Abstract: An accelerator-driven subcritical breeding reactor is operated with a neutron multiplication coefficient as large as possible in order to require a small input power from the accelerator, reducing its dimension and hence its cost and complexity. The beam-generated spallation neutron yield then becomes comparable to the fraction of delayed neutrons from the fissioned elements. This can be exploited to ensure an accurate on-line determination of the reactivity. Resulting changes can be adjusted with the help of neutron absorbing control rods and/or variations of the proton current. In addition, the temperature variations during operation can be continuously monitored and adjusted in order to avoid that the subcritical systems approaches too closely the (delayed) criticality condition and that the neutron multiplication coefficient remains within acceptable limits.

Abstract: A material is exposed to a neutron flux by distributing it in a neutron-diffusing medium surrounding a neutron source. The diffusing medium is transparent to neutrons and so arranged that neutron scattering substantially enhances the neutron flux to which the material is exposed. Such enhanced neutron exposure may be used to produce useful radio-isotopes, in particular for medical applications, from the transmutation of readily-available isotopes included in the exposed material. It may also be used to efficiently transmute long-lived radioactive wastes, such as those recovered from spent nuclear fuel. The use of heavy elements, such as lead and/or bismuth, as the diffusing medium is particularly of interest, since it results in a slowly decreasing scan through the neutron energy spectrum, thereby permitting very efficient resonant neutron capture in the exposed material.

Abstract: A material is exposed to a neutron flux by distributing it in a neutron-diffusing medium surrounding a neutron source. The diffusing medium is transparent to neutrons and so arranged that neutron scattering substantially enhances the neutron flux to which the material is exposed. Such enhanced neutron exposure may be used to produce useful radio-isotopes, in particular for medical applications, from the transmutation of readily-available isotopes included in the exposed material. It may also be used to efficiently transmute long-lived radioactive wastes, such as those recovered from spent nuclear fuel. The use of heavy elements, such as lead and/or bismuth, as the diffusing medium is particularly of interest, since it results in a slowly decreasing scan through the neutron energy spectrum, thereby permitting very efficient resonant neutron captures in the exposed material.

Abstract: A gas, e.g. hydrogen, at relatively low pressure is directly heated by the fission fragments (FF) emitted by a thin layer of fissile material, e.g. 242mAm, deposited on the inner wall of a chamber which is kept cooled at a typical temperature of about 1,000/1,500 K. The gas is preferably emitted as capillary flow from the walls of cylindrical tubes. Its temperature progressively increases until it reaches an equilibrium value of the order of 9,500 K, at which point FF heating and radiative cooling balance. With a relatively modest surface power density at the foil of 200 W/cm2, the specific, volume-averaged power given to the H gas may be as large as 0.66 MWatt/g. Heating powers up to megawatts for each gram of gas are therefore feasible with acceptable foil surface heating. The gas heating method can be used in rocket engines for deep space propulsion.

Abstract: A surface coating material for heat collector elements (HCE) of solar plants, is a multi-layer structure comprising a lower infrared-reflecting metal layer, an upper layer of a non-reflecting material, and an intermediate layer of a composite ceramic-metallic (CERMET) material having upper and lower layers of different volumetric metal fractions. The lower layer has a volumetric metal fraction higher than that of the upper CERMET layer. The ceramic matrix of the CERMET is formed by amorphous silicon dioxide (SiO2). The reflecting metal layer has a thickness ranging from 90 to 110 nm. The lower CERMET layer has a thickness ranging from 70 to 80 nm and a volumetric metal fraction in the range from 0.45 to 0.55. The upper CERMET layer has a thickness ranging from 70 to 80 nm and volumetric metal fraction ranging from 0.15 to 0.25. The layer of anti-reflecting material layer has a thickness ranging from 65 to 75 nm.

Abstract: A solar concentrated module with a bidimensional parabolic profile geometry, comprises one or more rigid self-supporting panels having a parabolic cross section and a rectilinear longitudinal extension. The said panels comprise a central sandwich structure including a central honeycomb core and two thin outer skins of a high resistance material, forming a lightweight and particularly rigid construction. The panels adapted to support thin reflecting surfaces, the geometry of which is such as to concentrate incident sunlight rays along a longitudinal receiving tube, within which a fluid to be headed flows. An automated driver may be provided for moving the panels to follow the movement of the sun during the day.

Abstract: A gas, e.g. hydrogen, at relatively low pressure is directly heated by the fission fragments (FF) emitted by a thin layer of fissile material, e.g. 242m Am, deposited on the inner wall of a chamber which is kept cooled at a typical temperature of about {fraction (1,000/1,500)} K. The gas is preferably emitted as capillary flow from the walls of cylindrical tubes. Its temperature progressively increases until it reaches an equilibrium value of the order of 9,500 K, at which point FF heating and radiative cooling balance. With a relatively modest surface power density at the foil of 200 W/cm2, the specific, volume-averaged power given to the H gas may be as large as 0.66 MWatt/g. Heating powers up to megawatts for each gram of gas are therefore feasible with acceptable foil surface heating. The gas heating method can be used in rocket engines for deep space propulsion.

Abstract: A method for producing energy from a nuclear fuel material contained in an enclosure, through a process of breeding of a fissile element from a fertile element of the fuel material via a .beta.-precursor of the fissile element and fission of the fissile element. A high energy particle beam is directed into the enclosure for interacting with heavy nuclei contained in the enclosure so as to produce high energy spallation neutrons. The neutrons thereby produced are multiplied in steady sub-critical conditions by the breeding and fission process. The breeding and fission process is carried out inside the enclosure.