ML20003F954
| ML20003F954 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 04/15/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20003F953 | List: |
| References | |
| NUDOCS 8104240581 | |
| Download: ML20003F954 (4) | |
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UNITED STATES Enclosure l NUCLEAR REGULATORY COMMISSION O$
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WASHINGTON. D. C. 20655
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k SAFETY EVALUATION JAMES A. FITZPATRICK NUCLEAR POWER STATION DOCKET NO. 50-333 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES INTRODUCTION AND SUM 4ARY The Power Authority of the State of New York (PASNY) was requested by NRC letter dated August 8,1979 to review the electric power system at James A. Fit: patrick Nuclear Pcwer Station. The review was to consist of:
(a) Determining analytically the capacity and capability of the offsite power system and the onsite distribution system to automatically start as well'as operate all required safety loads within their re-quired voltage ratings in the event of (1) an anticipated transient, or (2) an accident (such as LOCA) without manual shedding of any electric loads.
(b) Deternining if there are any events or conditions which could result in simultaneous or, consequential loss of both required circuits from the offsite network to the onsite electric distribution system and i
thus violating the requirements of GDC 17.
l The August 8,1979 letter included staff quidelines for performing the required l
l voltage analysis and the licensee was further required to perform a test in l
order to verify the validity of the analytical results. PANSY responded by letters dated September 7,1979; which referred to previous submittals of October 18, 1976, December 31. 1976, July 13, 1977 and October 18, 1977 regard-ing operation of safety-related equipment under degraded grid condition; and 8104240 $$l
. July 1, 1980. A detailed review and technical evaluation of the submittal was performed by EG&G under contract to NRC, and with general supervision by NRC staff. This work was reported in EG&G's Technical Evaluation Report (TER),
" Adequacy of Station Electric Distribution System Voltages, James A. Fitzpatrick Nuclear Power Station" dated January 1981 (attached). We have reviewed these reports and concur in the conclusions that after (1) completion of proposed i
modification to change transformer taps on the 600v emergency load center trans-forner and (2) satisfactory results are obtained from the voltage analysis verification testing the offsite power system and onsite: distribution system will be capable of providing acceptable voltages at the terminals of the Class IE equipment for the worst case station electric load and grid voltages.
EVALUATION CRITERIA The criteria used by EG&G in this technical evaluation of the analysis includes GDC 5 (" Sharing of Structures, Systems, and Components"1, GDC 13 ("Instrumenta-tion and Control"), and GDC 17 (" Electric Power Systems") of Appendix A to 10 CFR 50; IEEE Standard 308-1974 (" Class lE Power Systems for Nuclear Power Generating Stations"l; ANSI C84.1-1877 ("Vo.he Ratings for Electric Power Systems and Equipment - 60 Ha"); and the staff position and guidelines in the NRC letter to PASNY dated August 8,1979.
ANALYSIS and TEST FEATURES The analysis was performed using the reserve station service transformers with the maximum and minimum switchyard (grid) voltage (122 Ky and 115 Kv respectively.
It has been verified that one Reserve Station Service Transformer can not physically be used to supply power to both safety trains. PASNY will perform a test at the next scheduled plant outage to verify the voltage analysis. We require the test to meet the following criteria and the results to be submitted for our review.
. a) Loading the station distribution buses, including all Class'lE buses down to the 120/208v level, to at least 30%;
b) Recording the existing grid and Class lE bus voltages and bus loading down to the 120/208 volt level at steady state conditions and during the starting of both a large Class l$ and non-Class lE motor (not concurrently);
(Note)
To minimize the number of instrumented locations (recorders) during the motor starting transient tests, the bus voltages and loading need only be recorded on that string of buses which previously showed the lowest analyzed voltages.
c) Using the analytical techniques and assumptions of the previous voltage analyses and the measured existing grid voltage and bus loading condi-tions recorded during conduct of test, calculate a new set of voltages for all Class lE buses down to the 120/208 volt level.
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d) Compare the analytically derived voltage values against the test results.
With good correlation between the analytical results and test results, the test verification requirement will be met. That is, the validity of the i
mathematical model used in performance of the analysis will have been established.
In general the test results should be within : 3% of the analytical results; however, the diffe ence between the two when subtracted from or added to should never provide values that would allow operation of the Class lE equipant outside of rated voltage ranges.
. If the results of the planned test prove the analysis to be accurate, PASNY proposes to lower the taps on the 600v emergency load center transformers to 3,950/600v tap to optomize emergency bus voltage profiles. With the transformers normally loaded, at the minimum bus (grid) voltage analyzed, this tap setting would provide a bus voltage of 566v (94.3%) on th'e 600 volt buses.
CONCLUSION We have reviewed the EG&G Technical Evaluation Report and concur in the findings that:
1.
PASNY has provided a voltage analysis to demonstrate that after the proposed transformer tap changes are accomplished the Class lE equip-ment terminal voltages will remain within acceptable operating limits for the postulated worst case conditions.
2.
The test proposed by PASNY if performed under our guidelines contained in this report will provide verification of the analyses.
We therefore find the James A. Fitzpatrick design to be acceptable with respect to the adequacy of station electric distribution system voltages subject to the transformer tap changes and verification testing required above. We shall address the verification testing in a supplement to this report.
Dated: April 15,1981
i Enciosure 2 EGG-EA-5340 January 1981 TECHNICAL EVALUATION REPORT, ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES, JAMES A. FITZPATRICK NUCLEAR POWER STATION, DOCKET NO. 50-333 D. A. 'Jeber U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory
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This is art Informal report intended for use as a preliminary or working document Prepared for the U.S. Nuclear Regulatory Counission Under DOE Contract No. DE-AC07-76ID01570 FL4 No. A6429 0
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Il EGnG 4,4 sonu seso-sea Ri ev 11 Tm INTERIM REPORT Accession No.
Report No. ECG-EA-5340 Contract Program or Projec'
Title:
Electrical, Instrumentation and Control System Support Subject of this Document:
Adequacy of Station Electric Distribution System Voltages, James A. FitzPatrick Nuclear Power Station Type of Document:
Technical Evaluation Report Author (s):
D. A. '4eber Date of Document:
January 1981 Responsible NRC individual and NRC Office or Division:
Paul C. Shemanski, Division of Licensing l
t This document was prepared pnmarily for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes, this document should not be considsred final.
EG&G Idaho, Inc.
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Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 761D01570 NRC FIN No. A6429 l
INTEMIM REPORT 1
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ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES JAMES A. FITZPATRICK NUCLEAR POWER STATION Docket No. 50-333 January 1981 D. A. Weber Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.
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I CONTENTS 1.0 LNTRODUCTION......................................................
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2.0 D ES IGN B AS IS CRITERIA.............................................
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3.0 SY STEM D ES CRI PTION................................................
2 1
4.0 ANALYSIS DESCRIPTION..............................................
2 4.1 De s i gn Chan g e s...............................................
2 4.2 Analysis Conditions..........................................
4 l
4.3 Ana ly s i s Re s u l t s.............................................
5 4.4 Analysis verification........................................
5 5.0 EVALUATION.........................................................
5
6.0 CONCLUSION
S.......................................................
7
7.0 REFERENCES
7 l
FIGURE l
1.
James A. FitzPatrick electrical single-line diagraa...............
3 TABLES
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1.
Class 1E Equipment Voltage Ratings and Analyzed Worst Case Load Terminal Voltagea 4
2.
Comparison of Analyzed Voltages and Undervoltage Relay Setpoints......................................
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1 ADEQUACY OF STATION ELECTRIC DISTRI3UTION SYSTEM VOLTAGES JAMES A. FITZPATRICK NUCLEAR POWER STATION
1.0 INTRODUCTION
An event at the Arkansas Nuclear One station on September 16, 1978 is described in NEC IE Information Notice No. 79-04.
As c result of this event, station conformance to General Design Criteria (GDC) 17 is being questioned at all nuclear power stations. The NRC, in the generic letter of August 8,1979, " Adequacy of Station Electric Distribution Systems Volt-ages," I required each licensee to confirm, by analysis, the adequacy of the voltage at the class 1E 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 1E loads.
The Power Authority of the State of New York (PASNT) submitted a letter dated September 7, 1979,2 which referred to previous submittals of October 18, 1976,3 December 31, 1976,4 July 13,1977,5 and October 17, 1977,6 regarding operation of safety-related equipment under degraded grid conditions. These submittals, the Final Safety Analysis Report (FSAR) and a submittal of July 1,1980,7 (response to a request for additional information), complete the information reviewed for this report.
Based on the information supplied by PASNY, this report addresses the capacity and capability of the onsite distribution system of the James A. FitzPatrick Nuclear Power Station (JAFNPS), in conjunction with the offsite power system, to maintain the voltage for the required class 1E 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 offsite voltage conditions *n supplying power to the class IE equipment are derived i
I from the following:
1.
General Design C -iterion 17 (GDC 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.
3.
General Design criterion 13 (GDC 13), " Instrumentation and Control," of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50.
4.
IEEE Standard 308-1974, " Class 1E Power Systems for Nuclear Power Generating Stations."
1
s 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-linesl and the above-listed documents. These positions are stated in Section 5.0.
3.0 SYSTEM DESCRIPTION Figure 1 of this report is a simplified sketch of the unit single-line diagram.
The class 1E distribution system supplies offsite power from two reserve station service transformers, T2 and T3, connected to the 115kV switchyard and one normal station service transformer, T4, connected to the 345kV switchyard. During plant operations, the safaty-related and nonsafety-related buses are supplied by transformer T4.
t.utomatic fast transfer from T4 to T2 and T3 is initiated by generator protective relays, reactor trip, or when the 4160V bus voltage falls below a predetermined value, independent of generator or reactor trip.
The class 1E distribution system consists of two redundant and inde--
pendent trains. Transformer T2 supplies one erzin and T3 supplies the other via an independent 4160V normal buses. Each train is capable of supplying the required emergency loads.
Each 4160V emergency bus supplies power to the 4kV motors, 600V load centers and motor control centers (MCCs), 575V motors and loads, and the 120V A.C. distribution and lighting transformer. The breaker control cir-cuits for the 4160V switchgear and the 600V load centers are supplied by the station bacteries and are independenc of grid voltage, The MCC control circuits recieve their control power from individual control power transformers.
PASNY has verified that one reserve service.tation transformer cannot supply loads to both saferv tr2ina, f
PASNY supplied the equipment operating ranges identified in Table 1.3 7 9
4.0 ANALYSIS DESCRIPTION 4.1 Design / Operation Changes. The voltages shown on Table 1 are based on the tollowing licensee proposed changes:
Sk PASNY proposes to lower the taps on the 600V emergency load center transformers to the 3,950/600V tap to optimize emergency bus voltage pro-files. With the transformers normally loaded, the voltage on the 600V emergency load center buses would be 580V (96.6%) and 566 V (94.3%) with a 115kV bus voltage of 117kV and 115c?, respectively.
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James A. Fi: Patrick unit single-line diagram.
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TABLE 1 CLASS 1E EQUIPMENT VOLTAGE RATINGS AND ANALYZED WORST CASE TERMINAL VOLTAGES
(% of nominal voltage)
Maximum
- Minimum" Analyzed Equipment Condition Rated Analyzed Rated Steady State Transient 78535~
4000V Motors Start 75 Operate 110 105.8 ~
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/ 93.32 575V Motors Start 80 80.78
- j operate 110 107.3 90
> 90.08 600V Starters Pickup 85 32C Dropout 70 82 Operate 110 107.5 90 91 Other Equipmengb a.
115kV nominal: maximum 106.1% and analyzed minimum 100%.
b.
"All safety-related electrical, instrumentation, and control equipment required for safe shutdown will o of 90 to 110 percent of nominal."gerate properly within a voltage range c.
All class 1E motors in operation.
4.2 Analysis Conditions. PASNY has determined by transient stability f
analysis that the maximum expected 115kV offsite grid voltage is 122kV and tne minimum is 116kV; however, for conservatism, 115kV minimum vol:: age was used as the low grid voltage in the PASNY analysis.
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PASNY 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 class IE equipment terminal voltages occur under the following conditions:
1.
The maximum e l "g= occurs when the offsite 115kV grid is acTaaximum expected value and no load on the j
reserve station and load center transformers.
l 2.
The minimum voltage-occurs-when the offsite 115kV grid is at its minimum expected v lue and with a full load on the reserve station and load center transformers.
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The worst case transient voltages occur when starting one 3,000 hp condensate booster pump when the offsite grid is at its minimum value and with a full load on the reserve station and load center transformers.
4.3 Analysis Results. Table i shows the projected worst case class 1E equipment terminal voltages based on the proposed 600V load center trans-forner tap settings. Table 2 shows a comparison of the analyzed voltages with the undervoltage relay setpoints.
4.4 Analysis Verification. PASNY has indicated, in their submittal of July 1, 1980/, that ene voltage calculations performed for the JAFNFP will be verified by the field test described below. The' test will be scheduled during the late 1980 planned outage and the test results will be submitted within 90 days from the date of plant startup after the outage.
Cnart recceders and other analog / digital instruments will be installed in the switchyard on the 345tv and 115kV systems, on the 4160V IE and non-1E buses (the 1E buses will be 10500 and 10600), and on the 600V emergency load centers and motor control center. The exact location of the test instruments on the 6007 system has not yet been determined. However, all 600V 1E buses will be monitored during the test.
The data will be gathered under plant operating conditions, including startup af*,er refueling, for an extended period of time. The loading on the 1E buses will vary with plant operating conditions; however, the data used to verify the analysis will be for bus losds greater than 30%.
The measured bus voltage and loads will be correlated with the measured i
l offsite grid voltage to establish the actual distributiou system impedance I
values. These values will then be compared with the impedance values used in the calculations to verify the accuracy of the analysis is within accept-able colerances.
5.0 EVALUATION Six review positions have been established from the NRC analysis guide-linesl and the documents listed in Section 2.0 of this report. Each review position is stated below followed by an evaluation of the licensee s ubmittals. The evaluations are based on completion of changes described l
in Section 4.1.
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 cantinuously operating all class 1E equipment within the equipment voltage ratings.
l PASNY has shown, by analysis, that the offsite source and distribution l
system connection combiniation has sufficient capability and capacity for starting and continuously operating the class 1E loads within the equipment voltage ratings (Table 1).
l 5
u 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 Degraded grid 90.5 continuous 89.5 10 see Loss of grid 80.9b 71.5/
2.5 see c
a.
Licensee has determined by analysis the minimum bus voltages with the offsite grid at the minimum expected voltage and the worst case plant and class IE loads.
b.
Calculated from Figure 2A and 25 of Reference 7 and Figure 2 of Refer-ence 3.
It is the transie'nt voltage due to the start of a condensate booster pump under full load conditions and minimum grid voltage.
c.
Transient recovery time not provided but PASNY expects it to be less than 10 sec.8 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.
PASNY has shown, by analysis, that the voltage ratings of the class 1E equipment will not be exceeoud.
Position 3--Loss of offsite power to either of the redundant class 1E distribution systems due to operation of voltage protection relays, must i
not occur when the offsite power source is within expected voltage limits.
As shown in Table 2, voltage relays will not causs loss of clasa 1E t
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distribution systems when the offsite grid voltage is within expected volt-l age limits.
Position 4--The NRC letterl requires that test results verify the accuracy of the voltage analyses supplied.
PASNY states that they will supply test results within 90 days from the date of plant startup after the late 1980 outage. The proposed test has been described in Section 4.4 of this report and is 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 discribution system (GDC 17).
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4 PASNY has analysed the onsite connections to the offsite power grid, and determined that ac potential exists for simultaneous or consequential loss of both circuits from the offsite grid.
Position 6--Aa 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.
This applies to suici-unit plants. It does not apply to the James A. FitzPatrick single-unit station.
6.0 CONCLUSION
S Tb* voltage analyses sulmitted by PASNY for the James A. Fit: Patrick Nuc rcr Power Station were evaluated in Section 5.0 of this report. Upon the. completion of changes described in Section 4.1, it was found that:
1.
Voltages within the operating limits of the class IE equipment are supplied for all projected combinations of plant load and offsite power grid conditions.
2.
The proposed cast will verify the analysis accuracy.
3.
P ASNY has determined that no potential for either a simultanous or consequential loss of both offsite power sources exists.
4.
Loss of offsite power to class IE buses, due to spur-ious operation of voltage protection relays, will not occur with the offsite grid voltage within its expected limits.
7.0 REFERENCES
1.
NRC letter, William Gammill, to All Power Reactor Licensees (Excape Humboldt Bay), "Adeqaacy of Station Electric Di e tribution Systems Voltage," August 8, 1979.
2.
PASNY letter, Paul J, Early, to Director of Nuclear Regulation, dated September 7, 1979.
3.
PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated j
Oc tober 18, 1976.
4.
PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated December 31, 1976.
5.
PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated July 13, 1977.
6.
PASNY letter, G. T. Berry, to Director of Nuclear Regulation, dated Oc tober 17, 1977.
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PASNY letter' J* P*
rector f Nuclear Regulation, dated July 1, 1980 8.
Telecon, D. A. Weber' EG&G Idah,
., S. Shultz, PASNY, September 12, 1980.
APR 171981 1
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