ML14078A636

Phase 0 2014-Mar-06 Review of Digital I+C Upgrade (El NRC Presentation) Rev-Mar 4 Redacted

ML14078A636
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	03/06/2014
From:	Lau E S Massachusetts Institute of Technology (MIT)
To:	Office of Nuclear Reactor Regulation
Hardesty D A
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ML14078A659	List: ML14078A545 ML14078A636
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Download: ML14078A636 (25)

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MITResearchReactorMIT Research ReactorEdward S. LauAssistant Director of Reactor OperationsMIT Nuclear Reactor LaboratoryPhase 0 Review of MITR ApproachtoaDigitalI&CUpgradeto a Digital I&C UpgradeMarch62014March 6, 2014 Discussion TopicsExisting MITR Nuclear Instrumentation & ControlUpgrade to Digital Nuclear Safety SystemFission Chambers & Pre-AmplifiersDescription of DWK 250 ChannelDescription of Scram Logic CircuitSecurity & Cyber Vulnerability EvaluationLicenseAmendmentRequestDocuments&ScheduleLicense Amendment Request -Documents & ScheduleQuestions & CommentsPhase 0 Review Meeting 2 Existing MITR Nuclear I&CTenchannels-Channels#1through#9plusChannel#N-16Channels #1 through #6 are the six fully analog nuclear safety channels to be upgraded to digitalTen channels Channels #1 through #9 plus Channel #N16pggCh. #1 through #3 forshort reactor period scramCh#4thh#6fCh. #4 through #6 forhigh neutron flux level scramCh. #1 & #2 operate on fission hbfdchambers for source range andare switched to ion chambers forpower rangeCh#3operatesonionchamberthatcomesonscalestarting05kW3Phase 0 Review Meeting Ch. #3 operates on ion chamber that comes on scale starting ~0.5 kW Operational Specifications forNuclear Safety System Ch. #1 -6TwooutofthreeperiodandfluxlevelchannelsmustbeoperableTwo out of three period and flux level channels must be operable whenever the reactor is criticalShort period trip at 10 secondsHigh neutron flux level tripat 6.5 MW (80 kW without primary flow)Time from initiation of scramsignalto 80% control rod insertionis < 1 second.Channel tests quarterly, beforeeach startup, and after repair or de-energizing4Quarterly channel calibration on startup checklists (annual per Tech Spec)Phase 0 Review Meeting Instrument Transition fromSource Range to High Power RangePrior to startup, Ch. #1 & 2 are on scale with their fission chambers; Ch. #3 is not on scale~0.5 kW Ch. #3 comes on scale;switch Ch. #1 to ion chamberWhen Ch. #1 on ion chambercomes back on scale,switchCh. #2 to ion chamberBy 2 kW, Ch. #2 on ion chambercomes back on scale, so all threeare now on scale on ion chambersThroughout the startup, Ch. #4 through Ch. #6 are on scale with their ion chambers; perceptible readings appear ~500 kW5Phase 0 Review Meeting Proposed Upgrades for theNuclear Safety SystemRlChl#16Replace Channels #1 -6Wide-range operation so there will be no detector switchingFieldprovenwithreliableapplicationinnuclearreactorsField-proven with reliable application in nuclear reactorsFour channels; each can provide scrams on short reactor period and high neutron flux level (same set points and scram time as previous)Two out of four channels are required to be operable whenever the reactor is criticalChannel test/calibration possible with the reactor operatingOriginal Tech Spec will be mostly unchanged6Phase 0 Review Meeting Proposed Upgrades for theNuclear Safety System7Phase 0 Review Meeting Proposed Upgrade to theNuclear Safety System -Logic Detail 8Phase 0 Review Meeting Fission Chambers and Pre-AmplifiersAllfourfissionchambersareAll four fission chambers are of identical design and build, from Mirion USEachdetectoris107"longEach detector is 10.7 long and 2.6" diameter, with a triaxial integral quartz cable 7feet longEach chamber feeds a pre-amplifier (Mirion TKV 23),

which passes the amplified fission chamber signal to the DWK 250 for processingPre-amp has a built-in pulse 9signal and AC signal test generatorPhase 0 Review Meeting Fission Chamber Detector Placement10Phase 0 Review Meeting DWK 250 Analog & Digital Signal Paths(Image removed for proprietary protection.)11Phase 0 Review Meeting One of Four NewMirion DWK 250 Channels for MITREachchannelprovidesEach channel provides short reactor period scram

& high reactor power scramEachchannelutilizesoneEach channel utilizes one fission chamber for wide-range power operationReactorpowerandperiodReactor power and period calibration and scram checks can be done with the reactor operatingTest signal travels along the detector signal path starting from the fission chamber 12pre-amplifierPhase 0 Review Meeting One of Four NewMirion DWK 250 Channels for MITREach DWK 250 monitor incorporatesthreedifferentincorporates three different microprocessor modules for signal processingEachmicroprocessorexecutesitsEach microprocessor executes its function as set by the firmware permanently programmed into its non-volatile memory EPROMsExecution of firmware is confirmed by continual checksum comparisonMicroprocessors and firmware have field-proven reliable for

>25 years in European nuclear 13industryPhase 0 Review Meeting One of Four NewMirion DWK 250 Channels for MITRThe microprocessors phandle pulse signals and also perform "Campbelling",

allowing wide-range indicationindicationTrip set-points do not driftDetector voltage and ginternal operating voltages monitored for compliance with adjustable tolerancesContinuous Op-code handshaking between the DWK's microprocessorsasanactivecheckof14as an active check of functionalityPhase 0 Review Meeting One of Four NewMirion DWK 250 Channels for MITREihtbi(l)ttEight binary (relay) outputs -DWK uses two for internal fault indication; MITR uses two for scram circuitTwoanalogoutputsTwo analog outputsOne serial communication output (RS232 port)MITRwillusethesefor15Phase 0 Review Meeting MITR will use these for display and recording DWK 250 Functional Diagram(Image removed for proprietary protection.)16Phase 0 Review Meeting DWK 250 Quality StandardsDWK 250s, their firmware, and their TKV 23 pre-amps were designed and manufactured in GermanyQualified by TUV per German nuclear regulatory KTA guidelines 3501, 3505, 3507, and 1401, for type approval tests of safety-related I&C systems in accordance with Category A of IEC 61226 Category A is equivalent to IEEE 323 Classification 1E equipmentfornuclearpowerstationsandtoIEEE344equipment for nuclear power stations, and to IEEE 344 Classification 1E equipment with regards to seismic qualification17Phase 0 Review Meeting MITR Protection System Logic CircuitTwo-out-of-four coincidence logicusedinthisdesignlogic used in this designA single scram output from a DWK 250 will not result in an immediatereactorscramunlessimmediate reactor scram unless a second unit has tripped or faulted.Totalof29inputstotheScramTotal of 29 inputs to the Scram Logic System Scram Logic System has two identicallogiccircuitsinCard1identical logic circuits in Card 1 and Card 2Coincidence logic is applied in thecardstoproduceareactorthe cards to produce a reactor scram18Phase 0 Review Meeting Logic Circuit -concept detailAnycombinationoftripsAny combination of tripsor fault conditionson two DWK 250s will result in a reactor scram19 Logic Circuit -developmentBllidifBoolean logic diagram for two-out-of-four coincidenceVerified by computer-based logicgatesimulatorlogic gate simulatorFPGA device for logic test29inputstologiccircuits29 inputs to logic circuitsTesting board createdGeneration of CAD layout for prototypeprintedcircuitboardprototype printed circuit board20Phase 0 Review Meeting Boolean Diagram -Output ofLogic Gate Simulator21Phase 0 Review Meeting Logic Diagram -Output fromQuartusII22Phase 0 Review Meeting Security & Cyber Vulnerability Evaluation FirmwareonthethreemicroprocessorsforeachDWK250Firmware on the three microprocessors for each DWK 250 cannot be alteredFirmware and its downloading are safeguarded at Mirion GermanyGermanyAdjustable parameters (alarm set points, discriminator threshold, etc.) can be changed from the front keypad only when a key switch is enabled; otherwise the terminal block at the back must be used, as the front RS232 connector will be physically removed once testing phase is completeFinal position of DWK 250s will be in the control room, which is continuously monitored or safeguardedSystemwillnotbeconnectedtoanynetwork23System will not be connected to any networkPhase 0 Review Meeting License Amendment RequestFinal logic circuit design & testing planSAR RevisionAmendment to Technical SpecificationsProjected Schedule24Phase 0 Review Meeting Concluding MaterialQuestions & CommentsContactInfo:Contact Info:Edward S. LauMITNlRtLbtMIT Nuclear Reactor Laboratory138 Albany Street, NW12-122 Cambridge, MA 02139617-253-4211 eslau@mit.edu25Phase 0 Review Meeting