ML20101N660

Forwards Response to 840702 Generic Ltr 84-15 Re Reduction in Number of Cold Fast Starts Surveillance Tests for Diesel Generators & Diesel Generator Reliability Data

ML20101N660
Person / Time
Site:	Fort Calhoun
Issue date:	12/28/1984
From:	Andrews R OMAHA PUBLIC POWER DISTRICT
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
GL-84-15, LIC-84-413, TAC-55860, NUDOCS 8501040149
Download: ML20101N660 (11)

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Omaha Public Power District 1623 Farney Omaha. Nebraska 68102 402/536 4000 December 28, 1984 LIC-84-413 Mr. Darrell G. Eisenhut, Director Of fice of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Division of Licensing Washington, D.C. 20555

References:

(1) NRC Generic Letter 84-15 dated July 2,1984 I (2) Letter from OPPD (R. L. Andrews) to NRC (Mr. D. G.

Eisenhut) dated August 6, 1984 (3) Letter from NRC (D. G. Eisenhut) to OPPD (R. L. Andrews) dated September 20, 1984 (4) Docket No. 50-285

Dear Mr. Eisenhut:

Diesel Generator Reliability Generic Letter 84-15 The Omaha Public Power District received the Commission's letter dated July 2,1984, (Reference 1). Accordingly, the District requested a time extension until December 15,1984 (Reference 2). This request was granted in Reference 3. Pursuant to 10 CFR So.54(f), 7 lease find attached, under oath or affirmation, forty (40) copies of the information requested in Reference 1. The information is presented as Enclosures corresponding to the Enclosures of Reference 1. The pertinent re quest is restated, followed by the District's response.

Recent telephone conversations were held with Fort Calhoun't /roject Manager (Mr. E G. Tourigny) to discuss problems which arose during the management review of this submittal. In some cases, additional review is being conducted. These items are denoted where appropriate in the 9501040149 841228 PDR ADOCK 05000285 P PDR jg3(/

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I ek) 6 as s:24 Employment th qual Opportunity A

r Mr. Darreli G. Eisenhut December 28, 1984 Page Two enclosures. If the results of the additional review alter any information presented herein, it will be submitted by January 25, 1985.

Sincerely, b l Yll R. L. Andrews Division Manager Nuclear Production RLA/DJM/rh-DD Enclosures cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.

Washington, D.C. 20036 Mr. E. G. Tourigny, NRC Project Manager Mr. L. A. Yandell, Senior Resident Inspector s

n UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of )

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Omaha Public Power District ) Docket No. 50-285 (Fort Calhoun Station, )

Unit No. 1) )

AFFIDAVIT R. L. Andrews, being duly sworn, hereby deposes and says that he is Division Manager - Nuclear Production of the Omaha Public Power District; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached response to Generic Letter 84-15 dated July 2, 1984; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, informttion and belief.

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R. L. Andrews Division Manager Nuclear Production STATE OF NEBRASKA)

) ss COUNTY OF DOUGLAS)

Subscribed and sworn to before me, a Notary Public in and for the State

! of Nebraska on this st./ day of December, 1984.

sentantseust-siseseasheste er a 1 .Y (/$)5%Notary Public

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Generic Letter 84-15 Enclosure 1 Reduction In Number Of Cold Fast Starts Surveillance Tests For Diesel Generators NRC Request - Fast Start Testing

" Licensees are _ requested to describe their current programs to avoid cold

- fast starts or their intended actions to reduce the number of cold fast surveillance tests from ambient conditions for diesel generators. Licen-sees are encouraged to submit changes to their Technical Specification to accomp1.ish a reduction in the number of such fast starts."

District's Response Late in 1983, the Omaha Public Power District received the Commission's Generic Letter 83-41, a request for information concerning the fast cold starts of diesel generators (i.e., starts with rapid acceleration and loading without prelubrication and wamup). In a letter dated January 6, 1984 (LIC-84-002), the District stated that the emergency diesel genera-tors at Fort Calhoun Station are provided with prelubrication and warmup capabilities. The District also stated that our diesels are kept warm and ready for starting by a water jacket immersion heater. In addition, a ,

lube oil pump circulates oil when the diesel is not operating. This oil is warmed by flowing through the lube oil heat exchanger. Based on these ,

3 reasons, we concluded our system did not experience cold fast starts and  :

1 that concerns expressed regarding cold fast starts of diesel generators

! affecting reliability and availability were not applicable to the Fort Calhoun Statior,.

7 Since that time, in response to NRC Generic Letter 84-15, the District-has had a number of conversations with the diesel engine manufacturer. These conversations indicate that our diesels are, in fact, subjected to cold fast starts. This is because our preheat and continuous lube oil pump do not eliminate cold fast starts. Based upon the conclusion that the Fort Calhoun Station diesels are, at this time, subjected to cold fast starts, the District responds to the NRC's request for infomation as follows.

Fort Calhoun Station's cold fast start surveillance testing program is

- based on the present Technical Specification requirements. The Technical l- Specifications require a monthly cold fast start on each of the two diesel generators when not in a refueling shutdown, following each diesel genera-i tor's ' annual- overhaul and prior to each reactor startup if not performed-j within the previous week. Please note that the diesel generators are

- equipped with a continuously operated engine warming and lube oil circu-lation system to help minimize the stresses on the system.

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- The present cold fast start program results in approximately 10 to 16 cold

~ fast starts per calendar year, depending on the length of the refueling outages, length of fuel cycle, and number of unit outages during the fuel-cycle. At-the present time, the Technical Specifications permit no reduc-tion in the cold fast start. test program.- The District' will investigate Technical Specification changes and will submit revisioas (if warranted).

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NRC Request - Other Diesel Generator Testing i The staff is also concerned about a number of additional diesel generator tests currently nequired by Technical Specifications of some of the earlier licensed plants. "The affected licensees are encouraged to pro-pose Technical Specifications to m>&a such changes."

District's Response Other testing of both diesel generators at the Fort Calhoun Station is currently required by the Technical Specifications and the Surveillance test program. The Technical Specifications require starting of at least one diesel generator (done to idle speed and not loaded) on loss of both

! auxiliary power transformers, loss of both house service transformers, loss of a-4.16 kV safety bus, loss of a diesel generator, or loss of containment cooling e cpipment. Additionally, a cold fast start is required as part of an undervoltage surveillance test in order to verify initiating circuits.

The District plans to review these Technical Specifications and the Surveillance test as a part of the effort described above for Cold Fast Starts. If any changes are believed to be warranted, they will be submitted.

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! Generic Letter 84-15

! Enclosure 2 Diesel Generator Reliability Data

NRC Request - Reliability Data

. Licensees are requested to report the reliability of each diesel generator at the plant for 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 whether they maintain a record which itemizes the demands and failures experienced by each diesel generator unit, in the manner outlined in Regulatory 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. Tne criteria for determining the reliability of diesel generators is as follows:

a. Valid demands and failures are to be determined in accordance with the recommendations of Regulatory 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."

District Response

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i The District compiled a listing of the operating history for the diesel generators at Fort Calhoun. As noted in the cover letter, this informa-tion is currently under review. This listing was compiled in accordance l with Regulatory Guide 1.108, Position C.2.e, with the following deviation:

A valid successful run was one in which the diesel was loaded

, to greater than 50% rated load for 40 minutes or more, and at 4 the end of the run was shut down voluntarily, not to avoid

. damage due to a component failure.

The deviation above was necessary in order to compile an acceptable number

, of starts as requested by the generic letter.- Data prior to 1977 were not included because operating procedures at that time did not require running the diesels more than 15 minutes. This produced misleading information

[ for that time period which did not accurately reflect reliability history.

l The reliability, utilizing criteria of Regulatory Guide 1.108 and the above stated deviation, yields figures of approximately 88.6% for DG-1 and 93.6% for DG-2. For the last 20 demands, the reliability was 90% for DG-1 and 90% for DG-2. The attachment to this enclosure summarizes the time

history and cause of the failures as currently reviewed. If any addi-tional information impacts the conclusions of this enclosure, it will be submitted by January 25, 1985.

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The District does not at this time maintain a record in the manner out-lined in Regulatory Guide 1.108, Position C.3.a. which itemized the demands and failures experienced by each diesel generator unit. At the present time we do not maintain a yearly report of each diesel generator's reliability. Upgrades to our methods of recordkeeping are under consideration and are discussed further in Enclosure 3.

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DIESEL'GENERAT0FrFAILURES DG-1 CAUSE 06/16/78 100 Amp Fuse Failure 07/05/78 Generator Exciter Malfunction 07/07/78 Exciter Control 08/09/78 Exciter Control 07/09/80 Transfonner- Failure 09/10/80 Transformer Failure 11/05/80 Relay Contact Stuck 12/11/80 Secondary Air Start 4

Motor Dirty 07/06/81 Speed Sensor Failure 11/11/83 Exciter Control Speed Sensor Controls 07/11/84 Governor Adjustment i DG-1 Valid Tests 96 Failures 11 DG-1 CAUSE l 11/27/78 Breaker Failure 01/22/80 Zener Diode Failure 01/22/80 Radiator Tube Leak 03/24/82 Coolant Leak 05/19/82 Pushbutton Failure 09/21/83 Exciter Control i

DG-2 Valid Tests 93 Failures 6 +

Attachment to Enclosure 2

Enclosure 3 Diesel Generator Reliability NRC Request - Reliability Improvement Program Licensees were requested to "... describe their diesel generator relia-bility improvement program, if any, for attaining and maintaining a

- reliability goal. The program description should address the surveillance and testing the licensee performs to demonstrate the selected diesel generator reliability. All licensees have received the staff's previous '

letter transmitting the findings of NUREG/CR-0660, identifying areas where diesel generator operational problems were occurring in general. Licen-sees should consider the results of NUREG/CR-0660 in their reliability 4

program. The staff has developed an example for a diesel generator reliability Technical Specification to support the mainte-nance of diesel

! generator reliability at a specified level. The proposed specification

encompasses certain aspects of the existing requirements for surveillance testing of diesel generators stipulated in Regulatory Guide 1.108, and the qualitative recommendations of NUREG/CR-0660. This performance specifi- t cation is presented, as an example, in the attachment. Licensees are  ;

i regested to comment on and/or compare their program with the performance j specifications and provide comments fo" staff consideration in finalizing surveillance testing repirements for diesel generators."

District's Response At the Fort Calhoun Station, the diesel generator reliability program consists of three parts: operational testing, annual overhaul, and failure i analysis. In addition, the District also has a fuel oil quality program.

, The operational testing is a monthly surveillance testing and check i program which verifies 10-second full-speed starts, manual starts,

, loading, and fuel oil transfer system. During each refueling the automatic operation, including sequencing of engineered safety features loads, is verified.

I The annual overhaul consists of maintenance, calibration, inspection, and l operation. Recommended maintenance is performed; i.e., filter change out l and lubricating oil analysis as recommer.ded for standby service. Diesel generator instrumentation is calibrated and checked for proper operation.

The engine and generator are inspected for abnormal wear or deterioration.

After completion of the preceding three areas, the engine and generator I

are checked for proper _ operation; .i.e., overspeed test,10-second start, and proper loading.

The fuel oil analysis program includes the following:

1. Monthly sampling and testing of each diesel generator day tank.

2. Each incoming fuel oil-delivery.

3. Main storage tank - check for water every six months.

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A yearly log is not maintained for each diesel generator. The failure analysis is part of a station wide program to insure proper review and l disposition of failures of safety related equipment. The diesel generators are a part of the program.

The program is required by station Standing Orders, and is designated as an Operations Incident Report. This report insures proper notification, (including a License Event Report if required), a review by knowledgeable staff members, final disposition, and Plant Review Committee review. The District has recently computerized its maintenance history and is parti-cipating in NPRDS. This should enhance the ability to perform failure

! analysis using historical data.

Although Fort Calhoun maintains records in accordance with the Technical Specifications and Plant Standing Orders, a review of the District's failure data indicates that improved recordkeeping, maintenance history, and root-cause investigations would best improve reliability. This area will be investigated as part of the overall effort.

The District has reviewed NUREG/CR-0660 for applicability to the Fort

Calhoun Station diesel generators. In general, the District finds that the design complies with the recommendations provided. The District plans to study those areas which could improve the engine reliability and will implement those areas wherever practical.

i The District has reviewed the proposed diesel generator reliability i improvement Technical Specifications. The District believes that these j specifications are based on a specific design. It is the District's

! opinion that these specifications must to some degree be altered to accomplish diesel generator reliability improvement and accommodate the-station (unit) specific design basis.

The District believes that the reliability specification, as it addresses requalification (both increased testing and actual requalification for

, nuclear service), must be limited to those items which actually affect engine / generator operability and the failure of which is reasonably attributable to those stresses which would be expected under engine-start-ing and load testing. A more valid approach to the problem would be modifications to surveillance and maintenance requirements on failure-prone components. A case in point is the May 19, 1982 failure of the

local pushbutton. The engine / generator was still fully functional via the

' remote manual and automatic starts. NUREG/CR-0660 also points out the failure definition problem. No useful purpose will be served by running the diesel generator if the " failure" is due to the random failure of a control switch.

The District believes that the " root-cause" approach will have the most significant impact on reliability. This would address specific failures and improve reliability without causing additional challenges to the en-tire system. Increased frequency of testing should be used as a tool to find the weak link in the system only if repeated failures are suspect.

Some of these areas must be discussed in detail with vendors to ensure testing in fact improves reliability.

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The District also is concerned with the :se of present surveillance test-ing data to define the diesel generator' reliability as it relates to station blackout. The station blackout / diesel generator interaction does not demand the diesels be operable immediately; there is a two-hour period of time during which diesel generator availability is not essential. The test data for failures do not separate " repairable" failures from other fail ures. These failures should not be considred applicable for station blackout purposes.

The District would like to make one comment regarding the reporting l requirements. After the initial report, the District believes all re- 1

. porting should be done under either the present LER system or the monthly ,

operating report. The discussed information can be adequately addressed '

within the framework of either the LER system or the monthly operating report without imposing a new set of reporting guidelines.

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