Provided is a water jet peening apparatus and a water jet peening method including: a clamping cylinder (201) which is able to be disposed at the outer peripheral side of an instrumentation nozzle (83) with a predetermined gap therebetween; a clamping piece (210) which is able to fix the clamping cylinder (201) to the instrumentation nozzle (83); a nozzle guide (221) which has a cylindrical shape, is provided inside the clamping cylinder (201), and is positioned to a position adjacent to the upper end of the instrumentation nozzle (83); an inner surface WJP nozzle (105) which is movable upward and downward inside the nozzle guide (221); and a drainage hole (224) which radially penetrates the nozzle guide (221). Accordingly, it is possible to improve the safety of the operation by preventing a thimble tube from being popped out due to a water jet peening operation.

Systems and methods for refueling a nuclear reactor that has a reactor core in a reactor pool having a plurality of elongated reactor core components, a fuel pool for storing core components, and a transfer channel connecting the fuel pool to the reactor pool. The method includes retrieving a replacement core component from the fuel pool, and securing the replacement core component in a first compartment of a handover assembly in a vertical position. The method also includes retrieving a spent core component from the reactor core, and securing the spent core component in a second compartment of the handover assembly in a vertical position. The replacement core component is retrieved from the first compartment and installed into the reactor core. The spent core component is retrieved from the second compartment and stored in a storage rack in the fuel pool.

Systems and methods for refueling a nuclear reactor that has a reactor core in a reactor pool having a plurality of elongated reactor core components, a fuel pool for storing core components, and a transfer channel connecting the fuel pool to the reactor pool. The method includes retrieving a replacement core component from the fuel pool, and securing the replacement core component in a first compartment of a handover assembly in a vertical position. The method also includes retrieving a spent core component from the reactor core, and securing the spent core component in a second compartment of the handover assembly in a vertical position. The replacement core component is retrieved from the first compartment and installed into the reactor core. The spent core component is retrieved from the second compartment and stored in a storage rack in the fuel pool.

A reactor measurement-pipe maintenance clamp apparatus includes a first clamp mechanism and a second clamp mechanism. The first clamp mechanism includes clamps to fix the measurement pipe between the clamps, first clamp operation bolts that are allowed to be turned by remote control from above a reactor core, and wedge mechanisms to convert the turning of the clamp operation bolts to displacement of the clamps in a radial direction of the diffuser to generate clamping forces for securing the measurement pipe. The second clamp mechanism includes a support clamp to hold the support, a second clamp operation bolt that is allowed to be turned by remote control from above the reactor core, and a wedge mechanism to convert the turning of the second clamp operation bolt to displacement of the support clamp in a tangential direction of the diffuser to generate clamping force for fixing the support.

Systems join with a control rod drive and expand or contract to displace elements necessary for decoupling. Joining structures affix to on sides of the control rod drive allow discriminatory jacking by a powered drive also in contact with the control rod drive. A moveable piston tube can be displaced by this jacking with hundreds or thousands of pounds of force with respect to the control rod drive. Probes and other instrumentation and sensors are useable in the systems to accurately measure any of piston tube displacement, temperature, malfunction; drive power status, displacement or speed; and communications status. Manual interaction with the systems are not required during the jacking, and installation and removal of the systems requires no tools or great amount of time or effort. Through remote operation and brief installation, human exposure to radiation about control rod drives is minimized.

A system for servicing a nuclear reactor module comprises a crane operable to attach to the nuclear reactor module, wherein the crane includes provisions for routing signals from one or more sensors of the nuclear reactor module to one or more sensor receivers.

A means for installing material, through a fuel assembly instrument thimble insert, into the existing instrument thimbles in nuclear fuel assemblies for the purpose of allowing the material to be converted to commercially valuable quantities of desired radioisotopes during reactor power operations during a remainder of a fuel cycle and removing the radioisotopes from the core through the reactor flange opening once the fuel assemblies have been removed for refueling. The invention also describes methods that can be used to harvest the irradiated material so it can be packaged for transportation from the reactor to a location where the desired radioisotope(s) can be extracted from the fuel assembly instrument thimble insert.

A means for installing material, through a fuel assembly instrument thimble insert, into the existing instrument thimbles in nuclear fuel assemblies for the purpose of allowing the material to be converted to commercially valuable quantities of desired radioisotopes during reactor power operations during a remainder of a fuel cycle and removing the radioisotopes from the core through the reactor flange opening once the fuel assemblies have been removed for refueling. The invention also describes methods that can be used to harvest the irradiated material so it can be packaged for transportation from the reactor to a location where the desired radioisotope(s) can be extracted from the fuel assembly instrument thimble insert.

Arrangements and devices for reducing and/or preventing wear of a thermal sleeve in a nuclear reactor are disclosed. Arrangements include a first structure provided on or in one the thermal sleeve and a second structure provided on or in the head penetration adapter. At least a portion of the first structure and at least another portion of the second structure interact to resist, reduce, and/or prevent rotation of the thermal sleeve about its central axis relative to the head penetration adapter. Devices include a base for coupling to a guide tube of the reactor and a plurality of protruding members extending upward from the base. Each member having a portion for engaging a corresponding portion of a guide funnel of the thermal sleeve.

A method for calculating a PCI margin associated with a loading pattern of a nuclear reactor including a core into which fuel assemblies are loaded according to the loading pattern is implemented by an electronic system. The fuel assemblies include fuel rods each including fuel pellets of nuclear fuel and a cladding surrounding the pellets. This method includes calculating a reference principal PCI margin for a reference loading pattern of the fuel assemblies in the core; calculating a reference secondary PCI margin for the reference pattern; calculating a modified secondary PCI margin for a modified loading pattern of the fuel assemblies in the core, and calculating a modified principal PCI margin for the modified pattern, depending on a comparison of the modified secondary PCI margin with the reference secondary PCI margin.