Investigation of thermal neutron flux perturbation in a polyethylene medium by use of gold foil detectors

Abstract

The neutron flux perturbation in a homogeneous thermal reactor, polyethylene moderated, was investigated experimentally through use of activated gold foils of varying thicknesses. The experimental data are compared with the theoretical predictions of Bothe and Skyrme, and with the modifications introduced by Tittle and by Ritchie and Eldridge. Experimental determination of the thermal neutron flux at the center of the core of the AGN-201 reactor indicates that Skyrme's theory and/or Skyrme's theory as modified by Ritchie and Eldridge give the best results over a range of foil thickness from two to ten mils. The greatest deviation of theoretical calculations from experimental data is less than 3%. Determination of other investigators for gold dtectors in graphite agree to within 3% with the predictions of the Skyrme theory. In water-moderated reactors experimental determinations have been compared with the Skyrme theory as modified by Ritchie and Eldridge and found to agree to 5%. The writers wish to express their appreciation to Professor William W. Hawes of the U.S. Naval Postgraduate School for his patient assistance and encouragement during this investigation.