Fast-Neutron Hodoscope at TREAT: Data Processing, Analysis, and Results

Abstract

The fast-neutron hodoscope at the Transient Reactor Test Facility is designed for the determination of fuel motion during the course of brief (0.1- to 30-sec) power transients. During the course of a transient test, data must be recorded from each of 334 hodoscope channels at count rates up to 2 million/sec each, down to millisecond time intervals. This is accomplished in a relatively reliable and inexpensive manner by displaying counts from each detector sequentially in binary code on a lamp panel, which is photographed by a high-speed framing camera, producing a film record of the transient test. After chemical development, the film is examined by a computer-controlled flying-spot scanner, and the position and density of candidate lamp images are recorded on magnetic tape. Through further computer processing, these images are sorted and decoded, and the count rate is recovered for each detector at each instant of collection time. A cathode-ray tube and a plotter, both computer controlled, are used to recreate and analyze the fuel motion history of the experiment. Analysis is directed toward fuel distortion or expansion prior to clad failure, slumping, dispersion, amount and rates of movement, post-scram relocation, and ultimate disposition of fuel.