| abstract |
A self-powered fixed incore detector for a nuclear reactor has a neutron sensitive emitter element having a low neutron absorption cross section, such as a vanadium element, which extends the length of the active fuel region and generates a full length signal representative of full length power. A number of gamma sensitive emitter elements, preferably platinum but alternatively zirconium, cerium, tantalum, or osmium elements, provide sequentially increasing overlap with the neutron sensitive emitter element to define axial regions of the active fuel region and generate apportioning signals. The portion of the full length signal generated by the neutron sensitive emitter element attributable to each of the axial regions of the core are determined from ratios of the apportioning signals generated by the gamma sensitive elements. While the ratioing of the apportioning signals reduces the effects of delayed gamma radiation from the products of fission, the transient response can be further improved by filtering out this component of the apportioning signals generated by the gamma sensitive emitter elements. |