The effect of extending the EDG surveillance interval (including the 25 percent allowable extension) of 22.5 months by 3.5 months (to 26 months) is evaluated below for impact on the USAR analyzed events.

During the extension proposed for Surveillance Requirement 4.8.1.1.2d, all the surveillance requirements will remain in compliance with the 18 month interval, allowing for the 25 percent extension, except for ,

Surveillance Requirement 4.8.1.1.2d.1, EDG manufacturer's inspection, '

and Surveillance Requirement 4.8.1.1.2d.3(c), EDG trip and trip bypass t

testing. . The other surveillance requirements of section 4.8.1.1.2d are not required to be performed prior to June 1988 for either EDG, to satisfy the 18 month testing requirement. This testing includes the following:

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4.8.1.1.2d.2 .- generator load' rejection 4.8;1.1.2d.3(a) - essential bus load shedding 4.8.1.1.2d.3(b):- EDG ambient start and sequence loads 4.8.1.1.2d.5-

- auto' connected. loads do not exceed EDG 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating Further, the requirement to verify EDG operability for at least 60-minute's while loaded to:at least 2000 kW, Sirve111ance' Requirement 14~.8.1.1.2d.4 has been, and will' continue to be, performed monthly, -

although it.is only required to be performed by the Technical l Specifications once every 18 months. .All other requirements that are required to be performed monthly by Surveillance Requirement 4.8.1.1.2  ;

lshall continue to be performed. This monthly testint; will provide'a '

method of operability verification.and will indicate potential EDG problems. Similarly, in Modes 5'and 6 the surveillance requirements of.

Section 4.8.1.2 will be met, and operability of at least one EDG will be

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demonstrated by.the continued performance of this test during shutdown.

The last three consecutive EDG manufacturers'[. inspections performed in-ac'cordance with Surveillance Requirement 4.8.'1.1.2d.1 were completed

along with the EDG trip and trip bypass tests (Surveillance Requirement 4.8.1.1.2d.3(c)), on thes following: dates:

EDG 1 EDG 1-2

~ ' Augus t - 11, 1983 August 27, 1983 December 14, 1984 November 10, 1984 ,

February 13, 1986 January 20, 1986 i To comply with the Technical. Specification 4.0.2b requirement for the j total combined surveillance interval for three consecutive tests not to exceed 3.25 times the nominal 18 month interval, these inspections must l i

~be completed no later than: i I

EDG 1-1 EDG 1-2 i

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July 5, 1988 July 21, 1988 )

The proposed one-time EDG surveillance interval extension will require j that these surveillance requirements be performed no later than. I I

EDG 1-1 EDG 1-2 March 31, 1988 March 20, 1988

' Consequently, the__ requirement of Technical Specification 4.0.2b is adequately met, including the proposed one-time extension. Also, the  !

average duration of the last three consecutive surveillance intervals, l inclusive of.the proposed one-time extension, will be less than 555 days '

for EDC 1-1 and EDG 1-2,'which is not significantly longer than the nominal 18 month interval requirement of 550 days,

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- The EDG ' vendor lias' stated .that the inspection required by St.cVeillance

. Requirement 4.8.1.1.2d.11can be extended on a one-time basis, from 18 to

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26 months. This assessment is based on the EDG vendor's review and

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evaluation of the DBNPS.EDG's operating history and projected operation tuntil the proposed; inspection in Merch 1988 and the'EDG maintenance-

schedule. 'To support this extenofon the vendor also requested that specific EDG components be inspected.on both units. These items will ba-inspected in conjunction with scheduled EDG preventive maintenance tasks Land' completed. prior to the current Surveillance Requirement 4.8.1.1.2d.1  !

due- date' of Jar.uary 3,1988 for EDG 1-1 and December 10, 1987 for EDG 1-2.

These inspections were recommended by the EDG. vendor based on field

. service experience and provide additjonal assurance of'EDG operability. {

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.The vendor's assessment, clong with therextension of the inspection a ' interval for Surveillance Requirement 4.8.1.1.2d.3(c), is supported by the findingsiof the DBNPS'EDG surveillance program and the EDG trend analysis program. . Prior.to 1983, DENP5 EDGs Vere experiencing a higher

-than average failgre rate. The root causes of these failures (turbocharger.hnd air start. motor's) were identified and corrected. EDG availability in the last;100 starts, which dates back to 1983, has been. j very.'godd as'indicat'ed by.only two failures (reliability of 0.98/ demand) to start for EDG 1-1 and no f ailures (reliability of 1.00/ demand) to start l for' EDG .1-2  : Most recently, there have been no failures (reliability of 1.00/ demand) to start for either unit in the past 20 tests performed over j the previous 11 motiths. This individual EDG performance exceeds the NRC 1 performance standard proposed in Generic Letter 84-15 dated July 2, 1984, regarding Station Blackout. The combined performance of-both DBNPS EDGs

'(reliability of 0.99/ demand) surpasses the industry average for EDGs reliability of 0.98/ demand referenced in the same document. On September 6, 1987, a DBNPS plant trip challenged EDG 1-1, which started on loss of essential bus power and operated as required.

'More specifically, tho EDGE have not experienced significant operational  !

problems associated with the essential and non-essential trip functions. j The generator differential trip function has performed, without failure, as documented by the operating history of both EDGs. The EDG engine overspeed trip function hcs, likewise, demonstrated a high degree of 1

. reliability. The overspeed trip has not been bypassed when operating in  !

the emergency mode. The mechanism is an independent mechanical trip which cannot be affected by the presence or loss of an electrical signal. EDG 1-1 did experience a trip due to overspeed during surveillance testing on February 27, 1986. The identified root cause of the trip was the proximity of the hydraulic governor high speed stop (1015 rpm) to the overspeed trip setpoint (1020 rpm). The EDG vendor ,

evaluated the problem and recommended raising the overspeed trip range to i 1 1025 - 1040 rpm. Both EDG overspeed setpoints were reset to 1035 rpm, L retested and demonstrated operable. No additional problemt have occurred with the EDG engine overspeed trip function in subsequent testing.

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Non-essential EDG trips have also been demonstrated, without failure, to  !

be bypassed upon loss of voltage on the essential bus and/or an SFAS l signal as documented by the operating history of the EDGs. The EDG trip mechanism is not susceptible to degradation due to normal wear associated )

with EDG operation.

The DBNPS Lubrication Analysis and Monitoring Program trends EDG performance and includes monthly sampling and analysis of the EDG lube [

oil. The lube oil is examined for changes in oil viscosity and the prestnce of wear metals and contaminants indicative of EDG degradation.  !

EDG jacket cooling water and fuel oil are also examined monthly. Based on the results of EDG monthly surveillance testing performed on

. September 24, 1987, EDG 1-2 has jacket cooling water alkalinity slightly high out of specification. Although this condition does not presently ,

affect EDG operability, it is being closely monitored. Further testing is scheduled to evaluate this condition during the next EDG monthly surveil- ;

lance test. EDG 1-1 has shown no evidence of this condition. Presently, i there are no known problems that would prevent an extension to the 18 month EDG inspection surveillance interval. This program will continue to ,

receive close attention and any potential problems will be promptly {

investigated'and resolved. l The DBNPS trend analysis program recently included the collection of

. baseline EDG vibration data. This data, in conjunction with future vibration testing is expected to provide additional trend indication of EDG condition. The data analyzed to date indicates that the EDCs are in good operational condition and show no areas of vibrational concern, i Past available EDG lube oil viscosity data was also evaluated and the f results extrapolated to assess the effect of oil viscosity trends ou  !

future EDG operation. EDG 1-1 oil viscosity has decreased slightly, but  !

is still within the vendor's recommended tolerance, since the last oil changa. EDG 1-2 oil viscosity has increased slightly, within the vendor's recommended tolerance, since the last oil change. However, analysic indicates that the viscosity limits for either EDG, as  !

recomm. ended by the vendor, will not be exceeded by the estimated EDG '

operation ducing the requested surveillance interval extension. If, in

.the course of monthly EDG lube oil inspection, the viscosity of the oil approaches a bounding value, additional actions will be taken including increased monitoring of the EDG and, if necessary, oil replacement.

The. previous EDG 18 month inspection of EDG 1-1 and EDG 1-2 showed no indication of unusual wcat of the ccaponents recommended for examination by the vendor. Since the EDGs are only used for standby service and operate very few hours between overhauls, engine wear is understandably minimal.

Dockst No.'50-346 License No. NPF-3 Serial No. 1430 Attachment 1 Page 8 Based on the EDG vendor's recommendation, past and continuing EDG surveillance and analysis program and previous operating reliability, the one-time extension of 3.5 months would not increase the probability of degradation of the EDGs.

The correction of'the typographical error in Technical Specification 3/4.8.1, Surveillance Requirement 4.8.1.1.2d.3 of "... safety system  !

(SFAS) test signal . . ." da an administrative change which has no effect ou EDG testing, operation, or safety.

UNREVIEWED SAFETY QUESTION EVALUATION Revis1ng the Technical Specification surveillance interval for the EDGs as proposed'above will not increase the probability of occurrence of any accident previously evaluated in the USAR because the EDGs are standby equipment which do not contribute to the occurrence of any USAR accident. Extension of the EDG surveillance interval does not change the EDG's function or operation (10CFR50.59(a)(2)(i)).

Revising the Technical Specification surveillance interval for the EDGs  ;

as proposed above will not increase the probability of occurrence of a l malfunction of equipment important to safety because the performance of the EDGs has not been compromised. The surveillance interval extension for EDG inspection is acceptable based on the operating and maintenance ,

history and projected operation and inspections of the EDGs. Past l performance of the EDGs has indicated a high degree of reliability, l especially the more recent operating history. The EDGs will continue to be tested monthly as required by Technical Specifications (10CFR50. 59 (a) (2) (1)) .

Revising the Technical Specification surveillance interval for the EDGs as propused above will not increase the consequences of a malfunction of equipment important to safety previously evaluated in the USAR because no change to EDG operation will result (10CFR50. 59 (a) (2) (1)) .

Revising the Technical Specification surveillance interval for the EDCs an proposed above will not create the possibility for e.n accident of a different type than any evaluated previously in the USAR since proper operability of the EDGs is still assured and all failure modes are the same as previously analyzed (10CFR50.59(a)(2)(11)).

Revising the Technical Specification surveillance interval for the EDGs as proposed above will not create the possibility of a malfunction of a different type than any evaluated previously in the USAR because there 10 no change to the operational limits or physical design of the E90s (10CFR50. 59 (a) (2) (ii)) .

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Dockat No. 50-346 License No. NPF-3 Serial No. 1430 Attachment 1 Page 9 Revising the Technical Specification surveillance interval for the EDGs as proposed above will not reduce the margin of safety as defined in the basis for any Technical Specification because all the assumptions in the USAR analyses are unchanged and the consequences of a malfunction of the EDGs are within the bounds previously. analyzed (10CFR50.59(a)(2)(111)).

The correction of the typographical error in Technical Specification 3/4.8.1, Surveillance Requirement 4.8.1.1.2d,3 is an administrative change only and, accordingly, does not constitute an unreviewed safety question.

CONCLUSION i Based on the above, it is concluded that the proposed Technical Specification changes do not constitute an unreviewed safety question.

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License No. NPF-3 Seriel No. 1430 Attachment 2 Page 1

SUMMARY

SIGNIFICANT HAZARDS CONSIDERATION Description of Amendment Request: This amendment request proposes a one-time extension of 3.5 months to the Emergency Diesel Generator (EDG) 18-month surveillance interval for inspection of the EDG and verification of diesel generator trip bypasses upcn receipt of a Safety Features Actuation System (SFAS) signal. These requirements are contained in Technical Specifications (TS) 4.8.1.1.2d.1 and 4.8.1.1.2d.3(c),

respectively, and are. referenced in TS 4.8.1.2 for Modes 5 and 6 operation.

In addition, the amendment request proposes to correct a typographical error in TS 4.8.1.1.2d.3.

Basis for Proposed No Significant Hazards Consideration Determination:  ;

The purpose of the change is to avoid an early shutdown of the Davis-Besse Nuclear Power Station prior to the schedulad February 1, 1988 refueling outage to corduct the inspection and testing. The present schedule, including the allowable extension permitted by TS, would require the EDGs to be tested as early as December 10, 1987, and would require a' two week outage for each EDG (total of four weeks) . The extension would allow entry into the scheduled refueling outage without requiring a prior unscheduled outage.

The EDGs have consistently been tested in the pact and, based on the last 100 etarts, have demonstrated a combined performance of 0.99/ demand (which sarpasses the industry average of 0.98/derand). In addition, the plant trip of September 6, 1987 challenged one of the EDGs and it performed as required.

The EDG vendor has provided concurrence with the extension of the interval for performing the required inspections, thereby operation of the EDCs is not compromised from this perspective. The EDG trend program provides information relative to EDG performance for ongoing evaluation.

The proposed extension is within the requirement of TS 4.0.2b, which requires that the last three consecutive tests tsve a combined interval of not more than 3.25 times the nominal 18 month interval. Also, the average duration for the last three test intervals, including the proposed extension, is less than 555 days which compares favorably with the TS required nominal 18 month interval duratica of 550 days.

The safety significance of the extension is in consideration of extending the 18 month tests (including TS allowed extensions) by 3.5 months and the confidence that the EDGs will perform their function with the extension of time. However, based on the above considerations justifying the extension and that an unscheduled outage prior to the scheduled refueling outage is not warranted, it is concluded that:

Dockat'No. 50-346 License No. NPF-3 Serial No. 1430

- Attachment-2 Page 2 The extension will not result in a significant increase in the probability or consequences of a previously evaluated accident nor vill it create the possibility of a new or different kind of an accident. A sis;nificant reduction in the margin of safety is not involved. Theiafore, the proposed amendment is determined not to involve a significant hazards consideration.

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SIGNIFICANT HAZARDS CONSIDERATION ~

INTRODUCTION The purpose of this Significant Hazards. Consideration is ' to' review a l <

proposed change,- thefone-time extension in the 18 month surveillance

.jnterval for inspection and operability testing'of the Davis-Besse Emergency Diesel Generators (EDGs), to the Davis-Besse Nuclear Power Station (DBNPS)

- Unit No. 1 Operating. License, Appendix A', Technical Specifications, to ensure that no significant hazard considerations exist. This significant hazar' ds consideration is being performed. to meet the requirements of

~10CFR50.92(c).. The DBNPS Technical Specifications, Section 3/4.8.1 Electrical Power Systems, A.C. Sources, Surveillance Requirements 4.8.1.1.2 and 4.8.1.2l require the EDGs to be demonstrated operable by performing.

certain inspections and tests once per 18 months. Technical Specification

'4.0.2a provides for a maximum allowable extension of this interval by 25 percent. For any one 18 month interval this provides for a maximum 4.5 month extension. Technical Specification 4.0.2b requires that the total.

combined interval for.any.three consecutive tests is not to exceed 3.25 times the.specified time interval. Therefore, the total combined interval.

for three consecutive tests cannot exceed 58.5 months.

Technical Specification 3.8.1.1.b requires that both EDGs be operable in Modes 1.through 4. Technical Specification 3.8.1.2 requires that, as a

- minimum, one EDG be operable in Modes 5 and 6. To demonstrate EDG operability, Surveillance Requirements 4.8.1.1.2a (for Modes 5 and 6, requirements 4.8.1.1.2a.5 and 4.8.1.1.2a.7 need not be performed), b, c, and d must be performed. All of these requirements have been currently. satisfied for the EDGs.. Based on the present schedule, all surveillance requirements are. anticipated to be satisfied within the interval specified by the Technical Specification, including the 25 percent extension allowed by 4.0.2a, with the exception of two of the five requirements of Surveillance Requirement 4.8.1.1.2d.

Surveillance Requirement 4.8.1.1.2d requires, at least once per 18 months, that certain inapection and operational tests be performed. The test interval of these requirements, including allowable extension, will be satisfied with the exception of the following two requirements:

Surveillance Requirement 4.8.1.1.2d.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.

i Dockst No. 50-346 License No. NPF-3 Serial No. 1430 Attachment 3 Page 2 l

Surveillance Requirement 4.8.1.1.2d.3(c), Simulating a loss of offsite power in conjunction with a safety injection actuation test signal, and: ... Verifying that all diesel generator trips, except engine overspeed and generator differential, are automatically bypassed upon loss of voltage on the essential bus and/or an SFAS test. signal.

These two surveillance requirements were last performed on February 13, 1986 and January 20, 1986 for EDG 1-1 and 1-2, respectively. Thus, in order to meet the Technical Specification surveillance interval, including the 25 percent extension, and maintain the operable status of the EDGs, an inspection and trip test must be performed by January 3, 1988 for EDG 1-1 and December 10, 1987 for EDG 1-2. However, the scope i of work required to perform the vendor's recommended inspection includes l over 45 separate maintenance tasks. This work is estimated to require a period.of about two weeks. This exceeds the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period allowed by the Action Statement of the Limiting Condition for Operation of this Technical Specification with one operable EDG while in Modes 1 through 4.

Therefore, a plant shutdown would be required prior to the fifth refueling outage, presently scheduled to commence February 1, 1988.

It is undesirable to perform the testing to demonstrate operability of the SFAS bypass of EDG trip functions during power operation. This testing is normally scheduled to be performed with either the EDG vendor's recommended inspection (4.8.1.1.2d.1) or integrated SFAS testing during a plant refueling outage. To perform this test during operation in Modes 1 through 4 would require completion of the test within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> period allowed by the Action Statements of the Limiting Condition for Operation of the Technical Specification with one i operable EDC. It would also require that an EDG emergency run condition  !

be simulated to test the bypassed trips. If this test is performed in l Mode 5 or 6, the bypassed trips can be verified during an actual EDG 1 emergency run condition, when the EDG is the sole source of power to the )

essential 4160V bus during the integrated SFAS test. Perfoming an EDG '

SFAS trip bypass test in conjunction with the integrated SFAS test provides  ;

a higher level of confidence of circuit operability.

This significant hazards consideration provides technical justification for a one-time extension of the 18 month surveillance schedule of the  !

EDGs. This extension would be applicable only to Surveillance Requirement 4.8.1.1.2d.1 and Surveillance Requirement 4.8.1.1.2d.3(c), as described above. Surveillance Requirement 4.8.1.2, which defines operability requirements for EDGs in Modes 5 and 6, also references these sections of j 4.8.1.1.2. The inspection and testing of both EDGs is proposed to be completed prior to Cycle 6 operation and no later than March 31, 1988 for f

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' License No. NPF-3 Serial.No. 1430 Attachment 3

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EDG 1-l'and March 20, 1988 for EDG 1-2. This one-time surveillance interval extension would allow performance of the subject surveillance in a logical and systematic manner during the upcoming fifth refueling outage. The total combined interval for the last three consecutive tests would not exceed 3.25 times the specified interval. If, due to'an unscheduled outage, the plant is required to be shutdown in Mode 5 or 6 for a period of time greater than two weeks, prior to the fifth refueling outage, the required inspection and surveillance testing is identified in j the forced outage plan and is planned to be performed during that forced 4 outage.

In addition, this proposed Technical Specification change corrects a typographical error in Technical Specification 3/4.8.1, Surveillance Requirement 4.8.1.1.2d.3, where "... safety injection actuation test signal ..." should read "... safety features actuation system (SFAS) test signal ...".

i SYSTEMS AND COMPONENTS AFFECTED Emergency Diesel Generators (EDGs)

Safety Features Actuation System (SFAS)

DOCUMENTS AFFECTED Davis-Besse Nuclear Power Station, Unit No. 1, Operating License, Appendix A, Technical Specifications REFERENCES Davis-Besse Nuclear Power Station, Unit No. 1, Updated Safety Analysis Report, July 1987 Davis-Besse Nuclear Power Station, Unit No. 1, Operating License.

Appendix A, Technical Specifications 1 i

Morr.ison-Knudsen Company, Inc. letter to Toledo Edison Company dated j September 29, 1987;

Subject:

Evaluation for Extension of Maintenance,  !

Emergeney Diesel Generators l

United States Nuclear Regulatory Commission Generic Letter 84-15, dated July 2, 1984;

Subject:

Proposed Staff Actions to Improve and Maintain Diesel Generator Reliability i

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Docket No. 50-346 l License No..NPF-3 Serial No. 1430  ;

Attachment 3 Page 4' FUNCTIONS OF SYSTEMS AFFECTED The two redundant EDGs provide onsite standby power sources to supply their l respective 4.16 kV essential busses upon loss of the normal and reserve power sources. The DBNPS EDGs are comprised of a General Motors (GM),

Electro-Motive Division, 20. cylinder, turbocharger, model S20645E4 engine coupled to an Electric Machinery Manufacturing Company 3250 KVA generator. The EDG is rated for a speed of 900 rpm, continuous electrical output of 2600 kw and a continuous engine output of 3600 BHP.

The EDG vendor is Morrison-Knudsen Company, Inc. Power Systems Division.

Each EDG will receive a starting signal when any of the following occurs:

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a. Loss of associated 4.16 kV essential bus voltage

b. Safety Features Actuation System (SFAS) signal

c. Manual start (local at the EDG engine control relay or idle start /stop panels or control room)

d. Test signals to simulate any of the above Each EDG is equipped with mechanical and electrical interlocks to ensure protection of personnel and to prevent or limit equipment damage. A loss of essential bus voltage or a SFAS signal will cause a by.nass of all EDG trips except for engine overspeed and generator differential relay action.

The engineered SFAS monitors plant variables to detect loss of Reactor Coolant System (RCS) boundary integrity and containment high radiation. 3 As dictated by plant conditions, SFAS initiates various engineered safety  !

features. It also starts both EDGs on an SFAS level 2 actuation (low RCS pressure or high containment pressure).

EFFECTS ON SAFETY The following discussion applies to Surveillance Requirement 4.8.1.1.2d and Surveillance Requirement 4.8.1.2 (which references Surveillance i Requirement 4.8.1.1.2d). The effect of extending the EDG surveillance interval (including the 25 percent allowable extension) of 22.5 months by 3.5 months (to 26 months) is evaluated below for impact on the USAR analyzed events.

During the extension proposed for Surveillance Requirement 4.8.1.1.2d,  ;

all the surveillance requirements will remain in compliance with the 18 month interval, allowing for the 25 percent extension, except for Surveillance Requirement 4.8.1.1.2d.1, EDG manufacturer's inspection, and Surveillance Requirement 4.8.1.1.2d.3(c), EDG trip and trip bypass j testing. The other surveillance requirements of section 4.8.1.1.2d are j not required to be performed prior to June 1988 for either EDG, to l satisfy the 18 month testing requirement. This testing includes the l following:

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, Dockst No'.s50-346 License No. NPF-3 Serial No. 1430 LAttachment 3 Page'5.

' 4. 8.1'.1. 2d . 2 - generator load rejection:

4.8.1.1.2d.3(a) - essential bus load shedding .

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.4.8.1.1;2d.3(b).- EDG' ambient start and' sequence loads

'4.8.1.1.2d.5, - auto: connected loads'do not exceed EDG 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating.

.Further, the. requirement to verify EDG operability.for at least 60 J

-minutes while-loaded to at least'2000 kW, Surveillance Requirement

.4.8.1.1.2d.4 has been, and will continue to be, performed monthly,

• although it is only required to be performed by the Technical Specifiestions'once every 18. months. All other requirements that are required to be performed monthly by Surveillance Requirement'4.8.1.1.2 shall continue to be performed. This monthly testing will provide a

-method of operability verification and will indicate potential EDG problems. ;Similarly, in Modes l5 and 6 the surveillance requirements of section 4.8.1.2'will be met, and operability of at least one EDG will be demonstrated by the continued performance'of this test during shutdown.

-The last three consecutive EDG manufacturers' inspection's performed in accordance with Surveillance Requirement 4.8.1.1.2d.1 were-completed along with the EDG trip and trip bypass tests (Surveillance Requirement 4.8.1.1.2d.3(c)), on the following dates:

EDG 1-1 EDG 1-2 August 11, 1983 August 27, 1983 December 14, 1984 November 10, 1984 February 13. 1986 January 20, 1986 To. comply with.the Technical Specification 4.0.2b requirement fer the total combined surveillance interval for three consecutive tests not to exceed 3.25 times the nominal 18 month interval,'these inspections must

-be completed no later than:

EDG 1-1 EDG 1-2 July 5, 1988 July 21, 1988 l The proposed one-time EDG surveillance interval extension will require that these surveillance requirements be performed no later than:  !

i EDG 1-1 EDG 1-2 )

March-31, 1988 March 20, 1988 l'

{ Consequently, the requirement of Technical Specification 4.0.2b is adeauntely met, . including the proposed one-time extension. Also, the average duration of the last three consecutive surveillance intervals.

inclusive of the proposed one-time extension, will be less than 555 days for EDG 1-1 and EDG 1-2, which is not significantly longer than the nominal 18 month interval requirement of 550 days.

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~Dockat No'. 50-346 License No. NPF-3

. Serial No. 1430' Attachment 3 Page'6-The EDG, vendor has stated that the inspection required by, Surveillance Requirement 4.8.1'.1.2d.1 can be extended on a one-time basis,'from 18 to 26 months. This assessment is based on the EDG vendor's review and

. evaluation of the'DBNPS SDG's operatingLhistory and projected operation until the proposed inspection in March 1988 and'the EDG maintenance schedule. To support this extension the vendor also requested that specific EDG components be inspected on both units'.. These items will be inspected in conjunction with scheduled EDG preventive maintenance tasks and completed. prior to the current Surveillance Requirement 4.8.1.1.2d,1 due date of January 3, 1988 for EDG 1-1 and December 10, 1987 for EDG 1-2.

These inspections were recommended.by the EDG vendor based on field service experience and provide additional assurance of EDG operability.

The vendor's assessment, along with the extension of the inspection  !

interval for Surveillance Requirement 4.8.1.1.2d.3(c), is supported by a the findings of the DBNPS EDG surveillance program and the EDG' trend l analysis program. Prior to 1983, DBNPS EDGs were experiencing a higher than. average failure rate. The root causes of these failures <

(turbocharger and air start motors) were identified and corrected. EDG availability in the last 100 starts, which dates back to 1983, has been very good as indicated by only two failures (reliability of 0.98/ demand) to start for EDG 1-1 and no failures (reliability of 1.00/ demand) to start for EDG 1-2. Most recently, there have been no failures (reliability of 1.00/ demand) to start for either unit in the past 20 tests performed over the previous 11 months. This individual EDG performance exceeds the NRC performance standard proposed in Generic Letter 84-15 dated July 2, 1984, regarding. Station Blackout. The combined performance of both DBNPS EDGs (reliability of 0.99/ demand) surpasses the industry average for EDGs reliability of 0.98/ demand referenced in the same document. On September 6, 1987, a DBNPS plant trip challenged EDG 1-1, which started on loss of essential' bus power and operated as required.

More specifically, the EDGs have not experienced significant operational  ;

problems associated with the essential and non-essential trip functions.

'the generator differential trip function has performed, without failure, as. documented by the operating history of both EDGs. The EDG engine' overspeed trip function has, likewise, demonstrated a high degree of reliability. The overspeed trip has not been bypassed when operating in the emergency mode'. The mechanism is an independent mechanical trip which cannot be affected by the presence or loss of an electrical signal. EDG 1-1 did experience a trip due to overspeed during surveillance testing on February 27, 1986. The identified root cause of the trip was.the proximity of the hydraulic governor high speed stop (1015 rpm) to the overspeed trip setpoint (1020 rpm). The EDG vendor evaluated the problem and recommended raising the overspeed trip range to 1025 - 1040 rpm. Both EDG overspeed setpoints were reset to 1035 rpm, retested and demonstrated operable. No additional problems have occurred with the EDG engine overspeed trip function in subsequent testing.

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'Non-essential EDG trips have also been demonstrated, without failure, to be bypassed upon loss of voltage on the essential bus and/or an SFAS signal as documented by the operating history of the EDGs. The EDG trip mechanism is not susceptible to degradation due to normal wear associated ,

with EDG operation. '

The DBNPS Lubrication Analysis and Monitoring Program trends EDG <

performance and includes monthly sampling and analysis of the EDG lube l oil. The lube oil is examined for changes in oil viscosity and the presence of wear metals and contaminants indicative of EDG degradation.

Past available EDG lube oil viscosity data has been evaluated and the ,

results extrapolated to assess the effect of oil viscosity trends on i future FDG operation. EDG 1-1 oil viscosity has decreased slightly, but la still within the vendor's recommended tolerance, since the last oil change. EDG 1-2 oil. viscosity has increased slightly, within the vendor's recommended tolerance, since the last oil change. However, analysis indicates that the viscosity limits for either EDG, as recommended by the  !

vendor, will not be exceeded by the estimated EDG operation during the requested surveillance interval extension. If, in the course of monthly EDG lube oil inspection, the viscosity of the oil approaches a bounding value, additional actions will be taken including increased monitoring of the EDG and, if necessary, oil replacement.

i EDG jacket cooling water and fuel oil are also examined monthly. Based j on the results of EDG monthly surveillance testing performed on September 24, 1987, EDG 1-2 has jacket cooling water alkalinity slightly high out of specification. Although this condition does not presently affect EDG operability, it is being closely monitored. Further testing is scheduled to evaluate this condition during the next EDG monthly surveillance test.

EDG l-1 has shonn no evidence of this condition. Presently, there are no known problems that would prevent an extension to the 18 month EDG inspection surveillance interval. This program will continue to receive close attention and any potential problems will be promptly investigated and resolved.

The DLNPS trend analysis program recently included the collection of baseline EDG vfbration data. This data, in conjunction with future vibration testiag is expected to provide additional trend indication of EDG condition. The data analyzed to date indicates that the EDGs are in good operational condition and show no areas of vibrational concern.  ;

The previous EDG 18 month inspection of EDG 1-1 and EDG 1-2 showed no indication of unusual wear of the components recommended for examination by the vendor. Since the EDGs are only used for standby service and operate very few hours between overhauls, engine wear is understandably minimal.

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Based on the EDG vendor's recommendation, past and continuing EDG surveillance and analysis program and previous operating reliability, the one-time extension of 3.5 months would not increase the probability of degradation of the EDGs.

The correction of the' typographical error in Technical Specification 3/4.8.1, Surveillance Requirement 4.8.1.1.2d.3 of "... safety system (SFAS) test signal .." is an administrative change which has no effect on EDG testing, cperation, or safety.

SIGNIFICANT HAZARDS CONSIDERATION The proposed changes do not involve a significant hazards consideration because the operation of the Davis-Besse Nuclear Power Station, Unit No. 1 in accordance with this change would:

1. Not involve a significant increase in the probability or consequences of an accident previously evaluated (10CFR50.92 (c) (1)) .

The probability or consequences of an accident previously evaluated is not increased because the EDGo are standby equipment which do not contribute to the occurrence of any accident. The ability of the EDCs to respond and operate as required will not be degraded. Past performance of the EDGs has indicated a high degree of reliability, especially the more recent operating history. The EDGs will continue to be tested monthly as required by Technical Specifications.

2. Not create the possibility of a new or different kind of accident from any accident previously evaluated (10CFR50.92(c)(2)).

The proposed Technical Specification change will not create the possibility of a new or different kind of accident from any previously evaluated because proper operability of the EDGs is still assured'and all failure modes are the same as previously analyzed. There.is no change to the operational limits or physical design of the EDGs.

3. Not involve a significant reduction in the margin of safety (10CFR50.92 (c) (3)) .

The proposed Technical Specification change does not involve a significant reduction in the margin of safety because all the assumptions in the USAR analyses are unchanged and the consequences of a malfunction of the EDGs is within the bounds previously analyzed.

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.t j it The correction of the typographical error in Technical Specification

'3/4.8.1', Surveillance Requirement 4.8.1.1.2d.3, is an administrative change only and, accordingly, does not involve a significant hazards consideration.

CONCLUSION J l

Therefore, it is concluded that the proposed Technical Specification changes do not involve a significant hazards consideration.'

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