ML20010D804
| ML20010D804 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/31/1981 |
| From: | Weber D EG&G, INC. |
| To: | Shemanski P Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6429 EGG-EA-5475, NUDOCS 8108310544 | |
| Download: ML20010D804 (17) | |
Text
{{#Wiki_filter:Of ANie P ftS EGG-EA-5475 FM July 1981 d 'G t ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM q 5 V0LTAGES, OYSTER CREEK NUCLEAR POWER STATION, [ N 4 DOCKET NO. 50-219 } AUG 2 4 $8]> { B; M g->j- .g W' D. A. Weber PRELIMINARY N 30 lesearca anc ~ecanica U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory
~ ? l i & O h V IA f SV": ~ t . 4N:\\ e - c d' e 'Nareane, warmur ~) ,i s .---r-- w a l p aag Cl?
- Now,
.r X5k=rMW7d;W*h;cz &~&:^?iT. W5%. - Y"'W~?" i'. P" -G _a %.-;. E mg_. 3_-ewr~- -~ w, 7 3 %h. %g.'- .ma:aminW p syg l.., i .ta#y cr w ~ t 4 g 3,w g-i w -:* q.(3 p ~- _Dg i 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. A6429 y EGnG,a,n. p 8108310544 810731 POR RES 8108310544 PDR
9 E G n G we.. m. FORM (G&G 398 m. iin, INTERIM REPORT Accession No. Report No. EGG-EA-5475 Contract Program or Project
Title:
Selectei Operating Reactors Issues Program (III) Subject of this Document: Adequacy of Station Electric Distribution System Voltages, Oyster Creek Nuclear Power Station, Docket No. 50-219 Type of Document: Technical Evaluation Report Author (s): } }h }gg@@[C] 8n( TOC'30 001 D. A. Weber Assistance Report Date of Document: July 1981 Responsible NRC Individual and NRC Office or Division: Paul C. Shemanski, Division of Licensing This document wa= prepared primarily for preliminary orinternal use. it has not received full review and approval. Since there may be substantive changes, this document Thould not be considered final. EG&G Idaho, Inc. Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C. Under DOE Contract No. DE-AC07-76f D01570 NRC FIN No. A6429 INTERIM REPORT
0431J h. ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES OYSTER CREEK NUCLEAR POWER STATION Docket No. 50-219 4 July 1981 D. A. Weber i Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc. NRC Researca anc ecanical ~~ N Assistance Report Draft 6-30-81 TAC No. 12766
i ABSTRACT 1 The Nuclear Regulatory Commission has required all licensees to analyze the electric power system at each nuclear station. This review is to deter-mine if the onsite distribution system in conjunction with the offsite power sources has sufficient capacity and capability to automatically start and operate all required safety loads within the equipment voltage ratings. This Technical Evaluation Report reviews the submittals for the Oyster Creek Nuclear Power Station. The onsite distribution system in conjunction with the offsite power sources has, with voltage regulation, sufficient capacity and capability to continuously operate all required safety-related loads within the equipment rated voltage limits in the event of either an anticipated transient or an accident condition. Certain 460 V motor starters and 480 V safety related motors could operate below their minimum allowable voltage and some 440 V motors could be operated in excass of their maximum allowable rating with-out voltage regulation. 4 FOREWORD ' $,' t This report is supplied as part of the " Selected Operating Reactor Issues Prog am (III)" being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing, by 1 i EG&G Idaho, Inc., Reliability and Statistics Branch. f e i i g -*+4 y 9% $~-. ,yy-,-g -iy-wy c.9 yv.vwyy ,-,w9g yp y,,--wA-- y, p ,,9-4 ,yg,, 9+-w,yy .,w9 yw-e,yy-,- 7 ,,.,w-+ y
The U.S. Nuclear Regulatory Comission funded the work under the authorization, B&R 20 19 01 06, FIN No. A6429. y sif 4 l ( L
CONTENTS
1.0 INTRODUCTION
1 2.0 DESIGN BASIS CRITERIA............................................. 2 3.0 SYSTEM DESCRIPTION................................................ 3 4.0 ANALYSIS DESCRIPTION.............................................. 5 4.1 Analysis Conditions.......................................... 5 4.2 Analysis Results............................................. 6 4.3 Analysis Verification........................................ 6 5.0 EVALUATION........................................................ 6
6.0 CONCLUSION
S....................................................... 10
7.0 REFERENCES
Il / FIGURE i. Oystte Creek electrical single-line diagram....................... 4 i TABLES 1. Class lE Equipment Voltage Ratings and 4 Analyzed Worst Case Load Terminal Voltages........................ 7 2. Comparison of Analyzed Voltages and Undervoltage Relay Setpoints...................................... 8 f i e iv
3 ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM VOLTAGES 4 0YSTER CREEK NUCLEAR POWER STATION
1.0 INTRODUCTION
1 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 Desion Criteria (GDC) 17 is being questioned at all nuclear power stations. Th 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 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. The Jersey Central Power and Light Company (JCP&L) responded to this letter on November 1, 1979.2 This submittal, submittals of November 5, 1976,3 April 18, 1977,4 September 25, 1979,5 November 1, 1979,0 August 11, 1980,7 April 30, 1981,8, and the Final Safety Analysis Report (FSAR) complete the information reviewed for the report. Based on the information supplied by JCP&L, this report addresses the ~ l capacity and capability of the onsite distribution system of the Oyster Creek Nuclear Power Station, in conjunction with the offe,ite power system, r N RC Researc1 anc "ec1nica j Assistance Report i
to maintain the voltage for the required class lE equipment within accep-table limits for the worst-case starting and load conditions. 4 2.0 DESIGN BASIS CRITERIA l The positions applied in determining the acceptability of the offsite voltage conditions in supplying power to the class 1E equipment are derived f rom the following: 1. General Design Criterion 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), " Snaring of Structures, Sys-tems, 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 Con-trol," of Appendix A, " General Design Criteria for Nuclear Power Plants," of 10 CFR 50. 4. IEEE Standard 308-1974, " Class lE Power Systems for Nuclear Power Generating Stations." 5. Staff positions as detailed in a letter sent to the licensee, dated August 8, 1979.I h% 2
n 6. ANSI C84.1-1977,~" Voltage Ratings for Electric Power Systems and s Equipment (60 Hz)." Six review positions have been established from the NRC analysis guide-I lines and the above-listed documents. These positions are stated in Section 5.0. 3.0 SYSTEM DESCRIPTION Figure 1 is a sketch of the Oyster Creek single line diagram of the unit electrical distribution system. During normal full power plart operations the Oyster Creek main gener-ator supplies all or. site loads through the single 24/4.16kV Station Auxil-iary Transformer (SAT) which supplies f ur 4160 V buses lA,18, IC, and ID (lC and 10 are safety related). Should tais source of power become unavail-aole the loads on these buses will automatically fast transfer to the Start-up Transformers (ST) A and B (buses lA and 1C will transfer to ST-A and buses 18 and ID to ST-B). Each 34.5/4.16kV ST can be supplied from the 34.5kV offsite distribution system or from the 230kV grid via a 230/34.5kV t rans'former. Voltage regulators installed on the 34.5kV system will main-tain the 4160V bus voltage between 4100V and 4210V when the 230kV. grid is between 214.82kV and 242kV. L The emergency 4160V buses 1C and ID supply power to station loads important to plant safety and vital to safe shutdown under accident conditions. Each bus supplies three 480V unit substations which in turn s 3 1
Ia i* w i.g .o; a w n2? R" E $u ynD i es b A Q- >l g a ~ ,ng
- a..
-4 m
== w -2 = o en 5 L._ ~ N f 50 3F, m,. o } e-, ~ o w r 1 g g, </' ( m e = ,r c f g m 0 h A ed / A [ es 4.< I m eg = w m s-t en ,1 g E k m, g e s / e t t wn 8 ~n* / k _T
/
~N s 3m "-E ~4 = I c S 8 e $i ei sA n if o 3 1 ff'3 e (I - n. ll 3 ? 1, i q E o R m i t Io I ? f' E g
- t. g\\
E-es U }f ^ -e- ,1 A ~~~-1' i> w s g' f j. 53 Ii r: w t "-} a3 s e U3e 2 C 'h> 4 i 00* J E4 4-w n s = 3 fM*O d n E 3 -n', ft a: ] [~A [ M .2. _ -,r ~' I o a e (,JL2 y t m f %e JCw 't d~ A-w N ^ C yt p u 8 7 "- (a L- - - -{ p f gg g g ( 3 i t y Q 3 7s '{ -d 4 \\ w N; \\ JI g = 3 e. a t t,
- i y
44 B A-N g sh f ~ u m "g p \\ g -g H 3* t-f g g \\ c n e N s -- 2 -a a j D 's R 1 w w -2 33C T a E h-O a a re)( mi I a A e-, j 't1 di ' '( a w ~ e g ( 1* 7 _. A [ zo _s R "s w ge k k 3 ) E 24
- S E
so s ? . M. s o ~-' i -J @ en yy n I E.i %a., C .i, n Oyster Creek Nuclear Power Station eletrical distribution 3 Figure 1. system single-line diagcam. 4 -ee-.
7 supply: medium sized electrical loads; 460V motor control centers (MCC's) including the vital MCCs and stepdown traasformers (460/120-208) for light-ing, instrumentation and plant service loads. During normal plant opera-tion the tie breakers between the 4160V switchgear 1C and ID are normally t open and the breakers between the unit substations are racked out. There are three 125V DC systems (DC-A, B, and C) which supply redun-dant DC control power to the switchgear and unit substations in additfor. to other DC loads. Each 125V DC system is supported from its own single 60 cell battery system, and solid state battery chargers or M-G sets. 4.0 ANALYSIS DESCRIPTION 4.1 Ar.alysis Conditions. CP&L has determined by stability analysis that the maximum expected offsite grid voltage is 242kV and the minimum is 214.82.8 i t CP&L has analyzed each offsite souru; to the onsite distribution sys-i tem under extremes of load and offsite voltage conditions, with and without the 34.5kV voltage regulators, to determine the terminal voltages to lE equipment. This report considers the distribution system with and without the voltage regulators. The worst case class IE equipment terminal voltages occur under the following conditions: 1' Maximum voltage occurs when the offsite grid is at the highest analyzed value and the plant is shutdown and operating only minimum loads. 5 i
The minimum steady state voltage occurs when the offsite grid is at its minimum analyzcJ value and all normal and LOCA loads are running as well as the reactor feed pumps. The minimum transient voltage occurs as in the minimum voltage condi-tions above accept for the start of a reactor feed pump. The longest time required for any large motor to accelerate to running speed, with rated voltage at its terminals, is seven seconds. 4.2 Analysis Result. Table I shows the projected worst case class lE equipment terminal voltages without voltage regulation. Table 2 shows a comparison of the undervoltage relay set points with the analyzed voltages. 4.3 Analysis Verification. in order to verify their cunputer 0 analysis, CP&L conducted a test on July 23, 1980 at the Oyster Creek Flant. Using the existing grid voltage at the time of the test, a computer run was made to predict voltage levels at the 4160, 480, and 120V levels. These predicted values were then compared to actual readings takta at the Oyster Creek Station. Bus and transformer loading conditions during the. test ranged from 39% to 100%.8 I 5.0 EVALUATION Six review positions have been established from the NRC analysis guide-I lines and the documents listed in Section 2.0 of this report. Each review i i 6 )
e TABLE 1. CLASS lE EQUIPMENT VOLTAGE RATINGS AND ANALYZED WORST CASE TERMINAL V0LTAGES WITHOUT VOLTAGE REGULATION (% of nominal voltage) ~ _ Maximum Minimt$" a Analyzed Equipment Condition Rated Analyzed Rated 5teady State Transient 80 89 4000V Motors Start Operate 110 110 90 91.6 85 78 480V Motors Start Operate 110 105 86.6c g 460V ' Motors Pickup 85 83 Operate 110 110 86.6c 87.5 77 85 440V Motors Start Operate 110 115 86.6c 90.5 5 460V Starters Pickup 85.7 85 85.7 60 Dropout Operate 110 110 90 87.5 Other Equipment Rated 110 <110 90 100.8 >99 Il5V a. Maximum values based on Table 1 and 2 of the November 1, 1979 submit-tal,6 adjusted for a maximum grid value of 242kV and no allowance for voltage drop between load centers and motor control ceiiters or the motor f eeder cables, i b. Minimum values based on Table 2 and 3 of the August 11, 1980 submittal 7 I adjusted for the minimum analyzed grid voltage of 214.82kV (3671V at the l 4160V IE buses). l Worst case safety related motors have a 1.15 service factor.9 c. l i e 7 (
_ _ - - =. TABLE 2. COMPARIS0N OF ANALYZED VOLTAGES AND UNDERVOLTAGE RELAY SETPOINTS (without voltage regulation) Minimum Analy ed Relay Setpoint Lccation/ Relays Voltage Time Voltage (Toleranco) Time 4160V busa 1 i Degraded grid 3671V cont. 3671V + 1% 10 sec + 0.1% Loss of grid 3594 7 sec 2864V - 3 sec 0.5% l a. Licensee has determined by analysis the minimum bus voltages with the offsite grid at the riinimum expected voltage and the worst case plant and class lE loads. 4 position is stated below followed by an evaluation of the licensee submittals. i Position 1--With the minimum expected offsite grid voltage and maximum load condition, each offsite source and distribution system connection combination must be capable of starting and of continuously opera'.ing all class IE equipment within the equipment voltage ratings. This position is not satisfied without voltage regulation as certain i 460V motor starters and the 480V motors would be required to operate a voltage below the minimum ra.ings (Table 1). Position 2,--With the maximum expected offsite grid.C;tage and minimum load condition, each offsite source and distribution system connection t combination must be capable of continuously operating the required class lE equipment without exceeding the equipment voltage ratings. 8
t o r This position is not satisfied without voltage regulation as some of i l the 440V motors would have voltage in excess of maximum rating. Maximum voltages ori equipment witn ll5V nominal rating not provided. j Position 3--Loss of offsite power to either of the redundant class lE distribution systems, due to operation of voltage protect;on relays, must l not occur when the offsite power source is within expected voltage limits. i j This position is not satisfied as the second level undervoltage relays I could operate if the grid is at or slightly above its minimum analayzed value (Table 2). I Position 4--The NRC -letter requires that test results verify'the j accuracy of the voltage analyses supplied. r, A review of JCP&L test procedure and results indicate that the analysis is satisfactory. The test result shows that the largest difference between i the measured and computed values is +1%. 1 l Position 5--No event or condition should result in the simultaneous or l consequential loss of both required circuits from the offsite power network to the onsite distribution system (GDC 17). I JCP&L has analyzed the Oyster Creek Nuclear Power Station connections to the offsite power grid, and have determined that no potential exists for simultaneous or consequential loss of both circuits from the offsite grid. 9 m
Position 6--As required by GDC 5, each offsite source shared between units in a multi-unit station must be capable of supplying adequate start-ing and operating voltage for all required class lE loads with an accident j in one unit and an orderly shutdown and cooldown in the remaining units. l i j This applies to multi-unit plants. It does not apply to the Oyster Creek single-unit station. l i )
6.0 CONCLUSION
S 1, The voltage analyses submitted by JCP&L for the Oyster Creek Nuclear Power Station were evaluated in Section 5.0 of this report. It was found that: b j 1. With voltage regulation, voltages within the operating limits of the class lE equipment are supplied for all projected combinations of plant load and offsite power grid conditions. Without regula-l tion, voltages to certain class lE loads are unsatisfactory. 2. The test used to verify the analysis shows the analyses to be an J accurate representation of the worst case conditions analyzed. 3. JCP&L has determined that no potential for either a simultanous i or consequential loss of both offsite power sources exists. 4 i 10 l L.,,---.--._.----,.- i
r 4 Loss of offsite power to class lE buses, due to spurious operation of voltage protection relays, should not occur with the offsite grid voltage within its expected limits and the 34.5 voltage regulators in operation. Without the regulators, spurious trip-ping could occur. 4 As a result of their original analysis JCP&L has installed voltage regulators on the 34.5kV grid, which maintain the 4160V bus between 4100V and 4210V for extremes of normal offsite grid voltages. These voltage regu-lators will maintain all safety related equipment within their operating limits and prevent spurious separation of class lE buses from the offsite power sources. However, credit for these regulators is dependent upon inclusion of limiting condition of operation requirements in the plcnt technical specifications. 7.0 REFERENCE 5 1. NRC letter, William Gammill, to All Power Reactor Licensees (Except Humboldt Bay), " Adequacy of Station Electric Distribution Systems Voltage," August 8, 1979. 2. JCP&L letter, I. R. Finfrock, Jr. to Director of Nuclear Reactor Regulation November 1, 1979. 3. JCP&L letter, I. R. Finfrock to George Lear, Chief, Divisior, of j l Operating Reactor, Branch No. 3, Nuclear Regulatory Commission, November 5, 1976. 4. JCP&L letter, I. R. Finfrock to George Lear, Chief Division of-Operat-ing Reactor, Branch No. 3, Nuclear Regulatory Commission, April 18, 1977. j 5. JCP&L letter, I. R. Finfrock to Director of Nuclear Reactor Regulation, September 25, 1979. 6. JCP&L letter, I. R. Finfrock to Director of Nuclear Reactor Regulation, November 1, 1979. 11 l
n 7. JCP&L letter, I. R. Finfrock to Director of Nuclear Reactor Regulation, August 11, 1980. 8. JCP&L letter, I. R. Finfrock to Director of Nuclear Reactor Regulation, April 30, 1981. 9. Telcon, P. Wells, JCP&L, D. Weber, EG&G Idaho, Inc., May 29, 1981. e 12 )}}