[en] The purpose of this project is to identify, develop, and communicate statistical methodology for environmental actinide studies. Significant accomplishments for FY 1981 included continued publication of TRAN-STAT (a periodical specializing in the statistical aspects of environmental contaminant studies), continued work on our computer simulation study for evaluating ratios, and review of statistical methodology applicable to environmental radionuclides. Related work for the DOE Division Office of Operational Safety included writing the statistical portion of a decommissioning and decontamination guide, expanding our expertise in Kriging and other spatial pattern statistical methodology applicable to the evaluation of potential environmental hazards, continuing statistical support for the Nevada Applied Ecology Group (NAEG), and providing statistical assistance to PNL's environmental radiological monitoring effort