FALLOUT PROGRAM QUARTERLY SUMMARY REPORT

II IIIIIIIIIIIIIIIIFALLOUT PROGRAMQuarterly Summary ReportJanuary I, 1961Part I - Data From the HASL Fallout Program1. Monthly Fallout Deposition CollectionsMonthly fallout deposition rates are estimated by HASL frommeasurements of the radioactivity in precipitation samples collected at 40monitoring sites in the United States and 83 sites in foreign countries.Additional data are obtained from samples collected at four U. S. WeatherBureau ships stationed at known locations in the North Atlantic Ocean. Themonitoring sites are indicated in Figure 1. Monthly precipitationcollections are made using either stainless steel pots with exposed areasof 0.82 square feet, or funnels with exposed areas of 0.85 square feet towhich are attached ion exchange columns. The collections on board the shipsat sea are made in rain gauges with exposed areas of 0.56 square feet.1.1 HASL AnalysesAll samples are obtained at the individual sites by U. S.Weather Bureau personnel or other scientists who have volunteered to cooperate in this program. Except for HASL contractor collections, thesamples are forwarded to the Health and Safety Laboratory for radiochemicalanalyses. In late 1958 and 1959 these samples were analyzed forstrontium-89, tungsten-185 and strontium-90, but since the strontium-89and tungsten-185 levels have dropped to such low levels, analyses for thesenuclides have been discontinued in 1960.1.2 HASL Contractor AnalysesAnalyses of samples collected at Louisville, Kentucky; Houston,Texas; Westwood, New Jersey; Pittsburgh, Pennsylvania; and Richmond,California are made by private contractor laboratories. At the latterthree sites in addition to the monthly samples, individual rainfallcollections are made- Monthly collections made by contractor laboratoriesare made in duplicate and analyzed for total beta activity, strontium-89,tungsten-185, plutonium-239,, cerium-144 and strontium-90. Samplescollected in Pittsburgh are analyzed for ruthenium-106 in addition to theother radionuclides. Data on monthly precipitation collections obtainedby the contractors are included together with the HASL results in Table laahd Ib, pages 8 to 92.Individual precipitation collections commence immediately aftera rainfall and terminate either after the next rainfall or after a week- 2 -