Analysis of Uncertainties in Summation Calculations of Decay Heat Using JNDC FP Nuclear Data Library.

Abstract

Uncertainties of decay heat summation calculations are derived for the thermal fission of 235U and 239Pu and the fast fission of 238U through sensitivity analyses using data given in the JNDC FP nuclear data library. The uncertainties analyzed are those relevant to decay energies, fission yields and decay constants among the nuclear data contained in the summation calculation. For nuclides lacking complete experimental data, the uncertainties of the decay energies are theoretically calculated. Thus analyzed, the maximum uncertainties of burst fission are 2.8 % for 235U, 3.2%” for 239Pu and 4.2% for 238U in the range of cooling time between 1 and 109s, and in the case of infinite irradiation, the corresponding level of maximum uncertainty is below 1.6% for all three fissioning nuclides.