Fission Product Decay Characteristics
AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
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This theses determined fission product decay characteristics , including the total activity, the gamma-ray emission rate GER and gamma-ray energy spectra. The activity and GER decay were compared to Way and Wigners texp-1.2 approximation, and the effects the spectra, activity and GER have on the Source Normalization Constant K were examined. Most of the fission product data were obtained from DKPOWR, and were compared with data obtained from ORIGIN2. Since the gamma rays are of primary concern in fallout studies, the GER is used instead of activity. The ratio of GER to activity changes significantly with time. The results of this study calculate a GER of 590 x 10 to the 16th power gamma rayssecond per kT of fission yield from U-235 fuel and a K of 7059 RHrkTsq.km.. The calculation of K includes the contribution from scattered photons. The GER result is 11 higher than reference values, while the K is within 2 of the current value in Glasstone and Dolans The Effects of Nuclear Weapons. The Ks for Pu-239 and U-238 were within 5 of the U-235 results. The wax-wigners texp-1.2 approximation differs from time dependent GER and K up to 85 for times less than 6 months. The approximation is not valid for the GER or K at times greater than 6 months. The approximation is within about 45, for the activity from fission product decay to at least 5 years. A more accurate measure of exposure requires a numerical integration of the time dependent GER and Source Normalization Constant. Keywords Fallout Source normalization constant Residual radioactivity Fission product decay.
- Radioactivity, Radioactive Wastes and Fission Products
- Radiation Pollution and Control