Buoyancy elevator for moving a load in an industrial facility such as a nuclear power plant

A cask handling system for transporting a nuclear fuel shipping cask between upper and lower elevations in a nuclear facility comprising a vertical shaft for containing liquid therein extending between the upper and lower elevations, the cask being submerged in the liquid when at the lower elevation, the extent of the shaft between said elevations having a substantially constant horizontal cross-section, a submersible buoy disposed in the shaft and having an upwardly facing surface for supporting the cask and transporting the cask between said elevations in said shaft;

• buoyancy control means for controlling the buoyancy of said buoy to cause said buoy to ascend and descend in said shaft comprising a chamber formed in said buoy and communicating with the liquid in said shaft;
• and, gas control means for supplying gas under pressure to said chamber for expelling liquid therefrom whereby the buoyant forces acting on said buoy are increased and for venting said gas from said chamber for causing liquid to enter said chamber whereby the buoyant forces acting on said buoy are reduced, said gas control means comprising upper elevation sensor means for sensing the upward buoyant force acting on said buoy at said upper elevation when said buoy is in a condition of positive buoyancy, and an indicator connected to said upper elevation sensor means for indicating when the gas vented from said chamber places said buoy in a condition of negative buoyancy, said buoy having a horizontal cross-section closely fitted to the horizontal cross-section of the shaft with a narrow clearance between the side of the buoy and the side of the shaft, the narrow clearance enabling liquid therein and the movement of liquid therein to impede movement of said buoy within said shaft.

A cask handling system for transporting a nuclear fuel shipping cask between upper and lower elevations in a nuclear facility comprising a vertical shaft for containing liquid therein extending between the upper and lower elevations, the cask being submerged in the liquid when at the lower elevation, the extent of the shaft between said elevations having a substantially constant horizontal cross-section, a submersible buoy disposed in the shaft and having an upwardly facing surface for supporting the cask and transporting the cask between said elevations in said shaft, said buoy having an elongated cavity extending vertically from adjacent the top portion to adjacent the bottom portion of the buoy, the length of the cavity substantially corresponding to the vertical length of the cask, the upper portion of the cavity being open for receiving the cask within the cavity, the bottom portion of the cavity being adopted to support the bottom portion of the cask;

• removable sealing means for sealing said cavity when the cask is in place in said buoy to prevent penetration of the liquid of said shaft into said cavity during the travel of said buoy between said elevations;
• buoyancy control means for controlling the buoyancy of said buoy to cause said buoy to ascend and descend in said shaft, said buoy having a horizontal cross-section closely fitted to the horizontal cross-section of the shaft with a narrow clearance between the side of the buoy and the side of the shaft, the narrow clearance enabling liquid therein and the movement of liquid therein to impede movement of said buoy within said shaft.

A cask handling system for transporting a nuclear fuel shipping cask between upper and lower elevations in a nuclear facility comprising a vertical shaft for containing liquid therein extending between the upper and lower elevations, the cask being submerged in the liquid when at the lower elevation, the extent of the shaft between said elevations having a substantially constant horizontal cross-section, a submersible buoy disposed in the shaft and having an upwardly facing surface for supporting the cask and transporting the cask between said elevations in said shaft;

• buoyancy control means for controlling the buoyancy of said buoy to cause said buoy to ascend and descend in said shaft comprising a chamber formed in said buoy and communicating with the liquid in said shaft;
• and, gas control means for supplying gas under pressure to said chamber for expelling liquid therefrom whereby the buoyant forces acting on said buoy are increased and for venting said gas from said chamber for causing liquid to enter said chamber whereby the buoyant forces acting on said buoy are reduced, said gas control means comprising lower elevation sensor means for sensing the downward load of said buoy at said lower elevation when said buoy is in a condition of negative buoyancy, and an indicator connected to said lower elevation sensor means for indicating when the gas under pressure supplied to said chamber from said pressure supply means places said buoy in a condition of positive buoyancy, said buoy having a horizontal cross-section closely fitted to the horizontal cross-section of the shaft with a narrow clearance between the side of the buoy and the side of the shaft, the narrow clearance enabling liquid therein and the movement of liquid therein to impede movement of said buoy within said shaft.

A cask handling system for transporting a nuclear fuel shipping cask between upper and lower elevations in a nuclear facility comprising a vertical shaft for containing liquid therein extending between the upper and lower elevations, the cask being submerged in the liquid when at the lower elevation, the extent of the shaft between said elevations having a substantially constant horizontal cross-section, a submersible buoy disposed in the shaft and having an upwardly facing surface for supporting the cask and transporting the cask between said elevations in said shaft;

• buoyancy control means for controlling the buoyancy of said buoy to cause said buoy to ascend and descend in said shaft, said buoy having a horizontal cross-section closely fitted to the horizontal cross-section of the shaft with a narrow clearance between the side of the buoy and the side of the shaft, the narrow clearance enabling liquid therein and the movement of liquid therein to impede movement of said buoy within said shaft, said cask handling system further comprising dash-pot means disposed at the lower elevation of said shaft for co-acting with said buoy to decelerate the same as said buoy reaches said lower elevation, said dash-pot means comprising an annular cavity formed in the base of said buoy, said cavity being of a U-shape when viewed from a vertical cross-section of it and, an annular structure protruding from the base of said shaft and dimensioned so as to fill said cavity as said buoy reaches said lower elevation whereby the liquid in said cavity is forced therefrom thereby decelerating said buoy as the same reaches said lower elevation.

A method for lowering and raising a cask for transporting nuclear fuel elements between upper and lower elevations in a nuclear facility by means of a buoy which is supported by buoyancy in a shaft containing liquid, the buoy, having a hollow interior portion adapted to serve as a buoyancy chamber the method comprising the step of:

• a. establishing a magnitude of positive buoyancy for the buoy substantially corresponding to the weight of the cask which is to be transported;
• b. placing the cask upon the buoy when the buoy is adjacent the upper elevation with the positive buoyancy of the buoy maintaining it substantially stationary;
• c. reducing the magnitude of positive buoyancy to cause the buoy with the cask to descend with respect to the shaft from the upper elevation;
• d. restricting the clearance between the buoy and the shaft in which the buoy is supported by buoyancy to an extent that the movement of liquid with respect to the exterior of the buoy and through the clearance between the buoy and the shaft provides forces in a direction opposite to the travel of the buoy during ascent and descent within the shaft, whereby the restraining forces oppose the onset of excessive rates of travel of the buoy;
• e. terminating the descent of the buoy at the lower elevation to enable fuel elements to be moved with respect to the cask including providing an open chamber adjacent the bottom portion of the shaft with the opening of the chamber facing the bottom portion of the buoy and adapted to receive the bottom portion of the buoy within the opening and advancing the bottom portion of the buoy into the opening of the chamber during the final portion of the descent of the buoy within the shaft, the advancing of the bottom portion of the buoy into the opening of the chamber evacuating liquid from the chamber and producing forces in opposition to the descent of the buoy, whereby the buoy is decelerated during the final portion of the descent in the shaft;
• and
• f. re-establishing a magnitude of positive buoyancy to cause the buoy with the cask to ascend with respect to the shaft to the upper elevation.

A system for lowering and raising a massive load between upper and lower elevations in a facility comprising shaft means for containing liquid therein extending between said elevations;

• a submersible buoy disposed in the shaft having an upwardly facing surface for accommodating the load thereon and for transporting the same between said elevations in said shaft;
• the load being submerged beneath the liquid at the lower elevation;
• the shaft means being tubular in form and having a predetermined transverse cross-section and wherein the buoy extends along a portion of the length of the shaft means and has a transverse cross-section substantially corresponding to that of the shaft means with a predetermined clearance with respect thereto, movement of the buoy within the shaft means causing a passage of liquid through the predetermined clearance, the passage of liquid from the portion of the shaft means toward which the buoy ascends or descends and through the predetermined clearance between the buoy and the shaft means causing forces which are in a direction opposite to the ascent or descent of the buoy, whereby the buoy is restrained from excessive velocities during ascent or descent;
• and, buoyancy control means for controlling the buoyancy of said buoy to cause the same to ascend and descend in said shaft means including a chamber formed in said buoy and communicating with the liquid in said shaft and, gas control means for supplying gas under pressure to said chamber for expelling liquid therefrom whereby the buoyant forces acting on said buoy are increased and for venting said gas from said chamber for causing liquid to enter said chamber whereby the buoyancy forces acting on said buoy are reduced, said gas control means comprising upper elevation sensor means for sensing the upward buoyant force acting on said buoy at said upper elevation when said buoy is in a condition of positive buoyancy, and an indicator connected to said upper elevation sensor means for indicating when the gas vented from said chamber places said buoy in a condition of negative buoyancy.

A system for lowering and raising a massive load between upper and lower elevations in a facility comprising shaft means for containing liquid therein extending between said elevations;

• a submersible buoy disposed in the shaft having an upwardly facing surface for accommodating the load thereon and for transporting the same between said elevations in said shaft;
• the load being submerged beneath the liquid at the lower elevation;
• the shaft means being tubular in form and having a predetermined transverse cross-section and wherein the buoy extends along a portion of the length of the shaft means and has a transverse cross-section substantially corresponding to that of the shaft means with a predetermined clearance with respect thereto, movement of the buoy within the shaft means causing a passage of liquid through the predetermined clearance, the passage of liquid from the portion of the shaft means toward which the buoy ascends or descends and through the predetermined clearance between the buoy and the shaft means causing forces which are in a direction opposite to the ascent or descent of the buoy, whereby the buoy is restrained from excessive velocities during ascent or descent;
• and, buoyancy control means for controlling the buoyancy of said buoy to cause the same to ascend and descend in said shaft means including a chamber formed in said buoy and communicating with the liquid in said shaft and, gas control means for supplying gas under pressure to said chamber for expelling liquid therefrom whereby the buoyant forces acting on said buoy are increased and for venting said gas from said chamber for causing liquid to enter said chamber whereby the buoyancy forces acting on said buoy are reduced, said gas control means comprising lower elevation sensor means for sensing the downward load of said buoy at said lower elevation when said buoy is in a condition of negative buoyancy, and an indicator connected to said lower elevation sensor means for indicating when the gas under pressure supplied to said chamber from said pressure supply means places said buoy in a condition of positive buoyancy.

A system for lowering and raising a massive load between upper and lower elevations in a facility comprising shaft means for containing liquid therein extending between said elevations;

• a submersible buoy disposed in the shaft having an upwardly facing surface for accommodating the load thereon and for transporting the same between said elevations in said shaft;
• the load being submerged beneath the liquid at the lower elevation;
• the shaft means being tubular in form and having a predetermined transverse cross-section and wherein the buoy extends along a portion of the length of the shaft means and has a transverse cross-section substantially corresponding to that of the shaft means with a predetermined clearance with respect thereto, movement of the buoy within the shaft means causing a passage of liquid through the predetermined clearance, the passage of liquid from the portion of the shaft means toward which the buoy ascends or descends and through the predetermined clearance between the buoy and the shaft means causing forces which are in a direction opposite to the ascent or descent of the buoy, whereby the buoy is restrained from excessive velocities during ascent or descent;
• and, buoyancy control means for controlling the buoyancy of said buoy to cause the same to ascend and descend in said shaft means including a chamber formed in said buoy and communicating with the liquid in said shaft and, gas control means for supplying gas under pressure to said chamber for expelling liquid therefrom whereby the buoyant forces acting on said buoy are increased and for venting said gas from said chamber for causing liquid to enter said chamber whereby the buoyancy forces acting on said buoy are reduced, said gas control means including ascent protection means for limiting the amount of gas supplied to said chamber thereby limiting the maximum degree of positive buoyancy of said buoy comprising a tube extending vertically into and communicating with said chamber for taking up the gas supplied to said chamber after an amount of liquid has been expelled whereby the liquid remaining in said chamber limits the maximum degree of positive buoyancy which can occur thereby limiting the rate of ascent of said buoy in said shaft.

A method for lowering and raising a massive load between upper and lower elevations in a facility by means of a submersible buoy which is supported by buoyancy in a shaft containing liquid, the buoy having an upwardly facing surface for accommodating the load therefore and transporting the same between said elevations, a hollow interior portion adapted to serve as a buoyancy chamber, the method comprising the steps of:

• a. establishing a magnitude of positive buoyancy for the buoy substantially corresponding to the weight of the load which is to be transported;
• b. placing the load upon the buoy when the buoy is adjacent the upper elevation with the positive buoyancy of the buoy maintaining it substantially stationary;
• c. reducing the magnitude of positive buoyancy to cause the buoy with the load to descend with respect to the shaft from the upper elevation;
• d. restricting the clearance between the buoy and the shaft in which buoy is supported by buoyancy to an extent that the movement of liquid with respect to the exterior of the buoy and through the clearance between the buoy and the shaft provides forces in a direction opposite to the travel of the buoy during ascent and descent within the shaft, whereby the restraining forces oppose the onset of excessive rates of travel of the buoy,
• e. terminating the descent of the buoy at the lower elevation and providing an open chamber adjacent the bottom portion of the shaft with the opening of the chamber facing the bottom portion of the buoy and adapted to receive the bottom portion of the buoy within the opening and advancing the bottom portion of the buoy into the opening of the chamber during the final portion of the descent of the buoy within the shaft, the advancing of the bottom portion of the buoy into the opening of the chamber evacuating liquid from the chamber and producing forces in opposition to the descent of the buoy, whereby the buoy is decelerated during the final portion of the descent in the shaft;
• and
• f. re-establishing a magnitude of positive buoyancy to cause at least one of the buoy and the buoy with the load to ascend with respect to the shaft to the upper elevation.