ML20077R016

Proposed Tech Spec 3.7(1)a.i Amend Re Testing of Emergency Diesel Generators

ML20077R016
Person / Time
Site:	Fort Calhoun
Issue date:	08/12/1991
From:	OMAHA PUBLIC POWER DISTRICT
To:
Shared Package
ML20077R015	List: ML20077R008 ML20077R016
References
NUDOCS 9108220123
Download: ML20077R016 (6)

Text

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3.0 SURVEILLANCE REOUIREMENTS 3.7 Emercenev Power System Periodic Tests Appheability Applies to perimlic testing and surveillance requirements of the emergency power system.

Objective To venfy that the emergency power sys* '<ill respond promptly and properly when required.

Specifigations The following tests and suncillance shall be performed as stated:

(1) Diesel cenerators:

a. Each diesel engine shall be started at least once per 31 days on a staggered basis.

The engine shall be run with all protective devices operable. The test shall verify that:

i. The diesel starts and accelerates to ratal Ldle. speed.-and-voNge-m le* thunor aptal-to-4G+aend+r Followine a warm-up ceriod as recommended by tig manufacturer. the diewl cenerator will be accelerated to ratpl speed and voltace, N or mall y,--for-4he rt wpe w- e f- thburveilla nce- 64in gr 4hece -ditw l - genere tt+

start w-may-be-preenial- by-en-engine-pre-lubeterk*F-eml4v-other--warnac proeahwe+weom men ded--ky - t he- manu faci twer-* 4 hat - mechanical- +.t rtm - emi weamm-thevngmeMninimized2-llowever, at least once per 184 days in these surveillance tests, the-lGemd elkwl-genere tt++4a rt -s6il he performal- from-ambient emdition+(eold-+. tart b-the diesel cenerator shall demonstrate that it can be started and accelerated to rated speed and voltace in less than or eaual to 10 seconds without a prior warm-up.

The signal initiated to start the diesel shall be varied from one test to another to verify all manual and auto start circuits."'

ii. With the diesel running at rated speed and voltage, the generator shall be synchronized with the 4.16 KV bus and the diesel breakr c mamially closed from the electrical control board. The generator shall then be loaded to at least the continuous

• KW rating and run for at least 60 minutes before being off-loaded and the diesel breaker tripped.

b. The auto-start initiating circuit for each diesel shall be tested prior to each plant startup if not done during the previous week.

c. Tests shall be conducted during each refueling outage to denvmstsate the satisfactory overall automatic operation of each diesel system. This test shall be conducted by:

3-58 Amendment No. 41,111 910e220123 910812 PDR ADOCK 0500023_,3 F PDR

3.0 SUltVEII IMCILitL QUlltEMENTS 1

3.7 DncIgency Power System Periodic Tests Applicability Applies to periodic testing and surveillance requirements of the emergency power system.

OlstCliv.c To verify that the emergency power system will respond promptly and properly when required.

Soccifications The following tests and surveillance shall be performed as stated:

(1) Diesel gengtaleIS:

a. Each diesel engine shall be started at least once per 31 days on a staggered basis.

The engine shall be run with all protective devices operable. The test shall verify that:

i. The diesel starts and accelerates to idle speed. Following a warm-up period as recommended by the manufacturer, the diesel generator will be accelerated to rated speed and voltage.

However, at least once per 184 days in these surveillance tests, the diesel generator shall demonstrate that it can be started and accelerated to ratee speed and voltage in less than or equal to 10 seconds without a prior warm-up.

The signal initiated to start the diesel shall be varied from one test to ,

another to verify all manual and auto start circuits.m t

ii. With the diesel running at rated speed and voltage, the generator shall be synchronized with the 4.16 KV bus and the diesel breaker manually closed from the electrical control board. The generator shall then be loaded to at least the continuous

• KW rating and run for at least 60 minutes before being off-loaded and the diesel breaker tripped.

b. The auto-start initiating circuit for each diesel shall be tested prior to each plant startup if not done during the previous week.

c. Tests shall be conducted during each refueling outage to demonstrate the satisfactory overall automatic operation of each diesel system. This test shall be conducted by:

3-58 Amendment No. 44,i11 I

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ATTACHMENT B

DISCUSSION, JUSTIFICATION AND NO SIGNIFICANT llAZARDS CONSIDERATIONS Omaha Public Power District (0 PPD) is proposing to change Specification 3.7, " Emergency Power System Periodic Tests," to reduce the amount of fast starts on the diesel generators, in addition to the two (2) cold fast starts per year required by NRC Generic Letter 84-15, OPPD performs monthly fast starts following an idle run of short duration used to prewarm the diesel generators prior to the fast start. OPPD is proposing that a monthly idle start run followed by manual acceleration and loading replace the monthly fast starts required by Technical Specification 3.7.

Discussion and Justification for Changes to Technical Specification 3.7 (Specification 3.7(1)a.i.)

The surveillance requirements for the diesel generators are being revised to reduce the number of diesel generator fast starts. Diesel generator fast starts are a concern as they are believed to contribute to increased wear and equipment degradation. The surveillance requirements for diesel generator loads will remain the same.

As currently written Specification 3.7(1)a.i. requires that a fast start be

! performed on each diesel generator at monthly intervals. Two (2) of the fast starts are from ambient conditions which are required by NRC Generic Letter 84-15. l e remaining fast starts are preceded by a prelubrication l

and prewarming run and engine shutdown. The diesel generators are run unloaded to supply warm oil to prelubricate critical rotating components and to warm the engine to reduce mechanical stresses during the warm fast start. This current method of surveillance testing results in two diesel generator starts per surveillance test.

The proposed revision calls for the removal of the requirement to test the diesel generator on a monthly basis to start and accelerate to rated speed and voltage in less than or equal to ten (10) seconds. The justification for the reduction in testing requirements is that the governor eperation to increase speed and load can be demonstrated locally or in the control room. In addition, historical data have shown that the diesel generators rarely fail to comply with the ten (10) second criterion.

The proposed monthly requirement is to perform an idle start and then manually accelerate and load the diesel generators. An idle start is one in which the engine is started and operated at idle for a short time period (as recommended by the engine vendor) before being accelerated to rated speed and then loaded. This method allows the engine lube oil and cooling systems to stabilize prior to acceleration and loading.

l The diesel generator manufacturer states that the most desirable starting procedure is one which utilizes an idle start to allow temperatures to stabilize before loading. This method will reduce the test induced wear and equipment degradation to a minimum.

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' BASIS FOR N0 SIGNIFICAN1 flAZARDS CONSIDERATIONS The proposed changes do not involve significant hazards consideration because operation of Fort Calhoun Station in accordance with this change would not:

1. Involve a significant increase in the probability er consequences of an accident previously evaluated.

In order to ensure that the Diesel Generators perform as they were designed, it is important that they be tested on a routine basis; however, when testing becomec excessive the tests themselves can lead to test-induced wear and degradation, which could reduce the diesel generators reliability and availability. The proposed change to this Technical Specification provides for an overall reduction in diesel generator starts which is consistent with the intent of NRC Generic Letter 84-15 and other utilities' EDG Technical Specification changes that have been previously approved by the NRC. Since the proposed change will improve the overall reliability and availability of the diesel generators and each EDG (by itself) can satisfy the power requirements for the peak and long-term accident loads, the proposed change will not significantly increase the probability or consequences of any accident previously evaluated.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

No new or different modes of operation are proposed as a result of this change. The proposed change would reduce the overalI number of diesel fast starts and is intended to increase the overall reliability and availability of the diesel generators. Since the diesel generators will still be capable of performing their design function (with potentially increased availability) the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Involve a significant reduction in the margin of safety.

The proposed change does not reduce any margin of safety. The purpose of the diesel generators is to ensure there is sufficient power available to supply the safei.y related equipment reouired for safe shutdown of the plant and mitigation and control of accident conditions. The redundancy of the power sources required ensures that even during an accident with a coincident loss of offsite power and a single failure of one onsite power source, there is still sufficient power to supply all required safety systems. Since the proposed change has no effect on the Limiting Condition for Operation (LCO) these requirements are unaffected. In the event one emergency diesel generator is inoperable, Technical Specification 2.7(2) requires that J

all other A.C. normal and emergency power systems be operable and that all Engineered Safeguards on the operable bus supplied by the operable 2

J diesel generator be operable. This provides assurance that a loss of offsite power will not result in a complete loss of safety function of critical. systems during the time one EDG is inoperable. The proposed changes to the Technical Specifications should result in increased reliability and availability of the EDGs. The surveillance requirements are intended to demonstrate the operability of the A.C.

sources. There have been no changes to the surveillance requirements affecting the operability of the offsite A.C. sources. The proposed changes will reduce the overall wear on the diesel engines.' This should result in an increased reliability of the EDGs. Therefore, due to the increased reliability and availability of the EDGs, the of safety. change does not involve a significant reduction in the margin proposed Therefore, based on the above considerations, OPPD does not believe that this pro >osed defined )y 10 CFR amendment involves a significant hazards consideration as 50.92 and the proposed changes will not result in a condition which significantly alters the impact of the Station on the environment. Thus, the proposed change meets the eli categorical exclusion set forth in 10 CFR 51.22(c)(9)gibility criteria and pursuant to 10for CFR 51.22(b) no environmental assessment need be prepared.

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