NEW RADIOCHEMICAL PROCEDURES FOR ENVIRONMENTAL ACTINIDE MEASUREMENTS AND DATA QUALITY-CONTROL

Suitable separation techniques were prepared for actinide, Sr-90 and R a-226 determinations in environmental and industrial samples. Extracti on chromatography with tri-n-octylphosphine oxide (TOPO) and di(2-ethy lhexyl) phosphoric acid (HDEHP) solutions was, used. In some cases, a powder of Microthene (Microporous polyethylene) supporting solid TOPO was prepared thus obtaining a material showing better storing and colu mn preparation features. Uranium and Ra-226 were determined in phospho rites, phosphoric acid and phosphogypsum. Uranium, thorium and Ra-226 were also measured in the low specific activity scales of hydrocarbon production equipment: Ra-226 was found to concentrate in some parts of the plant so causing a radiation protection problem. Plutonium and Sr -90 were measured either in some Mediterranean Sea samples or in envir onmental samples collected in Antarctica. Some interesting sea sedimen t profiles were also obtained. All the chemical methods were verified by: a) adding some yield tracers (U-232, Th-228, Pu-242); b) analyzing some certified samples supplied by IAEA and NIST; c) participating in some international intercomparison runs; d) using, when possible, bot h an analytical and a radiometric method and e) following the radioact ivity decay or growth (Y-90 and Ra-226).