Memorial-Index-Based Inverse Kinetics Method for Continuous Measurement of Reactivity and Source Strength

Abstract

A new neutron inverse kinetics method has been proposed to compute both reactivity and source strength using only noise-containing reactor power signals in a subcritical state. The method is applicable to cases when the effective source strength varies with a change in reactivity. A newly defined kinetics parameter, “Memorial Index”, is introduced to detect properly the start and end of a transient and to exclude time intervals that are ill-posed for numerical source strength estimation analysis based on the grouping method. Results for a numerical simulation analysis demonstrate that the revised analytic procedure incorporated with the Memorial Index enables one to continuously calculate precise values of both source strength and reactivity during a complicated subcriticality transient.

KEYWORDS:

• inverse neutron kinetics
• subcritical
• reactivity
• effective source strength
• noise
• the grouping method
• Memorial Index
• delayed neutrons