Abstract: A nuclear propulsion reactor. A reactor vessel is provided with an annular first core and a cylindrical second core that is radially encompassed by the first core. Nuclear fuel elements in the first core provide first stage heating of propellant as they direct the propellant axially through the first core. The second core, which contains fissionable material in a highly refractory form, is in fluid communication with the first core for receiving the heated propellant. Fission reactions in the second core driven by leakage neutrons from the first core provide second stage heating of the propellant as it passes therethrough. The second core directs the coolant to a propellant nozzle for providing propulsive thrust.

Abstract: A method for replacing a nozzle in a pressure vessel. The existing nozzle is cut approximately at the inside surface of the pressure vessel wall. The portion of the existing nozzle that extends beyond the exterior of the pressure vessel wall is removed. A weld pad is deposited on the exterior of the pressure vessel wall around the nozzle bore. The remainder of the existing nozzle is removed. A corrosion resistant thermal spray coating is applied to the nozzle bore. A replacement nozzle is installed in the nozzle bore and seal welded to the weld pad on the exterior of the pressure vessel wall.

Abstract: An upper end fitting for a nuclear fuel assembly. A main body portion that is square in section has a base rigidly attached thereto. A combined pedestal and holddown spring assembly received in the main body portion is formed from leaf springs attached together by a bolt and nut. The leaf springs are bolted together such that the exterior radius or convex surface of the springs face each other. The bolt and nut are sized and shaped to serve as the pedestal for the control assembly of the reactor. A spring retainer movably received in the main body portion retains the springs inside the main body portion. The retainer is also provided with a bore therethrough sized to allow the bolt/pedestal to extend therethrough.

Abstract: A grid key for interior grid cells. A rectangular main body portion is bent near the middle at approximately a 90 degree angle. Two tabs that are flush with the main body portion extend outward in opposite directions from one end and along a portion of the length of the main body portion. The opposing side of the tabs is tapered at a 45 degree angle back toward the main body portion. The main body portion has a thickened section that coincides with the tabs. The thickened section is wedged between the soft stops of an individual interior grid cell to retract the stops and allow loading of a fuel rod.

Abstract: A replacement nozzle and method for replacing a nozzle in a pressure vessel. The original nozzle is removed and a weld preparation is machined into the original weld. The vacated nozzle hole is partially drilled out from the interior of the vessel. A weld land sleeve is received in the drilled out portion of the nozzle hole and a replacement nozzle is received in the weld land sleeve. The sleeve and replacement nozzle are welded in place on the inside of the vessel wall.

Abstract: An inspection device for the upper internals of a nuclear reactor comprising an elongated probe body which is lowered through a central aperture in a support plate that forms part of the upper internals and includes a plurality of vertically extending control rod apertures. Radial channels extend outwardly from the central aperture, each communicating with corresponding control rod apertures. A radially moveable transducer is mounted to the probe body and the latter is rotatable to a position for accessing each channel for radially moving the transducer into the channel. The transducer detects the profile of the channel. An area of particular interest is the area of communication between the channels and the control rod apertures. This area is susceptible to wear due to vibrations of the control rods.

Abstract: A thermionic reactor for providing electrical power and propulsion power. A reactor vessel has a plurality of thermionic heat pipe modules located therein and spaced apart on a hexagonal pitch. Nuclear fuel elements are positioned in the spaces between the thermionic heat pipe modules. Insulating material is provided between the reactor vessel and the array of thermionic heat pipe modules and nuclear fuel elements. Propulsion power is provided by a propellant storage tank and propellant nozzle in fluid communication with opposite ends of the reactor vessel. The thermionic heat pipe modules serve to produce electricity and aid in removal of waste heat.

Abstract: A method for improving the corrosion resistance of a zirconium-based material in an acid environment. A laser beam is scanned across the entire surface of the material to cause surface melting of the material. A rapid self-quenching is provided by the underlying substrate. Homogeneous material formed during solidification of the molten pool improves the corrosion resistance. Alloy enriched diffuse regions, i.e., tin and iron, develop parallel to each other and the periphery of the edge of the melt pool. In this manner, the laser surface melting removes the intermetalics by dissolving the precipitates, thus removing the source of localized corrosion. This greatly reduces the capability of the iron to act anodically to cause the zirconium to ionize, disassociate from the matrix, and migrate into the acid solution.

Abstract: A nuclear reactor vessel cavity seal plate. An annular support plate is positioned over the cavity between the reactor vessel and the shield structure. The inner diameter of the support plate rests freely upon the reactor vessel flange to allow movement of the vessel thereunder during thermal expansion and contraction. A flexible annular seal positioned over the support plate has its inner diameter seal welded to the reactor vessel flange and its outer diameter seal welded to the shield structure. Matching ports in the support plate and seal provide access to nuclear instruments below the support plate. A mounting block around each port accepts a cover plate that seals the port. This provides a permanent seal plate that allows flooding of the cavity for refueling with it only being necessary to remove the cove plates for normal reactor operations.

Abstract: A method and apparatus for replacing an existing fuel guide pin in an upper core plate of a nuclear fuel assembly. The existing guide pin is removed to the level of the bottom of the core plate and inside the bore in the core plate to a point adjacent the pin retaining nut. A longitudinal bore is then created in the remaining portion of the existing fuel guide pin. A replacement fuel guide pin formed from a pin body, collet lock, and bolt is inserted into the bore in the upper core plate and through the bore in the remaining portion of the existing pin. The bolt and collet lock are inserted into bore at opposite ends of the pin body and threaded together. A tapered shoulder at one end of the collet lock passes through the bore created in the existing guide pin and secures the replacement guide pin to the remaining portion of the existing pin.

Abstract: A device for restricting the motion of a thimble tube in a nuclear reactor during normal reactor operating conditions. A cylindrical sleeve open at each end has upper, middle, and lower sections. The upper section has an over-expanded area adjacent the top end to aid in proper positioning in the lower core support plate. The middle section is formed from inner and outer sections attached at their ends and formed from material having different coefficients of thermal expansion. The inner portion of the middle section moves from a first normal relaxed state during cold conditions in the reactor to a second flexed state during hot conditions in the reactor to provide a clamping action on the thimble tube received by the sleeve. A baffle in the lower section reduces coolant flow velocity and pressure through the sleeve.

Abstract: A containment device for contaminated building demolition. A pre-engineered rigid steel frame building is supported on rail trucks movable on railroad tracks. The railroad tracks are positioned on opposite sides and along the length of the contaminated building to be demolished. The rigid steel frame building has one open end and is sized larger than the width and height of the contaminated building. This allows a portion of the contaminated building to be movably enclosed by the pre-engineered building. A flexible liner material inside the pre-engineered building, at the open end attached to the contaminated building, and at the bottom of the pre-engineered building draped to be in contact with the ground seals off the interior of the pre-engineered building to prevent the release of contaminated particles during demolishing operations. A hoist and cable are used to move the pre-engineered building on the railroad tracks.

Abstract: A replacement nozzle and heater sleeve for a nuclear reactor coolant system pressurizer. The heater, damaged heater sleeve exterior of the pressurizer and a portion of the heater sleeve inside the heater sleeve bore are removed. The heater sleeve bore is partially tapped to provide threads at its lower end. A sleeve having a first seal ring positioned at its upper end is threaded into the heater sleeve bore such that the first seal ring presses against the original heater sleeve and provides a seal. A second seal ring on a flange on the sleeve is pressed into sealing engagement with the exterior of the pressurizer.

Abstract: A positioning spine for driving equipment used in inspecting tubing. A helical extension spring has a plurality of wheeled carriers mounted thereon at selected intervals. Wheels mounted on each carrier rotate in planes radial to the spring to allow the positioning spine to travel through tubes having bends in more than one plane. Each carrier is formed from two body sections that are fastened together around the spring.

Abstract: A nuclear fuel rod consolidation structure. A storage canister has a grid structure positioned in its interior. The grid structure is provided with a plurality of hexagonally shaped individual cells in a triangular pitch array. This provides nearly a two to one consolidation ratio. The grid structure provides positive radial support to the fuel rods to maintain the triangular pitch array if the canister is not fully loaded or some of the fuel rods are removed. The positive guidance allows use of the existing rod pulling device for loading fuel rods into the structure.

Abstract: A tool positioning assembly for use inside a steam generator. A loading tool assembly removably attachable to a support base is used to insert the support base into the steam generator through a manway opening. The support base is removably attached to the steam generator at the manway. A retractable foot assembly pivotally attached to the support base stabilizes the support base inside the steam generator. A track assembly, removably attachable to the support base after removal of the loading tool assembly, receives an arm. A driven cogwheel on the waist of the manipulator engages a rack on the track assembly and support base for selectively driving and positioning the arm thereon. A tool coupling mounted on the arm is adapted to receive remotely controlled tools. The four degree-of-freedom movement of the arm provides access to all tubes in the tubesheet and allows mounting of tools outside the steam generator.

Abstract: A pneumatic transport apparatus. A main terminal and a remote terminal each have one end of a carrier tube connected thereto. A sub-carrier is slidably received in each terminal for vertical movement therein. Means are provided at each terminal for locking the sub-carrier in the upper portion of the terminal. A carrier for transporting items between the terminals is received within the sub-carriers and moved between terminals through the carrrier tube. Reversible motors are mounted on a housing at the main terminal that is in communication with the terminal for selectively creating pressure or suction therein to cause the carrier to move from one terminal to the other.

Abstract: A trash receptacle having a main body portion including side walls and an open top and closed bottom, one of the side walls being provided with a recessed area adjacent its bottom. A pedal pivotally mounted on one end at the bottom of the recessed area is retained in a first or normally retracted position adjacent the main body portion by a spring in contact with the pedal. Pressure on the pedal moves it to a second or lowered substantially horizontal position for holding the trash receptacle down by foot pressure while removing a bag liner.

Abstract: A method and apparatus for replacing an existing fuel guide pin in an upper core plate of a nuclear fuel assembly. The existing guide pin is removed to the level of the bottom of the core plate and inside the bore in the core plate to a point adjacent the pin retaining nut. A longitudinal bore is then created in the remaining portion of the existing fuel guide pin. A replacement fuel guide pin formed from a pin body, collet lock, and bolt is inserted into the bore in the upper core plate and through the bore in the remaining portion of the existing pin. The bolt and collet lock are inserted into a bore at opposite ends of the pin body and threaded together. A tapered shoulder at one end of the collet lock passes through the bore created in the existing guide pin and secures the replacement guide pin to the remaining portion of the existing pin.

Abstract: A serpentine tube inspection positioning spine formed from a plurality of identical links. Each link has a convex first end and concave second end spaced along the longitudinal axis of the link whereby adjacent links may be mated together. An axially extending bore in each link receives a continuous cable maintained under tension by a spring attached to one end of the cable. This places pressure on the links that serves to maintain the mated links in a rigid straight configuration while under compressive forces during insertion into a tube to be inspected. The resilience of the spring also allows pivoting of adjacent links for travelling through a bend in the tube.