Fission Product Analytic Impulse Source Functions

The intensive study of fission products and their effects carried out over the past decade has resulted in a thorough understanding of their behavior and an accurate predictive capability. A convenient form, a fitted linear combination of exponentials, has been developed for representing aggregate time-dependent decay spectra. The resulting parameters are useful in a wide variety of fission product applications. The fitted functions, which include beta and gamma aggregate spectra for total and gaseous fission products from ²³⁵U and ²³⁹Pu over the 0- to 10⁹-s time interval, are readily used with any power history.