Abstract: A nuclear reactor comprising a reactor vessel, a core housed in the reactor vessel, an ultrasonic transducer mounted in the vicinity of the upper end of the core for emitting and receiving an ultrasonic wave pulse signal propagating above the core, means for rotating the transducer by a prescribed angle to scan horizontally the ultrasonic wave emitted from the transducer, a plurality of reflective means mounted in the vicinity of the upper end of the core in a manner to face the transducer for reflecting the ultrasonic wave signal emitted from the transducer, means for energizing the transducer, and means for displaying the ultrasonic wave signal reflected by the reflective members and received by the transducer in synchronism with the wave scanning motion of the transducer, wherein each reflective member comprises reflective surfaces each capable of reflecting the incident ultrasonic wave signal in a direction parallel with the incident direction and is mounted such that the distances of the reflective surfa

Abstract: A method and an apparatus for controlling feedwater flow to a steam generating device in a tripped condition of the steam generating device are disclosed.

Abstract: Apparatus is disclosed for inertial fusion in which a pulse of ions is injected into a magnetic mirror where the ions are trapped in the form of an ion ring which is then magnetically compressed to increase its energy and reduce its dimensions. The compressed ion ring is then accelerated through a guide tube to strike a pellet in a thermonuclear fusion reactor.

Abstract: The invention concerns a roof reflector suspended from the thermal cover shield of a gas-cooled pebble-bed reactor with a plurality of passages for absorber rods arranged in a triangular lattice, and with channels for the passage of the cooling gas. The roof reflector comprises a plurality of essentially hexagonal graphite blocks arranged in several layers to form vertical, closely-adjacent columns. A process for the disassembly of the roof reflector is further provided.

Abstract: A multi-sensor radiation detection system for removable insertion into a nuclear reactor wherein one conductor of all the sensors is a single, common element. This single common element is contained within a tubular metallic sheath and in cross-section comprises a multiple radial armed metallic conductor having a star shaped cross-section dimensioned to form wedge-shaped compartments throughout the active radiation detecting length of the metallic sheath.

Abstract: A strong focusing megatron has a hollow toroidal chamber in which a plasma of isotopes of hydrogen support an orbital current driven by a changing magnetic field whose amplitude is controllably variable and whose direction is generally coaxial with the major axis (z-axis) of the toroidal chamber while the current is stabilized by a strong focusing magnetic field of alternately focusing and defocusing sections whose field is generally in the region of the toroidal chamber.

Abstract: In apparatus for exchanging a control rod drive mechanism of a nuclear reactor of the type comprising a horizontal platform supported to be rotatable in a working chamber disposed below a reactor pressure vessel and a traveling carriage traveling on a rail assembly laid on the platform, there is provided a beam attached to the traveling carriage to be swingable between the vertical and horizontal positions and provided with a carrier for vertically moving the control rod drive mechanism. A holding device is secured to the beam so as to hold the control rod drive mechanism when the beam is moved to the horizontal position. The bolts which are used to connect the control rod drive mechanism to a housing in the pressure vessel are loosened and clamped by a bolt mounting device, which is conveyed in and out of the passage of movement of the carrier.

Abstract: A submerged ultrasonic viewer for use in a liquid metal cooled fast reactor vessel to detect floated reactor core components. The viewer, which includes an ultrasonic transducer, a transducer scanning drive mechanism and a related electrical control circuit, an image display circuit, and a reflecting surface, i.e. a handling head of a core element or a reflecting plate, is improved to enhance image accuracy by providing the reflecting surface with at least one continuously curved surface having a convex or a concave contour, or plural continuously curved surfaces with concave and convex contours.

Abstract: A self-powered neutron and gamma-ray flux detector is provided wherein the emitter comprises an emitter core of at least one material selected from nickel, iron, titanium and alloys based on these metals, and an emitter outer layer around the core which has a thickness in the range of the order of 0.03 mm to of the order of 0.062 mm and which is of at least one material selected from platinum, tantalum, osmium, molybdenum and cerium. With this construction, by increasing the emitter diameter beyond the optimum for a solid platinum emitter, the ratio of neutron to gamma-ray sensitivity, and hence the prompt response fraction, is increased while an acceptably small burnup rate is maintained. Larger diameter emitters of this construction have response characteristics that closely match those required for a fuel power detector in, for example, heavy-water-moderated, natural-uranium power reactors. The emitter core is preferably of Inconel (Trademark) and the emitter jacket is preferably of platinum.

Abstract: System for preventing erroneous operation of control rods for securing a safety control of a nuclear reactor. The erroneous operation preventing system is comprised of a control rod objective position setting means for setting an objective position of a control rod, a control rod position detector for detecting a position of the control rod, and an operation means which operates a difference between the objective position set up and the detected position of the control rod being operated and produces a signal for blocking the control rod operation when the control rod is operated so that the difference goes away from zero. The erroneous operation blocking system stops the control rod at the first possible control rod stopping position. The erroneous operation preventing system includes a return operation commanding unit for compensating for erroneous operation of the control rod when the control rod is erroneously operated.

Abstract: Shut-off device for a double-wall steam line extending out of a safety vessel of a pressurized water reactor includes a shut-off valve having a casing, the casing being directly connected to an end of a lead-through for the double-wall steam line, the casing being formed with steam inlet and outlet openings and with a further opening, and at least one of a safety and an exhaust gate valve having a casing, the last-mentioned casing being directly connected to the further opening.

Abstract: Earthquake-proof mounting support for control rod drives of nuclear reactors having a generally cylindrical reactor pressure vessel formed with a convex wall at least at one end thereof and including control rods with control rod drive shafts coupled thereto and mounted so as to be movable in axial direction thereof within tubular drive housings extending pressure-tightly through the end convex wall and sealed against the outside, the tubular drive housings comprising tube member forming respective feed-through passageways for the control rod drive shafts, the tube members having respective portions thereof extending with respectively varying lengths outside and beyond the convex wall to a given horizontal plane, and a support grid formed of a plurality of grid bars articulatingly connecting the tube members at respective free ends thereof outside the convex wall, respectively, to one another.

Abstract: A superconducting coil, suitable for generating a magnetic field within a nuclear reactor, wherein a structurally continuous disk helix is utilized to carry a plurality of parallel superconductor windings thereon. The structure provides an improved support to the superconductor windings to more positively prevent stresses or small movements that would cause the superconductor to go normal.

Abstract: There is provided a nuclear reactor count-factor-increase time monitoring circuit which includes a pulse-type neutron detector, and means for counting the number of detected pulses during specific time periods. Counts are compared and the comparison is utilized to develop a reactor scram signal, if necessary.

Abstract: Nuclear reactor installation having a tight concrete tank sunk at least in part into earth formed with a groundwater-permeable layer and a largely impermeable layer providing a lower boundary for the groundwater-permeable layer, includes a wall disposed in the earth and surrounding the concrete tank, the wall extending down through the groundwater-permeable layer at least to the impermeable layer, and means including a pump and a filter for separating activity carriers for connecting the part of the groundwater-permeable layer enclosed by the wall with the part of the groundwater-permeable layer located outside the wall.

Abstract: Methods and apparatus for merging of tokamak plasmas, having applications including pseudo steady-state tokamak operation, refueling, impurity removal and plasma heating. In such systems, currents of two merging tokamak plasmas are provided in the same direction so that the plasma columns attract each other, and the merging of the plasmas is carried out under the control of appropriate guiding fields.

Abstract: A device and method for relativistic electron beam heating of a high density plasma in a small localized region. A relativistic electron beam generator produces a high voltage electron beam which propagates along a vacuum drift tube and is modulated to initiate electron bunching within the beam. The beam is then directed through a low density gas chamber which provides isolation between the vacuum modulator and the relativistic electron beam target. The relativistic beam is then applied to a high density target plasma which typically comprises DT, DD, hydrogen boron or similar thermonuclear gas at a density of 10.sup.17 to 10.sup.20 electrons per cubic centimeter. The target plasma is ionized prior to application of the electron beam by means of a laser or other preionization source. Utilizing a relativistic electron beam with an individual particle energy exceeding 3 MeV, classical scattering by relativistic electrons passing through isolation foils is negligible.

Abstract: The present invention relates to an inertial device to permit and to prevent motion between two members, for example, the tubing and the body of a central reactor in a thermal or nuclear power station.

Abstract: There is provided a fluidized bed reactor for working up carbon coated particles, particularly nuclear fuel particles or fertile material particles consisting essentially of a cylindrical portion connected to a conical portion, there being provided gas supply pipes, gas distribution space and gas distribution heads within the conical reactor lower portion, the gas distribution members being arranged in at least two superimposed planes and distributed symmetrically over the cross-section of the reactor.

Abstract: A nuclear reactor flux mapping system having a plurality of neutron detectors operable to be driven into and out of a reactor core along any one of a number of pre-established paths. The detectors, corresponding drives (22) and drive controllers (28) are arranged into at least two physically separate and functionally independent channels. Each channel is respectively arranged to scan complementary paths through the core during normal system operation. At least two, redundant, functionally independent and physically separate "command end of processing" channels (31 and 33) are provided. Each of the command and processing channels (30) are independently operable to automatically, programmably sequence the detector scans and process the detector output data on all of the detector channels while being electrically buffered from each detector channel through two-ported memories (36) in a manner to prevent faults on any of the channels from disabling any of the other system channels.