Abstract: Seed-blanket type nuclear reactor cores (10,100) are employed to burn thorium fuel with conventional reactor fuels, including nonproliferative enriched uranium, and weapons or reactor grade plutonium. In a first embodiment, the core (10) is completely nonproliferative in that neither the reactor fuel, nor the generated waste material, can be used to manufacture nuclear weapons. In a second embodiment of the invention, the core (100) is employed to burn large amounts of weapons grade plutonium with the thorium, and provides a convenient mechanism by which stockpiled weapons grade plutonium can be destroyed and converted into electrical energy. The cores of both embodiments are comprised of a plurality of seed-blanket units (12, 102) which have centrally located seed regions (18,104) that are surrounded by annular blanket regions (20,106). The seed regions contain the uranium or plutonium fuel rods (22,110), while the blanket regions contain thorium fuel rods (26,118).

Abstract: A method of producing austenite steel for use in the radiation zone of a nuclear reactor. The method comprising the steps of forming the austenite steel with about 17% by weight chromium, about 9 to 11.5% by weight nickel, about 0.04% by weight carbon, and iron impurities whose content of silicon is about 0.1% by weight and whose total content of sulfur and phosphorous is less than 0.03% by weight; and exposing the austenite steel to a temperature treatment at a temperature less than 1150 .degree. C. to produce a fine grain lattice with grain diameter features under approximately 20 .mu.m.

Abstract: A steady-state source of neutrons is produced within an electrically grounded and temperature controlled chamber confining tritium or deuterium plasma at a predetermined density to effect implantation of ions in the surface of a palladium target rod coated with diffusion barrier material and immersed in such plasma. The rod is enriched with a high concentration of deuterium atoms after a prolonged plasma ion implantation. Collision of the deuterium atoms in the target by impinging ions of the plasma initiates fusion reactions causing emission of neutrons during negative voltage pulses applied to the rod through a high power modulator. The neutrons are so generated at a relatively high dose rate under optimized process conditions.

Abstract: An apparatus, and method, are disclosed for producing a high specific activity of a radioisotope in a single increment of target material, or sequentially within in-series increments of target material, by exposing a targeted isotope in the target material to a high energy photon beam to isotopically convert the targeted isotope. In particular, this invention is used to produce a high specific activity of Mo.sup.99, of at least 1.0 Ci/gm or preferably at least about 10.0 Ci/gm, from Mol.sup.100.

Abstract: A fuel assembly for a boiling water reactor where the fuel assembly during operation is arranged vertically in the core of the reactor. The fuel assembly comprises a plurality of vertical fuel rods (22) arranged in one or more fuel bundles, wherein at least the majority of the fuel rods comprise a stack of fuel pellets (7) surrounded by a cladding tube (8b) and a plenum tube (23) which is connected to the upper part of the cladding tube (8b), the plenum tube having a cross-section area which is smaller than the cross-section area of the cladding tube.

Abstract: A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Abstract: An improved test for determining densification characteristics of nuclear fuel including a fissionable ceramic material is disclosed. The test includes controlling the testing atmosphere to impede loss through vaporization of silica and in turn density reduction due to compositional changes.

Abstract: A tubular blank (22) is rolled on a mandrel (14) in a pilgrim rolling mill. In a first rolling stage, a first part of the blank (22) is rolled on a first part (18,19) of the mandrel (14), with a reduction of the outside diameter of the blank (22) to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to one of a first wall thickness (e1) and a second wall thickness (e2) exceeding the first wall thickness (e1). The mandrel (14) is advanced in the axial direction. A second part of the blank (22) is rolled on a second part (20,21) of the mandrel spaced from the first part in the axial direction with a reduction of the outside diameter of the blank to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to the other of the first wall thickness (e1) and second wall thickness (e2).

Abstract: A neutron absorbing pin including at least, a neutron absorber, a thin-wall pipe surrounding the neutron absorber, and a cladding disposed at a distance from the thin-wall pipe. In the neutron absorbing pin, the difference between the coefficient of thermal expansion (.alpha.1) of the neutron absorber and the coefficient of thermal expansion (.alpha.2) of the thin-wall pipe has an absolute value of .vertline..alpha.2-.alpha.1.vertline..ltoreq.10.times.10.sup.-6 /K.

Abstract: A nuclear reactor includes a core melt collection chamber having walls with multilevel protective layers. The layers include one layer part made of refractory concrete and another layer part made of ceramic bricks. The protective layers are anchored to the structural concrete of the collection chamber. In order to provide structural simplification, the layer part made of refractory concrete is constructed in the form of prefabricated blocks which are jointed together and are fastened to the structural concrete, and the layer part made of ceramic bricks is braced to the blocks of the layer part made of refractory concrete.

Abstract: A depressurization system (1) for pressurized steam operated plant employing injection of cold water contained in a superelevated tank (5), said injection being triggered rapidly and in a manner independent of the magnitude of the damage and of the presence of incondensible gases, by means of a natural circulation of steam in a closed loop of pipes (19, 20, 21, 22) around said plant (2, 3, 4), caused by the condensation of steam in a condenser (10), placed on said pipes, during the occurence of an accident, comprises a first siphon-type hydraulic shutoff (32), on said pipe loop (19, 20, 21, 22) and arranged close to the inlet collector (14) of said condenser (10), a second siphon-type hydraulic shutoff (29), on the cold water delivery pipe (26) and placed close to the pressurized steam operated plant (2, 3, 4), said second siphon-type hydraulic shutoff (29) being below said first siphon-type hydraulic shutoff (32).

Abstract: Isotopic hydrogen enrichment in a soluble metal is achieved through temperature gradient effects by applying a heat source and a heat sink to two spaced regions of the metal within which isotopic hydrogen atoms are absorbed and enclosed by a diffusion-barrier material. The temperature gradient so created forces the atoms of hydrogen in the hot region to migrate into the cold region, resulting in higher isotopic hydrogen density in the cold region. Discharge of the absorbed isotopic hydrogen is prevented effectively by the diffusion-barrier material.

Abstract: In order to reduce the flow resistance of a coolant flowing through a passage in a support plate of a boiling water reactor and entering a transition piece at a lower end of a fuel assembly resting on the support plate, a lower rim of the transition piece forms a conically tapered surface which fits into a corresponding conical counter-surface at an upper edge of the passage. The lower rim of the transition piece forms a circular inlet which is concentric with the passage and has a size equal to or slightly larger than the passage. Fingers protruding laterally into the passage and extending down into the passage are used to center the lower rim within the passage. Additionally, end caps of the fuel rods may be stream-lined and the lower tie plate of the fuel assembly may be spaced apart from an inner surface of a fuel channel by a plurality of ribs which form a plurality of peripheral through holes on each of the four inner surfaces of the rectangular-shaped fuel channel.

Abstract: An in-vessel structure for a top-entry type fast reactor wherein a core is positioned in the interior of a reactor vessel, an upper core structure being provided above the core, a coolant passing through a cold leg piping inserted from an upper portion of the reactor vessel thereinto and reaching the core, in which the coolant is heated, the coolant then flowing out to an upper plenum, the resultant coolant passing through a hot leg piping, which is inserted from an upper portion of the reaction vessel thereinto, and reaching the outside of the reactor vessel. A plurality of annular fins are fixed horizontally in an axially spaced manner to both the portions of an outer circumferential surface of the upper core structure and the opposite portions of an inner circumferential surface of the reactor vessel, these portions being under the free liquid surface during a rated operation of the reactor.

Abstract: A method for packaging, compacting or storing spent control and absorber elements of light-water reactors for waste disposal, a device for preparing an elongated component of a spent control element, a light-water-cooled reactor and a coil of an originally elongated component are provided for storing absorber fingers or absorber sheets of spent control elements in storage containers in pressurized-water reactors or boiling-water reactors. The absorber fingers or absorber sheets are separated from the control elements. They are not cut into pieces (in which process large amounts of radioactive substances would be released), but instead they are only deformed, namely wound into coils which can be stacked in a space-saving manner in the storage containers.

Abstract: To provide a reactor core for light water cooled reactor, a fuel assembly and a control rod intended for Pu multi-recycling at a breeding ratio of about 1.0, or 1.0 or more while keeping the economical or safety performance to the same level as in BWR now under operation, that is, while minimizing the change for the incore structures and maintaining the void coefficient negative. A reactor core for a light water cooled reactor having an effective fuel-to-water volume ratio of 0.1 to 0.6 by the combination of a dense lattice fuel assembly constituted of fuel rods formed by adding Pu to degraded uranium, natural uranium, depleted uranium or low concentrated uranium, coolants at high void fraction of 45% to 70% and a cluster-type, Y-type or cruciform control rod.

Abstract: A zirconium alloy tube for forming the whole or the outer portion of a nuclear fuel pencil housing or a nuclear fuel assembly guide tube. The zirconium alloy contains 0.8-1.8 wt. % of niobium, 0.2-0.6 wt. % of tin and 0.02-0.4 wt. % of iron, and has a carbon content of 30-180 ppm, a silicon content of 10-120 ppm and an oxygen content of 600-1800 ppm. The tube may be used when recrystallized or stress relieved.

Abstract: A process for improving packaging efficiency uses three dimensional, computer simulated models with various optimization algorithms to determine the optimal segmentation process and packaging configurations based on constraints including container limitations. The present invention is applied to a process for decontaminating, decommissioning (D&D), and remediating a nuclear facility involving the segmentation and packaging of contaminated items in waste containers in order to minimize the number of cuts, maximize packaging density, and reduce worker radiation exposure. A three-dimensional, computer simulated, facility model of the contaminated items are created. The contaminated items are differentiated. The optimal location, orientation and sequence of the segmentation and packaging of the contaminated items is determined using the simulated model, the algorithms, and various constraints including container limitations. The cut locations and orientations are transposed to the simulated model.

Abstract: An affordable means of protecting a barn against fly infestation by trapping in a novel trap design predatory arthropods such as Carcinops pumilio and Macrocheles muscaedomesticae from another barn having a mature predator population, and transferring the traps to accumulations of manure which are underpopulated with the predatory arthropods. The predators self-release onto the predator-free manure and establish themselves, preventing fly infestations which would normally occur. The trap of the invention is a box-like structure, having a filter surface on one side which has openings large enough to admit Hister beetles and Macrochelid mites, but small enough to prevent the entry of hide beetles and litter beetle pests. Inside the box is an appropriate bait material which will attract the desired predatory beetles or mites, such as a slurry of housefly eggs in water spread on absorbent material. The traps are spread across a mature manure pile.

Abstract: A method and apparatus for transporting a positive ion beam to a distant target. An ion channel is created as a path to the target, and the beam injected into the channel at a mildly-relativistic beam velocity. Because the beam is mildly-relativistic, the electric field caused by its positive charge propagates well in advance of the beam, attracting free electrons in the plasma channel and pulling them into the beam along its axis of propagation. The current which is initiated by this precursor electron flow, is sustained during the duration of the beam, and is then a combination of the beam current and additional current carried by the electrons within the channel. As a result, a magnetic flux circulates annularly about the beam of a sufficient magnitude to pinch the beam.