Determination of americium-241 in sediments by gamma spectroscopy

Abstract

A radiochemical method is given for the determination of Am-241 from the global fallout in sediments. The concept of a concentration step to separate Am-241 from the bulk of the sample (1-2 kg wet) by coprecipitation followed by low energy gamma spectroscopy was investigated. A series of experiments with tracer added was performed to measure the recovery of americium by coprecipitation. Also, a number of real samples without tracer were examined and the conditions for the optimum separation are given. The applied gamma method and the conventional, accurate, but tedious, aplha technique via 243Am, which is usually applied for the determination of Am-241, agreed mostly within 10 %.

Ispitana je mogućnost prekoncentrisanja Am-241 iz velike mase sedimenta (1-2 kg) pre njegovog određivanja gama spektroskopijom. Separacija je vršena da bi se sav Am-241 izdvojio na pogodnom nosaču, odnosno da bi se dostigla granica osetljivosti instrumenta, jer je Am prisutan u sedimentima u izuzetno malim količinama (0,01-0,5 Bq/kg). Serijom eksperimenata sa obeleživačem određen je stepen separacije dobijen koprecipitacijom. Primena metode na uzorke sedimenata sa različitim sadržajem americijuma pokazala je da je slaganje rezultata dobijenih ovom metodom sa rezultatima dobijenim alfa spektroskopijom bilo 10%.