This invention generally concerns radioactive decontamination of deposits on components in a nuclear power plant and is specifically concerned with improved compositions, systems and methods for disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. The methods include identifying the structure, taking the structure out of operational service, contacting the structure with an aqueous solution (e.g., a recirculating flow or static immersion), and adding an effective amount of elemental metal in solid form to the aqueous solution.

This invention generally concerns radioactive decontamination of deposits on components in a nuclear power plant and is specifically concerned with improved compositions, systems and methods for disrupting, dissolving, removing and reducing at ambient temperature radionuclides formed on the primary side surfaces of components in a pressurized water reactor and the internal components of a boiling water reactor. The methods include identifying the structure, taking the structure out of operational service, contacting the structure with an aqueous solution (e.g., a recirculating flow or static immersion), and adding an effective amount of elemental metal in solid form to the aqueous solution.

A photocatalyst injection system including: a reactor primary system coolant collection section collecting a reactor primary system coolant containing a noble metal or noble metal ion from a reactor primary system; a photocatalyst addition section adding a photocatalyst to the collected reactor primary system coolant; an ultraviolet irradiation section irradiating, with ultraviolet rays, the coolant to which the photocatalyst has been added for producing, in the coolant, a noble metal-carrying photocatalyst in which the noble metal is carried on a surface of the photocatalyst; and a noble metal-carrying photocatalyst injection section injecting the coolant containing the noble metal-carrying photocatalyst into the reactor primary system.

A photocatalyst injection system including: a reactor primary system coolant collection section collecting a reactor primary system coolant containing a noble metal or noble metal ion from a reactor primary system; a photocatalyst addition section adding a photocatalyst to the collected reactor primary system coolant; an ultraviolet irradiation section irradiating, with ultraviolet rays, the coolant to which the photocatalyst has been added for producing, in the coolant, a noble metal-carrying photocatalyst in which the noble metal is carried on a surface of the photocatalyst; and a noble metal-carrying photocatalyst injection section injecting the coolant containing the noble metal-carrying photocatalyst into the reactor primary system.

A plastically deformable almen strip is held under a predetermined underwater environment in which water jet peening is carried out, and a result of providing compressive residual stress in the water jet peening is confirmed by jetting water jet to the almen strip.

A subcritical reactivity monitor that utilizes one or more primarily gamma sensitive (prompt responding) self-powered detector style radiation measurement devices located within the core of a nuclear reactor to determine the amount that the reactor multiplication factor (K.sub.eff) is below the reactivity required to achieve or maintain a self-sustaining nuclear chain reaction. This invention utilizes measured changes in the self-powered detectors' current(s) to allow a reactor operator to measure the value of K.sub.eff at essentially any desired interval while the reactor is shutdown with a K.sub.eff value less than the critical value of 1.0. This invention will enable integration of the output of the value of K.sub.eff directly into the Reactor Protection System, which will enable the elimination of the operational and core design analysis constraint costs associated with the current Boron Dilution Accident prevention methodology and enable automatic control of the Chemical Volume Control System.

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.

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.

Disclosed embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.

Disclosed embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.