A replacement thermal sleeve with a flange for a reactor vessel closure head penetration adapter housing. By altering a diameter of the flange, a replacement thermal sleeve can be installed through the narrow diameter of the penetration adapter housing opening from under the reactor vessel head. The flange can be compressible or expandable or the tubular wall of the thermal sleeve can be inserted in longitudinal sections, one at a time, into an opening in the underside of the penetration head adapter and reformed within the opening when fully inserted.

A replacement thermal sleeve with a flange for a reactor vessel closure head penetration adapter housing. By altering a diameter of the flange, a replacement thermal sleeve can be installed through the narrow diameter of the penetration adapter housing opening from under the reactor vessel head. The flange can be compressible or expandable or the tubular wall of the thermal sleeve can be inserted in longitudinal sections, one at a time, into an opening in the underside of the penetration head adapter and reformed within the opening when fully inserted.

A method of determination of a nuclear core loading pattern defining the disposition of fuel assemblies includes definition of at least one potential core loading pattern, calculation of predictive bowing of the fuel assemblies at the end of the operation cycle for each potential core loading pattern, the calculation being carried out by an automatic learning algorithm trained on a training data set comprising a plurality of others loading patterns and, for each of them, the measures of bowing of fuel assemblies at the end of cycle, evaluation of the at least one core loading pattern based on the predictive bowing calculations and at least one predetermined criteria, and selection of one of the potential core loading patterns.

A method for peening an obstructed region of a metal assembly that is obstructed by an obstructing part of the metal assembly is provided. The method includes determining an optimal peening path for treating the obstructed region irrespective of the obstructing part; identifying a portion of the obstructing part within the optimal peening path; determining a section of the portion of the obstructing part that is removable without affecting a mechanical integrity and functionality of the obstructing part; removing, by machining, the section so as to create additional space along the optimal peening path; and peening the obstructed region, a path of the peening at least partially crossing through the additional space. A method for peening a nuclear reactor pressure vessel is also provided.

A modular nuclear reactor system includes a lift-out, replaceable nuclear reactor core configured for replacement as a singular unit during a single lift-out event, such as rather than lifting and replacing individual fuel assemblies and/or fuel elements. The system includes a reactor vessel and a power generation system configured to convert thermal energy in a high temperature working fluid received from the reactor vessel into electrical energy. The reactor vessel includes: a vessel inlet and an adjacent vessel outlet arranged near a bottom on the vessel; a vessel receptacle configured to receive a unified core assembly; locating datums in the base of the vessel receptacle and configured to constrain a core assembly in multiple degrees of freedom; and an interstitial zone surrounding the vessel receptacle and housing a set of control or moderating drums.

A modular nuclear reactor system includes a lift-out, replaceable nuclear reactor core configured for replacement as a singular unit during a single lift-out event, such as rather than lifting and replacing individual fuel assemblies and/or fuel elements. The system includes a reactor vessel and a power generation system configured to convert thermal energy in a high temperature working fluid received from the reactor vessel into electrical energy. The reactor vessel includes: a vessel inlet and an adjacent vessel outlet arranged near a bottom on the vessel; a vessel receptacle configured to receive a unified core assembly; locating datums in the base of the vessel receptacle and configured to constrain a core assembly in multiple degrees of freedom; and an interstitial zone surrounding the vessel receptacle and housing a set of control or moderating drums.

The present application relates to a spherical object falling buffer device including a flow-limiting pipe assembly and a central column assembly; wherein the flow-limiting pipe assembly includes a flow-limiting pipe, a redirecting joint and a sphere outlet pipe; a diameter of the flow-limiting pipe is greater than that of the sphere outlet pipe, and an inner surface of the redirecting joint is a conical surface; the central column assembly includes at least a central column arranged in the flow-limiting pipe; a flow-guiding region is provided between the flow-limiting pipe and the central column, and a plurality of gravity flow guide grooves are provided on an outer peripheral surface of the central column. The spherical object falling buffer device may restrict, guide and buffer spherical objects during falling, and avoids collision damage of the spherical objects or the stock bin due to the excessive falling speed of the spherical objects.

A replacement thermal sleeve with a flange for a reactor vessel closure head penetration adapter housing. By altering a diameter of the flange, a replacement thermal sleeve can be installed through the narrow diameter of the penetration adapter housing opening from under the reactor vessel head. The flange can be compressible or expandable or the tubular wall of the thermal sleeve can be inserted in longitudinal sections, one at a time, into an opening in the underside of the penetration head adapter and reformed within the opening when fully inserted.

A replacement thermal sleeve with a flange for a reactor vessel closure head penetration adapter housing. By altering a diameter of the flange, a replacement thermal sleeve can be installed through the narrow diameter of the penetration adapter housing opening from under the reactor vessel head. The flange can be compressible or expandable or the tubular wall of the thermal sleeve can be inserted in longitudinal sections, one at a time, into an opening in the underside of the penetration head adapter and reformed within the opening when fully inserted.

An example for continuous removal of fission products from a molten-salt fueled nuclear reactor enclosed in a reactor containment may include separating actinides from other fission products flowing out of the reactor, returning the separated actinides back to the reactor to be consumed, and removing the other fission products out of the containment while the reactor is operating. In various embodiments, the reactor can be a critical reactor, a subcritical (e.g., accelerator-drive) reactor, or another type of reactor.