Abstract: An improved nuclear reactor wherein the bolted connections between the baffle plates and baffle former and the baffle former and the core barrel are provided with a noval locking device that prevents loosening of the bolted connections. The locking device to prevent loosening of bolted connections where a threaded bolt is used to secure two components together uses a threaded lock nut over the bolt head, cooperative with a threaded wall in a recess in a component. The lock nut and wall of the recess have threads opposite the threads of the bolt. Deformable sections are formed in the base of the lock nut to engage an unsymmetrical cavity in the head of the bolt. Turning of the bolt in a direction that would tend to loosen the connection causes tightening of the lock nut. The wall of the lock nut may be threadedly engaged with the wall of the recess or the lock nut wall may have slits formed thereon which enable deformation of wall portions to engage the threaded wall of the recess.

Abstract: Plasma including plasma ions is magnetically confined by a magnetic field. The plasma has a defined outer surface and is intersected by resonance surfaces of respective common ion cyclotron frequency of a predetermined species of plasma ions moving in the magnetic field. A radio frequency source provides radio frequency power at a radio frequency corresponding to the ion cyclotron frequency of the predetermined species of plasma ions moving in the field at a respective said resonance surface.

Abstract: Apparatus comprising a seal connector is disclosed for sealingly connecting flow channels in the core support plate with flow channels in fuel assemblies for use in a spectral shift pressurized water nuclear reactor. Spectral shift is obtained by displacing a portion of the light water in the core with deuterium oxide or a combination of deuterium oxide and light water or various gases such as helium during the initial state of reactor operation to harden the nuclear spectrum and thereby reduce excess reactivity and increase the production of fissile materials. The seal connectors provide a sealed flow channel for introducing the deuterium oxide into the core during the early stages of reactor operation and for reintroducing the light water into the core during the later stages of reactor operation.

Abstract: A closure for an inclined duct having an open upper end and defining downwardly extending passageway. The closure includes a cap for sealing engagement with the open upper end of the duct. Associated with the cap are an array of vertically aligned plug members, each of which has a cross-sectional area substantially conforming to the cross-sectional area of the passageway at least adjacent the upper end of the passageway. The plug members are interconnected in a manner to provide for free movement only in the plane in which the duct is inclined. The uppermost plug member is attached to the cap means and the cap means is in turn connected to a hoist means which is located directly over the open end of the duct.

Abstract: Fast neutron nuclear reactor of the type comprising a primary circuit integrated into a liquid metal-filled vessel and containing the reactor core, as well as means for circulating the said liquid metal and means for transferring the heat carried by the liquid metal to the water circulating in a water/steam circuit, wherein the heat transfer means comprise at least one steam generator located in the reactor vessel and having at least one group of inner tubes in which circulates the water of the water/steam circuit, at least one group of outer tubes immersed in the primary liquid metal, the outer tube surrounding each of the inner tubes in order to define therewith an annular space under a neutral gas pressure, connected to secondary circuit with a low thermal power having means for circulating this pressurized neutral gas, such as helium in said annular space and ensure the heat exchange.

Abstract: A nuclear fuel element comprising an elongate block of refractory material having a generally regular polygonal cross section. The block includes parallel, spaced, first and second end surfaces. The first end surface has a peripheral sealing flange formed thereon while the second end surface has a peripheral sealing recess sized to receive the flange. A plurality of longitudinal first coolant passages are positioned inwardly of the flange and recess. Elongate fuel holes are separate from the coolant passages and disposed inwardly of the flange and the recess. The block is further provided with a plurality of peripheral second coolant passages in general alignment with the flange and the recess for flowing coolant. The block also includes two bypasses for each second passage.

Abstract: A clamp is applied to a thermocouple of a nuclear reactor vessel at a location above the level of the vessel head, the clamp being supported on a chain or cable block which is coupled through a load cell to an overhead crane. A vibrator is mounted on the clamp. The thermocouple is withdrawn by pulling it longitudinally upwardly with a predetermined force and, if it does not move, vibrating it by applying vibratory energy at an angle of about 20.degree. of its longitudinal axis of the thermocouple. The pulling force is then periodically increased by 45-kg increments until longitudinal movement of the thermocouple begins.

Abstract: A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material.

Abstract: An improved grid structure is provided for a nuclear reactor fuel assembly whose sole purpose is to promote a crossflow mixing of the coolant through the fuel assembly rather than the support of the fuel rods. The grid straps form an egg-crate configuration creating cell openings for receiving the fuel rods. Associated with each cell opening is at least one coolant flow mixing vane that projects over the cell opening and four dimple protrusions which are open to the flow of coolant therethrough. The dimple protrusions extend into the cell opening to a further extent than the mixing vane so as to prevent damaging impact of the fuel rod with a vane upon transverse movement of the fuel rod across the cell opening. In reducing the pressure drop of the coolant flow through the assembly, the height of the inner grid straps is substantially less than the height of the outer border strap.

Abstract: The invention concerns a steam generator heated by the cooling gas of a nuclear reactor and arranged in the reactor pressure vessel within a vertical shaft. A blower associated with the steam generator is installed above it. The hot gas is conducted to the steam generator in the form of a helical bundle in the downward direction, with the hot gas being conducted initially downward through an annular channel and entering the bundle of heat exchanger tubes at a uniform velocity. The annular channel is sealed in upward direction by means of a sliding seal, which also serves as an earthquake support. In order to provide access to the feed water and live steam lines in view of the blower arranged on top, the two lines are conducted laterally out of and through the reactor pressure vessel. By means of the special fixation of the individual tubes of the heat exchanger bundle in vertical plates and the presence of an expansion zone for the recycling pipes, differential thermal expansion may be kept small.

Abstract: An emergency transfer tube closure for a nuclear reactor well comprising an elongated, vertically-extending, U-shaped guide laterally disposed on each side of the transfer tube, a closure plate vertically disposed between the guides having rollers thereon riding within the guides permitting movement of the closure plate downwardly into sealing engagement with the transfer tube under emergency conditions.

Abstract: A boiling water reactor has a plurality of control rods disposed in the reactor and adapted to be driven independently by corresponding control rod driving mechanisms, each of the control rod driving mechanisms having a hydraulic piston adapted to be actuated by pressurized water supplied thereto through a hydraulic unit annexed to each control rod driving mechanism to drive the associated control rod into and out of the reactor core. The boiling water reactor has a system for controlling the driving water for the control rod driving mechanisms. The control rod driving water control system has a control rod driving water control unit which controls the direction and velocity of movement of the hydraulic pistons. The control rod driving water control unit is used commonly for a plurality of control rod driving mechanisms.

Abstract: A support system for connection to an outer surface of a J-shaped steam generator for use with a nuclear reactor or other liquid metal cooled power source. The J-shaped steam generator is mounted with the bent portion at the bottom. An arrangement of elongated rod members provides both horizontal and vertical support for the steam generator. The rod members are interconnected to the steam generator assembly and a support structure in a manner which provides for thermal distortion of the steam generator without the transfer of bending moments to the support structure and in a like manner substantially minimizes forces being transferred between the support structure and the steam generator as a result of seismic disturbances.

Abstract: A liquid metal cooled fast breeder reactor which permits a closer installation of a fuel handling mechanism relative to an upper reactor core structure of the reactor. The fuel handling mechanism has a fuel handling body without a housing, and has a rotational driving device on a rotating plug of a shield plug device of a reactor vessel. The fuel handling mechanism has an aseismatic support extending outwardly from the upper reactor core structure. The fuel handling mechanism is supported, at its upper portion, by the rotational driving device, and secured, at its lower protion, by the aseismatic support.

Abstract: A reconstitutable fuel assembly includes an improved attaching structure which has a plurality of coupling sleeves interfitting the upper hold-down plate, lower adapter plate and a plurality of hold-down springs of the top nozzle of the assembly. The coupling sleeves insert over a plurality of extensions extending upwardly from the main bodies of the guide thimbles. The sleeves rest on annular ledges formed on the bottom portions of the respective extensions. A removable cap is attached to the top portion of each of the thimbles extensions and applied to the upper portion of each of the coupling sleeves to releasably lock the coupling sleeves on the guide thimble extensions. In view that the coupling sleeves are fixed to the adapter plate at their lower portions, the sleeves and hold-down plate, adapter plate and hold-down springs disposed between the plates and encircling individual sleeves can be removed together from the fuel assembly as a unitary subassembly upon removal of the removable caps.

Abstract: Steam generator, particularly for a pressurized water nuclear reactor, which has in per se known manner a water box in which circulates the hot water from the reactor core, and then enters a series of heat exchange tubes installed in a tube plate and extending within a secondary ferrule traversed by the secondary water, wherein the water box, secondary ferrule and tube plate are three independent, disassemblable assemblies.

Abstract: A tumorous patient is injected with a compound including an element that accumulates in tumors and that has an isotope which emits an alpha particle in a neutron capture reaction. The patient is positioned in front of a radiation beam that has been filtered to remove most neutrons having energies above 30 KeV and most thermal neutrons, leaving predominantly epithermal neutrons which are moderated to a thermal level by outer layers of tissue and are captured by the incorporated isotope.A radiation beam having neutrons with a wide distribution of energies is filtered with aluminum, sulfur and argon filters, whose cross sections complement each other in providing a beam with energies predominantly in the epithermal range. The filter mass attenuates the gamma radiation. Beams with lower ratios of undesirable gamma radiation to epithermal beam intensity can be attained with filter combinations which include liquid argon. A poor geometry filter of bismuth or lead can also improve the gamma to neutron ratio.

Abstract: A graphite roof reflector for a small, high temperature reactor is arranged under the hot gas collector space and is therefore exposed to high thermal and radiation loads. In order to make possible the satisfactory support over the entire operating life of the reactor, the roof reflector is assembled from a center part and an annular part, which are supported in a different manner. The annular part is supported on the side reflector of the reactor. The center part is suspended by means of tie rods from a cover located over the hot gas collector space. The tie rods are placed into bores of the cover through which cold gas flows.

Abstract: A nuclear reactor has a stationary horizontal core plate and a plurality of upright nuclear fuel assemblies all having the same cross-section and located side by side in a regular polygonal network. Each fuel assembly either has two locations for elongated plug elements or is adjacent a fuel assembly having such locations. A device for holding down the fuel assemblies comprises a plurality of locking sets each having at least one deformable locking member and a rigid member one of which is carried by a fuel assembly and the other by the core plate. The deformable locking member is so located with respect to a location and with the associated rigid member that insertion of an elongated element into the location forces the deformable locking member into positive engagement with the associated rigid member.

Abstract: A thermal barrier/core support for the fuel core of a nuclear reactor having a metallic cylinder secured to the reactor vessel liner and surrounded by fibrous insulation material. A top cap is secured to the upper end of the metallic cylinder that locates and orients a cover block and post seat. Under normal operating conditions, the metallic cylinder supports the entire load exerted by its associated fuel core post. Disposed within the metallic cylinder is a column of ceramic material, the height of which is less than that of the metallic cylinder, and thus is not normally load bearing. In the event of a temperature excursion beyond the design limits of the metallic cylinder and resulting in deformation of the cylinder, the ceramic column will abut the top cap to support the fuel core post.