ML16120A574
| ML16120A574 | |
| Person / Time | |
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| Site: | Palisades  |
| Issue date: | 04/18/2016 |
| From: | Entergy Nuclear Operations |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16120A302 | List:
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| References | |
| PNP 2016-015 | |
| Download: ML16120A574 (106) | |
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FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-1 of 7.6-21 7.6NUCLEAR STEAM SUPPLY SYSTEM INSTRUMENTATIONThis section primarily describes nonsafety-related instrumentation relevant tothe systems discussed in Sections 7.2, 7.3 and 7.5. Safety-relatedinstrumentation for these sections and Section 7.4 are mentioned only forclarity of text.
7.6.1DESIGN BASES7.6.1.1 Process InstrumentationThe nuclear steam supply system (NSSS) nonnuclear processinstrumentation measures temperatures, pressures, flows and levels in thePrimary Coolant System, secondary system, NSSS auxiliary systems andmeasures containment parameters such as pressure, sump level, hydrogencontent, and gamma radiation. Process variables required on a continuousbasis for start-up, operation and shutdown of the Plant are indicated,recorded and controlled from the control room. Other instrumentation whichis used less frequently or which requires a minimum of operator action islocated near the equipment with remote alarms annunciated in the controlroom. Alternate indicators and controls are located at other locations than thecontrol room to allow reactor shutdown and cooldown should the control roomhave to be evacuated as described in Section 7.4.Four independent measurement channels are provided to monitor eachprocess parameter required for the Reactor Protective System (refer toSection 7.2). Redundant channels are provided for engineered safeguardsaction to meet the single failure criterion (refer to Section 7.3). The fourindependent channels provide sufficient redundancy to ensure system actionand to allow each channel to be tested during Plant operation. Class 1Einstruments listed in Table 5.7-7 are designed to withstand seismic loadsdescribed in Section 5.7 and have been environmentally qualified whenapplicable as described in Chapter 8, Subsection 8.1.3.Two independent channels are provided to monitor parameters required forcritical control functions (refer to Section 7.5).
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-2 of 7.6-217.6.1.2 Nuclear InstrumentationEight channels of instrumentation are provided to monitor the neutron flux.The system consists of four power range safety channels, and two sourcerange channels combined with two wide range channels. The source/widerange channels share high sensitivity fission chambers, enclosure, and powersupply; while the power range channels are completely independent witheach channel complete with separate detectors and power supplies. Eachpower range safety channel is also provided with a rod drop detection circuitand provides calibrated flux, upper and lower signals to its channelizedthermal margin monitor and non-channelized critical function multiplexor. Theoperating range of the eight monitoring channels is greater than ten decadesof neutron flux with channel overlap adequate to monitor the reactor powerfrom shutdown through start-up to 200% of full power(10
-8% to 200% of fullpower). See Figures 7-8 and 7-9 for channel range and overlap.The neutron flux detectors are located in instrument thimbles in the biologicalshield around the reactor vessel. Each start-up and wide-range detector isplaced approximately 180° apart. The power range safety channel detectorsare placed in thimbles approximately every 90° around the core.7.6.1.3 Control Rod Position InstrumentationThe Palisades Plant Computer is a distributed computer system composed ofa host computer and several nodes. Two of these nodes are the PIP nodeand the SPI node. The SPI system, composed of the SPI node plus the hostcomputer, is redundant to the PIP node in the tasks of control rodmeasurement, control rod monitoring, and limits processing.The PIP Node ("PIP") uses the output of a synchro to provide the rod position. Each of the 45 control rods has a synchro. Control rod position is visuallydisplayed on a control room panel. This information is also passed to thehost Computer and to the control room workstation. Position information isalso used to initiate alarms under certain limiting conditions, to providecontact closures for control rod sequencing and control, and to monitor forexcessive control rod position deviation between individual rods within agroup. The PIP is capable of measuring and recording the time for a controlrod to reach bottom after the control rod clutch is released during a controlrod drop test.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-3 of 7.6-21The SPI system ("SPI") consists of the SPI node plus the host computer. TheSPI node functions as an input module and all processing of information isdone in the Host Computer. The SPI node gathers information on the controlrod positions from the reed stack switches. Each of the 45 control rods has areed switch stack. The host computer monitors the various limits associatedwith the control rods. These limits include the PDILs and rod sequencing. Ifa limit is exceeded, an alarm is annunciated on the control room workstation.It does this monitoring using the rod positions from the synchro transducers.If a synchro input card on the PIP were to fail, the host computer would usethe rod position from the SPI input module in the monitoring of rod limits. Thehost computer also compares the position of the rod position from the synchrotransducer and the rod position from the reed stack switches. If there isdeviation in the positions greater than a preset limit, an alarm is annunciatedon the control room workstation.7.6.1.4 Incore InstrumentationThe primary function of the incore instrumentation is to provide measureddata which may be used in evaluating the neutron flux distribution in thereactor core. This data may be used to evaluate thermal margins and toestimate local fuel burnup.The bases for the design of the incore monitors are as follows:
1.Detector assemblies are installed in the reactor core at selectedlocations to obtain core neutron flux and coolant temperatureinformation during reactor operation in the power range.
2.Flux detectors of the self-powered type, with proven capabilities forincore service, are used.
3.The information obtained from the detector assemblies may be usedfor fuel management purposes and to assess the core performance. Itis not used directly for automatic protective or control functions,however it is used for ex-core instrument calibration.
4.The output signal of the flux detectors will be calibrated or adjusted forchanges in sensitivity due to emitter material burnup.
5.The detector assemblies are comprised of local neutron flux detectors(stacked vertically for axial monitoring) and a thermocouple.Axial spacing of the detectors in each assembly and radial spacing of theassemblies permit representative neutron flux mapping of the core andmonitoring of the fuel assembly coolant outlet temperatures.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-4 of 7.6-21The incore instrumentation is required to measure radial peaking factors forTechnical Specifications limits monitoring. This assures that the assumptionsused in the analysis for establishing DNB margin, linear heat rate and theTM/LP and high-power Reactor Protective System trip set points remain validduring operation.The incore instrumentation must also provide a diverse monitoring of reactorcore quadrant power tilt and linear heat rate, both parameters beingmonitored also by the excore nuclear instrumentation (Subsection 7.6.1.2).This diversity of monitoring assures that, in the event of an LOCA, the peakfuel cladding temperature will be acceptable and the minimum DNB will bemaintained above acceptable levels (fuel damage will not exceed acceptablelimits) during anticipated transients. Quadrant power tilt and linear heat rateare limited by Technical Specifications. Linear heat rate is monitored in thecontrol room normally via the incore alarm system. When required, thequadrant power tilt is determined from calculations involving incore detector readings.Sixteen of the incore detectors are provided with electrical connectors andcabling inside containment which has been environmentally qualified to therequirements of IEEE 323-1974. This provides assurance that the sixteencore exit thermocouples (4/core quadrant) will be available to provideindication of the approach to inadequate core cooling conditions followingpostulated accident conditions. Design of these core exit thermocoupleinstrument loops meets the intent of NUREG-0737 and RegulatoryGuide 1.97.7.6.1.5 Palisades Plant Computer (PPC)This monitoring system is provided to display, print, and store plant processinformation. Functions provided include Sequence of Events (SOE)monitoring, Safety Parameter Display System (SPDS) and EmergencyResponse Data-link System (ERDS). It is part of and provides services to thePIP/SPI control rod monitoring system described elsewhere. It provides a linkbetween the Incore neutron inputs and Incore analysis software.Sequences of events for safety- and non-safety-related Plant parameters ofthe following systems are monitored, displayed, and recorded.
1.Reactor Protective System 2.Engineered Safeguards Controls 3.Reactor Shutdown Controls 4.Fluid Systems Protection 5.Regulating Controls 6.Primary Plant Process Instruments 7.Secondary Plant Process Instruments 8.Electrical Power DistributionThe PPC is a non-class 1E monitoring system.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-5 of 7.6-21The PPC includes and conforms to Critical Functions Monitoring System(CFMS) design. This design provides concise display of importantparameters to control room operators. The PPC is designed to provide thesame information to the Technical Support Center (TSC) and EmergencyOperations Facility (EOF) to aid in emergency response management. TheCFMS is a Safety Parameter Display System as described in Supplement 1 toNUREG-0737. In a letter dated April 19, 1990 the NRC found the Palisades'SPDS to be acceptable on the basis that it meets NUREG-0737Supplement 1 requirements (References 11 and 12).The PPC typically interfaces with Class 1E systems through electronicisolation devices, 100K ohm isolation resistors, relay contacts and the CFMSinput termination/ multiplexer cabinets located in the control room. TheCFMS input control cabinets are designed to be seismically qualified to thecriteria of IEEE 344-1975. The CFMS input cabinets also provide forseparation and isolation of Class 1E and Nonclass 1E equipment inaccordance with the requirements of IEEE 384-1977.The SOE node, Cooling Tower Control System (CTCS) node, PIP node, SPInode and the D204 Battery backed power system include componentslocated in the CP Co Design Class l portion of the auxiliary building and, assuch, are required to be housed in cabinets qualified as Seismic Category Iper Regulatory Guide 1.29 to prevent damage to other equipment throughstructural failure. This system has been classified as functional Nonclass 1E,as such interfaces of Class 1E components with the system must meetIEEE 384-1977 and be in accordance with 10 CFR 50, Appendix A, GDC24.
7.6.2SYSTEM DESCRIPTION7.6.2.1 Process InstrumentationThe following process instruments are associated with the reactor protective,reactor control or primary Plant controls. They are safety related or nonsafetyrelated as indicated.Temperature - Temperature measurements are made with precisionresistance temperature detectors (RTDs) which provide a signal to the remotetemperature indicating control and safety devices. Class 1E temperaturechannels in each primary reactor coolant leg are provided power fromseparate preferred ac buses.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-6 of 7.6-21The following is a brief description of each of the temperature measurement channels: 1.Hot Leg Temperatures - Class 1E Each of the two Primary Coolant System hot legs contains four safetygrade temperature measurement channels. Each of these channelsprovides a narrow-range (515°F-615°F) temperature signal to thethermal margin monitors which input to the reactor protection system.Two of these channels on each hot leg also provide wide-range(50°F-700°F) temperature signals to the subcooled margin monitorsdiscussed in Subsection 7.4.6.1.One of these channels from each loop provides narrow range inputthrough an isolation device to the temperature computing station andan indicator as discussed in section 7.5.2.1. Both the narrow-rangeand wide-range signals are obtained from the same RTD through useof a dual-range RTD transmitter.Indications for each of the narrow-range temperature channels areprovided in the control room. Indication of one of the wide-rangetemperature channels on each hot leg is provided in the control roomand at the auxiliary hot shutdown control panel (C-150). Two of thewide-range hot leg temperature channels are also available in theCritical Function Monitoring System (CFMS) computer.
2.Hot Leg Temperature - NonclassA hot leg control grade signal is obtained from a safety channelthrough an isolation device for each hot leg. These channels provide anarrow range signal (515°F 615°F) to the temperature computingstation. Indication of the control grade temperature measurements for each hot leg is provided in the control room. A high temperature alarmis provided by these channels to alert the operator to a hightemperature condition.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-7 of 7.6-21 3.Cold Leg Temperature - Class 1EEach of the four Primary Coolant System cold legs contains two safetygrade temperature measurement channels. Each of these channelsprovides a narrow range (515°F-615°F) temperature signal to thethermal margin monitors which input to the reactor protection system.
A T C alarm is initiated by the thermal margin monitors if the maximummonitors T C (Class 1E) exceeds a T C max or T C min operatoradjustable set point. One of these channels on each cold leg provideswide-range (50°F-700°F) temperature signals to the subcooled marginmonitors discussed in Subsection 7.4.6.1. One of these channels fromeach loop provides narrow range input through an isolation device tothe temperature computing station and an indicator as discussed inSection 7.5.2.1. One of these channels from each loop provides widerange input through an isolation device to LTOP. Both thenarrow-range and wide-range signals are obtained from the same RTDthrough use of a dual-range RTD transmitter.Indications for each of the narrow-range temperature channels areprovided in the control room. Indication of one of the wide-rangetemperature channels from each Primary Coolant System loop is alsoprovided in the control room and at the auxiliary hot shutdown controlpanel (C-150). One wide-range channel from each of the four coldlegs is available in the CFMS computer.
4.Cold Leg Temperature - NonclassA cold leg control grade signal is obtained from a safety channelthrough an isolation device for each cold leg. These channels providea narrow range signal (515°F 615°F) to the temperature computing station.5.Loop Average TemperatureLoop average temperature is computed through the computing stationin each loop. The computing station receives inputs from the controlchannel hot and cold leg temperatures. It outputs to a control roomrecorder.A single recorder provides indications of the temperature outputs ofboth loop computing stations. The recorder provides indication of loopaverage temperature (T AVE), programmed reference temperature (T REF)and loop differential temperatures for each loop.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-8 of 7.6-21 6.Loop Differential TemperatureThe loop differential temperature (Nonclass 1E) is computed from thecontrol channel hot leg and cold leg temperature detector signal. Eachloop differential temperature is recorded in the control room.Pressure - Pressure is measured by electronic pressure transmitters. Thetransmitter produces a dc current output that is proportional to the pressuresensed by the instrument. The dc current outputs are used to provide signalsto the remote pressure indicating control and safety devices.The following is a brief description of each of the pressure measurement channels: 1.Pressurizer Pressure (Protective Action) - Class 1E Four pressurizer pressure transmitters provide independentsuppressed range pressure signals for initiation of Reactor ProtectiveSystem trips on high-pressure and low thermal margin. In addition tothe above trips, signals are provided for initiation of safety injection.These four independent pressure channels provide the signals for theReactor Protective System high-pressure trip and the variable thermalmargin/low-pressure trip. These channels also provide thelow-low-pressure signal to the safety injection units. All four pressurechannels are indicated in the control room and high, low, and low-lowalarms are annunciated. Each channel is provided power from aseparate preferred ac bus.
2.Pressurizer Pressure (Control and Indication) - Class 1ERedundant narrow-range pressure channels are provided foroverpressure interlocks on the suction line valves for shutdowncooling. These interlocks provide additional assurance that thehigh-low pressure interface between the Primary Coolant System andthe Shutdown Cooling System is not breeched when the PrimaryCoolant System is pressurized above the design pressure of theShutdown Cooling System. These narrow-range pressure channelsalso initiate opening of the PORVs (less than 600 psia) when requiredfor overpressure protection of the Primary Coolant System at lowtemperatures (see Subsection 7.4.2.1). Indication and recording ofthese narrow-range pressure channels is provided in the control room. Power to the pressure channels is provided from separate preferred ac buses.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-9 of 7.6-21Redundant wide-range pressure channels initiate opening of thePORVs (greater than or equal to 600 psia) when required foroverpressure protection of PCS at low temperatures and provide forindication of Primary Coolant System pressures as recommended byRegulatory Guide 1.97. Components of these channels located in aharsh environment are qualified to the requirements of IEEE 323-1974to provide assurance that the indicating loops will continue to functionduring post-accident conditions. These pressure channels alsoprovide input to the subcooled margin monitors described inSubsection 7.4.6.1.
3.Pressurizer Pressure (Control and Indication) NonclassTwo independent pressure channels provide suppressed range signalsfor control of the pressurizer heaters and spray valves during normaloperations. The output of either pressure control loop may be selectedfor primary pressure control by a selector switch located in the controlroom. These pressure channels are indicated and recorded in thecontrol room and are powered from independent preferred ac buses.Level - Level is sensed by level transmitters which measure thepressure difference between a reference column of water and thepressurizer water level. This pressure difference is converted to a dccurrent signal proportional to the level of water in the pressurizer. Thedc current outputs of the level transmitters provide signals to theremote level indicating, control and safety devices.The following is a brief description of each of the level measurement channels: 1.Pressurizer Level Two Nonclass 1E independent pressurizer level transmitters providesignals for use by the chemical and volume control charging andletdown system. In addition, signals are provided for pressurizerheater override control. These level transmitters are calibrated forsteam and water densities existing at normal pressurizer operating conditions.The two pressurizer level control channels each provide a signal forrecorders in the control room. One pen records actual level as sensedby the level control channel and the other pen records the programmedlevel set point signal as calculated by the level controller. The recorderalso records pressurizer pressure channels as discussed above.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-10 of 7.6-21One Class 1E pressurizer level transmitter provides a signal to acontrol room indicator. Indication is provided also on the Auxiliary HotShutdown Control Panel C-150. The level transmitter receives powerfrom a preferred ac bus. The level transmitter is calibrated for coldconditions in the Primary Coolant System.Pressurizer level is also measured by a second Class 1E leveltransmitter which indicates in the control room and on the EngineeredSafeguards Auxiliary Panel C-33. This level transmitter is calibratedfor cold conditions in the Primary Coolant System.
2.Steam Generator LevelEach steam generator has four Class 1E narrow-range leveltransmitters for Reactor Protective System channels and twoNonclass 1E transmitters for control function. Each protection channelis provided with physically separated sensing taps. Each channel haslevel indication in the control room. One of the four indications is alsolocated on the Auxiliary Hot Shutdown Control Panel C-150. Inaddition, two Class 1E wide-range level channels per steam generatorare available to ensure proper monitoring of steam generator levelduring operation with auxiliary feedwater (see Subsection 7.4.3.2).Indication from these last channels is located in the control room.Flow - An indication of primary flow is obtained from measurements ofpressure drops across each steam generator. These pressure dropsare sensed by differential pressure transmitters which convert thepressure difference to dc currents. The dc currents provide a signal tothe remote flow indicating and safety devices.The following is a brief description of the flow measurement channels:
1.Primary Coolant Loop Flow RatesFour independent Class 1E differential pressure transmitters areprovided in each loop branch to measure the pressure drop across thesteam generators. The outputs of one of these from each loop branchare summed to provide a signal of flow rate through the reactor core,which is indicated and supplied to the Reactor Protective System forloss-of-flow determination. The differential pressure sensed by eachtransmitter is indicated in the control room. The arrangement of theflow transmitters is shown on Figure 7-6.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-11 of 7.6-217.6.2.2 Nuclear InstrumentationIntroduction - The Nuclear Instrumentation System consists of eight channels.The combined source/wide range channels and power range safety channelsare located in the Reactor Protective System cabinet in the control room.Four cabinets designated as A, B, C and D each house one channel of theprotective system. Cabinets A and B each contain one power range channel.Cabinets C and D each contain one source/wide range channel and onepower range safety channel. Mechanical and thermal barriers between thecabinets reduce the possibility of common event failure. The source andwide-range detector cables of a channel originate from the same preamp andare routed in the same cable tray. Each redundant source/wide rangechannel is separated and fed through different penetrations. The powerrange safety channel detector cables are routed separately from each otherincluding penetration areas. The nuclear detector locations are shown in Figure 7-60.The source range indications are derived from dual independent highsensitivity fission counters. The detector output signals from this dual fissionchamber arrangement are amplified, discriminated and summed at a remotelymounted preamplifier. This conditioned signal is input to the source levelsource rate circuitry located in the control room. Audible count rate signalsare available in the control room and in the containment building.The wide range indications receive signals from one of the dual highsensitivity fission counters used also for source range detection. The detectorsignal is preamplified before input to the count rate and Campbell circuits inthe source/wide range drawer.Four channels are designated as power range safety channels and areconnected to the Reactor Protective System. These channels operate from0% through 125% of full power. Instantaneous nuclear power signals areinput to the Thermal Margin Monitor (TMM) for use in variable high-power trip,thermal margin/ low-pressure set point calculation and axial shape indexalarm. Each of these four channels contains detectors consisting ofdual-section ion chambers which monitor the axial length of the reactor coreat four circumferential positions. They can detect axial flux imbalanceconditions as calculated by the TMM axial shape index alarm. Comparisonbetween the channels allows detection of radial flux imbalance. The gain ofeach power range channel is adjustable to provide a means for calibrating itsoutput against a Plant heat balance.The system is generally designed in accordance with the following criteria:
1.The nuclear instrumentation sensors are located so as to detectrepresentative core flux conditions.
2.Multiple channels are used in all flux ranges.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-12 of 7.6-21 3.The channel ranges overlap sufficiently to assure that the flux iscontinually monitored from source range to 200% of full power.
4.The power range safety channels are classified as 1E and are anintegral part of the Reactor Protective System input channels.
5.Each of the power range safety channels is physically separated fromthe others. Left and right channels of each source/wide range channelare separated from each other.
6.Uninterrupted power is supplied to the system from four separate acbuses. Loss of a channel bus will disable one power range, and in thecase of channels C and D, one source/wide range channel.
7.All channel outputs are buffered so that accidental connection to120 volts ac, or to channel supply voltage, or shorting individualoutputs does not have any effect on any of the other outputs.Source Range Indication - The source range nuclear instrumentation portionuses a pulse signal from a pair of high sensitivity fission chambers. The useof two detector elements within the detector assembly permits high neutronvisibility while operating in gamma fluxes up to 200 rem/h. System reliabilityis improved through the use of integral coaxial detector cables housed in ahigh-pressure moisture barrier. The output of each detector is amplified andsummed in a remotely mounted preamplifier. The pulse signals are alsodiscriminated against gamma pulses and again amplified to drive 300 feet ofcable between the amplifier and signal processing drawer in the control room. Here, the pulse input is converted to a signal proportional to the logarithm ofcount rate. This signal drives a front panel meter, a remote recorder, and aremote meter (all 0.1 cps to 10 5 cps). An audio signal proportional to thecount rate is connected to control room and containment loudspeaker. Thechannel also provides a shaped pulse output for attachment of a scaler.The source range signal is differentiated to provide rate-of-change of powerinformation (-1 to +7 decades/minute). This rate signal feeds a front panelmeter, and a remote meter.Internally generated pulse signals are available for testing count rate circuitryat predetermined cardinal points. A fixed ramp test signal is available fortesting the rate-of-change circuitry.No automatic protective function is assigned to the source rangeinstrumentation portion.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-13 of 7.6-21Wide Range Indication - The wide range nuclear instrumentation portion usesCampbelling techniques and conventional pulse counting techniques topermit the single channel to monitor over 10 decades of flux from 10
-8% fullpower to 200% full power. A single high-sensitivity fission chamber is used as the detecting element. Pulses from the detector pass to a remotelymounted amplifier where they are amplified for transmission to the signalprocessing drawers.The amplifier drives approximately 300 feet of cable between the detector andthe signal processing drawer in the control room. At the signal processingdrawer, the pulse signal is simultaneously applied to two separate detectionand amplification circuits. One circuit consists of a pulse counting circuit.The other circuit uses the ac component of the chamber signal rather than thedc component of the signal.Using Campbell's Theorem, it can be shown that the output of square lawdetection of the ac portion of a random pulse signal is proportional to thepulse rate (see Reference 3). Because square law detection is used, thesmaller gamma pulses produce a very small contribution to the overall signal. Within the mean square portion of the channel, the pulse signal is fed to aband-pass amplifier, a rectifier and filter and a dc log amplifier. Theband-pass amplifier and rectifier provide effective square law detection. Theoutput of the pulse counting type circuit is effective over the first five decades. The mean square circuit is effective over the remaining five decades.By using the two techniques in one channel, a dc signal proportional to thelogarithm of neutron flux over approximately ten decades is obtained. Thissignal drives a front panel meter (10
-8% full power to 200% full power), aremote meter, a remote recorder and trip units.The log level signal is differentiated to provide rate-of-change of powerinformation from -1 to +7 decades/minute. The rate signal feeds a front panelmeter, a remote meter and trip units.Detector high voltage is also monitored by a trip unit which initiates an alarmon decrease of detector voltage or channel trouble.Channel test and calibration are accomplished by internally generated testsignals. Pulse rates controlled by a crystal oscillator, check the count rateportion of the circuitry, and the mean square portion of the circuitry.A ramp signal is available for check of the rate-of-change circuitry.Each source/wide range channel contains eight trip units. Operation of thetrip units is according to Table 7-3.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-14 of 7.6-21The contact output of each trip unit is fed to a single channel of the ReactorProtective System. Thus, with two source/wide range channel portions, aseparate rate trip signal is fed to Channels A, B, C and D of the ReactorProtective System. The < 10
-4% of full power rate-of-change bypass isinitiated by the wide-range channel level signal. The level signal is fed to two trip units set to trip above 10
-4%. Contacts from each trip unit open above 10
-4% to remove the rate trip bypass and enableT power block in TMM viaRelay K26 and to remove the zero power manually actuated bypass associated with a single channel (see Subsection 7.2.5.2).The > 15% full power rate-of-change trip bypass and LPD alarm enable for aparticular channel are initiated by a trip unit in the power range safety channelvia Relay K25. Above 15% full power, the trip unit resets closing a contact ofRelay K25 in parallel with the rate trip contact associated with that channel (A,B, C or D). This method of rate trip bypass permits maximum independenceof rate trip channels.The rate-of-change of power pretrip alarm utilizes a single trip unit (containingtwo sets of relay contacts) in each wide-range logarithmic channel. Each setof contacts feeds an auxiliary trip unit in one of the channels of the ReactorProtective System. The auxiliary trip unit in turn initiates the control rodwithdrawal prohibit signal and pretrip alarm. The signal to the auxiliary tripunit is bypassed below 10
-4% and above 15% of full power to avoid spuriousalarms and control rod withdrawal prohibits.Power Range Safety Channels - The four power range channels measure fluxlinearly over the range of 0% to 125% of full power. The detector assembly consists of two uncompensated ion chambers for each channel. Onedetector extends axially along the lower half of the core while the other, whichis located directly above it, monitors flux from the upper half of the core. Theupper and lower sections have a total active length of 12 feet. The dc currentsignal from each of the ion chambers is fed directly to the control room drawerassembly without preamplification. Integral shielded cable is used within theregion of high neutron and gamma flux.The signal from each chamber (lower and upper detectors, Subchannels Land U, respectively) is fed to independent linear amplifiers (Figure 7-9). Theoutput of each amplifier is indicated, compared and summed. The outputs ofthe L and U subchannels are sent to the thermal margin monitor forcalculation of the ASI function. Internal to the drawers, the subchannelsignals are summed. Signals are sent to the comparator averager, rod dropdetection circuit, remote power level recorder/indicators, critical functionmultiplexor, and thermal margin monitor for VHPT, TM/LP and LPD functioncalculations.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-15 of 7.6-21The output from the comparator averager (grand average) is returned to eachchannel drawer and compared to each channel via two deviationcomparators. Variable deviation set points are calculated from the grandaverage core power in the comparator averager using deviation set pointpotentiometers. The set point signals are entered in the deviationcomparators for alarm setting at two levels. The two levels of deviation arealarmed at the channel drawer and also by remote alarms as percent averagecore power radial (quadrant) flux tilt, Level l, or Level 2, for operator action toensure the Technical Specifications limits on radial peaking factors are observed.The 0%-125% full-scale output of the power range safety channels is fed tothe comparator averager which computes the grand average power level ofall four channels, and to the trip unit which disables the logarithmic channelrate trip above 16.5% full power which also enables theT power in theTMM. The summing circuit also has an X2 gain selector switch which disconnects the input of one ion chamber and doubles the gain for the otherion chamber to allow full-scale power indication should one ion chamber fail.Channel calibration and test is accomplished by an internal current sourcewhich checks amplifier gain and linearity. A check of the level trip set point isprovided by a current signal which is added to the normal detector output.Each power range channel contains a single bistable trip unit set at 15%power. Operation of the trip units is according to Table 7-4.Power Monitoring - In addition to panel meters for decades per minute (DPM)and percent power (logarithmic scale) from, respectively, the start-up andwide-range channels, wide-range linear percent power meters are providedfed from the wide-range channels. All the external metering equipment isconsidered as nonsafety related because it is for operator control informationonly and is isolated from safety-related equipment in accordance withIEEE 384-1977.7.6.2.3 Control Rod Position InstrumentationPIP Node - The PIP node measures control rod positions by use of synchros. Outputs are provided for visual display on the main control board and forcontrol rod control.The major components are:
1.Forty-five control rod position synchros (one per control rod) 2.One node (PIP) containing a VAX computer and an input multiplexer 3.Seven visual displays with seven switches to select control rods within a group FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-16 of 7.6-21The synchro for each control rod is geared to the control rod drive shaft belowthe control rod clutch. Full control rod travel corresponds to 264° of synchrorotation. Synchro output is transmitted to the PIP node which scans andconverts synchro outputs into inches of control rod withdrawal. The resolutionof this system is approximately
+/- 0.5 inch.The PIP, located in the main control room area, performs the followingfunctions:
1.Converts the signal from the synchros to control rod positions andchecks these positions against limiting positions 2.Initiates alarms and interlocks under certain limiting control rodpositions as detailed in Subsection 7.5.2.1 (control rods at upper andlower control rod stops, regulating control rods at prepower and powerdependent insertion limits, 4 inch and 8 inch deviations within a group,and control rod groups out-of-sequence.)
3.Provides contact outputs under other control rod positions as detailedin Subsection 7.5.2.1 (these outputs are used as permissive conditionsin the regulating control rod sequencing controls) 4.Provides visual displays of the control rod positions on the main control board 5.Calculates the control rod drop timesThe operator normally has two means of displaying control rod positions fromthe PIP node:
1.Seven visual displays are mounted above the control rod drive controlson the main control console. There is one display for each control rodgroup; a selector switch at each display will allow position of anycontrol rod in that group to be indicated.
2.The control room workstation. Selected screens on this workstationwill display the synchro rod positions.SPI System - The SPI system ("SPI") consists of the SPI node plus the HostComputer. The SPI node functions as an input multiplexer and all processingof information is done in the Host Computer. The SPI node measures controlrod positions by use of control rod-actuated magnetic reed switches. Thereed switch stack contains a number of series resistors to form a voltagedivider network with reed switches connected at each junction. This stack isattached to the control rod extension housing. A magnet on top of the controlrod extension will actuate the reed switches as the control rod moves. Theoutput signal depends on the particular reed switch that is closed. The signalis directly proportional to control rod position. The resolution of the signal is
+/- 1.5 inches.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-17 of 7.6-21The outputs from all reed stacks are sent to the host computer. The hostcomputer performs the following functions related to the control rods:
1.Initiates alarms under certain limiting control rod positions as detailedin Subsection 7.5.2.1 (control rods at upper and lower control rodstops, regulating control rods at prepower and power dependentinsertion limits, 4 inch and 8 inch deviations within a group, and controlrod groups out-of-sequence.)The SPI system is completely independent of the PIP node as far as rodmonitoring is concerned. If the PIP node were to fail, the SPI system woulduse the reed stacks in monitoring and processing of rod positions and limits.Interlocks and Limit Signals - Limit switches independent of either the PIPnode or SPI system are provided within the control rod drive mechanism.These switches, which are controlled by cams on the control rod synchroshaft, provide shutdown control rod insertion limit signals (interlock functiondiscussed in Subsection 7.5.2.1) and control rod upper and lower electricallimit signals.Additional Control Rod Position Indication - Located on a vertical panelimmediately behind the main control console, is a group of 45 light displaysarranged in a shape corresponding to the control rod distribution. Eachdisplay, which represents one control rod, contains four different coloredlights. These lights give individual control rod information as indicated inTable 7-5.7.6.2.4 Incore InstrumentationThe incore instrumentation consists of a maximum of 43 fixed incore detectorassemblies inserted into selected fuel assemblies. Only 43 incore locationsout of 45 are available; two locations are reserved for use by the reactorvessel level monitoring system. Each incore detector assembly runs thelength of the active core and contains a thermocouple and neutron detectors.Outputs are fed to the SPI node (see Subsection 7.6.2.3) in the control room.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-18 of 7.6-21The thermocouples are of Inconel sheathed, Chromel-Alumel constructionand are located at the top end of each incore detector assembly so that theprimary coolant outlet temperatures may be measured. The neutrondetectors in the assemblies are short rhodium detectors equally spaced.These units with their cabling are contained inside a 0.311-inch nominaldiameter stainless steel sheath. Sixteen of the detectors are provided withenvironmentally qualified electrical connectors and cabling inside containmentto provide increased reliability of the thermocouple readout for monitoring thepotential approach to inadequate core cooling conditions. The readout fromthese thermocouples goes through the Cutler-Hammer (CFMS) multiplexerand not the SPI node. Assemblies are inserted into the core through eightinstrumentation ports in the reactor vessel head. Each assembly is guidedinto position in an empty fuel tube in the center of the fuel assembly via afixed stainless steel guide tube. The seal plug forms a pressure boundary foreach assembly at the reactor vessel head. The neutron detectors produce acurrent proportional to neutron flux by a neutron-beta reaction in the detectorwire. The emitter, which is the central conductor in the coaxial detector, ismade of rhodium and has a high thermal neutron capture cross section. Therhodium detectors are 40 cm long and are provided to measure flux at severalaxial locations in fuel assemblies. Useful life of the rhodium detectors isexpected to be about three years at full power, after which the detectorassemblies will be replaced by new units.The information received by the SPI node is forwarded to the Host Computer.The host computer is where the processing of the incore information occurs.The host:1.Corrects the raw incore values for detector burnup.(A detector background correction is made in the SPI node.)
2.Compares these corrected values to preset alarm limits. Thiscomparison facilitates the monitoring of reactor core radial peakingfactors, quadrant power tilt, and linear heat rate.
3.Initiates an alarm if the limits are exceeded.Verification of incore channel readings and identification of inoperabledetectors are done by correlation between readings and with computed powershapes using a computer program. The incore alarm system operability canbe monitored through the SPI trouble alarm on the main control room panelsand an alarm on the workstations.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-19 of 7.6-21Quadrant power tilt and linear heat rate can be determined from the excorenuclear instrumentation (Subsection 7.6.2.2), provided they are calibratedagainst the incore readings as required by the Technical Specifications.Quadrant power tilt calibrations of the excore readings are performed basedon measured quadrant power tilt calculated using the incore monitoringsystem which determines tilts based on symmetric incore detectors or integralpower in each quadrant of the core (Subsection 3.3.2.5). Linear heat ratecalibration of the excore readings involves two intermediary parameters, axialoffset and allowable power level, which can be determined by the incorereadings. The Technical Specifications give limits on these parametersabove a certain reactor power level to ensure that the core linear heat ratelimits are maintained while using the excore instruments.7.6.2.5 Palisades Plant ComputerSystem Layout - The plant computer consists of four intelligent input nodes,one direct connected multiplexor, multiple display workstations, printers andinterconnecting hardware. The plant computer is a distributed system whichcommunicates via Ethernet. There are separate Ethernet cabling systems forthe Input nodes and for the Man Machine Interfaces.The Man-Machine-Interfaces are Computer Workstations. At the very least,there are workstations in the Control Room, TSC, and EOF. The hostcomputer in the CFMS trailer distributes all database and display informationto the workstations. These workstations maintain a local copy of thedatabase and displays in order to off-load the host. Page printers are locatedin the Control Room (CR), TSC, and EOF for prints of the workstation screensand reports from the host computer.Four input nodes, PIP, SPI, SOE, and CTCS, are combinations of an inputmultiplexor and a computer. These nodes perform input processing includingAnalog to Digital Conversion, Sequence of Events time-stamping, andengineering units conversion. This processed data is assembled and passedto the Host computer. The host computer in turn performs alarm processing,event logging, historical recording and database distribution functions basedon this data. Two nodes, the PIP and CTCS nodes, perform additionalsoftware tasks such that control rod monitoring and Cooling Tower Fans canbe operated independent of host computer operability. The host computerruns several custom software modules such as CFMS processing, Incoremonitoring, Rod monitoring, ERDS, Meteorological computer interface, andcalculated point processing.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-20 of 7.6-21Identification of the PPC components and general location is shown inFigure 7-61. The host computer interfaces, for ERDS, Meteorological, EOF,and the backup alarm printer, are located in the CFMS trailer on the turbinedeck. The communications hubs and the SOE node are located in the Cablespreading room below the control room. The control room has at least onepermanently located workstation and several receptacles where portableworkstation(s) can be connected. A page printer is located here. The PIP,SPI, and CTCS nodes are located in the control room also. The Cutler-Hammer input multiplexor is also located in the control room andcommunicates back to the CFMS trailer directly.The power supply for the PPC host computer and SOE node includes a125 volt dc subsystem (one battery, two chargers and one distribution panel)and a dc-to-ac conversion subsystem (two inverters, two static switches) withbypass transformers. Power is taken from the 480-volt MCCs 3 and 4. Onlythose components required to maintain minimal PPC functionality to theControl room, TSC, and EOF are powered from this system. Extraworkstations and non-essential devices are powered from lighting panelpower. The CTCS node is powered from the Instrument AC panel Y-01, whilethe PIP and SPI nodes are powered from the Preferred AC panels Y-20 andY-40, respectively.Interfaces - The Reactor Protective System is monitored by the SOE node.The interfaces are both analog and digital. Refer to Subsection 7.2.9.2 fordetails. Interfaces with the engineered safeguards controls and the Class 1Eelectrical distribution system are exclusively digital. They are provided viarelay contact inputs from these controls, thus ensuring adequate electricalisolation as required by IEEE 384-1977 and 10 CFR 50, Appendix A, GDC24.Interfaces with the reactor shutdown control, and auxiliary feedwater controlsare also exclusively digital via relay contacts. Interface with the fluid systemsprotection is via relay contact to the SOE Node for PRV-1043B and by directconnection from the valve indicating light to the SOE Node for PRV-1042B.Interfaces with non-safety-related systems (regulating controls, primary andsecondary plant process and Nonclass 1E electrical distribution) are bothdigital and analog. They do not require any special isolation means.The PPC is comprised of reliable electronic gear fed from an uninterruptibletype of power supply. Being a Nonclass 1E system, all safety systemsinterfaces have isolation means in accordance with IEEE 384-1977 andGDC24 either via relay coil-contact isolation or qualified electronic isolators.As described in Section 5.2, components located in the CP Co DesignClass 1 portion of the auxiliary building (the PPC cabinets in the cablespreading room, and certain power supply subsystem components inswitchgear room 1D), have been qualified as Seismic Category I(Section 5.7). The system battery enclosure in switchgear room 1D isequipped with a hydrogen evacuation system, V-928, designed to provide ascavenging rate which precludes the formation of an explosive concentration.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-21 of 7.6-21The CFMS method or design was carried over from the stand alone CFMSreplaced in 1995 into the User interface of the new PPC. The principalsoftware function of the CFMS is to provide concise displays of Plant data,provide for trending of input data and to provide for historical data storage andretrieval. This information is available to system users at each of the variousworkstations. The CFMS software design provides a hierarchy of displaysshowing the status of the Plant's critical safety functions. The hierarchy startswith a top-level display showing individual boxes that give an indication of thestatus of each critical safety function. Lower-level displays give systemoverviews with current values of important process variables and moredetailed mimic diagrams showing system line-up and indicating variables thatare in alarm state by use of color of component symbols or variable values.Displays such as the Critical Function Matrix, event and alarm log, trends andothers can be accessed with dedicated function keys on the keyboard. Asmall representation of the Critical Functions Matrix is visible from everydisplay and indicate the overall status of each critical function.The PPC provides historical storage and retrieval of Process data in order toassist plant personnel in process trending and post-trip or transientrecreations. Historical data can viewed in the form of real-time trends, X-Yplots, and statistical reports. Historical data can be archived to disk or tapefor later viewing. Sequence of events logs are also archived.In addition, the PPC is data linked to the NRC's Emergency ResponseData-link System (ERDS). This data link is capable of sending a preselectedgroup of PPC input variables to the NRC.Additional information on the PPC/CFMS is provided in References 6 and 7.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-1 of 7.6-21 7.6NUCLEAR STEAM SUPPLY SYSTEM INSTRUMENTATIONThis section primarily describes nonsafety-related instrumentation relevant tothe systems discussed in Sections 7.2, 7.3 and 7.5. Safety-relatedinstrumentation for these sections and Section 7.4 are mentioned only forclarity of text.
7.6.1DESIGN BASES7.6.1.1 Process InstrumentationThe nuclear steam supply system (NSSS) nonnuclear processinstrumentation measures temperatures, pressures, flows and levels in thePrimary Coolant System, secondary system, NSSS auxiliary systems andmeasures containment parameters such as pressure, sump level, hydrogencontent, and gamma radiation. Process variables required on a continuousbasis for start-up, operation and shutdown of the Plant are indicated,recorded and controlled from the control room. Other instrumentation whichis used less frequently or which requires a minimum of operator action islocated near the equipment with remote alarms annunciated in the controlroom. Alternate indicators and controls are located at other locations than thecontrol room to allow reactor shutdown and cooldown should the control roomhave to be evacuated as described in Section 7.4.Four independent measurement channels are provided to monitor eachprocess parameter required for the Reactor Protective System (refer toSection 7.2). Redundant channels are provided for engineered safeguardsaction to meet the single failure criterion (refer to Section 7.3). The fourindependent channels provide sufficient redundancy to ensure system actionand to allow each channel to be tested during Plant operation. Class 1Einstruments listed in Table 5.7-7 are designed to withstand seismic loadsdescribed in Section 5.7 and have been environmentally qualified whenapplicable as described in Chapter 8, Subsection 8.1.3.Two independent channels are provided to monitor parameters required forcritical control functions (refer to Section 7.5).
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-2 of 7.6-217.6.1.2 Nuclear InstrumentationEight channels of instrumentation are provided to monitor the neutron flux.The system consists of four power range safety channels, and two sourcerange channels combined with two wide range channels. The source/widerange channels share high sensitivity fission chambers, enclosure, and powersupply; while the power range channels are completely independent witheach channel complete with separate detectors and power supplies. Eachpower range safety channel is also provided with a rod drop detection circuitand provides calibrated flux, upper and lower signals to its channelizedthermal margin monitor and non-channelized critical function multiplexor. Theoperating range of the eight monitoring channels is greater than ten decadesof neutron flux with channel overlap adequate to monitor the reactor powerfrom shutdown through start-up to 200% of full power(10
-8% to 200% of fullpower). See Figures 7-8 and 7-9 for channel range and overlap.The neutron flux detectors are located in instrument thimbles in the biologicalshield around the reactor vessel. Each start-up and wide-range detector isplaced approximately 180° apart. The power range safety channel detectorsare placed in thimbles approximately every 90° around the core.7.6.1.3 Control Rod Position InstrumentationThe Palisades Plant Computer is a distributed computer system composed ofa host computer and several nodes. Two of these nodes are the PIP nodeand the SPI node. The SPI system, composed of the SPI node plus the hostcomputer, is redundant to the PIP node in the tasks of control rodmeasurement, control rod monitoring, and limits processing.The PIP Node ("PIP") uses the output of a synchro to provide the rod position. Each of the 45 control rods has a synchro. Control rod position is visuallydisplayed on a control room panel. This information is also passed to thehost Computer and to the control room workstation. Position information isalso used to initiate alarms under certain limiting conditions, to providecontact closures for control rod sequencing and control, and to monitor forexcessive control rod position deviation between individual rods within agroup. The PIP is capable of measuring and recording the time for a controlrod to reach bottom after the control rod clutch is released during a controlrod drop test.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-3 of 7.6-21The SPI system ("SPI") consists of the SPI node plus the host computer. TheSPI node functions as an input module and all processing of information isdone in the Host Computer. The SPI node gathers information on the controlrod positions from the reed stack switches. Each of the 45 control rods has areed switch stack. The host computer monitors the various limits associatedwith the control rods. These limits include the PDILs and rod sequencing. Ifa limit is exceeded, an alarm is annunciated on the control room workstation.It does this monitoring using the rod positions from the synchro transducers.If a synchro input card on the PIP were to fail, the host computer would usethe rod position from the SPI input module in the monitoring of rod limits. Thehost computer also compares the position of the rod position from the synchrotransducer and the rod position from the reed stack switches. If there isdeviation in the positions greater than a preset limit, an alarm is annunciatedon the control room workstation.7.6.1.4 Incore InstrumentationThe primary function of the incore instrumentation is to provide measureddata which may be used in evaluating the neutron flux distribution in thereactor core. This data may be used to evaluate thermal margins and toestimate local fuel burnup.The bases for the design of the incore monitors are as follows:
1.Detector assemblies are installed in the reactor core at selectedlocations to obtain core neutron flux and coolant temperatureinformation during reactor operation in the power range.
2.Flux detectors of the self-powered type, with proven capabilities forincore service, are used.
3.The information obtained from the detector assemblies may be usedfor fuel management purposes and to assess the core performance. Itis not used directly for automatic protective or control functions,however it is used for ex-core instrument calibration.
4.The output signal of the flux detectors will be calibrated or adjusted forchanges in sensitivity due to emitter material burnup.
5.The detector assemblies are comprised of local neutron flux detectors(stacked vertically for axial monitoring) and a thermocouple.Axial spacing of the detectors in each assembly and radial spacing of theassemblies permit representative neutron flux mapping of the core andmonitoring of the fuel assembly coolant outlet temperatures.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-4 of 7.6-21The incore instrumentation is required to measure radial peaking factors forTechnical Specifications limits monitoring. This assures that the assumptionsused in the analysis for establishing DNB margin, linear heat rate and theTM/LP and high-power Reactor Protective System trip set points remain validduring operation.The incore instrumentation must also provide a diverse monitoring of reactorcore quadrant power tilt and linear heat rate, both parameters beingmonitored also by the excore nuclear instrumentation (Subsection 7.6.1.2).This diversity of monitoring assures that, in the event of an LOCA, the peakfuel cladding temperature will be acceptable and the minimum DNB will bemaintained above acceptable levels (fuel damage will not exceed acceptablelimits) during anticipated transients. Quadrant power tilt and linear heat rateare limited by Technical Specifications. Linear heat rate is monitored in thecontrol room normally via the incore alarm system. When required, thequadrant power tilt is determined from calculations involving incore detector readings.Sixteen of the incore detectors are provided with electrical connectors andcabling inside containment which has been environmentally qualified to therequirements of IEEE 323-1974. This provides assurance that the sixteencore exit thermocouples (4/core quadrant) will be available to provideindication of the approach to inadequate core cooling conditions followingpostulated accident conditions. Design of these core exit thermocoupleinstrument loops meets the intent of NUREG-0737 and RegulatoryGuide 1.97.7.6.1.5 Palisades Plant Computer (PPC)This monitoring system is provided to display, print, and store plant processinformation. Functions provided include Sequence of Events (SOE)monitoring, Safety Parameter Display System (SPDS) and EmergencyResponse Data-link System (ERDS). It is part of and provides services to thePIP/SPI control rod monitoring system described elsewhere. It provides a linkbetween the Incore neutron inputs and Incore analysis software.Sequences of events for safety- and non-safety-related Plant parameters ofthe following systems are monitored, displayed, and recorded.
1.Reactor Protective System 2.Engineered Safeguards Controls 3.Reactor Shutdown Controls 4.Fluid Systems Protection 5.Regulating Controls 6.Primary Plant Process Instruments 7.Secondary Plant Process Instruments 8.Electrical Power DistributionThe PPC is a non-class 1E monitoring system.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-5 of 7.6-21The PPC includes and conforms to Critical Functions Monitoring System(CFMS) design. This design provides concise display of importantparameters to control room operators. The PPC is designed to provide thesame information to the Technical Support Center (TSC) and EmergencyOperations Facility (EOF) to aid in emergency response management. TheCFMS is a Safety Parameter Display System as described in Supplement 1 toNUREG-0737. In a letter dated April 19, 1990 the NRC found the Palisades'SPDS to be acceptable on the basis that it meets NUREG-0737Supplement 1 requirements (References 11 and 12).The PPC typically interfaces with Class 1E systems through electronicisolation devices, 100K ohm isolation resistors, relay contacts and the CFMSinput termination/ multiplexer cabinets located in the control room. TheCFMS input control cabinets are designed to be seismically qualified to thecriteria of IEEE 344-1975. The CFMS input cabinets also provide forseparation and isolation of Class 1E and Nonclass 1E equipment inaccordance with the requirements of IEEE 384-1977.The SOE node, Cooling Tower Control System (CTCS) node, PIP node, SPInode and the D204 Battery backed power system include componentslocated in the CP Co Design Class l portion of the auxiliary building and, assuch, are required to be housed in cabinets qualified as Seismic Category Iper Regulatory Guide 1.29 to prevent damage to other equipment throughstructural failure. This system has been classified as functional Nonclass 1E,as such interfaces of Class 1E components with the system must meetIEEE 384-1977 and be in accordance with 10 CFR 50, Appendix A, GDC24.
7.6.2SYSTEM DESCRIPTION7.6.2.1 Process InstrumentationThe following process instruments are associated with the reactor protective,reactor control or primary Plant controls. They are safety related or nonsafetyrelated as indicated.Temperature - Temperature measurements are made with precisionresistance temperature detectors (RTDs) which provide a signal to the remotetemperature indicating control and safety devices. Class 1E temperaturechannels in each primary reactor coolant leg are provided power fromseparate preferred ac buses.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-6 of 7.6-21The following is a brief description of each of the temperature measurement channels: 1.Hot Leg Temperatures - Class 1E Each of the two Primary Coolant System hot legs contains four safetygrade temperature measurement channels. Each of these channelsprovides a narrow-range (515°F-615°F) temperature signal to thethermal margin monitors which input to the reactor protection system.Two of these channels on each hot leg also provide wide-range(50°F-700°F) temperature signals to the subcooled margin monitorsdiscussed in Subsection 7.4.6.1.One of these channels from each loop provides narrow range inputthrough an isolation device to the temperature computing station andan indicator as discussed in section 7.5.2.1. Both the narrow-rangeand wide-range signals are obtained from the same RTD through useof a dual-range RTD transmitter.Indications for each of the narrow-range temperature channels areprovided in the control room. Indication of one of the wide-rangetemperature channels on each hot leg is provided in the control roomand at the auxiliary hot shutdown control panel (C-150). Two of thewide-range hot leg temperature channels are also available in theCritical Function Monitoring System (CFMS) computer.
2.Hot Leg Temperature - NonclassA hot leg control grade signal is obtained from a safety channelthrough an isolation device for each hot leg. These channels provide anarrow range signal (515°F 615°F) to the temperature computingstation. Indication of the control grade temperature measurements for each hot leg is provided in the control room. A high temperature alarmis provided by these channels to alert the operator to a hightemperature condition.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-7 of 7.6-21 3.Cold Leg Temperature - Class 1EEach of the four Primary Coolant System cold legs contains two safetygrade temperature measurement channels. Each of these channelsprovides a narrow range (515°F-615°F) temperature signal to thethermal margin monitors which input to the reactor protection system.
A T C alarm is initiated by the thermal margin monitors if the maximummonitors T C (Class 1E) exceeds a T C max or T C min operatoradjustable set point. One of these channels on each cold leg provideswide-range (50°F-700°F) temperature signals to the subcooled marginmonitors discussed in Subsection 7.4.6.1. One of these channels fromeach loop provides narrow range input through an isolation device tothe temperature computing station and an indicator as discussed inSection 7.5.2.1. One of these channels from each loop provides widerange input through an isolation device to LTOP. Both thenarrow-range and wide-range signals are obtained from the same RTDthrough use of a dual-range RTD transmitter.Indications for each of the narrow-range temperature channels areprovided in the control room. Indication of one of the wide-rangetemperature channels from each Primary Coolant System loop is alsoprovided in the control room and at the auxiliary hot shutdown controlpanel (C-150). One wide-range channel from each of the four coldlegs is available in the CFMS computer.
4.Cold Leg Temperature - NonclassA cold leg control grade signal is obtained from a safety channelthrough an isolation device for each cold leg. These channels providea narrow range signal (515°F 615°F) to the temperature computing station.5.Loop Average TemperatureLoop average temperature is computed through the computing stationin each loop. The computing station receives inputs from the controlchannel hot and cold leg temperatures. It outputs to a control roomrecorder.A single recorder provides indications of the temperature outputs ofboth loop computing stations. The recorder provides indication of loopaverage temperature (T AVE), programmed reference temperature (T REF)and loop differential temperatures for each loop.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-8 of 7.6-21 6.Loop Differential TemperatureThe loop differential temperature (Nonclass 1E) is computed from thecontrol channel hot leg and cold leg temperature detector signal. Eachloop differential temperature is recorded in the control room.Pressure - Pressure is measured by electronic pressure transmitters. Thetransmitter produces a dc current output that is proportional to the pressuresensed by the instrument. The dc current outputs are used to provide signalsto the remote pressure indicating control and safety devices.The following is a brief description of each of the pressure measurement channels: 1.Pressurizer Pressure (Protective Action) - Class 1E Four pressurizer pressure transmitters provide independentsuppressed range pressure signals for initiation of Reactor ProtectiveSystem trips on high-pressure and low thermal margin. In addition tothe above trips, signals are provided for initiation of safety injection.These four independent pressure channels provide the signals for theReactor Protective System high-pressure trip and the variable thermalmargin/low-pressure trip. These channels also provide thelow-low-pressure signal to the safety injection units. All four pressurechannels are indicated in the control room and high, low, and low-lowalarms are annunciated. Each channel is provided power from aseparate preferred ac bus.
2.Pressurizer Pressure (Control and Indication) - Class 1ERedundant narrow-range pressure channels are provided foroverpressure interlocks on the suction line valves for shutdowncooling. These interlocks provide additional assurance that thehigh-low pressure interface between the Primary Coolant System andthe Shutdown Cooling System is not breeched when the PrimaryCoolant System is pressurized above the design pressure of theShutdown Cooling System. These narrow-range pressure channelsalso initiate opening of the PORVs (less than 600 psia) when requiredfor overpressure protection of the Primary Coolant System at lowtemperatures (see Subsection 7.4.2.1). Indication and recording ofthese narrow-range pressure channels is provided in the control room. Power to the pressure channels is provided from separate preferred ac buses.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-9 of 7.6-21Redundant wide-range pressure channels initiate opening of thePORVs (greater than or equal to 600 psia) when required foroverpressure protection of PCS at low temperatures and provide forindication of Primary Coolant System pressures as recommended byRegulatory Guide 1.97. Components of these channels located in aharsh environment are qualified to the requirements of IEEE 323-1974to provide assurance that the indicating loops will continue to functionduring post-accident conditions. These pressure channels alsoprovide input to the subcooled margin monitors described inSubsection 7.4.6.1.
3.Pressurizer Pressure (Control and Indication) NonclassTwo independent pressure channels provide suppressed range signalsfor control of the pressurizer heaters and spray valves during normaloperations. The output of either pressure control loop may be selectedfor primary pressure control by a selector switch located in the controlroom. These pressure channels are indicated and recorded in thecontrol room and are powered from independent preferred ac buses.Level - Level is sensed by level transmitters which measure thepressure difference between a reference column of water and thepressurizer water level. This pressure difference is converted to a dccurrent signal proportional to the level of water in the pressurizer. Thedc current outputs of the level transmitters provide signals to theremote level indicating, control and safety devices.The following is a brief description of each of the level measurement channels: 1.Pressurizer Level Two Nonclass 1E independent pressurizer level transmitters providesignals for use by the chemical and volume control charging andletdown system. In addition, signals are provided for pressurizerheater override control. These level transmitters are calibrated forsteam and water densities existing at normal pressurizer operating conditions.The two pressurizer level control channels each provide a signal forrecorders in the control room. One pen records actual level as sensedby the level control channel and the other pen records the programmedlevel set point signal as calculated by the level controller. The recorderalso records pressurizer pressure channels as discussed above.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-10 of 7.6-21One Class 1E pressurizer level transmitter provides a signal to acontrol room indicator. Indication is provided also on the Auxiliary HotShutdown Control Panel C-150. The level transmitter receives powerfrom a preferred ac bus. The level transmitter is calibrated for coldconditions in the Primary Coolant System.Pressurizer level is also measured by a second Class 1E leveltransmitter which indicates in the control room and on the EngineeredSafeguards Auxiliary Panel C-33. This level transmitter is calibratedfor cold conditions in the Primary Coolant System.
2.Steam Generator LevelEach steam generator has four Class 1E narrow-range leveltransmitters for Reactor Protective System channels and twoNonclass 1E transmitters for control function. Each protection channelis provided with physically separated sensing taps. Each channel haslevel indication in the control room. One of the four indications is alsolocated on the Auxiliary Hot Shutdown Control Panel C-150. Inaddition, two Class 1E wide-range level channels per steam generatorare available to ensure proper monitoring of steam generator levelduring operation with auxiliary feedwater (see Subsection 7.4.3.2).Indication from these last channels is located in the control room.Flow - An indication of primary flow is obtained from measurements ofpressure drops across each steam generator. These pressure dropsare sensed by differential pressure transmitters which convert thepressure difference to dc currents. The dc currents provide a signal tothe remote flow indicating and safety devices.The following is a brief description of the flow measurement channels:
1.Primary Coolant Loop Flow RatesFour independent Class 1E differential pressure transmitters areprovided in each loop branch to measure the pressure drop across thesteam generators. The outputs of one of these from each loop branchare summed to provide a signal of flow rate through the reactor core,which is indicated and supplied to the Reactor Protective System forloss-of-flow determination. The differential pressure sensed by eachtransmitter is indicated in the control room. The arrangement of theflow transmitters is shown on Figure 7-6.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-11 of 7.6-217.6.2.2 Nuclear InstrumentationIntroduction - The Nuclear Instrumentation System consists of eight channels.The combined source/wide range channels and power range safety channelsare located in the Reactor Protective System cabinet in the control room.Four cabinets designated as A, B, C and D each house one channel of theprotective system. Cabinets A and B each contain one power range channel.Cabinets C and D each contain one source/wide range channel and onepower range safety channel. Mechanical and thermal barriers between thecabinets reduce the possibility of common event failure. The source andwide-range detector cables of a channel originate from the same preamp andare routed in the same cable tray. Each redundant source/wide rangechannel is separated and fed through different penetrations. The powerrange safety channel detector cables are routed separately from each otherincluding penetration areas. The nuclear detector locations are shown in Figure 7-60.The source range indications are derived from dual independent highsensitivity fission counters. The detector output signals from this dual fissionchamber arrangement are amplified, discriminated and summed at a remotelymounted preamplifier. This conditioned signal is input to the source levelsource rate circuitry located in the control room. Audible count rate signalsare available in the control room and in the containment building.The wide range indications receive signals from one of the dual highsensitivity fission counters used also for source range detection. The detectorsignal is preamplified before input to the count rate and Campbell circuits inthe source/wide range drawer.Four channels are designated as power range safety channels and areconnected to the Reactor Protective System. These channels operate from0% through 125% of full power. Instantaneous nuclear power signals areinput to the Thermal Margin Monitor (TMM) for use in variable high-power trip,thermal margin/ low-pressure set point calculation and axial shape indexalarm. Each of these four channels contains detectors consisting ofdual-section ion chambers which monitor the axial length of the reactor coreat four circumferential positions. They can detect axial flux imbalanceconditions as calculated by the TMM axial shape index alarm. Comparisonbetween the channels allows detection of radial flux imbalance. The gain ofeach power range channel is adjustable to provide a means for calibrating itsoutput against a Plant heat balance.The system is generally designed in accordance with the following criteria:
1.The nuclear instrumentation sensors are located so as to detectrepresentative core flux conditions.
2.Multiple channels are used in all flux ranges.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-12 of 7.6-21 3.The channel ranges overlap sufficiently to assure that the flux iscontinually monitored from source range to 200% of full power.
4.The power range safety channels are classified as 1E and are anintegral part of the Reactor Protective System input channels.
5.Each of the power range safety channels is physically separated fromthe others. Left and right channels of each source/wide range channelare separated from each other.
6.Uninterrupted power is supplied to the system from four separate acbuses. Loss of a channel bus will disable one power range, and in thecase of channels C and D, one source/wide range channel.
7.All channel outputs are buffered so that accidental connection to120 volts ac, or to channel supply voltage, or shorting individualoutputs does not have any effect on any of the other outputs.Source Range Indication - The source range nuclear instrumentation portionuses a pulse signal from a pair of high sensitivity fission chambers. The useof two detector elements within the detector assembly permits high neutronvisibility while operating in gamma fluxes up to 200 rem/h. System reliabilityis improved through the use of integral coaxial detector cables housed in ahigh-pressure moisture barrier. The output of each detector is amplified andsummed in a remotely mounted preamplifier. The pulse signals are alsodiscriminated against gamma pulses and again amplified to drive 300 feet ofcable between the amplifier and signal processing drawer in the control room. Here, the pulse input is converted to a signal proportional to the logarithm ofcount rate. This signal drives a front panel meter, a remote recorder, and aremote meter (all 0.1 cps to 10 5 cps). An audio signal proportional to thecount rate is connected to control room and containment loudspeaker. Thechannel also provides a shaped pulse output for attachment of a scaler.The source range signal is differentiated to provide rate-of-change of powerinformation (-1 to +7 decades/minute). This rate signal feeds a front panelmeter, and a remote meter.Internally generated pulse signals are available for testing count rate circuitryat predetermined cardinal points. A fixed ramp test signal is available fortesting the rate-of-change circuitry.No automatic protective function is assigned to the source rangeinstrumentation portion.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-13 of 7.6-21Wide Range Indication - The wide range nuclear instrumentation portion usesCampbelling techniques and conventional pulse counting techniques topermit the single channel to monitor over 10 decades of flux from 10
-8% fullpower to 200% full power. A single high-sensitivity fission chamber is used as the detecting element. Pulses from the detector pass to a remotelymounted amplifier where they are amplified for transmission to the signalprocessing drawers.The amplifier drives approximately 300 feet of cable between the detector andthe signal processing drawer in the control room. At the signal processingdrawer, the pulse signal is simultaneously applied to two separate detectionand amplification circuits. One circuit consists of a pulse counting circuit.The other circuit uses the ac component of the chamber signal rather than thedc component of the signal.Using Campbell's Theorem, it can be shown that the output of square lawdetection of the ac portion of a random pulse signal is proportional to thepulse rate (see Reference 3). Because square law detection is used, thesmaller gamma pulses produce a very small contribution to the overall signal. Within the mean square portion of the channel, the pulse signal is fed to aband-pass amplifier, a rectifier and filter and a dc log amplifier. Theband-pass amplifier and rectifier provide effective square law detection. Theoutput of the pulse counting type circuit is effective over the first five decades. The mean square circuit is effective over the remaining five decades.By using the two techniques in one channel, a dc signal proportional to thelogarithm of neutron flux over approximately ten decades is obtained. Thissignal drives a front panel meter (10
-8% full power to 200% full power), aremote meter, a remote recorder and trip units.The log level signal is differentiated to provide rate-of-change of powerinformation from -1 to +7 decades/minute. The rate signal feeds a front panelmeter, a remote meter and trip units.Detector high voltage is also monitored by a trip unit which initiates an alarmon decrease of detector voltage or channel trouble.Channel test and calibration are accomplished by internally generated testsignals. Pulse rates controlled by a crystal oscillator, check the count rateportion of the circuitry, and the mean square portion of the circuitry.A ramp signal is available for check of the rate-of-change circuitry.Each source/wide range channel contains eight trip units. Operation of thetrip units is according to Table 7-3.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-14 of 7.6-21The contact output of each trip unit is fed to a single channel of the ReactorProtective System. Thus, with two source/wide range channel portions, aseparate rate trip signal is fed to Channels A, B, C and D of the ReactorProtective System. The < 10
-4% of full power rate-of-change bypass isinitiated by the wide-range channel level signal. The level signal is fed to two trip units set to trip above 10
-4%. Contacts from each trip unit open above 10
-4% to remove the rate trip bypass and enableT power block in TMM viaRelay K26 and to remove the zero power manually actuated bypass associated with a single channel (see Subsection 7.2.5.2).The > 15% full power rate-of-change trip bypass and LPD alarm enable for aparticular channel are initiated by a trip unit in the power range safety channelvia Relay K25. Above 15% full power, the trip unit resets closing a contact ofRelay K25 in parallel with the rate trip contact associated with that channel (A,B, C or D). This method of rate trip bypass permits maximum independenceof rate trip channels.The rate-of-change of power pretrip alarm utilizes a single trip unit (containingtwo sets of relay contacts) in each wide-range logarithmic channel. Each setof contacts feeds an auxiliary trip unit in one of the channels of the ReactorProtective System. The auxiliary trip unit in turn initiates the control rodwithdrawal prohibit signal and pretrip alarm. The signal to the auxiliary tripunit is bypassed below 10
-4% and above 15% of full power to avoid spuriousalarms and control rod withdrawal prohibits.Power Range Safety Channels - The four power range channels measure fluxlinearly over the range of 0% to 125% of full power. The detector assembly consists of two uncompensated ion chambers for each channel. Onedetector extends axially along the lower half of the core while the other, whichis located directly above it, monitors flux from the upper half of the core. Theupper and lower sections have a total active length of 12 feet. The dc currentsignal from each of the ion chambers is fed directly to the control room drawerassembly without preamplification. Integral shielded cable is used within theregion of high neutron and gamma flux.The signal from each chamber (lower and upper detectors, Subchannels Land U, respectively) is fed to independent linear amplifiers (Figure 7-9). Theoutput of each amplifier is indicated, compared and summed. The outputs ofthe L and U subchannels are sent to the thermal margin monitor forcalculation of the ASI function. Internal to the drawers, the subchannelsignals are summed. Signals are sent to the comparator averager, rod dropdetection circuit, remote power level recorder/indicators, critical functionmultiplexor, and thermal margin monitor for VHPT, TM/LP and LPD functioncalculations.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-15 of 7.6-21The output from the comparator averager (grand average) is returned to eachchannel drawer and compared to each channel via two deviationcomparators. Variable deviation set points are calculated from the grandaverage core power in the comparator averager using deviation set pointpotentiometers. The set point signals are entered in the deviationcomparators for alarm setting at two levels. The two levels of deviation arealarmed at the channel drawer and also by remote alarms as percent averagecore power radial (quadrant) flux tilt, Level l, or Level 2, for operator action toensure the Technical Specifications limits on radial peaking factors are observed.The 0%-125% full-scale output of the power range safety channels is fed tothe comparator averager which computes the grand average power level ofall four channels, and to the trip unit which disables the logarithmic channelrate trip above 16.5% full power which also enables theT power in theTMM. The summing circuit also has an X2 gain selector switch which disconnects the input of one ion chamber and doubles the gain for the otherion chamber to allow full-scale power indication should one ion chamber fail.Channel calibration and test is accomplished by an internal current sourcewhich checks amplifier gain and linearity. A check of the level trip set point isprovided by a current signal which is added to the normal detector output.Each power range channel contains a single bistable trip unit set at 15%power. Operation of the trip units is according to Table 7-4.Power Monitoring - In addition to panel meters for decades per minute (DPM)and percent power (logarithmic scale) from, respectively, the start-up andwide-range channels, wide-range linear percent power meters are providedfed from the wide-range channels. All the external metering equipment isconsidered as nonsafety related because it is for operator control informationonly and is isolated from safety-related equipment in accordance withIEEE 384-1977.7.6.2.3 Control Rod Position InstrumentationPIP Node - The PIP node measures control rod positions by use of synchros. Outputs are provided for visual display on the main control board and forcontrol rod control.The major components are:
1.Forty-five control rod position synchros (one per control rod) 2.One node (PIP) containing a VAX computer and an input multiplexer 3.Seven visual displays with seven switches to select control rods within a group FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-16 of 7.6-21The synchro for each control rod is geared to the control rod drive shaft belowthe control rod clutch. Full control rod travel corresponds to 264° of synchrorotation. Synchro output is transmitted to the PIP node which scans andconverts synchro outputs into inches of control rod withdrawal. The resolutionof this system is approximately
+/- 0.5 inch.The PIP, located in the main control room area, performs the followingfunctions:
1.Converts the signal from the synchros to control rod positions andchecks these positions against limiting positions 2.Initiates alarms and interlocks under certain limiting control rodpositions as detailed in Subsection 7.5.2.1 (control rods at upper andlower control rod stops, regulating control rods at prepower and powerdependent insertion limits, 4 inch and 8 inch deviations within a group,and control rod groups out-of-sequence.)
3.Provides contact outputs under other control rod positions as detailedin Subsection 7.5.2.1 (these outputs are used as permissive conditionsin the regulating control rod sequencing controls) 4.Provides visual displays of the control rod positions on the main control board 5.Calculates the control rod drop timesThe operator normally has two means of displaying control rod positions fromthe PIP node:
1.Seven visual displays are mounted above the control rod drive controlson the main control console. There is one display for each control rodgroup; a selector switch at each display will allow position of anycontrol rod in that group to be indicated.
2.The control room workstation. Selected screens on this workstationwill display the synchro rod positions.SPI System - The SPI system ("SPI") consists of the SPI node plus the HostComputer. The SPI node functions as an input multiplexer and all processingof information is done in the Host Computer. The SPI node measures controlrod positions by use of control rod-actuated magnetic reed switches. Thereed switch stack contains a number of series resistors to form a voltagedivider network with reed switches connected at each junction. This stack isattached to the control rod extension housing. A magnet on top of the controlrod extension will actuate the reed switches as the control rod moves. Theoutput signal depends on the particular reed switch that is closed. The signalis directly proportional to control rod position. The resolution of the signal is
+/- 1.5 inches.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-17 of 7.6-21The outputs from all reed stacks are sent to the host computer. The hostcomputer performs the following functions related to the control rods:
1.Initiates alarms under certain limiting control rod positions as detailedin Subsection 7.5.2.1 (control rods at upper and lower control rodstops, regulating control rods at prepower and power dependentinsertion limits, 4 inch and 8 inch deviations within a group, and controlrod groups out-of-sequence.)The SPI system is completely independent of the PIP node as far as rodmonitoring is concerned. If the PIP node were to fail, the SPI system woulduse the reed stacks in monitoring and processing of rod positions and limits.Interlocks and Limit Signals - Limit switches independent of either the PIPnode or SPI system are provided within the control rod drive mechanism.These switches, which are controlled by cams on the control rod synchroshaft, provide shutdown control rod insertion limit signals (interlock functiondiscussed in Subsection 7.5.2.1) and control rod upper and lower electricallimit signals.Additional Control Rod Position Indication - Located on a vertical panelimmediately behind the main control console, is a group of 45 light displaysarranged in a shape corresponding to the control rod distribution. Eachdisplay, which represents one control rod, contains four different coloredlights. These lights give individual control rod information as indicated inTable 7-5.7.6.2.4 Incore InstrumentationThe incore instrumentation consists of a maximum of 43 fixed incore detectorassemblies inserted into selected fuel assemblies. Only 43 incore locationsout of 45 are available; two locations are reserved for use by the reactorvessel level monitoring system. Each incore detector assembly runs thelength of the active core and contains a thermocouple and neutron detectors.Outputs are fed to the SPI node (see Subsection 7.6.2.3) in the control room.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-18 of 7.6-21The thermocouples are of Inconel sheathed, Chromel-Alumel constructionand are located at the top end of each incore detector assembly so that theprimary coolant outlet temperatures may be measured. The neutrondetectors in the assemblies are short rhodium detectors equally spaced.These units with their cabling are contained inside a 0.311-inch nominaldiameter stainless steel sheath. Sixteen of the detectors are provided withenvironmentally qualified electrical connectors and cabling inside containmentto provide increased reliability of the thermocouple readout for monitoring thepotential approach to inadequate core cooling conditions. The readout fromthese thermocouples goes through the Cutler-Hammer (CFMS) multiplexerand not the SPI node. Assemblies are inserted into the core through eightinstrumentation ports in the reactor vessel head. Each assembly is guidedinto position in an empty fuel tube in the center of the fuel assembly via afixed stainless steel guide tube. The seal plug forms a pressure boundary foreach assembly at the reactor vessel head. The neutron detectors produce acurrent proportional to neutron flux by a neutron-beta reaction in the detectorwire. The emitter, which is the central conductor in the coaxial detector, ismade of rhodium and has a high thermal neutron capture cross section. Therhodium detectors are 40 cm long and are provided to measure flux at severalaxial locations in fuel assemblies. Useful life of the rhodium detectors isexpected to be about three years at full power, after which the detectorassemblies will be replaced by new units.The information received by the SPI node is forwarded to the Host Computer.The host computer is where the processing of the incore information occurs.The host:1.Corrects the raw incore values for detector burnup.(A detector background correction is made in the SPI node.)
2.Compares these corrected values to preset alarm limits. Thiscomparison facilitates the monitoring of reactor core radial peakingfactors, quadrant power tilt, and linear heat rate.
3.Initiates an alarm if the limits are exceeded.Verification of incore channel readings and identification of inoperabledetectors are done by correlation between readings and with computed powershapes using a computer program. The incore alarm system operability canbe monitored through the SPI trouble alarm on the main control room panelsand an alarm on the workstations.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-19 of 7.6-21Quadrant power tilt and linear heat rate can be determined from the excorenuclear instrumentation (Subsection 7.6.2.2), provided they are calibratedagainst the incore readings as required by the Technical Specifications.Quadrant power tilt calibrations of the excore readings are performed basedon measured quadrant power tilt calculated using the incore monitoringsystem which determines tilts based on symmetric incore detectors or integralpower in each quadrant of the core (Subsection 3.3.2.5). Linear heat ratecalibration of the excore readings involves two intermediary parameters, axialoffset and allowable power level, which can be determined by the incorereadings. The Technical Specifications give limits on these parametersabove a certain reactor power level to ensure that the core linear heat ratelimits are maintained while using the excore instruments.7.6.2.5 Palisades Plant ComputerSystem Layout - The plant computer consists of four intelligent input nodes,one direct connected multiplexor, multiple display workstations, printers andinterconnecting hardware. The plant computer is a distributed system whichcommunicates via Ethernet. There are separate Ethernet cabling systems forthe Input nodes and for the Man Machine Interfaces.The Man-Machine-Interfaces are Computer Workstations. At the very least,there are workstations in the Control Room, TSC, and EOF. The hostcomputer in the CFMS trailer distributes all database and display informationto the workstations. These workstations maintain a local copy of thedatabase and displays in order to off-load the host. Page printers are locatedin the Control Room (CR), TSC, and EOF for prints of the workstation screensand reports from the host computer.Four input nodes, PIP, SPI, SOE, and CTCS, are combinations of an inputmultiplexor and a computer. These nodes perform input processing includingAnalog to Digital Conversion, Sequence of Events time-stamping, andengineering units conversion. This processed data is assembled and passedto the Host computer. The host computer in turn performs alarm processing,event logging, historical recording and database distribution functions basedon this data. Two nodes, the PIP and CTCS nodes, perform additionalsoftware tasks such that control rod monitoring and Cooling Tower Fans canbe operated independent of host computer operability. The host computerruns several custom software modules such as CFMS processing, Incoremonitoring, Rod monitoring, ERDS, Meteorological computer interface, andcalculated point processing.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-20 of 7.6-21Identification of the PPC components and general location is shown inFigure 7-61. The host computer interfaces, for ERDS, Meteorological, EOF,and the backup alarm printer, are located in the CFMS trailer on the turbinedeck. The communications hubs and the SOE node are located in the Cablespreading room below the control room. The control room has at least onepermanently located workstation and several receptacles where portableworkstation(s) can be connected. A page printer is located here. The PIP,SPI, and CTCS nodes are located in the control room also. The Cutler-Hammer input multiplexor is also located in the control room andcommunicates back to the CFMS trailer directly.The power supply for the PPC host computer and SOE node includes a125 volt dc subsystem (one battery, two chargers and one distribution panel)and a dc-to-ac conversion subsystem (two inverters, two static switches) withbypass transformers. Power is taken from the 480-volt MCCs 3 and 4. Onlythose components required to maintain minimal PPC functionality to theControl room, TSC, and EOF are powered from this system. Extraworkstations and non-essential devices are powered from lighting panelpower. The CTCS node is powered from the Instrument AC panel Y-01, whilethe PIP and SPI nodes are powered from the Preferred AC panels Y-20 andY-40, respectively.Interfaces - The Reactor Protective System is monitored by the SOE node.The interfaces are both analog and digital. Refer to Subsection 7.2.9.2 fordetails. Interfaces with the engineered safeguards controls and the Class 1Eelectrical distribution system are exclusively digital. They are provided viarelay contact inputs from these controls, thus ensuring adequate electricalisolation as required by IEEE 384-1977 and 10 CFR 50, Appendix A, GDC24.Interfaces with the reactor shutdown control, and auxiliary feedwater controlsare also exclusively digital via relay contacts. Interface with the fluid systemsprotection is via relay contact to the SOE Node for PRV-1043B and by directconnection from the valve indicating light to the SOE Node for PRV-1042B.Interfaces with non-safety-related systems (regulating controls, primary andsecondary plant process and Nonclass 1E electrical distribution) are bothdigital and analog. They do not require any special isolation means.The PPC is comprised of reliable electronic gear fed from an uninterruptibletype of power supply. Being a Nonclass 1E system, all safety systemsinterfaces have isolation means in accordance with IEEE 384-1977 andGDC24 either via relay coil-contact isolation or qualified electronic isolators.As described in Section 5.2, components located in the CP Co DesignClass 1 portion of the auxiliary building (the PPC cabinets in the cablespreading room, and certain power supply subsystem components inswitchgear room 1D), have been qualified as Seismic Category I(Section 5.7). The system battery enclosure in switchgear room 1D isequipped with a hydrogen evacuation system, V-928, designed to provide ascavenging rate which precludes the formation of an explosive concentration.
FSAR CHAPTER 7 - INSTRUMENTATION AND CONTROLSRevision 30SECTION 7.6Page 7.6-21 of 7.6-21The CFMS method or design was carried over from the stand alone CFMSreplaced in 1995 into the User interface of the new PPC. The principalsoftware function of the CFMS is to provide concise displays of Plant data,provide for trending of input data and to provide for historical data storage andretrieval. This information is available to system users at each of the variousworkstations. The CFMS software design provides a hierarchy of displaysshowing the status of the Plant's critical safety functions. The hierarchy startswith a top-level display showing individual boxes that give an indication of thestatus of each critical safety function. Lower-level displays give systemoverviews with current values of important process variables and moredetailed mimic diagrams showing system line-up and indicating variables thatare in alarm state by use of color of component symbols or variable values.Displays such as the Critical Function Matrix, event and alarm log, trends andothers can be accessed with dedicated function keys on the keyboard. Asmall representation of the Critical Functions Matrix is visible from everydisplay and indicate the overall status of each critical function.The PPC provides historical storage and retrieval of Process data in order toassist plant personnel in process trending and post-trip or transientrecreations. Historical data can viewed in the form of real-time trends, X-Yplots, and statistical reports. Historical data can be archived to disk or tapefor later viewing. Sequence of events logs are also archived.In addition, the PPC is data linked to the NRC's Emergency ResponseData-link System (ERDS). This data link is capable of sending a preselectedgroup of PPC input variables to the NRC.Additional information on the PPC/CFMS is provided in References 6 and 7.