Abstract: A safety shroud of a nuclear reactor coolant pump. Capscrew heads, if broken, are prevented from separating from a nuclear reactor coolant pump having a drive shaft, an impeller secured to the drive shaft, a suction deflector secured to the impeller, and capscrews with outer heads securing the impeller and suction deflector to the drive shaft, by securing a safety shroud over the capscrew heads. The safety shroud may be secured by welding the safety shroud to the impeller or suction deflector, or by bolting the safety shroud to the distal end of the drive shaft.

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 and seal welded to the shield structure. Inner and outer support rings attached to the annular plate are supported by the existing beams in the annular cavity. A U-shaped flexible annular expansion ring positioned between the annular plate and reactor vessel flange has its inner diameter seal welded to the reactor vessel flange and its outer diameter seal welded to the annular plate. Ports in the annular plate provide access to nuclear instruments below the annular plate. A cover plate is removably attachable to each port to seal the ports. A closable drain is provided in the annular expansion ring. This provides a permanent seal plate that allows flooding of the cavity for refueling with it being necessary to remove only the cover plates for normal reactor operations.

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: 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: The spacer pin of this invention is preferably threadably secured to a thermal shield normally found within reactor vessels. It comprises a main body having a cavity therein which houses a locking assembly that alternately engages or disengages the threads of the thermal shield as desired. Ideally, as bolt means are is rotated within the main body, locking keys are either moved into engagement with the threads of the thermal shield or the locking keys are removed from such engagement with the thermal shield. In this fashion, the spacer pin may be locked onto or unlocked from the thermal shield as desired. A locking cap prevents the bolt means from coming unthreaded during use and also insures that the spacer pin remains secured to the thermal shield.

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 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 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 method and apparatus for replacing a nozzle or heater sleeve in a nuclear reactor coolant system pressurizer. The tubular main body portion of the replacement nozzle is threadably received in the nozzle bore after the original heater and damaged heater sleeve have been removed and the nozzle bore partially tapped to provide a threaded area therein. The first or upper end of the main body portion is positioned substantially flush with the interior of the pressurizer. A seal weld is provided between the upper end of the main body portion and the interior of the pressurizer. A flange that extends radially from and adjacent the second or lower end of the main body portion bears against the exterior of the pressurizer when the main body portion is in its installed position inside the heater sleeve bore.

Abstract: In order to supply emergency coolant directly to the core inlet of a nuclear reactor, a separate and distinct channel is located within the reactor vessel. This channel flows downward along the perimeter of the core barrel and discharges its emergency coolant directly to the core inlet. Separate nozzles couple this channel to the supply of emergency coolant.

Abstract: A thimble tube for use in a guide the in a nuclear reactor. The thimble tube is an elongated hollow tube having one end closed. The portion of the tube that extends into the reactor is formed from a plurality of sections attached to each other to form the tube in an alternating fashion along the width and length of the tube. The sections are formed from materials having different coefficients of thermal expansion. This causes the thimble tube to warp into supporting contact with the interior of the guide tube at normal reactor operating temperature.

Abstract: A replacement heater sleeve for a nuclear reactor coolant system pressurizer and method for replacing a damaged original heater nozzle. The original heater and heater nozzle are removed from the pressurizer and the original bore is enlarged. An outer sleeve is installed in the enlarged bore on the same center as the original heater nozzle and is substantially flush with the interior of the pressurizer. The outer sleeve is welded to the pressurizer on its interior and exterior surfaces. An inner sleeve is installed in the inner diameter of the outer sleeve and extends beyond the outer sleeve into the pressurizer. The inner sleeve is welded to the lower end of the outer sleeve and is provided with an inner diameter sized to receive a heater of the same size as that originally installed in the pressurizer. The inner sleeve also maintains the original heater alignment in the pressurizer.

Abstract: A replacement heater sleeve for nuclear reactor coolant system pressurizer and method for replacing a damaged original heater nozzle. The original heater and heater nozzle are removed from the pressurizer and the original bore is enlarged. An outer sleeve is installed in the enlarged bore on the same center as the original heater nozzle and is substantially flush with the interior of the pressurizer. The outer sleeve is welded to the pressurizer on its interior and exterior surfaces. An inner sleeve is installed in the inner diameter of the outer sleeve and extends beyond the outer sleeve into the pressurizer. The inner sleeve is welded to the lower end of the outer sleeve and is provided with an inner diameter sized to receive a heater of the same size as that originally installed in the pressurizer. The inner sleeve also maintains the original heater alignment in the pressurizer.

Abstract: A locking bolt assembly that prevents the release of loose parts in the event of bolt failure. A bolt having a head and threaded main body portion is provided with a central bore through the head and main body portion. The central bore has a necked down area adjacent the end of the main body portion away from the head. A plurality of slots along the end of the main body portion in communication with the central bore form bolt fingers around the necked down area. A plunger slidably received in the central bore places radial pressure at the necked down area to expand the bolt fingers outwardly and lock the bolt in its installed position without changing the preload of the installed bolt. The plunger is retained in its bolt locking position and prevents the release of loose parts in the event of bolt failure.

Abstract: An electronic feeler gauge for measuring the dimension of a gap. A flexible base in the general shape or a shoehorn has a raised shoulder portion of greater thickness substantially along its rear half with a forwardly extending tab that acts as a stop. A strain gauge mounted substantially in line with the tab at the lower portion of the concave curve of the flexible base only measures strain across the width thereof. Electrical signals from the strain gauge are conducted to a strain meter by electrical wires for analyzing the signals and converting them to readings indicating the size of the gap into which the flexible base in inserted.

Abstract: A flexureless insert guide assembly. An annular shaped body inserted through the hole in a guide structure card has spring loaded arms pivotally mounted in the body which snap outward to retain the assembly in place. The assembly has an exterior groove adapted to receive removal tooling which causes retraction of the arms for removal of the assembly.