partition. The larger work area contained hoods, grinders, furnaces and tables and was not air-conditioned due to the large air flow requirements of the hoods. The smaller section was set up with air-conditioning to provide humidity and temperature control for the electronic instruments and sensitive balances. The Sample Preparation Laboratory is shown in Figure 4-2, The work tables, hoods, and related equipment in the large work area were arranged for maximum effective use during production. A large sample logging table was used to check the field samples for proper identification and to log them into record books. Two other tables were used for sample processing and storage. The majority of space in this section was occupied by four fume hoods. One hood (70 x 36-inch) was installed to house two convection drying ovens used to dry the soil samples. The ovens were placed on an Equipto metal bench and had maximum temperature capabilities of 200°C. A second hood (84 x 48-inch) covered a work area for three ball mills and a small coral grinder used to pulverize dried soil samples. The hood was surrounded by a plastic enclosure and curtain shroud for noise abatement and air flow control A third hood (88 x 48-inch) contained two high temperature muffle furnaces and wasset up on a heavy duty steel support table. Firebricks lined the table and back wall for heat protection. Each furnace had temperature capabilities of 700°C and was used to burn organic material from the soil samples. A small planchet drying oven was placed on top of the muffle furnace and inside the hood. This oven was a sheet metal box enclosure that used infrared lamps to dry air filter papers and plancheted samples. The fourth hood was a standard (59 x 29-inch) Labeonco laboratory hood used to handle dry sample material and to remove contaminated balls from the milling cans. It had a higher air flow rate than the other hoods and was principally used to transfer materials and contain soil particulates within the hood. The air-conditioned section of the laboratory had a balance table, gross alpha and beta counters, a gamma screening probe, work desk and shelf storage. The balance table was decoupled from the trailer body by installing the table legs through holes cut in the floor and setting it directly on the concrete pad underlying the trailer. weights. Two laboratory balances were used for measuring sample A Metler analytical balance, sensitive to 0.1 mg, was used to measure aliquots for wet chemistry analyses. A Metler top loader balance, sensitive to 0.1 g, measured the total bulk weight of wet and dry samples and petri dish aliquots for the counting laboratory. The screening probe used was an Eberline Model RD-21 (FIDLER) which detected gross amounts of 241 4m gamma activity in unopened sample cans. The probe functioned to sereen out high activity samples (greater than 60 pCi/g) that might have contaminated the laboratory. The FIDLER was eneased in a two-inch lead shield with an open top, set with the sensitive area up and covered with a 0.125-inch plastic sheet for ean support and dust protection. A field alpha scintillation detector (AC-3) was set up and calibrated to detect gross alpha particles in the soil samples, and a thin window beta detector (HP-210) was used for gross beta counting. All three counting instruments used the standard Eberline scaler-timer model PRS-1 or MS-2 for electronic readouts. Both sealer-timer models were field portable and provided single-channel Pulse Height Analyzer (PHA) capability. Several safety-monitoring instruments were installed throughout the Sample Preparation Laboratory to check air quality control and insure personnel protection. All fume hoods were exhausted through HEPA filters to eliminate the possibility of air contamination on Enewetak Island from the soil samples being processed. The HEPA filter units required changing only once, about halfway through the project, due to dust loading. drop across the filter boxes. Manometers were placed in the work areas to indicate pressure Two air samplers (RAS-1) were used to monitor air particulate concentrations inside the trailer; one sample head was placed in the grinding hood and the other above the balance table. Dust respirators and glove protection were required while working at the Labeonco hood. Dust respirators and ear protection were required while working in the grinding hood. The decontamination facility was located in the rear of the trailer and included a double sink and bench area which provided hot water for cleaning hands, equipment, and milling balls. A solution of Dekasol in a five gallon open-top container was used to decontaminate the mill balls for reuse. Water was drained into the RADLAB complex acid neutralizing tank for processing. Both air quality and contamination control were integral in laboratory procedures to insure personnel safety. Detailed soil sample procedures are discussed in Section 4.3.2. 109