ML20009E670
| ML20009E670 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/24/1981 |
| From: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Clark R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 908A, NUDOCS 8107280349 | |
| Download: ML20009E670 (12) | |
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g: % g g July 24, 1981 H.H.LEAMBt!MG Nc am s At nu Mr. Harold R. Denton, Director Serial No.
Office of Nuclear Reactor Regulation PSE&C/EVF/KSB Attn: Mr. Robert A. Clark, Chief Docket Nos. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing U.S. Nuclear Regulatory Commission License Nos. IPF-4 Washington, D.C. 20555 NPF-7 7 ear Mr. Denton:
GENERATOR BREAKER ADDITION AND GENERAL DESIGN CRITERIA 17 ANALYSIS NORTH ANNA UNIT NOS. 1 AND 2 In our letter to you dated September 24, 1980, Serial No. 725A, we discussed the installation of generator breakers for North Anna Units 1 and 2.
We have installed a generator breaker on Unit 1 and are presently analyzing the edequacy of this single installed breaker in providing a permanent solution to the General Design Criteria 17 (GDC-17) concern at North Anna. A one line diagram showing the present situation at North Anna is attached.
With this breaker in service, Unit I start-ups will be accomplished with the Normal Station Service buses being fed from the Normal Station Service transformers (back-fed from the 500 kv switchyard) rather than from the Reserve Station Service transfc~ners. For the majority of Unit 1 trips, Unit I will continue to have its Normal Station Service beses fed from its Normal Station Service transformers.
This arrangement reduces the probability of combined loading from both Unit 1 and 2 normal and emergency buses on the Reserve Station Service transformers.
I Our analyses to determine the adequacy of the installed generator breaker are being conducted in reference to our interpretation of item 2 of the
" Guidelines for Voltage Drop Calculations" which was attached to thc NRC letter dated August 8, 1979, entitled " Adequacy of Station Electrical Distribution System Voltages." Our interpretation is based on a May 20, 1981 telephone conference with your Mr. L. G. Engle and is as follows:
In the analyses of voltage conditions available from the Reserve Station Service System, we are assuming that the worst case would be for Unit 2 to have all of its loads on the reserva, while Unit I has its SI activated safety loads and intake structure loads only on the reserve. We are able 8107280349 810724 0
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ViaorwsA Et,zcTa:C AND Powra COMPANY TO Mr. Harold R. Denton Page 2 to make this assumption on the basis that Unit 1 now has a generator breaker which provides the capability of tripping the unit without transferring loads to the reserve system. We feel that the " accident" or the "unticipated transient in the unit being analyzed" discussed in item 2 of the reference, does not include the occurrences that would cause Unit 1 to transfer loads to reserve at the same time that Unit 2 is fully loaded from the reserves.
The scope of our ongoing analyses includes all guidelines and recuirements set forth in the August 8, 1979 letter previously mentioned, and those mentioned in the June 25, 1980 letter that included a " Request for Additional Information Regarding the Adequacy of Station Electric Distribution System Voltages". Also included in the analyses will be those points which were discussed in an April 2, 1981, telephone corference with your Mr. L. G. Engle and Mr. A. Udy of EG&G.
These analyses will be completed and results forwarded to you within six months.
l We are pres
., assembling technical information concerning the generator breaker installem on Unit 1.
This information will cover mechanical, electrical and operating characteristics of the breaker and will be forwarded for your review within 60 days.
l The installation of the generator breeker on Unit 1 creates an additional independent source of offsite power from the transmission network to the onsite power distribution system, analogous to the Reserve Si:.aion bervice system, whlch is not dependent on the mode of operation of the Unit 1 generator.
In addition, the Unit 2 Normal Station Service system can be considered an additional independent source of offsite power from the transmission network to the onsite power discribution system. This source, however, is dependent on the mode of operation un the Unit 2 generator.
To establish two independent offsite power sources to each emergency bus, nomal to emergency bus ties will M utilized on each unit. Presently, the Unit 1 ties have been installed and are in service.
These ties consist of Bus 1B to Bus 1H and Bus 2B to Bus 1J ties.
It is our intention to install the Unit 2 ties during the next scheduled Unit 2 refueling outage (Spring 1982). The Unit 2 tiu will consist of Bus 2C to Bus 2H and Bus 1A to Bus 2J ties. All of the normal to emergency bus ties have a normally open breaker at each bus.
In conjunction with this modification, the administrative ties between buses lH and 1J have been removed.
The administrative ties between buses 2H and 2J will be removed during installation of the Unit 2 normal to emergency bus ties.
The bus ties will operate as follows:
On either degraded voltage or loss of voltage, an emergency bus will ansfer from its nomally connecteo Reserve Station Service transformer s the assigned Normal Station Service bus, provided that bus is availab'.
svoltage present) and electrically acceptable (no faults, etc.).
This
VinoixA ELECTEIC AND PowEn COMPANY TO Mr. Harold R. Denton Page 3 transfer will be initiated and completed during the interval between the deisel generator start signal (degraded voltage, loss of voltage) and its designed closing time to the emergency bus.
If this transfer is not completed in this interval, the transfer will be aborted and the diesel generator will load to the emergency bus as designed.
A preliminary copy of our proposed changes to the Technical Specifications for Unit 1 is attached for your review. While these changes are not required, their implementation would more accurately reflect the installed system.
Please advise if further information is required.
Very truly youps, li J
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. Leasburg Vice Presioent - Nuclear Operations l
Attachments l
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cc:
Mr. J. P. O'Reilly, Director Office of Inspection and Enforcement Region II U.S. Nuclear Regulatory Commission Washington, D.C. 20555 brc/0154/3
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3/4.8 ELECTRICAL POWER SYSTEMS 3/4.8.1 A.C. SOURCES OPERATING l
l LIMITING CONDITION FOR OPERATION 3.8.1.1 As a minimum, the following A.C. electrical power sources shall be OPERABLE:
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Two separate and independent diesel generators:
1.
Each with a separate day tank containing a minimum of 750
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gallons of fuel, and 2.
A fuel storage system containing a minimum of 45,000 l
gallons of fuel, and 3.
A separate fuel transfer pump.
APPLICABILITY: MODES 1, 2, 3 and 4.
ACTION:
kr tack emege.ncy but a.
With either an offsite circuit or diesel generator of the above required A.C. electrical power sources inoperable, demonstrate the OPERABILITY of the remaining A.C. sources by performing Surveillance Requirements 4.8.1.1.1.a and 4.8.1.1.2.a.4 within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter;Frestore at "E
least'two offsite circuits and* ewe diesel generatory to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
b.
With one offsite circuit and one diesel generator of the above required A.C. electricai power sources inoperable, demonstrate the OPERABILITY of the remaining A.C. sources by performing Surveillance Requirements 4.8.1.1.1.a and 4.8.1.1.2.a.4 within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter;* restore at least one of the inoperable sources to OPERABLE status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hour3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />sWEestore. at gg least'4wer offsite circuit $ and *4wo diesel generator $ to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the time of initial loss oc be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
NORTH ANNA - UNIT 1 3/4 8-1 l
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3.8.l. l a. At least two physically independent circuits between the offsite transmission network and the onsite Class IE distribution system with a minimum of one circuit feeding 4kv Emergency Bus IH and one circuit feeding 4ky Emergency Bus lJ. and
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ELECTRICAL POWER SYSTEMS ACTION (Continued):
for one emergency bus T
c.
With two cf th above required offsite A.C. circuits inoperable, demonstrate the OPERABILITY of two diesel generators by performing Surveillance Requirment 4.8.1.1.2.a.4 within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter, unless the diesel generators are already operating;* restore at least one of the inoperable offsite sources to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.Jith only one offsite source restered.g estore at least ** offsite circuiti r
to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from time of initial loss or be in at least HOT STANOBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
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Ont With two of the above required [ diesel generators inoperable J d.
deanstrate the OPERABILITY of %e offsite A.C. circuiti by performing Surveillance Requirment 4.8.1.1.1.a within one hour and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter; restore at least one of the inoperable diesel generators to OPERABLE status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and l
i in COLD SHUTOOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Restore at least two diesel generators to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from time of initial loss or be in least HOT STANOBY within the l
next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
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SURVEILLANCE REQUIREMENTS 4.8.1.1.1 Each of the above required physically independent circuits between the offsite transmission network and the onsite Class 1E distribution syst e shall be:
a.
' Determined OPERABLE at least once per 7 days by verifying correct breaker aligraent indicating power availability.
l 4.8.1.1.2 Each diesel generator shall be dronstrated CPERABLE:
a.
At least once per 31 days on a STAGGERED TEST 8 ASIS by:
1.
Verifying the fuel level in the day tank.
2.
Verifying the fuel level in the fuel storage tank.
10RTH ANNA - UNIT I 3/4 S-2
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/ddd B ELECTRICAL POWER SYSTEM _S SURVEILLANCE REQUIREMENTS (Continued) 3.
Verifying the fu:1 transfer pump can be started and transfers fuel from the storage system to the day tank.
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4.
Verifying the diesel starts from ambient condition and accel: rates to at least 900 rpm in 1 10 seconds, f
S.
Verifying the generator is synchronized, loaded to 1 375 1
kw, and operates for 1 60 minutes, and 6.
Verifying the diesel generator is aligned to provide standby power to the associated emergency busses.
b.
At least once per 92 days by verifying that a sample of diesel fuel from the fuel storage tank is within the acceptable I
limits specified in Table 1 of ASTM D975-74 when checked for viscosity, water and sediment.
c.
At least once per 18 months during shutdown by:
1.
Subjecting the diesel to an inspection in accordance with procedures prepared in conjunction with its manufacturer's reconnendations for this class of standby service, 2.
Verifying the generator capability to reject & load of 1 610 kw without tripping, 3.
Si.el:t' ; : 10:: Of ef' it p:=r ' conjunetter "ith :
- ty 'nfection t :t :f;n:1, :nd:
SEE KtTMNED PAGE
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b)
Verifying the diesel starts from ambient condition on the auto-start signal, energizes the emergency busses with pennanently connected loads, energizes the auto-connected emergency loads through the timers and operates for 1 5 minutes while its generator is loaded with the emergency loads.
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NORTH ANNA - UNIT 1 3/4 8-3
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Simulating a loss of the reserve station serv *rc system in conjunction with a safety injection test signal to be followed by simulating the loss of the normal station service system, and:
a) Verifying the sequence of emergency busses separating from the reserve station service system, connecting to the normal station service system, separating from the normal station service system, and load shedding from emergency busses.
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ELECTRICAL POWER SYSTEMS 3/4.8.2 ONSITE POWER DISTRIBUTION SYSTEMS A.C. DISTRIBUTION - OPERATING LIMITING CONDITION FGR OPERATION 3.8.2.1 The following A.C. electrical busses shall be OPERABLE and energized with tie breakers open between redundant busses:
b nu e.xisu ng 4160 volt Emergency Bus i 1H 4160 volt Emergency Bus i 1J 480 volt Emergency Bus # 1H,1H1 480 volt Emergency Bus # 1J. 1J1 120 volt A.C. Vital Bus # 1-I 120 volt A.C. Vital Bus i 1-II i
120 volt A.C. Vital Bus i 1-III 120 volt A.C. Vital Bus # 1-IV APPLICABILITY: MODES 1, 2, 3 and 4.
ACTION:
With less than the above complement of A.C. busses OPERABLE, restore the inoperable bus to OPERABLE status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVEILLANCE REQUIREMENTS 4.8.2.1 The specified A.C. busses shall be determined OPERABLE with tie breakers open between redundant busses +at least once per 7 days by verifying correct breaker alignment and indicated power availability.
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3/4.8 ELECTRICAL POWER SYSTEMS BASES 3/4.8.1 and 3/4.8.2 A.C. and 0.C. POWER SOURCES AND DIS? IBUTION The OPERABILITY of the A.C. and 0.C power sources and associated distribution systems during operation ensures that sufficient power will be available t5 supply the safety related equipment required for 1) the safe shutdown of the facility and 2) the mitigation and control of accident conditions within the facility. The minimum specified indepen-dent and redundant A.C. and 0.C. power sources and distributien systems satisfy the requirements of General Design Criteria 17 of Appendix "A" SEE A'TTACHED PAGE The ACTION requirements specified for the levels of degradation of the power sources provide restriction upon continued facility operatinn comensurate with the level of degradation. The OPERABILITY of the power sources are consistent with the initial condition assumptions of the accident analyses and are based upon maintaining at least one of each of the onsite A.C. and 0.C. power sources and associated distri-bution systems OPERABLE during accident conditions coincident with an
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assumed loss of offsite power and single failure of the other onsite A.C. source.
Yhe OPERABILITY of the minimum specified A.C. and 0.C. power sources and associated distribution systems during shutdown and re-fueling ensures tnat 1) the facility can be maintained in the shutdown or refueling condition for extended time periods and 2) sufficient instrumentation and control capability is available for monitoring and maintaining the factitty status.
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NORTH AMMA - UNIT 1 5 3/4 8-1
f 3/4.8 ELECTRICAL POWER SYSTEMS BASES 3/4.8.1 and 3/4.8.2 A.C. and D.C. POWER SOURCES AND DISTRIBUTION The OPERABILITY of the A.C. and D.C. power sources and associated distribution systems during operation ensures that sufficient power will be av611able to supply the safety related equipment required for 1) the safe shutdown of the facility and 2) the mitigation and control of accident conditions within the facility. The minimum specified independent and redundant A.C. and D.C. power sources and distribution systems satisfy the requirements of General Design Criteria 17 of Appendix "A" to 10 CFR 50.
With a generator breaker installed on Unit I and normally open ties between buses 1H and IB and between buses 1.' and 2B, each 4 kv emergency bus will have two physically independent feeders from the offsite transmission network. The two offsite feeders to emergency bus 1H will be physically indepenaent from the two offsite feeders to emergency bus 1J. Each emergency-to-normal bus tie will have a normally open breaker at each bus.
The ACTION requirements specified for the levels of degradation of the power sources provided restriction upon continued facility operation commensurate with the level of degradation. The OPERABILITY of the power sources are consistent with the initial condition assumptions of the accident enalyses and are based upon maintaining at least one of each of the onsite
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A.C. and D.C. power sources and asso::iated distribution systems OPERABLE during accioent conditions coincident with an assumed loss of offsite power cnd single failure of the other onsite A.C. source.
l The OPERABILITY of the minimum specified A.C. and D.C. power sources and cssociated distribution systems during shutdown and refueling ensures that 1) the facility can be maintained in t5e shutdown or refueling condition for cxtended time periods and 2) sufficient instrumentation and control capability is available for monitoring and maintaining the facility status.
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NORTH ANNA - UNIT 1 B 3/4 8-1 l
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