Calculations were performed which indicate that thermal flux increases of a factor of 20 should be possible through the optimal use of fissile material regions surrounding 252Cf sources. For demonstration purposes, a subcritical system was assembled and used for trace element determination in marine life, terrestrial biota, and mineral specimens. This multiplying assembly consisted of PuO2 admixed with polystyrene and reflected with Plexiglas. Source neutrons were provided by a 200µg 252Cf source. A neutron flux amplification of about fivefold was achieved at the 252Cf source, while an amplification of some 40-fold was obtained 16 cm from the source where the majority of source exposures would be made.