Dose Uncertainty Quantification in AGC Experiment

Abstract

This memorandum formally documents completion of the Advanced Reactor Technologies Level 3 Milestone (M3NT-18IN060504037), “Interoffice Memorandum detailing status of the AGC irradiation uncertainty analysis” due SeptemberAugust 30, 2018. This memorandum details the progress made toward the issuance of a final report detailing the AGC uncertainty analysis including the proposed methodology, progress on activities, and explanation of how the data will be used. Radiation damage estimation is an important component of the post-irradiation analysis of the AGC experiments. It depends primarily on the fast fluence, which is determined using well-established methods of spectral adjustments. These are based on best estimates from models (e.g. MCNP). Input cross-sections, and measured activities from flux wires in the experiment, propagate uncertainties in each of these. While the methods of propagating uncertainty are well-established, the final uncertainty estimates they provide are only as good as the estimates of uncertainty in the inputs on which they are based. The purpose of this work is to implement a method that eliminates some deficiencies in the ways input uncertainties are presently estimated. The rRadiation damage estimates for the AGC experiments are ostensibly based on experimental data in the form of flux wire activation measurements; each AGC experiment has been instrumented with flux wires at various locations along the axial length to provide this data. However, the estimatesy also depend on the results of MCNP calculations. To understand why, consider that the objective of the analysis is to estimate some number of parameters (the energy group fluences ?_i) that best reproduce the observations (the measured activities of the flux wires a_i).