Note: Descriptions are shown in the official language in which they were submitted.
RADIOACTIVITY SHIELDING
TRANSPORTATION ASSEMBLY AND METHOD
Background of the Invention
This invention relates generally to a protective assem-
bly in which a radioactive substance can be transferred and
a related method of so transferring the substance and more
particularly, but not by way of limitation, to a radio-
activity shielding container and method of using the same in
transferring a radioactive substance directly to a receiver
without substantially disassembling the container.
In the medical industry liquid radioactive tracer sub-
stances are used for various purposes. Such tracers are
often transported in receptacles which are packaged to pro-
vide some degree of radioactivity shielding. In the oil
industry, particulate radioactive tracer substances have
been used in fracturing activities to detect where fractures
have been made. At the present time, liquid radioactive
tracer substances are also being used in the oil industry
for a similar purpose.
Some advantages of using such liquid tracers in the oil
industry are that the tracers can be pumped directly into
the well at high pressures with conventional pumping equip-
ment, the tracers can be accurately volumetrically metered,
and the tracers can be shipped in concentrated forms so that
small shipping packages can be used.
These usages, both in the medical and oil industries,
bring people, equipment and the surrounding environment into
association with, and thus into potential exposure to and
~,-
~ ~'J`~3~j
contamination from, the radioactive substances, which sub-
stances can be very absorbent in liquid form and which sub-
stances can have large radiation exposure levels associated
with small amounts in concentrated form. Furthermore, the
used packaging, which can have a significant residue of the
tracer or otherwise be contaminated, can also provide a
health risk if it is not properly constructed and handled.
In view of these risks of radiation exposure and contamina-
tion, the packaging in which such substances are transported
from their points of being charged with the radioactive sub-
stances to their points of being discharged of the sub-
stances must be carefully manufactured and handled. Depend-
ing upon the nature of the use to which the packaging is to
be put, such packaging may even need to meet governmental
regulations, such as of the type promulgated by the United
States Department oE Transportation.
Two types of packaging, one used in the medical industry
and the other used in the oil industry, are known to me.
One type includes a syringe body which is concentrically
received within a removable cylindrical lead jacket. This
syringe body and jacket are placed in a carrying housing
having a removable cap which is used to close the open end
of the housing once the syringe and jacket assembly are
placed inside the housing.
A shortcoming of this type of packaging is that the
syringe body, which is made of a material that does not pro-
vide any significant radioactivity shielding, can be easily
~ ~V ~ r,;
panying drawings.
Brief Description of the Drawings
FIG. 1 is a sectional elevational view of a first pre-
ferred embodiment of the container of the present inven-
tion.
FIG. 2 is a sectional elevational view of a second pre-
ferred embodiment of the container of the present inven-
tion.
FIG. 3 is an elevational view of part of a mold for con-
structing the embodiment shown in FIG. 2.
FIG. 4 is an end view of the mold shown in FIG. 3.
FIG. 5 is a side elevational view of another portion of
the mold used in association with the portion shown in FIGS.
3 and 4.
FIG. 6 is an end elevational view of the portion of the
mold shown in FIG. 5.
FIG. 7 is a sectional elevational view showing the mold
assembled with a sleeve from which the embodiment shown in
FIG. 2 is manufactured.
FIG. 8A is a sectional elevational view of the assembly
shown in FIG. 2 having an unloaded syringe disposed
therein.
FIG. 8B is the same view as shown in FIG. 8A but with
the syringe filled with radioactive substance.
FIGS. 9(a)-(j) are schematic drawings depicting a pre-
ferred usage of the present invention.
f ~
separated from the protective cylindrical sleeve during use.
Furthermore, the syringe body, even if it is not removed
from the protective sleeve, must be handled during use to
remove it from the outer housing after the cap is removed
from the housing. One also needs to handle the syringe body
in connecting it to the object into which the radioactive
substance is to be transferred.
The other type of packaging of which I am aware includes
a lead carrying housing having a cavity into which a glass
bottle, filled with the radioactive substance, is received.
The glass bottle has a screw-on cap associated with it, and
the carrying housing has a suitable lid associated with it.
This type of packaging is potentially more hazardous than
the previously mentioned packaging because it has no protec-
tive sleeve surrounding the bottle once it is removed from
the lead housing, and such removal is necessary in pouring
the radioactive substance from the bottle. This requires
that a person either directly handle the unshielded bottle
in removing it-from the housing and in removing its cap and
pouring the substance from the bottle or indirectly handle
the bottle through some type of mechanical manipulating
device, which type of device is likely less sensitive n its
control of the bottle than direct human handling would pro-
vide, whereby the contents of the bottle can be easily and
inadvertently spilled. Furthermore, such mechanical manipu-
lation devices are not always available at a well site where
radioactive tracer is to be transferred for injection into a
't ;~
well during a fracturing process, for example.
In view of the foregoing shortcomings of these two prior
art containers known to me, there is the need for a durable
safety container which is constructed and used in such a way
that inadvertent or unnecessary radioactivity exposure or
contamination of humans, equipment and the environment can
be avoided or minimized. Such a container should provide a
receptacle for receiving the radioactive substance and a
protective casing which is not to be separated from the
receptacle during normal usage. Such a container should be
designed so that minimal handling is required in either
charging or discharging a radioactive substance into or out
of the container. Such a construction minimizes the risk of
exposure or contamination of personnel, equipment and the
environment. Such a container should be constructed of com-
ponents that can be easily manufactured in compliance with
pertinent governmental regulations, such as those promul-
gated by the Department of Transportation. There is also
the need for an associated method of safely transferring a
radioactive substance with such a container.
Summary of the Invention
The present invention overcomes the above-noted and
other shortcomings of the prior art by providing a novel and
improved radioactivity shielding transportation assembly and
associated method of using the same. This assembly provides
a container which is constructed so that at most only end
caps are removed during usage of the assembly in either
loading or unloading the radioactive substance into or from
the container. This construction of the present invention
avoids or minimizes inadvertent or unnecessary radiation
exposure or contamination of personnel, equipment or the
environment. Other than the end caps, no other components
are separated during normal usage so that significant
shielding is maintained at all times. The container is
constructed so that it is readily connectible directly to a
complementally constructed receiver into which the radioac-
tive substance is to flow. The present invention can be
easily manufactured so that it complies with pertinent
governmental regulations. The present invention also provi-
des an associated method of transferring a radioactive
substance with such a container.
Broadly, the present invention provides a container in
which a radioactive substance is transportable, such as to a
location where the substance is to be moved into a receiver
apparatus (e.g., to a well site where the radioactive sub-
stance is a liquid tracer to be injected into the well
during a fracturing operation). The container comprises
reservoir means for holding the radioactive substance;
casing means, having the reservoir means disposed therein,
for providing a radiation shield about the reservoir means;
and coupling means for coupling the reservoir means and the
casing means directly to the receiver apparatus. In a pre-
ferred embodiment, the casing means includes side shield
means, having the reservoir means disposed therein, for
blocking radioactivity from passing beyond the side shield
means; top end shield means, directly releasably connected
to the side shield means, for blocking radioactivity from
passing beyond the top end shield means; and bottom end
shield means, directly releasably connected to the side
shield means, for blocking radioactivity from passing beyond
the bottom end shield means. In the preferred embodiment,
the side shield means includes a body, a portion of which
forms an alignment portion defining the coupling means.
In accordance with the method of the present invention,
a radioactive substance can be safely transferred by per-
forming the steps of moving the radioactive substance into a
reservoir housed within a prot~ctive radioactivity shielding
container; transporting the container, having the radioac-
tive substance stored therein, to a receiver into which the
radioactive substance is to be transferred; mounting the
container on the receiver; and moving the radioactive sub-
stance from the reservoir into the receiver withou~ removing
the reservoir from the container.
Therefore, from the foregoing, it is a general object of
the present invention to provide a novel and improved radio-
activity shielding transportation assembly and associated
method. Other and further objects, features and advantages
of the present invention will be readily apparent to those
skilled in the art when the following description of the
preferred embodiments is read in conjunction with the accom-
't.i`~'J~
Detailed Description of the Preferred Embodiments
Depicted in the drawings are two embodiments of anassembly constructed in accordance with the present inven-
tion. The assembly of each of these embodiments is general-
ly referred to and identified as a container 2 specifically
adapted for transferring liquid radioactive substances to a
receiver 4 [see FIGS. 9(e) and (f)]. In one specific contem-
plated use, the receiver 4 is a well head connection or a
mixing vessel found at, or transportable to, a well site.
Such a receiver 4 receives the radioactive substance and a
diluting fluid for blending with the radioactive substance
prior to injection of the blend into the well for use in
tracing fractures in a formation of the well (an example of
such a receiver is shown in a co-pending United States
patent application entitled "Multiple Reservoir Transporta-
tion Assembly for Radioactive Substances, and Related
Method" and assigned to the assignee of the present inven-
tion). Although the following description of these pre-
ferred embodiments will be made with reference to such usage
in the oil industry, the present invention is not limited to
such usage; rather, it is contemplated that the present
invention can be constructed for use with radioactive sub-
stances other than liquids and for applications other than
in the oil industry.
Broadly, the container 2 includes reservoir means for
holding the radioactive substance; casing means, having the
reservoir means disposed therein, for providing a radiation
1Li ij~ ,~",~j
shield about the reservoir means; and coupling means for
coupling the reservoir means and the casing means directly
to the receiver apparatus. The casing means more particu-
larly includes side shield means, having the reservoir means
disposed therein, for blocking radioactivity from passing
beyond the side shield means; top end shield means, directly
releasably connected to the side shield means, for blocking
radioactivity from passing beyond the top end shield means;
and bottom end shield means, directly releasably connected
to the side shield means, for blocking radioactivity from
passing beyond the bottom end shield means. Each of these
components of the assembly of the present invention will be
more particularly described hereinbelow with reference to
the first embodiment shown in FIG. 1 and the second embodi-
ment shown in FIG. 2. The method of using the assembly or
container 2 of the present invention will be described with
reference to FIGS. 8A, 8B and 9(a)-(j).
The reservoir means of the first embodiment shown in
FIG. 1 includes an elongated receptacle 6 having a port
member 8 extending axially therefrom. The receptacle 6 and
the port member 8 are specifically embodied in the construc-
tion shown in PIG. 1 by a commercially available plastic
syringe 10 having a syringe body 12 defining the receptacle
6 and further having a hollow needle 14 defining the port
member 8. The syringe body 12 has a longitudinal chamber
(of the type shown in FIG. 8A and identified by the refer-
ence numeral 16), which chamber has an open upper end and an
--10--
open lower end in fluid communication with the hollow por-
tion of the needle 14. The open upper end of the cavity is
encircled by a flange 18 which supports the syringe 10 in
the casing means of the container 2 as shown in FIG. 1.
In addition to the receptacle 6 and the port member 8,
the reservoir means includes suitable means for ejecting the
radioactive substance from the container 2. In the pre-
ferred embodiment shown in FIG. 1 (as well as for the embo-
diment shown in FIG. 2), this ejecting means includes a plug
20, having a tapered, frusto-conical lower end, to which
plug 20 another plug 22 and a plunger rod 24 can be con-
nected for slidingly moving the plug 20 through the cavity
of the syringe 10. These elements are illustrated in FIG.
8A. In these embodiments, these elements also define a
means for drawing the radioactive substance into the con-
tainer 2, and specifically into the chamber 16 of the
syringe 10, as will be more particularly described herein-
below.
The syringe 10 defining the reservoir means of the FIG.
1 embodiment is retained in the side shield means of this
embodiment, which side shield means is defined by an open-
ended cylindrical container body 26. The body 26 has a cen-
tral support portion or reservoir receiving portion compris-
ing an annular wall 28 made of lead (or other suitable
radiation shielding material). Extending longitudinally
(specifically, axially) through the wall 28 is a cavity 29
in which the syringe body 12 is received. The top end of
l~t> ~ ~ t:,,; !
the cavity through the wall 28 terminates adjacent a
shoulder portion 32, upwardl~ from which extends an annular
rim 34 integrally formed with the wall 28. When the syringe
10 is disposed in the cavity 29 through the wall 28, the
lower surface of the flange 18 abuts the shoulder surface 32
and the lower portion of the syringe 10 extends beyond the
cavity 29.
The body 26 also integrally includes an annular wall 36
which is radially outwardly offset from the wall 28. An
outer surface 38 of the wall 36 has a larger diameter than
an outer surface 40 of the wall 28, and an inner surface 42
of the wall 36 has a larger diameter than an inner surface
44 of the wall 28 defining the longitudinal cavity 29. This
inner surface 42 of the wall 36 defines a cavity 45 which
communicates with the cavity 29 and into which the needle 14
extends. This disposition of the needle 14 is concentric or
coaxial with the wall 36 in the FIG. 1 embodiment. This
wall 36, although being physically a part of the body 26,
defines the coupling means of the FIG. 1 embodiment and spe-
cifically provides an alignment portion or engagement por-
tion with which the container 2 directly couples with the
receiver, such as the receiver 4 schematically illustrated
in FIG. 9. The wall 36 extends longitudinally from the wall
28 in a direction opposite the direction of extension of the
rim 34 as is apparent in FIG. 1. The wall 36 extends from
the wall 28 by a length which is greater than the length the
needle 14 extends beyond the wall 28 ~so that the free end of
tlle needle 14 does not extend beyo~d the lower perimeter of
the wall 36.
To protectively close t~e ~wo open ends of the container
body 26, the container 2 includes the top and bottom end
shield means. In FIG. l, the top end shield means is de-
fined by a cylindrical lead cap 46 having a lower protuber-
ant portion 48 nesting within the rim 34 and having an area
engaging the top of the flange 18 to retain the syringe lO
securely against the side shield means. The engagement
between the cap 46 and the rim 34 can be by any suitable
means, such as by threaded coupling or frictional engagement
or otherwise, which provides an ade~uate retaining force so
that the cap 46 cannot be inadvertently removed or knocked
from the side shield means. This provides a suitable clo-
sure means for closing the top of the container 2 in a
manner by which radioactivity is shielded or otherwise pre-
vented from passing from beyond the top of the container 2.
The bo~-~om end shield means of the FIG. l embodiment
includes a cylindrical lead cap 50 having an annular wall 52
extending into the cavity 45, around the central region
thereof into which the needle 14 extends, when the cap 50 is
suitably attached to the alignment or engagement wall 38 as
shown in FIG. 1. The wall 52 has an outer diameter substan-
- tially the same as the diameter of the inner surface 42 of
the wall 36, and the wall 52 suitably couples therewith
through a suitable retention force whereby the cap 50 will
not be inadvertently removed from the container 2.
~; .
Disposed in the bottom of the cavity defined by the
annular wall 52 of the cap 50 is a suitable support means,
such as a rubber cushion 54, into which the free end of the
needle 14 is received when the cap 50 is attached to the
remainder of the container 2. This provides support for the
needle 14 during transportation. The cap 50, being con-
structed of lead (or other suitable radioactivity shielding
material), provides suitable radioactivity shielding.
The second embodiment, which is depicted in FIG. 2,
includes the same type of embodiment of the reservoir means
as the FIG. 1 embodiment, as indicated by the like reference
numerals used in identifying the syringe illustrated in FIG.
2. The side shield means of the FIG. 2 embodiment, however,
is constructed differently.
The side shield means of this second embodiment includes
a steel sleeve member 56 hav-ing two externally threaded end
portions 58, 60. Although shown threaded in FIG. 2, these
ends do not need to be threaded, but need to be constructed
for suitably releasably securing with the top and bottom end
shield means of this embodiment. Although the sleeve 56 has
been identified as being constructed of steel, it may be
constructed of any suitable material which provides adequate
strength so that the container 2 can meet any applicable
governmental regulations, such as those promulgated by the
Department of Transportation.
Forming another part of the container body of the second
side shield means embodiment is a radiation blocking member
defined by a molded lead wall 62 having a cavity defined
therein suitable for receiving the syringe 10. The wall 62
is fastened to the sleeve 56 by radially extending pins 64,
66 protruding into the wall 62 and welded to the sleeve S6.
As shown in FIG. 2, the wall 62 terminates short of the two
extreme ends of the sleeve 56 to define suitable hollow
regions 67, 69 in which the flange 18 and the needle 14 of
the syringe 10 can be respectively accommodated.
The top and bottom end shield means of this second embo-
diment are constructed of suitable pipe caps 68, 70 adapted
for coupling with the end portions 58, 60, respectively, of
the sleeve 56. To provide radioactivity shielding in the
caps, layers 72, 74 of lead are molded into the caps 68, 70,
respectively. The cap 68 is shown with a handle 76 by which
the container 2 can be conveniently carried or otherwise
moved when the cap 68 is affixed to the sleeve 56.
The coupling means of the FIG. 2 embodiment is defined
by the end portion 60 of the sleeve 56 whereby the end por-
tion 60 mates with a complementally formed portion of the
receiver, such as the receiver 4 depicted in FIG. ~.
Both of the embodiments shown in FIGS. 1 and 2 are de-
signed for easy fabrication. As mentioned, the syringe 10
is commercially available and thus does not need to be
specially manufactured. The elements of the casing means
and the coupling means of the first preferred embodiment are
readily molded using appropriately formed molds and molten
lead or other suitable radioactivity shielding material. No
-15-
machining or assembling of parts is thus necessary other
than as is needed to fit the syringe into the axial cavity
of the side shield means and to connect each of the end caps
as shown in FIG. 1.
The embodiment of FIG. 2 is likewise easily manufac-
tured. This embodiment is partially formed by using a two-
piece mold of the type shown in FIGS. 3-6. FIGS. 3 and 4
show a mold piece 77 which comprises a base 78 from which a
spacer 80 and a ~andrel 82 extend.
Another mold piece, shown in FIGS. 5 and 6 and identi-
fied by the reference numeral 83, has a base 84 from which a
spacer 86 extends. A central aperture 88 is defined for
receiving the free end of the mandrel 82 when the two mold
pieces 77, 83 are fitted together. The mold piece 83 shown
in FIGS. 5 and 6 also includes a port 90 through which air
is released when the mold pieces are positioned together.
Such proper posi~ioning of the mold pieces is illus-
trated in FIG. 7. First, the sleeve 56 is cut to the suit-
able length and its ends threaded or otherwise finished as
necessary. The side holes through which the retaining pins
64, 66 are inserted are cut through the sleeve 56 and the
pins 64, 66 are attached. The mold piece 77 is insert~d
through one end of the sleeve 56 as shown in FIG. 7, and
molten lead, or other suitable radioactivity shielding
material, is poured through the opposite end into the space
between the sleeve 56 and the mold piece 77 up to the
illustrated indentation formed in the thinner part of the
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-16-
mandrel 82. If needed or desired, the mold piece 83 is then
inserted through this opposite end of the sleeve 56 so that
the smaller diametered protuberant portion of the mandrel 82
is received in the central aperture 88 to maintain it in
proper alignment. After the molten material has hardened to
form the wall 62, .he mold pieces 77, 83 are then removed.
The molten shield material is also poured into the bottoms
of the two caps 68, 70 to form the respective protective
shielding layers shown in FIG. 2. To complete the assembly,
the syringe 10 is inserted into the cavity vacated by the
mandrel portion 82 and the two finished caps 68, 70 are
affixed to their respective ends of the sleeve 56.
Both of the described embodiments are used in a similar
manner to transfer a radioactive substance from one location
to another. With reference to FIGS. 8A and 8B, the method
by which the container 2 is charged, or filled, with the
radioactive substance (which will be described as a liquid
tracer suitable for use in a fracturing fluid for the exem-
plary use of the container 2) will be described. In FIG.
8A, the plug 20 is shown at the bottom of the chamber 16
within the syringe 10. With the plug 20 positioned at such -
a location relatively close to the needle 14, the other plug
22 and the plunger rod 14 are inserted through the open end
of the container 2, from which the top cap has been removed,
and down into the empty chamber of the syringe 10. The con-
tainer 2 is mounted on a suitable source of the radioactive
tracer in a position where the free end of the needle 14 is
--17 ~
immersed in the body of liquid tracer. The plunger rod 24
is then extracte~ or withdrawn upwardly, as viewed in FIG.
8A, away from the needle 14 whereby the coupled plugs 20, 22
are slid upwardly away from the former location of the plug
20 relatively near the needle 14 to a position farther from
the needle 14. This step of sliding the plug is continued
until the desired quantity of the radioactive substance is
received in the chamber 16 of the syringe 10. If the cham-
ber 16 is to be completely filled, the sliding step con-
tinues until the plug 20 is in the position shown in FIG.
8B, whereupon the plug 22 and the plunger rod 24 are de-
tached from the plug 20, thereby leaving the plug 20 within
the chamber 16 in sealing engagement with the syringe body
to retain the radioactive substance therein. These steps
accomplish the general step of moving the radioactive sub-
stance into the reservoir housed within the protective
radioactivity shielding container 2.
Once the container 2 has been adequately filled, the
container is transported, such as by a vehicle 92 illus-
trated in FIG. 9(a). In so transporting the container 2, it
is customary to ship several identical containers in a
packing carton of a suitable type, such as is schematically
illustrated in FIG. 9(b) and identified by the reference
numeral 94. When the container 2 reaches its destination,
it is unpacked from the carton 94 as illustrated in FIG.
9(c). At this time, the container 2 can be manually
handled, such as by a person using only protective gloves,
~ J~j
-18-
since the radioactive substance is protectively housed
within the fully assembled container 2.
In preparation for transferring the radioactive sub-
stance out of the container 2, the two end caps are removed
as depicted in FIG. 9(d); however, it is to be noted that
the syringe 10 remains fully retained in the side shield
means from which the two end caps have been removed. This
side shield means is then directly mounted on the receiver 4
in suitable alignment as established by the lower portion of
the container body. This mounting is depicted in FIG. 9(e).
In this position, the needle 14 is directly in communication
with the region of the receiver into which the radioactive
substance contained in the chamber 16 of the syringe body is
to be transferred.
To complete the transfer, the plug 22 and plunger rod
24, or a similar structure, are connected to the plug 20
through the end from which the top cap has been removed. A
downward force is applied to the plunger rod 24 to slide the
plug 20 through the chamber of the syringe body toward the
needle 14 so that the radioactive substance is ejected
through the hollow channel defined through the needle 14.
This is depicted in FIG. 9(f). Thus, the complete process
of charging the container 2 with the radioactive substance
and discharging the radioactive substance therefrom can be
safely performed with minimal risk of human or equipment or
environment exposure to, or contamination by, the radioac-
tive ssbstance.
--19--
Even after the radioactive substance has been dis-
charged into the receiver, there is minimal risk of external
contamination from the container 2 because the only compo-
nents which have been in contact with the radioactive sub-
stance are the syringe body, the needle and the plug, all of
which remain at all times housed at least within the side
shield means. After the step of moving the radioactive sub-
stance from the reservoir of the container 2 into the
receiver 4, these components are readily fully repackaged
within the full container 2 by reattaching the two end caps
[see FIG. 9(g)] to recomplete the assembly, as shown in FIG.
9(h). This reassembled container 2 is repackaged in the
carton 94 and reloaded onto the vehicle 92 for safe return
or disposal, as depicted in FIGS. 9(i) and (j).
From the foregoing, it is apparent that at no time is it
necessary in the use of the present invention for the
syringe containing the radioactive substance to be removed
from the side shield body. As a result, any radiation expo-
sure to an individual handling even the uncapped container 2
is intended to be low enough that the individual can safely
handle the assembly with only gloved hands; however, it
should be noted that as with any radioactive material, maxi-
mum safety precautions should be taken at all times. The
present invention does, though, provide a convenient assem-
bly by which a radioactive substance can be safely handled
without using possibly clumsy remote-controlled tongs or
other mechanical devices. Such mechanical devices, which
,,;r?,
-20-
are preferably used to handle the prior art screw-cap glass
bottles, can be difficult to control so that there is a
significant risk of spillage which could cause radioactive
contamination. The present invention is also preferable to
the lead-jacket-shielded prior art container used in the
medical industry because the jacket of such container is
easily removable and is not specifically adapted for both
retaining the reservoir and simultaneously coupling with a
receiver into which the radioactive substance is to be
transferred.
Thus, the present invention is well adapted to carry out
the objects and attain the ends and advantages mentioned
above as well as those inherent therein. While preferred
embodiments of the invention have been described for the
purpose of this disclosure, numerous changes in the con-
struction and arrangement of parts, and the performance of
steps, can be made by those skilled in the art, which
changes are encompassed within the spirit of this invention
as defined by the appended claims.
