Uncertainty and sensitivity analysis of aspects of the neutronics of a prismatic block-type HTGR

Abstract

The International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on High Temperature Gas-cooled Reactors (HTGR) Uncertainty Analysis in Modelling (UAM) has been established aiming to study uncertainty propagation in HTGR modelling. One of the research outcomes of this CRP is to calculate sensitivity coefficients and to propagate uncertainties for the MHTGR-350 using various sensitivity and uncertainty methods. This CRP was launched due to a shift towards Best Estimate Plus Uncertainty (BEPU) methods for safety analysis rather than the conservative methods. It is imperative in BEPU analysis that a parameter and its confidence limits lie within the safety margins. SCALE has a suite of uncertainty codes that allow quantification of uncertainties. These codes include Sampler and CE TSUNAMI-3D, which are chosen because they have the capability to accommodate the double heterogeneity of HTGRs. The large graphite quantities and hexagonal geometry for the prismatic designs should be taken into consideration when selecting analysis codes for HTGRs.