Abstract: A neutron detector array is capable of measuring a wide range of neutron fluxes. The array includes multiple semiconductor neutron detectors. Each detector has a semiconductor active region that is resistant to radiation damage. In one embodiment, the array preferably has a relatively small size, making it possible to place the array in confined locations. The ability of the array to detect a wide range of neutron fluxes is highly advantageous for many applications such as detecting neutron flux during start up, ramp up and full power of nuclear reactors.

Abstract: A radiation resistant solid state neutron detector is disclosed. The detector uses a neutron convertor material such as boron or lithium to react with neutrons to create charged particles that are received in a semiconductor active region of the detector. The active thickness of the detector is smaller than the range of the charged particles. Since most of the radiation damage produced by impinging charged particles occurs near the end of the range of the particles, displacement damage predominantly occurs outside of the active region. Although the charged particles pass through the semiconductor material, the particles cause electron excitation within the semiconductor material which is detected in the form of an electronic pulse. A preferred semiconductor material for the active region is silicon carbide.

Abstract: A fuel assembly in a nuclear reactor has a spectral shift apparatus including a plurality of displacer rods for controlling reactivity in the assembly and an apparatus for refurbishing the displacer rods for reuse. Each displacer rod contains a quantity of water equivalent to a small fraction of the rod volume. Also, the spectral shift apparatus includes a manifold with a central plenum and a rupturable disk connected to the manifold. The manifold is connected in flow communication with the displacer rods. The disk which seals the displacer rods as well as the manifold plenum is rupturable at a given pressure differential thereacross so as to allow entry of the moderator/coolant liquid into the manifold and rods. Also, a screen adjacent the disk restricts it to rupturing in one direction only.