Analysis of Alpha Emitters in the Coral, Favites Virens, from Bikini Lagoon by Solid-state Track Detection

Abstract

A quantitative method for the non-destructive analysis of .alpha. emitters in CaCO3 matrices by solid-state track detection (cellulose nitrate) was developed. A level of 0.4 pCi/g in an area of 4 mm2 can be measured routinely; smaller concentrations can be determined but with a lower resolution. Calibration methods used were a Pu source of 0.15 .mu.Ci in conjunction with polycarbonate and CaCO3 absorbers of different thickness (2-30 .mu.m) and a powdered coral sample from Enewetak Atoll which was radiochemically analyzed for Pu radionuclides, 241Am and other long-lived fission and activation products. Slabs of a coral, F. virens, from Bikini lagoon were analyzed. A quantity of the .alpha. emitters detected in regions of the coral identified with growth during the years of nuclear testing (1954, 1956 and 1959) were found in small discrete spots. Thin sections cut parallel to the direction of coral growth gave different patterns of distributions. No such hot spots were evident in any post-test year growth sections although Pu and other long-lived fission and activation products were measured in these sections by radiochemical techniques.