Regulatory Guide 1.9

Selection, Design, and Qualification of Diesel-Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants

ML13350A381
Person / Time
Issue date:	11/30/1978
From:	NRC/OSD
To:
References
RG-1.009, Rev. 1
Download: ML13350A381 (3)

Revision 1 U.S. NUCLEAR REGULATORY COMMISSION November 1978 k REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.9 SELECTION, DESIGN, AND QUALIFICATION OF DIESEL-GENERATOR

UNITS USED AS ONSITE ELECTRIC POWER SYSTEMS

AT NUCLEAR POWER PLANTS

B. DISCUSSION

General Design Criterion 17, "Electric Power A diesel-generator unit selected for use in an Systems," of Appendix A, "General Design onsite electric power system should have the Criteria for Nuclear Power Plants," to 10 CFR capability to (1) start and acceate a number Part 50, "Domestic Licensing of Production and of large motor loads in rapid ar sion and be Utilization Facilities," includes a requirement able to sustain the loss ok an o%1._y part of such loads and maintain v0I*ge an, Irequency that the onsite electric power system have sufficient capacity and capability to ensure within acceptable limit " supply power that (1) specified acceptable fuel design limits continuously to the i V~eded bq*"4 to main- and design conditions of the reactor coolant tain the plant in a .*2e c 4itioA if an extended pressure boundary are not exceeded as a loss of offsite po A~r o urý b'

result of anticipated operational occurrences A

• and (2) the core is cooled and containment in- IEEE Std -197 ;,,; E Standard Criteria tegrity and other vital functions are maintained for Diesel-G * k*tor mits Applied as Standby in the event of postulated accidents. Power " K Nuclear Power Generating Stations 4ceea'kes principal design criteria Criterion III, "Design Control," of Appen- an ,}*ua a testing requirements that, if dix B, "Quality Assurance Criteria for Nuclear foI , help ensure that selected diesel- Power Plants and Fuel Reprocessing Plants," to .genrhrat" Units meet their performance and

10 CFR Part 50 includes a requirement that ' a h*t'requirements. IEEE Std 387-1977 was measures be provided for verifying or checking 'f; ed by Working Group 4.2C of the the adequacy of design by design reviews, J%$. cl r Power Engineering Committee (NPEC)

the use of alternative or simplified calculati al ot0 .he Institute of Electrical and Electronics methods, or by the performance of a suit".e Engineers, Inc. (IEEE), approved by NPEC,

testing program. , and subsequently approved by the -IEEE Stan-

- " dards Board on September 9, 1976. IEEE Std Diesel-generator units have been wiely ud 387-1977 is supplementary to IEEE Std 308- as the power source for the onsiV le ic 1974, "IEEE Standard. Criteria for Class IE

power systems. This regulatory gfiae - Power Systems and Nuclear Power Generating scribes a method acceptable to the NRC staff Stations,"' and specifically amplifies paragraph for complying with the a mission's require- 5.2.4, "Standby Power Supplies," of that doc- ments that diesel-gene units intended for ument with respect to'the application of diesel- use as onsite power r j nuclear power generator units. IEEE Std 308-1974 is en- plants be selected with ic capacity and dorsed, with certain exceptions, by Regulatory be qualified for v Guide 1.32, "Criteria for Safety-Related Electric Power Systems for Nuclear Power wThe substantial her of ges in this revision has made Plants. "

it impractical to the c ges wit* es in the margin.

'Copies e the Institute of Electrical and A knowledge of the characteristics of each Electronics In ..n ited Engineering Center, 345 East

47th Street, ork, New York 10017. load is essential in establishing the bases for USNRC REGULATORY GUIDES Comments should be sMnt to the Secrety of the Conmi;slon, U.S. Nudcer Regulatory Commurorn , Wastington, D.C. 26. Attention: Dockasth and Regulatney Guides re Issued to descrbe and rnake available to the public Sevice Branch.

methods acceptable to the NRC staff of specific parts of the commlssiora's regultionts, to delinestedvt sdb the staff In avalu- The guides are Issued Inthe following ten broad divisioin:

atg spec probles or postulated accidents. or to provide guidance to applicants. Regulatory Guides ae not sutbstitutes for regulations, and corn- 1. Power React" B. Products plence with them Is not requked. Methods end solutions different from those 2. Reseerch end Teat Reactors 7. Transportation set out Inthe guides wil b acceptable If they provide a b"si for the findings 3. Fuels and Materiab Factites & Occupational Health re=ui to the issgirce or continuance of a pewrh or Bse e by the 4. Environmental and Sitng 9. Antitrust and Financial Review Cornwitiuo* rLMatmerilsand Plant protection 10. General Comments and suggestions for Imroernemeis In tees gudes are encouraged Requests for single copies of Isued guides Iwit-h may be reproducedl or for at Imes, end guides wil bee rwl sd, aspramopas, to accommodate corn- placerment on en autonlatic: distribution list for single copies of fuaum guldes mene= and to reflect new rmt or aperen*e. Howeve. corment t, In s ief*cdivslons should be ,de In wrtltng to the US. NudIsr Reguatory this gtuld. If eeed wlfhn about two mond afte Its Issuance, wil be Cornenssion, Washingion, D.C. I, Attentio: Okector, D,4lon of wfttleft useful In awluating the need for an eauly r .evilon. Technical Informaiwon and Document Control.

the selection of a diesel-generator unit that is generator unit so that it exceeds the sum of able to accept large loads in rapid succession. the loads needed at any one time. A more accu- The majority of the emergency loads are large rate estimate of safety loads is possihle duringl induction motors. This type of motor draws, at the operating license stage of review because full voltage, a starting current five to ten detailed designs have been completed and times its rated load current. The sudden large preoperational test data are available. This increases in current drawn from the diesel permits the consideration of a somewhat less generator resulting from the startup of induc- conservative approach, such as operation with tion motors can result in substantial voltage safety loads within the short-time rating of the reductions. The lower voltage could prevent a diesel-generator unit.

motor from starting, i.e. , accelerating its load to rated speed in the required time, or cause a

C. REGULATORY POSITION

running motor to coast down or stall. Other loads might be lost if their contactors drop Conformance with the requirements of IEEE

out. Recovery from the transient caused by Std 387-1977, "IEEE Standard Criteria for starting large motors or from the loss of a Diesel-Generator Units Applied as Standby large load could cause diesel engine overspeed Power Supplies for Nuclear Power Generating which, if excessive, might result in a trip of Stations," dated June 17, 1977, is acceptable the engine. These same consequences can also for meeting the requirements of the principal result from the cumulative effect of a sequence design criteria and qualification testing of of more moderate transients if the system is not diesel-generator units used as onsite electric.

permitted to recover sufficiently between suc- power systems for nuclear power plants subject cessive steps in a loading sequence. to the following:

Generally it has been industry practice to 1. When the characteristics of loads are not specify a maximum voltage reduction of 10 to 15 accurately known, such as during the con- percent when starting large motors from large- struction permit stage of design, each diesel- capacity power systems and a voltage reduction generator unit of an onsite power supply of 20 to 30 percent when starting these motors system should be selected to have a continuous from limited-capacity power sources such as load rating (as defined in Section 3.7.1 of IEEE

diesel-generator units. Large induction motors Std 387-1977) equal to or greater than the sum can achieve rated speed in less than 5 seconds of the conservatively estimated loads needed to when powered from adequately sized diesel- be powered by that unit at any one time. In generator units that are capable of restoring the absence of fully substantiated performance the voltage to 90 percent of nominal in about 1 characteristics for mechanical equipment such second. as pumps, the electric motor drive ratings should be calculated using conservative esti- Protection of the diesel-generator unit from mates of these characteristics, e.g., pump excessive overspeed, which can result from a runout conditions and motor efficiencies of 90%

loss of load, is afforded by the immediate oper- or less.

ation of a diesel-generator unit trip, usually set at 115 percent of nominal speed. In addi- 2. At the operating license stage of review, tion, the generator differential trip must oper- the predicted loads should not exceed the ate immediately in order to prevent substantial short-time rating (as defined in Section 3.7.2 damage to the generator. There are other pro- of IEEE Std 387-1977) of the diesel-generator tective trips provided to protect the diesel- unit.

generator units from possible damage or degra- dation. However, these trips could interfere 3. During preoperational testing, the pre- with the successful functioning of the unit dicted loads should be verified by tests.

when it is most needed, i.e. , during accident conditions. Experience has shown that there 4. In Section 5.1.1, "General," of IEEE Std have been numerous occasions when these trips 387-1977, the requirements of IEEE Std 308- have needlessly shut down diesel-generator 1974 should be used subject to the regulatory units because of spurious operation of a trip position of Regulatory Guide 1.32.

circuit. Consequently, it is important that measures be taken to ensure that spurious ac- 5. Section 5.1.2, "Mechanical and Electrical tuation of these other protective trips does not Capabilities," of IEEE Std 387-1977 should be prevent the diesel-generator unit from supplemented with the following:

performing its function.

"Each diesel-generator unit should be capa- The uncertainties inherent in estimates of ble of starting and 'accelerating to rated safety loads at the construction permit stage of speed, in the required sequence, all the design are sometimes of such magnitude that it needed engineered safety feature and emer- is prudent to provide a substantial margin in gency shutdown loads. At no time during the selecting the load capabilities of the diesel- loading sequence should the frequency and generator unit. This margin can be provided voltage decrease to less than 95 percent of by estimating the loads conservatively and nominal and 75 percent of nominal, respec- selecting the continuous rating of the diesel- tively"b Frequency should be restored to

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• within 2 percent of nominal, and voltage conditions. The design of the bypass should be restored to within 10 percent of circuitry should satisfy the requirements nominal within 60 percent of each load- of IEEE Std 279-1971 at the diesel- sequence time interval. (A greater percent- generator system level and should age of the time interval may be used if it can include the capability for (I) testing the be justified by analysis. However, the load- status and operability of the bypass sequence time interval should include suffi- circuits, (2) alarming in the control room cient margin to account for the accuracy and abnormal values of all bypass param- repeatability of the load-sequence timer.) eters, and (3) manually resetting of the During recovery from transients caused by trip bypass function. (Capability for step load increases or resulting from the automatic reset is not acceptable.)"

disconnection of the largest single load, the speed of the diesel-generator unit should not 9. Section 5.6.3. 1, "Surveillance Systems," or exceed the nominal speed plus 75 percent of IEEE Std 387-1977 should be supplemented with the difference between nominal speed and the the following:

overspeed trip setpoint or 115 *percent of "In order to facilitate trouble diagnosis, the nominal, whichever is lowei. Further, the surveillance system should indicate which of transient following the complete loss of load the diesel-generator protective trips is acti- should not cause the speed of the unit to vated first."

attain the overspeed trip setpoint."

10. In Section 6.3, "Type Qualification Test-

6. In Section 5.4, "Qualification," of IEEE ing Procedures and Methods," of IEEE Std 387- Std 387-1977, the qualification testing require- 1977, the requirements of IEEE Std 344-1975, ments of IEEE Std 323-1974, "IEEE Standard for "Recommended Practices for Seismic Qualifica- Qualifying Class IE Equipment for Nuclear tion of Class 1E Equipment for Nuclear Power Power Generating Stations,"' should be used Generating Stations," for seismic analysis or subject to the regulatory p*osition of Regulatory seismic testing by equipment manufacturers Guide 1.89, "Qualification of C!ass IE Equip- should be used subject to the regulatory posi- ment for Nuclear Power Plants." tion of Regulatory Guide 1.100, "Seismic Quali- fication of Electric Equipment for Nuclear

7. Section 5.5, "Design and Application Con- Power Plants."

siderations," of IEEE Std 387-1977 should be supplemented with the following: 11. The option indicated by "may" in Sec- tion 6.3.2(5)(c) of IEEE Std 387-1977 should

"Diesel-generator units should be designed to be treated as a requirement.

be testable during operation of the nuclear power plant as well as while the plant is shut 12. Section 6.5, "Site Acceptance Testing,"

down. The design should include provisions and Section 6.6, "Periodic Testing," of IEEE

so that the testing of the units will simulate Std 387-1977 should be supplemented by Regu- the parameters of operation (outlined in latory Guide 1.108.

Regulatory Guide 1.108, "Periodic Testing of Diesel-Generator Units Used as Onsite 13. Section 4, "Reference Standards," of Electric Power Systems at Nuclear Power IEEE Std 387-1977 lists additional applicable Plants") that would be expected if actual IEEE standards. The specific applicability or demand were to be placed on the system. acceptability of these referenced standards has been or will be covered separately in other

"Testability should be considered in the regulatory guides, where appropriate.

selection and location of instrumentation sen- sors and critical components (e.g., gover-

D. IMPLEMENTATION

nor, starting system components), and the overall design should include status indica- This proposed guide has been released to tion and alarm features. Instrumentation encourage public participation in its develop- sensors should be readily accessible and ment. Except in those cases in which an appli- designed so that their inspection and calibra- cant proposes an acceptable alternative method tion can be verified in place." for complying with specified portions of the Commission's regulations, the method to be

8. Section 5.6.2.2, "Automatic Control," of described in the active guide reflecting public IEEE Std 387-1977 should be supplemented with comments will be used in the evaluation of

,the following: applications for construction permits docketed after the implementation date to be specified in

(3) "With the exception of the engine over- the active guide. This implementation date will speed trip and the generator differential in no case be earlier than July 1979.

trip, all diesel-generator protective trips should be either (1) implemented with If an .applicant wishes to use this draft guide two or more independent measurements in an application docketed prior to the imple- for each trip parameter with coincident mentation date, the pertinent portions of the logic provisions for trip actuation or (2) application will be evaluated on the basis of automatically bypassed during accident this draft guide.

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