An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shut-down or start-up phase of the conversion installation.

The present invention relates to nuclear fuel pellets and a manufacturing method thereof, and more particularly, to nuclear fuel pellets comprising a trapping material of fission gas and a manufacturing method thereof. A nuclear fuel pellet of the present invention comprises a nuclear fuel; and a trapping material of fission gas, wherein the trapping material of the fission gas includes an oxide containing at least one element selected from the group consisting of silicon (Si), aluminum (Al) and barium (Ba) to exhibit an excellent trapping ability selective and independent for fission gas.

The present invention relates to nuclear fuel pellets and a manufacturing method thereof, and more particularly, to nuclear fuel pellets comprising a trapping material of fission gas and a manufacturing method thereof. A nuclear fuel pellet of the present invention comprises a nuclear fuel; and a trapping material of fission gas, wherein the trapping material of the fission gas includes an oxide containing at least one element selected from the group consisting of silicon (Si), aluminum (Al) and barium (Ba) to exhibit an excellent trapping ability selective and independent for fission gas.

Described herein are systems and methods for imaging the top surface of a fuel pellet to observe the formation of radial cracks employing resistive heating to volumetrically heat the fuel pellet, but instead of passing the current axially through the pellet, electrodes were placed on the sides of a single pellet to pass the current transversely across the pellet allowing for an unobstructed view of the top surface of the pellet.

Described herein are systems and methods for imaging the top surface of a fuel pellet to observe the formation of radial cracks employing resistive heating to volumetrically heat the fuel pellet, but instead of passing the current axially through the pellet, electrodes were placed on the sides of a single pellet to pass the current transversely across the pellet allowing for an unobstructed view of the top surface of the pellet.

A green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

A green body for a 3D ceramic and/or metallic body is produced by providing a metal or a mixture of metals and/or a metalloid and/or a non-metal or mixtures thereof in form of at least one aqueous solutions, such as a metal nitrate solution; if more than one aqueous solutions are provided, they differ in composition and/or isotope concentration. One aqueous metal solution is mixed with a gelation fluid at a first temperature to suppress an internal gelation of the feed solution mixture prior to its ejection. The feed solution mixture is ejected by inkjet printing to the green body under construction. The ejected feed solution is heated mixture on the green body to a second temperature to fix it on the green body under construction. Several process steps are repeated according to a 3D production control model until a desired form of the green body is attained.

The present disclosure relates to a pellet containing an oxide additive to improve a nuclear-fission-gas-adsorption ability of a uranium-dioxide pellet used as nuclear fuel and increase the grain size thereof, and to a method of manufacturing the same. A La.sub.2O.sub.3—Al.sub.2O.sub.3—SiO.sub.2 sintering additive is added to uranium dioxide so that mass movement is accelerated due to the liquid phase generated during sintering of the uranium-dioxide pellet, which promotes the growth of grains thereof. Further, since less volatilization occurs during sintering due to the low vapor pressure of the liquid phase, efficient additive performance is exhibited, so the liquid phase surrounding the grain boundary effectively adsorbs cesium, which is a nuclear fission gas.

The known fully ceramic microencapsulated fuel (FCM) entrains fission products within a primary encapsulation that is the consolidated within a secondary ultra-high-temperature-ceramic of Silicon Carbide (SiC). In this way the potential for fission product release to the environment is significantly limited. In order to extend the performance of this fuel to higher temperature and more aggressive coolant environments, such as the hot-hydrogen of proposed nuclear rockets, a zirconium carbide matrix version of the FCM fuel has been invented. In addition to the novel nature to this very high temperature fuel, the ability to form these fragile TRISO microencapsulations within fully dense ZrC represent a significant achievement.

The known fully ceramic microencapsulated fuel (FCM) entrains fission products within a primary encapsulation that is the consolidated within a secondary ultra-high-temperature-ceramic of Silicon Carbide (SiC). In this way the potential for fission product release to the environment is significantly limited. In order to extend the performance of this fuel to higher temperature and more aggressive coolant environments, such as the hot-hydrogen of proposed nuclear rockets, a zirconium carbide matrix version of the FCM fuel has been invented. In addition to the novel nature to this very high temperature fuel, the ability to form these fragile TRISO microencapsulations within fully dense ZrC represent a significant achievement.