Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to explosion proof storage facilities and more particularly to methods for storing and recovering material likely to be exposed to nuclear explosions.
2. Description of the Prior Art
There is currently no recognized method for constructing a facility which can be protected against the effects of a direct hit by a nuclear weapon and later be made available for use at the earth's surface. It is known, however, that the effects of a nuclear weapon attack can be survived if the facility being protected is buried deep enough in the earth. Given a defined nuclear threat, it is possible to go deep enough to survive that threat. The reason no previous system has been successful is that after surviving a nuclear attack, there has been no viable way to get back to the earth's surface.
Therefore, it is the object of the present invention to provide a way to construct accessable storage far enough below the earth's surface to withstand the effects of a direct nuclear attack while allowing rapid return of the storage facility to the earth's surface after the nuclear attack.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross section through a portion of the earth disclosing the practicing of the present invention with the storage facility in its buried position.
FIG. 2 shows the method of access to the storage facility of FIG. 1 under normal maintenance conditions.
FIG. 3 shows the method of access to the storage facility of FIG. 1 following a nuclear attack.
FIG. 4 shows the alternate method of providing the required winding means within the storage container.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the accompanying text and drawings of this specification the present invention is shown being used to store and retrieve an ICBM. While this is the primary motivation leading to the discovery of the present invention, it is to be understood that the technique will work equally well on a smaller scale for the storage and protection of any valuable object. Examples are: papers and works of art or on a larger scale for the protection of groups of individuals by providing life support systems within the sealed container.
Referring first to FIG. 1, the present invention is shown in its static state with the facility in its stored safe position. A shaft 10 is first excavated into the earth 12 through the soil layer 14 and into the rock layer 16 to a depth sufficient to substantially guarantee survival from weapon effects. This distance is generally in excess of five-hundred feet. The diameter of the shaft 10 must be only large enough to allow a storage container 18 to rise in the shaft 10 while allowing for the passage thereby in a downward direction of debris (not shown) sinking in the shaft 10 and negotiating any bends and discontinuities in the shaft 10 following a nuclear attack. A water tank 20 for the storage of fluidizing water 22 is placed at the bottom of shaft 10 and secured in that position. The water tank 20 is provided with inner tanks 24 for the storage of compressed gas 26 communicating with the water tank 20 so that compressed gas 26 can be released into water tank 20 causing fluidizing water 22 to be forced out manifold 28. In alternate embodiments inner tanks 24 could be placed outside water tank 20 and/or contain gas generators or motor operated pumps to effect the discharge of fluidizing water 22 to be forced out manifold 28. Water tank 20 is further connected to surface water supply 30 by umbilical connector 32 controlled by surface support structure 34. The storage container 18 is anchored to the bottom of the shaft 10 by tether 36. Winding means 37 are provided communicating through umbilical connector 32 and tether 36 to surface support structure 34 for letting out or taking in tether 36 so that storage container 18 can rise to or be pulled down from the surface of the earth 12. While winding means 37 is shown in FIGS. 1, 2 and 3 as being attached to the water tank 20, it can equally well be placed in the bottom of the storage container 18 as in FIG. 4. This latter method would be particularly suited to a storage container for safeguarding personnel wherein a handcrank (not shown) could be provided for emergency operation. Shaft 10 is first filled with saturated compacted fine sand 38 prior to initial placement of storage container 18 into shaft 10.
Normal access to the storage container 18 is provided by the method shown in FIG. 2. Fluidizing water 22 is pumped under the control of surface support structure 34 from surface water supply 30 through umbilical connector 32 to water tank 20 and thence out manifold 28. As fluidizing water 22 rises in shaft 10, the sand 38 is fluidized to a "quicksand" condition having a density of approximately 115 lbs/ft.sup.3. The storage container 18 is constructed and filled so as to have a loaded density of 100 lbs/ft.sup.3 or less in order to maintain a positive buoyancy. If winding means 37 is activated to allow the tether 36 to unwind, the storage container 18 will float to the top where the contents can be accessed. Upon reclosing storage container 18, winding means 37 can rewind tether 36 to draw the storage container 18 to the bottom. Upon stopping the flow of fluidizing water 22, sand 38 in shaft 10 will again assume a compacted, non-fluidized state as sand 38 settles and fluidizing water 22 collects at the top of shaft 10. The top portion of shaft 10 is then refilled with sand 38 which will have overflowed during the fluidization process.
In the event of a nuclear attack, surface support structure 34 and surface water supply 30 will, in all probability, be destroyed along with all external power sources, leaving the configuration of FIG. 3. Rock and debris 40 will cover shaft 10. Means responsive to external signals, timed, or responsive to signals from personnel or equipment in storage container 18 will have to be provided as part of winding means 37 to activate the post nuclear recovery of storage container 18. At the appropriate time, compressed gas 26 is released from inner tanks 24 into water tank 20 causing fluidizing water 22 to exit from manifold 28 to fluidize sand 38. Simultaneously, tether 36 is unwound or disconnected as by an explosive squib (not shown) to allow storage container 18 to rise freely to the surface. As sand 38 becomes fluidized, the rock and debris 40 over the top of shaft 10, having a density of 140 to 160 lbs/ft.sup.3, will sink and pass by the rising storage container 18. Upon arriving at the surface, storage container 18 can be opened to recover its contents, or, open automatically to fire its contents as shown in FIG. 3.
The invention described herein has been tested on a subscale laboratory basis and was found to work as anticipated. Quicksand has a fluid density of about 115 lbs/ft.sup.3 and an apparent viscosity which decreases as the rate of water flow is increased. The capsule was found to float nicely upward and pass the rock and rubble which were sinking without any problem .