  New data are reported for polyvinylidene fluoride (PVDF), polyphenylene
sulfide (PPS), and two forms of polyetherimide (PEI, branded ULTEM 1010 and
9085). Data for starting filaments and both simple and complex printed parts
are reported. PVDF filaments and simple printed beads, were found to have
values of approximately 30 and 50 ppt for Th-232 and U-238, respectively, while
a more complex spring clip part had slightly elevated Th-232 levels of 65 ppt,
with U-238 remaining at 50 ppt. PPS filament was found to have concentrations
of 270 and 710 ppt for Th-232 and U-238, respectively, and were not chosen to
be printed as those levels were already higher than other material options.
ULTEM 1010 filaments and printed complex spring clip parts were found to have
concentrations of around 5 and 7 ppt for Th-232 and U-238, respectively,
illustrating no significant contamination from the printing process. ULTEM 9085
filaments were found to have concentrations of around 9 and 5 ppt for Th-232
and U-238, respectively, while the printed complex spring clip part was found
to have slightly elevated concentrations of 25 and 7 ppt for Th-232 and U-238,
respectively. These results were all obtained using a novel dry ashing method
in crucibles constructed of ultralow background electroformed copper or, when
applicable, microwave-assisted wet ashing digestion. Samples and process blanks
were spiked with Th-229 and U-233 as internal standards prior to dry/wet ashing
and determinations were made by inductively coupled plasma mass spectrometry
(ICP-MS). In order to maintain high radiopurity levels, pre-cleaning the
filaments before printing and post-cleaning the parts is recommended, although
the printing process itself has shown to contribute very minute amounts of
radiocontaminants.

Instrumentation and Detectors;High Energy Physics - Experiment;Nuclear Experiment