ML20058A730
| ML20058A730 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 05/31/1982 |
| From: | Farmer F EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6425, TASK-08-02, TASK-8-2, TASK-RR EGG-EA-5882, EGG-EA-5882-01, EGG-EA-5882-1, NUDOCS 8207220004 | |
| Download: ML20058A730 (13) | |
Text
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EGG-EA-5882 May 1982 l
l SYSTEMATIC EVALUATION PROGRAM, TOPIC VIII-2, DIESEL GENERATOR, BIG ROCK POINT aRe W 12eseacek and or $kssea.L. Assts/ane &
F. G. Farmer U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory
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' ?Q This is an informal report intended for use as a preliminary or working document Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6425
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p 8207220004 820531 PDR RES 8207220004 PDR
E edaho Inc fOHMiG40W8 eRev 0)8/1 INTERIM REPORT Accession No.
Report No.
EGG-EA-5882 Contract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
Systematic Evaluation Program, Topic VIII-2, Diesel Generatne, Big Rock Point Type of Document:
Informal Report Author (s):
F. G. Farmer Dite of Document:
May 1982 R2sponsible NRC individual and NRC Office or Division:
R. F. Scholl, Jr., Division of Licensing This document was prepared primarily for preliminary orinternal use. it has not received full review and approval. Since there may be substantive changes, this document should not be considered final.
EG&G Idaho, Inc.
\\0 Prepared for the ls' U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 761D01570 NRC FIN No. A6425 l
INTERIM REPORT l
1
l 1
0192j O
SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-2 DIESEL GENERATOR BIG ROCK POINT Docket No. 50-155 May 1982 F. G. Farmer EG&G Idaho, Inc.
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'O May 12, 1982
1 e
ABSTRACT This SEP technical evaluation, for Big Rock Point, reviews the loading of the diesel-generator, use of protective trips during accident conditions, and periodic testing.
FOREWORD This report is supplied as part of the " Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)"
being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc.,
Reliability and Statistics Branch.
The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05, FIN A6425.
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1 ii i
1 CONTENTS 1.0 I N TR O D U C T I O N....................................................
1 2.0 CRITERIA........................................................
I 2.1 Di es el Ge n er a tor Lo a di n g..................................
1 0
2.2 Byp ass o f P ro te c t ive Tr i ps................................
2 2.3 D i es el Gen er a tor Tes ti n g..................................
2 3.0 D I S CU SS IO N AND E VALV AT IO N.......................................
4 3.1 Diesel Gener ator Loa di ng..................................
4 3.2 Bypass of Protective Trips................................
5 3.3 D i es el Gen er a tor Te s ti n g..................................
6 4.0
SUMMARY
7 S.0 REFERENCES......................................................
7 h
SYSTEMATIC EVALUATION PROGRAM TOPIC VIII-2 DIESEL GENERATOR BIG ROCK POINT
1.0 INTRODUCTION
The objective of the review is to determine if the onsite AC generator for the Big Rock Point Nuclear Station has sufficient capacity and 0
capability to supply the required automatic safety loads during anticipated occurrences and/or in the event of postulated accidents af ter loss of offs ite power. The requirement that the onsite electric power supplies have capacity and capability to complete the required safety functions is contained in General Design Criteria 17.
Criterion III, " Design Control," of Appendix B, " Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 includes a requirement that measures be provided for verifying or check ing the adequacy of design by design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program.
Regulatory Guides, IEEE Standards, and Branch Technical Positions which provide a basis acceptable to the NRC staff for compliance with GDC17 and Criterion III include:
Regulatory Guide 1.9, " Selection of Diesel-Generator Set Capacity for Standby Power Supplies"; Regulatory Guide 1.108, " Periodic Testing of Diesel-Generators Used as Onsite Power Systems at Nuclear Power Plants"; IEEE Standard 387-1977, " Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Nuclear Power Stations"; BTP ICSB2, " Diesel-Generator Reliability Qualification Testing";
and BTP ICSB17, " Diesel-Generator Protective Trip Circuit Bypasses."
Specifically, this review evaluates the loading of the diesel-generator, bypasses of protective trips during accident conditions and periodic testing. The SEP reviews for Topics III-1 and III-12 will evaluate the diesel-generator qualification.
2.0 CRITERIA 2.1 Diesel Generator Loading.
Regulatory Guide 1.9, " Selection of Diesel-Generator 5et Capacity for Standby Power Supplies," provides the basis acceptable to the NRC staff for loading diesel-generator units. The following criterion is used in this report to determine compliance with current licensing criteria:
9 (1) The automatically-connected loads on each diesel-generator unit should not exceed the 2000-hour rating.
(Loads must be conservatively estimated utilizing the nameplate ratings of motors and transformers with motor efficiencies of 90% or less.
When available, actual measured loads can be used.)
1
2.2 Bypass of Protective Trips. Branch Technical Position (BTP)
ICSB 17, "Diesei-benerator Protective Trip Circuit Bypasses," specifies that:
(1) The design of standby diesel-generator systems should retain only the engine overspeed and the generator differential trips and bypass all other trips under an accident condition.
(2)
If other trips, in addition to the engine overspeed and generator differential, are retained for accident conditions, ar acceptable design should provide two or more independent measurements of each of these trip parameters. Trip logic should be such that diesel-generator trip would require specific coincident logic.
2.3 Diesel Generator Testing.
Regulatory Guide 1.108, " Periodic Testing of Diesel Generator Units Used is Onsite Electrical Power Systems at Nuclear Power Plants," states that:
(1)
Testing of diesel-generator units, at least once every 18 months, shoul d:
(a) Demonstrate power startup operation by simulating loss of all AC voltage and demonstrate that the diesel-generator unit can start automatically and attain the required voltage and frequency within acceptable limits and time.
(b) Demonstrate proper operation for design-accident-loading sequence to design-load requirements and verify that voltage and frequency are maintained within required limits.
(c)
Demonstrate full-load-carrying capability for an interval of not less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of which 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> should be at a load equivalent to the continuous rating of the diesel-generator and two hours at a load equivalent to the 2-hour rating of the diesel-generator. Verify that voltage and frequency requirements are naintained.
The test should also verify that the cooling system functions within design l imi ts.
(d) Demonstrate proper operation during diesel-generator load shedding, including a test of the loss of the largest single load and of complete loss of load, and verify that the voltage requirements are met and that the overspeed limits are not exceeded.
l (e) Denonstrate functional capability at full-load temperature conditions by rerunning the test phase outlined in (a) and (b), immediately following (c), above.
(f)
Demonstrate the ability to synchronize the diesel-generator l
unit with offsite power while the unit is connected to the emergency load, transfer this load to the offsite power, isolate the diesel-generator unit, and restore it to standby status.
s 2
(g)
Demonstrate that the engine will perform properly if switching from one fuel-oil supply system to another is a part of the normal operating procedure to satisfy the seven-day storage requirement.
(h)
Demonstrate that the capability of the diesel-generator unit to supply emergency power within the required time is not impaired during periodic testing under (3), below.
(2)
Testing of redundant diesel-generator units during normal operation should be performed independently (noncurrently) plant to minimize common failure modes resulting from undetected interdependences among diesel-generator units. However, during reliability demonstration of diesel-generator units during plant preoperational testing 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.
( 3)
Periodic testing of diesel-generator units during normal plant operation should:
(a) Demonstrate proper startup and verify that the required voltage and frequency are automatically attained within acceptable limits and time. This test should also verify that the canponents of the diesel-generator unit required for automatic startup are operable.
(b)
Demonstrate full-in-i-carrying capability (continuous rating) for an interval of not less than one hour. The test should also verify that the cooling system functions within design limits. This test could be accomplished by synchronizing the generator with the offsite power and assuming a load at the maximum practical rate.
(4)
The interval for periodic testing under (3), above (on a per diesel-generator unit basis) should be no more than 31 days and should depend on demonstrated performance.
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:
(a)
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.
e (b)
If the number of failures in the last 100 valid tests is two, the test interval should not be more than 14 days.
(c)
If the number of failures in the last 100 valid tests is three, the test interval should be not more than seven days.
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(d)
If the number of failures in the last 100 valid tests is four or more, the test interval should be not more than three days.
3.0 DISCUSSION AND EVALUATION 3.1 Diesel-Generator Loading Di scus s ion.
In the Commission Memorandum and Order, dated May 26,19TO Big Rock Point (BRP) was granted a lifetime exemption from the single-failure requirements of 10 CFR Part 50.46 and Appendix K, Paragraph 1.D.1 as applied to a Loss-of-Coolant Accident (LOCA) caused by a break in a core spray line and a concurrent single failure in the remaining core spray system.
Included in the order was plant-life exemption from the requirement that the ECCS short-term and long-term cooling functions be invulnerable to a single failure which disables onsite power assuming of fsite power is not available. This was allowed in view of the high availability of offsite power at Big Rock Point, together with improved reliability of the onsite diesel and guaranteed availability of a backup diesel for long-term cooling.
The Director's. comments note that, in view of the small size of this plant compared with the system capacity, trips of the plant due to internal causes are relatively unlikely to cause a loss of of fsite power.
l Consequent to the above action, Big Rock Point has only one onsite dies el-gen era tor.
loading list for Big Rock Point.govided the current diesel-generator (DG)
On January 19,1979, CPCo p Utilizing the submitted data, a draft evaluation of the diesel-generator loading was prepared. This evaluation indicated that the DG was loaded over the rated capacity and there was a question of its capability to provide power to the required safety loads during a LOCA with loss of offsite power. A copy of this evaluation, along with a request f 14,1979.gr additional information, was transmitted to CPCo on On Au gus t 28, 1979, CPCo transmitted to the NRC August comments on the draft evaluation, their answers to NRC questions, station operating procedures for manual loading of the DG a revision to the 2
automatic and manual loading of the diesel-generator).g (This evaluation tabulation of DG loads, and a scenario of 3.53 ft LOC showing the incorporates the latest information supplied by CPCo. CPCo submittals provide current information on the manual loading of the single diesel-generator under the following conditions, (a) loss of offsite power withogt concurrent LOCA and, (b) loss of offsite power coincident with a LOCA. '6 During each of the two conditions, CPCo supplied the nameplate (HP) rating of each motor, the measred current for each load, and the calculated KVA for each load.
The calculated KVA loading conservatively represents the actual loads on the diesel-generator since it utilizes the neasured current in determining the values. Therefore, it is not necessary to use the 90% efficiency to determine motor loads.
On loss of offsite power and after start-up of the DG, Bus 2B is automatically connected to the DG.
The load on 28 is 166.1 KVA.
After approximately 75 seconds, the load will drop to 150.3 KVA.
Current Plant l
System Operating Procedures require the operator to strip most loads from i
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Buses l A and 2A before connecting these buses to the DG.
The operator then will manually add loads to bring the DG loading to 200.9 KVA for approximately five minutes. The DG loading will then drop to 160.9 KVA.
The maximJm DG loading will occur approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the start of the LOCA.
At that time, with the start-up of the core spray pump, the DG loading will be 215.8 KVA.
The Big Rock Point Technical Specifications require a load test of the diesel-generator to 180 to 200 kW generator output for 20 minutes between each reactor operating cycle. The Technical Specifications also require monthly testing of the diesel-generator on the 2B bus with a minimum load of at least the electric fire pump.
Information provided by CPCo indicates that this test is perforned by interrupting power to the 28 bus causing the diesel-generator to autonatically start and energize the bus.
The fire pump discharge header pressure is manually bled down to cause an automatic starting of the fire pump. Und3r these conditions, a vol tage transient with a maximum voltage of 501 V and a minimum voltage of 446 V, occurs over approximately 0.75 second. A corresponding frequency transient with a maximum frequency of 62.2 Hg and a minimum frequency of 54.5 Hz occurs over a two-second interval.
NRC Regulatory Guide 1.9, Paragraph C.4 requires that the frequency and voltage (bcrease during the diesel-generator loading sequence not exceed 95% and 75% of nominal values, respectively; a larger decrease may be justified for a diesel-generator that carries only one large connected load. Since the Big Rock Point diesel-generator carries more than one load, the frequency drop to 54.5 Hz is not in compliance with current licensing criteria.
E valua tion.
The maximum loading of the diesel-generator will occ ur 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> af ter the loss of of fsite power during a LOCA.
At that time, the diesel-generator loading is expected to be 215.8 KVA.
The maximum automatically connected load of 166.1 KVA will occur af ter the diesel-generator has started and attained operating voltage and frequency.
The diesel-generator full load rating is 200 kW at 0.8 PF or 250 KVA.
The generator has neither a 2000-hour rating nor a 30-minute rating. The maximum predicted load is 86% of the full load rating and is, therefore, in compliance with current licensing criteria.
However, the frequency decrease encountered when starting the electric fire pump is less than the 95% of nominal frequency required by Paragraph C.4 of NRC Regulatory Guide 1.9 and is, therefore, not in compliance with current licensing criteria.
3.2 Bypass of Protective Trips Discuss ion.
The Commission's Memorandum and Order, dated May 26, 1976, direH&T~CPCo to:
" Modi fy the emergency diesel-generator and diesel-driven fire water pump protective trips to bypass the protective trips during accident conditions except for retention of the engine overspeed 5
and generator differential current trips, unless additional bypass trips are approved by the Director, Nuclear Reactor Re gula t ion. "
Based on BTP EICSB 17, CPCo modified the emergency diesel-generator trip circuitry to retain those trips associated with low lube oil pressure, high cooling water temperature and generator overcurrent, utilizing two independent sensors and coincidence logic, while maintaining the engine overspeed trip as originally designed.
No modifications were incorporated s
for the diesel-driven fire water pump, since the only parameter that will cause a trip is engine overspeed.
Ev al ua t ion. The NRC staf f review of the B'g Rock Point diesel-generator protective trip circuit bypasses v 2s completed in the SER for Amendment No.15 to Facility Operating License iiv..
F.
dated October 17, 1977.2 The following statement was included on Page 24 of the SER:
" Based on our review, the modifications to the emergency diesel-generator are acceptable because they (a) satisfy the criteria of BTP EICSB 17, (b) significantly enhance the reliability of the onsite power system, and (c) comply with Section (3) (iii) of the Memorandum and Order, dated May 26, 1976."
a During accident conditions the diesel-generator engine overspeed electrical trip is retained as originally designed.
All other diesel-generator protective trips utilize two sensors and coincidence logic. Therefore, the use of protective trips for the Big Rock Point diesel-generator is in agreement with BTP EICSB 17 and complies with current licensing criteria.
3.3 Diesel Generator Testing Di scuss ion.
Big Rock Point Technical Specifications, Paragraph 11.4.5.3, require diesel-generator testing as follows:
(1) During each operating cycle--test of automatic initiation sensors and load test the emergency diesel to 180 to 200 kW generator output for at least 20 minutes.
(2) Monthly--Test start diesel-generator and operate at least the fire pump as a load to 480 V Bus 2B for at least 20 minutes.
(3) Weekly--Test start the diesel-generator and run for warm-up period.
Evaluation.
Diesel-generator testing defined in the plant Technical Specifications addresses the criteria listed in Paragraph 2.3 to the following extent:
(1)
(a) Voltage, frequency and time limits not specified (b)
Sequencing, voltage and frequency not specified 6
(c) Minimum test duration is 20 minutes (d)
Not addressed (e)
Not addressed (f)
Not addressed (g)
Not applicable (h)
Not addressed 3
( 2)
Not applicable
( 3)
(a) Automatic start components not addressed; voltage, frequency and t.me limits not specified (b) Full-load test not required; minimum test duration is 20 minutes (4)
Not addressed.
The Technical Specifications do not meet current licensing criteria for diesel-generator tes ting.
Diesel-generator failure data will be extracted by NRC from Licensee Event Reports and will be considered in the final evaluation of tes ting adequacy.
4.0 SUMMAR Y The bypass of diesel-generator protective trips is in compliance with current licensing criteria.
The diesel-generator loading meets the current licensing criteria except that a frequency decrease to 91% of nominal frequency occurs when starting the electric fire pump. The maximum allowable decrease, as defined in Paragraph C.4 of RG 1.9, is 95%.
Diesel-generator tes ting, as specified by plant Technical Specifications, does not meet current licensing criteria. The review of qualifications of the diesel-geaerators will be completed with SEP Topics III-1, Seismic Qualification, and III-12, Environmental Qualification.
5.0 R EF ER ENCES 1.
Memorandum and Order, by the Commissioners, NRC in the Matter of CPCo, Big Rock Point, dated May 26,1976, page 9.
2.
Letter NRC (D. K. Davis) to CPCo (D. Bixel), dated October 17, 1977, attached report, page 11, " Safety Evaluation by the Office of Nuclear Reactor Regulation Supporting a Limited ECCS Exemption for the 1978 Operating Cycle."
3.
Letter CPCo (Vincent) to NRC (Crutchfield), dated April 21, 1982.
4 Letter CPCo (D. A. Bixel) to NRC (D. L. Zieman) dated January 19, 1979, "Addi tional I nfornation Regarding SEP Topics VI-7.8, VII-1. A, an d V I I-2. "
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5.
Letter NRC (Zieman) to CPCo (Bixel) dated August 14, 1979, Topic VIII-2, "0nsite Emergency Power Systems--Diesel Generators."
6.
Letter CPCo (Bixel) to NRC (Zieman) dated August 28,1979, " Addi tional Information Relative to SEP Topic VIII-l."
7.
General Design Criterion 17, " Electric Power System," of Appendix A,
" General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50,
" Domestic Licensing of Production and Utilization Facilities."
s 8.
General Des ign Criterion III, " Design Control," of Appendix B,
" Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities."
9.
" Standard Criteria for Class IE Power Systems and Nuclear Power Generating Stations," IEEE Std. 308, 1974, paragraph 5.2.4.
10.
" Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Nuclear Power Stations," IEEE Std. 387, 1977.
11.
" Selection of Diesel Generator Set Capacity for Standby Power Supplies," Regulatory Guide 1.9.
12.
" Periodic Testing of Diesel Generators Used as Onsite Power Systems at Nuclear Plants," Regulatory Guide 1.108.
13.
" Diesel-Generator Reiiability Qualification Testing," BTP ICSB2 (PSB).
14
" Diesel-Generator Protective Trip Circuit Bypasses," BTP ICSB17 (PSB).
15.
Big Rock Point " Technical Speci fications," pages 1-17, paragraph 11.4.5.3.
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