Abstract: Medical isotopes are produced using a lower power, low cost nuclear reactor which permits the use of all the fission products produced in the reactor. Medical isotopes such as Molybdenum-99 are produced in a reactor operating at a power of 100 to 500 kilowatts.

Abstract: A hydrogenous moderated thermionic nuclear reactor operating in the thermal neutron energy region. Thermionic fuel elements are formed from multiple concentric cylinders. The center cylinder is a combination heat pipe and thermionic converter collector. The second cylinder is the converter emitter. The third cylinder is the nuclear fuel. The outer cylinder is the physical barrier between the fuel element and moderator. Between the outer radius of the fuel and outer cylinder is a gap containing multi-foil insulation. The insulation acts as a thermal barrier between the fuel and the outer cylinder and accommodates fuel expansion. This also causes heat flow to be radially inward from the fuel to the center converter/heat pipe.

Abstract: A method of measuring reactivity of a nuclear reactor includes automatic normalization. Normalization is achieved by determining the ratio of a linear amplifier used to form an analog detection signal, before and after a range change has taken place. A normalization factor is calculated according to this ratio which is applied to a delay neutral precursor concentration used for calculating the reactivity period.

Abstract: A control system for a nuclear reactor using an algorithm having a time cycle which is short compared with the delayed neutron lifetimes in the reactor. The use of a "stepping drive" or actuator to change an operating parameter by a fixed unit permits changes in the reactivity of the reactor. The short time cycle of the algorithm allows an evaluation of the reactor and actuation of the stepping drive or actuator during a very short period of time. The algorithm includes digital topology permitting the use of non-linear response functions in the determination of the required change in reactivity or period.

Abstract: A monitoring system 10 for providing a display 38 of the margin between actual and saturation pressure as well as a display 68 between actual and saturation temperature for the cooling fluid of a nuclear reactor. The system 10 also has an alarm 46 which is set off whenever the pressure margin to saturation pressure reaches a predetermined limit as well as a temperature margin alarm 78 which sets off an alarm whenever the temperature margin to saturation temperature reaches a predetermined limit.

Abstract: A safety system (10) for shutting down a nuclear reactor under overload conditions is provided using a series of parallel-connected computing modules (14a, 14b, 14c, 14d, 14e) each of which receives data on a particular reactor parameter (P, T, .phi..sub.T, .phi..sub.B, W) and each of which produces a function [f(P), f(T), f(.phi..sub.T), f(.phi..sub.B), f(W)] indicating the percentage of maximum reactor load that the parameter (P, T, .phi..sub.T, .phi..sub.B, W) contributes. The various functions [f(P), f(T), f(.phi..sub.T), f(.phi..sub.B), f(W)] are added together to provide a control signal (S) used to shut down the reactor under overload conditions.

Abstract: A safety system (10) for shutting down a nuclear reactor under overload conditions is provided using a series of parallel-connected computer memory type look-up tables (14a, 14b, 14c, 14d, 14e) each of which receives data on a particular reactor parameter (P, T, .phi..sub.T, .phi..sub.B, W) and each of which has stored therein a precalculated functional value [f(P); f(T); F(.phi..sub.T); f(.phi..sub.B); f(W)] for that parameter indicative of the percentage of maximum reactor load that the parameter contributes. The various functional values [f(P); f(T); f(.phi..sub.T); f(.phi..sub.B); f(W)] corresponding to the actual measured parameters are added together to provide a control signal (S) used to shut down the reactor under overload conditions.

Abstract: In order to map the power distribution of a nuclear fuel element, a passive detector is laid along the fuel element in situ to record the residual radiation of the fuel element. The detector spatially records the residual radiation as an image in a radioactive reaction product. In the preferred embodiment, the detector comprises a cylindrical casing or wand enshrouding a material which converts incident gamma radiation having an energy level exceeding a preselected threshold to a correspondingly distributed neutron radiation field. The sheath encases a neutron field-sensitive activant, such as gold in the form of a filament longitudinally disposed in the casing. The image of the low-level radiation field can thereafter be analyzed according to relatively risk-free techniques to map the power distribution of the fuel element.