Table 5. Detection limits (la) of selected gamma-emitting radionuclides in the Bikini Atoll environment as a function of sample size. pCi/sample - 1000 minutes counting time Sample size (g) 3+ 2 10+ 5 70 + 30 160 + 60 40¢ 60¢9 1Omag 125sh 137¢s5 155ey 207 pj 241 An 10 15 20 30 1.0 1.6 2.4 3.6 1.0 1.8 3 at 4.5 1.2 1.7 2.9 4.6 0.5 0.8 1.2 1.8 0.9 1.4 2.4 4.0 0.8 1.5 2.2 3.2 1.5 2.5 4.0 7.5 After gamma analysis, a number of samples were selected for radiochemical analysis for 90Sr, 137cs, 113mcq, 238,239,240py, 24lam, 210p9, 210Ph, and 210Bi. Activities of these radionuclides were measured using either alpha- spectrometer systems or low-background beta detectors. Measurements of these radionuclides were conducted because some were judged to be of potential Significance for dose assessments and others were analyzed to meet specific programmatic objectives. The !3/Cs was often radiochemically separated from muscle tissue and analyzed RRR a spectrometry, which, to confirm the measurements made by gamma in turn, provided a useful laboratory calibration for quality control. Quality of data has always been an important aspect of our analytical measurements. As a standard practice, 5 to 10% of our time is devoted to quality-assurance work in all projects involving analytical measurements. This quality-assurance work includes e Analysis of background samples and blanks. e Instrument calibration. ° Duplicate sampling and analysis. ° National and international interlaboratory standardization. ° Replicate measurements. . Analysis and calibration traceable to National Bureau of Standards samples. e 9000564 Appropriate statistical analysis of the results. 10