ML20246P256
| ML20246P256 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 07/31/1989 |
| From: | LOUISIANA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20246P244 | List: |
| References | |
| NUDOCS 8907200140 | |
| Download: ML20246P256 (46) | |
Text
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S-WATERFORD STEAM ELECTRIC STATION - UNIT NO. 3 COMPLIANCE WITH 10CFR50.62 REDUCTION OF RISK FROM ANTICIPATED TRANSIENTS WITHOUT SCRAM EVENTS JULY, 1989 1
NSIO0283E
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l' TABLE OF CONTENTS 1.
Introduction 2.
Diverse Reactor Trip System
.A.
Functional Description B.
System Interfaces c.
Details of Operation D.
Annunciation E.
Test Capabilities 3.
Diverse Emergency Feedwater Actuation System A.
Functional Description B.
System Interfaces C.
Details of Operation D.
Annunciation E.
Test Capabilities 4.
Diverse Turbine Trip (DTT)
A.
Functional Description
.3.
System Interface and Acceptance 5.
Design Compliance with NRC Guidelines for 10CER50.62 (ATWS) Rule 6.
Components & Qualifications 7.
Revised Responses to the NRC December 20, 1988 Request for Additional Information (RAI) 8.
Figures i
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1 NS100283E
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_ _ _ _ _ = _ - _ - _ _ - - - - - -
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l1e 1.
INTRODUCTION-NS100283E
______-._____a
l L
1.
Introduction This - report was prepared to provide a revised functional design of a Diverse Reactor Trip System (DRTS), formerly referred to as the Diverse Scram System (DSS),
Diverse Turbine Trip (DTT) and a pro-a l
i posed design of a Diverse Emergency Feedwater Actuation System (DEFAS).
The design information in this report supersedes the information in the October, 1988 (W3P88-1916) submittal and. the responses to the Decem-ber, 1988 RAI.
1 The functional design of the DRTS, the DTT and.the DEFAS was prepared in compli.ance with requirements of 10CFR50.62. The Diverse systems are independent of the presently installed Plant. Protection System (PPS) that consists of Reactor Trip System (RTS) and Engineered Safety Fea-tures Actuation System (ESFAS).
The root cause of the ATWS is considered to be generated within the PPS panel and be of a passive or active nature.
The passive nature of an ATWS would consist of a fault in the PPS that would prevent PPS from initiating the protective actions for which it is designed, such as trip of the reactor and/or actuation of emergency feedwater system, when need for such actions is required as a l
consequence of a normal operational occurrence in the plant, such as l
loss of normal feedwater flow, etc.
The active nature of an ATWS would consist of a fault in the PPS that would - result in an inadvertent actuation of MSIS preventing emergency -
feedwater flow to the steam generators.
The inadvertent actuation of the engineered safeguard systems may or may not be accompanied by the automatic trip of the reatior.
The DRTS, the DTT and the DEFAS are eLle to respond to an ATWS event caused either by passive (failure to act) or by active (random action) failures in the PPS.
The condition indicative of an ATWS was chosen to be the presence of a,
higher pressure in the primary loop than is required for the RTS trip of the reactor.
It is assumed that there is no seismic event or significant plant physical damage concurrent with ATWS.
The power supplies are capable of performing their required design functions upon Loss of Off Site Power.
NS100283E ______ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _
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j
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2.
DIVERSE REACTOP. TRIP SYSTEM A.
Functional Description B.
System Interfaces C.
Details of Operation
,l I
D.
Annunciation E.
Test Capabilities
(
l l
NS100283E
.l
p p
L 2.
Diverse Reactor Trip System (URTS)
A.
Functional Description The purpose of the DETS is to provide equipment to comply with the.
10CFR50.62 requirement for a diverse mear 2 of removing' power from the reactor control rods mechanism and consequently to initiate the reactor trip. The DRTS monitoring and actuation devices are inde-pendent of the Plant Protection System.
The Diverse Reactor Trip System (DRTS) is a dual channel system.
It consists of pressure censors in the pressurizer, a selector switch and two push buttons on the main control board, a control room annunciator, and ' relay logic as depicted in Figures 1 and 2.
The initiation signal for the DRTS is high pressure in the pres-surizer. The pressurizer pressure parameter is monitored by two dedicated transmitters.
The signal from each transmitter is fed to the analog to digital (A/D) converter with a setpoint of approximately 2435 psig as compared to the RTS trip setpoint of 2350 psia and allowable value of 2372 psia.
The output contact of both A/D converters are wired into a two-out-of-two logic configuration used to de-energize e holding coil of the. motor-generator set output contactors.
The Reactor Trip Switchgear is powered by two sets of motor gener-ators (MGs) connected in parallel with two output contactors in the feeder lines to the Reactor Trip Switchgear. The MG set out-put contactors are held in clos'ed position by the energized holding coils.
De-energization of the holding : oils will cause the opening of the MG set output contactors and cor.sequently trip the reactor.
Two push buttons are inct died on the main control board to provide the means of manual initiation of the DRTS. The contacts of these two push buttons are wired in the same configuration as the contacts of the A/D converter.
Depressing both push buttons simultaneously will result in de-energizatlon on the MG set output contactor coils and subsequently trip the reactor.
A two position selector switch is provided on the main control board to provide the operator with means of enabling or disabling the operation of DRTS.
When the selector switch is in the
" Disable" position, neither the A/D converter contacts nor the push buttons can initiate a reactor trip.
NS100283E. - - _ - - _ _ _ _ _ _ _ - _ _ _ _ _ - - _ _ - _ _ _ _
1I;.
4-2.
Diverse Reactor Trip System (DRTS)
(Con' d)
B.-
System Interface The DRTS uses two Class IE pressure transmitters to monitor the pressurizer pressure.
One pressure transmitter is installed in safety channel SA and is connected to the Process Analog Control-(PAC) panel LCP-61.
The second pressure transmitter is int,talled in safety channel SB and is connected to PAC panel LCP-62.
The pressurizer pressure instrumentation loops in the PAC panels LCP-61 and LCP-62 are identical, each consisting of the following Westinghouse, Class IE, process cards:
a.
Channel Test Card NCTI.
b.
Loop Power Supply with Isolated Output Card NLP2.
c.
Signal Isolator Card NLP3.
All cards have been qualified for use in the Class 1E, safety related circuits.
Cards NLP2 provide the isolated signals from safety channel SA to prctective channel SMC and from safety channel SB to protective channel SMD for the wide range pressurizer pressure inputs to QSPDS-1 and QSPDS-2, in compliance with Regulatory Guide 1.97.
Cards NLP3 provide the isolated signals from safety channels SA and SB to the A/D converters in non-safety channel NS.for initiation of the DRTS.
The DRTS relay logic including the MG set outpt,. contactor are within the non-safety channel NS.
C.
Details of Operation The DRTS is depicted in Figures 1 and 2.
Pressure transmitters PT-RC-9120A and PT-RC-9120B are continuously monitoring pres-surizer pressure.
The pressure signal is processed in the exist-ing PAC Panels LCP-61 and LCP-62.
The instrumentation loops of I
pressure transmitters PT-RC-9120A and PT-RC-9120B are located within the Class 1E safety channels SA and SB respectively and are l
provided with Westinghouse type NLP3 isolator cards for interface with analog to digital (A/D) converters RPHA and RPHB ti.it are loca *d in the non-safety channel NS.
The isolator card NLP3 output signal is 0-10VDC corresponding to the pressure range of 0 - 4000 psig.
The isolator output signal from PAC panel LCP-61 is connected to A/D converter RPHA and j
provides the interface between safety channel SA and non-safety 1
channel NS.
The isolator output signal from PAC panel LCP-62 is connected to A/D converter RPHB and provides an interface between the safety channel SB and the non-safety channel NS.
NS100283E _ ____-_____ _ _ ___- _____ ___ ___- _ _
2.
Diverse Reactor. Trip System (DRTS)
(Cont'd)
C.
Details of Operation (Con *'d) l 3
The A/D converters are provided with two adjustable setpoints with ll corresponding output contacts I
The first setpoint.(SP1) is set at 6.087V DC, corresponding to the pressurizer pressure of approximately 2435 psig.
The Normally Open (N.O.) contact of SP1 is in closed position when the input I
signal is of a higher value than the setpoint and the A/D converter is energized.
The SP1 contact is used to recognize the ATWS con-dition in the plant and to initiate the bRTS relay logic.
The pressurizer pressure trip setpoint for DRTS is selected such that it is greater than the RPS High Pressurizer Pressure Trip setpoint (HPPTS) and less than the Primary Safety Valve. (PSV) set pressure of 2500 psia ( 1%).
The DRTS HPPTS is greater than the -
existing RTS HPPTS in order to avoid unnecessary reactor trips.
The DRTS HPPTS is less than the minimum PSV set pressure in order to prevent a delay in the generation of a trip signal caused by the opening of the PSVs.
The second setpoint (SP2)'is set at a minimum value of the input signal.
The N.O.
contact of SP2 is in the closed position when the input signal is present and A/D converter is energized.
The SP2 contact is used to initiate an alarm annunciator on loss of input signal or power supply to the A/D. converter.
The SP1 contact in A/D converter RPHA is connected to the coil of relay TA.
The SP1 contact in A/D converter RPHB is connected to the coil of relay TB.
Two push buttons (PB-A and PB-B) are provided on the main control board for manual initiation of DRTS. The N.O. contact of PB-A is connected to the coil of relay TA and the N.O. contact of PB-B is connected to the coil of relay TB.
A two position " Enable-Disable", maintained contact, selector switch (SS) is provided on the main control board to allow the operator to enable or disable the operation of the ?RTS.
The selector switch is provided with four indicating lights-green, red, and two whites.
The " Disable" position contact of the SS is connected to the reset coil of the latching relay TP and the
" Enable" position contact of the SS is connected to the operating coil of the latching relay TP.
The green and red lights are continuously monitoring and verifying the correct position of the latching relay TP.
The white lights indicate that the DRTS actuation relay TA or TB is energized.
NS100283E _
2.
Diverse Reactor Trip System (DRTS)
(Cont'd)
C.
Details of Operation (Cont'd)
The actuation of DRTS is performed only when the selector switch
~i SS is selected for the " Enable" position. With selector switch SS I
in the " Enable" position, the coils of relays TA.and TB seal in, through their contacts TA and TB in series with contacts of contacts of either A/D latching relay TP, when energized by' converters or push buttons.
1 l
1 Two sets of Normally Closed (N.C.) contacts of relays TA, TB, and TP, wired in parallel, constitute the DRTS actuator.
All three contacts must be in open position to actuate the DRTS.
Contacts TA and TB open when the two-out-of-two condition for initiation of the DRTS is satisfied.
Contact IP is open when the selector switch SS is selected for the " Enable" position.
Once the DRTS attuator contacts are opened, they will remain in the open position until the ATWS high pressure condition subsides and in the DRTS actuation relay logic is disabled by selection of the " Disable" position on the selector switch SS.
Each set of DRTS actuator contacts is wired into the control.
circuit of each MG set output contactor.
When all DRTS actuator contacts open, the current to the holding coil 3-CON (Figure 5) of the MG set output contactor is interrupted resulting in opening of the output contactor.
The opening of both MG set output contact-ors will interrupt the power flow to the reactor control element assemblies and cause the reactor to tcip.
D.
Annunciation The alarm annunciator circuit is shown in Figure 1.
The contacts of relay TP in the alarm circuits are shown with relay TP in a reset position and the selector switch in the " Disable" position.
The operation of two DRTS related alarm annunciator windows is as described below:
1.
Annunciator window engraving.
DIVERSE REACTOR TRIP ACTIVE / TROUBLE The alarm annunciator shall be actuated under the following conditions:
a.
DRTS is disabled and one or two DRTS initiation signals are present.
(Contacts TA and/or TB open).
NS100283E _____-_ _
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2.
Diverse Reactor Trip System (DRTS)
(Cont'd)
D.
Annunciation (Cont'd) b.
DRTS is enabled and one out of two DRTS initiation-signal is present.
(Contact TA or TB open).
c.
DRTS is enabled and the control power ta DRTS relay logic is lost or one or both input signals to A/D converters are lost.
(Contact RPHA-SP2 and/or RPHB-SP2 open.)
l 2.
Annunciator window engraving.
DIVERSE l
REACTOR TRIP The alarm annunciator shall be actuated under the following condition.
a.
DRTS is enabled and both DRTS initiation signals are present.
(Contacts TA and TB open).
E.
Test Capabilities The. test of pressure transmitters PT-RC-9120A and PT-RC-9120B primary instrumentation loops is performed in accordance with existing procedures for testing of Class IE instrumentation loops.
A.
The test of the primary instrumentation loops and the DRTS relay logic can be performed during plant operation.
The test is performed in the following steps:
1.
Place the selector switch SS into the "Di s able" position.
2.
Increase the signal in PT-RC-9210A primary instrumentation loop until the output signal to A/D converter PRHA equals the setpoint SP1 value.
The contact RPHA-SP1 will close to energize the relay coil TA.
The contact of relay TA will close to energize the white indicating lights on selector switch SS.
" DIVERSE REACTOR TRIP ACTIVE / TROUBLE" alarm will be annunciated.
3.
With _ input signal to A/D converter RPHA being below the setpoint SP1 value, depress push button PB-A.
Push button PB-A contact will close to energize the relay coil TA. The contact of relay TA will close to energize the white indicating lights on selector switch SS.
" DIVERSE REACTOR TRIP ACTIVE / TROUBLE alarm will be annunciated.
NS100283E _ _ _ _ _ _ _ _ _ _ _ _ _ - _
2.
Diver.se Reactor Trip System (DRTS)
(Cont'd)
E.
Test Capabilities (Cont'd) 4.
Place the selector switch SS into the " Enable"' position.
5.
Decrease the signal in PT-RC-9120A primary instruments-tion loop until - the output. signal to A/D converter RPHA is below the setpoint SP2 value.
The contact RPHA-SP2 will open and the " DIVERSE REACTOR TRIP ACTIVE / TROUBLE" alarm will annunciate.
6.
Repeat steps - 1 and 5 for the. operational test of the DRTS relay TB.
7.
The operation of relay TP is monitored continuously by
~ indicating green and red lights on the selector switch SS.
B.
The operational test of the MG set output contactors is performed when the plant is in the shutdown condition only.
The test is performed in the following steps:
1.
Place the selector switch SS into the " Enable" position.
2.
Depress both push buttons PB-A and PB-B to. energize relay coils TA and TB simultaneously.
The contacts of relays TA and TB will open to de-energize the holding coils of both MG set output _ contactors.
Also, the contacts of relays TA and TB will close to energize the white indicating lights on the selector switch SS.
The
" Diverse Reactor Trip" alarm will annunciate.
3.
Ascertain the operation of the MG set output contactors at the MG set local control panel.
4.
Turn the selector switch SS to the " Disable" position to unseal relays TA and TB.
The white lights at the selector switch will go off.
NS100283E _ _ _ _ - _
I 1
i 3.
DIVERSE EMERGENCY FEEDWATER ACTUATION SYSTEM A.
Functional Description
-B.
System Interfaces C.
Details of Operation D.
Annunciation l
E.
Test capabilities l
i NS100283E
3.
Diverse Emergency Feedwater Actuation System (DEFAS)
A.
Functional Description The purpose of DEFAS is te orovide aqu!cment' to comply with the 10CFR50.62 requirement for a ' diverse means of actuation' of Emer-gency Feedwater system.
The DEFAS monitoring and actuation devices are independent of the Plant Protection System.
The Diverse Emergency Feedwater Actuation System (DEFAS) is depicted on the Figures 3 Sh. I and 2 and consists of the following:
1.
Steam generator A and B level signals derived from the existing Class 1E instrumentation loops.
2.
Interlock with DRTS within the non-safety related channel NS.
3.
Two position selector switch and two. push buttons mounted on the non-safety related portion of the main control panel.
4.
Relay logic and annunciator circuits in the non-safety related channel NS.
5.
Isolation relays between non-safety channel NS and safety channels SA and SB.
6.
Steam generator A and B pressure signals derived from the existing Class IE instrumentation loops.
7.
Interlocks with Emergency Feedwater System within Class IE safety channels SA and SB.
8.
Emergency Feedwater Equipment operating relays in safety channels SA and SB.
The initiation signal for the DEFAS is a two-out-of-two logic con'" uration of low level signals in both steam generators. The low level signals are derived from the wide range level instrumentation loops that are an integral part of the existing Emergency Feedwater Control System (EFCS).
The level signals from safety channels SA and SB of each steam generator are fed to the analog to digital (A/D) converters with a setpoint of 55% of the wide range.
The 55% value corresponds to the critical level in the steam generators. The critical level in the steam generators was established to deter-mine the quantitative requirements for the emergency feedwater influx to the steam generators and is used as a starting point in the operation of the existing emergency feedwater control system.
NS100283E,
3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd)
.A.
Functional Description (Cont'd)
The output contacts of A/D converters associated with the same safety' channel parameters in both steam generators are wired into a-two-out-of-two logic configuration and are interlocked with the DRTS actuator contacts to limit the function of the DEFAS to 'he events indicative of an ATWS.
A pair of isolation relays are provided to transfer the DEFAS initiation signals from non-safety related channel NS to safety channels SA and SB for actuation of emergency feedwater system equipment.
The DEFAS actuation signals are interlocked in each safety channel with the pressure parameters of each steam generator and with the EFAS.
The steam generators pressure parameters assist in identi-fying a spurious MSIS and are used as a permissive for actuation of the emergency feedwater system. The interlock with the EFAS is provided to ensure that the DEFAS actuates the emergency feedwater equipment only in case of EFAS failure.
Two push buttons are installed on the main control board to provide the means of r.anual initiation of the DEFAS. The contacts of these two push buttons are wired in the same configuration as the contacts of A/D converters.
Depressing both push buttons simultaneously will result in operation of both isolation relays and transfer of the DEFAS initiation signals to the DEFAS actuation relays in safety channels SA and SB.
A two position selector switch is provided on the main control board to provide the operator with a means of enabling or dis-abling the operation of the DEFAS. When the selector switch is in the " Disable" position, neither the A/D converter contacts nor the push buttons. are effective to initiate the actuation of the emer-gency feedwater system.
The coils of the DEFAS actuation relays are to be energized to actuate the emergency feed.ater system. The contacts of the DEFAS actuation relays are wired into the control circuits of the emer-gency feedwater equipment and perform the same control actions as the contacts of the EFAS.
These actions consist of the following:
1.
Start motor driven emergency feedwater pumps.
2.
Open steam valves to the turbine of the turbine driven emergency feedwater pump.
3.
Close steam generator steam blowdown valves.
4.
Open emergency feedwater isolation valves.
NS100283E e
3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd)-
A.
Functional Description (Cont'd) 5.
Release control of the emergency feedwater control valves to the existing EFAS.
The existing feedwater emergency control system regulates the initial flow of the emergency feedwater to the steam generators and subsequently maintains a preset level in the steam generators.
The emergency feedwater system will continue to function properly as long as the pressure in the steam generators remains above the setpoints of the steam generators pressure interlock signals and' consequently the DEFAS actuation relays. remain energized. As the cool down of the plant progresses, the pressure in steam generators will decrease and will approach the setpoint value of the steam generators pressure interlock signals.
At this point, operator intervention will be required to either bypass the DEFAS or manually lower the steam generator pressure interlock setpoints in order to ensure completion of the plant cool down.
B.
System Interfaces The steam generator low level signals that are used for initiation of DEFAS are derived from the existing emergency feedwater control system.
The emergency feedwater control system - consists of two independent safety channels SA and SB.
Each safety channel comprises one wide range level transmitter for each steam generator.
The safety channel SA instrumentation loops for steam generators 1 and 2 are located in the PAC panel LCP-61.
The safety channel SB instrumentation loops for Steam Generators 1 and 2 are located in the PAC panel LCP-62.
One Westinghouse signal isolator card NLP3 is added in each instrumentation loop (total 4) to - provide the isolation signals from the steam generator level monitoring instrumentation safety channels SA and SB to the A/D converters in the non-safety channel NS for initiation of DEFAS. The Westinghouse signal isolator card NLP3 is qualified for use in Class 1E circuits.
The DEFAS initiation relay logic is located within the non-safety related channel NS.
However, the DEFAS actuation relays are located within the same safety channels SA and SB as the emergency feedwater system equipment that they are actuating.
Two isolation relays, Electro Switch type CSR are used, one from channel NS to channel SA and the other from channel NS to channel SB, for transfer of the DEFAS initiation signals to the DEFAS i
actuation relays.
I The Electro Switch type CSR isolation relay is qualified for use in Class 1E circuits.
NS100283E <
3.
. Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
B.
System Interfaces (Cont'd)
The actuation of the DEFAS requires the permissive signals to assist in identifying a spurious MSIS.
These permissive signals are provided by the steam generator pressure parameters and are derived from the existing instrumentation loops.
Steam Generator No. I pressure monitors are located within the safety channel SA, and Steam Generator No. 2 pressure monitors are located within the safety channel SB.
In order to provide the steam generator pressure interlock signal from each steam generator to the DEFAS actuation relays in safety channels SA and SB, Electro Switch type CSR isolation relays are provided.
One isolation relay is used to transmit the Steam Generator No. I pressure interlock signal from safety channel SA to the DEFAS actuation relay in safety channel SB, the other isolation relay is used to transmit the Steam Generator No. 2 pressure interlock signal from safety channel SB to DEFAS actuation relay in safety channel SA.
The Electro Switch type CSR isolation relay is qualified for use in the Class 1E circuits.
C.
Details of Operation The DEFAS is depicted in Figure 3 Sh. I and 2.
The wide range level transmitters LT-FW1115AS and LT-FW1115BS are continuously monitoring the level of water in Steam Generator No.
1.
Wide range level transmitters LT-FW1125AS and LT-FW1125BS are continuously monitoring the level of water in Steam Generator No.
2.
The signals from level transmitters LT-FW1115AS and LT-FW1125AS are processed in PAC panel LCP-61, located within the safety channel SA.
The instrumentation loops of LT-FW1115AS and LT-FW1125AS are provided with Westinghouse type NLP3 isolator cards for interface with the A/D converters LIA and L2A respectively, located within the non-safety related channel NS.
The signals from level transmitters LT-FW1115BS and LT-FW1125BS are processed in the PAC panel LCP-62, located within the safety channel SB.
The instrumentation loops of LT-FW115BS and LT-FW1125BS are provided with Westinghouse type NLP 3 isolator cards for interface with the A/D converters L1B and L2B respectively, located in the non-safety related channel NS.
The isolator card NLP3 output signal is 0-10V DC corresponding to 0-100% of the wide range level measurement in the steam generator.
NS100283E 1 I
u
3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
C.
Details of Operation (Cont'd)
The A/D converters are provided with two adjustable setpoints' with corresponding output contacts.
The first setpoint (SP1) is set at 5.5V DC corresponding-to 55% of steam generator level. The N.0. contact of SP1 is closed when the input signal is below the setpoint and the A/D converter is energized.. The SP1 contacts are used to initiate the DEFAS relay logic.
The second setpoint (SP2) is set at a minimum value of the input-signal.
The N.O. contact of SP2 is closed when the input signal is above the setpoint and the A/D converter is energized. The SP2 contact is used to initiate an alarm annunciator on loss of input signal or loss of power supply to the A/D converter.
The SP1 contacts of A/D converters LIA and L2A and the contacts TP and TA from the DRTS relays are connected in series to the coil of the DEFAS initiation relay DFA.
The SP1 contacts of A/D converters LIB and L2B and the contacts TP and TB from the DRTS relays are connected in series to the coil of the DEFAS initiation relay DFB.
The DEFAS initiation relays DFA and DFB are energized to initiate the DEFAS when the following conditions are present:
1.
DRTS is actuated providing an indication that a condition indicative of ATWS exists.
2.
Low water level is detected in both steam generators by level monitodne devices of the Emergency Feedwater Control System in both safety channels SA and SB.
Two push buttons, PB-A and PB-B, are provided on the main control board for manual initiation of the DEFAS.
The N.0, contact of PB-A is connected to the coil of relay DFA and the N.0. contact of PB-B is connected to the coil of relay DFB.
A two position " Disable Enable", maintained contact, selector switch SS is provided on the main control board to allow the operator to enable or disable the operation of the DEFAS.
The selector switch SS is provided with four indicating lights; green, red, and two whites.
The " Disable" position contact of the SS is connected to the reset coil of the latching relay DFP and the
" Enable" position contact of the SS is connected to the operating coil of the latching relay DFP.
The white lights indicate that the DEFAS initiation relay DFA or DFB is energized.
NS100283E - - _ - _ _ - _ - - - - - _ - _ _ - - - - _ _ _ _ _
1
I L
3.
Diverse Emergency Feedwater Actuation System (DEFAS)-
(Cont'd.)
l C.
Details of Operation (Cont'd)
- The actuation of the DEFAS is performed only when the selector switch SS is selected for the " Enable" position.
With selector switch SS in the " Enable" position and DEFAS initiation relays DFA and DFB energized, the contacts of DFA and DFB energize the coils of isolation relays NSA and NSB.
The coils of the isolation relays, when. energized, seal in through their contacts NSA or NSB -
in series with the contact of latching relay DFP.
The isolation relays will remain in the picked up position providing a continuous DEFAS actuation signal to the DEFAS operating circuits in safety channels SA and SB until the selector switch SS is placed into the
" Disable" position.
The EFS equipment in the safety channel SA is actuated by DEFAS relays DFVA and DFPA.
1 The EFS equipment in the safety channel SB is actuated by DEFAS relays DFVB and DFPB.
In order to complete the DEFAS actuation of EFAS equipment, the following two conditions in the plant must be satisfied:
1.
Failure of the EFAS to operate.
The DEFAS is essentially duplicating actions of the EFAS on EFS equipment.
The actuation of the EFAS will negate the need for DEFAS.
2.
The pressure in both steam generators is above 800 psig.
The initial setpoint of 800 psig is selected to assist in identifying a spurious MSIS before the DEFAS is actuated. As the cool down of the plant progresses and the steam gene-rators pressure is decreasing, operator action will be re-quired to allow the completion of the plant cool down process using the steam generators.
The steam generators pressure permissive signals are obtained from the existing pressure monitoring instrumentation loops as des-cribed below:
The pressure transmitters PT-MS1115AS and PT-MS0303AS are continuously monitoring the pressure in the Steam Generator No.1.
The pressure parameter from the pressure transmitter PT-MS1115AS is monitored in PAC panel LCF-61 and the pressure parameter from the pressure transmitter PT-MS0303AS is monitored in PAC panel CP-42.
NS100283E --___-_.. _ _
3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
C.
Details of Operation (Cont'd)
The instrument loops of the pressure transmitters are located within the safety channel SA and are provided with Westinghouse NAC1 and NC01 cards type 2838A32G01 and 2839A42001, respectively.
The N.O. output contacts on the NC01 cards. are closed when. the pressure parameter signal is above the setpoint e lue on the NAC1 card.
The output contacts from both NC01 cards in the safety channel SA are wired in series and are connected to the coil of isolation-relay P1AB.
The isolation relay provides the Steam Generator No.
I pressure permissive interlock contacts in the safety channels SA and SB.
The pressure transmitters PT-MS-1125BS and PT-MS0303BS are continuously monitoring the pressure in the Steam Generator No. 2.
The pressure parameter from the pressure transmitter PT-MS1125BS is monitored in PAC panel LCP-62 and the pressure parameter from the pressure transmitter PT-MS0303BS is monitored in PAC panel CP-45.
The instrument loops of both pressure transmitters are located within safety channel SB and are provided with Westinghouse NACI and NC01 cards type 2838A32G01 and 2839A42001, respectively. The N.O. output contacts on these cards are closed when the pressure parameter signal is above the setpoint value.
The output contacts from both NC01 cards in the safety channel SB are wired in series and are connected to the coil of isolation relay P2BA.
The isolation relay provides Steam Generator No. 2 pressure permissive contacts in safety channels SB and SA.
Contacts PIAB and P2BA, wired in series with the DEFAS operating relays DFVA and DFPA in the safety channel SA and in series with the DEFAS operating relays DFVB and DFPB in the safety channel SB, provide the required permissive signal of steam generators being intact for the actuation of EFS equipment by the DEFAS.
A test selector switch is provided in each of the safety channels SA and SB on the main control board for testing of the DEFAS actuation of EFS equipment.
NS100283E !
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3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
C.
Details of Operation (Cont'd)
The wiring of contacts of the DEFAS operating relays DFVA, DFPA, DFVB and DFPB in the control circuits of the emergency feedwater system equipnent is shown on the Control Wiring Diagram (Dwg. No.
-LOU-1564-B-424) sheet as tabulated below:
RELAY DFVA EQUIPMENT SH. 1546 SG No. 1 Emerg FW Isolation VLv 2FW-V848A SH. 1548 SG No. 2 Emerg FW Isolation VLv.2FW-V849A SH. 1551 SG No. 1 Emerg FW Control VLv 2FW-852A & FW-851B SH. 1552 SG No. 2 Emerg FW Control VLv 2FW-853A & FW-854B RELAY DFPA EQUIPMENT SH. 1535 Emerg FW Pump Turbine Stm Shut-off VLv 2MS-V611A
)
SH. 1560 SG No. 1 Blowdown Control Isolation VLv 2BD-F-603
& 2BD-F604 SH. 1565 SG No. 2 Blowdown Control Isolation VLv 2ED-F-605
& 2BD-F606 SH. 2343 EFW Motor Sequencer RELAY DFVB EQUIPMENT SH. 1547 SG No. 1 Emerg FW Isolation VLv 2FW-F847B SH. 1549 SG No. 2 Emerg FW Isolation VLv 2FW-F850B SH. 1551 SG No. 1 Emerg FW Control VLv 2FW-852A & 2FW-851B SH. 1552 SG No. 2 Emerg FW Control VLv 2FW-853A & 2FW-854B RELAY DFPB EQUIPMENT SH. 1536 Emerg FW Pump Turbine Stm Shut-off VLv 2MS-V612B SH. 1560 SG No. 1 Blowdown Cont Isolation VLys 2BD-F603 &
2BD-F604 SH. 1565 SG No. 2 Blowdown Cont Isolation VLvs 2BD-F605 &
2BD-F606 SH. 2393 EFW Motor Sequencer D.
Annunciation The alarm annunciator circuit is shown in Figure 3 Sh.
1.
The contacts of relay DFP, in the alarm circuits, are shown with relay DFP in a reset position, with selector switch SS being in the
" Disable" position.
NS100283E.. _ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ _ -
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3.
Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
L D.
Annunciation (Cont'd)
The operation of two DEFAS related alarm windows is described below:
)
1.
Annunciator Window Engraving.
DIVERSE EMERG FW ACTIVE / TROUBLE i
j The alarm annunciator shall be activated under the following conditions:
a.
DEFAS is disabled and one or two DEFAS initiation signals are present (Contacts DFA and/or DFB open) b.
DEFAS is enabled and one' out of. two DEFAS initiation signals is present. (Contact DFA or DFB open) c.
DEFAS is enabled and the control power to the DEFAS relay logic is lost or at least one input signal to the A/D converters is lost. (At least one contact in the series of LIA-SP2, L2A-SP2, LIB-SP2, L2B-SP2 contacts is open) 2.
Annunciator Window Engraving.
DIVERSE EMERG FW ACTUATED The alarm annunciator shall be actuated under the following conditions.
a.
DEFAS is enabled and both DEFAS initiation signals are present. (Contacts NSA and NSB open)
E.
Test Capabilities The test of DEFAS can be performed during the plant operation.
The DEFAS circuit consists of non-safety related relay logic used for initiation of EEFAS and two safety channels SA and SB with operational relays for the DEFAS actuation of emergency feedwater system equipment.
NS100283E -
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Diverse Emergency Feedwater Actuation System (DEFAS)
(Cont'd.)
E.
Test Capabilities (Cont'd) 1.
Test of non-safety relay logic To perform the test on the non-safety related relay logic, place the selector switch SS into the " Disable" position.
Vary the input signal -to each A/D converter (LIA, L2A, LIB, L2B) and observe that the output contacts-SP1 are open when the input signal is above the setpoint SP1 value and close when the input signal decreases below the setuoint SP1 value.
11pon depressing push buttons PB-A, relay DFA will be energized and contact DFA will close to energize white lights on the selector switch SS.
2.
Test of DEFAS Actuation of Emergency Feedwater Equipment A four position "0FF" Pumps / Blowdown Valves - Normal EFW Valves", maintained contact, test switch is provided in each safety related channel SA and SB of DEFAS for performance of the emergency feedwater equipment operational test.
To perform the DEFAS actuation of emergency feedwater equipment test, place the selector switch into the " Enable" position.
When the DEFAS actuation of safety channel SA is tested always place the test switch TS-B, in safety channel SB, into the "0FF" position.
When the DEFAS actuation of safety channel SB is tested always place the test switch TS-A, in safety channel SA into the "0FF" position.
With the test switch in the safety channel under test select the group of equipment to be tested. Simultaneously press both DEFAS initiation push buttons PB-A and PB-B.
This will energize and seal-in the isolation relays NSA and NSB, activate the " DIVERSE EMERG FW ACTUATED" alarm window, and energize the selected opera-tional relay.
If " Pumps / Blowdown Valves" position is selected on TS-A, the operational relay DFPA will be energized.
If "EFW Valves" position is selected on TS-A, the operational relay DFVA will be energized.
If " Pumps / Blowdown Valves" position is selected on TS-B, the operational relay DFPB will be energized.
If "EFW Valves" position is selected on TS-B, the operational relay DFVB will be energized.
NS100283E - _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
I.
3.
Diverse Emurgency Feedwater Actuation System (DEFAS)
(Cont'd.)
l E.
Test Capabilities (Cont'd) 1 i
The contacts. of the energized operation relay willy actuate the associated equipment (pump or valve but not both).
Hence this condition will not initiate the flow of emergency feedwater to the:
Turn the selector switch to the " Disable" position.
This.will' reset alarm circuits, unseal the isolation relays, and de-energize the DEFAS operational relay.
To confirm the equipment operation, the operator will follow the existing procedures for the actuation of emergency feedwater equipment by EFAS relays.
The complete test of DEFAS actuation of emergency feedwater equipment consists of four identical steps as described above.
It is imperative that the selector switch be turned to the " Disable" pcsition and all equipinent actuated by the preceeding step in test sequence be brought manually to the normal status before the next step in testing sequence is commenced.
4 NS100283E.....
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4.
DIVERSE TURBINE TRIP (DTT)
A.
Functional Description B.
System Interface and Acceptance NS100283E
i.
4.
Diverse Turbine Trip-(DTT)
A.
Functional Description Under normal operation, the turbine trip is initiate 6 in response to the RTS trip signal.
Since the ATWS design is based on the l
failure of. a RTS to trip the reactor, the omission of a turbine trip signal condition is evident. The DTT for Waterford 3 assures initiation of a turbine trip during an ATWS event.
The existing TT system initiates on a signal from the existing RTS.
By implementing a DRTS, an inherent DTT system is provided.
(See Figures 1, 2, 5, 6, and 7).
When the DRTS causes a reactor trip, power is interrupted to the control element drive mechanism coils upstream of the rod power bus undervoltage relays in the Control Element Drive. Mechanism Control System (CEDMCS).
De-energizing these undervoltage relays actuates the turbine trip circuitry.
Therefore in defining a DRTS (covered in Section 2 of I
this report), the existing TT is also diverse due to the diversity between the DRTS and the existing RTS.
Basically the system works via three phase power separately input to each of the CEDMCS undervoltage circuits, housed in separated cabinets.
Each circuit has the three phase power input monitored for an undervoltage condition by two redundant. undervoltage relays, which are part of an Undervoltage and Auxiliary Relay Assembly.
Each assembly, two per CEDM power bus, contains an undervoltage relay and two interconnected auxiliary relays.
Instrument bus power is used to energize the auxiliary relays.
Each undervoltage relay provides local indication of an undervoltage condition.
Remote annunciation is provided by auxiliary - relays, each of which is controlled by its interconnected undervoltage relay.
A second auxiliar'; relay is provided for testing each undervoltage/ auxiliary relay combination.
If the line-to-neutral voltage of any phase drops to 111 i 15 VAC input to the undervoltage
- relays, the relays de-energize.
De-energidug the undervoltage relays also de-energizes their interconnected auxiliary relays, which causes the associated turbine trip solenoid to energize resulting in a turbine trip.
This dependence of the DTT upon the DRTS means the operating statur f.'
the DRTS will reflect the operating status of the DTT.
Consequently, the control room annunciators will relay the status of the DTT.
NS100283E I i
4.
Diverse Turbine Trip (DTT)
(Cont'd)
B.
System Interface Acceptance The DTT system is an extension of the DRTS.
Tnere are no new components associated with - the DTT system that did not exist previously as part of the DRTS.
In this regard, the same level of acceptability. to each of the 11' areas of guidance for the DRTS of Section 5 directly applies to the DTT.
As required by the ATWS Rule, the Waterford 3 DTT establishes diversity from sensors to, but not including, the final actuation
. device to minimize the potential for common cause failure.
Like the DRTS design, the Waterford 3 DTT design meets or exceeds the.
guidelines suggested by the NRC.
Therefore adequate diversity-between the DTT and the RTS exists in compliance with the ATWS Rule.
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5.
DESIGN COMPLIANCE WJTH NRC GUIDELINES FOR 10CFR50.62 (ATWS) RULE NS100283E
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5.
. Design Compliance with NRC Guidelines for 10CFR50.62 (ATWS) Rule-The Waterford-3 DRTS and DEFAS meet the Federal Register ATWS l.
mitigating system guidelines as described below:
1.
Safety Related (IEEE 279)
The DRTS and DEFAS are non-safety related control-grade systems.
They are isolated from Class IE circuits with Class IE isolation devices so that they will not degrade safety related equipment and systems. The implementation of the DRTS and the DEFAS is such that the existing Plant Protection System (PPS) continues to meet-all applicable safety related criteria.
2.
Redundancy Redundancy is not required.
3.
Diversity form Existing Reactor Trip Systern The equipment used in the design of the DRTS and DEFAS are diverse from the existing PPS.
Pressurizer pressure instrumentation is used as input to the DRTS.
The DRTS output signals interface with the existing control circuit of the motor generator (MG) set output contactors.
The relays to the MG sets are divers-e (different manufacturer) from the relays used in the RTS.
The steam generator level instrumentation used for inputs to the DEFAS is diverse from the steam generator level instrumentation for inputs to the PPS.
The DEFAS relay logic is diverse from the EFAS. The DEFAS output relays operate the Emergency Feedwater System (EFS) equipment directly through the interface wiring with tLe EFS equipment control circuits.
See Figures 7 and 8, which illustrate the diversity from the existing RTS.
4.
Electrical Independence from Existing PPS See Section, 7, response to Question 1, and Figure 4.
NS100283E - - _ _ _ _ _ _ _ - - _ _ _ _ _ - _ _ _ _ _ _ _
A 5.
Design Compliance with NRC Guidelines for 10CFR50.62 (ATWS) Rule (Cont'd)
The power supplies are capable of performing L their'. required-design functions upon loss-of-site power.
5.
Quality Assurance. for Test, liaintenance, and ' Surveillance The. DRTS and DEFAS equipment will be-treated under a quality assurance program that. is consistent with the guidance contained in. Generic Le..ter 85-06.
Safety related interfaces - and other portions '. of the DRTS and DEFAS will be controlled in accordance with the approved 10CFR50, Appendix B Quality Assurance' Program.
- 6..
Safety Related (IE) Power Supply See Section 7, response.to Question 1.
7.
Inadvertent Actuation-The DRTS and DEFAS are designed with features' to minirnize inadvertent actuations and challenges to safety ' systems.
The-systems' will not interfere with the expected PPS response to design basis accidents.
The actuation of the. DRTS and DEFAS is designed to operate equipment upon energization of the initiating relays. This design is opposite of the PPS in that the PPS initiation relay actuates equipment on de-energization.
The cetpoio.ts for initiating the DRTS or DElAS are selected such that the in.'tiation of.the DRTS and DEFAS prior to PPS initiation is prever.tet. The design of the;DRTS and DEFAS incorporates C1ses IE isolaf. ion devices, single-failure criterion, 'and enhanced logic (e.g.
I-out-of-2 channels, steam generator pressure ' permissive),
to fmther assure that the inadvertent actuation of these systems -
is precluded.
8.
Testability at Power Test of Diverse Reactor Trip System (DRTS):
The test of the primary instrumentation loops and DRTS relay logic can be performed during plant operation.
The test circuitry and' the test methods are established such that inadvertent trip of reactor is prevented during the test. Refer to Section 2 of this report for the details of test performance.
NS100283E _ _ _ - _ _
5.
Design Compliance with NRC Guidelines for 10CFR50.62 (ATWS) Rule (Cont'd) 8.
Testability at Power (Cont'd)
Test of DEFAS:
The. test of DEFAS can be performed during plant operation.
The-DEFAS circuits consists of non-safety related relay logic used for. initiation of DEFAS and two safety channels SA and SB with operational relays. The test circuit and the test methods are established such that inadvertent feeding of the steam generator during the test period is ' precluded.
Refer to Section 3E of this raport for the details of performance.
The frequency of At-Power tests for DRTS and DEFAS can be the same as PPS testing.
The circuitry and methods are established to perform the end-to-end test each refueling outage..
Operational testing of the DRTS and DEFAS equipment will be completed prior to placing the system into initial service.
9.
Physical Separation form Existing RTS Physical separation of the DRTS and DEFAS from the existing Reactor Protection System (RPS) is not required because the redundant divisions and channels of the RPS meet Regulatory Guide 1.75 separation criteria as documented in FSAR Section 8.3.1.2.13.
However, for conservatism, the implementation of the Waterford-3 ATWS. mitigating systems are such that the separation criteria applied to the RPS are not violated.
The DRTS and DEFAS logic circuitry is located in cabinets which are physically 'eparated (different room) from the RPS logic cabinets.
Cable routings and electrical isolation are maintained in accordance with Reg. Guide 1.75 and IEEE-384-1974 as described in FSAR Sections 7.2, 7.3, and 8.3 Thus, the DRTS and DEFAS are protected from any postulated common-cause failure which may catastrophically destroy the RPS logic cabinets.
- 10. Environmental Qualification Consistent with the of 10CFR50.62 guid elines, the DRTS and DEFAS equipment will be designed and srlected to withstand its anticipated service environment The new DRTS and DEFAS cabinet eqtipment will be located in areas within the plant which arc.
v isidered a mild environment.
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5.
Design compliance with NRC Guidelines for 10CFR50.62.(ATWS) Rule
-(Cont'd)
I
~
The installation of the DRTS and DEFAS. will not degrade the l
existing qualification of safety related equipment:in the plant.
f The design of the DRTS and DEFAS will minimize the potential for 1
inadvertent actuation; thus, the installation of these systems will not increase the environmental paramete:s used in the equipment qualification prograia.
11.
Seismic Qualification l
An interlock is provided in the DEFAS control scheme to allow the automatic actuation of the DEFAS only if the DRTS is also actuated.
This interlock is designed to restrict the automatic initiation of the DEFAS to the condition in the plant that is indicative of an ATWS and at the same time to preclude the auto-matic initiation of DEFAS when the PPS is expected to function in i
accordance with its design with allowances for the single failure criteria.
Equipment in the safety portion of the DRTS and DEFAS is seis-mically qualified.
Non-safety components of the D.fTS and DEFAS are located in auxiliary relay panel 4 and loca. panels which are non-nuclear safety.
These panels are located such that the safety related interfaces are not degraded.
The non-safety control room com-ponents mounting will meet seismic requirements.
NS100283E _ _ - _ _ _
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6.
COMPONENTS & QUALIFICATIONS i
NS100283E
-e
.6.
Components & Qualifications-DRTS/DEFAS CLASS IE COMPONENTS i
ITEM SEE-NO.
DESCRIPTION TAG NO.
NFR MODEL NO.
NOTE 1
Actuation Relays DFVA Potter &
MDR-163-1 1
f DFVB Brumfield DFPA 5
DFPB 2'
Isolation Relays NSA Electro Type 24CSR 2
NSB Switch P1AB Corp.
P2BA 3
Test Switches TS-A Micro PTS 3
TS-B Switch 4
Isolator Cards NLP3 Westinghouse 2837A12G03 4, 5 5
Loop Power NLP2 Westinghouse 2837A12G02 4, 5 Supply Cards 6
Channel Test NCTI Westinghouse 2837A91G01 4
Cards 7
Contact Output NC01 Westinghouse 2839A42G01 4
Card 8
Analog Comparator NAC1 Westinghouse 2838A32G01 4
Card 9
Pressurizer PT-RC9120A ITT Barton 763 6
Pressure PT-RC9120B Transmitter NS100283E. _ _ - _ _ _ _ _ _ _ _ -
6.
Components & Qualifications (Cont'd) l DRTS/DEFAS NON-SAFETY COMPONENTS l
ITEM SEE NO.
DESCRIPTION TAG NO.
MFR MODEL NO.
NOTE 1
Selector Switches SS(DRTS)
Micro CMC 7
SS(DEFAS)
Switch 2
Push Buttons PB-A Micro PTP 7
PB-B Switch PB/ACT-A PB/ACT-B 3
Analog to Digital RPHA Rochester ET-1215 8
(A/D) Converters RPHB Instrument LIA Systems (RIS)
L2A LIB L2B 4
Auxiliary Relays YA Allen 700 Series 8
TB Bradley Type F DFA Industrial DFB Relay 5
Latching Relays TP Potter &
MDR-6064 8
DFP Brumfield MDR-4067 i
j j
NS100283E 4
6.
Components & Qualifications (Cont'd)
NOTES:
1.
Qualified to IEEE-323 and 344.
2.
Qualified to IEEE-323 and 344.
3.
Qualified to IEE-323 and 344.
4.
Qualification Report Westinghouse PAC Systems:
a)
" Equipment Qualification Test Report Process Protectica System Seismic Testing" dated July, 1981 prepared by Westinghouse Test Report No. WCAP 8687 Supplement 2 E13A b)
" Equipment Qualification Test Report Process Protection System -
Seismic Testing" dated July, 1980 prepared by Westinghouse Test Report No. WCAP 8687 Supplement 2 E13B 5.
Test Report for qualifying Isolator Cards as a Class 1E isolation device.
Test Report No. WCAP 8892A prepared by Westinghouse 6.
Qualification Report ITT Barton Pressure Transmitters:
" Class IE Qualification Test Program and Results for ITT Barton Gage Pressure Transmitter Model 763" dated September, 1982 prepared by ITT Barton Instruments Test Report No. R3-763-6 7.
Non-Class 1E ccmponents to be mounted on Main Control Room Panel (Seismic Category I) will be seismically qualified to prevent missile damage to its surroundings.
9.
Components are non-safety /non-seismic I
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NS100283E l l
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REVISED RESPONSES TO THE NRC DECEMBER 20, 1988 REQUEST FOR ADDITIONAL INFORMATION (RAI) i NS100283E
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7.
Revised Responses to the.NRC December 20, 1988 Request for Additional-Information- (RAI) l Below are ' the" response to the ~ December 20,- 1988 RAI considering the-revised. functional design of the DRTS (formerly _ DSS)'and also based on implementation of the proposed DEFAS.
- 1) Use of RPS Power Supplies K
Question / Concern:
One of the requirements of the ATWS Rule is that' the. ATWS prevention / mitigation system be electrically independent from the-existing RPS power supplies. The purpose of this ' requirement:is to -
prevent faults within non-safety related ATWS circuits from degrad-ing the safety-related RPS. Also, the required electrical indepen-dence will prevent those interactions between systems that would allow a common mode failure (CMF) to affect both the-RPS and DRTS equipment, since such interactions could potentially compromise the added diversity that the equipment installed toEprevent.un-acceptable plant ~ conditions upon failure of the RPS is intended to provide.
- Figure 1 of the 10/7/88 submittal indicates that the existing RTS:
Instrument power (AC vital bus) is used for the DRTS instrument bistable and bistable relays.
Please justify the use of the existing RTS instrument power for the DRTS instruments, and demonstrate that the possibility of common mode failure is prevented.
' Response:
The PPS ' cabinet and the associated sensor instrumentation loops, located in cabinets CP-25, CP-26, CP-27 and CP-28 are powered from four distinct power distribution panels (PDP) located in four pro-tective channels: SMA, SMB, SMC, and SMD.
The power distribution to the PPS equipment is as follows:
Channel PDP Cabinet SNA 3MA-S PPS, CP-25 SMB 3MB-S PPS, CP-26 SMC 3MC-S PPS, CP-27 SMD 3MD-S PPS, CP-28 The safety related sensor instrumentation loops of DRTS and DEFAS are located in cabinets LCP-61 and LCP-62.
The power distribution to the DRTS and DEFAS sensors is as follows:
Channel PDP Cabinet SA 3MA-S LCP-61 SB 3MB-S LCP-62 NS100283E -
'A 7.
Revl4ed Responses to the NRC December 20, 1988 Request for Additional
~
Information (RAI)
(Cont'd)
The non-safety related relay logics of DRTS and DEFAS are powered from PDP 396AB, which is independent or PPS. The PDP 396AB is fed from the SUPS-3AB which is supplied from the 3AB-S 125 VDC bat-tery.
The 3AB-S battery supply is not physically connected to the 3A-S and 3B-S batteries, which supply power to the PPS -(See Figure 4).
The power distribution to the isolation and actuation relays in the DEFAS safety related channels is independent of PPS and is as follows:
Channel PDP SA 390-SA SB 391-SB The loss of either PDP will disable the DEFAS only.
It is concluded that no common mode failure exist that could affect the PPS and DRTS/DEFAS simultaneously.
The ATWS prevention / mitigation system is electrically independent of the existing RPS power supplies. Faults within the non-safety related ATWS circuits will not degrade the safety related PPS.
There are no common mode failures that will affect both RPS and DRTS/DEFAS equipment.
Question / Concern:
Please clarify that the "125V DC vital bus" which supplies power to the RTS circuit breaker UV and shunt trip coils is not the same "125V - DC vital bus" which supplies power to the DRTS/DTT power relays.
Describe the association if any, between the RTS power and the 125V DC vital bus power used on the DRTS actuation relay.
Response
With the present design for the DRTS and DEFAS,125V DC buses are not used to power the systems.
NS100283E I
7.
Revised Responses to the NRC December 20, 1988 Request for Additional Information (RAI)
(Cont'd) 2.
Testability / Maintenance Provide a discussion which addresses:
Question / Concern:
a)
The proposed frequency (if any) of the AT-Power tests.
Response
Test of Diverse Reactor Trip System (DRTS):
the test of the primary instrumentation loops and DRTS relay logic can be performed during power operation. The test cir-cuitry and the test methods are established such that inadvertent trip of the reactor is prevented during the test. Refer to Section "2-E" of this report for the de-tails of test performance.
Test of DEFAS:
The test of DEFAS can be performed during plant operation.
The DEFAS circuits consist of.
non-safety related relay logic for initiation of DEFAS and two safety channels SA and SB with operational relays.
The test circuit and the test methods are established such that inadvertent feeding of a steam generator during the test period is precluded. Refer to Section "3E" of this report for the details of the test performance.
The frequency of AT-Power test a for DRTS and DEFAS is tentatively set to be consistent with RPS/ESFAS testing.
Question / Concern:
b)
The proposed plans for performing an overall End-to-End test each refueling outage.
Response
Test circuitry and methods are established to perform the End-to-End test each refueling outage.
See Section 3E.
Question / Concern:
c)
The plant procedures used for maintenance and testing which will ensure that the ATWS prevention / mitigation circuits will be returned to service.
NS100283E - - - - -. - - - - - - - _ -. _ _ _ _ _
1
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'g 7.
Revised Responses to the NRC December 20, 1988 Request for Additional Information (RAI)
(Cont'd)
I Responses:
While plant test procedures for the ATWS systems have not yet been developed, they will incorporate a requirement to return the systems to service following testing provided the systems are operable.
i i
3.
Means for Bypassing Question / Concern:
State the method (s) used to effect maintenance and/or test by-passes.
Indicate whether the bypasses involve undesirable
. practices such as installing jumpers, lifting leads, pulling fuses',
tripping breakers, blocking relays, or other circuits modifications.
Response
Selector switches and push buttons are provided to deactivate the system for maintenance and also to bypass portions of the circuitry during testing.
The design of test circuitry and controls is such that installation of jumpers, lifting leads, pulling-fuses, tripping breakers, blocking relays etc. are eliminated.
See Section 2E and 3E for further details.
4.
Equipment Qualification Question / Concern:
The Barton pressure transmitters appear to have been added to accommodate the DRTS.
a) Are the instruments qualified for use on the Class IE RTS power?
b) Are the instruments qualified for the zone in which they are installed?
Response
a) & b) l Refer to Section 6, " Components & Qualification" of this report.
l The Barton transmitters are qualified for Class IE use.
The transmitters were not added to accommodate the DRTS but rather to meet an outstanding commitment to provide 0-4000 psi indication under Regulatory Guide 1.97.
1 NS100283E )
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- Q 7.
Revised Responses to the.NRC December 20, 1988 Request for Additional Information (RA1)
(Cont'd)
I 5.
Completion of Mitigative Active l
Question / Concern:
Provide a discussion describing how the ATWS mitigative action goes to completion once it has started.
Response
Completion of mitigative action is described in applicable sections of the report.
6.
Manual Initiation Question / Concern:
l l
Describe the manual initiation capability of the ATWS mitigation function.
Response
i DRTS: Two push buttons are provided on the main control board for manual initiation of the DRTS.
Depressing both push buttons i
simultaneously will result in the reactor trip.
See Section 2A for additional information.
DEFAS: Two push buttons are provided on the main control board to provide the means of manual initiation of DEFAS. Depressing both push buttons simultaneously will result' in operation of the initiating relays of the DEFAS and transfer of the DEFAS initiation signals to the DEFAS actuation relays in safety channels SA and SB.
They will also start the EFW system equipment to feed the steam generators.
See Section 3A for additional information.
7.
Block Diagrams Question / Concern:
1.
Provide control diagrams showing the DRTS interface with the control rod power circuit.
The diagram should show specifically how the DRTS interrupts the control rod power.
I I
Response
Refer to Figures 1, 2, 4, 5, 6, and 7.
l 1
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~7.
Revised Responses to the NRC December 20, 1988 Request for Additional-Information (RAI)
(Cont'd) 8.
. Isolation Devices.
Question / Concern:
The adeq'uacy of all. isolation devices.used to protect the integrity of safety-related ' circuits from the non-safety related ATWS' DRTS.
and DTT circuits must be demonstrated. The information required is ll identified in Attachment 1 and the following:
l l~
a). Identify the newly created safety /non-safety related interfaces-which are a. result of the implementation of the ATWS Rule requirements.
b) Identify the' isolation device (s) proposed for use in protecting the safety circuit interfaces listed in. item (a) above.
c)
Provide data showing that the isolation devices identified in-
. item (b) above have been tested by application of the maximum credible faul. (MCF) voltage / current in the transverse mode to its non-safety side (See Attachment' 1).
Also show that the isolation devices in this new ~ application are bounded by the MCF tests.
Response
a), b) & c)
See Section-6 for a listing of the DRTS/DTT safety /non-safety isolation devices, and Figures 2 and 3 for interfaces.
.We did not introduce any new. type of isolation device into the DRTS and. DEFAS control logic and power.
The type.of isolation -
components that are used for DRTS and DEFAS are the same as those qualified for obtaining the Waterford 3 operating license.
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- 8. FIGURES Diverse Reactor Trip System Control and Annunciation Figure 1 Figure 2 Diverse Reactor Trip Schematic Sheet 1 of 2 - Diverse EFW System (DEFAS) Schematic Figure 3 Sheet 2 of 2 - Diverse EFW System (DEFAS) Schematic Figure 3 Figure 4 ATWS Power Supply. Interface Diverse Reactor Trip System (DRTS) If-G Set Output Figure 5 Contactor Control Interface Figure 6 ATWS Protection Systems Figure 7 Diversity Between the Existing Reactor Trip System and the Diverse Reactor Trip System / Diverse Turbine Trip Figure 8 Diversity Between the Existing EFW System and the Diverse EFW System l
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