Upgraded Helium Refrigerator 

Ryan Fangmeyer
 Conversion to Low Enriched Uranium (LEU) 

 Replacing existing hydrogen cold source with 

deuterium cold source

 New cold source has increased heat load and 

requires upgraded 7kW helium refrigerator

 New refrigerator received from EDEN Cryogenics 

uncompleted

◦ NCNR will complete and start up the refrigerator

Background

2
 Maintaining standards of the NCNR

 Vital to the mission of the NCNR 

 Improving the quality of the cold neutrons supplied 

to the researchers 

Importance

3
 Existing hydrogen cold 

source is being replaced 

with more efficient 

deuterium cold source 

 The deuterium cold source 

will compensate for the loss 

in flux

 The entirety of the system 

is being upgraded

Creation of New Cold Source

4
 Helium refrigerant

 Pressure drop turbine allows 

for greater temperature 

drop 

 Must be enclosed in vacuum

◦ (10-6 Torr)

 Supplies cold helium to the 

condenser which condenses 

the deuterium gas

Helium Refrigerator Background

5
 Programming

◦ Programmable Logic Controller 

 Human Machine Interfaces

◦ Display screens, Alarm, and Bypass screens

 Electrical

◦ Wiring, Diagrams, Instrumentation, Air Actuated Control 

Valves

 Mechanical

◦ Turbomolecular Pump

Project Summary 

6
 Ladder logic software

 Inputs vary from 4-20mA, 0-10V, or 1-5V which are 

converted to counts

 Counts are used to create engineering units

Programming & PLC

7
 Visual representations of 

instruments and systems 

for the reactor operators 

and engineers

 Uses memory variables 

called tags to interact with 

the PLC memory

 Compressor Room/Alarm 

screen/Bypass screen

Human Machine Interfaces

8
9
 Begins with creation of CAD 

model of unit

 High Resolution Print to .tiff 

file 

 Conversion to Factory Talk 

wallpaper

 Creation of tags for each 

instrument

 Placement of display 

components for data values

Creation of Display Screens

10
 Wiring of several controls, actuators, transmitters, 

and PLC connections

 Wiring diagrams kept up to date

 Determining the installation of specific instruments

◦ (research/contacting people/verifying wiring)

Electrical & Diagramming

11
12
 Pressure testing of 

transducers, solving 

problem with continuity

 Must determine varied 

input the PLC will read 

based on pressure

13

Electrical & Testing
 Air Actuated Control Valves

◦ Calibration, troubleshooting, 

programming of limit switches

◦ Digital limit switches or 

mechanical limit Switches

◦ High or low digital readings

Electrical & Troubleshooting

14
 Turbomolecular pump

◦ Conduit created and 

installed

◦ Terminal box created, 

pinned, then wired 

◦ Create PLC interface

Mechanical Installations

15
 Refrigerator is closer to operation

 Turbine instrumentation installation completed

 Vacuum system is now operational

 Control valves are now operating properly

 HMI display more comprehensive

Conclusions

16
 Compressors operational 

 Flowing helium, completing cold box, cooling 

helium

 Replacing the operating refrigerator

 Expected to be commissioned in 2017

Future Work

17
Michael Middleton

Dennis Nester

Dr. Julie Borchers

National Science Foundation - CHRNS

Acknowledgements 

18

Bryan Eyers

Sean Mullendore

Dr. Joseph Dura