Evaluated delayed neutron precursor data

Based on energetics, approx.270 fission products should be delayed neutron precursors. Of these, approx.85 have measured and evaluated emission probabilities (Pn's) and approx.34 have measured spectra data; the latter account for 80% or more of the total anti ..nu../sub d/. Although the measurements are probably adequate for most reactor applications, complete data sets are needed for ENDF/B and for fission product yield evaluations. This paper briefly describes the use of systematics and nuclear models used to produce a complete set of data for 272 precursors and presents aggregate summation calculations needed to produce the conventional six time-group approximations. 10 refs., 2 figs.