Health Physics Pergamon Press 1978. Vol. 34(March), pp. 209-217. Printed in Great Britain 407958 ANALYSIS OF ALPHA EMITTERS IN THE CORAL, FAVITES VIRENS, FROM BIKINI LAGOON BY SOLID-STATE TRACK DETECTION YITZHAK LEVY, DONALD S. MILLER and GERALD M. FRIEDMAN Department of Geology, Rensselaer Polytechnic Institute Troy, NY 12181 and VICTOR E. NOSHKIN Lawrence Livermore Laboratory, Livermore, CA 94550 (Received 8 November 1976; accepted 10 July 1977) Abstract—A quantitative method for the non-destructive analysis of alpha emitters in CaCO, matrices by solid-state track detection (cellulose nitrate) was developed. 0.4 pCi/g in an area of 4mm7?can be measured routinely; smaller concentrations can be determined but with a lower resolution. Calibration methods used were (a) a Pu source of 0.15 wCi in conjunction with polycarbonate and CaCO, absorbers of different thickness (2-30 um) and (b) a powdered coral sample from Enewetak Atoll which had been tadiochemically analyzed for plutonium radionuclides, **'Am and other long-lived fission and activation products. Slabs of a coral, Favites 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) are found in small discrete spots. Thin sections cut parallel to the direction of coral growth give different patterns of distributions. No such “hot spots” are evident in any post-test year growth sections although plutonium and other long lived fission and activation products were measured in these sections by radiochemical techniques. INTRODUCTION Many applications of solid-state track detectors have been made in several fields of engineering and science (F175). Alpha-particle detection using cellulose nitrate as the solidstate track detector has been developed to the stage whereby distribution of alpha emitters at very low concentration levels can be determined. The efficiency for the solid-state alpha track detector (Kodak LR-115, Type I) was determined using a very thin 7’Pu cali- brated source in conjunction with alpha energy degraders of polycarbonate and calcium carbonate films and a powdered coral sample of known plutonium and americium activities. A coral, Favites virens, collected alive from Bikint lagoon in 1972 was sectioned for analysis. Relatively high radionuclide levels, including plutonium radionuclides and “'Am, were detected in the coral growth sections corresponding to the nuclear testing years of 1954, 1956 and 1958 (No75). Since it has been demonstrated (Ba74) that coral skeletons are excellent samplers for suspended particulate material in the water column it was of interest to determine whether the radionuclides detected in the coral-growth increments were taken up as dissolved species or were taken up, in part, through particulate incorporation. Through the application of the solid-state alpha detector to slabs (1 cm thick) and thin 209 HP Vol. 34 No 3—A R