Monitored Analog Safety System - IEEE-SA - Working …grouper.ieee.org/groups/npec/N13-02_NPEC...
Transcript of Monitored Analog Safety System - IEEE-SA - Working …grouper.ieee.org/groups/npec/N13-02_NPEC...
Monitored Analog Safety System
Bob QueenanI&C Manager, Scientech
a Curtiss Wright Flow Control company
Brief Background• I&C Division Manager for Scientech, a CWFC company• I&C Manager at DC Cook during restart• I&C Supervisor at Catawba• Consultant out of Atlanta (Impell, ATESI, Enercon,
Pacific Nuclear)• Protection System Supervisor at B&W• Sideways trip into deep sea mining I&C• Los Angles Class Submarine design engineer at
Newport News
• Senior Member of ISA– Chair of ISA SP‐67 on Nuclear Standards– Former Chair of SP‐67.04, Nuclear Setpoints
• Member of IEEE – SC‐2 (Qualification), SC‐2.01 (EQ), SC 2.05 (Seismic)
• Member of ANS
2
• Bachelor of Science / E.E. from Case Western Reserve University
• Masters in Nuclear Physics from Lynchburg College
• Technical Nuclear Certification ‐McGuire
Why Digital?
• Everything is digital now• Great HMI – limited only by imagination• Fast response time• Almost unlimited flexibility • Wide access to data• Components are easy to replace
Why Analog?
• Protection systems don’t need digital– They have simple functions– They don’t change often– They have limited HMI
• Analog lasts longer than Digital• Safety software gets intense NRC review
– Interim Staff Guidance– Dozens of new IEEE standards– The ever‐changing cyber security threat
Time to Think
WANTDIAGNOSTICS
NOSOFTWARE
NEED ACCESS TO DATA
WANTONLINE
MONITORING
WORRIEDABOUTCYBER
• Use analog circuitry to perform the safety function
• Isolate the data …
• … to a non‐safety multiplexer …
• … and to a non‐safety computer.
• Send the data and results to the plant computer / data network.
SAFETYCIRCUITS
PLANTCOMPUTER
CR3 ICCMS
The Inadequate Core Cooling Mitigation System• After a reactor trip
– On loss of subcooling, trip the RC pumps to avoid pumping froth.
– On loss of subcooling, raise the OTSG level to promote natural circulation.
– On loss of subcooling AND insufficient HPI flow, initiate fast cooldown.
ICCMS Configuration
SENSORCHANNEL 1
SENSORCHANNEL 2
SENSORCHANNEL 3
ACTUATION TRAIN A
ACTUATION TRAIN B
POST ACCIDENT MONITORING CHANNEL 1
POST ACCIDENT MONITORING CHANNEL 2
MULTIPLEXER MULTIPLEXER MULTIPLEXER
ON LINEMONITOR
PLANTCOMPUTER
Design Requirements
• Full IEEE‐279/603 Protection System– Mild Environment Qual – IEEE‐323– Testability – IEEE‐338 / GDC– Single Failure – IEEE‐379 / RG 1.53– Seismic Qual – IEEE‐344 / RG 1.100– Separation – IEEE‐384 / RG 1.75– EMI/RFI – TR‐102323 / RG 1.180– Software Qual per ISGs – not applicable– Cyber Security precautions – not applicable
Design Goals
1. Incorporate lessons learned from 30 years of using analog protection systems
2. Maximize use of commercial parts thru CGD3. Protect circuitry from EMI/RFI4. KISS ‐most systems work best if they are kept simple rather
than made complex
1. Lessons Learned
• No card edge connectors !!• Build in test switches, test points, and simulated inputs.• Qualify with the doors open.• Provide utility power outlets in rear of cabinet.• Minimize custom hardware & accessories• Adjustable filters on all analog inputs• Redundant power supplies wired for hot swap• Time delays set by thumbwheel switches to the nearest second
2. Commercial Parts
• Hoffman seismic cabinet, standard 19” racks, standard EURO modules
• DIN rail power supplies, media converters, relays, fuses, and terminal blocks
• Commercial multiplexers with standard connectors• Industrial PC running Windows
3. Protect from EMI/RFI
• Sensitive electronics in Faraday cage with PI filters on all inputs and outputs
• Line filters on all AC power inputs• DC power supplies outside the
cage• Field wiring confined to rear of
cabinet• All cabinet‐to‐cabinet signals over
fiber optics
4. KISS
• Used simple building blocks –summers, alarms, function generators, square root extractors, auctioneers
• Combined them into simple loops• Used Analog & Digital input modules• Used Analog & Digital output modules
Some Details
• PC boards are multi‐layer, with ground planes top and bottom to increase EMI/RFI resistance. Use of modern components results in a clean board with very little hand wiring compared to older modules.
Some Details
• Spec200 2ARPS‐A6– Input = 115 Vac @ 60 Hz– Output = 15 Vdc @ 5 A– 19” x 13” x 9”– 53 lbs
• Phoenix Contact 2938853– Input = 115 Vac @ 60 Hz– Output = + 24 Vdc @ 5A– 5” x 5” x 2”– 2.2 lbs
Some Details
• Terminal blocks– Allow direct connection of test equipment
– Ring lugs, but captive screws ‐ no loose hardware in cabinet
– Built in sliding link to disconnect – no lifted leads
Some Details
• Improved Accuracy– Most analog legacy systems have 0.25% or 0.50% accurate modules, and 1‐2% accurate cabinets.
– Most ICCMS modules have accuracies of: Ref = 0.05%TE = 0.05% over a 40F to 160F rangePSE = 0.05% over the full range of the power supplyDRIFT = 0.05% over 120 daysTDU = SRSS( 0.05, 0.05, 0.05, 0.05) = 0.10% span
– Overall cabinet trip accuracy was 0.64% span
Some Details
• Qualification – OEM equipment– Design, Buy, Build, Test– Allows custom functionality
• Commercial Grade Dedication – OTC equipment– Buy a few extra, Test– Have to accept what’s on the market
• CGD was less expensive, faster, more predictable
Summary
• Analog works for simple systems, like RPS, ESFAS, EDG Sequencers, TSAT systems, and the like
• Careful design allows online monitoring & full access to all data by non‐safety computer systems
• Avoiding the licensing of safety‐related software saves significant time and money