Fission-track assay for fissile nuclides in tissue. Final comprehensive summary report, 1 July 1982-30 June 1985 on Phases 1 and 2

Fundamental techniques for a Fission Track Assay for Fissile Nuclides in Tissue were developed. Accomplishments can be summarized as follows: Pu and U were chemically separated from each other and from bulk contaminants frequently encountered in ashed tissue specimens. The preparation of sample-detector assemblies was standardized and conditions for neutron irradiation, subsequent track etching, and quantification were established. Program-controlled procedures were developed to eliminate erroneous interpretations of fission-track images and to guarantee the statistical validity of the track quantitation. The background due to external contamination with uranium was reduced to acceptable levels. A survey of Pu distributions in livers, kidneys, spleens, and lungs and skeletons of experimental animals was performed. Reproducibility and accuracy of the assay were tested on small beef-liver samples tagged with 1.0 and 0.1 fCi /sup 239/Pu and on dry, /sup 239/Pu-containing liver powder obtained from the National Bureau of Standards. The Pu distribution and average concentration of six livers of humans from Southern Utah and Northern Utah have been determined and the results were compared with those obtained from the same organs by alpha-spectrometric methods. Presently, the lower limit of the /sup 239/Pu quantitation using a reported thermal-neutron fluence of 5 x 10/sup 17/ n/cm/sup 2/more » is approximately 1 fg or less than 10/sup 16/ Ci. Thus, Pu resulting from 1/10,000 of the maximum permissible whole body burden of .00000004 Ci could be quantitated in a 100-mg bone specimen, assuming a uniform skeletal deposit of /sup 239/Pu.« less