Figure 1: Geometry of reactor.

A schematic of the imaging probe as described for the experimental set-up and geometry of the reactor core and materials. Access to the core was provided by a lift shaft usually used for transporting irradiation samples. Power and communications cabling linked the probe with data acquisition electronics and associated equipment. The detector position, that is, the image origin was located 25 cm vertically and 229 cm horizontally from the geometric centre of the core. A cuboidal air void labelled ‘tunnel void’ located between the probe and the water coolant allowed the unshielded passage of radiation from the core region to the probe. A projection of a neutron image obtained in this work is included to provide a visualization of the information the technique provides.