Abstract: System for confining and cooling melt from the core of a water-moderated nuclear reactor comprising a melt trap. The melt trap is installed in the reactor vessel bottom and provided with a cooled containment, consisting of outer and inner housings between which there is a sealant, and the filler for the melt dilution placed in the melt trap inner body. The melt trap inner body has a damper consisting of a central mantle, bearing ribs connected with the central mantle, titled plates, placed between the bearing ribs, the stops providing fastening of the damper to the melt trap body.

Abstract: A method regulates operating parameters comprising at least the mean temperature of the core (Tm), and the axial power (AO) imbalance. The method includes development of a vector (US) of control values of the nuclear reactor by a supervisor (31) implementing a predictive control algorithm; development of a vector (uK) of corrective values of the nuclear reactor controls by a regulator (33) implementing a sequenced gain control algorithm; development of a vector (U) of corrected values of the commands of the nuclear reactor, by using the vector (US) of the values of the commands produced by the supervisor (31) and the vector (uK) of the corrective values of the commands produced by the regulator (33); and regulation of the operating parameters of the nuclear reactor, by controlling actuators using the vector (U) of the corrected values of the controls.

Abstract: A method for the manufacture of Actinium-225 from a Radium-226 containing material. Radium-226 containing starting target material is shielded with a thermal neutron absorption shield and is subjected to neutron irradiation from a moderated nuclear reactor. Radium-226 is thereby converted into Radium-225 to provide a Radium-225-containing material. The Radium-225 in the Radium-225 containing material is allowed to decay into Actinium-225, and the Actinium-225 is isolated from the Radium-225 containing material. The neutron absorption shield shields the starting target material from neutrons having an energy in the range of 20 eV to 1000 eV.

Abstract: An equatorial anthropic radiation source and a method of making an equatorial anthropic radiation source are described. The radiation source is useful in diagnostic imaging applications in healthcare or other industries (e.g. computerized three-dimensional segmental imaging; Crompton scattering imaging techniques; radiation detector check and calibration, in particular CdZnTe detectors commonly used in medical imaging).

Abstract: Disclosed is a method of measuring a number of environmental conditions with a transmitter device, said transmitter device comprising a neutron detector structured to generate electrical current from neutron flux, an oscillator circuit comprising an electrostatic switch electrically connected to said neutron detector, and an antenna electrically connected with said electrostatic switch, wherein said electrostatic switch is moveable based on said neutron detector, wherein said oscillator circuit is structured to pulse said antenna based on said neutron detector, wherein a period between pulses is related to the neutron flux, the method comprising the steps of: generating the electrical current with said neutron detector, storing energy in said oscillator circuit until a trigger voltage of said electrostatic switch is reached, and emitting a signal with said antenna corresponding to a number of characteristic values of said oscillator circuit.

Abstract: A nuclear reactor includes a vessel having an outer wall and vessel bottom, and an enclosure delimited by a cylindrical inner wall disposed inside the vessel such that the inner wall and outer wall define a circuit with an annular cross-section. A support element is located adjacent the bottom of the enclosure to hold control elements of the core. A flow diffusion element is positioned between the support element and the vessel bottom and has a circular flat surface portion including disc shaped orifices of the same diameter. The space between the flat portion and the vessel bottom forms an unobstructed mixing zone to allow uniform distribution of flow rates of fluid circulated through the enclosure.

Abstract: A feedwater sparger repair assembly includes a cover plate having a partial cylindrical shape and having a nozzle opening and a pair of bolt openings extending through the cover plate. A nozzle is attached to the cover plate and surrounds the nozzle opening. A pair of T-bolts extend through a respective one of the pair of bolt openings and each include a shank having a threaded portion extending from an exterior side of the cover plate and a partial cylindrical head portion disposed at an end of the shank on an interior side of the cover plate. A pair of nuts are engaged with the threaded portion of the pair of T-bolts. The feedwater sparger repair assembly is adapted to be mounted to an opening that is cut into a core spray pipe in order to repair/replace a sparger that becomes cracked.

Abstract: Disclosed herein is a nuclear power plant main steam system that reduces the atmospheric discharge of radioactive materials generated in an accident. The system includes: a decontamination water tank containing decontamination water; and a connection pipe for connecting the decontamination water tank to a main steam pipe which connects a steam generator and a turbine. A main steam safety valve or a connection valve is provided as a three-way valve configured to discharge the generated steam to the atmosphere when an accident occurs within a design basis and to transfer the generated steam to the decontamination water tank when an accident involving damage to nuclear fuel occurs. The main steam system reduces discharge of radioactive materials to the atmosphere when a containment bypass accident (e.g., a steam generator tube rupture caused by high-temperature steam) occurs.

Abstract: Fission reactor has a shell encompassing a reactor space within which are a central longitudinal channel, a plurality of axially extending rings with adjacent rings defining an annular cylindrical space in which a first plurality of primary axial tubes are circumferential located. Circumferentially adjacent primary axial tubes are separated by one of the plurality of secondary channels and a plurality of webbings connects at least a portion of the plurality of primary axial tubes to adjacent structure. A fissionable nuclear fuel composition is located in at least some of the plurality of secondary channels and a primary coolant passes thorough at least some of the primary axial tubes. Additive and/or subtractive manufacturing techniques produce an integral and unitary structure for the fuel loaded reactor space. During manufacturing and as-built, the reactor design can be analyzed using a computational platform that integrates and analyzes data from in-situ monitoring during manufacturing.

Abstract: A damping area or “dash pot” on the upper ends of control rods absorb energy from dropped control rod assemblies without narrowing the diameter of guide tubes. As a result, coolant can freely flow through the guide tubes reducing boiling water issues. The dampening area reduces a separation distance between an outside surface of the control rod and an inside surface of the guide tubes decelerating the control rods when entering a top end of the guide tubes. In another example, the dampening area may be located on a drive shaft. The dampening area may have a larger diameter than an opening in a drive shaft support member that decelerates the drive shaft when dropped by a drive mechanism.

Abstract: A temperature measurement sensor for use in a nuclear reactor is described. The sensor includes a first neutron detector member and a second neutron detector member. The first neutron detector includes an outer shield material with an effective neutron capture cross section that is temperature dependent. The first neutron detector member outputs a first current signal and the second neutron detector member outputs a second current signal. An electrical connection between the first and second neutron detector members produces a net current that is the difference in current between the first and second signals. The difference is proportional to changes in temperature.

Abstract: A method of generating power using a Thorium-containing molten salt fuel is disclosed. One example includes the steps of providing a vessel containing a molten salt fuel, generating a proton beam externally to the vessel, where the externally generated proton beam is of an energy level sufficient to interact with material within a fuel rod in the vessel to produce (p, n) reactions resulting in the generation of neutrons at a first energy level. Neutrons generated within the vessel through the (p, n) reactions are utilized to produce a fission reaction which increases the heat content of the molten salt within the vessel. In the example, a heat exchanger is used to extract heat from the molten salt within the vessel and power is generated from the extracted heat.

Abstract: A fast-neutron nuclear reactor fuel assembly having fuel rods. Each fuel rod has nuclear fuel disposed in a sealed housing in the form of a tubular steel shell and end parts. A steel spacer element is wound in a coil with a specific pitch on the outside surface of the shell and is fastened on the end parts. The spacer element is in the form of a metallic band twisted around its longitudinal axis. The width of said band is approximately equal to the minimum distance between adjacent fuel rods in the fuel assembly. A transverse cross-sectional area of the band is within a range from 0.10 to 0.50 times the area of a circle described around the width of the band.

Abstract: A closed-vessel molten salt reactor (cvMSR) is described herein. A cvMSR may comprise a suspended container, such as a metallic container, within a trench surrounded by a concrete enclosure and a concrete cover having a number of channels. The suspended container may be hollow and a solution of fissile materials and salt materials may be provided within the suspended container. The solution may be capable of undergoing a chain reaction nuclear fission process once a threshold temperature is reached. Heat generated by the solution may heat a fluid surrounding the suspended container. The heated fluid may be transported, through the number of channels of the concrete cover, to an external location where the heated fluid may be used in distributing heat and/or electricity generation.

Abstract: Microsized devices operable to emit neutrons in a selective manner are provided. The devices are configured so that the rate of neutron emission can be varied, either actively or passively. The devices comprise an a-particle emitting material and a neutron producing target material that when aligned and/or positioned a predetermined distance apart emit neutrons. The rate of neutron emission can be slowed or stopped by taking the materials out of alignment and/or attenuating the ?-particles being directed toward the neutron producing target material.

Abstract: A system includes a containment vessel configured to prohibit a release of a coolant, and a reactor vessel mounted inside the containment vessel. An outer surface of the reactor vessel is exposed to below atmospheric pressure, wherein substantially all gases are evacuated from within the containment vessel.

Abstract: A pit gate includes a gate body which is inserted between a pool portion storing water and a canal portion connected to the pool portion and is configured to change a flow state of the water, and a seal portion (6) which is accommodated in a groove-shaped accommodation recess formed in the gate body and seals between the pool portion and the gate body. The seal portion (6) includes a low-rigidity portion (10) which is relatively easily deformed by a load according to a water pressure from the pool portion side, and a high-rigidity portion (11) which is provided on the pool portion side of the low-rigidity portion and is not easily deformed relatively by the load.

Abstract: An improved retention system for retaining fuel rods in a fuel assembly is disclosed. The retention system includes a plurality of first engagement surfaces on the bottom nozzle of a fuel assembly. There is at least one engagement surface for each fuel rod. A second engagement surface is formed on the bottom end plug of each fuel rod. The first and second engagement surfaces are configured for engagement with each other for axially and laterally retaining each fuel rod within the fuel assembly. Debris deflectors may also be provided to deflect debris from coolant channels surrounding the fuel rods.

Abstract: A method for restraining a sleeve lining a tube passing through a nuclear reactor pressure vessel is provided. The method includes attaching in situ a radial protrusion on an external surface of the sleeve; and attaching a collar to an end of the tube and coupling the radial protrusion with the collar to retain the thermal sleeve in position.

Abstract: A nuclear fuel element includes a core comprising a fissile element and an additional element. A protective structure surrounds the core and comprises at least a first material surrounding the nuclear fuel. The first material comprises the fissile element and the additional element and comprises a greater than stoichiometric amount of the additional element. An outer portion of the nuclear fuel element comprises a metal. Related nuclear fuel elements, and related methods are also disclosed.