ML19337A969
| ML19337A969 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 08/20/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19337A953 | List: |
| References | |
| TASK-08-02, TASK-8-2, TASK-RR NUDOCS 8010010101 | |
| Download: ML19337A969 (10) | |
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- SEP TECHNICAL EVALCATION TOPIC VIII-2 ONSITE EMERGENCY POWER SYSTEMS - DIESEL GENERATOR HADDAM NECK
1.0 INTRODUCTION
The objective of the review is to determine if the ensite AC generator for the Ehddam !' ck thelear Station'has sufficient capacity and capability e
to supply the required automatic safety loads during anticipated occurrences and/or in the event of postulated accidents af ter loss of o f fsite power.
The requirement that the onsite electric pcwer supplies have capacity and capability to complete the required safety functions is contained in General Criterion III, "De si' n Control," o f Appendix 3, " Quality a
Assurance Criteria for Nuclear Power Plant 10 C7R Part 50 includes a requirement that measures be provided for veri-fying or checking the adequacy of design by design reviews, by the use of alternate or simplified calculationa1 methods, or by the performance of a suitable testing program.
Re gulatory Guides, IEEE Standards, and 3 ranch Technical Positions which provide a basis acceptable to the NRC staf f for compliance with GDC17 and Criterion III include:
Regulatory Guide 1.9, " Selection of Diesel Generator Se t Capacity for Standby Power Supplie s;" Regulatory Guide 1.108,
" Periodic Testing of Diesel Generators Used as Onsite Power Systems at Nuclear Power Plants"; IEEE Standard 38 7-1977, " Criteria for Diesel Generator Units Applied as Standby Power Supplies for Nuclear Power Stations;" 3TP ICS32, " Diesel-Generator Reliability Qualification Testing";
and ST? ICS317, " Diesel Generator Protective Trip Circuit 3ypasses."
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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-l and III-12 will evaluata the diesel-generator qualification.
2.0 CRITIRIA 2.1 Diesel Generator Leading. Regulatory Leide 1.9, " Selection of Diesel-Generator Se t Capacity for Standby power Supplie s," provides the basis acceptable to the NRC s taf f for loading diesel-generator units.
Th e following criterion is used in this report to determine compliance with current licensing requirements:
(1) The automatically-connected loads on each diesel-generator unit should noc exceed the 2000-hour rating.
(loads must be conservatively estimated utilizing the nameplate ratings of motors and transformers with motor efficiencies of 90* or les s.
When available, actual measured loads can be used.)
2.2 Svpue; o f rro tec t ive Tr ip s. Branch Technical Position (BTP)
ICSB 17, " Diesel-Generator Protective Trip Circuit Bypasses," specifies l
tha t :
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(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 o ther trips, in addition to the engine overspeed and generator differential, are retained for accident con-dicions, an 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 :oincident logic.
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2.3 Diesel Generator Testing.
Pegulatory Guide 1.108, " Periodic Te sting Of Diesel Generator Units Used as Onsite Electrical Power ',ys tems at !nselear Power Plant s",
state s that:
(1) Te sting of diesel-generator units, at least once every l
18 month s, should (a) Demonstrace proper startup operation by simulating loss of all ac voltage and demonstrate that the j
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 racing of the diesel generator and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at a load equivalent to the 2-hour rating of the diesel generator. Verify that voltage and frequency requirements are maintained.
he test should also verify that the cooling sys tem fune-tions within design limit s.
(d) Demonstrate proper operation during diesel-generator load shedding, including a test of the loss of the largest single load and of ecmplete loss of load, and verify that the voltage require-ments are met and that the overspeed limits are not exceeded.
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(e) Demonstrace functional capability at full-load temperature conditions by rerunning the test phase i
outlined in (a) and (b), immediately following (c), above.
i (f) Demonscr' ate the ability to synchronize the diesel generator 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.
(g) Demonstrate that the engine will perform properly if switching f rom one fuel-oil supply system to another is a part of the normal operating proced-ure to satis fy the 7-day s torage requiremen:.
(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.
l (2)
Testing of redundant diesel-generator units during normal plant operation should be performed indepen-dently (nonconcurrently) 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 inter-dependence may have been af fected or every 10 years (during a plant statdown), 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.
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(3) Periodic testing of diesel-generator units during nor-mal 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 components o f the diesel-generator unit required for automatic startup are operable.
(b) Demonstrate full-load-carrying capability (contin-uous 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 parfor-mance.
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:
1 (a) If the number of failures in the last 100 valid tests is one or zero, the tes t interval should be not more than 31 days.
(b)
If the number of failures in the last 100 valid tests is two, the test interval should be not more than 14 days.
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gt (c)
If the number of failures in the last 100 valid tests is three, the test interval should be not more than 7 days.
(d) if the number of failures in the last 100 valid tests is four or more, the tes t interval should be not more than 3 days.
i 3.0 DISCUSSION AND EVALCATION The redundant diesel generators' loading and use of protective trips are identical. Therefore, the discussion and evaluation of one diesel generator, which follows, is identical for the other diesel generator.
3.1 Diesel-Generator toading Discussion. On July 27, 1979, CYAPCo provided a list of loads automatically connected to the diesel generators in the event of a LOCA concurrent with a isss of offsite power.1 The submitted load lists utilizing nameplate ratings to determine load values indicate a total load o f 2619 kW on each generator. Using a 90: efficiency factor, as specified in RC 1.9 when nameplace ratings are used, the calculated maximum lead for each generator is 2910 kW.
The maximum step load change is 1238 kW (45% of continuous capac-ity), which occurs ten seconds af ter the diesel generator start signal.
Eaddam Neck Techni:a1 Specifications requ'.re a two-hour full load test o f each diesel generator monthly.2 Evalua tion. The calculated maximum automatically-connected lead to either generator is 2910 kW.
The diesel generators rated load capacity is 2950 kW for 30 minutes and 2850 kW continuous.3 Therefore, the total automatically-cennected load, which is 99% o f the generator 30-minute 6
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rating and 102% of the continuous reting, exceeds the RG 1.9 diesel generator loading limits o f 90% of the 3 0-minute rating and 100% o f the continuous rating.
3.2 Bypass o f Protective Trips Disces s io n.
On May 16,1977, CYAPCo provided a lis t o f pro-tective trips which render the diesel generators incapable of responding to an automatic emergency start signal.' iSe proceetive trips which are not bypassed under emergency conditions are overspeed, dif ferential, ov ercurrent, and reverse power. None o f the trip parameters use multiple sensors and coincident lo gic.
Evaluation. The overcurrent and reverse power protective trips are not bypassed under emergency conditions.
Neither trip uses redundant i
parameter sensors and coincident logic. Th ere fore, the diesel generator protective trips do not meet the requirement of BTP ICS317.
3.3 Diesel Generator Testing Discus s io n.
Haddam Neck Technical Specifications, para-graph 4.5, require diesel-generator testing as f ollows:
(1) Manuelly initiated demonstration o f the ability o f the 1
diesel generators to start and deliver power up to the expected maximum emergency loading, when operating in parallel with other power sources.
This test will be conducted monthly on each diesel generator.
No rma' plant operation will not be af fected.
The duration o f the test shall be at least two hour s.
1 (2) Demonstration o f the readiness o f the systems to automatically start and restore power to vital equipment by iniciating a loss o f normal ac power supply to each emergency power system separately.
This test will be conducted during each refueling interval.
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Evaluatio n.
Diesel-generator testing defined in the plant Technical Specifications address the criteria listec in paragraph 2.3 to the following extent:
(1) (a) Voltage, frequency and time limits ao specified (bt Voltage and frequency limits no'; specified (c) Load level and duration not specified (d)
Not addressed (e) Not addressed (f)
Not addressed (g) No t addressed (h)
No t addressed (2) Not addressed (3) (a) Automatic start components not addressed; voltages frequency and time limits not specified (b) Acceptable (4) No t addressed.
The Technical Specifications do not meet current licensing criteria for diesel-generator testing. Diesel-generator failure data will be extracted by NRC f rom Licensee Event Reports and will be considered in the final evaluation o f testing adequacy.
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l 4.0 SUMPA RY The Haddam Neck diesel generator loading does not comply with current licensing requirements as the total calculated load exceeds RG 1.9 30-minute and continuous limits by 9% and 2%, respectively. Th e bypas s o f diesel generator protective trips is also not in agreement with current NRC staff guidelines. Diesel generator testing, as specified by plant Technical Specifications, does not meet current licensing criteria.
The review of quiaification of the diesel geneatres will be completed with SEF Topics III-1, seismic Qualification, and III-12, Environmental Qualification.
5.0 REFERENCES
1.
Memorandum, NUSCO (E. P. Perkins) to NRC (T. V. '4ambach) dated July 27, 1979 2.
Technical Specifications for the Connecticut Yankee Atemic Power Comoany, Haddam Neck Plan t, Paragraph 4.5, dar.ed December 27, 1974.
3.
Final Design and Safe ty Analysis, Paragraph 9.5, updated through April 1, 1977.
4.
Le eter, CYAPCo (D. C. Switzer) to NRC (A. Schwencer) dated May 16, 1977.
3.
General De sign Criterion 17, " Electric Power Sys tem," o f Appendix A,
" General Des ign Criteria of !bclear Power Plant s,"
to 10 CRF Par t 50,
" Domestic Licensing of Production and Utilization Facilities."
6.
General Design Criterion III, " Design Control," of Appendix 3,
" Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plant s," to 10 CRF Part 30, " Domestic Licensir.g of Production and Utilization Facilities."
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7.
"St.andard Criteria for Clas s IE Power Systems and Nuclear Power Generating Stations," IEEE Std. 308, 1974, paragraph 5.2.4.
8.
" Criteria for Diesel-Generator Units Applied as Standby Tower Supplies for Nuclear Power Stations," IEEE Std. 387, 1977.
9.
" Selection of Diesel Generator Set Capacity for Standby Power l
Supplies," Re gula tory Guide 1.9.
10.
" Periodic Testing of Diesel Generators Used as Onsite Power Sys-tems at Nuclear Plants," Regulatory Guide 1.108.
11.
" Diesel-Generator Reliability Qualification Testing", BTP ICS32 (P SB).
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" Diesel-Generator Protective Trip Circuit 3ypasses," :T! ICSB17 (PS B).
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