Average beta and gamma decay energies of the fission products

One method of predicting the decay-heat is the 'Summation Method' in which the power produced by decay of each fission product at time t after shut-down is calculated. The reactor shut-down power produced at time t is then obtained by summing over all of the fission products. An accurate determination of the average beta and gamma decay energies is essential for the success of this method. Two summation method calculations were performed using ROPEY, a summation method code. Treating other input parameters, namely, half-lives, branching ratios, and independent nuclear fission product yields as fixed, decay-heat calculated compared better than a calculation using the existing Evaluated Nuclear Data File B-IV did with the American Nuclear Society Decay-Heat Standard for the decay time between 1 and 60 seconds. Between 60 and 10,000 seconds of decay time experimental data dominate the results, which are virtually identical.