ML20003C169
| ML20003C169 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 01/31/1981 |
| From: | Weber D EG&G IDAHO, INC., EG&G, INC. |
| To: | Shemanski P Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6429 EGG-EA-5343, NUDOCS 8102260750 | |
| Download: ML20003C169 (13) | |
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TECIINICAL EVALUATION REPORT, ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES, JOSEPil M. FARLEY NUCLEAR POWER STATION, UNIT NOS. 1 AND 2, DC4KET NOS.
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D. A. Weber 1
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l 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 g
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FORW EG&G M16 (Rev 11 Flig INTERIM REPORT Accession No.
Report No.
EGG-EA-5343 Contract Program or Project
Title:
Electrical, Instrumentation and Control System Support Subject of this Document Adequacy of Station Electric Distribution System Voltages, Joseph M. Farley Nuclear Power Station, Unit Nos. I and 2 Type of Document:
Technical Evaluation Report Author (s):
D. A. Weber NRC Researc1 anc Tec1nica Date of Document:
N Ass. tance Repor:
is January 1981 Responsible NRC Individual and NRC Office or Division:
Paul C. Shemanski, Division of Licensing This document was prepared primarily for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes, this document should not be considered final.
l EG&G Idaho, Inc.
Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 76lD01570 NRC FIN No.
AM29 INTERIM REPORT L
0278J ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES JOSEPH M. FARLEY NUCLEAR POWER STATION - UNIT NOS. 1 AND 2 Docket Nos. 50-348 and 50-364 January 1981 D. A. Weber Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.
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ABSTRACT I
The Nuclear Regulatory Commission has required all licensees to analyze the electric power system at each nuclear station. This review is to deter-nine if the. onaite distribution system in conjunction with the offsite power sources has' sufficient capacity and capability to automatically start and i
operate all required safety loads within the equipment voltage ratings.
This Technical Evaluation Report reviews the submittals for the Joseph M. Farley Nuclear Power Station.
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' The offsita power sources, in conjunction with the onsite distribution i
system, has been shown to have sufficient capacity and capability to con-tinuously operate all required safety related loads, within the equipment rated voltage limits, in the event of either an anticipated transient or an accident condition.
FOREWORD This' report is supplied as part of the selected Electrical, Instrumen-t tation, and' Control Systems (EICS) issues program being conducted for the
-U.S. Nuclear-Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Operating Reactors, by EG&G Idaho, Inc., Reliability and Statis-tics Branch.
The U.S.-Nuclear Regulatory Commission funded the work under the auth-orization. entitled " Electrical, Instrumentation, and Control System Sup-port," B&R 20 19 01 03, FIN No. A6256.
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CONTENTS
1.0 INTRODUCTION
1 2.0 DESIGN BASIS CRITERIA.............................................
1 3.0 SYSTEM DESCRIPTION................................................
2 4.0 ANALYSIS DESCRIPTION..............................................
2 4.1 Analysis Conditions..........................................
2 4.2 Analysis Results.............................................
5 4.J Analysis Verification........................................
5 5.0 EVALUATION........................................................
6
6.0 CONCLUSION
S.......................................................
7 7.0 RE FE RE NC E S........................................................
8 FIGURE 1.
Farley electrical single-line diagram.............................
3 TABLES L
1.
Class IE Equipment Voltage' Ratings and
- Analyzed Worst Case Load Terminal Voltages 4
2.
Comparison _of Analyzed Voltages and Undervoltage Relay Setpoints......................................
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ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES JOSEPH M. FARLEY NUCLEAR STATION - UNIT NOS.1 AND 2
1.0 INTRODUCTION
An event.at the Arkansas Nuclear One station on September 16, 1978 is described in NRC IE Information Notice No. 79-04.
As a result of this event, station conformance to General Design Criteria (GDC) 17 is being
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questioned at all nuclear power stations. The NRC, in the generic letter of August 8,1979, " Adequacy of Station Electric Distribution Systems Vclt-ages," I required each licensee to confirm, by analysis, the adequacy of the voltage at the class lE loads. This letter included 13 specific guide-lines to be followed -in determining if the load terminal voltage is adequate to start and continuously operate the class lE loads.
In response to the NRC generic letter, Alabama Power Company (APC) submitted a voltage analysis on December 11, 1979.2 This review is based 1977,3 January 15, on this submittal, APC's submittals on November 7,7, Auggt 6
1979 4 May 1, 1980,5 J ly 17, 1980, July 30, 1980 7,
3 1980, October 7, 1980, NRC memorandum of July 25, 1980 and August 13, 198011, and the Final Safety Analysis Report (FSAR).
Based on the information supplied by APC, this report addresses the capacity and capability of the onsite distribution system of the Joseph M. Farley Nuclear Power Station, in conjunction with the offsite power system, to maintain the voltage for the required class lE equipment within acceptable limits for the worst-case starting and load conditions.
2.0 DESIGN BASIS CRITERIA The positions applied in determining the acceptability of the of fsite voltage conditions in supplying power to the class IE equipment are derived from the following:
1.
General Deusgn Criterion 17 (CDC 17), " Electrical Power Systems," of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50.
2.
General Design Criterion 5 (GDC 5), " Sharing of struc-tures, Systems, and Components," of Appendix A,." General Design Criteria for Nuclear Power Plants," of 10 CFR 50.
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.3.
General Design Criterion 13 (GDC 13), " Instrumentation and Control," of Appendix A,'" General Design Criteria for Nuclear Power Plants," of -10 CFR 50.
- NRC Researca anc "ec'ini Assistance Report -
4.
IEEE Standard 308-1974, " Class IE Power Systems for tiuclear Power Generating Stations."
5.
Staff positions as detailed in a letter sent to the licensee, dated August 8, 1979.1 6.
ANSI C84.1-1977, " Voltage Ratings for Electric Power Systems and Equipment (60 Hz)."
Six review positions have been established from the NRC analysis guide-lineal and the above-listed documents. These positions are stated in Section 5.
3.0 SYSTEM DESCRIPTION A single-line diagram of the AC electrical system at Farley Unit 1 is shown in Figure 1.
Tne Farley Unit 2 is similar.
Two startup auxiliary transformers, connected to the 230kV switchyard supply the load of the 4.16 kV buses H, K, and F of train A (transformer IA) and G, L, and J of train B (transformer IB). Either transformer can supply ooth trains.
Each unit is provided with seventeen 600V load centers and thirteen 600V and 208V motor-control centers. Seven of the load center and eleven of the motor control centers are shared between the units, and can be sup-plied from either the Unit 1 or Unit 2 distribution system. All class lE 600V buses and loads are supplied from the 4160V IE buses.
Table 1 shows the operating ratings and settings of equipment at the Farley Station.
4.0 ANALYSIS DESCRIPTION 4.1 Analysis Conditions. APC has determined by grid stability analy-sis that the maximum expected 230kV offsite grid voltage is 241.27kV (104.9%) and the minimum 229.54kV (99.8%).
APC has analyzed each offsite source to the onsite distribution system under extremes of load and offsite voltage conditions to determine the terminal voltages to IE equipment. The worst case maximum class 15 equip-ment terminal voltages occur under the following conditions:
1.
The 230kV switchyard is at the maximum expected voltage.
2.
Unit 1 is on post-LOCA af ter plant shutdown with lighting and HVAC loads running.
3.
Unit 2 is in the refueling mode with lighting and HVAC loads running.
The worst case minimum voltage conditions occur when:
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TABLE 1 CLASS lE EQUIPMENT VOLTAGE RATINGS AND ANALYZED WORST CASE TERMINAL VOLTAGES
(% of nominal voltage) a Maximum" Minimum Analyzed Equipment Condition Rated Analyzed Rated Steady State Transient 4000V Motors Start 75 88.71 Operate 110 106.36 90 92.99 550V Motors Start 75 77.75 Operate 110 110.39 90 93.57 76.27 75 200V Motors Start Operate 110 110.36 90 92.9 71 71.27 600V Starters Pickup 55 71.27 (MCCs)'
-Dropout Operate 110 101.19 85 85.77 71 73.86 208V Starters Pickup 55 73.86 L
(MCCs)
Dropout Operate 110 106.11 85 89.32-
'120V Other 120V 110' b
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b Equipment a.
230kV switchyard: maximum 104.9%, minimum 99.8%.
b.
All lower voltage instrumentation and other equipment are supplied from inverters / regulated transformers.
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1.
The 230kV switchyard is at its minimum expected voltage.
2.
Unit I unit _ transformers are out of service.
3.
Unit 1 is in a LOCA condition with all possible Unit 1 loads and all'possible Unit 2 shutdown and normal loads supplied from both Unit I startup auxiliary trans-formers IA and IB.
The worst case transient condition' occurs with the start of a 3,000 hp Condensate Pump coincident with the start of the LOCA Ic. ads.
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4.2 Analysis Result. Table 1 shows the projected worst case class 1E equipment terminal voltages, and Table 2 -hows a comparison of analyzed voltage and undervoltage relay setpoints.
TABLE 2 COMPARISON OF ANALYZED VOLTAGES AND UNDERVOLTAGE RELAY SETPOINTS
(% of nominal voltage)
Minimum Analyzed Relay Setpoint Location / Relays Voltage Time Voltage (Tolerance)
Time 4160V bus 1Fa Degraded grid 89.65 continuous 89.65 (+1) 20-30 see Loss of. grid 75.97 6 sec 72.00 3.6 see
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APC submitted voltages and location of U/V and LOV relays.
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4.3 Analysis Verification. The voltage analysis provided by APC in their~ submittal of December 11, 1979,2 is for Unit 1.
However, since
-Unit 1 is presently operating, a test was performed on Unit 2.
The string of buses monitored on Unit 2 are similar to_the buses analyzed for Unit 1.
9 In regard to' Unit'l testing, the licensee has submitted -detailed acceptable justification supporting the applicability of the Unit 2
. testing, combined with the prior Unit 1 test 2, for verifying the Unit 1 design.
The details of ' the' t'est8,9,11 to verify the results are as follows:
1.
APC measured Train B safeguards equipment electrical parameters (V, KW, KVAR) at the 230kV switchyard, 4160V Bus 2G (supplied by Startup Transformer 2B), 600V Load Center 2E, and the 600V and-208V Motor Control Cen-ters 2T.
This string of buses has been determined by analysis to exhibit the largest voltage drops during the worst. case analyzed. Nearly 100% of the Train B loads were -in operation, as well as the 7000 hp circu-
-lating water ~ pump oon the 4160V Bus 2A.-
The total load recorded is approximately 33% of the total load on Startup Transformer 2B due to a. unit trip with safety injection.
2.
The test data for each bus was converted from KW and KVAR to KVA and power factor, and these values along 5
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with the measured switchyard voltage were input to the computer. The bus voltages were than calculated using the same analytical model that was used in the worst case analysis. The test and calculated voltage were then compared and the differences noted. Justification for differences between the analytical and test results, including measurement errors, was also provided.
5.0 EVALUATION Six review positions have been established from the NRC analysis guide-linesl and tne documents listed in Section 2 of this report. Each review position is stated below followed by an evaluation of the licensee s ubmit ta ls.
Position 1--With the minimum expected offsite grid voltage and maximum
-load condition, each offsite source and distribution system connection combiniation must be capable of starting and of continuously operating all class 1E equipment within the equipment voltage ratings.
APC has shown, by analysis, that each offsite source and distribution system connection combination has sufficient capability and capacity for starting and continuously operating the class 1E loads within the equipment voltage ratings (Table 1).
Position-2--With the maximum expected offsite grid voltage and minimum load condition, each offsite source and distribution system connection combination must be capable of continuously operating the required class 1E equipment without exceeding the equipment voltage ratings.
The licensee's analysis indicates that the voltage for the 550V and 200V motors will be.less than 1/2% above the maximum allowable value for these. motors. This small of an increase over the 110% rating of the motor will not significantly affect their continuous operation. The voltage for the other class 1E equipment will be within their ratings. Therefore, the voltages will satisfy the requirements as expressed in the above position.
Position 3--Loss of offsite power to either of the redundant class 1E distribution systems due to operation of voltage protection relays, must not occur adven the offsite power source is within expected voltage limits.
Under transient conditions (Table 2), it appears that the minimum voltage comes close to the setpoints for both the degraded grid and loss-of-voltage relays. This is based on transferring the worst case minimum 4160V bus voltage of 75.97%'from the Case A3 analysis 2 to Figure 2 of APC's July 17,1980,6 submittal (which shows the CV-2 less-of-voltage and degraded grid voltage relay curves) with an assumed six-second transient
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time for the start of a' Condensate Pump (noted in Figure.1 of the January ~ 15,'1979,4 submittal).
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This position is satisfied based on APC's conservative analysis which
.shows a transient condition for _ the simultaneous start of all LOCA loads coincident with the start of a Condensate Pump. Loss of offsite power to 6
the class IE distribution system is not expected to occur due to operation of the voltage protection relays. However, it is recommended that the licensee institute plant procedures limiting the start of a Condensate Pump when the voltage on 4160V IE buses fall below 3800V (91%), and the LOCA loads are starting.
Position 4--The NRC letterI requires that test results verify the accuracy of the voltage analyses supplied.
The test procedure and results have been reviewed and found acceptable.
Position'5--No event or condition should result in the simultaneous or consequential loss of both required circuits from the offsite power network to the onsite distribution system (GDC 17).
APC has analyzed the onsite distribution system connections to the of fsite power grid, and datermined that no potential exists for simultaneous or consequential los-of both circuits from the offsite grid.
Position 6--As required by GDC 5, each offsite source shared between units in a multi-unit station must be capable of supplying adequate starting and operating voltage for all required class lE loads with an accident in one unit and an orderly shutdown and cooldown in the remaining units.
Each unit is independently connected to offsite power sources and have some common electrical power interconnections between units at the 600V load centers and 600V motor control centers. APC's analysis considers an accident in Unit 1 (LOCA) and the simultaneous shutdown of Unit 2 has dem-onstrated the adequacy of starting-and operating voltages for all required
-class IE loads. Under these conditions, the analyzed voltages are within the equipment ratings.
6.0 CONCLUSION
S The voltage analyses submitted by the Alabama Power Company for Joseph M. Farley Nuclear Power Station were evaluated in Section 5 of this
' report. It has been determined that:
1.
Voltages within the operating limits of the class lE equipment are supplied for all projected combinations of plant load and normal of fsite power grid conditions; including an accident in one unit and the safe shutdown
'of the other unit.
2.
The test results verified the analysis accuracy.
3.
Justification supporting the applicability of the Unit 2 testing, combined with the prior Unit 1 test 2, for
, verifying the Unit i design is. acceptable.
4.
APC has determined that no potential for either a simultanous or consequential loss of both offsite power sources exists.
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'5.
Loss of offsite power to class IE buses, due to spur-
. ious operation of voltage protection relays, will not i
occur with the offsite grid voltage within its expected limits.
It is recommended that the licensee institute plant procedures limiting the start of 'a Condensate Pump when the voltage on 4160V IE buses fall below 3800V, and the LOCA loads are starting.
7.0 REFERENCES
NRC letter, William Gammill, to All Power Reactor Licensees (Except 1..
Humboldt Bay), " Adequacy of Station Electric Distribution Systems Voltage," August'8, 1979.
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i 2.
APC letter, F. L. Clayton, Jr., to U. S. Nuclear Regulatory Commission, dated December 11, 1979.
3.
APC letter, J. T. Young, to U. S.' Nuclear Regulatory Commission, dated
. November 7, 1977.
4.
-APC letter, F.'L. Clayton, Jr., to U. S. Nuclear Regulatory Commission, dated January 15,~1979.
5.
- APC letter, F. L. Clayton, Jr., to U. S. Nuclear Regulatory Commission, dated May 1, 1980.
- 6. -
APC letter, F. L.' Clayton, Jr., to U.S. Nuclear Regulatory Commission, dated July 17, 1980.
4.
7.
' APC letter, ' F. L. Clayton, Jr., to U.S. Nuclear Regulatory Commission, dated July-30, 1980.
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8.
APC letter, F. L. Clayton,' Jr., to U.S. Nuclear Regulatory Commission,
-dated August 7, 1980.
-9.. APC letter, F. L. Clayton, Jr., to U ". Nuclear Regulatory Commission,
-dated October 7, 1980.
. - 10.. NRC memorandum, P. S. Check, to T. Novak and R. T. Tedesco, " Updated I
t Safety Evaluation, Degraded Grid Voltage Protection.for the Class lE A.C. Power Systems," July 25, 1980.
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' IGU memorandum, P. S. Check, to T. Movack and R. T. Tedesco, " Updated Safety Evaluation, Degraded Grid Voltage Protection for-the Class IE LA.C. Power System," August 13, 1980.
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