Abstract: A technique for determining percent body fat using neutron inelastic scattering is disclosed. It relies on a correlation between a carbon-oxygen ratio in the body and the percent body fat with corrections made for a level of patient hydration in the lean tissue. The animal body is irradiated with neutrons having sufficient energy to inelastically scatter off carbon and oxygen. The resulting gamma rays are detected and counted, and the level of hydration is measured. The ratio of the detected gamma rays and hydration are then related to a proportion of fat in the animal body. This technique provides accuracy approaching that achieved with hydrodensitometry with only small radiation doses between 5 and 20 millirem, but without any requirements for immersion.

Abstract: In an in-core fixed nuclear instrumentation system for a reactor, each of a plurality of in-core nuclear instrumentation assemblies has a nuclear instrumentation tube. LPRM detectors are housed in the nuclear instrumentation tube for detecting LPRM signal in a core of the reactor. A GT assembly is housed in the tube. The GT assembly has fixed GT detectors for detecting &ggr;-ray heating values and a built-in heater therein for calibrating the fixed GT detectors. The fixed GT detectors are arranged at least close to the fixed LPRM detectors, respectively. GT signals by the detected &ggr;-ray heating values of the fixed GT detectors of each GT assemblies are processed by a GT signal processing unit. The heater in each GT assemblies is electrically energized by a GT heater control unit. Predetermined time intervals are stored in a memory unit.

Abstract: A new spring design for a strap employed in a grid of a nuclear reactor fuel assembly includes a pair of ligaments that each connect with the free portion of the retention plate. The ligaments each are equally spaced a certain distant from the termination of the slots within the strap body. The spring additionally includes a spring contact plate that is wider than the connections of the spring ligaments with the free portion to increase the surface area with which the spring contact plate is in contact with and retains the fuel rod, and thus reduces the contact stresses therebetween. The spring contact plate additionally includes an embossed spring contact member protruding outwardly therefrom reduces the frictional stresses on the fuel rod when it is inserted into and removed from the cell and during vibration of the fuel rod and/or the strap.

Abstract: A guide assembly is seated at the upper end of a channel for a nuclear fuel bundle. The guide assembly includes a lower guide plate with an opening corresponding in dimension to the dimension of the spacers of the fuel bundle to be inserted. The lower guide plate mounts depending locators to locate the guide apparatus on the channel. An upper guide plate spaced above the lower guide plate mounts rollers spaced from the lower guide plate a distance corresponding to the distance between the first and second spacers of the fuel bundle. The fuel bundle is lowered through the guide apparatus by engagement of the spacers with the rollers and in the channel opening to ensure the fuel bundle is guided into the channel without damage to either.

Abstract: A resistance member (e.g., fuel holding portion of the lower tie plate) is provided at the lower end of the fuel assembly. Provision is made of a coolant ascending path in which said water rods have coolant inlet ports that are open in a region lower than the resistance member to upwardly guide the coolant, and a coolant descending path which has a coolant delivery port that is open in a region higher than the resistance member to downwardly guide the coolant. The coolant ascending path and the coolant descending path are communicated with each other at their upper end portions.

Abstract: A nuclear fuel spacer grid, fabricated by intersecting a plurality of grid strips and used for placing and supporting a plurality of elongated fuel rods within a nuclear fuel assembly, is disclosed. The spacer grid of this invention has a plurality of dimple vanes on its grid strips. The dimple vanes are designed to guide the coolant from one cell to neighboring cells of the spacer grid, thus accomplishing a desired coolant mixing effect and increasing the thermal allowance of the fuel rods and accomplishing a high performance fuel assembly. The spacer grid also has a multi-spring structure, consist in of one arc-shaped main spring and two bow-shaped sub-springs. The main spring directly supports the fuel rod within the spacer grid, while the sub-springs have the same radius of curvature as that of the external surface of the fuel rod and effectively support the fuel rod when the main spring fails to support the fuel rod.

Abstract: In a plasma facing member exposed to a plasma beam of nuclear fusion reactors or the like, such as an electron beam, a tungsten layer is formed by the use of a CVD method and has a thickness of 500 micron meters or more. The tungsten layer may be overlaid on a substrate of molybdenum or tungsten and comprises included gases reduced to 2 ppm or less and impurities reduced to 2 ppm or less. The tungsten layer is specified by either a fine equi-axed grain structure or a columnar grain structure. Alternatively, the material of the substrate may be, for example, Cu alloy, stainless steel, Nb alloy, or V alloy.

Abstract: A thin foil stripper and simple non-obstructing power meter for a space based neutral particle beam system consisting of a panel of thin foils supported by resistance wires and mounted on a wheel or disk in such a manner that the surface used for stripping the beam may be changed or replaced periodically. The power meter consists of four resistors arranged in the form of a bridge, a power source (battery), a detector (voltmeter), and a display unit (recorded, etc.). Two of the resistors consist of the wires which support the foils and are nearly identical. The other two resistors are used to balance the bridge. When one of the strippers is exposed to the neutral particle beam, the support wire is heated, the resistance changes, and the bridge becomes unbalanced. The magnitude of the voltage produced is proportional to the power in the beam. The power meter is non-obstructing.

Abstract: In a nuclear reactor core, control blades form discrete control blade groups forming a core pattern including first and second main groups, respectively, symmetrically and asymmetrically arranged about the core. Each main group has first and second sub-groups, each sub-group at each control blade location within the core being located alternately in orthogonally-related X and Y directions in plan view of the core. The first sub-group of the first main group includes an operational sub-group. The blades of the first and second main groups are used simultaneously. The blades of the second main group are used only as shallow blades. The blades of the first main group are movable into deep or shallow positions from withdrawn positions. Each fuel bundle operates without an adjacent control blade for a time period twice as long as any previous period of operation with an adjacent control blade inserted into the core. Any one control blade is fully withdrawn for two consecutive periods after insertion.

Abstract: A transport/storage container for spent nuclear-fuel elements has a vessel having a side wall with an inner surface defining an interior extending along an axis and a plurality of like basket sections forming a stack extending substantially a full axial length of the interior and forming a plurality of axial full-length rectangular-section wells adapted to receive the spent fuel elements. Each of the basket sections is formed of two long light-metal neutron-absorbing plates crossing each other, each having a pair of outer ends directly engaging the inner surface of the side wall in heat-transmitting contact therewith, and subdividing the interior at the respective section into a plurality of segments. A plurality of short light-metal neutron absorbing plates are fitted together in each of the segments and form with the main plates of the respective section rectangular-section axially throughgoing openings forming the wells with the plates of the other sections.

Abstract: Combination primary containment cooling system and residual heat removal steam condensers (PCCS-CND) operable in a containment cooling mode and in a reactor vessel cooling mode are described. In the containment cooling mode, the PCCS-CND interfaces with the primary containment vessel (PCV) through an isolation valve which can be normally closed or open. In the normally closed valve position, and upon receipt of a high drywell pressure signal, the valve opens allowing the steam in the PCV to flow to the PCCS-CND where it condenses, and the decay heat is transferred to the condenser pool. In the normally open valve position, the PCCS-CND is in the standby containment cooling mode of operation. In the reactor pressure vessel (RPV) cooling mode, the PCCS-CND interfaces with the RPV through isolation valves.

Abstract: A fuel assembly spacer grid including swirl deflectors respectively arranged at interconnections between interconnecting longitudinally and laterally-extending straps on upper ends of the interconnecting straps adapted to support fuel elements of a nuclear fuel assembly. Each of the swirl deflectors has four vanes bent to have an air vane shape. By virtue of this configuration, an improvement in the efficiency of the spacer grid cooling the fuel elements. The spacer grid also includes springs each configured to generate not only a main spring force caused by a displacement of the spring occurring when the spring comes into contact with a fuel element placed in a reactor core, but also an additional spring force caused by hydraulic pressure applied to the spring. Each spring, which is in a fixed state at one end thereof, has a free bent portion at the other end.

Abstract: A new transmutation assembly permits an efficient transmutation of a long-lived radioactive material (long-lived FP nuclides such as technetium-99 or iodine-129) which was produced in the nuclear reactor. Wire-type members of a long-lived radioactive material comprised of metals, alloys or compounds including long-lived FP nuclides are surrounded by a moderator material and installed in cladding tubes to form FP pins. The FP pins, and nothing else, are housed in a wrapper tube to form a transmutation assembly. The wire-type members can be replaced by thin ring-type members. The transmutation assemblies can be selectively and at least partly loaded into a core region, a blanket region or a shield region of a reactor core in a fast reactor. From a viewpoint of reducing the influence on the reactor core characteristics, it is optimal to load the transmutation assemblies into the blanket region.

Abstract: A water rod for a fuel assembly of a boiling water nuclear reactor has a first end and a second end, wherein at least one of the first and second ends is directly attachable to a tie plate of the fuel assembly without an end plug. The structure of the present invention simplifies the manufacturing process and reduces the cost of the fuel assembly in the boiling water nuclear reactor. The water rod according to the invention has one or both of its ends configured to be directly attachable to the tie plate of the fuel assembly.

Abstract: A hermaphroditic absorber exploits the inherent spatial change in the neutron spectrum within a lumped poison mass in a thermal reactor neutron flux field. The hermaphroditic absorber (poison mass) incorporates two types of absorbers, the first being a strong thermal absorber near the surface of the mass, and the second being a strong resonant absorber in the interior of the poison mass. The outer regions of the poison mass are comprised of a strong “1/v” thermal absorber, and the inner region of the poison mass is comprised of a resonance absorber. This resonance absorber more appropriately exploits the hardened characteristics of the neutron spectrum within the absorber mass by selectively absorbing the epi-thermal neutrons. The creation of the hermaphroditic poison mass permits an increase in the control material worth while maintaining the external dimension of the structure containing the control material, such as a BWR control rod.

Abstract: A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Abstract: A method of jacketing a uranium slug to an aluminum container comprising applying a coating to the exterior of the container, the coating consisting of colloidal graphite in water, permitting the coating to dry, applying an alloy of aluminum and silicon to the interior surface of the container at a temperature between 588° C. and 594° C., inserting the slug into the container in complete contact with the alloy, and quenching the assembly.

Abstract: A method for providing a leak-tight metal enclosure to a fuel matrix penetrated by coolant channels, wherein the mutually contacting surfaces of said metal enclosure and said fuel matrix are metallurgically bonded, comprising placing a metal cladding about the lateral surface of said fuel matrix; disposing metal coolant tubes within said coolant channels; placing a perforated header plate having tubular extensions at each end of the fuel matrix from which the coolant tube ends protrude, said coolant tubes passing through said perforated header plate and said tubular extensions and terminating even with the ends of said extensions; welding, under vacuum, said cladding to said header plates, and the ends of said coolant tubes to the ends of said tubular extensions; exposing the assembly comprising the fuel matrix and enclosure to a gas at high temperature and pressure; and machining said header plates to provide a finished fuel element.

Abstract: A T-box assembly to facilitate attaching a core spray line to a reactor core spray nozzle safe end without welding is described. In one embodiment, the T-box assembly includes a T-box housing, a cruciform wedge, and a draw bolt. The T-box housing is configured to be positioned so that a first end is located inside a core spray nozzle and engages the core spray nozzle safe end. Two other ends are configured to be in substantial alignment and configured to couple to core spray line header pipes. The T-box housing also includes a cover opening configured to receive a T-box cover plate. The T-box cover plate includes a draw bolt opening configured to receive the draw bolt. The first end of the T-box also includes a plurality of positioning lugs configured to engage the core spray nozzle to center the T-box housing in the nozzle bore. The cruciform wedge includes four web members extending from a central member and configured so as to form an X shaped configuration.

Abstract: A method of jacketing a body of fissionable material within a nonfissionable jacket having a cup-shaped body open at one end and a cap effecting closure at said end comprising the steps of inserting the cup-shaped body into a tightly fitting cup-shaped sleeve; completely submerging said assembly in a bonding bath of a molten metallic bonding material, allowing the inner body to fill with molten bonding material; dipping the fissionable body into the open end of said assembly while under the surface of the bonding bath; closing the open end of the assembly with the cap while under the surface of the bonding bath; removing the complete assembly from the bonding bath; quenching in cold water; and removing the sleeve.