RADIOCHEMICAL FRACTIONATION CHARACTERISTICS 11: tioned represent the predominant peaks in the spectra obtained. Figure 2 indicates a typical gamma-spectrometer scan observed over a twoyear-period. The background radiation is the lowest line. The peaks o interest are singled out on the figure. RADIOCHEMICAL STUDIES Calculations of the counting-rate yield at zero time for a particle representing 10° fissions indicated that measurable activities would be obtained for the nuclides of interest if nofractionation is assumed (see Table 1). However, fractionation effects in single particles caused wide Table 1— THEORETICAL RADIOCHEMICAL SENSITIVITY FOR A PARTICLE OF 108 FISSIONS (Basis: Counting Rate at Zero Time for 100% Chemical Yield) Nuclide Counts/min 83Sr 30Sr O7r 2r 23 0.1 10 1000 IMO 562 Ml ag hog 13Ru ICs M0Ra i1ce 1440 @ Sly U6ry 0.2 0.05 Zero abs, R=1 R= 0.09 R= 94 24 7.4 25 0.06 40 0.004 44 200 8%Cu 0.06 203 Ph 21Th 0.015 900 a3Tyy 239Nip 2407] 238py 239 Py/Jt 0.23 690 2880 2880 0.00005 *N = atoms, f = fissions. R=1 R=1 R=1 MTN TBe 24Na Cu 187W R=1 R=1 R=1 110 abs, R=1 0.5 2 2 10 Ry 136Cs Remarks 0.0009 Zero abs, R= 1 R= Zero abs, R=1 zero abs, R= 1 R=1 74 abs, R=1 R=1 N/f* = 100 x 1075 N/f = 100 x 1075 N/f = 1000 x 107° N/f = 1x 1075 N/f=1x 107% N/f=1x 1075 N/f = 100 x 1073 N/f = 0.3 N/f = 0.3 N/f= 0.1 N/f = 10 x 1075 N/f = 0.5 tJ = [atoms 738Pu/atoms *4°Pu/(atoms *8Pu/atoms *4°Pu) + 3.7).