ML20079L385
| ML20079L385 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/29/1991 |
| From: | Sieber J DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR GL-91-06, GL-91-6, TAC-M81410, TAC-M81411, NUDOCS 9111060248 | |
| Download: ML20079L385 (14) | |
Text
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De ver Va ley Power Slabo" Sh%nngport, PA 16017 0004 (4th 393 5255 v$'.*nS.I[n7sucw o,oup october 29, 1991 U.
S.
Nuclear Regulatory Commission Attn:
Docu.nent Control Desk Washington, DC 20555
Subject:
Boavor Valley Power Station, Unit No. 1 and No. 2 BV-1 Docket No. 50-334, License No. DPR-65 BV-2 Docket No. 50-412, License No, NPF-73 Response to Gencric Letter 91-06, Resolution of Generic Issue A-30 " Adequacy of Safety-Rolated DC Power Supplies" (Tact,81410 andr81411)
Attached is our respcnse to the recommendations as requested by Generic Letter 91-06, Resolution of Generic Issue A-30 " Adequacy of Safety-Related DC Power Supplies," pursuant to 10 CFR 50.54(f).
Please note that this submittal provides information addressing both Beaver Valley Unit 1 and Unit 2.
If you have any questions regarding this response, please contact Andrew G. Johnson at (412) 393-5295.
Sincerely, 2r D.
Sieber cc:
Mr. J.
Beall, Sr. Resident Inspector Mr. T. T. Martin, NRC Region I Administrator Mr. A.
W. DeAgazio, Project Manager Mr. M.
L. Bowling (VEPCO)
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COi4MONWEALTH OF PENNSYLVANI A)
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Commonwealth and. County, personally appeared J.
D. Sieber, who being.
duly sworn, deposed, and said that (1) he is Vice Pret.ident - Nuclear of-Duquesne Light, (2) he is duly authorized to execute and. file the foregoing _ Submittal on behalf of said company, and (3) the statements
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set _ forth in the Submittal are true and correct to the best of his knowledge,-information and belief.
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ATTACHMENT 1 DY11_Reapsnns_tsLGenetic._ Letter 91-OLQRCD.t19D.S QR011tipJ1_1 The following information is to be provided for each unit at each site.
EC2DQDjiL_1 The following responses cover botl. Unit 1 and Unit i at Deaver valley Power Station (BVPS).
QMrstion 2.a The number of independent redundant divisions of Class 1E or safety-related de power for this plant is (Include any separate Class 1E or Safety-relate 1 dc, such as any de dedicated to the diesel generators.)
Responso 2.a BVFS Units 1 and 2 cach have two jndependent redundant tra.nn of Class 1E 125 VDC pownr.
Each train of class 3E DC power consists of two independent Class 1E 125 VDC buses.
Quqttinn 2.b The number of functional safety-related divisions of de power necessary to attain safe shutdown for this unit is 89BD9RG9_.2a.h BVPS Unit 1 and Unit 2 cach require only one train of Clas-IE de power to attain safe chutdown.
QRtEtlilD 1 Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of de power?
a.
Alarma 1.
/. 'tery disconnect or circuit breaker opa;G 2.
Battery charger disconnect or circuit breaker open (both input ac and output de)?
3.
dc system ground?
4.
dc bus undervoltage?
5.
de bus overvoltage?
6.
Battery charger failure?
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a
.Attachmont 4,
continued Page ?
7.
Battery discharge? __
b.
Indications 1.
Battery float chargo curront?
2.
Battery circuit output current?
3.
Battery dischargo?
4.
Bus voltage?
c.
Does the unit have written proceduros for resoonse to the above alarms and indications?
Rosoonso 3.a (Alarnal - For further details,-sco Attachment 2.
3.a.1 Battery Disconnect or Circuit Breaker Open.
BV - - No DV - - No 3.a.2 Battery Charger Disconnect or Circuit Breaker open.
BV - No BV - - No 3.a.3 DC System Ground BV - - No BV - - Yes 3.a.4 DC Bus Undervoltage BV - Yes BV - - Yes 3.a.5 DC Bus Overvoltage BV - - No DV - - No 3.a.6
. Battery Charger Fa31uro BV - - Yes
-BV - - No
=3.a.7 Battery Discharge BV - - No BV - - No EcEnonan 3.b (Indictional - For furthur details, soo Attachment.2.
3.b.1 Battery Float Chargo Curront BV - - No-BV - - No k
Attachmont 1, continued Pago 3 3.b.2 Battery Circuit output Current BV - - No DV - - No 3.b.3 Battery Discharge BV - - No BV - - No 3.b.4 Bus Voltago BV - - Yes BV - - Yes Enanonse 3 9 BV-1 and BV-2 have procedures to respond to all subject a? arms / annunciators that are roccived in the control room.
They includot DV-1 Battery Breaker Overcurront Trip Low Bus Voltago Battery Charger Failure DV-2 Battery Breaker Overcurrent Trip Low Bus Voltago Battery Charger Troublo Bus Grounds Safety System Train Inoperable Bus voltage and bus ground motors in the control room are monitored and recorded, por equipment operating logs, each shift.
L Qupstion 4 Does this unit have indication of bypassed and inopc.able status of circuit breakers or other devices that can be used to disconnect.the battery and battery charger from its de bus and the battery charger from its ac power source during maintenance i
or testing?
Responso 4 - For further details, soo i.ttachment 2.
DV - - No BV - - Yes **
l Bypassed and inoperable status indication (BISI) is provided for the connected / disconnected status of two of the 4 BV-2 battery breakers.
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Atta'chment 1, continued i
Page 4-Quqation-5 If the answer to any part of Question 3 or 4 is no, then provido i
Information justifying the existing,Soo noto below.
design features of tho l
facility's safety-related de systems.
- Note For questions involving supporting typo information (Questions numbers 5
and 9) instond of developing and supplying the information in responso to this letter, you may commit to further uvaluate the nood for such provisions during the performanco of your individual plant oxamination for severc accident vulnerabilities (IPE).
If you select this option. you are required tot 1
(1) So stato in response to those questions, and (2) Commit to a<plicitly address Questions 5 and 9 in your IPE submittal p.t the guidelinos outlinod in NUREG-1335 (Soction 2.1.6, Subitom 7), " Individual Plant Examination:
Submittal Guidance."
Resoonse 5 i
Soo Attachment 2
for support information for respor.aos to Questions 3 and 4 justifying oxisting design featuros.
Quantinn_1 4
(1) Have you conducted a
review of maintenance and testing activities to minimizo the potential for human error causing more than one de division to be unavailablo?
and (2) do plant proceduros prohibit maintenance or testing i
on rodundant de divisions at the samo time?
Eggponso 6.1 (Roview of Maintenanco and Tgsting Activition)
BV - - No BV - - No For further details, 000 Attachmont 2.
Ennponso 6.2 (Plant Proceduro Rostrictions)
BV - - Yes BV - - Yes Maintenance procedures that rondor one safety-related redundarit de component unavailable but not on clearance contains a
precaution or initial condition to verify the redundant component is in service prior to start of work.
In casos where the equipment to be taken out of servico is placed on clearanco, the clearance proceduro requires the NSS to complete an Emnrgency Safeguards Equipment Clearance Checklist.
The checklint verifies the standby equipment is operable.
Technical Services Department testing proceduros are developed to assure that the other redundant de division is available prior to beginning testing.
__, -. _ ~,, _.. -
- Attachront 1, continued Page 5 Question 2 If the facility Technical Specifications have provisions equivalent to those found in the Westinghouso and Combustion Engincoring Standard Technical Specifications for maintenanco and survoillanco, then Question 7 may be skipped and a statomont to that offect may bo incerted here.
Are maintenance, surveillance and test procedur9s regarding station batteries conducted routinely at this plant?
Specifically:
a.
At least once por 7 days are the following verified to be within acceptable limits:
1.
Pilot cell electrolyto levol?
2.
Specific gravity or charging current?
3.
Float voltago?
4.
Total bus voltage on float charge?
5.
Physical condition of all cells?
b.
At least onco per 92 days, or within 7 days after a battery dischargo, overchargo, or if the pilot call readings are outsido the 7-day surveillanco requirements are the following verified to be within acceptablo limits:
1.
Electrolyte level of each coll?
2.
The average specific gravity of all cells?
3.
the specific gravity of each coll?
4.
L.e average electrolyte temperature of a representativo number of cells?
5.
The float voltage of each coll?
=_
6.
Vicually inspect or measuro resistance of terminals and connectors-(including the connectors at the dc bus)?
c.
At least every 18 months are the following verified:
1.
Low resistance of each connection (by test)?
2.
Physical condition of the battery?
E!?dFJWN5JWJWe At uh:ent 1, continued v.gr 3.
Battery charger capability to deliver rated ampero output to the de bun?
4.
The capability of the battery to deliver its design duty cycle to the dc bus?
5.
Each individual ecl1 voltage is within acceptable limits during the servico tent?
d.
At least ovary 60
- months, in capacitv of each battery verified by performance of a discharge tev o.
At least
- annually, in the battery capacity verified by performance dischargo
- tent, if the battery shows signa of degradation or has reached 85% of the expected service life?
RetipJ2nce.1 The BV-1 and BV-2 Technical Specifications are in most cases identical to those of the Westinghouse Standard Technical Specifications.
With the exception of several plant specific
- values, the only differences between the Technical Specifications are as follows:
The time period for testing battery chargers at rated capacity 10 (8) hours in the Westinghouse Standard Technical Specifications vs (4) houro at BVPS.
The Westinghouse Standard Technical Specificationn require annual battery testing-for batteries showing signs of degradation, or naving reached 85% of its service life vs.
18 months at DVPS.
QREP3i_91LB Does this plant have operational features such that following loss of one safety-related de power supply or bus:
a.
Capability is maintained for ensuring continued and adequate reactor cooling?
b, Reactor coolant system integrity and isolation capability are maintained?
c.
Operating procedures, instrumentation (including indicators an annunciators).
and control functions are adequate to initiate systek; as required to maintain adequate core cooling?
a Attdchment 1, continued Pago 7 Resnonse 8.a & 8.b BV-1 and DV - - Yes The BV-1 and BV-2 Class 1E DC power systems are designed with sufficient independenco and rodundancy to perform their safety function assuming a
single failure.
DV-1 and DV-2 both satisfy the requirements of GDC 17
" Electric Power Systems."
GDC 17, which requires that an electric power system be provided which has sufficient capacity and capability to assure the core is cooled and containment integrity and other vital functions are maintained, also requires that onsite olactric power systems, including batteries and onsito electrical distribution systems, perform their safety function assuming a single failure.
Resconse 8.c BV-1 and BV - - You BVPS Units 1 and 2 are both provided with two redundant trains of Class 1E de power (orange and purple).
Each train is comprised of two Class 1E 125 VDC buses.
Each train has the capability of performing its required safety function regardless of the state of operability or failuro of the other.
operating procedurer are available at each unit for startup, shutdown or continued operation of the de power systems.
Procedures are also available for correcting safety related alarms and clearing grounds on the Class 1E 125 VDC buses.
Sufficient controls alarms and indications are provided to allow for safe rollable operation and to alert operations personnel of abnormal conditions when they occur.
Adequate instrumentation is available for identifying specific component failuros.
Soo response to Question 3 in Attachment 2 for additional details.
Question 9 If the answer to any part of Question 6, 7 or 8 is no, then provide your basis for not performing the maintenance surveillanco and test procedures described an/or the bases for not including the operationr.1 features cited.
- See note below.
N
- Not'et F$1-qt,1estions involving supporting type information (Question number 5
and 9) instead of developing and supplying the information in response to this letter, you may commit to further evaluate the need for such provisions during the performance of your individual plant examination for severe accident vulnerabilities (IPE).
If you select this option, you are required to:
(1)
So stato in response to these questions, and
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9 Atta'chment 1, continued Page 8 (2)
Commit to explicitly address Questions 5 and 9 in your IPE s.bmittal por the guidelines outlined in NUREG-1335 (Soction 2.1.6, Subitom 7),
" Individual Plant Examination:
Submittal Guidance."
Rosnonse 9 Soo Attachment 2
for support information for responses to Questions 6, 7,
a 'id 8.
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9 ATTACllMI:NT 2 Support Inf ormation Justifying 1:xinting Design l'entures for Quentionn $ and 9 (3.a.1)
No BV-1 DV-2 Ilattery Disconnect or Circuit Ilreaker Open Alarms in Control Room.
DV-1 and
!!V-2 both receive alarma in the control room for each battery breaker that openn an a result of overcurrent.
Indicating lightn are provided in the control room for each clans 11: 125 VDC battery breaker.
A red light in illuminated only when its roupective battery breaker is i
in the connected (operating) ponition with its main contactn closed.
BV-2 battery breakers
- 2-1 and *2-2 llluminate a 11181 window when not in the connected /opelato position.
The change of status of all claun IE 12b VDC battery i
breakers (open/close) la printed on the computer.
(3.a.2)
No BV-1 & BV-2 Battery Charger Dinconnect or Circuit Breaker Open Alarms in Control Hoom.
All of the Class IE 12b VDC Busca at BVPS hrsve instrumentation to annunciate on low 125 VDC bun voltage.
The opening of a
battery charger circuit breaker or disconnect switch will immediately renult in the 125 VDC Dun Voltage dropping below the under voltage setpoint causing a low 125 VDC buo annunciator to be received in the control room.
The ac-In and de-out battery charger circuit breakura of all DV-1 Class 1E 12S VDC busca and BV-2 Clano 10 125 VDC busca
- 2-1 and
- 2-2 are instrumented with indicating lights which provide open/cloue statun in the control room.
A red light will be illuminated only when both the ac-In and de-out circuit breakers are l
closed.
Additionally, at DV-1 the red light will be I
extinguished if the AC aupply voltage to the chargera dropa below 400 VAC.
(3.a.3)
No DV-1 System Ground Alarm in Control Room.
The BV-1 Claan IE 125 VDC busca are instrumented with l
ground volt meters capable of detecting high reciatance ground on their associated bus.
These volt motors are monitored each shift to be within specified limitu.
Monitoring each shift in considered adequate to protect against bus ground problems which muut occur on both the positive and negative bus leada simultaneously to affect the operation of a 125 VDC bus.
Additionally, the importance of removing grounds immediately upon detection is stressed at BVPS.
. _ ~
Atto'chment 2 (continued)
Pago 2 j
(3.a.4)
NA, do Bus Undervoltage Alarms are provided For BV-1 and BV-2 in Control Room.
(3.a.5)
No BV-1 & BV-2 Overvoltago Alarm Provided in Control Room.
125 VDC Bus overvoltago is considered to be a highly un:
oly condition to occur.
Virtually all postulated con snont/ equipment failures would result in a low bus Voltano condition which is annunciated in the control room.
Should a
sustained high bus voltago condition
- occur, it would be detected through normal monitoring of 125 VDC bus voltages which is dono cach shift to ensure the bus voltages are within obtablished limits 145)
VDC.
liigh voltage transients on the of (125 battery charger power supplies would be filtered by the stopdown transformers at the input to the charging Components.
(3.a.6)
No BV-2 Battery Charger failuro Alarm in Control Room.
BV-2 has 4 Class IE 125 VDC busos.
Busos *2-1 and *2-2 have dedicated chargers.
Buson
- 2-3 and *2-4 havo rectiflor/ chargers.
Those rectiflor/ chargers, in addition to providing the charging function for 125 VDC busos
- 2-3 and
- 2-4, also nupply de poWor to the Uninterruptibio Power. Supply (UPU) vital bus inverters
- 2-3 and
- 2-4.
The loss or failure cf a BV-2 battery charging component would rouult in a 125 VDC bus under voltage condition which would bo immediately annunciated in the control room.
The BV* 2 class 1E 125 VDC battery chargers *2-1 and
- 2-2 have power monitora which provide for annunciation in the control room on low AC supply voltage to their associated charger.
The BV-2 chargers *2-1 and *2-2 havo indicating lights which provido opon/closo status of the charger ac-In and de-out circuit breakers in the control room.
Soo response to 3.a.2 above for battery charger indicating Jight logic..
An annunciator is roccived any time a BV-2 battery is supplying its associated UPS vital bus inverter.
A failure of the chargers (rectiflor/ chargers for 125 VDC besos
- 2-3 and *2-4) would initiato this annunciator-in the control room.
Bus voltage for each BVPS Class 1E 125 VDC bus is monitored each shift to ensure that the bus voltages are within established limits.
i
., continued f
- Pago 3 t
(3.a.7)
No BV-1 & BV-2 Battery Dischargo Alarm in Control Room.
Each BV-1 and DV-2 Class 1E 125 VDC bus in monitored each shift in the control room and each day at tho nwitchgoar for voltage 2 125 VDC.
4 Each BV-1 and BV-2 class 1E 125 VDC bun han i
annunciation in the control room for low voltago (125 VDC at BV-1 and 129.4 VDC at BV-2).
Assuming a battery with no more than 60 cells in sorica, any undervoltago not point 2
124.2 VDC (2.07 VPC, which la tho open circuit potential of the lead calcium colla installed at DVpS) annures that the bus potential in high enough to provent the battery from discharging.
Thun, the discharging' of any' Class 1E battery could not go undotected.
Ammotors for each BV-1 and BV-2 Class 1E 125 VDC bus battery
-are provided at the battory breaker switchgoar.
Those ammotorn are monitored daily to onsure battery currento are within established limito.
- (3.b.)
No BV-1 & BV-2 Indications in Control Room Fort 1.
Battery Float Chargo Current 2.
Battery Circuit Output Current
-3.
Battery Dischargo r
Each BV-1 and BV-2 Clano 1E 125 VDC bun han annunciation for undervoltago.
This undervoltago not i
point assurco that each clano IE 125 VDC bun potential is high enough to be supplying its roupoetive battery and that the battery is not discharging.
Son response to 3.a.7 above for setpoints.
Dattery curront ammotors are provided locally for each
[
Class 1E 125 VDC bus.
Battery currents are monitored daily to be within limita.
(3.b.4)
NA, bus -voltago. indication'io provided in the control room for each DV-1 and BV-2 claan IE 125 VDC bus.
(3.c)
NA, BV-1 and BV-2-have proceduros for all availablo control-i roor-alarms.
(4.);
No bypanned and inoperable status of components unod to disconnect the battery and battery charger,
Attachm:nt 2, continued page 4 Each BV-1 and BV-2 Class 1E 125 VDC battery charger /rectiflor-charger has an ac-In circuit breaker, a
de-out circuit
- breaker, and a
dc-out disconnect switch.
The opening of any of thoso devices would immediately result in a
125 VDC bus under voltago condition which is annunciated in the control room.
- Thus, the disconnection of a battery charger /roctiflor charger could not go undetected.
The BV-1 Class 1E 125 VDC systems do not have a disconnect switch betwoon the battorios and the busos.
The BV-1 and BV-2 battery breakors are instrumented with indicating lights which provido operational status of the battery breakers in the control room - the red indicating light is only illuminated when the battery l
breaker is in the connected (operating) position with its main contacts closed.
At BV-1, the green light is extinguished for this samo condition.
)
(6.1)
Review of BV-1 & BV-2 Maintenance and Testing Activities not i
conducted.
Maintonence has not performed any formal review of maintenance activitics for human orror causing more than one safety-related redundant de component to be unavailable.
- However, periodic reviews are routinely performed to identify potential problem areas.
Those reviews are based on foodback from previous completed maintenanco activities (i.e.,
Proventive Maintenance and Maintenance Work Roquest
- reviews, Maintenance History
- reviews, LER's, etc.)
and industry noticos (i.e.,
- NRC, INPO, Tech Bulletins, etc.).
Changes to plant procedures and/or training programs are based on this foodback.
In
- addition, all Maintenance procedures receive a
human factors review as part of the Procedure Upgrado program.
Ah,though formal review of Technical Services Department (TSD) testing activities has not boon performed TSD testing procedures are developed and reviewed to minimizo the possibility of human error by requiring that the other rodundant de division is available prior to the start of testing.
(6.2)
NA, plant procedures prohibit maintenance or testing on redundant de trains / component at the same time.
i (7.)
NA, BVpS Technical Specifications are equivalent to Westinghouse Standard Technical Specifications.
(8.)
NA, BV-1 BV-2 have adequate operational feature to compensato for loss of one safety-related de power supply or bus.
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