Abstract: An incore piping section maintenance system of a reactor comprises a maintenance system main body which is fixed to a maintenance target portion in a reactor pressure vessel or in the vicinity thereof to which a preventive-maintenance operation is executed, a support mechanism provided for the maintenance system main body so as to be movable in a reciprocal manner towards the maintenance target portion, a laser generator for generating a laser beam, a laser de-sensitization treatment apparatus which is rotatably supported around an axis of the support mechanism and which includes a laser irradiation section for irradiating the laser beam to the maintenance target portion, and an optical transmission element which guides the laser beam outputted from the laser generator to the laser de-sensitization treatment mechanism.

Abstract: An incore piping section maintenance system of a reactor comprises a maintenance system main body which is fixed to a maintenance target portion in a reactor pressure vessel or in the vicinity thereof to which a preventive-maintenance operation is executed, a support mechanism provided for the maintenance system main body so as to be movable in a reciprocal manner towards the maintenance target portion, a laser generator for generating a laser beam, a laser de-sensitization treatment apparatus which is rotatably supported around an axis of the support mechanism and which includes a laser irradiation section for irradiating the laser beam to the maintenance target portion, and an optical transmission element which guides the laser beam outputted from the laser generator to the laser de-sensitization treatment mechanism.

Abstract: An apparatus for inspection of a reactor pressure vessel uses a laser driven type underwater wall climbing robot guided by a laser pointer. The inspection apparatus uses a small and light underwater wall climbing robot for the quick and adequate inspection of weld lines of a reactor pressure vessel. Position control methods are provided for the stable guidance of the robot to desired three dimensional inspection positions on the reactor pressure vessel.

Abstract: The invention relates to a process for removing dust from at least one nuclear fuel pellet (7) having undergone a grinding operation, which has left on the pellet surface dust of the material from which said pellet is formed. The process comprises subjecting said surface to the impact of a laser beam (3) having characteristics suitable for bringing about the disincrustation of the dust from said surface, and eliminating from said surface the products resulting from the dust disincrustation.The invention also relates to an apparatus for performing this process.Application to the dust removal from MOX pellets.

Abstract: An underwater laser processing method is carried out by irradiating, through a laser beam irradiation apparatus, a laser beam having a high output, a short pulse and a visible wavelength to a surface of a structure immersed in a water to improve residual stress of a material of the surface of the structure and remove a crack or a CRUD thereof. The laser beam irradiation apparatus comprises a pulse laser device suspended into a water in which a metal material is accommodated from an upper side thereof for irradiating a laser beam having a visible wavelength to a processing position, a beam strength adjusting device for adjusting an output per 1 pulse of a laser beam generated by the pulse laser device and a mechanism for adjusting a spot diameter and a multiplexing ratio of an irradiated beam.

Abstract: A compact fission reactor generates a flux of fission fragments, fission neutrons, and gamma-ray photons. The flux excites a noble element converter medium which produces light. Optical means are provided for focusing the light onto an array of photovoltaic cells. The photovoltaic cells convert the light radiation into electrical energy for various load applications.

Abstract: In a method of treating a surface 12 of an object 10 contaminated with radionuclides 14, a laser source 16 is directed at the surface 12 to apply a local area 18 of intense heat to the surface 12. The laser source 16 is arranged to pass in a raster manner to cause local melting of the surface 12, surface 12 subsequently solidifying and fixing the radionuclides 14 therein. At least one layer of a coating material be applied before or after the application of the intense heat to fix and seal the radionuclides on or in the object.

Abstract: A control element for reactivity control of a fission source provides an atomic density of .sup.3 He in a control volume which is effective to control criticality as the .sup.3 He is spin-polarized. Spin-polarization of the .sup.3 He affects the cross section of the control volume for fission neturons and hence, the reactivity. An irradiation source is directed within the .sup.3 He for spin-polarizing the .sup.3 He. An alkali-metal vapor may be included with the .sup.3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with .sup.3 He to spin-polarize the .sup.3 He atoms.

Abstract: A nuclear excitation laser type intra-reactor neutron flux measuring system of this invention is comprised of a laser oscillator filled with a nuclear exciting gas such as .sup.3 He, KrF or XeF, mounted on the tip of a control rod. The nuclear exciting gas is made into a plasma by the neutrons or the fragments of fissioned nuclei when the tip is positioned in the reactor core by raising the control rod. Since the nuclear exciting gas made into a plasma itself generates a laser beam or amplifies a laser beam projected from the outside, the behavior of neutrons can be monitored in detail after guiding this light response to the light processing system located outside, distinguishing the energies of neutrons from the spectrum and calculating the density and the flux of the neutron in each energy. Furthermore, the detecting sensitivity can be enhanced by forming the responsive membrane made of U.sub.3 O.sub.8 and so on, on the laser oscillator.

Abstract: Apparatus is provided for generating energy in the form of laser radiation. A tokamak fusion reactor is provided for generating a long, or continuous, pulse of high-energy neutrons. The tokamak design provides a temperature and a magnetic field which is effective to generate a neutron flux of at least 10.sup.15 neutrons/cm.sup.2.s. A conversion medium receives neutrons from the tokamak and converts the high-energy neutrons to an energy source with an intensity and an energy effective to excite a preselected lasing medium. The energy source typically comprises fission fragments, alpha particles, and radiation from a fission event. A lasing medium is provided which is responsive to the energy source to generate a population inversion which is effective to support laser oscillations for generating output radiation.

Abstract: A laser using heat and thermionic electrical output from a nuclear reactor in which heat generated by the reactor is utilized to vaporize metal lasants. Voltage output from a thermionic converter is used to create an electric discharge in the metal vapors. In one embodiment the laser vapors are excited by a discharge only. The second embodiment utilizes fission coatings on the inside of heat pipes, in which fission fragment excitation and ionization is employed in addition to a discharge. Both embodiments provide efficient laser systems that are capable of many years of operation without servicing. Metal excimers are the most efficient electronic transition lasers known with output in the visible wavelengths. Use of metal excimers, in addition to their efficiency and wavelengths, allows utilization of reactor waste heat which plagues many nuclear pumped laser concepts.

Abstract: Methods and associated apparati for use of collisions of high energy atoms and ions of He, Ne or Ar with themselves or with high energy neutrons to produce short wavelength radiation (.lambda..apprxeq.840-1300 .ANG.) that may be utilized to produce cathode-anode currents or photovoltaic currents.