109 results about "Fissile material" patented technology

A nuclear fuel element includes a core formed from a high density solid solution fissile material that is substantially free of carbon and void space. A cladding substantially surrounds the core.

A scintillator system is provided to detect the presence of fissile material and radioactive material. One or more neutron detectors are based on 6LiF mixed in a binder medium with scintillator material, and are optically coupled to one or more wavelength shifting fiber optic light guide media that have a tapered portion extending from the scintillator material to guide light from the scintillator material to a photosensor at the tapered portion. An electrical output of the photosensor is connected to an input of a first pre-amp circuit designed to operate close to a pulse shape and duration of a light pulse from the scintillator material, without signal distortion. The scintillator material includes a set of scintillation layers connected to the wavelength shifting fiber optic light guide media that guide light to the photosensor. Moderator material is applied around the set of scintillation layers increasing detector efficiency.

A system detects at least one of nuclear and fissile materials. The system includes a plurality of high speed scintillator detectors. Each high speed scintillator detector in the plurality of high speed scintillator detectors includes at least one photo sensor and a pre-amp circuit adapted to eliminate pulse stretching and distortion of detected light pulses emitted from scintillation material when interacting with neutron particles and/or gamma particles. An isotope database includes a plurality of spectral images corresponding to different known isotopes. An information processing system is adapted to compare spectral data received from each high speed scintillator detector to one or more of the spectral images and identify one or more isotopes present in an object or container being monitored.

A system and method detecting fissile material. According to one embodiment, a detector includes an array of active pixel sensors wherein each active pixel sensor operable to integrate a charge generated by radiation that is incident upon the active pixel sensor by using a charge-sensing element during an integration phase. Then, a voltage signal is generated that is based upon the integrated charge intensity during a readout phase. After reading out the voltage signal during the readout phase, the active pixel sensor is reset ready to integrate again. The integration phase is typically set to a time interval that is optimal for detecting radiation from fissile material, and the system is typically able to count individual events occurring in an integration period, and to digitally sum these event counts to measure rate of radiation events.

A scintillator system is provided to detect the presence of fissile material and radioactive material. One or more neutron detectors include scintillator material, and are optically coupled to one or more wavelength shifting fiber optic light guide media that extend from the scintillator material to guide light from the scintillator material to a photosensor. An electrical output of the photosensor is connected to an input of a pre-amp circuit designed to provide an optimum pulse shape for each of neutron pulses and gamma pulses in the detector signals. Scintillator material as neutron detector elements can be spatially distributed with interposed moderator material. Individual neutron detectors can be spatially distributed with interposed moderator material. Detectors and moderators can be arranged in a V-shape or a corrugated configuration.

Micro neutron detectors include relatively small pockets of gas including a neutron reactive material. During use, under a voltage bias in a neutron environment, neutron interactions in the neutron reactive material are seen to occur. Ultimately, electron-ion pairs form and positive ions drift to a cathode and electrons to the anode. The motion of charges then produces an induced current that is sensed and measurable, thereby indicating the presence of neutrons. Preferred pocket volumes range from a few cubic microns to about 1200 mm³; neutron reactive materials include fissionable, fertile or fissile material (or combinations), such as ²³⁵U, ²³⁸U, ²³³U, ²³²Th, ²³⁹Pu, ¹⁰B, ⁶Li and ⁶LiF; gasses include one or more of argon, P-10, ³He, BF₃, BF₃, CO₂, Xe, C₄H₁₀, CH₄, C₂H₆, CF₄, C₃H₈, dimethyl ether, C₃H₆ and C₃H₈. Arrangements include two- and three-piece sections, arrays (including or not triads capable of performing multiple detecting functions) and/or capillary channels.

Microstructured nuclear fuel adapted for nuclear power system use includes fissile material structures of micrometer-scale dimension dispersed in a matrix material. In one method of production, fissile material particles are processed in a chemical vapor deposition (CVD) fluidized-bed reactor including a gas inlet for providing controlled gas flow into a particle coating chamber, a lower bed hot zone region to contain powder, and an upper bed region to enable powder expansion. At least one pneumatic or electric vibrator is operationally coupled to the particle coating chamber for causing vibration of the particle coater to promote uniform powder coating within the particle coater during fuel processing. An exhaust associated with the particle coating chamber and can provide a port for placement and removal of particles and powder. During use of the fuel in a nuclear power reactor, fission products escape from the fissile material structures and come to rest in the matrix material. After a period of use in a nuclear power reactor and subsequent cooling, separation of the fissile material from the matrix containing the embedded fission products will provide an efficient partitioning of the bulk of the fissile material from the fission products. The fissile material can be reused by incorporating it into new microstructured fuel. The fission products and matrix material can be incorporated into a waste form for disposal or processed to separate valuable components from the fission products mixture.

Methods and systems for non-intrusively detecting the existence of fissile materials in a container via the measurement of energetic prompt neutrons are disclosed. The methods and systems use the unique nature of the prompt neutron energy spectrum from photo-fission arising from the emission of neutrons from almost fully accelerated fragments to unambiguously identify fissile material. The angular distribution of the prompt neutrons from photo-fission and the energy distribution correlated to neutron angle relative to the photon beam are used to distinguish odd-even from even-even nuclei undergoing photo-fission. The independence of the neutron yield curve (yield as a function of electron beam energy or photon energy) on neutron energy also is also used to distinguish photo-fission from other processes such as (γ, n). Different beam geometries are used to detect localized samples of fissile material and also fissile materials dispersed as small fragments or thin sheets over broad regions. These signals from photo-fission are unique and allow the detection of any material in the actinide region of the nuclear periodic table.

Apparatuses for reducing or eliminating Type 1 LOCAs in a nuclear reactor vessel. A nuclear reactor including a nuclear reactor core comprising a fissile material, a pressure vessel containing the nuclear reactor core immersed in primary coolant disposed in the pressure vessel, and an isolation valve assembly including, an isolation valve vessel having a single open end with a flange, a spool piece having a first flange secured to a wall of the pressure vessel and a second flange secured to the flange of the isolation valve vessel, a fluid flow line passing through the spool piece to conduct fluid flow into or out of the first flange wherein a portion of the fluid flow line is disposed in the isolation valve vessel, and at least one valve disposed in the isolation valve vessel and operatively connected with the fluid flow line.

The invention provides a liquid target system which comprises a beam current action zone and a neutron generating device arranged in the beam current action zone. The neutron generating device is made of fissile material. The output rate of neutrons can be effectively increased.

A pressurized water nuclear reactor (PWR) includes a pressure vessel having a lower portion containing a nuclear reactor core comprising a fissile material and an upper portion defining an internal pressurizer volume. A condenser is secured to, and optionally supported by, the upper portion of the pressure vessel. A condenser inlet is in fluid communication with the internal pressurizer volume. A heat sink is in fluid communication with the condenser such that the condenser operates as a passive heat exchanger to condense steam from the internal pressurizer volume into condensate while rejecting heat to the heat sink. A condenser outlet connects with the pressure vessel to return condensate to the pressure vessel. A single metal forging having a first end welded to the pressure vessel and a second end welded to the condenser inlet may provide the fluid communication between the condenser inlet and the internal pressurizer volume.

The invention provides a method using accelerators to produce radio-isotopes in high quantities. The method comprises: supplying a “core” of low-enrichment fissile material arranged in a spherical array of LEU combined with water moderator. The array is surrounded by substrates which serve as multipliers and moderators as well as neutron shielding substrates. A flux of neutrons enters the low-enrichment fissile material and causes fissions therein for a time sufficient to generate desired quantities of isotopes from the fissile material. The radio-isotopes are extracted from said fissile material by chemical processing or other means.

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.

A method and a system for fissile content measurement that utilizes a detector configured to detect fast neutrons. An external radiation source may be used to induce fission in a sample to allow the measurement of a fissile material of the sample with a low spontaneous fission probability. Analyzing the sample may be based on the energy spectrum of emitted neutrons. That is, the energy information regarding the energy of the fast neutrons is obtained, and the fast neutrons as having a high likelihood of originating in a nuclear fission process as opposed to originating in an (alpha,n) reaction by utilizing the obtained energy information are classified to analyze the sample. Alternatively, a position of interaction in the detector of neutron emitted by the sample is measured, and this position is retraced back through intervening material(s) between the detector and the sample to determine the spacial geometry of the sample.

A nuclear reactor includes a nuclear reactor core comprising fissile material and a pressure vessel containing the nuclear reactor immersed in primary coolant water at an operating pressure. The pressure vessel has a vessel penetration passing through a wall of the pressure vessel. An electrical feedthrough seals the vessel penetration and has an outside electrical connector mounted at the pressure vessel. The outside electrical connector is at atmospheric pressure. The electrical feedthrough may include a flange disposed inside the pressure vessel and sealing against an inside surface of the wall of the pressure vessel. The outside electrical connector of the electrical feedthrough may be inset into the wall of the pressure vessel.

A fully ceramic micro-encapsulated fuel assembly for a light water nuclear reactor includes a set of FCM fuel rods bundled in a square matrix arrangement. Fully ceramic micro-encapsulated fuel assemblies replace standard reference solid fuel assemblies with smaller number of FCM fuel rods that have a larger diameter than the diameter of the solid standard reference fuel rods, while keeping similar amounts of fissile material in the fuel assembly and maintaining comparable rates of burnup and number of EFPDs, and compatible power production, heat transfer and thermo-hydraulic features. A fully ceramic micro-encapsulated fuel rod includes multiple fully ceramic micro-encapsulated fuel pellets, which are comprised of tristructural-isotropic particles. In order to obtain compatible burnup rates with the standard reference fuel, the tristructural-isotropic particles have preferentially large diameter and packing fraction. Furthermore, Erbium oxide is included in the sintered mix of the SiC compact to serve as a burnable poison.

A nuclear reactor core comprising fissile material is surrounded by a core former. The core former comprises one or more single-piece annular rings wherein each single-piece annular ring comprises neutron-reflecting material. In some embodiments the core former comprises a stack of two or more such single-piece annular rings. In some embodiments the stack of single-piece annular rings is self-supporting. In some embodiments the stack of single-piece annular rings does not include welds or fasteners securing adjacent single-piece annular rings together. A core basket may contain the nuclear reactor core and the core former, and in some embodiments an annular gap is defined between the core former and the core basket. In some embodiments the core former does not include welds and does not include fasteners.

A pressurized water reactor (PWR) comprises: a nuclear core comprising a fissile material; a cylindrical pressure vessel having a vertically oriented cylinder axis and containing the nuclear core immersed in primary coolant water; and a hollow cylindrical central riser disposed concentrically with and inside the cylindrical pressure vessel. A downcomer annulus is defined between the hollow cylindrical central riser and the cylindrical pressure vessel. The hollow cylindrical central riser has a radially expanding upper orifice that merges into an annular divider plate that separates an upper plenum above the annular divider plate from a lower plenum below the annular divider plate. The upper plenum is in fluid communication with the radially expanding upper orifice and the lower plenum is in fluid communication with the downcomer annulus. A weir may extend away from a bottom wall of the lower plenum into the lower plenum. An emergency core cooling system (ECCS) return line nozzle may be arranged to inject water into the upper plenum. A pump support plate spans the inner diameter of the cylindrical pressure vessel and forms a portion of the pressure boundary of the cylindrical pressure vessel, and reactor coolant pumps (RCPs) are supported by the pump support plate. Alternatively, reactor coolant pumps (RCPs) are supported by an arcuate annular ledge formed in the upper portion of the cylindrical pressure vessel.

A packaging device, for bulk transport of uraniferous fissile materials. The device comprises an internal chamber (10) forming a confinement enclosure for the fissile materials it contains. This is advantageously made of high-density polyethylene. It is placed inside a container (12) formed by an external envelope (26) and an inner shaft (28) separated by a cellular material for thermo-mechanical protection, such as a phenolic foam. The design of the container (12) enables deformation of the chamber (10) likely to break the confinement of the fissile material to be limited, in the event of shock.

The invention provides methods for the production of radioisotopes or for the treatment of nuclear waste. In methods of the invention, a solution of heavy water and target material including fissile material present in subcritical amounts is provided in a shielded irradiation vessel. Bremsstrahlung photons are introduced into the solution, and have an energy sufficient to generate photoneutrons by interacting with the nucleus of the deuterons present in the heavy water and the resulting photoneutrons in turn cause fission of the fissile material. The bremmssrrahlung photons can be generated with an electron beam and an x-ray converter. Devices of the invention can be small and generate radioisotopes on site, such as at medical facilities and industrial facilities. Solution can be recycled for continued use after recovery of products.

A nuclear reactor includes a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having vessel penetrations that exclusively carry flow into the nuclear reactor and at least one vessel penetration that carries flow out of the nuclear reactor. An integral isolation valve (IIV) system includes passive IIVs each comprising a check valve built into a forged flange and not including an actuator, and one or more active IIVs each comprising an active valve built into a forged flange and including an actuator. Each vessel penetration exclusively carrying flow into the nuclear reactor is protected by a passive IIV whose forged flange is directly connected to the vessel penetration. Each vessel penetration carrying flow out of the nuclear reactor is protected by an active IIV whose forged flange is directly connected to the vessel penetration. Each active valve may be a normally closed valve.