ML14078A636
| 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 | |
| Shared Package | |
| ML14078A659 | List: |
| References | |
| TAC MF3106 | |
| Download: ML14078A636 (25) | |
Text
MITResearchReactor MIT Research ReactorEdward S. LauAssistant Director of Reactor OperationsMIT Nuclear Reactor Laboratory Phase 0 Review of MITR ApproachtoaDigitalI&CUpgrade to a Digital I&C UpgradeMarch62014 March 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 u pgraded to di g italTen channels Channels #1 through #9 plus Channel #N 16pggCh. #1 through #3 for short reactor period scramCh#4thh#6 fCh. #4 th roug h #6 f o r high neutron flux level scramCh. #1 & #2 operate on fission hbf d c h am b ers f or source range an d are switched to ion chambers forpower rangeCh#3operatesonionchamberthatcomesonscalestarting05kW 3Phase 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 trip at 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-energizing 4Quarterly channel calibration on startup checklists (annual per Tech Spec)Phase 0 Review Meeting Instrument Transition from Source 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 chamber comes back on scale,switchCh. #2 to ion chamberBy 2 kW, Ch. #2 on ion chamber comes back on scale, so all three are now on scale on ion chambersThroughout the startup, Ch. #4 through Ch. #6 are on scale with their ion chambers; perceptible readings appear ~500 kW 5Phase 0 Review Meeting Proposed Upgrades for the Nuclear Safety SystemRlChl#1 6R ep l ace Ch anne l s #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 unchanged 6Phase 0 Review Meeting Proposed Upgrades for the Nuclear Safety System 7Phase 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 Placement 10Phase 0 Review Meeting DWK 250 Analog & Digital Signal Paths (Image removed for proprietary protection.)
11Phase 0 Review Meeting One of Four New Mirion 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 12 pre-amplifie rPhase 0 Review Meeting One of Four New Mirion DWK 250 Channels for MITREach DWK 250 monitor incorporatesthreedifferent incorporates 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 13 industryPhase 0 Review Meeting One of Four New Mirion DWK 250 Channels for MITRThe micro p rocessors phandle pulse signals and also perform "Campbelling",
allowing wide-range indication indicationTrip set-points do not driftDetector volta g e and ginternal operating voltages monitored for compliance
with adjustable tolerancesContinuous Op-code handshaking between the DWK's microprocessorsasanactivecheckof 14 as an active check of functionalityPhase 0 Review Meeting One of Four New Mirion DWK 250 Channels for MITREihtbi(l)ttEi g ht bi nary (re l ay) ou t pu t s -DWK uses two for internal fault indication; MITR uses
two for scram circuitTwoanalogoutputsTwo analog outputsOne serial communication output (RS232 port)MITRwillusethesefor 15Phase 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 equipmentfornuclearpowerstationsandtoIEEE344 equipment for nuclear power stations , and to IEEE 344 Classification 1E equipment with regards to seismic
qualification 17Phase 0 Review Meeting MITR Protection System Logic CircuitTwo-out-of-four coincidence logicusedinthisdesign logic used in this designA single scram output from a DWK 250 will not result in an immediatereactorscramunless immediate reactor scram unless a second unit has tripped or
faulted.Totalof29inputstotheScramTotal of 29 inputs to the Scram Logic System Scram Logic System has two identicallogic circuitsinCard1 identical logic circuits in Card 1 and Card 2Coincidence logic is applied in thecardstoproduceareactor the cards to produce a reactor scram 18Phase 0 Review Meeting Logic Circuit -concept detailAnycombinationoftripsAny combination of trips or fault conditionson two DWK 250s will
result in a reactor scram19 Logic Circuit -developmentBllidifB oo l ean l og i c di agram f or two-out-of-four coincidenceVerified by computer-based logicgatesimulator logic gate simulatorFPGA device for logic test29inputstologiccircuits29 inputs to logic circuitsTesting board createdGeneration of CAD layout for prototypeprintedcircuitboard prototype printed circuit board 20Phase 0 Review Meeting Boolean Diagram -Output of Logic Gate Simulator 21Phase 0 Review Meeting Logic Diagram -Output fromQuartusII 22Phase 0 Review Meeting Security & Cyber Vulnerability Evaluation FirmwareonthethreemicroprocessorsforeachDWK250 Firmware on the three microprocessors for each DWK 250 cannot be alteredFirmware and its downloading are safeguarded at Mirion Germany GermanyAdjustable 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 safeguardedSystemwillnotbeconnectedtoanynetwork 23System will not be connected to any networkPhase 0 Review Meeting License Amendment RequestFinal logic circuit design & testing planSAR RevisionAmendment to Technical SpecificationsProjected Schedule 24Phase 0 Review Meeting Concluding MaterialQuestions & CommentsContactInfo:Contact Info:Edward S. LauMITNlRtLbt MIT N uc l ear R eac t or L a b ora t ory138 Albany Street, NW12-122 Cambridge, MA 02139 617-253-4211
eslau@mit.edu 25Phase 0 Review Meeting