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Open Access Publications from the University of California

Neutron Tomography and Space


The University of California/Davis McClellan Nuclear Radiation Center (UCD/MNRC) was originally constructed by the U.S. Air Force as a nondestructive testing tool to detect moisture and corrosion in large honeycomb filled structures of aircrafts. The MNRC was transferred to UCD in February of 2000 as part of the Base Realignment and Closure (BRAC) process of McClellan Air Force Base. UCD MNRC has a sound base of research and industrial partnerships. Jet Propulsion Laboratory, Pasadena, CA. approached UCD MNRC with the need to image the condition of brushes contained in motors used in their space related projects. JPL explained that they were unable to see what they needed to see with X-rays. They wanted to know if we could see the carbon brushes in these motors. Using their samples, we initially performed two computed radiography (CR) shots 90 degrees apart through the diameter. Furthermore, another shot along the rotational axis was taken. The brushes could not be seen in the shot along the axis. The exposures through the diameter showed an inconsistency between the two motors’ brushes. We then performed neutron computed tomography (CT) on both motors with one degree projection. Reconstruction clearly showed that the motor with the inconsistent shape brushes had the brushes installed incorrectly. There is a significant difference in both time and cost between CR and CT of the motors. CR took about 30 minutes from beginning of the set up to the complete evaluation, while CT took about five hours to finish. UCD/MNRC was not completely satisfied with just saying that there is an inconsistency between the two motors. Through working outside the envelope, a complete picture of the brushes condition was seen with CT in about 30 minutes.

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