ESHQ Radiation Physics Engineering: New Safety System and Instruments Adam Olson Engineer Retreat – Engineering within Fermilab 20 February 2018
New Safety System and Instruments Presentation • Topics for this presentation – The design of a new PLC-based, rack-mounted, ODH safety system – The design of a new radioactivity classification instrument – The design of a new interlocked radiation area monitor instrument 2 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System Project – Interlocks Team • Design a new hybrid system based on existing ODH systems – Combines the advantages of the current rack-mounted ODH system with beneficial features from the current PLC-based ODH system • Advantages of the existing rack-mount system: – Simplified use, lower cost, smaller size and portability • Advantages of the existing PLC system: – More reliable oxygen sensor, industry-standard safety rated components, and computer processing capability 3 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – PureAire Sensor • PureAire sensor chosen for the new system – Zirconium oxide sensor not dependent on barometric pressure – 10 year cell expiration – 4-20mA current loop interface 4 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Helium Sensitivity Error • PureAire sensor is sensitive to helium in the air – Reads higher than normal oxygen in the presence of low levels of helium – this is an unsafe condition • Empirically derived look up table to compensate for an assumed ever-presence of helium – Piecewise linear curve with four inflection points across the measurement range – Thousands of data points can be programmed with a PLC 5 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Helium Compensated Data • Application of the helium compensation curve to the raw data 6 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Block Diagram 7 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Prototype Internal 8 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Readout and Interface Panels 9 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Prototype Front Panel 10 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Oxygen Safety System – Benefits • Benefits – Reduces the number of false alarms under the current rack- mounted system – Reduces maintenance and calibration costs – Cheaper to install than the full PLC ODH system – More portable than the full PLC ODH system – Uses a safety rated PLC – Barometric pressure independent sensors – Helium compensated measurement for unsafe condition 11 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 Project – Instrumentation Team • The humble Geiger counter with some bells and whistles • Replaces the original, 40+ years old wallflowers designed by physicist Bob Shafer • Fulfills instrumentation needs of radiological workers at Fermilab 12 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Prototype Unit 13 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – How it works 14 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Mechanical • Housing modifications – Fit everything in a portable housing that can take abuse in the field – Machining of the plastic housing • 3D printed parts – 3D printer (MakerBot Replicator) custom parts – Precise alignment of GM Tube, check source, and sonar transducers • Custom overlay with integrated push button and transparent window 15 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – 3D Printed Components 16 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Assembled Prototype Internals 17 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Prototype PCB 18 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Software • Embedded system programmed in C – No operating system → creation of Wallflower Board Support Package (BSP): – Modular C units sharing memory, data, interrupt time, and hardware resources – No dynamic memory allocation allowed • Embedded Rad Instrument – Abstraction of the radiation instrument to the application programmer • Makes it easier to build up new instrument configurations without code restructuring – USB communication and the instrument’s serial protocol – Calibration/testing applications vs. the end user application 19 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
Wallflower 4 – Benefits • ALARA-friendly goals: – Reduce user error in measurement and classification of items – (Future) Reduce process duration with statistical analysis (standard error) to complete measurements just-in-time. • Directly measures a standard reference for the radiation intensity with the sonar distance. • Transformable, portable, modular BSP: – New graphics, fonts, peripherals, process pages, scales/units, USB commands and more could be changed to make a completely new instrument with the existing design. – If the Fermilab Rad Worker procedure changes, the instrument could be adapted in software. 20 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor Project – Instrumentation Team 21 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Design Committee • It will replace the Chipmunk and Scarecrow radiation area monitors all over the lab • Fulfills the needs of RSOs to interlock radiation areas • Created a committee for future radiological instruments with stakeholders from ESHQ teams: – Instrumentation – Interlocks – Radiation Safety Officers – Radiation Physics Science team 22 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Instrument Simplification • Quality Factor-less – Exact weighting factors will be determined by the RSO and applied directly in the interlock’s trip setting without any need for configuring the instrument hardware • Uniform dose per pulse in units of 1 µrad to simplify math and instrument configuration – Inspired by the FOX x-ray area monitor with 1µR/pulse 23 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Prototype • Prototype made from a Chipmunk yellow box with new guts 24 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Hardware • Environmentally rugged specs – -30 ° to +50 ° C operating temperature – 93% Relative Humidity at 30 ° C – EMI and ESD protection • Surface mount digitizer board – New Texas Instruments electrometer opAmp – LMP7721 – Active guard ring to minimize leakage – Minimize parasitic effects on layout – No floating components – Sensitivity of 2pC/count working 25 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Digitizer Prototype • Electrometer with active guard ring around its input • Case with gasket, grease seal, and desiccant plugs to keep out moisture 26 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Control Board Prototype 27 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
New Area Monitor – Benefits • Flexible weighting factors • Higher output sensitivity, uniform dose/pulse of 1 µrad compared to Chipmunk. • Lower power draw • Reduces black magic required to build and fix digitizers • Dual power, option to not need electrician work • Smaller physical size • Recycles the Chipmunk ion chambers • Cheaper unit cost • (Future) Expandable IO with the FPGA 28 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
The End • Thank you for your time! 29 Adam Olson | ESHQ RPE: New Safety System and Instruments 2/20/2018
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