PNL-6287

Technical Evaluation Report

Study Group Review of

Nuclear Service Diesel

Generator Testing and Aging

Mitigation

K. R. Hoopingarner

B. 3. Kirkwood

P. J. Louzecky

March 1988

Prepared for

the U.S. Nuclear Regulatory Commission

Office of Nuclear Regulatory Research

Division of Engineering

under Contract DE-AC06-76RLO 1830

NRC/RES FIN 2911

Pacific Northwest Laboratory

Operated for the U.S. Department of Energy

by Battelle Memorial Institute z

0 Baleileu
PNL-6287

TECHNICAL EVALUATION REPORT

STUDY GROUP REVIEW OF NUCLEAR

SERVICE DIESEL GENERATOR

TESTING AND AGING MITIGATION

K. R. Hoopingarner

B. J. Kirkwood af

P. J. Louzeckyja

March 1988

Prepared for

the U.S. Nuclear Regulatory Commission

Office of Nuclear Regulatory Research

Division of Engineering

under Contract DE-AC06-76RL0 1830

NRC/RES FIN 2911

Pacific Northwest Laboratory

Richland, Washington 99352

(a) Independent consultants.
ABSTRACT

As part of the Nuclear Plant Aging Research (NPAR) Program, the Pacific

Northwest Laboratory is performing a Diesel Generator Aging Assessment Study

for the U.S. Nuclear Regulatory Commission. In the on-going NPAR Phase II of

the aging study, efforts have been focused on aging mitigation and other

success strategies for improving nuclear plant diesel generator operation and

maintenance.

A study group of diesel experts, the authors of this report, met on

April 29 and 30, 1987, to resolve issues on diesel generator aging mitigation

and improved operations, testing and maintenance. This report documents the

conclusions and recommendations of the study group. If these recommendations

are put into practice, the experts agreed that many of the engine aging

stressors could be either eliminated or their effects could be managed to

reduce failures.

The focus of the study group was to 1) address the diesel generator aging

stressors resulting from the present nuclear industry testing practices, and

2) propose potential mitigating measures. A new recommended testing program

was developed and is documented in this report. It appears that, if implemented, the recommended program could greatly reduce the fast-start aging

stressor and improve the operability and reliability of diesel generators.

iii
CONTENTS'

ABSTRACT ...................... iii

1.0 EXECUTIVE SUMMARY AND GENERAL BACKGROUND ...... ..................... 1.1

1.1 EXECUTIVE SUMMARY .............................................. 1.1

1.2 BACKGROUND ....... ........................................... 1.3

2.0 TESTING AND INSPECTION .. ..................... .................. 2.1

2.1 TESTING AND INSPECTION ASSUMPTIONS .......................... 2.2

2.2 TESTING RECOMMENDATIONS ...... 2.3

2.2.1 Periodic Testing Recommended ............................ 2.3

2.2.2 Engine Test Starting and Loading ....................... 2.4

2.2.3 Engine Test Operation ................ ...... o......... 2.5

2.2.4 Testing After Specific Faults and Maintenance ... ..... 2.6

2.3 INSPECTION RECOMMENDATIONS ...... .............................. . 2.6

2.3.1 Weekly Inspections .......... .. .. ...... .. .. .. .. ... .. .... 2.7

2.3.2 Monthly and Quarterly Inspections ..... ................. 2.7

2.3.3 Yearly or Refueling Outage Inspections ................. 2.9

3.0 MONITORING AND TRENDING .... oo ............. 3.1

3.1 MONTHLY MONITORING ... ..... .............. ........... 3.4

3.2 OTHER PERIODIC MONITORING ........................ ............. 3.6

3.3 TRENDING .. ............................. 3.6

4.0 MODIFICATIONS, TRAINING AND MAINTENANCE ............................ 4.1

4.1 MODIFICATIONS ........ oo ........................ 4.1

4.1.1 New Modifications Recommended .......................... 4.1

4.1.2 Optional Modifications .................. ......... 4.2

4.2 TRAINING ........................... 492

v
4.3 MAINTENANCE ............... ... o.......................

4.3

5.0 REGULATORY MONITORING ACTIONS RECOMMENDED ........................... 5.1

5.1 REGULATORY CONCEPTS ....*............... 5.1

6.0 REGULATORY GUIDES AND STANDARDS ............................. 0....... 6.1

REFERENCES ............................... .......... *** ................ R.1

APPENDIX A - RECOMMENDED DIESEL GENERATOR MONTHLY TEST PARAMETERS ....... A.1

APPENDIX B - RESUMES ........................... B.1

APPENDIX C - WORKSHOP AGENDA ............................... C.1

APPENDIX D - U.S. NUCLEAR REGULATORY COMMISSION REGULATORY GUIDE 1.108 55 D.1

vi
FIGURES

3.1 Mechanical Failure Pattern 1, Representing Only 8% of the Components Studied. Failure Rate Reduction Due to Maintenance. ........ 3.2

3.2 Mechanical Failure Pattern 2, Representing 11% of the Components

Studied. Early Maintenance Benefit Only. ......................... 3.2

3.3 Mechanical Failure Pattern 3, Representing 15% of the Components

Studied. Maintenance Does Not Affect Failure Rate. ............... 3.3

3.4 Mechanical Failure Pattern 3, Representing 66% of the Components

Studied. Maintenance Increases the Failure Rate. ................. 3.3

vii
'.1.0' EXECUTIVE'SUMMARY AND GENERAL BACKGROUND

Pacific Northwest Lab)oratory (PNL)was-selected to participate'in the

Nuclear Plant Aging-Research.(NPAR)-Program 'by the Nuclear'Regulatory Commission's (NRC) Office of Nuclear Regulatory'Research, Division of Engineering.

The results of the completed Phase I diesel generator aging research are documented in a two-volume report (Hoopingarner et al. 1987). In the Phase I

research, plant operating experience, 'data,-expert opinion and statistical

methods'were used.to produce'a'new 'data base.related to aging; reliability

improvement, and operational'readiness'of nuclear service diesel generators.

1.1 EXECUTIVE SUMMARY

.A study group of diesel.experts met to resolve issues, on aging mitigation

'and operational. 'readiness and this'.report.documents the meeting results. The

effects of'agin'g,'on diesel generator operational readiness-are an important

safety -consideration 'for ,nuclear p'oweristationis. ".The'diesel 'generator experts

and the PNL staff that' comprised.the'study-group have manylyears of indepth

experience and two years of experience on .the;'NPAR diesel.'aging 'research task.

This experience enabled them to review the6'testing, aging and regulatory 'areas

and to make recommendations regarding.changes in these-aspects of the program. The study group 'concluded 'that much new' information,' collected or developed during the'NPAR aging research task,'provides a basis to'recommend 'and

defend'a new approach-an'd concept'for 'diesel 'generator'testing that.,potentially

improves 'reliability. ''The information sand data presented in this document

appear to have'.direct applications to diesel 'generator regulatory.guide revisions, the' station-blackout issue ,OJS1-A-44) and the reliability issue

(GI-B-56). ' .

With the new leak-before-break regulatory determination for large bore

reactor piping and other studies,'it is increasingly difficult to justify the

typical 10-12 second diesel engine fast starting requirements. This issue is

discussed further in' Section 2.0. 'The experts concluded that much aging

related'wear'and'severe engine 'service-'conditions could"b'e'avoided'if the

engine LOCA'emergency starting' mission requirem'ents were adjusted to'a'30 to

60 second range. The conservative' position for overall safety 'appears' to favor

the longest time period that can be supported by plant type (BWR, PWR) calculations. This'relatively small,'increa'se in the start time,'results in many significant advantages, the most important being'improved mnission'.reliability and

mitigation 'of aging effects.'' Further advantages accrue'if routine test''starting and engine loading sequences and, non-LOCA emergency.starting time-requirements are 'extended 'even more than one minute.' 'Thedrexperts.recomme-nded that

plant.technical specifications, 'regulat6ry 'guides,' IEEE.codes 'and other related

regulatory documentation should'be' modified to permit 'more 'appropriate'starting

and engine loa'ding' requirements. ' ' '

This Technical Evaluation Report-*is organized'into separate topics which

follow the agenda of the study group workshop.' However, for the'regulatory

perspective of improved requirements, this separation is not recommended. One

'1.1
I

integrated program is recommended for diesel generator management. This program would integrate testing, inspection, monitoring, trending, modifications,

training and maintenance of the emergency power units. The recommended integrated program is similar to the overall program already in place at many of

the small nonnuclear diesel powered electrical utilities operated by some

municipalities. Subject to regulatory constraints, many nuclear stations also

have some recommended elements in place.

The proposed overall diesel generator program would be relatively easy to

establish and it is'practical for long term results. It is based upon nuclear

and nonnuclear industry experience and results in the elimination of certain

aging stressors. 'The proposed program places this area of safety responsibility directly on the licensees, similar to all other safety issues within

nuclear power plants. The regulatory role taken by the NRC should be typical

of the role it takes for other plant standby safety equipment.

The proposed program has evolved from research directed to the determination of diesel generatoraging under the NPARprogram. However, aging mitigation improvements also result in reliability improvements and have other

positive NRC and industry influences. For this report no attempt was made to

restrict ideas to aging, NRC'responsibilities, or other issues. Key elements

of the recommended program are 'shown below:

' It is proposed that the focus of the regulatory assurance of the

diesel generator safety function be changed froma statistical basis

of successful monthly-fast starts to a more predictive monthly testing program.' The'recommended monthly program is intended to test,'

monitor, trend and thu's 'predict system operability and absence of

aging deterioration.' A slower starting schedule is defined for the

engine monthly tests which are intended to obtain operating data on

about 50 parameters that indicate engine operability status. The

test schedule recommended is defined in Section 2.0, and the parameters are defined in Appendix A of this report.

-It isintended that the licensees develop practices for testing,

inspection, monitoring,'and trending into an'integrated program for

better diesel'engine performance and less risk from aging and wear.

The general outline is detailed in this report.

It has been shown in the NPAR diesel aging research and studies that

improved training and better maintenance also reduce the risk of

deteriorating safety performance by aging and wear and other factors.

* It is proposed that a submittal of the total diesel generator program

be prepared for, NRC review. Regulatory overview would be based on

performance and would parallel the approach for'other plant standby

safety equipment. 'The NRC would monitor how well the utilities operate according to their submitted program commitments. The requirements of Regulatory Guide 1.108 would need to be modified to reflect

the new recommended regulatory monitoring and monthly testing

requirements.'

1.2
1.2 BACKGROUND

The Phase I research defined which diesel generator components fail and

the principal causes of failure. This research also indicated that present

plant practices and regulatory requirements for diesel generator testing and

periodic engine disassembly are not achieving the desired aging mitigation and

reliability goals. The fast-start testing requirements, outlined in Regulatory

Guideline 1.108 and plant technical specifications, with its statistical basis,

have no predictive capability nor do they measure deterioration, or aging, of

the system. In fact, a fast-start test itself may consume the remaining capability of a system component. For example, a starting system component may

energize initially and function, but burn out or plug or fail just as the

engine fires up and starts to run. For this example, this system component

only had to work for 1-3 seconds and the engine operators would have no indication of subsequent failure. Consequently, a subsequent valid emergency

demand would not result in a start and run because of the undetected failure.

Therefore, a condition-monitoring method that improves on the current diesel

generator testing practice is needed.

One approach used in the ongoing Phase II research to resolve the general

issues of aging mitigation and engine failures was to convene a study group.

The group consisted of the authors of this report, who had worked on the Phase

I research and other previous NRC diesel programs. Appendix B lists the qualifications and affiliations of the expert consultants under contract to PNL.

The goals of the study group were to develop a broad scope of practical recommendations with good potential for mitigating aging effects. In addition,

guidelines to improve diesel-generator operations and maintenance with emphasis

on aging concerns were to be considered, including recommended changes to

Regulatory Guide 1.108.

This report documents the conclusions and recommendations developed by the

study group in a meeting held on April 29 and 30, 1987 at Buena Vista,

Colorado. Previously documented information, data and discussion material

necessary to introduce and understand the issues and the recommendations are

also included in the report.

1.3
2.0 TESTING AND' INSPECTION'

The' original-basis of the diesel generator testing requirements'is discussed in Regulatory Guide 1.108, A. Introduction and B. Discussion. The fast

start requirement and reliability goal of 0.99 (at a nominal 50% confidence

level) are further'defined in'the NRC Standard'Revie4' Plan, and regulated

through the plant'technical specifications documentation. 'The Code of Federal

Regulation, 10 CFR Part 50 and appendices,'further defines the basis and

requirements for diesel generator testing. :Should the number of failures to

either start or run exceed 1 in 100 tests, the test interval progresses in

4 steps from 31 days to 3 days for 4 or more failures, as'defined in'Regulatory

Guide 1.108,' Section C.2.d. '' -

When issued in 1977, Regulatory'Guide 1'.108 appeared to represent a reasonable and conservative basis for regulation, since the nuclear industry had

limited experience with' these machines.: IHowever, in 'recent years,-accumulating

evidence indicates that'the large-'number of tests, and'the-fast starts in particular, are accelerating the engine-aging' process. In 1984, the'NRC encouraged nuclear plant owners to request-testing changes by issuing'Generic Letter

84-15. The intent of this 'letter was to reduce the'number of cold'fast'starts

and to provide relief from excessive testing-on earlier"licensed'plants.

Information 'from research' studies', otperating experience, workshops diesel

experts and diesel' engine 'disassembly and examination'have shown'that the faststart testing is ai'ajor.a'ging st'ressor, and does little to'ensure'future

engine operability. J Th'e'engineistart'time-is not given in Regulatory

Guide 1.108, which references the technical specifications for each nuclear

plant to be used for spe'cifying the diesel start'time. These typically are in.

the order of. 10-12 seconds depending-upon the'assumptions used'for the specific

plant LOCA analysis coupled-with'loss of 'offsite power'.'' Fuel cladding-temperature calculations which are defined in 10 CFR 50,'Appendix K, are part of the

plant analysis used for determining the diesel generator start and loading

time. These very conservative cladding temperature calculations also were used

to develop the 10-12 second start time range. The fast start is a very severe

engine stressor when followed with the typical loading sequence time frame of

30 to 45 seconds to achieve' full load.'

The possibility for safely increasing the prescribed start time of the

diesels is increasing. *Some of"the reasons for the various regulatory" changes

being proposed or considered at'this time"are: -

* A major change has already been made to 10 CFR 50, General Design

Criterion 4,' which'accepts-'le'ak-b'efore'-b'reak analys'is 'and 'detection

methods fo'r' tie''primiary large' bore' piping. "Extension to equipment

qualification and diesel start time requirements is being considered,

but no newcriteria have been formulated or released.

.; . . , ..

(a) The reference list, page R.1 of the report documents the information

cited.

'2.1
I

;.

* Studies documented by EPRI and others show that the safety function

emergency power requirements for the diesel generator system are on

the order of 1 to 2 minutes for a LOCA event with a loss of offsite

power and 5 minutes, or more, for a loss of offsite power event without a LOCA. (EPRI'1986 a,b)

* The calculational methods of 10 CFR 50, Appendix K, have been shown

to be overly-conservative, based upon the latest information and computer program models. EPRI and other organizations are performing

these new calculations (EPRI 1986 b).

- In view of the above discussion and referenced material, it seems reasonable to propose that the emergency power mission requirements be reviewed. A

more conservative approach for reduction of aging effects and increased reliability is to define the recommended mission as follows:

1. The onsite emergency power is needed in the time frame of about

60 seconds, assuming-both loss of offsitepower and a large bore LOCA

event, with a recommended engine start time of about 30 seconds. The'

exact time permitted would depend upon plant specific analysis, but

the conservative position is to permit as much time as can be justified to avoid abnormal aging.

2. The onsite emergency power is needed in the time frame of 2 to

10 minutes,-assuming a simple loss of offsite power. Again specific

plant analysis would be the basis for this mission loading time. The

conservative position in this case is closer to 2 to 3 minutes.

3. For testing purposes, the test mission, or schedule, recommended is

to test monthly with a'10 minute ramp up to full power (see section

2.2.1) and semi-annually with the shorter time period typical of the

large-LOCA event requirements.

2.1 TESTING AND INSPECTION ASSUMPTIONS

The diesel experts involved in the study group were given the following assumptions:

1. For routine testing, the diesel start time should be open to

change. The study group may include a new recommended time for

consideration

2. The testing frequency and other parameters of Regulatory Guide 1.108

should also be considered to be equally open for discussion and

resolution.

3. Comparable utility practices and manufacturer's recommendations

should be treated as potential areas of improvement for aging

mitigation.

2.2
4. Changes to engine designs-or extensive modifications*to the engines,

systems, or plant structures-were not considered to be the-best

approach to the diesel -aging:concerns- and were found to be-not significant-in PNL's Phase 1'research (Hoopingarner et. -al. 1987).

Therefore, design and major modification:changes were not considered

as a part of the recommendations by :the study group, and in any case

would be outside of the-scope of the NPAR Program.

2.2 TESTING RECOMMENDATIONS

The testing recommendations were extensively discussed as to value, predictability, influence on-safety function,,aging limitations and other concerns. The resulting testing-recommendations from these experts are documented

in-this section. The group -decided that the:testing requirements of Regulatory

Guide 1.108 should be-improved, based upon'the abnormal aging and wear presently-experienced.' This is-further documented in Section 3.0 and 5.0 of this

report.; The group-now recommends'that-new regulatory guidelines should be

developed that-reduce the fast start-stressors and wear. These general

requirements are identified-in Sections-5.0 and 6.0 of this report.

2.2.1 Periodic Testing Recommended

The diesel experts agreed'that there should be no harmful effects of,

monthly surveillance-testing of-the diesel engines, provided-that the recommendations outlined-in this document-are'followed.- Fast start testing has been

identified as an"aging stressor,'especially after long shutdown periods, and

should be reduced (Hoopingarner et al. 1987). The approach of the-monthly

testing should-be-changed from the statistical-basis-implied in-Regulatory

Guide"1.108-to-a'new goal of determininig surveillance-information on the operating engines.' This-information is discussed further in paragraph 2.2.4-and in

Appendix A., For operator training and familiarity, monthly runs of approximately 12-14 hours are recommended, so that 3 work-shifts may be involved.

A start-run-stop routine on each shift.-is helpful also.-

The new purpose of monthly surveillance testing should be to obtain data

on key engine performance-parameters that indicate that the-trends in the -

engine performance are-normal,-or that some-certain indicator(s) may be revealing a future engine problem. The complete recommended listing of these data

points is-shown-inAppendix-A.- Section 3.0 further discusses the data-to be

obtained and which parameters are to-be monitored'and-trended. Where pressures

and temperatures'-are listed for-this'surveillancektest, and-appropriate instrumentation is notl-installed,;local -or--point-of-measurement-instrumentation is

intended. -The point is that'the operators-should be-at the engine observing

the operation and becoming familiar with-the. sights, -sounds, and feeling of the

engine at operating speed and loads. Taking the required measurements at

1 hour intervals will assist this process of developing familiarity.

Periodic--refueling outage testing should include a 24 hour test -run which

would include a 110% of contract load test for a 2 hour period. This type of

test, outlined in Regulatory Guide 1.108 [2.a.(3)], checks the cooling system

2.3
performance, the fuel system, engine aspiration, turbo charger and several

other components. When properly run, this test should have little or no

adverse affect on the engine or generator. If LOCA design considerations are

retained, a fast start and load test may be performed on an annual, or semiannual basis. Such a test should be followed by at least a 2 hour run at 75%

or greater engine load, to permit engine thermal stresses to be relieved.

Fast-start load testing more than twice a year should be avoided to mitigate

that aging stressor. Slower starts and loading adequately check the engine and

generator systems.

2.2.2 Engine Test Starting and Loading

The present engine fast start preoperational and monthly test program

should be modified to reduce the engine aging stressor from that source. It

was determined by the experts that a slower starting sequence, outlined below,

was equally good at detecting engine problems in almost every-instance considered and for each of the failure types discussed. The diesel experts

believed that the ultimate regulatory goal of increased diesel reliability

would be significantly improved, if the aging effects of the present fast start

testing were replaced by an improved test-monitoring-maintenance program. Such

a program is defined and recommended in Section 3.1.

For the monthly testing, any maintenance testing and the majority of the

preoperational testing the start-sequence should be a gradual increase in load

over an approximate 10 minute time period. This is typical of the way in which

diesel engines, are started in normal small utility operations. In these nonnuclear applications, it is not unusual to experience over 100,000 hours of

operation in a 35 to 50 year period of use, with 20,000 or more hours between

major overhauls. If an engine has not been fast started by a reactor operational response signal in a six month time period, it may be fast-start tested,

chiefly to check that the loading sequence circuits operate within acceptable

limits and time. An alternate procedure of electronic sequence checking may

also'be acceptable. If the LOCA event is removed as a design consideration,

then all fast start testing should be eliminated. Engine starting should be

according to the following recommended considerations.

1. For testing purposes, the engine should be started and idled for a

few minutes while checking for correct parameters and unusual engine

noise levels. The engine should not be idled-at or near a serious

torsional critical speed. (See item 4). Up to 1/2 hour in this idle

mode appears safe for all engine types. However, 5 to 10 minutes is

recommended and is-adequate for checking most engines and the key

parameters of interest. Owners of 2-cycle port scavenged engines

need to limit idle time to avoid exhaust manifold fires, and the

10 minute period is a more appropriate maximum for these engines.

2. The engine should be brought up to speed and loaded over a time

period of about 10 minutes to achieve full load. By idling for a few

minutes, and-gradually loading the engine in this way, the piston and

cylinder liner may thermally expand together and greatly reduce the

2.4
wear rates on the components. Other abnormal aging stressors are

also reduced by this slow-loading sequence.. -

3. For regulatory purposes, full load on-the engine-should be defined as.

the plant design load and any modifications-to that load. 'This

design load is'about-75% to 90%-of'the engine.rated-capacity. This

design load is documented-as the engine "Contract Load," which is

written into the purchase specification:and the-engine technical

specifications. -Testing at 110%.of full load should then,-be based on

-this'contract or-plant load.. The engines-should not .be started for

test' purposes and run immediately up'to-110% of thecontract load.

' Stability should be achieved-first at the contract load, see paragraph 2.2.3.- -'

4. A torsional analysis should.'be made and'verified.by test foreach - engine type and model similar-to that made-by.the Transamerica

De Laval Incorporatedi-(TDI) Owners'Group for those engines (PNL

1985). Plant procedures should then indicate-where these engine,-

torsional vibration critical-speeds:-are.located. For routine starts,

'the accelerating engine should -Pass through.these critical speedsquickly, but not at full fuel rack setting, i.e. not at maximum

acceleration.

2.2.3 -Engine Test Operation

.It is-the opinion of the diesel experts that there are-certain benefits in

increasing the engine operating-time period. The concept of stability is one

of the' significant considerations. ! Most'importantly, it allows the engine to

achieve stable conditions throughout all components.and systems.. This alleviates many stressful conditions and permits detection of developing abnormalities. Operator training and operating procedures should emphasize that certain

engine key parameters, chiefly pressures and temperatures, should be monitored

for stability, before changing engine loads under test 'conditions.- For -

example, after loading, cooling~water-temperature should increase to an acceptable level and then level-off .within a short-time, indicating stability forthat' parameter. This stability time period varies by parameter and engine

type, but is usually within'several-minutes. An engine should not be test

loaded to full-load or overload until-stability at lower loads is-verified.

After an'engine fast.start with full..loading, overload testing,'or other

unusual'condition whereby the engine is subjected to high thermal-transients,

the'engines should be operated for a period of at least 2,hours at or near

design-load conditions. -The benefit' of such operation.is to allow engine

thermal stresses':to :equalize 'and relax..-This avoids distortion, metal creep,

and other problems.

- Additional general benefits of longer routine test operations are to dry

out moisture in'the lubricating oil, to -circulate and consume fuel oil, to help

-avoid certain 'fuel oil aging problems-and to acquaint the operators with normal

engine operation and sound levels.- Sometimes operators or management have the

misperception that diesel engines are- delicate machines. Routine operation for

2.5
longer time periods should help develop the correct concept that diesel engines

are designed for reliable long-term operation.

2.2.4 Testing After Specific Faults and Maintenance

The present general practice is to fast start the engine after a malfunction and/or any significant maintenance, to ensure engine operability. Because

of aging concerns, the-experts did not agree with this practice and believed

that other tests or requalification measures were often superior for this purpose. For example, malfunctions attributed to human error or a clearly defined

fault should only require the specific correction for the error or fault and an

appropriate local component test. Maintenance on a specific engine system or

component should only require a subsystem or component test to ensure operability. In both of these examples, the engine should not always be started for

testing. This implies that the diesel generator owner has carefully trained

operators and maintenance personnel, and has procedures and a quality assurance

program that'are effective.- The clearing and removal of electrical and mechanical safety isolation points and valve closures performed for maintenance must

be meticulous, and where possible, local tests should be performed to ensure

operability of the system or component before returning the diesel generator

system to operational status.

In cases of major engine rebuilding, where highly stressed rotating or

moving components are replaced (crankshaft and crank rods,-for example), the

engine should be operated up to a minimum of 3 x 10 cycles at design loads

before the engine is returned to full operational status. A load cycle is

assumed to be RPM/2, for a 4-cycle engine. Engine cylinder liners, bearings

and generally pistons are not considered to be highly stressed, for example,

and would be exempt from such fatigue proof-testing.

2.3 INSPECTION RECOMMENDATIONS

Diesel engines used for marine and conventional stationary power applications receive weekly,-monthly and yearly inspections, each with different

goals and completeness. Diesels used for nuclear emergency power applications

were perceived to be used only a small fraction of the time and so typically

less'inspections were scheduled and performed. The aging research program for

diesels has developed information and data to support the concept that the

nuclear-station application, with the present testing requirements, is in

reality severe service' for the engine and several of the engine support

systems. Thus, a more complete inspection program appears to be appropriate

and should help mitigate certain aging failure processes and increase the

engin'e start and run reliability. Note that additional monthly and yearly

monitoring requirements are discussed in Section 3.0 of this report.

The weekly and monthly inspections should be made at the same time and by

the same personnel'who have the preventative maintenance responsibilities for

the diesel generators. The yearly, or outage, inspection team should have, in

addition to the preventative maintenance personnel, a plant engineer, manufacturers' representatives or an outside consultant to assist in the inspection.

2.6
All inspections should be documented, should follow a-written checklist and

should be signed off according to the plant quality assurance program for each

level of inspection.

2.3.1 Weekly Inspections

In general, the inspections should follow the good practice standards for

conventional diesel generator. systems and.the manufacturer's.recommendations.

The inspection personnel should check for oil and water leaks, other;signs of

vibration-induced loosening and the environmental stressor conditions identified in the aging research (Hoopingarner. et al. 1987.). 7Such stressors collectively represent the'causes of over 40 percent of the diesel failures. In

addition, the inspection/preventative maintenance personnel should.poil the

engine governor and fuel linkage and check for free operation and movement. To

complete the weekly inspections the following points should be included in the

plant inspection'program:-

* engine keep-warm system for oil/water heating for correct operation

and-the temperature specified

* lubrication oil levels; engine, governor, turbocharger and outboard

bearing

* engine prelube system for correct oil:level or pressure

* engine cooling system, valve alignments and in some cases radiator

levels '

* other valve alignments, especially after any maintenance has been

performed, which would-require isolations to.be-performed

* breaker alignments and relays, especially after maintenance periods

* air start system pressure, system moisture downstream of the dryers

and valve alignment.

2.3.2 Monthly and Quarterly Inspections'..-

These inspections probably have the most value If-they are scheduled to

closely'follow the `scheduled test-start-run operating, period. Signs-of vibration-induced'loosening and problems associated with environmental stressors may

be dete'cted before they'have'time to progress to a more serious condition or

failure mode.

*: Preventative maintenance and-inspections.,should focus on those systems,

subsystems and components identified in' the diesel .generator.aging research

(Hoopingarner et al. 1987). For example, the instrument and control'system and

the governorish6uld receive-special attention, since they are the system and

component with 'the most :failures. j The 'diesel 'generator support systems should

receive more attention than the diesel power train or the generator unit since

-2.7
the aging report (Hoopingarner et al. 1987) shows a much higher failure rate in

the support systems compared to either the engine or the generator.

Some monthly inspection items should be done while the engine is running. Inspections should include, but are not limited to, the following significant items:

* Check the air filters and the louver systems in the combustion air

and cooling-air systems.

* Check the fuel oil dual filter manual valve position. The valve

should not be in the middle position, but should be directing the

flow to one specific filter element. The other element should be

held in reserve for failure recovery and emergency use.

* Check for vibration loosened components or vibration induced damage.

* If a lube oil 'filter is changed, sample the surface deposits and cut

open the filter and inspect it for unusual contamination and wear

particles.

* Check diesel exhaust system for signs of leaking (engine running).

* Check diesel exhaust smoke color, at midpoint of the monthly test

run, or smoke meter reading (engine running).

* The monthly inspection should include the weekly inspection items and

should replace one weekly inspection.

The quarterly inspections and preventative maintenance should include the

following:

* Clean and inspect the strainers and filters in the starting air

system.

* Sample fuel oil in storage for jelly and gum formation and bacteria

growth at any condensate fuel-oil interface.

* Sample lubrication oil for wear particles, water contamination and

oxidation. Pentane insolubles should not exceed 4 and the Ph should

not be below 4 nor above 7. The amount of silicon in the oil, above

the original level (Silicon Fluoride anti-foam agent), is dirt contamination and is abrasive.

* Inspect the fuel oil filters and replace at the recommended frequency

or as shown by the' station experience.

' Inspect the'combustion air and exhaust manifolds for oil and carbon

deposits (fire hazard). Two-cycle engines especially benefit from

this inspection.

2.8
* Inspect relay enclosures and control cabinets for dust and dirt and

remove it where necessary.

* All diesel generator skid-mounted equipment should receive at least a

visual check for vibration damage and loosening. Valve operators,

instruments, equipment mounts, fittings and other important equipment

should be checked, especially those items which have failed in the

past from this engine stressor. Checks with the engine running are

also beneficial for vibration damage or loosening.

2.3.3 Yearly or Refueling Outage Inspections

The refueling outage inspection goals should include a significant review

of previous local engine failure points, and should cover the manufacturer's

recommendations for inspection and any special tests and inspections needed to

resolve any diesel generator monitoring adverse trends or other indication of

problems. The study group recommended that an expert diesel consultant, a

manufacturer's representative, or a well-qualified utility staff engineer provide technical direction and assistance for the yearly inspection effort.

A diesel generator unit that is being effectively monitored and inspected

should not be disassembled simply to inspect it for potential aging and wear.

Since the probability of inducing a potential failure is at least as high as

the potential of discovering any latent defects, the diesel experts could not

recommend significant engine disassembly for inspection purposes. Instead,

they recommended an effective monitoring and trending program, such as

described in Section 3.0 of this report, which should be more effective in

identifying deteriorating engine conditions than engine disassembly and

inspection.

The yearly inspection should include the following items to achieve the

intended safety goals:

* Inspect previous repairs made to correct specific engine failures to

ensure that there are no visual or other obvious signs of recurrence. Judgments will have to be made as to the scope, accessibility, and importance of the items in this inspection listing.

* Inspect items recommended by the manufacturer

* Inspect engine liner wear by visual inspection from the crankcase

access ports

* Inspect bearing wear and appearance by selecting two rod bearings for

inspection during each outage

* Perform crankshaft deflection test and alignment for both hot and

cold engine conditions.

2.9
3.0 MONITORING AND TRENDING

Monitoring and trending are treated separately from testing and inspection

in this report; however, all four items are related. Any future use of the

material in this report should also preserve the concept that testing, monitoring, inspection and trending are simply various aspects of an overall process.

To appreciate more fully the benefits of monitoring and trending, one

should be aware of the influence of'maintenance on failure rates. Various

systems, components, machines and other hardware.items respond to major maintenance or replacement in various ways. Airline maintenance research has shown

that most hardware items fit into one of four response patterns (Engineering

News, 1983). Figures 3.1 through 3.4 show the influence of maintenance on the

failure rate response patterns. Each figure caption states the percentage of

components associated with'the specificresponse pattern shown.from the referenced research. During the maintenance period shown in the figures,'equipment

is given a maintenance teardown inspection, components may be replaced and the

unit is reassembled.

Diesel generator systems consist of-thousands of components with many

different functions. The percentages of components-that may fit into each

response pattern have not been'determined-for the diesel gen'erator-system, but

should be-not too far from the experience of;the referenced-research. The U.S.

Navy has shipboard experience which supports the response shown in Figure 3.4

(32% of the components have increased failure rates for periods up to five

years).

When these maintenance response percentages are coupled with the current

nuclear industry diesel generator testing practices the probability of aging

mitigation and reliability improvement is not encouraging. In simplistic

terms, diesel generators are periodically tested until a component fails.

Failed components are maintained or replaced 78% of the time according to the

Phase I results. There may be less than a 20% chance of improving the failure

rate even for a short time, assuming the percentages of Figures 3.1 and 3.2

apply. When this scenario is evaluated, the current regulatory approach

appears weak.

:In view of the generally good reliability results of most diesel'generator

systems'(Nuclear Engineering International 1987), it is obvious that the licensees are doing inspections, monitoring and trending and using good quality

assurance practices. Such practices keep the industry wide results generally

positive. It appeared reasonable to.the diesel experts to recommend that the

regulatory overview be changed to reviewing and monitoring each utility for

their-overall diesel program and thus encouraging the utilities-to review and

modify their inspection, monitoring and trending activities associated with the

diesel generators. Section 5.0 details this recommendation. (Scheible and

McElroy 1987) provides additional'information on trending.

3.1
t

X _.0

c m

= X.

FIGURE 3.1.

0(D

Ca0 -o

0 0

L.' a/

U a) 0 0

Time

Mechanical Failure Pattern 1, Representing only 8% of the Compo- nents Studied. Failure Rate Reduction Due to Maintenance.

FIGURE 3.2.

Time->

Mechanical Failure Pattern

Components Studied. Early

2, Representing 11% of the

Maintenance Benefit Only.

3.2
I*

I -W4sMat

I- .

cn

a, a,MC.. F U . X1

. b .

.

; r

.IFIGURE

--- I .

o . 0 -0

a, a, a,

0.

O 0 a,

C, 0 C.,

a, a,

a, 0 a,

4-' 4-' 4-'

3.3.

Time'

Mechanical Failure Pattern 3, Representing 15% of the

Studied. Maintenance Does-Not-Affect Failure Rate.

Components

I I

a,L \,

ua)

E _

F 3.a,

FIGURE 3.4.

Time -

Mechanical Failure Pattern 4, Representing 66% of the Components

Studied. Maintenance -Increases the'Failure Rate.-

i3.3
3.1 MONTHLY MONITORING

Monthly start-run testing for statistical information (Regulatory Guide

1.108 requirements) with failure reporting and maintenance is a reactive process with no assurance of future operability. A good overall program of testing,, monitoring and trending is a proactive process with a very good assurance

of future operability. Such a program, often called "condition monitoringIt

was recommended by the diesel experts. An overall diesel generator program

should be able to detect many potential failures in incipient states prior to

the actual component failure or loss-of-system function.

For monthly testing and monitoring of the diesel generator system, the

study group offered three recommendations for consideration. The first recommendation is to establish an overall testing and monitoring system that identifies for each specific engine and system the key parameters and indicators

which are precursors to known failure mechanisms or that show degraded performance. The second recommendation is to operate the diesel engine and obtain

specific engine and generator performance information and data. This recommendation had the highest priority of the diesel experts. It generally requires

little or no added instrumentation or equipment. The third recommendation is

to test and monitor the diesel generator instrument and control system to

ensure that the circuits are operable and that key electrical parameters are

not deteriorating. This, circuit diagnostic equipment has not been developed to

a point where it is common practice at the present. time, but it is commercially

available and has been used on other types of electrical systems for this purpose. When using such diagnostic equipment, the diesel-generator system need

not be operating to obtain data and monitor the status of the instrument and

control system. Thus, it adds no known stressors to the aging/ wear concerns

for the system. The instrument and control system has the highest incidence of

failure of all the support systems for the diesel generator system, according

to research results (Hoopingarner et al. 1987).

The study group recommended a monthly testing and monitoring approach for

diesel generators that is significantly different from the approach outlined in

Regulatory Guide 1.108. Testing has been already introduced in Section 2.2 of

this report. The recommended monthly surveillance test and monitoring schedule

is shown in detail in Appendix A. The second monitoring part recommended is a

simple data collection process. However, to be effective, the month-to-month

test variables should be held to a minimum and the data collection and recording process should be well defined by the overall program and supporting

procedures.

The second recommendation for testing and monitoring should follow the

guidelines listed below:

1. The diesel generator should be slow started and loaded, as already

discussed, to avoid the fast-start aging stressor.

2. The diesel unit should then be loaded and run at defined and consistent loads from month-to-month. The test load should be in the

3.4
range of 70 to 90 percent of the engine nameplate rated load which

should correspond to the'plant full emergency load.

3. The recommended diesel run'time is'approximately 12-14 hours, and

should be spread over three shifts. This allows more plant personnel

to be involved and gain familiarity and training with the equipment.

4. The diesel unit should be started about 2 hours before the end of a

work shift. After engine stability is achieved the first set(s) of

data for monitoring the' engine operation-should be 'collected by the

-first shift personnel. 'Another set of monitoring data 'should be'

collected 4-5 hours 'later at a minimum. In actuality, the experts

suggested that'data be collected each hour, with the further recom-'

mendation that the minimum number of data collections-should be three

(one from each shift). The lastidata'set(s) should be 'collected by

the third work shift.

5. Since the data is only collected each month, and some work shifts are

not involved each month, it is important that the data collection

sheets show certain information. The procedures should list any

minimum or maximum values for, each significant parameter. The operators should also be' able to-refer to' past data such as the'last and

average values taken for each-'signific'ant parameter'b'eing monitored. Following this recommendation would reduce'operator'errors,'

add to the'safety of the testing process, and highlight any changes

in equipment performance. '

6. The diesel generator test program may 'include a system startup on

each shift without damage to the engines. This would help in training and general familiarity 'for the station personnel.

7. The routine monitoring'an'd 'trending of. diesel engine base vibration

per se and the diesel start time are'not'recommende'd.- These parameters have normal variations that are too large and other data points

are available which are easier'to interpret and give equivalent

information. 'The vibration, monitoring' of the generator 'gives much

better results'and may be-used for monitoring'. '

8. The data collection, recording,' and'instrument calibration processes

and procedures should follow the station quality assurance requirements for'similar data collection''a'fidfor similar safety functions.

The third recommendation for monitoring consists of a computer run module

that upon command would check 'key electronic'and electrical circuits to''en'sure'

that they appear-to"be in an operational -state. 'Continuity, resistance, function, switching'and other important measurements can be performed very quickly.

A manual ccircuit testing;'proces's is not recommended, it generally is too costly

(labor) for'the'results achieved' and may 'require' job skills 'not available on a

shift schedule. ' ' ' ' ' '

3.5
Automatic or computer run modules for circuit diagnostic testing have been

designed and developed for military and other applications, but have not been

reduced to practice for the diesel generator application. Therefore, the

recommendation is to encourage the development of such specific equipment for

the diesel generator system.

3.2 OTHER PERIODIC MONITORING

Certain aging related parameters and data should be collected on a quarterly basis and during outage'time periods. Fuel oil, lubricating oil, and

cooling water analyses should be made quarterly and carefully monitored so that

aging mitigating measures and actions may be taken. Shaft deflection tests

should be made during the 'refueling outage. The engine should also be carefully monitored for the data listed in Appendix A once'each hour during the

110% load run. The data of interest is chiefly the cooling and lubrication

system performance and cylinder and turbocharger temperatures during this test.

3.3 TRENDING

Without parameter trending, the monitoring recommendations have little

predictive value to the licensees and the NRC. A good trending program is

labor intensive to set up and get running. After that point, for regulatory

Value/Impact considerations, the cost savings in avoided equipment damage and

down time are estimated to have a payback period of less than one year. Thus,

no NRC backfit rule problems are predicted. (Scheible and McElroy 1987) outline additional examples of cost savings experienced.

From the regulatory viewpoint, the generally favorable economic experience

reported makes it easier to get good performance from the licensees. Since it

is in their best economic interest to do a good job of monitoring and trending,

the regulatory controls have to be less prescriptive.

The concept of trending appears simple, but there is an experience

requirement. To predict failure, or the time at which performance is less than

the prescribed performance limit, one has to know both when and how the data

being trended approaches the limit. The limit may be either a maximum or a

minimum (but rarely both) for a single parameter.

For example, a diesel engine bearing is designed for very long life and

bearing temperature is an easy to measure parameter, which changes very slowly

and appears to be a. straight horizontal line. However, at failure the temperature rise is very rapid and may progress from normal to bearing failure' in a

matter of minutes. Thus, the way that bearings fail has to be known (experience) before an end-of-life or a performance'limit can be predicted. Other

bearing condition indicators exist that give much better results. Fortunately,

the experience with diesel engines spans many decades and the trending should

not be too difficult, if experienced personnel are enlisted to help establish

trend limits and the expected failure patterns.

3.6
The variable engine parameters listed in Appendix A should be monitored

and trended. Load and governor settings, for example, are not variables that

need to be trended, but they do need to be uniform from month-to-month.

3.7
4.0 MODIFICATIONS,'TRAINING'AND MAINTENANCE

Certain modifications, training and maintenance requirements must be

addressed to support aging mitigation and the testing described in this report.

The recommendations by the experts' fo-rthes'e requirements are characterized as

"good practice." Many of these rec6mmendations are'already-in place and established as standard practice by'some'utilities,'which-use diesel engines for

base-load service. Nuclear station-practice is also developing better maintenance, training and modification i

mprovements in general agreement-with the

recommendations.

4.1 MODIFICATIONS -

Diesel engine prelube and-keep-warm heating systems have been added

already by the utilities to les'sen the-wear and aging-effects of emergency fast

starts. The study group recommended that-any-engines: that have not been so

modified should have these' modifications added.- Another common modification

being considered and implemented is to move instruments and controls, where

possible, from the engine or engine skid to another off-skid location to

isolate the engine vibrations. This avoids the.aging influence of vibration

which was the chief stressor found in the collective diesel operating experience of the licensees and reported 'in-(Hoopingarner 'et al. 1987).- This modification is' highly'reconimehded. ;

4.1.1 'New Modifications Recommended

'The modifications required to change the monthly testing program from the

present statistical bas'is to meet Regulatory Gu'ide 1.108 requirements to a

monitoring and trending-basis as'recommended by the study group consist primarily of procedural changes with a few local instruments to be added for some

installations. These missing instruments vary among the various engines and

vendors. The vast majority are already installed. Some should be upgraded to

better accuracy, if inadequate for the intended purpose as now 'installed.

Another-modification that-isiow-cost and highly recommended by the study

group is'to 'add manual starting provisions to-the-engines. This will permit

trained operators 'to start an engine'by'going'to-the diesel:generator room-for

recovery from station-blackout.- The modification, in concepti-consists of

levers added to the fuel'control mechanism and some local control provisions

needed to override any instrument and control system components that could

prevent the engine from 'being manually'started. -Manually- operated valves

should be available for'supplying-startup air to the engine. A trained operator would manipulate the'start-air and'fuel-control'levers to start the engine

and bring it to operating speed. This modification would allow a start within

5 minutes. Actually, an experienc'ed operator should be able to manually start

anengine and begin to incrementally load'it in about 1 minute, assuming he is

present at the diesel'and has normal-emergency lights and-related D.C. power.

The other 4'minutes is ass'umed 'to'be needed to pass through security check

points and reach the diesel from other plant areas. Except in the one case of

4.1
a LOCA with a loss of offsite power, this should prevent any core damage and

also RCP seal damage (G.I.-.23 issue). After starting, the engine governor

would control engine speed while the plant electrical loads are energized in

the proper sequence from the plant control room.

A procedure modification and perhaps electrical timers for the auxiliary

lube oil pump (for Fairbanks Morse opposed piston diesels) that would assist in

the lubrication of the upper crankshaft assembly before planned or test starts,

is also recommended. This lube oil pump should be turned on for about 1 to

2 minutes before the engine is planned to start. As an alternative, it may be

possible to increase the existing lube oil standby circulating pump output

pressure several minutes before starting. A similar modification for all

diesel engine types would reduce aging and wear of the intake and exhaust valve

assemblies, which now do not receive standby circulating lubricating oil.

Regulatory guidance and perhaps plant technical specifications will have to be

slightly changed to permit such planned prelube for planned starts. This

should not increase regulatory concerns with unplanned starts without such

prelube conditioning. The reason for no regulatory problems is that there are

no observable effects on the start time or short-term reliability by prelube

practices.

4.1.2 Optional Modifications

Section 3.1 outlined a recommendation to test and monitor the dieselgenerator instrument and control system for function and status. This would

require the addition of circuit diagnostic equipment. The NRC and industry

costs, scope, and other information needed before a final recommendation can be

made have not been completed for such equipment. Therefore, this modification

is only listed for consideration at this time, with the recommendation that the

missing NRC Value/impact level of information be collected as part of the

Phase II research in the diesel generator aging task.

4.2 TRAINING

To avoid maintenance induced aging stressors, PNL recommended that engine

and governor maintenance training needs improvement. Operator training to

overcome failure-to-start and run problems and manual starting of the engines

is'also perceived as a need. Two persons, at a minimum, for each nuclear unit

should-be given maintenance training equivalent to that offered by the'diesel

engine and governorlmanufacturers. Such persons should be at the working

level, and should be used to train and develop the-skills in other maintenance

personnel. Many-utilities already exceed these minimum requirements, but from

time-to-time all licensees need to evaluate the training of new personnel or to

retrain them after certain time periods have passed.

The Phase I Aging Study, Volume I (Hoopingarner et al. 1987) describes the

systems, components and the stressors most likely to be involved in diesel generator aging and failures. Additional training on those items with the higher

failure percentages, such as the instrument and control system and the governor, should give the best results.

4.2
Training in the use of the trending and'monitoring data sheets and procedures will also be required to implement the recommendations in this-report.

The use of failure fault diagrams-with defined corrective actions for

plant operators was also discussed-and recommended. These trouble-shooting

aids list information on the most comm'on causes of failure to start and run

along with the sequence' of correctiveactions. The availability of'such information speeds up the process of starting the engines in a real plant emergency. NRC/NRR may wish to address this issue as part of the review of the

overall diesel generator program plan submitted by the Utilities, as recommended in this report.

4.3 MAINTENANCE

The chief recommendation for maintenance is, in conjunction with an adequate monitoring and trending program, to avoid teardown of the engines simply

for the purpose of inspection. As Figures 3.1 through 3.4 indicate, this may

have an overall adverse influence on the system failure rate. Any significant

components not directly or indirectly monitored would continue with the present

maintenance program. This is not to imply that engine and system components

with a known qualified life would be operated past their qualified time or

operating hour limits, simply because monitoring and trending showed no difficulties. However, such information may be used as a basis for requalifying the

components to a longer time period, as another issue not within the NPAR scope

for further study.

The next recommendation is to ensure that licensee maintenance organizations do not treat the engine governors as "black boxes," which are often left

alone until a failure occurs. The governors must have regular and careful

maintenance, adjustment, and preventative maintenance based on a firm understanding (training) of the governor and its service needs.

Spare fuel pumps, governors and other major components that could be

interchanged to allow maintenance may be attractive to some plant operators and

management. This increases flexibility, choice of onsite and offsite maintenance locations, and ensures that patch-up repairs are not performed simply to

meet the 72-hour technical specification time limits or other operational constraints. The whole area of spare parts needs careful evaluation. With a good

monitoring and trending program some aging related failures can be predicted in

time to order spare parts. Other components with random failure patterns, or

that are not directly monitored and trended, may benefit from additional spare

parts and make it easier to meet the 72-hour rule.

The last maintenance point is that normal engine vibrations have a known

and severe influence on the control system, instrument operation and calibration. Vibration was the diesel generator stressor found to cause the highest

percentage of failures in the PNL research (Hoopingarner et al. 1987). The

obvious recommendation is that engine preventative maintenance should be

increased to mitigate the aging and wear results of this stressor and that any

4.3
monitoring program should have engine or engine skid mounted instrument calibration well under-control for this environmental factor. The point is that,

even with a well running engine, vibration can not be'eliminated, but problems

can be predicted which are caused by vibration. One of these problems is that

monitoring and trending instrumentation may also give erroneous information

because of vibration-induced degradation. The maintenance program needs to

address this issue, and increase such instrumentation calibration and preventative maintenance service.

4.4
5.0 REGULATORY MONITORINGACTIONS RECOMMENDED

The discussion and recommendations inSections 5.0 and 6.0 in this report

are based on the assumption that all previous recommendations are put into

practice by the NRC and the licensees. These two-sections are not intended to

be exhaustive in-their treatment of-these purely regulatory concerns, but only

to document the scope of the discussion in the workshop. Section 5.0 illustrates the concepts of how the NRC overview of diesel generator monitoring and

trending could be accomplished and Section 6.0 addresses the most essential

changes of Regulatory Guide 1.108 to permit such a change in the testing

concept to proceed.

5.1 REGULATORY CONCEPTS

The NRC minimum acceptability of. 95% reliability, or better, is practical

and after some experience in the recommended program, may be increased somewhat.- To assure operational readiness, it is recommended that performance of

the safety'function on plant demand should be the basis for acceptability,

rather than the current test program.. This is essentially the process the NRC

uses for all other plant equipment. A demand is either a test'signal'or an

actual plant event requiring a diesel generator to start and run, regardless of

the overall duration of the-signal or event.

This'report proposes that a new regulatory overview be adopted that consists of an entirely new program for assuring'diesel-generator operational

readiness. As discussed in this report, it consistslof a new requirement that

the licensees should be required to have an approved diesel :generator program

following acceptable guidelines to be developed later. The proposed program

and guidelines outlined in this report is a balanced approach where testing,

inspections, monitoring and trending, training, maintenance and modifications

all have appropriate importance.

It is proposed that the NRC should not track, process or analyze any

diesel generator monitoring and trending data on a routine basis. This would

all be done by the utilities. The NRC should be concerned only with excessive

numbers of failures to respond to valid demands the same as for other major

safety components such as the high pressure safety injection (HPSI) pumps and

motors.

Monitoring and trending of diesel generator operational readiness and performance parameters would be the basis of licensee reports to the NRC rather

than the statistical basis now reported. The NRC overview should not be prescriptive, but rather evaluate the licensee's maintenance, testing, inspection,

monitoring and trending program for diesel generators.

The NRC would evaluate the overall licensee's management and performance

on the diesel generator and give independent reports on performance. This

would place the diesel generator regulatory process in the same conceptual

5.1
process as used for all other significant plant standby safety equipment. The

advantages of the proposed regulatory approach.are:

* The new program is predictive and gives much more assurance of future

engine operability, than current requirements.

* Rather than a-single data point'each month (i.e., a successful or

unsuccessful diesel'start and run), the recommended approach would

give about 150 data points for utility evaluation. Degraded performance would be reported to the NRC for independent evaluation.

* Information on aging, potential common mode failures and other risk

sensitive data would be available to the NRC through the utilities

trending data and the overall diesel program.

* It minimizes the present severe fast-start aging and wear stressor

found in combinations of plant technical specifications, equipment

capabilities and Regulatory Guide 1.108 requirements.

* The proposed program is not costly to implement by either the NRC or

the industry and should increase NRC's confidence in the safety performance of the diesel generator system.

* Due to statistical limitations, rapid and significant performance

degradation may not be detected-for many months by following the

testing requirements of Regulatory Guide 1.108. The proposed testing

and monitoring methods avoid this problem, and significant performance degradation would normally be detected during the next

subsequent engine test period.

5.2
6.0 REGULATORY GUIDES AND STANDARDS

The workshop participants reviewed the Regulatory Guides applicable to the

diesel generators. Only Regulatory Guide 1.108 was significantly involved in

changes required to permit the overall recommended program to proceed as documented in this report. This guide is included as Appendix D and edited to show

the scope of essential recommended deletions and additions.

Technical specifications, and some other nuclear standards such as

IEEE-387 will also be affected. However, such changes were not considered or

documented at the workshop sessions.

6.1
REFERENCES

a. EPRI. 1986a. The Reliability of Emergency Diesel Generators at U.S.

Nuclear Power Plants. EPRI-NSAC-108, Electric Power Research Institute,

Palo Alto, California.

b. EPRI. 1986b. Effect of Diesel Start Time on BWR/6 Peak Cladding

Temperature-Licensing Basis Sensitivity Calculations, EPRI-NSAC-96,

Electric Power Research Institute, Palo Alto, California.

c. PNL. 1985. Review of Resolution of Known Problems in Engine Components

for Transamerica DeLaval Inc. Emergency Diesel Generators. PNL-5600.

Pacific Northwest Laboratory, Richland, Washington.

d. Hoopingarner, K. R. J. W. Vause, D. A. Dingee and J. F. Nesbitt. August

1987. Aging of Nuclear Station Diesel Generators: Evaluation of

Operating and Expert Experience. Phase I Study, Volume 1, NUREG/CR-4590,

PNL-5832, prepared by Pacific Northwest Laboratory for the U.S. Nuclear

Regulatory Commission, Washington, D.C.

e. Hoopingarner, K. R. and J. W. Vause. August 1987. Aging of Nuclear

Station Diesel Generators: Evaluation of Operating and Expert

Experience. Workshop, Volume II, NUREG/CR-4590. PNL-5832, prepared by

Pacific Northwest Laboratory for the U.S. Nuclear Regulatory Commission,

Washington, D.C.

f. Engineering News, June 17, 1983. (international edition).

g. Nuclear Engineering International, 1987. "EPRI Finds The Reliability of

U.S. Diesel Generators is Excellent" May 1987, pp. 54-55.

h. Scheibel, J. R. and J. McElroy. 1987. "On-Line Diagnostic Monitoring For

Life Extension." American Power Conference, Chicago, Illinois, April

1987.

R.1
APPENDIX A

RECOMMENDED DIESEL GENERATOR MONTHLY TEST PARAMETERS
APPENDIX A

RECOMMENDED DIESEL GENERATOR MONTHLY TEST PARAMETERS

This appendix gives a suggested list of monthly test parameters that

should be monitored to trend the diesel generators for. assurance of future

operability. The listed parameters are generic by necessity due to the existence of many engine manufactures and model types. The recommended testing is

an extension of that required by standard IEEE-749.

Fuel consumption tests at each refueling outage, load acceleration tests

and similar specific tests are not listed in this appendix.' Appendix A is

intended only for periodic monthly testing to determine the presence or absence

of indicators of engine operability. Special tests''may warrant the assistance

of diesel generator experts, or specialists, generally not available on the

plant technical staff.

All monthly test programs should be documented, should follow a written

checklist and should be signed off according to the plant quality assurance

program.

A.1
Parameter Requirements

General Data Required Optional

Date of test X

Time of test X

Total hours on engine (hour meter) X

Starting air pressure X

Engine speed or electrical frequency X

Generator Data (Alternator)(a)

kW X

Volts X

Kilovars x

Alternator winding temperature X

Alternator bearing temperature (One or two X

bearings) (Oil temperature) amps per phase X

Engine Cooling Water

Water pressure to engine X

Water temperature to and from engine X

Water pressure to and from engine water X

cooler

Water temperature to and from engine water X

cooler (could be radiator)

Water pressure to and from raw water cooler(b) x

Water temperature to and from raw water cooler(b) x

Water pressure to and from turbocharger X

Water temperature to and from turbocharger X

Water pressure to and from turbocharger after(b) x

cooler

Water temperature to and from turbocharger X

after cooler

Water pressure and temperature to and from L.O. X

cooler

Jacket water pump pressure (to and from) X

Lubricating Oil

Oil pressure to engine X

Oil temperature to and from engine (oil sump X

temperature)

Oil pressure to and from L.O. filter X

Oil temperature to and from L.O. cooler X

Oil pressure to and from L.O. cooler X

A.2
Parameter Requirements -General Data Required Optional

Lubricating Oil (contd)

Oil pressure to turbocharger X

Oil temperature to and from turbocharger X

Air to Engine

Ambient air temperature X

Barometric pressure X

Relative humidity : b X

Air pressure to turbocharger(b) X

Air temperature to turbocharger X

Air temperature to and from after cooler X

Air pressure to and from after cooler X

Exhaust

Exhaust temperature out of each cylinder X

Cylinder No. 1

Cylinder No. 2

Etc.

Exhaust temperature to turbocharger turbine X

(preturbine temperature), more than one

thermocouple may be requi

Exhaust pressure to turbineF61 X

Exhaust temperature from turbine X

Exhaust back pressure in exhaust pipe after X

turbine exhaust expansion section

Fuel Oil

Fuel oil pressure to and from pre-day tank filter(b) X

Fuel oil pressure to and from engine filter X

Fuel oil pressure to and from fuel oil pump X

Fuel oil temperature to engine X

Fuel Pump Rack Setting

All cylinders X

Miscellaneous Data

Turbocharger R.P.M. X

Lube oil level in engine sump X

Water level in expansion tank X

Crankcase vacuum or pressure X

Crankcase blow-by, measure pressure drop across X

blow-by orifice (could use gas analysis

technique)

Amount of oil added X
Parameter Requirements

General Data Required Optional

Miscellaneous Data (contd)

Exhaust smoke color or smoke meter reading X

Lubricating oil analysis (quarterly recommended) X

Engine cooling water analysis (quarterly recommended) X

Fuel oil analysis (upon delivery recommended) X

Number of engine starts to date X

(a) Note it is important that the same electrical load be used for each test

(e.g., 100% of plant load).

(b) Where equipment exists.

A.4
APPENDIX B

RESUMES

Resumes of the two consultants used by-PNL for the diesel generator - research and who participated in the discussions reported in this document are

presented in this appendix.

. . . . .. . .

... .. ,-- , . :

. ,, ; .

..

. . . . .

. . . . , r

J . . . : .

B.1
B. J. KIRKWOOD, P.E.

Covenant Engineering

P.O. Box 788 Buena Vista, CO 81211

(719)395-6056

Registered Professional Engineer - CO, MO, KS, NE, IA (inactive)

Massachusetts Institute of Technology - 1950 - BS/Mechanical Engineering

- 1950 - MS/Econ & Engrg.

Member: American Society of Mechanical Engineers

Associate - Internal Combustion Engine Div. (+ 2 others)

Secretary (1967-73) Performance Test Code Com. #17,

Reciprocating Internal Combustion Engines

American Solar Energy Society

National Society of Professional Engineers

Colorado Engineering Society (ex - MoSPE and KsES)

Pi Tau Sigma (national honorary ME fraternity)

1984 - present -

1982 - 1984 -

Covenant Engineering - Self-employed consulting engineer

(semi-retired)

Services include studies and consultation on: power supply

planning; utility rates and economics; diesel engine applications; project administration and financing; utility

coordination; and nuclear EDG applications and consultation

on related regulatory concerns.

B. J. Kirkwood, PE,

Village, KS 66208)

retired)

Consulting Engineer (4308 W 79th Prairie

- Self-employed consulting engineer (semi1954 - 1982 - A.

MO

C. Kirkwood and Assocs. (8080 Ward Parkway, Kansas City,

64114)

(A consulting engineering firm with a staff of generally

35-40, doing municipal, industrial and other governmental

work in the fields of power, water, sewage, gas rates,

feasibility studies, energy analyses, etc.)

Retired 1/1/82 as one of the three senior partners.

Responsible for quality assurance and procedure for all

specifications, studies and reports; directed all and

performed many economic and rate studies; project sponsor

for majority of engine-generator project designs; director

of long-range planning and business analyses for Firm.

Until 1977 was Director of Administration, Participated in

Client Relations, Business Development and various

professional and technical matters.

B.2
NB: ACK&A-was responsible (1947-1982) for probably

more engine-generator installation designs than any

other firm in thermid-states (the heart of smaller

municipal and REC utilities), embracing at least 13

basic models'of seven engine manufacturers, ranging in

size from' 600 to 700 kW, and speeds of 200 to

900 rpm. .BJK was responsible for 15 diesel projects

for 10 different-clients involving 19 engines of 5

different makes. Also directed study of present and

future engine utilization for the Electric Power

Research Institute.-

- R. R. Donnelley I& Sons (Chicago) printers - industrial

engineer; purchasing agent.

- Several articles for'Diesel-and Gas-Turbine Progress

magazine; papers and presentations for Energy Technology

Conference, Diesel' Engine'Manufacturers Association, Kansas

Municipal Utilities, and Iowa Association of Municipal

Utilities.

1950 - 1954

Publications,

ect.

I. " F

- B.3
PAUL J. LOUZECKY, PE

Engineered Applications Corp

476 Sarsfield Drive

Rochester Hills, MI 18063

(313)853-3992

EXPERIENCE

June 1975 to present President of Engineered Applications Corporation, very

active consulting service specializing in diesel

engines, combustion engines, and related analytical

services. Typical services include torsional and

vibrational analysis using, computer' modeling, maintenance and operational problem resolution and consulting,

consultant and expert witness services for the U.S.

government, National Laboratories, and other engineering and private business firms. A major business

area has been Nuclear Service Diesel Generator installations and related maintenance and performance

consulting services.

JUNE 1970--DETROIT DIESEL ENGINE DIVISION, GENERAL MOTORS CORPORATION,

JUNE 1975 DETROIT, MICHIGAN

May 1974-May 1975

Feb. 1974-May 1974

Mar. 1973-Feb. 1974

Jan. 1971-Mar. 1973

Worked on the design and development of an 8-cylinder,

vee, 4-cycle diesel truck engine, both naturally aspirated and turbocharged. Did much of the analytical and

vibration design work on this engine.

Designed a high-pressure, high-speed fuel injection

pump for use on a rotary combustion diesel engine.

Each pump plunger was designed to deliver fuel 4000

times per minute.

On loan to the Engineering Staff of General Motors

Corporation to design and develop a stratified-charge

automotive gasoline engine. The engine had better

specific fuel consumption and lower emissions than the

Honda CVCC engine.

Supervisor in charge of the engineering and design of

three rotary combustion diesel engines. Also assisted

on the design and development of the rotary combustion

gasoline engine.

Jun. 1970-Jan. 1971 Executive Engineer on the MBT-70 Main Battle Tank Program reporting to the Chief Engineer. My work consisted of solving a number of vehicle-related problems,

such as correcting the large number of engine (power

B.4
plant) problems including cylinder block cracking,

piston scuffing,-engine and power plant torsional

vibrations.'

JULY 1963--RESEARCH LABORATORIES, GENERAL MOTORS CORPORATION,

JULY 1970 WARREN, MICHIGAN

Supervisory Research Engineer in the Mechanical

Research and Special Projects Departments. In .this

capacity; I conducted work on a number of interesting

projects' which included: new, very compact locomotive

engines, thermal energy storage automobile with

Stirling engine (emissions free), thermal energy

storage submarine engine (Stirling engine), continuous

casting machine for casting many metals including

steel, transportation studies, very high speed

transportation systems, and'fuel injection studies.

JUNE 1963--WAUKESHA BEARING COMPANY, WAUKESHA, WISCONSIN

JULY 1963

Consulting Engineer; made a market study on the

potential market for internal combustion engine

bearings.

MAY 1958--NORDBERG MANUFACTURING COMPANY, MILWAUKEE, WISCONSIN

JUNE 1963

Chief Engineer, Engineering, Installation and Service

Departments of the Engine Division. In charge of the

engineering and the administrative operation of these

departments, which included-all design, research,

development and testing of new engines as well as

' improving all production two-cycle and four-cycle

diesel, DUAFUEL, TRIFUEL, spark-ignition, and propane

engines, both naturally aspirated and turbocharged.

The work also included all installation, service and

customer contact work related to these

responsibilities. Supervised about 250 people.

APRIL 1935--CLEVELAND DIESEL ENGINE DIVISION, GENERAL MOTORS

MAY'1958 CORPORATION, CLEVELAND,bOHIO

1955-1958 Chief Technical Engineer in Charge of Analytical

Design,'Vibration, Instrumentation, Engineering Welding

Design, Metallurgy, Chemical Laboratory, Instruction

Books, and Research and development Sections. supervised about 100 people.

.4B.5
1951-1955 Head of Analytical Design Section and Special Problems

Section. Worked on the design of over fifty different

types of internal combustion engines.

1947-1951 Supervisor of Special Problems Section. One interesting problem was the design and development of a submarine engine to run under water with a closed-loop

intake and exhaust system.

1937-1947 Head of Analytical Design Section. Responsible for all

stress analysis work on engine design, vibrations,

governing, engine performance and electrical power

plant systems.

1935-1937 Assistant in Analytical Design Section, in charge of

all engine stress analysis and related work regarding

the designing and development of all types of internal

combustion engines and related power plant installation

problems.

JAN. 1934--WEATHERHEAD

APRIL 1935

COMPANY, CLEVELAND, OHIO

Assistant in Research Laboratory: developed new

hydraulic equipment, very high pressure flexible hose,

and automotive and aircraft fittings; hydraulic and

related automotive hardware and accessories. Also

developed the copper brazing technology.

JULY 1933--ELECTRIC PRODUCTS COMPANY, CLEVELAND, OHIO

JAN. 1934

Assistant Chief Draftsman: designed and developed a

considerable number of specialized electrical generators, platers, welders, switchboards, motors, and other

electrical machinery.

EDUCATION

1933 M.S. Mechanical Engineering, Case Western Reserve University, Cleveland,

Ohio. Graduate Thesis: "Dynamic Flow Characteristics of Molten

Lead.

1932 B.S. Mechanical Engineering, Case Western Reserve University

B.6
PROFESSIONAL AND TECHNICAL SOCIETY MEMBERSHIP

Registered Professional Engineer, State of Ohio (E-003068); American Society of

Mechanical Engineers; Society of Automotive Engineers; Sigma Xi Honorary

Science Fraternity.

TECHNICAL SOCIETY PAPERS

"Burning of Heavy Fuel in a Medium Speed, High B.M.E.P. Engine," American

Society of Mechanical Engineers Paper No. 63-OGP-13, presented at O.G.P.

Meeting in St. Louis, Missouri, May 19-23, 1963.

"Vibrations in River Towboats," Society of Automotive Engineers, Paper No.

699A, presented at Marine Propulsion Meeting, May 14-15, 1963, St. Louis,

Missouri.

"Design and Development of a Two-Cycle Turbocharged Diesel Engine," American

Society of Mechanical Engineers Paper No. 56-A-100, presented at the ASME

Annual Meeting, New York, N.Y., November 25-30, 1956. Received award for Best

ASME-OGP Paper presented in 1956.

PATENTS

U.S. Patent No. 2,728,331, "Engine Lubrication and Piston Cooling,"

December 27, 1955.

U.S. Patent No. 3,177,997, "Electric Clutch and Automatic Starting for

Engines," April 15, 1965.

U.S. Patent No. 3,800,179, "Self-Cleaning Spark Plug," March 26, 1974.

U.S. Patent No. 3,861,837, "Liquid Cooled Rotor Housing," January 21, 1975.

U.S. Patent No. 3,877,852, "Rotary Engine Drain Pump Arrangement," April 15,

1975.

March 1974, Pending: "Rotary Machine Apex Seal."

May 1974, Pending: "Split Phasing Gear for a Multi Rotor, Rotary Combustion

Engine."

September 1974, Pending: "Rotary Combustion Engine Damped Apex Seal."

B.7
APPENDIX C

WORKSHOP AGENDA
April 16, 1987

Page 1

WORKSHOP AGENDA

DIESEL GENERATOR AGING MITIGATION

Buena Vista, Colorado

April 29-30, 1987

Sumac Lodge

GOAL

To develop a fresh approach and a broad scope of all

will have a good potential to mitigate aging affects

diesel generators.

possible activities that

and effects related to the

Wednesday

8:00 am

8:20 am

9:45 am

Outline of goals, ground rules, agenda and the contractor deliverable reports.

Review of NUREG/CR-4590 document and the stressors identified and

the problem areas. Expand the detailed workshop topical items

written by K. Hoopingarner to ensure a complete scope is outlined

for further discussion.

Break.

10:00 am

12:00 pm

1:00 pm

3:00 pm

Discussion of Inspection and Testing items on

relation to mitigation and regulatory needs.

reliability focus, also where required.

the topical list in

Availability and

Lunch.

Discussion of Monitoring and Trending items on the topical list

in relation to mitigation and regulatory needs. Availability and

reliability focus, also.

Break.

3:15 pm

5:00 pm

Discussion of Modifications, Maintenance, Training and related

items to mitigate aging.

Adjourn.

.C.1
I

April 16, 1987

Page 2

Thursday

8:00 am

10:00 am

10:15 am

12:00 pm

Discussion of Regulatory Guide 1.108 items and document proposed

changes to match aging mitigation requirements for NRC research

consideration.

Break.

Areas of future research needs, utility cooperation, and implementation needs for diesel-generator aging mitigation. If time

permits, we will discuss diesel life extension.

Lunch.

1:00 pm Document workshop and

ready for reporting.

contractors and PNL.

ensure that all notes are complete and

Assign any follow up items to the

C.2
APPENDIX D

U.S. NUCLEAR REGULATORY COMMISSION, REGULATORY GUIDE 1.108
U.S. NUCLEAR REGULATORY COMMISSION

Revision 1

August 1977

REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.108

PERIODIC TESTING OF DIESEL GENERATOR UNITS

USED AS ONSITE ELECTRIC POWER SYSTEMS

AT NUCLEAR POWER PLANTS

' - _ . - r 

A. INTRODUCTION

Criterion XI: "Test Control." ot Appcndix B,

'Quality Assurance Criteria for Nuclear Power

Plants and Fuel Reprocessing Plants:' to 10 CFR

Part SO, "Licensing of Production and Utilization

Facilities," requires that a test program be es-.

tablished to ensure that systems and components per.

form satisfactorily and that the test program include

operational tests during nuclear power plant operation.

Criterion 17, "Electric Power Systems." of Appen- dix X. "General Design Criteria for Nuclear Power

Plants." to 10 CFR Part SO requires that onsite

electric power systems have sufficient independence,

capacity redundancy, and testability to perform their

safety functions. assuming a single failure. -

Criterion IS, "Inspection and Testing of Electric

Power Systems'" of Appendix A to 10 CFR Part 50

requires that electric power systems important to

safety be designed to permit appropriate periodic inspection and testing to assess the continuity Of the*

systems and the condition of their components.

This regulatory guide describes a method acceptable to the NRC staff for complying with the Com.

mission's regulations with regard to periodic testing

ot diesel electric power units to ensure that the diesel

electric power systems will meet their availability requirements. The Advisory Committee on.-Reactor

Safeguards has been consulted concerning this guide

and has concurred in the regulatory position .- -

features if a loss of offsite power and an accident occur during the same time period and (2) to provide

power to equipment needed to maintain the plant in a

sate condition it an extended loss of otfsite power oc.

curs. Diesel generator units are the most common

source Of onsite electric power.

High reliability must be designed into the diesel

generator units and maintained throughout their service lifetime by appropriate testing, maintenance, and

operating' programs. Branch Technical Position

EICSB 2, "Diesel-Generator Reliability Qualification Testing." dated 11/24/75, of the Standard

Review Plan (Appendix 7-At fNUREG-7S/087') establishes a reliability goal of 0.99 (at a nominal 50'

confidence level) and an acceptable qualification

testing program for diesel generator units of a type or

size not previously used as standby emergency power

sources in nuclear power plants. The preoperational

and periodic testing provisions set forth in this guide

have been designed to provide a basis for taking those

corrective actions needed to maintain high inservice

-rliability of installed diesel generator units. In addition, the data developed will provide an ongoing

demonstration of performance and reliability for all

diesel generator units after installation and in service.

Reliability objectives concerning the entire onsite

electric power system's probability of failure depend

on the interconnections among the system's components and are not within the scope of this guide. "Failure" is taken here to mean the failure to start

accelerate. and assume the design-rated load within

,and for the time prescribed during an emergency or a

valid tesLt

The purposes Or onsite electric power systems are

(I) to provide power promptly to engineered safety

Lifns indicate subtiantive ihanges from previous issue.

' -I NURE- 5/07. Standard Review Plan for the Review of

Safety Analystis Reports for Nudcar Power Plants. U.S. Nuclear

Regulatory Commission. Copies may be purchased from the

National Technical Information Service. Springfield. Virginia 22 1 61. - -X,- - I ~ .' ' , .

USNRC REGULATORY GUIDES C.-e'e kma beW -,. tt see,... a' oft ca-.,.e us. la.. A.~ Ray. W ~ ~ v a in~ C .a'e m w~ w ~ e a~e a~a~~ m a m a .' CA .. . IN D C 2os ss . A llo- - : .~ a ., . fep.a" W ,.a C - .. .e . . e " a t a E0 be0 a m .44w , .m ,be W q evi ... ~ Tm",, , a e .. a e I ' .a N m ~ a. mm a '.. M . .taas C 4 a.0 " 5e a .1 9 . m ,. a., S t P. a aw , C ..

S a W, w a~, m e. .. 4 1. .. *.m e .* ..., aa' oa If, V -im w be a... . .W Re ae~e" a. 2.. RA. - f ,1.tm a ..

-m ,., ~ m S W e y m e g .m a a .q ., a m .. * , m e m ~ e e . w . 2 1 .,: N W sa * ,a 4.e ,A. O ...Vo a -. . y a' I W W kwem S. e Cm., * ~. 1..-a.'a'am~aemgla. AaauI

. a1 0 W S01 , -el 1e ft-. s. "WOW -,., IllWoo- e ee .O

is rmeam.. a .- , e-P -ma 16 Wooa .. e .. Wm~ ,as S ...Of .

ma, - a- 4,W qN m VWe. V. W I.*. C ~ - 5.4.. "Sf - ma.p

41 a.,. W... le~ -., - e.." s Im U S. hma R 1..a W Co .... .a

D.1
I

The testing of the diesel generator unit should

simulate. where practicable. the parameters of opera.

tion (automatic start, load sequencing, load shed.

ding, operation time. etc.) and environments

(temperature, humidity. etc.) that would be expected

if actual demand were to be placed on the system.

This guide provides design and operational provi. sions for the performance of periodic testing of diesel

generator units used for onsite electric power for

nuclear power plants. A "diesel generator unit" con.

sists of the engine. generator. combustion air system.

cooling water system up to the supply, fuel supply

system, lubricating oil system, starting energy

sources. autostart controls, manual controls, and

diesel generator breaker.

C. REGULATORY POSITION

I. General

a. The design of a diesel generator unit should be

such that it can accommodate diesel generator testing

as defined in Regulatory Position C.2.

b. Diesel generator units should be designed to be

testable during operation of the nuclear power plant,

as well as while the plant is shut down. The design

should include provisions so that the testing of the

units will simulate the parameters of operation

(outlined in Regulatory Position C.2) that would be

expected if actual demand were to be placed on the

system.

(I) Capability should be provided to test each

diesel generator unit independently of redundant units. Test equipment should not cause a loss of independence between redundant diesel generator units

or between diesel generator load groups.

(2) Testability should be considered in the selection and location of instrumentation sensors and

critical components (eg.. governor. starting system components). Instrumentation sensors should be

readily accessible and designed so that their inspec- tion and calibration can be verified in place.

Testability should be considered in selecting critical

components. and the overall design should include

status indication and alArm features.

also be provided between diesel generator unit testing

locations and the main control room to ensure that

the operators are cognizant of the status of the unit

under test.

(5) The surveillance system should indicate

which of the diesel generator protective trips is ac.

tivated first in order to facilitate trouble diagnosis.

(6) All diesel generator protective trips should

be in force during diesel generator unit testing.

c. Detailed step-by-step procedures should be

provided for each test under Retulatory Position C.2.

The procedures should identify those special arrange.

ments or changes in normal system configuration

that must be made to put the diesel generator unit under test. Jumpers and other nonstandard configura- tions or arrangements should not be used subsequent

to initial equipment startup testing.

d. Subsequent to any failure the cause should be

determined and corrective action taken in a timelv

manner, with emphasis on preventing reoccurrence of

the failure.

2. Testing

a. Testine of diesel eenerator units durinz the olant 13reooer21ionAL.1n~ = ;ndatlest2

every 18-months should:

(1) Demonstrate proper startup operation by simulating loss of all a.c. voltage and demonstrate

that the diesel generator unit can start automatically

and attain the required voltage and frequency within

acceptable limits and time. -

(2) Demonstrate proper operation for design.

accident-loading-sequence to design-load require.

ments and verify that voltage and frequency are

maintained within required limits.

(3) rDemonstrate full-load crrinit canabilitv

for an nic lf not eets than 14 hours nfwhich "I

hours -thm.ld he it a load euivalent to the can

tirnouqsrain2aoftLhe diWzLverator and hpurs d at a

load eouivalent to the auati t diesel.

_enerator. Verify that voltage and frequency requirements are maintained. The test should also verify that

the cooling system functions within design limits.

(4) Demonstrate proper operation during diesel

generator load shedding. including a test of the loss

of the largest single load and ofcompiete loss of load,

and verify that the voltage requirements are met and

that the overspeed limits are not exceeded.

(5) Demonstrate functional capability at full.

load temperature conditions by. rerunning the test

phase outlined in Regulatory Positions C.2.a.(l) and

(2) above immediately following (3) above.

.,

I

I

I o t

I (3) Periodic testing of diesel generator units

should not impair the capability of the unit to supply

emergency power within the required time. Where

necessary, diesel generator unit design should include

an emergency override of tite test mode to permit

response to bona fide signals.

(4) A surveillance system should be provided with remote indication in the control room as to

diesel generator unit status. i.e.. under test, ready- standby, lockout. A means of communication should

'l-.4- Load1

'OK) 3* rt

IL% +44js +es-t

1.108-2

D.2
1L4.+tri.- .... (6) Demonstrate the ability to (a) synchronize the diesel generator unit with offsite power-while the

unit is connected to the emergency load. (b) transfer

this load to the offsite power. (e) isolatc the diesel

generator unit. and (d) restore it to standby status.

(7) Demonstrate that the cngine will perform

properly if switching from one fuel oil supply system

to another is a part or the normal operating

procedure to satisfy the 7-day storage requirement.

C.2.a.(9), the interval- for periodic testine under

Regulatorv Position C.2.c (on a per diesel generator

O) bitt

L:'.1 r1'o

umt basis) should be no more than 31 davs and

should depend on demonstrated oenrfOrMapce If

more than one failure has occurred in the last 100 - tests (on a per nuclear unit basis). the test interval

should be shortened in accordance with the following

schedule.:

(I) If the number of failures in the last 100 valid

tests is one or zero. the test interval should be not

more than 31 .days.

(2) If the number of failures in the last 100 valid

tests is two, the test interval should be not more than

14 days.

W

'I

liiv (8) Demonitrate that the capability of the diesel

RE.sio'd ~generator unit to supply emergency power within the

* required time is not impaired during periodic testing ~. *b^1J.I under Regulatory Position C.2.c.

L. G I- e (9) Pemonstrate the required reliability bv

A of any 69 consecutive valid tests' (per plant)

nopucrdt with no failures, with a minimum of 23 or 69/n tests,

:4 Vno k whichever is the larrer. per diesel generator unit

5+A~ft (where n is equal to the number of diesel generator

% units or the same design andize}. s I

b. Testing or redundant diesel generator units

during normal plant operation should be performed

independently (nonconcurrently) to minimize common failure modes resulting from-undeteted interdependences among diesel generator units. oi However, during reliability demonstration of diesel

generator units during plant preoperational testinrg and testing subsequent to any plant modification

where diesel generator unit interdependence may

have been affected or every 10 years (during a plant

shutdown). whichever is the shorter, a test should be

conducted in which redundant units are started

simultaneously to help identify certain ,common

failure modes undetected in single diesel generator

unit tests.

c. Periodictestineofdiesel eneratorunits durin

,gormaT pi-ant overationsho~uldL_

(1) Demonstrate proper startup and verify that

0 °t i the required voltage and frequency are automatically attained within acceptable limits and time. This test

should also verify that the components of the diesel

4V LC :generator unit required for automatic startup are

teIoccA OP~t X ; ,-C Aio-7ss

(2) ernonstrate full-loadbi r'ryng =pziuly. OL ( continuous ratintl for an interval of not less ham

C L one hour. The test should also verify that the cooling

Sy64u.adsytem functions within design limits. This test could

/ t Isr,)be accomplished by synchronizing the generator with

I the offsite power and assuming a load at the awP

Of '~~~1 4isle.'eo

d. After completion of the diesel generator unit

I reliability demonstration under Regulatory Postition

1 Valid test as defined in Regulatory Position C.'c.

iSLO.-

aeAo&No +4%q4

.~tv .

9e~w tu-ecA*'

MC (3) If the number of failurEs ti the last 100 valid

tests is three, the test interval should be not more

than 7 days.

(4) If the number of failures in the last 100 valid

tests is four or more, the test interval should be not

more than 3 days.

e. -Valid tests and 'failures (under Rcguiaiory

-Positions C.2.a.(9) and C.2.d) should be based on the

following criteria:

(1) All start attempts (automatic, including

those from bona ride signals, or manual) that result in

a failure to start. except as noted in (2) below, should

be considered valid tests and failures.

(2) Unsuccessful start and load attempts that

can definitely be attributed .to operating error, to

spurious operation of a trip that is bypassed in the

emergency operating mode. to malfunction of cquipment that is not operative in the emergency operating

mode (e.g., synchronizing circuitry) or is not pan of

the defined diesel generator unit design should not be

considered valid tests or failures.

(3) Successful stiats. including those initiated by bona ride signals, followed by successful loading (se- quential or manual) to at least 50% of continuous I

rating and continued operation for at least one hour - should be considered valid successful tests.'

(4) Successful starts that are terminated inten.

tionally without loading, as defined in (3) above,

should not be considered valid tests or failures.

Ve'ThfsA

(5) Successful starts followed by an unsuccessful

loading attempt should be considered valid tests and

failures, except as noted in (2) above.

(6) Tests that are terminated intentionally oDy u4- PDav)a before completion as defined in (3) above because ofr

an alarmed abnormal condition that would ultimate. N'eMdS 46 (e.

ly have resulted in diesel generator damage or failure de1 a i. -. ,e should be considered valid tests and failures. G Wl j ;

erg cc~e-cty eG

1.108 .3 C"Xire~sboS~ ae,(Jbl X

-14 t e I . .

,

Li -4 lvIz. d-+. ±+, a 4Ak 2 4~64- pel,. T-p t G~al J'e(~a 4

D.3
(7) Tests performed in the process of

troubleshooting should not be considered valid tests.

or, Tests that are performed to verify correction of tie

problem should be considered valid tests and successes or failures. as ancrooriate.

generator units requires special evaluation, and the

information provided on the report form should be

supplemented, as needed. by additional narrative

material that:

(1) Identifies the reported failure as the 7th or

(8) Cranking and venting procedures that lead greater failure in the last 100 valid tests,

01<- ,b- i. to the discovery of conditions (e.g., excessive water or

bib 4, oil in a cylinder) that would have resulted in the (2) Describes corrective measures, taken or

failure of the diesel generator unit during test or dur- planned, to increase the reliability of the generator

O ttLoQ.A- ing response to a bona fide signal should be can- units,

+Ci'S. bizsidered a valid test and failure.

.; vL-!~sidcrd a valid test and failure. ,(3) Provides an assessment of the existing

3. Records and Reports see- 2p. bela4" reliability of electric power to engineered-safety- _2eature equipment.

a. All start attempts. including those from bona

.fidejgalz.lqjL4 be oggd., The log should (4) Provides the licensee's basis for continued

describe each occurrence in sufficient detail to permit plant operation if that is planned, and

independent determination of statistical validity in -

accordance with Regulatory Position C.2.e. (5) Provides a summary of all tests (valid and inMaintenance, repair, and out-or-scrvice-time valid) that occurred within the time period over

histories, as well as cumulative maintenance and which the last 100 valid tests were performed. and

operating data, should also be logged. Cumulative verifies that surveillance testing during this period

statistical analyses of diesel generator unit test was in conformance with the schedule of Regulatory

results, together with results of operation of the diesel Position C.2-d.

generator unit when required by actual demand.

should be maintained. These analyses should include Invalid failures experienced during trouble.

examination of the trend of critical failure shooting should be included in the report of the

mechanisms. human errors, and common mode failure (valid or invalid) that made the

failures. troubleshooting necessary.

b. All diesel generator, unit failures, valid or invalid, should be reported'" consistent with the

licensee's reporting requirements. This report should

(I) identify the diesel generator unit involved, (2)

identify the failure as being the nth failure in the last

100 valid tests, (3) describe the cause of failure. (4) describe the corrective measures taken, (5) indicate

the length of time the diesel generator unit was unavailable. (6) define the current surveillance test interval, and (7) verify that the test interval is in conformance with the schedule or, Regulatory Position

C.2-d. If the number of failures in the last 100 valid

tests is seven or more. tne reliability of the diesel

I See ReguLtuory Guide 1.16. 'Reporing or Operating Informaion. -

D. IMPLEMENTATION

The purpose of this section is to provide information to applicants regarding the NRC staffs plans for

using this regulatory guide.

This guide reflects current NRC staff practice.

Therefore, except in those cases in which the applicant proposes an acceptable alternative method for

complying with the specified portions of the Commission's regulations. the method described herein is be.

ing and will continue to be used in the evaluation of

submittals for construction permit applications until

this guide is revised as a result of suggestions from the

public or additional staff review.

VAO+,e Z.,

Tt, c ~k0~.JA 4~. L~e/.~okS,4,L _45LpJ-~ -is e.eco&.4,v e-,a114 L08

1.108-4

D.4
PNL-6287

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