Abstract: In order to facilitate refueling operations, cables, which provide control and power linkages between control element drive mechanisms (CEDMS), and a terminal panel supported on a side wall of the reactor cavity, are disposed in a cylindrical extension of a cylindrical enclosure which encloses the CEDMS, with sufficient slack that they can be drawn out of the cylindrical extension through windows and supported on a drawbridge type of arrangement comprised of pivotal window tray type structures which are respectively hingedly connected to the cylindrical extension and either the wall or the terminal panel, and which span the gap between the cylindrical extension and the terminal panel when pivoted to their respective supporting positions.

Abstract: A natural circulation reactor, especially a boiling water reactor, includes a reactor pressure vessel, a reactor core and a core jacket disposed within the reactor pressure vessel, surrounding the reactor core and having at least one inlet port and one outlet port for core coolant. A flow path for the core coolant, which is formed between the core jacket and the reactor pressure vessel, leads through the inlet port into the core jacket and has a flow cross section. At least one throttle element is disposed in the flow path for varying the flow cross section in order to regulate the core coolant flow rate. The flow cross section can be both increased and reduced in size by varying the cross sectional area of the throttle element, so that a regulation of the power of the natural circulation reactor is carried out in a simple way and, in an incident, a reduction in power to approximately 40% of the instantaneous reactor power is ensured.

Abstract: A method for producing energy from a nuclear fuel material contained in an enclosure, through a process of breeding of a fissile element from a fertile element of the fuel material via a .beta.-precursor of the fissile element and fission of the fissile element. A high energy particle beam is directed into the enclosure for interacting with heavy nuclei contained in the enclosure so as to produce high energy spallation neutrons. The neutrons thereby produced are multiplied in steady sub-critical conditions by the breeding and fission process. The breeding and fission process is carried out inside the enclosure.

Abstract: The device (15) for joining together a first plate (7) and a second plate (8)of the baffle assembly, which are located substantially at right angles, includes a screw (16) engaged in a housing consisting of an opening (18) passing through the first plate (7), and of a tapped blind opening (20) in the second plate (8). At least one opening (21) places an annular space (18b) around the shank (16b) of the screw in communication with the entry part (18a) of the opening (18) passing through the first plate (7), in order to deconfine the screw (16). The opening (21) may be a radial opening passing through a cup (17) against which the screw head (16a) comes to bear or an opening machined in the first plate (7) against a shoulder (18c) of the screw housing and the part (18b) of the opening for passing through the first plate (7) in which the shank (16b) of the screw (16) is engaged.

Abstract: A nuclear fuel rod for a pressurized water reactor having an elongated hollow metallic tubular cladding for containing nuclear fuel, the tubular cladding having an inner tubular layer of a zirconium alloy with alloying components of molybdenum and 3 to 6 weight percent bismuth, the balance zirconium.

Abstract: Insuring a constant supply of radioisotopes is of great importance to medicine and industry. This invention addresses this problem, and helps to solve it by introducing a new apparatus for transmutation of isotopes which enables swift and flexible production on demand.

Abstract: A process for generating an inerting gas for rendering an atmosphere inert, such as within a containment shell of a nuclear power plant. Inert gas is kept in liquid or solid phase in a first reservoir. A sufficient amount of heat to vaporize the liquefied or solidified inert gas is made available in a heat transfer medium in a second reservoir. When inerting gas is needed, the heat transfer medium and the liquefied or solidified inert gas are brought into thermal contact with one another. An apparatus for generating the inerting gas is provided as well. The process and the apparatus are particularly suitable for generating a large amount of inerting gas, as a result of which it can be ensured that the containment shell of a nuclear power plant is rendered inert within a short time.

Abstract: A nuclear power plant has a cooling system that operates under a variety of temperature and pressure conditions. A storage container is provided to allow expansion of fluid within the cooling system, and access is gained to the interior chamber of the container via a rupture disc. When pressure above a design threshold is exceeded, the rupture disc ruptures allowing fluid to fill the chamber. When desired, a valve may be opened to allow fluid to exit the chamber and travel to a desired location.

Abstract: The control rod (4) carrying absorbing elements (5) contains an operating rod (37) forced upwards by washers (38) and projecting by a push button end (52). When it is decided to uncouple the absorbing elements, the control rod (4) is raised, so that the teeth (62) of ratchets (56) opened out beforehand weigh on the push button (52), lower the operating rod (37) and enable coupling balls (33) to enter a groove (35) on the bottom of the rod, which detaches the pommel (18) carrying the absorbing elements (5). Application to pressurized water nuclear reactors.

Abstract: The spacer comprises a plurality of strips interleaved with one another to form an eggcrate-type pattern defining essentially rectilinear cells for each fuel rod. Each strip includes a central body portion with cantilevered loop spring-like projections extending to opposite sides, with spring contact portions projecting inwardly. Stops are provided along each of the central body regions of the strips intermediate the loop springs that project to the opposite side of the strip. Adjoining walls have loop spring portions for biasing the rod into engagement with opposing stops whereby each fuel rod is supported at six contact points, i.e., four spring contact points and two hard stop contacts opposite the paired spring contacts.

Abstract: A condensation vessel for the measurement of steam pressure includes a steam zone, a steam line which opens in the steam zone at an entrance, a condensate zone which is directly adjacent the steam zone and geodetically below the entrance, and a discharge device which is connected to the steam zone and which serves for a discharge of steam and noncondensable gases from the condensation vessel. A method for operating the condensation vessel includes condensing steam which contains an increased fraction of a noncondensable gas, in particular radiolysis gas, out of the steam zone. The gas is led out of the condensation vessel in dissolved form through the discharge device, with the result that the risk of faulty measurement is largely ruled out, since virtually no gas is dissolved in the condensate within the condensate zone. The condensation vessel can be installed in a simple way, even in the course of retrofitting, for measuring the filling level of a reactor pressure vessel.

Abstract: An apparatus for testing a nuclear fuel assembly for leaks by sweeping a fluid along the fuel assembly while the fuel assembly is disposed in a pool. The apparatus includes a bridge overlying the pool and a mast assembly depending from the bridge. The mast assembly includes an outer, stationary mast and an inner, movable mast adapted to hold the fuel assembly and to position the fuel assembly in the interior channel between the upper and lower ends. The apparatus includes an injection assembly including an injection conduit, a nozzle and a clamp system for securing the nozzle to the outer mast. The apparatus also includes a suction conduit having an inlet disposed in fluid communication with the interior channel for collecting the fluid after the fluid sweeps the fuel assembly.

Abstract: An eddy-current probe (10) is moved in the axial direction of the clad of the rod (1), a first position of the probe (10) is determined in the axial direction, for which a signal from the probe is representative of the presence of the internal surface of the bottom end plug of the rod (1) and at least one second position for which the signal from the probe is representative of the presence of the end part of the spring of the fuel rod (1) or of the internal surface of the top end plug of the fuel rod (1). The total length and/or the length of the fissile stack are calculated from the first position and from the second position of the probe (10). The measurements may be performed inside the spent fuel storage pond of a reactor.

Abstract: A joint for interfacing a steel head closure and a steel-lined prestressed concrete reactor vessel (PCRV). The steel head closure is bolted to a thick steel annular plate and a thermal barrier is arranged in a volume bounded by the head ring, the liner and the concrete of the PCRV wall. The thermal barrier is made of zirconia sand or other material having a low thermal conductivity, a high bulk modulus equal to that of concrete, and a low shear modulus. Differential thermal expansion of the vessel head closure and PCRV is accommodated by a flexible connection of the PCRV liner to the inner periphery of the head ring. In the alternative, the steel head closure is interfaced to the top of the PCRV via a sliding joint or a thermal stress relief ring. In accordance with a further alternative, thermal stresses in the steel vessel head closure are mitigated by reducing the temperature of the head closure by installing thermal insulation on all internal surfaces thereof.

Abstract: The method comprises providing an annular cavity in an internal part of a tapped bore of the guide cone, screwing the tapped bore of the guide cone onto the threaded end of the thermal sleeve and expanding at least part of the end of the thermal sleeve radially into the cavity of the guide cone from inside the thermal sleeve and the guide cone.

Abstract: A fly catcher apparatus has a cylindrical body with a single fly inlet port on its wall, near the bottom thereof. A central tube holds a wick of cloth, sponge or similar liquid-permeable material. Midway up the tube are a series of regularly spaced cloth or sponge-like fly-contacting (and other insect-contacting) members, preferably colored and shaped like leaves. These are attached in fluid communication with the wick and exit out the side of the tube into the interior cavity of the body. At the top of the tube is a cup for holding odoriferous bait, in the form of decaying meat, fish or the like. One or more aroma ports allow the smell of the bait to exit out the removable cap of the cup. Additional perforations for releasing the aroma of bait decay are located on the side wall of the bait cup. The top of the wick forms one or more bait-moistening members which exit out the top or side of the tube into the cup. Moisture carried up the wick keeps the bait moist.

Abstract: A shielded rack loader makes use of a loading rack movable between a shielding structure and a storage tube. A shield plug seals the storage tube. A hoist moves the shield plug and the loading rack. A shield plug cart and a material transfer cart mate with receiving flanges of the rack loader and permit temporary storage and movement of the shield plug and of canisters of transuranic material.

Abstract: A latch pin assembly is configured to enable selective engagement with at least one of the fuel assembly channel and the coolant rod such that the fuel assembly channel and the coolant rod can be selectively utilized to support the fuel assembly load, thereby eliminating the need for fuel tie rods. The latch pin assembly includes a latch pin selectively engageable with the fuel assembly channel and the coolant rod, and an anchoring assembly cooperating with the latch pin, wherein the anchoring assembly anchors the latch pin in a selected position such that the latch pin engages at least one of the fuel assembly channel and the coolant rod. The latch pin may be alternatively engageable with the fuel assembly channel and the coolant rod or simultaneously engageable with the fuel assembly channel and the coolant rod.

Abstract: In a method of construction of a reinforced concrete diaphragm floor of a nuclear reactor reinforced concrete containment vessel, a bottom surface of the diaphragm floor is provided in the form of an iron plate. The iron plate, an iron bar beam portion for supporting the load provided by concrete during a concrete pouring time, and a reinforcing bar member to be buried in the concrete of the diaphragm floor are assembled outside of a building in which the nuclear reactor is to be embodied. The above members are carried using lifting machinery and are set in a permanent receiving member which is provided on both a main body of the nuclear reactor pressure vessel and a steel member serving as a concrete mold frame of an outer wall of the nuclear reactor reinforced concrete vessel. A concrete pouring is carried out in stages so as to form successive layers of concrete during plural pouring times.

Abstract: Prioritization logic determines the final command applied to a process control component from a plurality of commands generated by diverse independent control subsystems, each utilizing different hardware and software to implement a common algorithm to preclude common mode failures. In one embodiment, priority is given to commands generated by one control subsystem, such as a safety grade subsystem, over commands provided by a second, non-safety grade control subsystem. In another embodiment, equal priority is given to commands from two control subsystems. In this case, ambiguous commands from either or both subsystems are ignored, but conflicting commands produce a final command which provides a safe state.