Application of Best Estimate and Analysis of Uncertainty Methods to CANDU Channel Power

Abstract

<p> Best estimate and analysis of uncertainty methods are used to examine the variability of the H factor, which converts the global flux in a lattice cell to power. The assumption of a constant H factor is tested, by examining the sensitivity of the components of the H factor to perturbations in reactor conditions, such as, moderator temperature, boron content in the moderator, moderator purity, RIH temperature, ROH pressure, and exit burnup. The local flux profile, which is a component of the H factor, is calculated for a typical CANDU reactor lattice cell using WIMS 2.5d. Another component of the H factor, the distribution of fission energy in a lattice cell, is found by exploring the location of each source of energy released from a fission event. To examine the location of the gamma ray energy deposition a two dimensional Monte Carlo code was created and subsequently benchmarked against an analysis done by C.R.Boss. Using the Monte Carlo code, the best estimate of the percentage of gamma ray energy deposited in the heat transport system was found to be 83.7%. The moderator temperature and the exit channel burnup are shown to have the largest influence on the H factor, which was found to vary between 99.6% and 100.4% of the best estimate value.</p>