A Novel Experimental Method for Validating Neutron Initiation Probability

Abstract

A novel experimental method is introduced for effectively validating neutron initiation probability, through which the delayed neutron influence on the source strength can be neglected—this is the main reason for substantially explaining the burst waiting time experiments performed in the Godiva and Caliban burst reactors. The key idea of the new method is that the burst is initiated by simultaneously injecting a pulse of neutrons with appropriate strength just as the reactor achieves prompt supercritical and tallied by judging whether or not the burst is initiated by the pulsed neutrons based on the measured data. The principle of the method is described using initiation theory. The Chinese Fast Burst Reactor–II (CFBR-II) structure and two sets of configurations for preliminary experiments are then described. Last, those two sets of preliminary experiments are carried out on CFBR-II in the state of 0.042 $ prompt supercritical, and results, including the typical picture and other important measured data, are provided in order to illustrate how the initiation probability can be validated. The initiation probability of 0.43 was determined by preliminary performing of 65 bursts, which is an ˜35% relative difference between the theoretic calculations and the experimental results. Some discussion and suggestions for possible follow-on work are provided.