ML20080M748
| ML20080M748 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/08/1983 |
| From: | Morley G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Gears G NRC |
| References | |
| GL-81-12, NUDOCS 8402210279 | |
| Download: ML20080M748 (13) | |
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y PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET s
x P.O. BOX 8699 PHILADELPHI A. PA.19101 (2151841-4000 eAugust 87 l983
Docket Nos.50-277 50-278 4.
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N Mr. Gerry Gears N
V Mail Stop 416 Phillips Building U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, MD 20014
Subject:
Peach Bottom Atomic' Power Station Alternative Shutdowd Systea'and Comparison to Generic Letter 81-12
Reference:
Generic Letter 81-12 and Clarification Letter t
Dear Mr. Gears:
Generic Letter 81-12 and the clarification letter to Generic Letter 81-12 require that substantial amounts of information be provided for those areas of the plant for which an
-alternative shutdown approach.ics used to achieve safe shutdown.
A During the meeting between Philadelphia Ele _ctric Company and the NRC on June 1, 1983, we proposed providing'some of this information in a drawing format as opposed to the tabular form suggested in the two letters.
The NRC indicated that they would i
entertain this alternative approach if they founds it workable.
s.
d To make this determination, PECo suggested that a sample of the drawing format be forwarded to the NRC along with a description of which paragraphs of the letters were to be addressed by the drawing format.
Attached is a drawing that shows the cab 1'esUforithG HPCI" (system",Tthe ;pr im ary s ys tem " to be us ed ' f or # al te rn a ti ve ; shut down. n c
r 8402210279 830808 3
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9' M'r. Gerry Gears.
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.The' applicable paragraphs of the referenced letters are addressed t'
in the attached document.
We are prepared to discuss any questions you may have on this subject.
Very truly yours,
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- w G. M. Morley Branch Head i -.' -.
Mechanical Engineering Division
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Attachment s,
cc W. J. Mindick W. M. Alden/MBR
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'o PRELIMINARY HPCI ALTERNATIVE SHUTDOWN DEFINITION FOR PEACH BOTTOM APS 1.0 Appendix R Section III. G. Evaluation Diagrams fi-The purpose of these diagrams is to
- present, on a
safe shutdown system basis, all the pertinent information necessary to conduct a safe shutdown equipment separation analysis in accord-ance to the regulatory requirements.
For PBAPS, these diagrams have been prepared for the followingGsafershutdownraystems:
High Pressure Coolant Injection (HPCI)"
Reactor Core Isolation Cooling (RCIC)
Automatic Depressurization ( ADS)' and non-ADS Safety-Reliel Valves.
Core Spray (CS)s High Pressure Service Water (HPSW)
Emergency Service Water (ESW)
Onsite AC Power Generation and Distribution (AC)
Onsite DC Power Generation and Distribution (DC) 5 These Evaluation Diagrams provide the following PBAPS in-formation for both Unitv4 x
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Major plant fire areas contained within rated fire
- barriers, by plant elevation (exceptions are the Reac-tor Building areas which contain equipment hatches).
These areas are not represented to scale nor do they necessarily correspond to contiguous rooms.
o Equipment location and identification (including in-strument racks and electrical distribution and control panels).
o Essential power and control cables interconnecting various system components and their location within fire areas.
The information contained in these Evaluation Diagrams fa-cilitates the followings o
An area by area (fire area approach) evaluation of postulated fire effects on safe shutdown systems and a
determination of areas for which redundant safe shut-down methods are separated by rated fire barriers; o
A" determination = of twhichsredundarit" system (or trains within.a particular system) is more appropriate for modifications to achieve III.G.2 compliance; o
Selection of adequately separated new cable routes or determination of areas where raceway fire protection is to be_used; o
A determination of which area (s) and system (s) are indicated for an alternacive shutdown
- approach, the required modifications, and the location for alternate control station (s).
o A
graphic demonstration of whi.ch essential cables for alternative shutdown are to be isolated from the fire area (s) of concern.
o A
graphic representation of the independence of the selected equipment and cables (of the alternative shut-down method (s)) from the fire area (s) of concern.
o A
determination by fire area of potential ascociated circuits and the resolution selected.
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2.0 HPCI Alternative Shutdown Control When the Evaluation Diagram for HPCI (refer to drawing #
E-101) is compared to the same diagrams for the remaining safe shutdown systems it becomes apparent that an alternative-shutdown metho,d,is requir_edufor the. Cable.SpreadingsRoom.
This fire area' a
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- is*especially,sensitivembocauseccontrol circuit. cables-for allsof.
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4the';HPCI" safe' shutdown components"a're' routed"in ; this c zone. -Since.
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a similar# sit'ua' tion
- exits"for-the4ControlcRoom, a modification of s
the HPCI system is proposed to provide an independent (and alter-native) control station that will satisfy the inventory control function for a postulated fire in these two areas.
TheJproposed,
t alternativeaHPCI: control; station:..is to be located in the vicinity of the :HPCI main *DC' motor" control' center'(20D11 and 30D11 for#
": Units *2*and"3Fiespect'iveM).
The alternative shutdown method to be provided for the HPCI f
system to comply with the provisions of Appendix R involves:
(1)
Electrical isolation, via the use of'tfansferiswfsoh58,*
of those electrical circuit cables which can be im-pacted by a postulated fire in the areas of concern; and (2)
Re-establishment of those electrical circuit functions and equipment operation Lf trarisfer of circuit control and power to the alternative local control station.
,0nc_e ityhas<beenxdetermined that control =of
- the' HPCI systeac%m.,
y isy;no, longer poss.ible from the M.ain Contro1 Room, man, operator..,
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e=Will b.e dispatchedatorthe1HPCIe AlternativerControlv: Station.
This r
a station will allow operation of all HPCI components necessary for long term system operation (a list of the vital HPCI components Page 3
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,g is? attached).
Thisepanelawill.salso display thgnecessary, planty 3,n x
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dinetfumefitatthit*feF# safe shutdownc "
v m t,.u_he,Hy I syge g the operator will
-Before igitiation o
t operate. the *tPsfisfiF*sifif6his and will take local control to ensure proper valve alignment.
Once valve alignment is finished the gland seal vacuum-pump will be started along with the auxil-Jiary oil pump.
The auxiliary oil pump will develop sufficient oil pressure to open the turbine stop and control valves.
The turbine will then be started by opening the steam inlet valve
'(MO-14 ). -
System flow will be controlled by manually adjusting the-setpoint of the new local flow controller, with the actual
.HPCI flow signal received from the existing flow transmitter located at the,HPCI instrument rack.
Reactor vessel inventory will be increased until vessel
. level matches.the high level point.
At this point the HPCI tur-b'ine could be shut off by closing the steam inlet valve.
The foperator.'could then continue to monitor Reactor Vessel water l
level and repeat this procedure as required to maintain the core
. covered.
iThe HPCI -alternative control station also contains suffi-
.cient controls to allo'w the operator to use the full flow test return 'line to the condensate-storage tank for fine control of reactor-pressure.-
This is accomplished by taking suction from h
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the condensate storage tank and, opening the full flow test return line.
'The turbine is then brought up to sufficient flow to draw Page 4 a u sei n i il
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steam from the Reactor vessel at a rate equal to or greater than that' generated by dec"ay. heat.
HPCI is capable of removing energy
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at a
rate in excess of that produced by decay heat within two hours after shutdown.
automaticj For the alternative shutdown control method, no Transferf f
HPCI initiation or shutdown signals will be used.
a switches. will provide' isolation of all control wiring from thed M
HPCI motor control center to.the Cable 3preading and Control'!
3 Rooms for motor-operated valves, auxiliary oil pump, vacuum andj solenoid.4'g gland seal condenser pumps and turbine auxiliary trip 6
. Furthermore, sinos modifications to existing instrumentation; Q
- wiringwillisolatetheturbinespeedcontrolcircuitrytransfer-g i
.x ring the turbine control to the alternative control location,s
- HPCI. operation will. rely' solely on operator action for HPCIj ll startup,. flow control, shutdown and instrument monitoring.
air-operatefj For.
the HPCI alternative control
- method, no valve. is considered. essential for HPCI operation.
Electrical 7 c
n operation of the motor-operated valve for' isolation of the steamp P!
exhaust ~ vacuum breakers is not. considered essential for local m g:
- control ' operation If repetitive starts were to be necessary, i
L local valve realignment is assumed for this analysis.
3 0' HPCI Alternative Shutdown Modifications
.Several modifications are required ~to allow for local alter-c native control of HPCI in the event of. fires in the Control or L
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. Cable Spreading Rooms.
The proposed HPCI modifications are pre-sented below in accordance to the affected components:
o HPCI-Turbine Control and Power Circuitry Three cables that are essential for turbine speed con-trol and monitoring will be modified.
These cables are:
-ZB 2(3) Q1800 C Control Room Flow Controller Signal to the Turbine-Speed Controller
-ZB 2(3) Q1800 G 125V de power from Control Room to Turbine EGM.
-ZB 2(3) Q1800 D Turbine tachometer signal to Control Room indicator.
.The modifications will isolate and replace the Control Room controller signal by a local (alternate) flow controller, will provide an-alternate 125V de feed from the HPCI motor control.
- center, -and will allow transfer of the tachometer signal to the local (alternate) station.
o Gland Seal Condenser Vacuum and Condensate Pump.
Auxiliary Oil Pump and Turbine Drain Pot Solenoid Valve The control cables for these devices are presently routed from the HPCI Pump Room to the Cable Spreading Room.
This configuration will be changed so that these cables are first routed to the HPCI motor control center where electrical isolation and control transfer will be provided.
The cables of concern are:
ZB '2(3) a1801A and C, ZB 2(3) Q1802B, ZB 2(3)Q1803B, ZB 2Q1819A and B.
S E
- o HPCI Discharge Flow Transmitter The' HPCI discharge flow transmitter (FT23-82) instru-l ment cable is presently ' routed through the Cable Spreading Room to provide the flow input signal to the Page 6 L
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HPCI turbine flow controller circuitry in the Control Room.
This cable (ZB 2(3)Q1799T) will be rerouted so that. transfer to the alternate. local flow controller and associated instrumentation is performed at the alternate control location.
o HPCI Turbine Trip Solenoid The HPCI turbine auxiliary trip solenoid valve SV1 (mounted locally at the turbine skid) receives its control power signal from the Cable Spreading Room (cable ZB 2(3) Q1835A).
To avoid inadvertent trips the present cable route will be modified to allow isolation at the alternate control location.
o.
The HPCI main pump / turbine protection interlocks (low net positive suction head and high turbine exhaust pressure) will be wired to remain intact during periodic system tests.
However, transfer switches will be.provided at the alternate control location to iso-late these-signals during " post fire" operation.
The l
corresponding wiring will be isolated separately from the -remainder of the remote control cables for the purposes of - testing.
These interlocks will provide assurance. that inadvertent operator errors during testing will not damage the HPCI pump or turbine.
4.0 Response to NRC Generic Letter 81-12 The' attached list of essential HPCI components,- highlighted
'HPCI' Piping and Instrumentation Diagram. (Figure 7.4.1),
. Modification (preliminary) of M023-16 (drawing E-100) and HPCI Evaluation ' Diagram (drawing E-101) in combination with the HPCI I
system -description for alternative shutdown are deemed adequate
- in providing the information requested in selected portions of the NRC Generic Letter 81-12, dated February 20, 1981, Section 8 i
e of. Enclosure 1 and-Enclosure 2.
To ' clarify thisEposition, a preliminary response is pre-2 sented below for. selected information requests required for Staff review.
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74.1 Section 8
of Enclosure 1
to Generic Lettar 81 Information required for Staff Review a.
' Description. of the systems or portions thereof used to provide the shutdown capability and modifications re-quired to achieve the alternative shutdown capability if; required.
Response
A'priliminary HPCI system description for the alterna-tive shutdown 1 conditions is presented in section 2, in addition to a-summary of the proposed modifications (section 3).
A system description for the normal operation of HPCI will be included in the final report and can'be found in section 6 of the FSAR.
b.
System. design by drawings which show normal and alter-nate shutdown. control and power circuits, location of components, and that wiring which is in the area and
. iring which is out of the area that required the the w
alternative system.
Response
The attached highlighted HPCI P&ID coupled with the HPCI Evaluation Diagram and HPCI alternate shutdown vital equip-ment list depict'all the'information being requested.
d.
. Demonstrate that wiring, including power sources for
-the control circuit:and equipment operation for the alternate shutdown method, is independent of equipment wiring in the area to be avoided.
Response
The attached HPCI Evaluation Diagram indicates the power-and: control wiring which will be active during alternative-shutdown operation.
No power or control wiring routed within the
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Control ' Room or Cable Spreading Room will be electrically con-nected to the-active alternate shutdown. HPCI circuits after
. transfer. switches are.in their " local" position.
This will be
. accomplished by electrically isolatinr 'll HPCI control wiring of the. essential. HPCI components-at the C Motor Control Centers l(20D11 and 30D11 for units 2&3 respectively).
e.
Demonstrate that alternate shutdown power
- sources, including'all breakers, thave isolation devices on-con-
. trol' circuits that are routed through the area to be
. avoided,
.even-if the breaker is to be operated
. manually.
Responses i:e Evaluation Diagram indicates that the normal power Page 8 n_,.___-
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t source ~ for the HPCI MCC is independent of the two areas of con-cern.
Furthermore, all HPCI control circuits will be provided with.125V do control power-circuit breakers at the individual MCC cubicles to avoid fuse replacement.
f.
Demon;' ' ate that spare fuses are available for control circuits where these fuses may be required in supplying
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power to control circuits used for the shutdown method and may. be blown by the effects of a cable spreading
.rcom fire.
.The spare fuses should be located conven-
'ient to the existing fuses.
The shutdown procedure should inform the operator to check the fuses.
Response: The attached typicai circuit schematic modification for the.HPCI motor-operated valve MO 23-16 depicts the addition of a circuit breaker-in the control circuit to replace the existing control power fuse.
Such an arrangement will be used for all the modified' MCC' control. circuits.
For other HPCI control circuits (for example the local turbine flow controller instrument loop),
separately fused alternate control power sources will be provided on_ required alternate shutdown circuits.
The portions of the circuits located outside the Control and Cable Spreading Rooms are. protected against fire included faults inside the areas by
- the normal' control power fuses.
.To shift plant operation to the
- alternate control station, transfer switches are manipulated in the required' circuits _to. disconnect the potentially blown fuses and faulted cable.
-The same switches, using break-before-make
- contacts, then tie' in the alternate fuses. and control power sources.
.This scheme eliminates the need for spare fuses during the shutdown process.
4.1 of Generic Letter 81-12 Request for
' Additional Information
.For-each fire area where an alternative or dedicated shut-
'down method, in accordance with Section III.G.3 of Appendix R to 10-CFR Part 50, is provided by. proposed modifications, the fol-
. lowing l information is required to demonstrate that associated circuits will not prevent operation or cause maloperation of the alternative or dedicated shutdown method:
Ja.-
. Provide a
table that lists all equipment including instrumentation and support system equipment that are required by the alternative or dedicated method of Page 9 1
______________.____i__________z__..m_______
.a n achieving and maintaining hot shutdown.
b.
.For each alternative shutdown equipment listed in a.
.above, provide a table that lists the essential cables (instrumentation, control, and power) that are located in the fire area.
c.
, Provide'.a-table that lists safety-related and non-safety-related. cables associated with the equipment and cables constituting the alternative or dedicated method of shutdown.that are located in the fire area.
.x_
d.
Show that fire-induced failures of the cables listed in b.
and c.
above will not prevent operation or cause
-maloperation of the alternative or dedicated shutdown method.
e.
For each cable listed in b.
- above, provide detailed
- electrical schematic drawings that show how each cable is isolated from the fire area.
Responses a.
& b.t.
This request is considered adequately fulfilled by the information provided in the evaluation diagrams coupled with the list-.of.HPCI vital equipment and highlighted P&ID' presented on a safe shutdown system basis..
c.
'& d :
The information' depicted for the various safe shutdown systems in the Evaluation Diagram include all components which are' essential for system operation and the corresponding
- power, control and instrumentation cables, electrical distribution and
- control. panels, and the location of all equipment above
-(including cables).
With respect to the' potential threat to the alternative shutdown capability from associated circuit
- cables, the analysis of the HPCI Evaluation Diagram for a postulated fire in the two areas of concern is described below.
o-Circuits Associated with HPCI Alternative Shutdown-by Spurious-Operation:
2:eludingmtheMissuemofchigh/lownpressurea interface
'b~etweenuttheimromet6F306Ishti syst' sin dfaridTot6eF16wer8 desi 6F6?sysfe5 emf 6hrarer treated = sepaFstilVP
.66"^gaz pretispurious circuits exist associated with HPCI since
- the component'and cable selection process did not ex-clude-components nor logic / instrumentation interlocks which. have a
functional impact on HPCI operation.
.Thus, the definition of alternative shutdown control f oexx i&PC In is s based x onsisola t i ons o f r all' oontro lm aa bles w
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- which are known to be dependent on the areas of concern t
and that could carry erroneous (fire-induced) commands to the HPCI local components.
o Circuits Associated with HPCI Alternative Shutdown by Common Power Sources:
Modifications will be provided so that the turbine and flow control circuitry will receive alternate shutdown power at the HPCI motor control center-(existing cir-cuitry is. dependent upon the Control and Cable Spreading Rooms).
Thus, the only common power sources will be the HPCI motor control center, the batteries B/D, and the main 250/125 V de distribution panels in the Battery Room.
S ince-alL. load s -at -t he se e d i a t r i bi28 tion,, centers-are-adequately = protected:+and*"coordi6ated" ibEf uses,-pao,oable -f a ilure* wi thin u the c arle(((!o fic on~c d6*"
shouldw= result==in-HPCI" alternate ~ shutdown poweg_, loss
-(125/250 V do).
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o Circuits Associated with HPCI Alternative Shutdown by Common
Enclosures:
No high voltage (4.kV ac and above) or medium voltage (480V ac) cables are routed within the areas of concern
'(Cable Spreading and Control Rooms) except-for the 480 volt ac feed to the computer HVAC which is routed in the Cable _ Spreading Room in its own conduit.
Fire-induced short circuit currents could only affect 125V do and 120V'ac control power cables being routed in the two areas of concern.
For these two types of' control
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power: circuits,.the power distribution panels are either at'the-Cable Spreading Room / Control Room or at
' local motor control centers.
Fire-induced faults in control power _ cables routedEin the two areas of concern for which the power distribution panels are in the same areas: '(Control. and Cable Spreading Rooms) will not propagate outside_the Cable Spreading Room and will be cleared by the protective' devices provided at these panels.
Fire-induced faults in' control cables of local motor-control centers will be cleared at the motor control' centers since'the control circuit for each load is individually fused by design.
cables are located in the Reactor Building and Radwaste @p Since-the -HPCI alternative shutdown equipment and Building one or more rated fire-barriers exist between d
'che areas of concern and the HPCI alternative shutdown B enclosures (motor center & raceways), thusprovidingcn@
adequate measure to prevent' propagation of the
'ostu-@
lated fires.
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