FVY-84-126, Forwards Response to Generic Ltr 84-15, Diesel Generator Reliability. Existing Diesel Generator Surveillance Program Minimizes Number of Fast Cold Starts

Forwards Response to Generic Ltr 84-15, Diesel Generator Reliability. Existing Diesel Generator Surveillance Program Minimizes Number of Fast Cold Starts

ML20107B016
Person / Time
Site:	Vermont Yankee
Issue date:	10/29/1984
From:	Murphy W VERMONT YANKEE NUCLEAR POWER CORP.
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
FVY-84-126, GL-84-15, NUDOCS 8411020052
Download: ML20107B016 (11)

Text

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w. .a VERMONT YANKEE NUCLEAR POWER CORPORATION FVY 84-126

. RD 5, Box 169, Ferry Road, Brattleboro, VT 05301 ,,,,y 7g y ENGINEERING OFFICE 1671 WORCESTER ROAD

• FRAMINGHAM, MASSACHUSETTS 01701 October 29, 1984 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Darrell G. Eisenhut, Director Division of Licensing

References:

a) License No. DPR-28 (Docket No. 50-271) b) Letter, USNRC to VYNPC, dated 7/16/84 (Generic Letter 84-15)

Subject:

Response to Generic Letter 84-15, Diesel Generator Reliability We have completed our review of Reference b) and are forwarding our response to your concerns. Enclosures 1, 2 and 3 respond to the corresponding enclosure of Reference b).

We trust this information is satisfactory; however, if you have any questions, clease contact us.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION W AYfx b Warren . Murphy '

Vice P esident d Manager of Operations WPM /dm i

gh 8411020052 841029 I 8l PDR ADOCK 05000271 P PDR l

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ENCLOSURE 1 Reduction in Number of Cold Fast Surveillance Tests for Diesel Generators Vermont Yankee's existing program for Diesel Generator Surveillance minimi-zes the number of cold fast starts.

Monthly testing as well as testing necessary to demonstrate operability as required by Technical Specifications (when other systems are declared inoperable) are preceded by a 2 to 3 minute pre-lubrication. In addition, as a measure to further reduce cold start wear, procedures require that electrical loading be limited to 500 kw until all low temperature alarms have been cleared.

The only. exception to these requirements is the "ECCS integrated test". This test is performed once per operating cycle and must duplicate the actual con-d.tions'under wh'ch the diesel' generators are required to automatically start; as such, no pre-lubrication is performed. Based on a cold start frequency of once.per operating cycle, we do not feel that an excessive number of cold starts

, are performed. We do, however, support the premise (stated in Reference b) that-diesel generator. reliability can be increased by reduced operability testing and

-are therefore pursuing-efforts to eliminate the requirement for diesel generator operability testing when an emergency core cooling system or a related subsystem is declared inoperable.

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ENCLOSURE 2_

Diesel Generator Reliability Data The current reliability of diesel generators at Vermont Yankee is as follows:

_LAST 100 DEMANDS LAST 20 DEMANDS

- Diesel Generator A 97% 100%

Diesel Generator B 99% 100%

A time histcry tabulation of demands and failures is listed in Appendix A.

In regard to Regulatory Guideline 1.108 C.3.A, plant records provide a history of Diesel Generator Surveillance testing. Valid starts and failures are determined using Section C.2.e of Regulatory Guide 1.108 as guidance. Historical information such as maintenance, repair and operating data, as well as failure causes, although not maintained in a single log, is readily available from Maintenance and Operations records. Statistical analysis is performed based on failures, with adverse trends identified for plant management examination.

Reliability factors based on the number of failures over the past 100 demands (as suggested by the regulatory guide)' are not routinely calculated.

Although this information is easily obtained, qualitative evaluation of perfor-mance history is preferred. - Records of specific failures as well as those of general maintenance are periodically reviewed in an effort to identify:

1. weaknesres in subcomponents;

2. design problems which may become apparent due to age;

3 accelerated wear due-to environment or other factors (vibration, heat, etc.); and 4 maintenance or operation failures.

The results of this evaluation are utilized to detect adverse trends and determine corrective action.

F ENCLOSURE 3 Diesel Generator Reliability The example Technical Specification presented in Enclosure 3 to Reference b) provides an effective means of surveillance testing which accelerates as reliability degrades. Controls of this nature appear particularly relevant to

. plants whose Technical Specifications are grounded in Probabilistic Risk Assessment. Plants such as Vermont Yankee whose . Technical Specifications are not, however, may find it inappropriate to assimilate the divergent methodology.

At Vermont Yankee, emphasis is on increased Maintenance or design change when diesel performance begins to degrade.- This serves to. identify and correct component deficiencies before failure. In the event a failure does occur, the specific cause is identified and a corrective action proposed.

Examples of modifications resulting from degraded diesel performance are:

Plant Design Change Request (PDCR) 74-5 which replaced synthetic hoses between injection pumps with more reliable steel tubing; PDCR 84-03, which replaced faulty stopping relays with an _ improved model; and a revision to Procedure 0P 5223 which increases the routine maintenance of starting air check valves.

Increased maintenance upon degradation of performance (rather than increased surveillance) in _ concert with _a thorough and well organized main-tenance program has yielded consistently high diesel generator reliability fac-tors.

Based on our present program for diesel generator maintenance, and our history of high diesel generator reliability, we believe that the objectives outlined in References b) and c) are met.

g 1 APPEtOIX A j I

HISTORICAL

SUMMARY

-OF EMERGENCY DIESEL GENERATOR DEMANDS 1984 EMERGENCY DIESEL GENERATOR A EMERGENCY DIESEL GENERATOR B Date Reason for Demand Result Date Reason for Oemand Result 1-10-84 Routine Monthly Acceptable 1-11-84 Routine Monthly Acceptable 2-6-84 Routine Monthly Acceptable 2-7-84 Routine Monthly Acceptable 3-5-84 Routine Monthly Acceptable 3-5-84 Routine Monthly Acceptable 4-9-84 Routine Monthly Acceptable 4-9-84 Routine Monthly- Acceptable 4-12-84 Special--retest of dry Acceptable 5-4-84 Special--prior to Acceptable tank makeup valve removal of LPS 5-4-84 Special--prior to Acceptable 5-8-84 Routine Monthly Acceptable removal of LPS 5-8-84 Routine Monthly Acceptable- 5-21-84 Special--A D/fG removed Acceptable from service for maintenance L :5-21-84 Special--Retest after Acceptable 6-5-84 Routine Monthly Acceptable ,

. work '

l. 6-4-84 Routine Monthly Acceptable 7-14-84 Special--after maint. Acceptable 7-6-84 Special--after maint. Acceptable 7-28 Special--after maint. Acceptable

7-7-84 -Special--after maint. Acceptable 8-9-84 Routine Monthly Acceptable Special--EDCR 80-49

~ 7-26-84 Acceptable 8-9-84 Special Acceptable 7-27-84 Special-operability Acceptable 9-4-84 Routine Monthly Acceptable after overspeed test

, 7-31-84 Special--operational test of alternate shutdown method Acceptable i

=7-31-84 Special--alt. shutdown Acceptable L

testina L 8-84 Routine' Monthly Acceptable 9-4-84 Routine Monthly Acceptable i.

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APPENDIX A HISTORICAL

SUMMARY

-OF EMERGENCY DIESEL GENERATOR DEMANDS 1983 EMERGENCY DIESEL GENERATOR A EMERGENCY DIESEL GEERATOR B Date Reason for Demand Result Date Reason for Demand Result 1-12-83 Routine Mnthly Surv Acceptable 1-8-83 Special--breaker reolacement Acceptable 1-14-83 Special .

(1) 1-12-83 Routine Mnthly Surv Acceptable Failed 1-14-83 Special--functional 1-14-83 Special--D/G A inop Acceptable test following maint. Acceptable 2-7-83 Routine monthly- Acceptable 2-8-83 Routine Monthly Acceptable 3-1-83 Special--A RHR Hx out 3-1-83 Special--A RHR Hx out of service Acceptable of service Acceptable 3-2-83 Special--A RHR sub- 3-2-83 Special--A RHR subsys-system out of service Acceptable tem out of service Acceptable 3-12-83 Routine Mnthly Surv Acceptable 3-12-83 Routine Mnthly Surv Acceptable 25-83 Special--return to 3-16-83 Special--A D/ti out of service Acceptable service Acceptable 3-27-83 Special--test prior 4-10-83 Routine Mohthly and to alternate shutdown _

Special--after preven-testing Acceptable tative maint. Acceptable

'3-28-83 Special--prove oper- 4-30-83 Special--operability ability after alt, after air compressor shutdown testina Acceptable air line maint. Acceptable 3-29-83 Special--prove oper- 5-11-83 Routine Mnthly Sury Acceptable ability Acceptable

'4-20-83 Routine Mnthly and 6-9-83 Routine Monthly Acceptable Special--Operability after maint. Acceptable 5-1-83 Special--maintenance 6-13-83 Special Acceptable on LNP relay Acceptable 5-2-83 Special--test after 7-12-83 Routine Monthly Acceptable maint. Acceptable

1) due.to low Jacket coolant temp.

b APPENDIX A HISTORICAL SLM4ARY OF EMERGENCY DIESEL GENERATOR DEMANDS 1983.

(continued)

EMERGENCY DIESEL GENERATOR A EMERGENCY DIESEL GENERATOR 8 Date Reason for Demand Result Date Reason for Demand Result 5-3-83 Routine Monthly Acceptable 8-11-83 Routine Monthly Acceptable (3) 5-6-83 Special--Trouble Shoot Acceptable 8-26-83 Special-_ Failed 5-7-83 Special-test after .

8-27-83 Special--operability maint. on cool. sys. Acceptable followina repair Acceptable

~ 5--10-83 Special--test after .

9-6-83 Routine Monthly Acceptable maint. Acceptable 5-11-83 Special--test after 10-12-83 Routine Monthly Acceptable maint.- Acceptable 15-26-83 Special--operability 11-1-83 Special--CS-B out of after maintenance Acceptable service Acceptable 5-27-83 Special--Return to 11-8-83 Routine Monthly Acceptable service after jacket-coolant service water supply repair- Acceptable 6-7-83 Special--operability 11-30-83 Special--testing A test Acceptable D/G 00 S Acceptable 6-9-83 Routine Monthly 12-1-83 Special--test followinc (2) injector nozzle Failed replacement Acceptable

,6-13-83 Special Acceptable 12-6-83 Routine Monthly Acceptable 6-13-83 Special Acceptable 12-20-83 Special--prior to removal of UPS from service Acceptable 6-15-83 Special--maint. Acceptable 12-21-83 Special--A UPS inop. Acceptable-7-11-83 Routine Monthly Acceptable 8-8-83 Routine Monthly Acceptable 8-26-83 Special--Alt. testino' Acceptable 9-6-83 Routine Monthly Acceptable (2) due to low Jacket coolant temp

_ (3) solenoid _ failure

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APPENDIX A HISTORICAL SLM4ARY OF EMERGENCY DIESEL GENERATOR DEMANDS 1983 (continued)

EMERGENCY DIESEL GENERATOR A EMERGENCY DIESEL GENERATOR B Date Reason for Demand Result Date Reason for Demand Result 10-11-83 Routine Monthly Acceptable 10-12-83 Special--return to l service Acceptable 1-83 Special--CS-B out of service Acceptable 11-8-83 Routine Monthly Acceptable 12-1-83 Special--operational-test after maintenance Acceptable

'12-5-83 Routine Monthly Acceptable 12-20-83 Special--prior to removal of UPS from Service Acceptable 12-21-83 Special--A UPS inop. Acceptable ,

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a  ? HISTORICAL SUWARY OF EMERGENCY DIESEL GENERATOR DEMANDS P

1982 EMERGENCY DIESEL GENERATOR A EERGENCY DIESEL GENERATOR 8

, Date Reason for Demand Result Date Reason for Demand Result

'l-13-82 Routine- Acceptable 1-12-82 Routine Monthly Acceptable 7

2-6-82 Special--UPS inop. Acceptable 2-6-82 Special--UPS inop. Acceptable 2-8-82 Routine Acceptable 2-9 Routine' Monthly Acceptable 2-11-82 Special--UPS inop. Acceptable 2-11-82 Special--UPS inop. Acceptable 2-23-82 Special--UPS inop. Acceptable 2-23-82' Special--UPS inop. Acceptable 2-24-82 Special--UPS inop. Acceptable 2-24-87 Special--UPS inop. Acceptable i

2-25-82 Special--UPS inop. Acceptable 2-25-82 Special--UPS inop. Acceptable 2-26-82 Special--UPS-inop. Acceptable 2-26-82 Special--UPS inop. Acceptable 2-27-82 Special--UPS inop. Acceptable 2-27-82 Special--UPS inop. Acceptable i .

2-28-82 Special--UPS inop. Acceptable 2-28-82 Special--UPS inop. Acceptable ,

, 1-82 Special--UPS inop. Acceptable 3-9-82 Routine Monthly Acceptable 4 Special--8 RHRSW work Acceptable 3-16-82 Special--UPS inop. Acceptable-9-82 Routine Acceptable 3-22-82 Special--UPS inop. Acceptable 3-16-82 Special--UPS inco. Acceptable 4-13-82 Routine Monthly Acceptable p 22-82 Special--UPS inop. Acceptable 4-24 Special--UPS inop. Acceptable L

Acceptable 4-12-82 Routine Acceptable 5-11-82 Routine Monthly 4-24-82 Special--UPS inop. Acceptable 6-9-82 Routine Monthly Acceptable 5-10-82 Routine' Acceptable 7-12-82 Routine Monthly Acceptable i

6-7-82 Routine Acceptable 8-9-82 Routine Monthly Acceptable

. 7-13-82 Routine Acceptable 8-10-82 Special--UPS inop.

and CS brkr swap Acceptable

' 7-15-82 Special--B RHRSW work Acceptable 8-16-82 Special--A D/t work Acceptable 8-9-82' Routine Acceptable 9-6-82 Routine Monthly Acceptable 4

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e, APPENDIX A HISTORICAL SU MARY OF EMERGENCY DIESEL GENERATOR DEMANDS 1982 (continued)

EMERGENCY DIESEL GENERATOR A EMERGENCY DIESEL GENERATOR B Date Reason for Demand Result Date Reason for Demand Result- ,_

8-10-82 Special--UPS inop and 9-8-82 Special--B RHRSW work Acceptable CS breaker swap Acceptable 8-11-82 Special--Return-to- 9-9-82 Special--B RHRSW t.ork Acceptable service . Acceptable 8-17-82 Special--Operability 9-10-82 Special--B RHRSW work Acceptable following repair Acceptable 9-6-82. Routine- Acceptable 10-5-82 Special--CS breaker

_r_emoval Acceptable

'9-8-82 Special--B RHRSW work Acceptable 10-12-82 Routine Monthly Acceptable 9 Special--B RHRSW work Acceptable 11-2-82 Special--after ACB maint. Acceptable 9-10-82 Special--B RHRSW work- Acceptable 11-2-82 Special--UPS inop. Acceptable 10-5-82 Special--CS breaker (4) 11-11-82 Routine Monthly Acceptable work Failed 10-5-82 Special--check slow . 12-7-82 Routine Monthly Acceptable starting time Acceptable 10-12-82 Routine Acceptable

.11-2-82 Special--UPS inop. Acceptable 11-2-82 Special--after ACB maint. Acceptable 11-11-82 Routine Acceptable 12-6-82 Routine Acceptable (4) Check valve in fuel oil return line - Failed resulting in excessive start time.

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APPEf0IX A HISTORICAL SLM4ARY OF EMERbENCY DIESEL GENERATOR DEMANDS 1981 EMERGEN I DIESEL GENERATOR A EMERGENCY DIESEL GENERATOR B Date Reason for Demand Result Date Reason for Demand Result 1-12-81 Routine Monthly Acceptable 1-19-81 Routine Monthly Acceptable 2-16-81 Routine Monthly Acceptable 2-16-81 Routine Monthly Acceptable 3-16-81 Routine Monthly- Acceptable 3-16-81 Routine Monthly Acceptable 4-20-81 Routine Monthly Acceptable 4-20-81 Routine Monthly Acceptable (5) 5-18-81 Routine Monthly Failed 5-18-81 Special--A diesel inop. Acceptable

.5-19-81 Routine--after repair Acceptable 5-19-81 Poutine Monthly Acceptable 6-8-81 Routine Monthly Acceptable 6-9-81 Routine Monthly Acceptable.

. 7-13-81 Routine Monthly Acceptable 6-9-81 Special Monthly Acceptable

.8-11-81 7-14-81 Acceptable Routine Monthly Acceptable Routine Monthly 9-9 Routine Monthly Acceptable 8-12-81 Routine Monthly Acceptable 10-12-81 Routine Monthly Acceptable 9-8-81 Routine Monthly Acceptable 11-1-81 Special--after maint. Acceptable 10-13-81 Routine Monthly Acceptable 11-9-81 Special--A D/C 00C Acceptable 11-11-81 Special--after maint. Acceptable 11-13-81 Routine Monthly Acceptable 11-12-81 Routine Monthly Acceptable 11-25-81 Special--after SW work Acceptable 11-21-81 Special--after SW work Acceptable

'12-4-81' Special--B RHR 00C Acceptable 12-4-81 Special--8 RHR 00C Acceptable 12-7-81 Routine Monthly Acceptable 12-11-81 Routine Monthly Acceptable

,(5) Failed gasket in cooling water outlet of cylinder #12.

,