ML20133K475
| ML20133K475 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/15/1985 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-5-141, TAC-62915, NUDOCS 8510220030 | |
| Download: ML20133K475 (37) | |
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~Ii 12 7s7 st Nuclear Construction Dmsson Telecopy 2
2 IttEn. p*l'is2Os "
October 15, 1985 8"
United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Mr. George W. Knighton, Chief Licensing Branch 3 Office of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Final Draf t Safety Evaluation Report Confinnatory Issue 34 Gentlemen:
In letter 2NRC-4-119 of August 9,
1984, Duquesne Light Company indicated that a detailed plant review would be conducted to assure that a control system failure would not result in an event which was more severe than the design basis events analyzed in the FSAR.
The analysis is conplete and the results are attached to this letter.
This infonnation conpletes the Duquesne Light Company action for Confirmatory Issue 34, which should close this Final Draft SER issue.
DUQUESNE LIGHT COMPANY 1*1 By J. J. Carey Vice President KAT/wjs Attachment cc:
Mr. B. K. Singh, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a) 8510220030 851015 s
PDR ADOCK 05000412 E
PDR lt
ANALYSIS OF CONTROL SYSTEM FAILURES l
r CONTROL SYSTEM FAILURE CONCERNS i
The analyses reported in Chapter 15 of the FSAR are intended to demonstrate l
the adequacy of safety systems in mitigating anticipated operational occurrences and eccidents.
l 1
Based on the conservative assumptions made in defining these design-basis evants and the detailed review of the analysis by the staff, it is likely that-l l
they adequately bound the consequences of' single control system failures.
f To provide assurance that the design basis event analyses adequately bound other more fundamental credible failures, you are requested to provide.the following information:
l (1) Identify those control systems whose failure or malfunction coeld seriously impact plant safety.
i (2) Indicate which, if any, of the control systems identified in (1) receive
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power from cowren power sources. The power sources considered should include all power sources whose failure or malfunction ~could lead to failure or malfunction of more than one control system and should extend t
to the effects of cascading power losses due to the failure of higher level distribution panels and load centers.
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(3) Indicate which, if any, of the control systems identified in (1) receive input signals from common sensors. The sensors considered should include, l
but'should not necessarily be limited to, common hydraulic headers or I
impulse lines feeding pressure, temperature, level or other signals to two or more control systems.
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2605e:1d/022285 1
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(4) Provide justification that any simultaneous malfunctions of the control systems identified in (2) and (3) resulting from failures or malfunctions of the applicable common power source or sensor are bounded by the analyses in Chapter 15 and would not require action or response beyond the capability of operators or safety systems.
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RESPONSE TO DMW FSAR QUESTION 420.6 ON CONTROL SYSTEM FAILURE INTRODUCTION The evaluation consists of postulating failures which affect the major NSSS control systems and demonstration that for each failure the resulting event is within the bounds of existing accident analyses. The events which are considered are:
a) Loss of any single instrument b) Break of any single common instrument line c) Loss of power to all systems powered by a single power supply system (i.e.
single inverter) d) Loss of power to individual protection, control, or NIS rack The analysis is conducted for all five major NSSS control systems:
- 1) Reactor control system
- 2) Steam dump system
- 3) Pressurizer pressure control system
- 4) Pressurizer level control system
- 5) Feedwater control system The initial conditions for the analysis are assumed to be anywhere within the full operating power range of the plant (i.e. 0-100%) where applicable.
The results of the analysis indicate that, for any of the postulated events considered in a) through d) above, the condition II accident analyses given in Chapter 15 of the Beaver Valley Unit II FSAR are bounding.
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a LOSS OF ANY SINGLE INSTRUMENT Table 1, Loss of Any Single Instrument, is a sensor-by-sensor evaluation of the effect on the control systems itemized above caused by a sensor failing either high or low. The particular sensor considered is given, along with the number of channels which exist, the failed channel, the control systems impacted by the sensor, the effects on the control systems for failures in both directions, and the bounding FSAR accident. Where no control action occurs or where control action is in a safe direction, no bounding accident is given.
The table clearly shows that for any single instrument failure, either high or low, the condition II events itemized in the FSAR Chapter 15 are bounding.
LOSS OF POWER The Beavery Valley Unit II power supplies related to this question. consist of four vital power busses powered by their own inverters. The protection system is divided into four prctection sets, the control system into four control groups, and the nuclear instrumentation system into four NIS racks.
Each of these is powered hy the corresponding inverter vital bus, i.e. Inverter Vital Power Bus I supplies power to Protection Set I, Control Group 1 and NIS Rack I, and similarly for the other three busses.
Tables 2 through 5, Loss of Power to Inverters I through IV respectively, analyze the effects on the control systems caused hy the most limiting failure, loss of power to an entire inverter vital bus. The control systems affected, the sensors affected, the failure direction, the control responses, and the bounding FSAR accident are given in the tables. Where no control action occurs or where control action is in a safe direction, no bounding accident is given.
Besides the loss of an inverter, there is also a chance of losing power to a single control group, protection set, or NIS rack (for example, through the failure of a fuse or circuit breaker). The consequences of a loss of power to 2605e:1d/031585 4
a a control group are tabulated in Tables 6 through 9.
Loss of power to a protection set is addressed in Tables 10 through 13. Finally, Tables 14 through 17 consider loss of power to the NIS racks.
In each case, the data is presented 'in a similar manner to that for the loss of an inverter described in.
the previous paragraph.
Besides the loss of power to an entire control group, there is the chance of having an electrical fault on one of the control system circuit cards.
The control systems are designed so that each card is used in only one control system.
A circuit card failure cannot directly impact more than one control system. A failure on a control card would cause the controller to generate either an "off" or a " full on" output, depending on the type of failure.
This result would be similar to having a fault in a sensor feeding the control system. Therefore, the failure of or loss of power in any control system circuit card would be bounded by the Loss of Any Single Instrument analysis described in Table 1.
The tables show that for a loss of power to any inverter, protection cabinet, control cabinet, or NIS rack, the Condition II events analyzed in the FSAR Chapter 15 are bounding.
LOSS OF COMMON INSTRLMENT LINES Table 18, Loss of Comon Instrument Lines, considers the scenario whereby an instrument line which supplies more than one signal ruptures, causing faulty sensor readings.
l Two sets of sensors are located in common lines:
l l
- 1) Loop steam flow (Protection Set III for each steam generator) and narrow l
range steam generator level (Protection Set III for each steam generator).
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- 2) Pressurizer level (Protection Set III) and pressurizer pressure (Control Groups III or IV).
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l Table 18 shows that in the event of a common instrument ifne break, the Condition II events itemized in the FSAR Chapter 15 are bounding.
Not shown on the table since they are not part of the plant control system but are used just for protection are the RCS loop flow transmitters. There are three flow transmitters in each loop, with each transmitter having a comon high pressure tap but separate and unique low pressure taps. Therefore, a break at the high pressure flow transmitter tap would result in disabling all three flow transmitters in one loop, resulting in a low flow reading for all three transmitters. This would result in a reactor trip if the plant is above the P-8 setpoint, or an annunciation if it is below P-8.
The only malfunction mode explicitly analyzed was a break in the common instrument line at the tap. Another possibility is to have a complete blockage in the sensor tap, causing the sensor to read a constant (before blockage) value. However, this last failure mode is not analyzed since it is really not a credible event. There is no anticipated agent available that would cause a tap blockage. The Reactor Coolant System piping and fittings, and the instrument impulse line tubing are all stainless steel, so no products of corrosion are expected. Also the water chemistry is of high quality, which along with high temperature operation, precludes the presence of solids in the water and assures the maintenance of the solubility of chemicals in the water.
In addition, prior to startup, and during any shutdown as well, it is l
routine maintenance and servicing practice for. instrument lines to be blown down to a canister.
Since the building of sludge is a slow process, any i
buildup would be detected during response time testing done during shutdown.
therefore, the hypothesis of the presence of a complete blockage of the sensor tap is not sufficiently credible to warrant its consideration as a design basis.
In the extremely unlikely event that a complete instrument line blockage were l
to occur, the condition is detectable because the reading would become static j
(no variation: over time).
In an unblocked channel, a reading would always vary somewhat due to noise (i.e. flow induced noise in flow channels) or slight controller action (i.e. cycling operation of spray and heaters in l
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i pressurizer). By a comparison of the static channel to the redundant unblocked channels, the operator would be informed that a blockage in one t
channel has occurred.
r CONCLUSIONS J
The attached tables have illustrated that failures of individual sensors,
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losses of power to inverters, losses of power to individual protection, I
control, and auxiliary process cabinets, or breaks in common instrument lines j
all result in events which are bounded by FSAR Chapter 15 analyses.
Therefore, the FSAR adequately bounds the consequences of-these fundamental failures.
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LIST OF TABLES Table 1 -
Loss of Any Single Instrument Table 2 -
Loss of Power to Inverter Vital Bus I Table 3 -
Loss of Power to Inverter Vital Bus II Table 4 -
Loss of Power to Inverter Vital Bus III Table 5 -
Loss of Power to Inverter Vital Bus IV Table 6 -
Loss of Power to Control Group I Table 7 -
Loss of Power to Control Group II Table 8 -
Loss of Power to Control Group III i
Table 9 -
Loss of Power to Control Group IV Table 10 - Loss of Power to Protection Set I Table 11 - Loss of Power to Protection Set II Table 12 - Loss of Power to Protection Set III Table 13 - Loss of Power to Protection Set IV Table.14 - Loss of Power to h!S I Table 15 - Loss of Power to WIS II Table 16 - Loss of Power to NIS III j
Table 17 - Loss of Power to NIS IV Table 18 - Loss of Common Instrument Lines 9
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'TAett 1 LOSS OF ANY SINGtt INSTRUMENT NUM9tR ASSUMt B 0F FAllt0 FAltutt BOUNOING steI50R CHANNELS
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$1}JI{!!
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_ [ VENT 5ttam I per o s'eam Dump to Dump Valves Close.
Bounding twent is Loss Headir plant
(=ressure Mode (5.G. PDRV's available of External Lead Prtsstre Only)
If needed.)
(F5AR 15.2.2) (if trip occurs) or no event.
Hi Dump valves open.
Steam dump in pressure (Steam dump blocked on mode at hot standby d
to-lo IAVG (P-12).)
or very low power only.
Hence, dump valves will open for only a very short tlne till 1
10-10 TAVG (P-12) is reached. This event is bounded by Excessive Increase in Secondary Steam flow l
(F5AR 15.1.3).
l Loop 2 per I selected a feedwater to fW valves close if in auto If FCV in manual -
Stram loop for control Control mode.
no event. If FCV in tiow auto results in j
decreased FW flow, I
bounding event is Loss of Norwel FW Flow (75AR 15.2.7) 2558e:Id/022005 1
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e TABLE i (Continued)
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LOSS OF ANY 5tNGtt IN51RUMENT NUMeta A$509f D OF F AltID FAILU#E BOUNOING SENSDR CHANNtl$
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(V[Ni HI FW valves open if in auto if FCV in manual - no mode.
event. If FCV in auto results in increased FW flow, bounding event is Excessive FW Flow (FSAR 15.1.2)
Loop FW 2 per I selected o feedwater to FW valve opens if in auto mode if FCV is manual - no flow loop for control Control event. If FCV in auto results in increased FW flow, bounding event is Excessive FW Flow (FSAR 15.1.2)
HI FW valve closes if in auto mode If FCV in nenual - no-event. If FCV is auto, result is decreased FW flow, bounding event is Loss of Nornet FW Flow (FSAR 15.2.7)
Narrow 3 per Steam I used o Feedwater le FW valve opens if in auto mode If FCV in manual - no R:nge Generator for control Cont rol event. If FCV in auto tevel (one available (111) results in increased for control)
FW flow, bounding event is Excessive FW Flow (FSAR 15.1.2) 2558e:Id/022005 2
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TA9tE 1 (Continued)
LOSS OF ANY $1NGLE IN$1RtN4(NT Hl IW valve closes if in If FCV in manual - no auto mode, event. If FCV 15 auto, result is decreased FW flow, bounding e* vent is Loss of Normal fW Flow (FSAR 15.2.7)
Pressurtrer 3 per I (pos 2 or 3) o Prr, tevel to Charging flow increases.
Bounding event is tswel plant III (pos 1)*
Control Heaters turn off (except for increased Reactor (Control) local control).
Coolant inventory Letdown Isolated (VCT empties, (FSAR 15.5.2) charging pumps take suction-from RWST.)
HI Charging flow decreases While heaters are on, Backup heaters on (Later, let-no net depressurtration down isolation f rom Interlock of RCS. After heaters channel, heaters blocked are blocked, decreased from interlock channel.)
charging flow acts to depressurtre RCS.
Depressurization event is therefore bounded by inadvertent Opening of a Pressottrer Safety or Relief Valve (fSAR 15.6.1) 2558e:1d/022085 3
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e TABLE 1 (Continnd)
LOSS Of ANY SINGtt INSTRUNf Mi Pressur1rer 3 per II (pos I or 2) o Prr, tevel to tetdown isolated. Prr. heaters Steady-state reached Level plant til (pos 3)*
Control blocked (ercept for total at slightly high (Interloc k )
control).(Charging flow reduced level. No event.
to maintain level).
l H1 No control attlen, get Hl level annunciation.
Not app 11 cable Pressurtrer 2 per Ill o Pir. Pressure to
.No control attlen.
Not applicable Pressure plant-Control PORV 456 and PORV 4550 blocked (for control) from opening. PORV 455C available if required, closes when pressure falls below deadhand.
j Hi PORV 456 abd 4550 open Result is bounded by inadvertent Opening of J
l a F7r. Safety or Relief Vaive (tsar 15.6.1)
Pressurizer 2 per IV o Pir. Pressure to PORY 455C blocked. Heaters Heaters being on causes Pressure plant Control turn on, spray remains off.
Increase in Pir pres-(for control)
Sure to PORY 456 and PORY 4550 actuation, j
No event.
i M1 PORY 455C opens.
Result is bounded by Spray turned on.
Inadvertent opening of a Prr. Safety or Relief f
Valve (f5AR 15.6.1)
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IABLC 1 (Continued)
LOSS OF ANY SINGlt INSTRUNtNI TAVG one per Any
'O Steam Dung to No Control Action Not applicable loop (TAVG Mode)
Auct.
o Reactor Control HI o Prr Level Control HI Rods In (safe direction).
No event unless Charging flow increases until reactor trips, then full power Prr. level is reached dump valves open (if at reduced power). If reat-and bo:inding event is ter trips, steam cump enabled Excessive Increase in and dump valves open untti Secondary Steam Flow steam dung blocked when to-lo (FSAR 15.1.3) 1 AVG 15 reached (P12),
T Ayr, one per Any
'-o Steam Dung to No Control Action Not applicable
.I loop (Pressure Mode)
Auct.
o Reactor Control HI
_o Prr Level Control HI Rods in (Safe direction).
Steady state reached Charging flow increases until at full power pres-full power Prr level is surtrer level.
reached (if at reduced power).
No event.
Turbine 2 per til o Steam Dump to Rods in (safe direction) auto Bounded by toss lopulse turtine (Control)
(TAVG Mode) rod withdrawal blocked of Normal FW flow Chamber
~o Reactor Control (C-5).
Steam dump signaled to (f5AR 15.2.1) if 4
Pressure Selected o FW Control open but is blocked by interlock, reactor trips, or 3
(if reactor trip occurs, steam no event.
steam dump unblocked and dump valves modulate untti no load TAVG is reached).
TW Control System controls to lower (No load) setpoint.
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TABtt 1 (Continued) 1055 0F ANY'51NGli INSIRUMENI HI Rods out until blo'.ked by Result is bounded by HI flux, overpower, or over-Uncontrolled Rod temperature, rod stop, or Cluster Control until progransned 1REF limit Assembly Bank With-is reached. (If reactor trip drawal at Power occurs, steam dump unblocked (F$AR 15.4.2) and dump valves open untti no load 1 AVG is reached. FW Control System controls to nominal Full power setpoint.
Ttrbine 2 per III o Steam Dump to Rods in, (ssfe direction) auto Bounded by toss of Impulse turbine (Control)
(Pressure Mode) rod withdrawal blocked (C-5),
Normal SW flow (F$AR Chamber
- o Reactor Control FW Control System controls to 15.2.7)
Fressure Selected'~
o FW Control lower (No load) setpoint.
HI Rods out until blocked by Result is bounded by H1 flux, overpower, or over-Uncontrolled Rod temperature rod stop. (Steam Cluster Control i
dump valves open if required Assembly Bank With-to keep steam header pressure drawal at Power at or below setpoint).
(FSAR 15.4.2).
fW Control System Controls to nominal Full Power Setpoint.
Ttrbine 2 per III o Steam Dump to Steam dump signated to open but Not Applicable.
Impulse turbine (Control)
(TAVG Mode) is blocked by interlock. (if Chamber (Reactor Control reactor trip occurs, steam dump Pressure and IW Control unblocked and dump valves modu-not Selected) late until no load TAVG 15 reached).
2559e:1d/031585 6
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TA8tE 1 (Continued) 1055 0F ANY SINGtt IN51RCitNI Hi No control actlon (if reatter Not Applicable.
trip occurs, steam dump unblocked and dump valves open until no Ioad I,,g h reac W.
TErbine' 2 per til o Steam Dump to Steam dug functions normally.
Not Appilcable.
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Impulse turbine (Contrci)
(pressure mode) or Chamber (Reactor Control Hi Pressure and IW Control not selected).
Terbine 2 per ly o Steam Dump to Rods in (safe direction), auto Bounded by loss Impulse turbine (Interlock)
(TAVG Mode) rod withdrawal blocked (C-5).
of Norinal FW Flow Chamber
' o Reactor Control Steam dusp unblocked (If reactor (f5AR 15.2.7)
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Pressure Selected ~ _ o FW Control trips Steam Dug system functions normally). FW Control System controls to lower (No load) setroint.
Mi Rods out until blocked by HI Result 15 bounded by flur, overpower, or over-Uncontrolled Rod temperature., rod stop, or Cluster Control untti prograssmed TRtf Ilmit Assembly Bank With-15 reached. (If reactor trip drawal at Power 4
occurs, steam dump functions (f5AR 15.4.2) normally), FW Control System controls to nominal Full power setrotnt.
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LOSS OF ANY SINGtt INSTRtMNI Turbine t per IV o Steam Dump to Rods in (safe direction), auto Bounded by loss Ippelse turbine (Int erlock )
(Pressure Mode) red withdrawal blocked (C-5).
of Normel IW flow Chanter
' o Reactor Control Steam dump urblocked (if reactor (f544 15.2.7)"
Pressure Selected~
o IW Control trip occurs, steam dump func-tions normally), fW Control System controis to lower (No load) setpoint.
Mi Rods out until blocked by HI Result is bounded by flux, overpower, or over-Uncontrolled Rod temperature, rod stop, or Cluster Control untti programmed 1Rtf limit Asse*41y Bank With-ts reached. (if reactor trip drawal at Power occurs, steam dump functions (75AR 15.4.2).
normally). fW Control System contrels to nominal f ull power setpoint.
Turbine 2 per IV e Steam Dump to Unblock steam dump Not appilcable lupulse Turbine (Interlock)
(IAVG Mode)
Chamber (Reactor Control Pressure and fW Control not selected).
M1 Steam dung on turbine trip Not appilcable only, steam dump blocked on lead rejection.
255ee:1d/031585 8
.. -. ~. -. ~.
l 1AttE I (Continued)
LOSS OF ANY SINGtt INSIRUNtNT Turbine 2 per IV o Steam Dump to or Hl Steam dung functions normally.
Not appilcable Impulse Turblee (Interlock)
(Pressure Mode)
Chamber (Reactor Control Pressure and FW Control not selected).
Power Range I per o Reactor Control to Control rods withdraw (Power Result is bounded Fist plant o fW Control Sr. creases) until blocked by by Uncontrolled Rod (for Control) high flor, overtemperature or Cluster Control g
overpower rod stop. fW bypass Assembly Bank valve closes if in auto. Sub-Withdrawal at Power sequent $G 1evel deviation (f5AR 15.4.2) causes valve to reopen untti nominal level is restored.
M1 Auto and manual rod withdrawal Minor $6 level blocked (C-2), rods in (In perturbation safe direction). If reactor No event.
trip occurs, dump valves open until no-load TAVG 15 reached). FW bypass valve opens if in auto. Subsequent level deviation causes valve to close until nominal SG 1evel is restored.
Steamilne 1 per any o Steam dump to Steamilne atmospheric relief No event.
. Pressure Steamilne valve unavailable
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TA8tt 1 (ContInved).
LOS$ Of ANT SINGLE IN51RUMNT 1
i Hi Steamilne atmospheric relief Bounded by encessive i
valve opens increase in secondary steam flow (FSAR 15.1.3)
Condenser 1 per o Steam Duny to No control action-steam dump Mot applicable
)
Ayallable plant blocked, condenser unavallable.
Hj No control action-steam dump Not appilcable I
unblocked, condenser available.
TAVG I per o 5 team Dump to Steam dump blocked (TAVG mode).
Result is bounded by Illgh plant o Reactor Control Charging flow decreased untti Uncontrolled Rod i
Auc tioneer o
Pir. Level Control no-load level reached. Backup Cluster Control heaters on. Rods out, power Assembly Bank With-Increases until blocked by drawal at Power l
high flur. overpower, or (FSAR 15.4.2) overtemperature rod stop.
i Hi Indentical to IAVG channel See above j
falling high, see analysis above.
}
Steam Flow 2 per loop Control o
~5 team Flow to Identical to toop Steam flow See above Pressure Channel channel falling low. See Concensator analysts above.
Hl Identical to toop Steam flow See above channel falling high. See analysis above.
- signals f or pressurtrer level control and interinck car be obtained from dif ferent channels. Channel selection is achieved by manual 3 position switch in the control room. Resntting accident due to f ailed Instrument is dependent on switch position. Remaining combinations of switch positten and thannel fallure are non-events since failed channel is not selected for control.
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TABLE 2 LOSS OF POWER 10 INVIRitR VITAL Bus I (LO$$ DF POWER 10 PROTEtit0N SET I, CONIRDt GROUP I AND Ml$ RACK I)
CONTRot SYST EMS SIGNALS fAltuRE ITEMllED BOUNDING AFFECTED AFfLC1(O DIRECT 10#
EFFECIS (VENT Steam Dump o Steam 11ne atmospheric Off Steamilne atmospheric relief valves relief valves not available, no control action (system deenergized) r Reactor Control o None fW Control o None Bounding event is either increased Reactor Coolant Inventory (FSAR 15.5.2) or no event.
Pressuriter o Prr. Level (If selected)
Lo If af fected level signal used for control, tsvel charging flow increases, letdown isolated, heaters blocked. Otherwise, no control o Interlock (Bistable LB 460) to action.
Pressurtrer o Kone Pressure 2558e:1d/031585 11 r,
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TABLE 3 LOSS OF POWER TO l#vt'RIER VIIAL BUS II (LOSS OF POWER 10 P90ftCIION Sti II CONIROL GROUP 11 AND NIS RACK 11)
CONin0t SYSitNS SIGNALS IAILURE ITEMilED 800NOING AFFEC1(0 AFFECTED DIRECil04 ElFECIS_
EVENT 4
Steam Dump o turbine Pressure to Steam dump blocked. Steam Dump Bounding event is Loss of Normal
~ (Interlocks C-7A, C-78) unavailable 4 TW Flow (FSAR 15.2.7).
o C-g (condenser available) to Increased charging flow has little ef f ect in cogarison.
R7 actor Control o None t
i iW Control o All (system deenergtred) off Fw valve closes.
Loss of Main IW in SGI (Plant trips 4
I-(56 I) on low level in 56 1)
Pressurfrer o Par. Level to Charging FCV falls full open.
Charging Flow Increases. If Level Level o inarging Flow Control off signal 15 selected for interlock, letdown is isolated.
i Pressurizer o Mone Pressure i
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TABLE 4 LOSS OF POWER 10 INVIRIER WITAL BUS Ill (t055 0F POWER TO PRottCilDN SET III, CONTROL GRDUP !!! AND NIS RACK lil)
CDFTROL SYSTEMS SIGNALS Salt 0RE litMilt0 800NDING AFFEtito AFFECTED Q1RttilDN EFFECTS LVLN[___
Stiam Dump o Turbine impults chamber to to control action due to C-7 pressure (T,(,)
Interlock.
Rrsctor Control o turbine Impulse Chamber to Rods Inserted (Safe Bounding event is Loss of Normal Pressure (if selected) direction)
Inc reased Charging flow has little effect in comparison FW Control o SG2-A11 ($ystem IW Valve Loss of main FW in 56.2.
Plant Decnergi.ed Closes trips on Low level in SG-2.
Increase decrease or no change in fW flow to o Turbine Impulse Chamber to
$G1 and $63, depending on actual Pressure (if selected) channels selected for control.
o Steam Flow (lf selected) to o Feedwater Flow (if to selected) o SG 1evel to Pressuriger o Prr, Level to If affected level signal used for Level (Control or Interlock) control, charging flow increases, letdown isolated, heaters blocked.
If used for Interlock, heaters blocked and letdown isolated.
Otherwise, channel not connected, no control action.
2558e:Id/031585 13
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TA9tt 4 ('Contlaced)
LOSS of POWER 10 INVERTER VliAt 9U5 Ill (EDSS Of POWER TO P901ECTION SET lit. CONIROL GROUP Ill ANO NIS RACK lll)
CONTROL SYSTEMS SIGNALS FAltuRE ITEMilED 900NelNG AffECTED Af f ECTED 91RECil04 EFFECTS EVENT Pru s.rtrer o Par. Pressure to PORY 456 and PORY 4550 stay Presstre (PORV 456 and PORV closed. (PORV 455C available).
4550 Controi) 2558e:Td/022085 14 I
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T A8t'E 5 LOS$ OF POWER 10 INVERIER VilAt 905 IV (LOSS OF POWER TO PR0ftCil04 Sti IV, CONIROL GROUP IV AND MIS RACK IV) 00Nitet
$YSitNS SIGNAts fAlltiRE lifNiit0 BOUNOING AFittitO AFFitit0 ElRttil0N EFFECTS (VENf Stram Dune o All (System Deenergized)
Off/ Closed No initiating event, steam dump tucept Condenser system unavailable. (When reactor Avallable trip occurs, steamilne atmos, rellef va hes available).
ReIctsr Control o All (System Deenergized)
Off Rods stay stationary.
I IW Control o 543 - All ($ystem TW Valve toss of main fW in $G3, (Plant
(
Deenergized Closes trips on low level in SG3).
o Steam flow (if selected) to increase or decrease or no change o f eedwater flow (if to in fW flow to other $G's depending selected) on actual channels selected for o Power Range Fluu to control. FW bypass valves close o Turbine impulse Chaeber to if in auto.
Pressure (if selectei) f Presssrtrer o All (System Deenergtred)
Off Charging flow increases, backup Bounding event is toss of Normal tevel except LS 460 heater off, f W flow (FSAR 15.2.T).
Increased charging flow and pressurizer Presstrirer o Par. Pressure to PORY 456 stays closed.
transients have little effect l
Pressere (Control)
(Pressure increases altigated by in comparison.
(PORY 455C, spray and PORV 456 & PORY 4550). Variable Heater Control) and backup heaters remain off.
Pressure decreases alarmed by P84459).
l l
l 2558e:1d/022005 15 l
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140tt 6 LOSS OF POWER 10 CONTROL GROUP 1 C0881#0L SYSitMS SIGIIALS IAILUaE litMIZED 90tm0lMG Af f ECl[9 AFF ttitt DIRECit0_N
[FFEC15 LytNT Stram Dune o Steamilne atmospheric Off/ Closed No initiating event, steamilne relief valves atmospheric relief valves unavailable.
Rractse Control o None No signals affected, no No event.
control action FW Control o None No slgnals affected, no control action.
Press rtrer o Presseriter off No control attion.
Level tevel (tB a60)
Fresstrirer o None No signals af fected, no control Pressere action.
9 2550e:Id/022095 16 0
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l LOS$ Of POWER TO CONTROL GROUP 2 1
CONTRot
$YSILMS
$1 gnats f Alttml IltMill0 80V#0 LNG aFFECit9 AFFttitD OIRECTION QF,g_il,,
(VLNL Steam D e o
C-TA. C-79 interlocks off Steam dump blotted. Steam o C-g Interlocks Off dump weavailable.
Recctor Control o wone No signals affected, no control action, fW Control o All (System IW Valves Close toss of main FW in $.G.I.
Bounding event is toss of j
(5.6.1)
Deenergtred)
(Plant trips on low level Normal fW Flow (f5AR 15.2.1) l
-in 5.G.I.)
(Plant trips on low level i
in 5.G.I.)
lacreased charging i
flow has little effect in comparison.
Pressgrizer o Charging flow Control Off Changleg FCV falls open trvel Charging flow increases.
Posssgrtrer o None No control action.
Pressere I
2558e:Id/072005 11 6
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r TAett 8 LOSS Of POWER TO CONTR0l. GROUP 3.
CONTROL SYSTEMS SIGNALS 5AllUtt tilNilED BotNf0 LNG -
AFFECit8 AFFECT (O DIRECTION EFFECTS EvtNT Stram Dump o None No signals afIetted, no control action.
Reitter Control o None leo signals af fected, no control action.
FW Control o All (System FW Valve Closes toss of mein FW in S.G.2.
Bounding event is Loss of (S.G.2)
Deenergized)
(Plant trips on low level Normal fW Flow (FSAR 15.2.7) in S.G.2.)
(Plant trips on low level in S.G.2.)
Pressgrlter o None No signals affected, Ltytt no control action.
Pressgriter o PORT 456 and PORV 4550 to PORV 456 and FORV 4550 Press:re
- control, remain closed (PORV 455C avallatIleifneeded).
'!558e:Id/022065
' 18 g
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if8tt g LOSS OF POWER TO C04 TROL GROUP 4 CONTROL Sf51tNS SIGNALS TAltURE 111N1110 BOUNDING AFFECit0 AFittitD DIRECIIDW EFFttis LVtWT Stram Dump o All (except control to No Initiating event. Steam dump system permissive) (System unavailable. (If reactor trip occurs.
Deenergized) steamilne atmos. relief valves available.)
Ructsr Control o All (System Off Rods stay stationary Deenergized)
Bounding event is Loss of Normal FW Control o All (system FW Valve Closes Loss of main FW in 5.G.3. (Plant FW Flow (f5AR 15.2.7) since (5.G.3)
Deenerglred trips on low level in 5.G.3.)
increased charging flow has 1
Ilttle ef fect in comparison.
PrTssurtrer
'o All (escept LB460) to Charging flow increases. letdown (Plant trips on low 5.G.3 Level (System Deenergtred)
Isolated.
level.)
Pr2ss:rtrer o PORV 455C. spray and Off Normel Pressure control Pressrre heater control (System deactivated except for PORV 4554.
Deenergtred) 2558e:Id/022005 Ig i
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o IA8tt 12 LOSS Of POWER 10 PR0fttil04 Sti III CONTROL SY5itNS
$1GNALS fAltURE liENIlt0 BOUN0lWG AFFECit0 AFFEtitD qititil0N EFFttiS EVENT Steam Dump o Turbine impulse to No control action due to C-I interlock.
Chamber Pressure-(Control) tractor Control o Turbine impulse Chaaber to If selected. Rods Inserted (Safe Pressure (if selected)
Direction). Auto Rod withdrawal Bounding Event is either Excessive o C-5 Interlock to bloc k ed. Otherwise no control action.
FW Flow (f 5AR 15.1.2).
(Changing flow transtent is minor in comparison) loss of normal FW Flow (FSAR 15.2.1).
fW Control o 56 level to increase, decrease or no change (Charging Flow transient is minor o Steam Flow (if selected) to in FW Flow to loops, depending on in comparison), increased reactor o Feedwater Flow (if to
. actual channels selected for control.
coolant inventory (FSAR 15.5.2) o-selected) no events depending on actual o Turbine impulse Chamber to channels selected for control.
Pressurlier (if selected)
Pressur1rer o Pressurtzer level to if affected level signal used for Level control, charging flow facreases.
letdown isolated, heaters blocked.
If used for Interlock, heaters blocked and letdown Isolated. Otherwise, channel not cont.ected, no control action.
Pressurlier o None Pressure 4
2550e:Id/031585 22
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TA8tt 13 LOSS OF POWER 10 PR01EC110N SET IV CON 1ROL SYSTEMS StGNAls FAltuRE IIENillo BOUNDING AFFECTED AFFECTED ElRLCil0N LFFLC15 LVENT Steam Dump o Turbine Impulse Chamber to Steam Dump Unblocked Pressure (iriterlock)
R actor Control o turbine Ippulse Chamber to Rods Inserted (safe direction). Auto Pressure (if selected)
Rod Withdrawal Blocked.
fW Control o Stram Flow (if selected) to Feedwater flow can either increase, Bounding event is either facessive a
o feed Flow (if selected) to decrease or remain constant dependlntJ Feedwater flow (FSAR 15.1.2), no o Turbine Impulse Chamber on channels selected.
event, or loss of Normal f eedwater (if Selected) to (FSAR 15.2.7).
Pressurizer o None Level Pressurfter o Mone Pressure 4
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- 1ABLE IB LOSS OF COMMON INSTRUMENI LIN($
(ASSUMEO BREAK IN LIN()
FAILED FAILURE BOUNOING SE'$0R5 CHANNELS STSitM E1EL(11pN ETFEC1 ACC10 TNT toop Steam Flow to If steam flow selector switched Bounding event 15 End til Feedwater to failed channel, fW valve loss of Norwel FW Carrow Range level Control H1 closes in affected S.G.(s).
(FSAR 15.2.7)
Pressurizer level Ill Prr. Level Control Ni PORY's remain closed. Spray These effects at worst (Centrol )
remains off and heaters turn result in a depres-and on.
If level channel selector suritation which is Przssurtrer Pressure Prr Pressure Control to switch in position I charging.
bounded by inadvertent (PotV 456. 4550)
Ill flow decreases. (On low level. Opening of a Pir. Safety (PORV 455C, Control) lv letdown isolated f rom Inter-or Relief valve lock channel and heaters (FSAR 15.6.1).
blocked). In position 2 level signal not connected, in position 3. letdown is isolated and heaters blocked.
25537:1d/0220e5 28 4
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