Obtaining of 188 W sodium wolframate (Na2 188WO4) using WO3 and W metallic (natural and enriched in 186 W)

This paper presents an obtaining method of Na2188 WO4 by irradiation with thermal neutrons in the Nuclear Reactor TRIGA SSR-14 MW of the Research Institute Pitesti, using as raw material WO3 and W metallic (natural and enriched in 186 W -98%). Na2188 WO4 is an acceptable chemical form for obtaining Na 188 Re O4 (sodium perrhenate). 188 Re obtained is carrier free. Two targets were prepared and irradiated. The first target was natural WO3 and the second, was 98% enriched in 186 W metallic W target. 188 W is obtained as a result of the following nuclear reactions: 186 W(n,γ)187 W (n,γ)188 W. After irradiation and cooling (21 days) the targets were chemically processed. From Na 188 WO4 obtained, we have separated Na 188 Re O4 by using a preliminary MEK extraction, following an elution on an acid alumina (Al2O3) column. The Na 188 ReO4 separated was sterilized by filtering through a 22 μm Millipore filter. We have determined for final product the following physico-chemical parameters: pH value, radiochemical and radionuclidic purity, specific activity, sterility, pyrogenity. All parameters were very good except specific activity, because the bad parameters of irradiation and a very long (21 days) cooling time: pH-6; radiochemical and radionuclidic purity >99%; specific activity for 188 Re - 8,9 MBq/g W for the first target - WO3 (after 21 days of cooling) and 74 MBq/g W for second target - W (98% enriched in 186 W) (after 21 days of cooling), respectively; the product were sterile and apyrogenic. (authors)