radionuclides within the NTS, and to assist in providing guidance for the possible cleanup of plutonium-contaminated areas. Progress in this project has resulted primarily from experiments carried out at the intensive study location at the GMX site in Area 5. In addition, less elaborate measurements have been conducted at several additional areas of plutonium contamination. Off-site experi- ments concerning parameterization of dust fluxes and mass loadings have been conducted near Plains, Texas. Interim models developed from these studies have been utilized in radiological assessment of the reoccupation of Enewetak Atoll and in the environmental assessment of liquid-metal fast breeder reactor technology. PAST ACCOMPLISHMENTS Nine reports (see References 1 through 9, this report) have been published or submitted for publication since July 1, 1974. These publications cover in detail the experimental measurement programs, results of measurements, and the data analysis including model development which has resulted. Additional data have also been collected which are not covered by these publications and include measurements of the concentration of the plutonium in air at other NTS locations in addition to the GMX. some highlights of these past accomplishements are listed below: 1. Concentration of resuspended plutonium in air has been measured over short time periods of consistent meteorology with the use of ultrahigh-volume air samplers (1,500 m>/fhr) . Simultaneous measurements of wind speed and temperature profiles, in addition to other meteorological variables, have provided the first welldocumented set of resuspension measurements made over short time periods. Important meteorological parameters, friction velocity (u*), surface roughness length (Zz), and Richardson number (Ri) *The resuspension factor is the concentration in air divided by the surface deposition and has units of mt, 93