Fallout Monitoring and Documentation 1. Deposition The two important features of deposition are the total accumulated fallout and the fallout rate. The measurement of fallout rate requires collection over relatively short periods, usually on the order of one month, and radiochemical measurement for sr9°, The stainless steel open vessel or pot,when exposed continuously, collects both dry fallout and material carried down by precipitation. The material carried down by individual rainfalls is also monitored to obtain meteorological information as to the probable atmospheric souroe of fallout. Such short term collections may also be analyzed for sharter-lived isotopes to estimate the approximate age of the radioactive debris. The radiochemical analysis of soils allows direct measurement of fallout accumulated since the start of testing.