ML20085K123
| ML20085K123 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/23/1991 |
| From: | Shelton D CENTERIOR ENERGY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR 1974, GL-91-06, GL-91-6, M81433, TAC-M81433, NUDOCS 9110300157 | |
| Download: ML20085K123 (6) | |
Text
...
W%
~
A CENTERIOR ENERGY Domsid C. Shelton 300 Mdson Avenue Vce P teient Nuclew Toledo, OH 436520)01 Deb Bette (419)249 2300 Docket Numbe 50-346 License Number NPF-3 Serial Number 1974 October 23. 1991 tinited States Nuclear Regulatory Commission Document Control Desk Vashington, DC 20555
Subject:
Response to Nuclear Regulatory Commission (NRC) Generic Letter 91-06, Resolution of Generic Issue A-30, " Adequacy of Safety-Related DC Pover Supplies", Pursuant to 10CFR50.54(f)
Gentlemen:
Nuclear Regulatory Commission (NRC) Generic Letter 91-06 (Toledo Edison letter Log Number 3460) dated April 29, 1991 advised licensees of the NRC staff positions resulting from the resolution of Generic Issue A-30, Adequacy of Safety-Related DC Pover Supplies, and requested that s
each licensee provide a written response to the questions in.
Accordingly, attached is Toledo Edison's response for the
~
Davis-Besse Nuclear Power Station (DBNPS) to Enclosure 1 of Generic Letter 91-06.
Should you have any questions concerning this matter, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing at (419) 249-2366.
Very trul,y yours, Q fj f
</N % x3 MHL/dlm attachments cci A. B. Davis, Regional Administrator, NRC Region III J. B. Hopkins, NRC/NPR DB-1 Senior Project Manager V. Levis NRC Region III, DB-1 Senlot Resident Inspector Utility Radiological Safety Board 9110200157 911023 e
,, P O R ADOCK 050003A6 P
PDR A
.-g
{
't Opeeng Componies
{
C*eiondiiecmc liiun nchng i
n Imaco f a son
Docket Number 50-346 License Number NPT-3 Serial Number 1974 Page 1 RESPONSE TO GENERIC LETTER 91-06 FOR DAVIS-BESSE NUCLEAR POWER STATION UNIT NUMilER 1 This letter is submitted pursuant to 10CFRSO.54(1).
Enclosed is Toledo Edison's response (letter Serial Number 1974) to Generic Letter 91-06, Resolution of Generic Issue A-30, " Adequacy of Safety-Related DC Power Supplies."
/
- f,
" \\ __ ~~')
By:
i s
D. C. 5I2 ton, Vice Pr esident - Nuclear Sworn and subscribed before me this 23rd day of October.
ALW-Notary Pub c, State of 0hio EVELYNL DRESS RNeueUC STATEOFCHO
%WEWesJuly41S t
i l
._.___e____.__
Docket Number 50-346 License Nember NPF-3 Serial Nuober 1974 Page 1 TOLEDO EDISud RESPONSE TO GENERIC LETTER 91-06 The NRC requested the following information in Generic Letter 91 06.
The station DC power system equipment consists of two 250/125 VDC motnr control centers (DC HCC 1 and DC HCC 2), f our bat teries (111, IP, 2N, and 2P),'six battery chargets (DBCIN, DBCIP, DBrlPN, DBC2N, DBC2P, and DDC2PN), four essential distribution panels, four 480VAC/125VDC rectifiers, and four nonessential-distribution panels. The system is arranged to form two completely independent load groups.
Section 8.3.2 of the Davis-Besse Nuclear Power Station (DBNPS) Updated Safety Analysis Report (USAR) provides a more detailed description of the DC power system..
i Toledo Edison's responses are underlined.
1.-
Unit:
Davia-Besse Nuclear Power Station Unit 1 0
2.
a.
The number of independent redundant divisions of class 1E or safety-related de power for this plant is two (2).
(Include any sepatate Class lE or safety-related de, such j
as any de dedicated to the diesel generators.)
b.
The number of functional safety-re)ated divisions of de power necessary to attain safe shutdovn for this unit is one (1).
3.
Does the control room at this unit have the folioving separate, independently annunciated alarms and indications for each division of de pover?
a.
Alarms 1.
Battery disconnect or citcuit breaker open?
to --at j
i Davis-Besse there are no annunciated alarms for the station battery disconnects.
However, the battery j
disconnects are verified closed at least once ger shif t and documented in Equipment Operator log sheets.
TIIe'~~
log sheets are procedurally controlled.
2.
Battery charger disconnect or circuit breaker open (both input ac and output'.de)?
Yes - (input ac circult breaker) For division 1._if a.
a liattery charger input breaker is openedIthe "DC
~
iftiS 1 TRBL" control room annuncl~ator vfil alarm
- once the charger input voltage drops to less than or equal to 432 VAC.
The same annunciator vill eventually alarm once voltage on the DC bus drops below 127.1 VDC (asj he battery discharges h Division 2 is similar, except the annunciator i
vindov-reads "DC BUS 2 TRBL."
There are no alarms driven directly by the mechanical position of the l
EGEker.
- e ee, w
w,get A-
-r-v A-ew
=-
vwr-w--
w e
gee
--r-wp-4 pe w + i w m-m syw- :ws see-o
-w g,w g. w w - g w
.? ww>w pi w
..n.-+,yvw.me3.e-
+g$w?,+----tr,yeeg=1q y P y y -ew-w ev R 4-'v%*y
%e.uw.
.g=y
Docket Number 5D-346 License Number NPP-3 Setini Number 1974 Page 2 b.
Yes - (out & de disconnect) For division Inif a bat tely cliat;ger output disconnect is opened, the "DC BUS 1 TRtlL" control roem annunciator vill IMo~v~lFl[.T VDC (as the hiiter)idaim once voltage on tIIe DC eventtiaiI
~
discharges),
iiivision 2 is simlTat, except thiannunciat5t UliiIlov reads "DC BUS Y 'l AllL."
These are no alatms ilt ivFiillTi'ec'ilv_ by the mecTinnical position or'Tlie~
disconnect.
Note 11 cithet the input ac circuit breaker et the output"dc disconnect is openiL ~ihe "br FANEl VUI~ finn EUI annunciator Vill even_tually alatm once voltage on The DC distribiillon panel drops to l'iss than oc ejliiiT Is 116 VDC. (as th bat t cry 'dischangisPITils annuncGtor is common to both dT a lens.
3.
DC system ground? No - There is no annuticiatot, howevet j each_ DC sys t em (ifvTs i on Ls a~ sepa ra t e and Milidiident comnter_ point alarm vTilgvill _ indica t e a g.: ound.
4.
DC bus-undervoltage? Yes - An undervoltage condition on the division 1 bus (DC MCC I) vill tesult in tTie W c D
DllS T TRDli" cont r ol roorr.nnunciator aGaming 5~lmilailv,anundervoltageconditiononthedfvision2
_ hus,,jQiINCli 7[lifl1 l t esult ~ f tiltlie WFlib5~DkBL" conttol room annunciatot alarming.
The alarm stitpoint~
~
3_s._,12 7~l VDC.
S.
DC bus ovetvoltage? Yes - An ovntvoltage condition on the division 1 bus (DFFETj~sfTT tesuliTri ihe aDC liUS i TRht" conttol room annunc GIIsr alarm gin.
hiiiIIUIh an ovet voltage conIITtliin on the division 2 bun (fiC MCC 2) vilT esult in tIieDC llVS 2 TRDL" control toom antienclatot alarming.
1he alarm satpoint TiTD.9 VDC.
6.
Dattery chatget Iallure? Yes As decerlbed aLove,_in the event of a division' I charger fat 1uro (undervoltage condTtionfu tfie "DC lius 1 That," cont rol room annunc i a t o r IITTi~a'l a t ni.~~5I'mTl a rly, in the event of a divisioii 2 chargir7~faTlui3 the "bC BUsl Tnota control
~
iooma'nnunilatorvlI1]Tarm.
~
7.
Battery discharge? No - There h no annunciator, however, each hat terfTiss a separa'te and independent computerpyntalarmWilchvillindicatewhenthe liiItiiifTs dTscharging at 'a rate of 25 amperes or mor e.
Docket Number 50-346-1.icense Humhet NPF-3 Serial Number 1974 i
Page 3 b.
Indications 1.
Battely float charge current? No - A charge / discharge cuttent meter is ptovided in the conttol room 2 however, the meter span l0 to 800 ampetes) is too latge to distinguish the float current ( tzpically I ampet e).
2.
Battery circuit output current? Yes - The control toem has a charge / discharge currtnt meter vith a span of 0
}
to 800 amperes.
3.
Battery discharge? Yes - The control room has a charge / discharge current meter with a span of O jo 800 amperes.
4.
Bus voltage? Yes - For the division 1 bus (DC MCC 1),
the control board has a meter (0 to 150 VDC) for Ti2TYDT I)ur IP, a meter (0 to_tSO VDC) for -125 VDC bus TN, and a meter (0 to 100 VDC) for 250 VDC btis 1.
There are similar meters for the division 2 bus (DC HCC 2).
c.
Does the' unit have vritten procedures far response to the above alarrrs and indications? Yes - procedures are in 1
place for responding to annunciator alarms.
The computer point alaims-anTiic system division indications are monitored during each shift. Any abnormalities are logg$e.d and 4eported to station lilectricaf~ Maintenance.
4.
Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect _the battery changer from its de bus and the battery
-charger irom its ac power source _during_ maintenance and testing? No - Davis-Besse does not have control-rooia indication of_ bypassed or inoperable circuit breakers or disconnects for the station batteries and normal chargers from-the DC buses. There is M an no indIEation that the normal bat tery chargers Od ysconnected f rom the: AC power source.
There are TiidicMion lights and computer points available to indicate if a sving charger is supplying a DC bus.
If a sving chatger is supplying a bus, this implTes that-the normal-c}Ia rget is-secure firom the bus as per station procedures.
5.
11 the answer to any part of question 3 or 4 is no, then provide information justifying the existing design features of the facility's safety-related de systems.
The existing-desigrj features as described in the responses to questions three and four are part of the Davis-Besse Ficensing basis. The compensaToryactionsforfailures,-bypassing-anffiio3tability are (Tescrlhed-in the responses to _ questions three and four.
l l:
i
(;
I l
l-L
. m..
m -,,
__..;___.u__..
.2.
Docket Number $0-346 License Numbet NPF-3 i
Serial Number 1974
+
Page 4 6.-
(1) llave you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one de division to be unavailable? _No - An explicit review of maintenance and testing ~ activities which specifically a3 resses this issue has not 6 Tin done, however, precautions-~
andJ terequisTies on preventing concutrent maintenance and 17 sting on two DC Ji_ visions are ideritTffida in-the iT57/NvDC switching procedure and the DC system maintenance Lrocedures.
i:ach DC division Tevice has a unigue numerle label _ which zrevent mistakes in_ manipulating,,a wrong device on the same aus and (2) do plant procedures prohlblt maintenance or testing on redundant de division at the une time? Yes -
Station battery and charger surveillance and test ptocedures
-iiave administ ra t ive _ pret equisites and pt ecaut ions which pt event ETritiTinneous maintenance or testing on redundant DC divTsions.
- 7. -11_ the _ f acility Technical Specifications have provisions equivalent to-those found in :he Vestinghouse and Combustion Engineering Standard Technical Specifications for maintenance and surveillance, then question 7 may be skipped and a statement to that effect may be inserted here.
Amendment 100 to the_ Davis-Besse Operating License (NRC letter 3ated 3/12/87)
~
re'W sed the surveillance requirement foi the D.C. distribution system, includliig~~tfiE batteries and battery efiargers for both op'et aling and shutdown modes. This amendment was concistent Uith the NRC guidance provided liy model TSs for statlijn bat tet fes (NRC let ter Jiily 16, 1986).
l 0.
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? Yu i
b.
Reactor coolant system integrity and isolation capability are maintained? Yes Operating procedures, instrumentation (including indicators c.
and annunciators), and control functions are adequate to initiate systems as required to maintain adequate core cooling? Yes 9.
If the answer to any part of question 6, 7, or 8 is no, then 4
provide your-basis for not performing the maintenance, surveillance and test procedures.descrlhed and/or the bases for.
not including the operational features cited.
N/A j
b l
i I
l:
YL -. e
,_7_..-
.- - _., _....., _,.... - _. _ _. _... _ _ _... _.~.. _. _.- _ _.- _ _ - -
-