US3697756A

US3697756A - Device for inserting tagged sand into ocean floor

Info

Publication number: US3697756A
Application number: US160390A
Authority: US
Inventors: Elick H Acree; Hugh R Brashear Jr; Forrest N Case
Original assignee: US Atomic Energy Commission (AEC)
Current assignee: US Atomic Energy Commission (AEC)
Priority date: 1971-07-07
Filing date: 1971-07-07
Publication date: 1972-10-10
Anticipated expiration: 1989-10-10

Abstract

A device is provided for introducing an identifiable radioisotope tag into the ocean bottom in such a manner that a radiation material balance can be observed as the sand transport process occurs. The device comprises a cylinder having a motoroperated stirrer for admixing sand and a quantity of isotope tagged sand, the cylinder being mounted on a sled in such a manner that it can be depressed vertically by means of a hydraulic ram into the ocean bottom.

Description

United States Patent Acree et a].

[451 Oct. 10, 1972 DEVICE FOR INSERTING TAGGED SAND INTO OCEAN FLOOR Inventors: Elick H. Acree, Lenoir City; Hugh R. Brashear, Jr., Concord; Forrest N. Case, Oak Ridge, all of Tenn.

The United States of America as represented by the United States Atomic Energy Commission Filed: July 7, 1971 Appl. No.: 160,390

Assignee:

US. Cl. ..250/l06 T, 250/83.6 s

1m. Cl. ..G21h 5/02 Field of Search ..250/83.6 S, 106 T V: 24 v D01! BATTERY}:

[56] References Cited UNITED STATES PATENTS 3,524,062 8/1970 Rocoplan et al...250/83.6 S X 3,532,881 10/1970 Dewan ..250/83.6 S X Primary Examiner-Archie R. Borchelt AtI0meyRoland A. Anderson [57] ABSTRACT A device is provided for introducing an identifiable radioisotope tag into the ocean bottom in such a manner that a radiation material balance can be observed as the sand transport process occurs. The device comprises a cylinder having a motor-operated stirrer for admixing sand and a quantity of isotope tagged sand, the cylinder being mounted on a sled in such a manner that it can be depressed vertically by means of a hydraulic ram into .the ocean bottom.

4 Claims, 1 Drawing Figure PATENTEDum 10 m2, 3 3

24V DC BATIERY Elick H.Acree Hugh R. Brashear, Jr. BY Forrest N. Case ATTORNEY.

INVENTORS.

BACKGROUND OF THE INVENTION This invention was made in the course of, or under, a contract with the United States Atomic Energy Commission.

It is desirable to determine the natural movement of sand along coastal areas. One method of accomplishing this involves tagging sand and utilizing equipment to follow its movements until definite patterns in the sands transport emerge. Such information is important in beach restoration and protection programs. Additionally, such data are needed for the engineering evaluation of marine structure and for basic sand movement studies.

Investigations of sands transport prior to the present invention have revealed that sand taken from one environment and placed in another behaved differently. For this reason, sand indigenous to the area of movement under study must be tagged to provide for any meaningful results. Previous methods of tagging sand involved applying resinous or siliceous materials containing fluorescent dyes. These coatings, however, altered the natural hydraulic properties of sand. In later methods, batches of sand were irradiated in nuclear reactors to make the impurities in sand radioactive. This method was severely limited by the quantity and type of impurities present in the sand.

In the past, it has not been possible to obtain quantitative data concerning the volume of sand or sediment transported by the action of waves and currents acting on the ocean bottom and beaches due to the inability to introduce an identifiable tag into the ocean bottom in such a manner that a material balance could be observed during the course of the transport process. The present invention was conceived to overcome the above problems in a manner to be described hereinbelow.

SUMMARY OF THE INVENTION lt is an object of this invention to practice a method for injecting a tagged core into a volume of ocean bottom which can be monitored in a manner to obtain quantitative data of sand transport.

It is another object of this invention to provide a tagging and dispersing device which will ultimately mix in situ a known quantity of radionuclide in a welldefined volume of ocean bottom thereby enabling accurate measurements to be made of later movements of said bottom.

The above objects have been accomplished in the present invention by providing a thin-walled cylinder, open at one end, which is mounted on a sled in such a manner that the cylinder can be depressed vertically by means of hydraulic rams into the ocean bottom. A motor-operated stirrer comprising a drive motor attached to the top of the cylinder with a shaft extending through the center of the cylinder from the top to bottom facilitates entry of the cylinder into the ocean bottom. Propellers on the shaft provide stirring action. As the propellers are rotated, sand and water are mixed forming a slurry within the cylinder as it is depressed, the cylinder wall serving to isolate the slurry from the outside sand.

Tanks of compressed gas, mounted on the sled, serve to activate the hydraulic rams. The stirrer is electrically operated by means of a battery mounted on the sled. When the cylinder has been depressed to the desired depth, and while the stirrer is in operation, a cap is hydraulically removed from a small chamber containing sand or sediment tagged with an appropriate radionuclide. The chamber is then automatically emp-. tied into the sand and water slurry within the cylinder where it is uniformly distributed. The stirrer is then stopped and the cylinder withdrawn by reversing the force on the hydraulic rams, leaving a well-defined plug containing tagged sand or sediment dispersed throughout the mass. Transfer of the tag from the plug into the environment by the natural forces that cause transport of the ocean bottom may be monitored by detectors placed over the core and by appropriate survey instruments near the core.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE in the drawing is a side view of the device of this invention for inserting tagged sand into a plug of the ocean bottom.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the single FIGURE in the drawing, a side view of the device for inserting tagged sand into the ocean floor is illustrated. A pair of spaced-apart, elongated, tubular, hollow members 1 with upturned opened ends are provided, only one of these members being shown in the drawing since only one can be seen in the side view of the device. The members 1 are parallel to each other and there are suitable brackets, not shown, in the space between the members 1 and affixed thereto for supporting a pair of compressed air tanks 8, only one being shown in the drawing, for supporting a battery 6, and for supporting a thin-walled cylinder 2 and other components associated therewith. The cylinder 2 is opened at its bottom end adjacent to the ocean bottom and is closed at its top end by a suitable plate which supports a motor 3. The motor 3 is connected by a flexible lead 7 to the 24 volt D.C. battery 6. The motor 3 is coupled to a drive shaft 4 which extends nearly to the bottom of the center of the cylinder 2 and a stirrer propeller 5 is affixed to the bottom of the shaft 4, as shown.

Each of the tanks 8 of compressed air is supported by brackets 10 which are affixed to the brackets, not shown, between the hollow members 1. The tank 8, shown in the drawing, is connected to a hydraulic ram member 14, while the other tank 8, not shown, is connected to a similar hydraulic ram member 14' in the same manner. A bracket 12 is affixed to the upper portion of cylinder 2 and to a plunger member 13 associated with the ram member 14. Another bracket member 12' is also affixed to the upper portion of cylinder 2 and to a plunger member 13' associated with the ram member 14'. It should be noted that, in practice, the

members

12, 13, 14 and 12, 13', 14' are rotated from their positions shown in the drawing, being in the position shown only for the sake of clarity. The

ram members

14, 14 are mounted on the support brackets between members 1.

' fixed to the underside of the cover plate member of the cylinder 2. The chamber 9 contains sand or sediment tagged with an appropriate radionuclide. A plunger member 16 is utilized to cover the lower open end of the chamber 9 and is adapted to be hydraulically moved to permit the tagged material in this chamber to be emptied into the cylinder 2 at an appropriate time in the operation of the device to be described below. It should be understood that more than one chamber. 9 may be provided if such is desired or required.

The hollow members 1 with the supporting brackets affixed thereto may be referred to as a sled. The cylinder 2 is mounted on the sled in such a manner that it can be depressed vertically by means of the

hydraulic rams

14, 14 into the ocean bottom. The cylinder 2 is about 12 inches in diameter and 3 feet long. The motor-operated stirrer facilitates entry of the cylinder 2 into the ocean bottom. As the stirrer propellers 5 are rotated, sand and water are mixed forming a slurry within the cylinder as it is depressed, the cylinder wall serving to isolate the slurry from the outside sand. The tanks 8 of compressed air serve to activate the hydrau lic rams 14, 14'. The stirrer motor 3 is electrically operated bymeans of the battery 6 and the motor effects the rotation of the stirrer propeller blades 5.

When the cylinder 2 has been depressed to the desired depth (about l2'inches) and while the stirrer is in operation, the plunger 16 is hydraulically moved by means, not shown, such that the chamber 9 containing the tagged sand is then automatically emptied into the sand and water slurry within the cylinder 2 where it is uniformly distributed. The stirrer is then stopped and the cylinder 2 withdrawn by reversing the force on the hydraulic rams l4, 14', leaving a well-defined plug 15 containing tagged sand or sediment dispersed throughout the mass. It should be understood that the operation of the motor 3, the control of the

hydraulic rams

14, 14' and the control of the position of the tagged sand release device 16 may be effected from an ocean surface ship by conventional control links to these devices, or alternatively these devices may be controlled by a skin diver at the position of the sled assembly on the ocean bottom. Transfer of the tagged material from the plug 15 into the environment by the natural forces that cause transport may be monitored by detectors placed over the core and by appropriate survey instruments near the core.

The tagged sand in the chamber 9 may be tagged using isotopes such as xenon-133, gold-198, gold-199 or cesium l 37, for example.

There arethree components of sediment transport that must be measured in order to obtain data that describes the transport mechanism: 1) direction, (2)

rate of movement, and (3) the depth of movement. Direction of movement can be obtained by injecting a quantity of isotope tagged sand and allowing the sand to disperse. Subsequent surveys of the area to obtain radiation distribution provide position data. The radiation counts can then be plotted anda map constructed to show the direction of transport.

Rate and depth of movement are more difficult to determine but are measurable. If a known quantity of tugged sand is mixed with a known volume or plug of sand in the ocean floor, as transport occurs, the quantity of radioactive material transported through a known distance from the injection point can be measured. The

V volume of sand in unit injection volume R curies per unit injection volume T= elapsed time from injection X, distance from injection point R, curies of material at distance X,.

If the plug containing the tagged sand is monitored continuously, the depth of movement can be determined.

Field experiments have been conducted with the above-described plug injection device using gold 198/ 199 tagged into sand indigenous to the test areas as the tracing material. In all of the field tests, stationary detectors placed over the core injections showed a decrease in activity as a function of time.

Using the above-described method and equipment, it is possible to determine the direction of sediment transport and the average speed of sand movement under the same environmental conditions as the conditions at the time of the survey. This makes it possible to determine varying rates of transport both in a single zone and between different zones. Using knowledge thus obtained, it should be possible to reduce the cost of dredging harbors and building underwater structures. Additionally such information should assist helping to solve the river silting problem.

This invention has been described by way of illustration rather than limitation and it should be apparent that it is equally applicable in fields other than those described.

What is claimed is:,

1. A device for injecting and dispersing a known quantity of radioactive material in a well-defined plug volume of ocean bottom, comprising a sled assembly, a cylinder mounted in a vertical position on said sled assembly, said cylinder providedwith an open end adjacent to said ocean bottom and provided with a top cover plate, a pair of hydraulic ram assemblies mounted to sled assembly and to the upper portion of said cylinder on opposite sides thereof, a pair of compressed air tanks mounted on said sled assembly, means for connecting respective ones of said air tanks to respective ones of said ram assemblies for selectively efi'ecting vertical depression of said cylinder into said ocean bottom to a desired depth to define said plug volume within said cylinder and effecting subsequent withdrawal of said cylinder from said ocean bottom, an electric motor mounted on the top of said cylinder top cover plate, said motor provided with a drive shaft extending through said cylinder cover plate and down through the center of said cylinder to near the bottom thereof, a stirrer propeller mounted on the lower end of said drive shaft, a DC. battery mounted on said sled assembly, a flexible lead wire connected between said battery and said motor for supplying operating power to said motor and thus effecting rotation of said stirrer propeller during said depression of said cylinder into i said ocean bottom and while said cylinder remains at said depressed depth, and at least one small chamber mounted on the underside of said cylinder top cover plate, said chamber containing said radioactive material and provided with a movable plunger for opening said chamber and emptying the contents thereof into said cylinder when said cylinder is fully depressed to said depth into said ocean bottom, said rotating stirrer propeller effecting uniform distribution of said released radioactive material throughout said plug volume in said ocean bottom with said depressed cylinder, whereby after said cylinder is withdrawn from said ocean bottom, the subsequent transport of said radioactive tagged plug volume into its environment by natural forces acting on said ocean bottom may be monitored.

2. The device set forth in claim 1, wherein said sled assembly comprises a pair of elongated, tubular, hollow members provided with upturned opened ends, said hollow members being spaced apartin parallel relation each to the other, and support brackets in the space between said hollow members and affixed thereto, said support brackets supporting said battery, said air tanks and said hydraulic ram assemblies.

3. The device as set forth in claim 1, wherein said cylinder is 12 inches in diameter and said desired depressed depth of said cylinder is 12 inches.

4. The device set forth in claim 1, wherein said radioactive material was tagged utilizing an is isotope selected from the group consisting essentially of xenon- 133, gold 198/199, and cesium-137.

Claims

1. A device for injecting and dispersing a known quantity of radioactive material in a well-defined plug volume of ocean bottom, comprising a sled assembly, a cylinder mounted in a vertical position on said sled assembly, said cylinder provided with an open end adjacent to said ocean bottom and provided with a top cover plate, a pair of hydraulic ram assemblies mounted to sled assembly and to the upper portion of said cylinder on opposite sides thereof, a pair of compressed air tanks mounted on said sled assembly, means for connecting respective ones of said air tanks to respective ones of said ram assemblies for selectively effecting vertical depression of said cylinder into said ocean bottom to a desired depth to define said plug volume within said cylinder and effecting subsequent withdrawal of said cylinder from said ocean bottom, an electric motor mounted on the top of said cylinder top cover plate, said motor provided with a drive shaft extending through said cylinder cover plate and down through the center of said cylinder to near the bottom thereof, a stirrer propeller mounted on the lower end of said drive shaft, a D.C. battery mounted on said sled assembly, a flexible lead wire connected between said battery and said motor for supplying operating power to said motor and thus effecting rotation of said stirrer propeller during said depression of said cylinder into said ocean bottom and while said cylinder remains at said depressed depth, and at least one small chamber mounted on the underside of said cylinder top cover plate, said chamber containing said radioactive material and provided with a movable plunger for opening said chamber and emptying the contents thereof into said cylinder when said cylinder is fully depressed to said depth into said ocean bottom, said rotating stirrer propeller effecting uniform distribution of said released radioactive material throughout said plug volume in said ocean bottom with said depressed cylinder, whereby after said cylinder is withdrawn from said ocean bottom, the subsequent transport of said radioactive tagged plug volume into its environment by natural forces acting on said ocean bottom may be monitored.

2. The device set forth in claim 1, wherein said sled assembly comprises a pair of elongated, tubular, hollow members provided with upturned opened ends, said hollow members being spaced apart in parallel relation each to the other, and support brackets in the space between said hollow members and affixed thereto, said support brackets supporting said battery, said air tanks and said hydraulic ram assemblies.

4. The device set forth in claim 1, wherein said radioactive material was tagged utilizing an is isotope selected from the group consisting essentially of xenon-133, gold 198/199, and cesium-137.