Note: Descriptions are shown in the official language in which they were submitted.
5 2, 1 6 3
TITLE OF THE INVENTION
NUCLEAR WASTE PACKAGING MODULE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention generally relates to a module for packaging
nuclear waste OX various radiation levels which may be safely and
permanently buried it a waste disposal site.
Description OX the Prior Art
Various means for packaging nuclear wastes are known in the
prior art. One of the earliest types of packages used were
steel-walled, 55-gallon drums. Such drums were used in the early
"kick and roll" type waste burial systems. After they were
packed, the surface radiation of such drums was often too high to
allow them to be contact handled by human workers j accordingly,
the packed drums were handled by long boom cranes. These
cranes dropped the drums into a simple earthen trench, where
they were buried. Unfortunately, the use of such 55-gallon steel
drums in such trenches proved to be a highly unsatisfactory
method for the ground disposal OX nuclear waste. The loose
packed soil which these trenches were filled in with as much more
permeable to water than the densely-packed soil which formed the
trench sides, or the dense rock strafe which typically form the
trench bottom. Consequently, the relatively loose and water
permeable soil which SUP rounded the drums cause these trenches to
collect large amounts of standing water in what is known as the
"bathtub effect". This standing water ultimately caused the steel
walls of the drums buried within these trenches to corrode and
collapse. The collapsing drums and compaction of the soil over
time in turn resulted in a downward movement or subsidence of the
soil which caused a depression to Norm over the top of the trench.
This depression collected surface water Ed hence worsened the
tendency of the trench to collect and maintain pool of standing
water over the drums. The resulting increase in standing water
I
resulted in still more subsidence and accelerated the corrosion and
collapse ox the drums buried therein. The corrosion and collapse
of the drum containers at such sites has resulted in some
radioactive contamination OX the ground water flowing
there through.
To solve the problems associated with the drums used in such
"kick and roll" packaging and disposal systems, paclcages having
relatively thick, radiation-shielding and water-impermeable walls
were developed. In contrast to the thin walls of the Gwen
drums, the thick walls of these concrete packages reduced the
surface radiation of the resulting package to the point where they
did not have to be handled by long boom cranes, but could instead
be safely handled by human operators. Additionally, the thick
layer of concrete was much more resistant to degradation from
ground water. In use, these thick-walled concrete packages were
carried to the sites where waste was generated, which spas
typically a nuclear power plant. The waste was thrown directly
into the interior of these packages, and the packages were sealed
on-site. The seated packages were then carried to a remote
disposal site and burled. The low surface radiation associated
with these concrete packages allowed them to be stacked in an
orderly fashion within the burial trench by shielded forklifts.
Despite the superiority of such concrete packages over the
drum-type packages used in "kick and no lull systems I there are
still a number of shortcomings associated with this particular form
of packaging. first, these particular packages could not
conveniently handle high-level wastes, such as spent control rods;
the concrete walls of the packages were simply not thick enough to
reduce the surface radiation of the package to an acceptable level.
A second, related problem was that the surface radiation of the
resulting packages varied depending upon the scti~ity of the
particular waste packed therein. Since it is always desirable to
surround the "hottest" packages under the least active packages in
the burial trench, the fact that the surface radiation of these
particular packages varied over a broad range made it difficult to
ascertain the optimal order of stacking. Third, these packages
effectively had only a single radiation and water barrier between
the waste contained therein and the outside earth. If the concrete
walls of these packages became craclced or broken due to seismic
disturbance, there were no backup water or radiation barriers.
Fourth, these concrete packages were not conveniently recoverable
from the burial site. This last shortcoming is a particularly
serious deficiency if seismic disturbances cause a particular
package to crack or rupture to the point where radioactive matter
-may be leached out of it. The inability to selectively recover a
particular package may necessitate a massive digging-up and
relocation of the burial site.
Clearly, a need exists for a ground-disposable nuclear waste
package which is capable OX packaging radioactive waste OX varying
levels of radioactivity while presenting the same or at least similar
levels of surface radiation for such wastes. Ideally, such a
package should surround the waste contained therein with multiple
water and radiation barriers should the outside walls of the
package crack or break for any reason. Finally, the paclcage
should be stackable into a corlfiguration which is highly resistant
to damage from seismic events or other natural disturbances, and
should be easily recosrerable should any particular package in the
stack become damaged.
SUMMARY OF THE INVENTION
. .
In its most general sense, the invention it a ground
disposable module for encapsulating r~diaacti~re waste contained
within shipping containers in a structural stable form. The module
generally comprises a rigid outer container which provides a foist
r aviation and water barrier for the waste, an inner container
formed from the shipping container for providing a second
radiation and water barrier, and a central layer of fluent,
hard enable materiel, such as grout which twills the space between
the outer and inner con trainers . This central layer of grout
provides still another radiation and water barrier for the waste,
sod provide the McDowell with a structurally solid interior which
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reinforces both the compressive and tensile strength of the
resulting module.
The container of the module may hold a plurality of shipping
containers of redactor waste. Each of these containers may be
compacted in order to maximize the number of containers which
may be packed into the module container. Such compaction
increases the overall compressive strength of the module by
rigidifying the waste, and also renders the wastes less absorbent
to water and hence to leaching. In the preferred embodiment of
the invention, the shipping containers are subjected to a
compacting force which in elastically deforms both the shipping
container and its contents so as to avoid "spring-back" of the
compacted shipping container and its contents, which Gould result
in the formation of cracks or hollow cavities within the module if
I such spring back occurred while the grout were still in a plastic
state .
The compacted shipping containers my be centrally disposed
within the rigid outer container of the module in order to equalize
- the surface radiation of the resulting module. Additionally, the
2 0 number OX shipping containers grouted within the rigid outer
container may be chosen so that the surface radiation of the
resulting module does not exceed a preselected limit. In order to
facilitate the handling of the module, the bottom portion of the
outer container of the module may include a pattern of
substantially parallel grooves or receiving the forks of a forklift,
end the top portion of this container may include a plurality of
I-bolt anchors detachably connectable to the hoots of a hoist.
Additionally, the rigid outer container may include a slab-type lid
having at least one lid-securing member which is insertable with
I the grout when the grout is in a non-hardened state, which serves
to anchor the lid to the outer container when the grout hardens.
Finally, the shape of the rigid outer container of the module
is preferably a right-angled prism having a plurality of side walls
of equal size and shape in order that the modules may be solidly
stacked in mutually contiguous columns. In the preferred
embodiment, the modules are hexagonal prisms. The
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subsidence free solid-paeked array which such hex~gonQI prisms
afford has sufficient compressive strength to support an
earth-type trench cap, yet is flexibly conformable to changes in
the shape of the trench caused by seismic disturbances or other
natural disruptions.
BRIEF DESCRIPTION OF THE SEVERAL FIGURES
Figure 1 is a perspective, queue view of the packaging
facility used in the system of the invention j
Figure 2 is a perspective, cutaway view of the high-force
1 p compactor used in the packaging facility illustrated in Figure 1;
Figure 3 is a perspective, cutaway view of the disposal site
of the invention;
Figure PA is a top, plan view of the packaging module of the
invention;
Figure 4B is side, partial cross-sectional view of thy
module;
Figure I is bottom view of the module of the injection
Figure PA is a top view of the cap of the module of the
invention;
2 0 Figure SUB is a side, partial cross-sectional Roy OX the cap
illustrated in Figure PA;
Figure 6 is a perspective Roy of a packed arid sealed module
of the invention, and
Figure 7 is a perspective, cutaway view of a pocked module
2 5 of the invention .
DETAILED DESCRIPTION OF THE PREFERRED Embodiment
.
with reference now to Figure 1, wherein like reference
numerals designate like components throughout ~11 of the severely
figures, the paclsagin~ facility 1 of the system of the invention
generally comprises four isolation walls pa, 2b, 2c and Ed which
enclose a remote handled waste p~c~agin~ section 3 on the left side
of the building, a module loading and transportation section 60 in
the center of the building, and a contact handled waste section 85
on the right side of the building. Both the remote end contact
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handled waste sections 3 and 85 include a drive-through 7 end 87,
respectively. At these drive-throughs 7 and 8q, trucks 13 and 95
deliver remote and contact handled nuclear waste in relatively
lightweight shipping containers Rio e ., lowlier , 55-gallon drums , and
LEA containers) from remotely located waste generating sites for
encapsulation into the relatively heavy, solidly packed modules
200. In the preferred embodiment, the final disposal site 150 of
the modules 200 packed by the packaging facility 1 is located in
close proximity to the facility 1 in order to minimize the distance
which the packed modules ~00 which may weigh o'er 30, 000
pounds) must be transported. At the outset, it should be noted
that there are at least three major advantages associated with a
facility surrounded by isolation walls which is remotely located
from the waste-generating sites, yet is close to a final disposal
site 150. First, there is no need to transport the relatively heavy
modules 200 to the waste generating site. Second, the possibility
of the waste-generating site from becoming contaminated prom a
packaging accident is eliminated. Thirdly, the isolation walls I
2b, 2c and Ed minimize the possibility of the disposal site 150
becoming contaminated from any packaging accidents.
Turning now to a more pesky description of the
remote-handled waste section 3 of the facility 1, this section 3
includes a driveway 9 having all entrance (not shown end an exit
11 for receiving a delivery truck 13. Such trucks 13 will normally
carry their loads of nuclear waste in a reusable, shielded
shipping cask 15 of the type approved by the U . S . Department of
Tr~sportation or the U . S . Nuclear Regulatory Commission.
Disposed within such shielded shipping Cassius 15 are metallic or
plastic liners snot shown) which actually hotel the wastes. Section
3 of the facility 1 further includes a processing platform 18 which
is about the sane height as the height of the bed of the truck 13,
a shield bell 19 having a hook assembly 217 and a
remote-controlled traveling crane 23. The shield bell 19 is
preferably formed from a steel shell ha vying a lead liner which is
thick enough to reduce the amount of radiation emanated frailty the
non-contact waste to an acceptable level. The crane 23 includes a
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primary hoist 25 detachably connectable to the hook assembly 21 of
the shield bell 19 via an electric motor-operated pulley assembly
27. The traveling crane 23 further include a carriage I for
moving the primary hoist 25 in the "X" direction (parallel to the
driveway 9 of the drive-through 7), as well as a trolley 33 for
moving the primary hoist 25 in a "Y" direction (parallel to the
front face of the facility 1 ) . The vertically adjustable, electric
motor-operated pulley assembly 27, in combination with the
carriage 29 and trolley 33, allows the traveling crane 23 to swing
the shield bell 19 o'er the shipping cask 15 of the delivery truck
13, pick up the waste-containing liner out of the cask 15, and
place the liner at a desired position onto the processing platform
18. Although a remote-controlled traveling crane 23 operated via a
T.V. monitor is used in the preferred embodiment, any number of
other types of existing remote-controlled crane mechanisms may be
used to implen7ent the invention. In addition to primary hoist 25,
secondary hoist 35 is also connected between the traveling crane
23 and the shield bell 19. The secondary hoist 35 controls the
position of a cable and hook (not shown) inside the shield Ted 19
which is capable OX detachably engaging the waste-containing liner
disposed within the shielded shipping cask 15.
The remote-handled waste section 3 of the building 1 further
includes a characterization station 37 having various radiation
detectors 39 and ultrasonic detectors 41 for verifying that the
contents of the liner inside the skipping cask 15 conform to the
shipping manifest. The radiation detectors 39 are used to measure
the intensity of the radiation emanating from the waste contained
in the liner and to check the "signature" of the radiation spectrum
of this waste to confirm the accuracy of the shipping manifest.
The ultrasonic detectors 41 are used to determine whether or not
any radioactive liquids are present within the liner. Federal
regulation strictly prohibit the Burr of radioactive wastes in
liquid Norm; consequently, the information provided by the
ultrasonic detectors 41 is of paramount importance. Both ho
radiation detectors 39 and ultrasonic detectors 41 are electrically
connected to a bawls of read out dials 45 by mean of cable
I
disposed in grooves I in the processing platform 18. Although
not specifically shown in my of the sever figures, the outputs of
the radiation detectors 39 and the ultrasonic detectors 42 are
preferably fed into a central computer both for record-keeping
purposes, and for determining how much of a particular kind of
waste can be loaded into a particular module before the surface
radiation of the module 200 exceeds a preselected limit. The
central computer can further compute how much grout must be
poured into a particular loaded module in order to properly
encapsulate the wastes, and has the capacity to actuate an alarm
circuit hen the ultrasonic detectors 41 indicate that an
unacceptable percentage of the wastes contained in the liner are in
liquid form.
In the preferred embodiment, the height of the processing
platform 18 is chosen to correspond appro~irnately with the height
of the bed of a trailer truck 13 so that any human operators who
may be present on the platform 18 when the lid is removed from
the cask 15 will not be exposed to the radiation beaming out of the
top of the cask. In operation, the shield bell 19 is towered into
the open cask 15, engages the liner contained therein, end then is
swung over the sensors 39 end 41 of the characterization station
37 and quickly lowered to within a few inches of these sensors to
minimize any of the exposure ox section 3 to any radiation
beaming out from the bottom of the shield bell lo which reflects ox
of the platform 18. In the preferred embodiment, the processing
platform 18 is formed from A solid slab of concrete both for the
structural solidarity of the facility 1 as a whole, as jell us for
shielding purposes. This last purpose will become clearer after
the structure and function of the lag storage wells 50 is explained
hereinafter. While the characterization station 37 of the preferred
embodiment includes only radiation detectors 39 sod ultrasonic
detectors 41 and other types of detectors (such fly rerun T. V.
monitors for visually identifying the waste may also be included if
desired .
3 5 Finally, the remote-h~dled waste section 3 of the facility
includes four lag storage wells 5û, a well as a remedial suction
I I
Rowley 53 formed from shielded walls 54 and accessible through
shielded doors 55. Each of the lay storage wells 50 includes a
generally cylindrical well topsoil by a disk-shaped coyer. The lag
storage wells 50 provide a safe and convenient storage are for
nuclear waste shipments in which the characterization station 37
has detected the presence of liquids in excuser quantities or
other unacceptable conditions. Additionally, the lag storage wells
may be used to temporarily store shipments of remote-handled
wastes when the grouting station l18 becomes backed up. The
materials and thickness of the disk-shaped cap which tops the
wells So are chosen so as to r educe the amount OX radiation beamed
into the working area of section 3 from the remote handled wastes
storable therein to within a safe laurel. The remedial action room
provides a separately contained area within the remote handled
section 3 of the facility 1 where broken liners (or liners containing
liquids) may be properly repaired or treated without any danger of
contaminating the main portion of the remote ken died sectiorl 3, or
the facility 1 at large. As vowel become more evident hereinafter,
the provision of a separately contained room 53 to repair the
broken walls of a liner is important because the walls of the liner
provide one of the three radiation and water barriers within a
module 200 when the liner is grouted within one of these modules.
When free liquids are found within the waste liners, the remedial
action room 53 provides a contained area where the liquid may be
mixed with suitable absorbents or other solidification media so as
to bring it into a solid form acceptable for burial within the
purvies~r of present federal regulations. Under normal
circumstances, neither the lag storage wells 50 nor the remedial
action room 53 is used to process the remote handled wastes.
Instead, after the characterization tests are completed, these
wastes are usually remotely hoisted through the labyrinth exit 56
formed by shield walls aye, 57b which Norm the back of section
and placed into a module 200 on a rail cart 64 en route to the
grouting station 118.
The module loading an transportation section 60 is centrally
located within the facility 1 between the remove handled section 3
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and the keynote handled section 85. The central location of the
module loading and transportation section 60 allows it to
conveniently serve both the contact and remote handled sections 3
and 85 of the facility 1. Cienerally, the module loading and
transportation section 60 includes a conventional traveling crane 62
(which includes all the parts and capacities of previously described
traveling crane 23) for loading modules 200 which are stacked
outside the building 1 onto rail carts 64. These rail carts 64 are
freely movable along a pair of parallel loading rail assemblies aye
and 66b. In order to render the rail carts 64 framing, the
beds aye and 70b onto which the tracks aye and 68b are mounted
are slightly inclined so that the carts 64 engaged onto the tracks
aye and 68b of the loading rail assemblies aye Ed 66b will freely
roll down those tracts by the force of gravity. While not shown in
any of the several figures, each of the loading rail assemblies aye
and 66b includes a plurality of pneumatically-actuated stopping
mechanisms for stopping the rail carts 64 at various loading,
grouting and zapping positions along the loading rail assemblies
aye and 66b. The module loading and transportation section 60
includes a return rail assembly 74 having a bed 78 which is
inclined in the opposite direction from the beds aye and 70b of the
loading rail assemblies aye and 66b. The opposite inclination OX
the be 78 of the return rail assembly 74 allows the rail carts to
freely roll on the tracks 76 by the force of Grosset brick to a
loading position in section 60 after a grouted and capped module
200 has been removed therefrom. Finally, a shield wall 79 which
is preferably formed from a solid concrete wall at least lo inches
thwack is placed between the rail assembly aye end the return rail
assembly 74 in order to shield the contact section 85 from any
exposure from the remote-handled wastes contained within the
shield bell 19 as they are loaded into one of the modules 200 and
grouted. This shield wall 79 generally serves the dual function of
allowing a contact handled waste section 85 Jo be enclosed within
the same facility as the remote handled waste section 3, arc
allowing the use of a common module loading and transportation
section 60 for both the remote and thy contact handled sections 3
I
and 85 of the facility 1. This last advantage avoids the pro-
vision of duplicate loading and transportation systems.
Turning now to the contact-handled waste section 85, this
section of the facility 1 includes many of the same general
components present in the remote handled section 3. For example,
section 85 includes a drive-through 87 including the same sort of
driveway 89, entrance 90 and exit (not shown) previously disk
cussed with respect -to drive-through 7. Section 85 also includes
a processing platform 93 preferably formed from a solid slab of
concrete which rises to approximately the same height as the
bed of a truck so as to facilitate the unloading of the packaged
wastes from the delivery truck 95. Section 85 also includes a
pair of characterization stations aye and 107b. Finally,
section 85 includes a remedial action room 112 or repairing
broken containers, and converting liquid and other improperly
packaged wastes into an acceptable solid form for burial.
However, despite these common components with section 3,
section 85 includes some other components which are unique in
the building 1. For example, a relatively light-duty jib crane
99 having a magnetic or vacuum hoist 101 is used in Lyle ox the
relatively heavy traveling crane 23 of section 3. Because the
wastes which are processed in section 85 are of a sufficiently
low radiation level so that they may be directly contacted by
human workers, there is no need for a crane capable of lifting
the heavy shield bell 19 used in section 3. Consequently, the
crane used in section I need only be capable of lifting lightly
packaged nuclear wastes, which typically arrive at the building
1 in 55-gallon steel drums 97~ Although some light shadow
shields may be used on the contact able section I of the building
1, the generally low radiation level of the wastes processed in
this area obviates the need for heavily shielding each of steel
drums 97 containing the wastes. Therefore, a conveyor system
103 preferably formed from rollers is provided which greatly
facilitates the handling of the drums 97 in which the wastes
are contained. Finally, a high-force compactor 110 is
provided which not only compacts the wastes into a smaller
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volume, but squeezes the surrounding drum down to a point so far
above the inelastic limit OX the steel that the wastes are incapable
of "springing back" in volume during the grouting process. This
is an important advantage which will be elaborated on at En later
S point in this text.
The conveyor system 103 includes both a pair of serially
arranged compactor conveyor belts aye and 105b, as welt as a
remedial action conveyor belt 106. Compactor conveyor belt aye
conveys the 55-gallon drums 97 containing the contact-handled
waste from the jib crane 99 through a first characterization station
aye which includes ultrasonic and radiation detectors (not shown),
and into the loading mechanism 110.1 of the high-force compactor
110. The high-force compactor 110 applies a pressure of between
500 and 1,10~ tons to the 55-gallon drum containers, thereby
reducing them into high-density "pucks" 117 having a density of
between 60-70 Ibs./cu. ft. In the preferred embodiment, a
compaction force of 600 tons is typically used. The high-density
pucks 117 are ejected from the high-force compactor 110, and slide
down a ramp 111~2 onto compactor conveyor belt lost, which in
turn facilitates the movement of pucks 117 through a second
characterization station 107b which is likewise equipped with
ultrasonic and radiation detectors (not shown. The conveyor belt
105b then conveys the high-density puck 117 to the magnetic or
vacuum hoist 116 of a jib crane 11~, which swings the puck 11~
over into a module 200 en route to the grouting station 118. The
remedial action conveyor belt 106 comes into play when the
characterization station aye detects that pa) the drum 97 contains
a liquid, (b) the walls of the drum 97 are broken, or I the
waste contained within the drum 97 is not compressible. If any of
these three conditions are detected, a human operator (not shown)
merely pushes the drum 97 from the coss~pactor conveyor aye onto
the remedial action conveyor belt 106, which in turn conlreys the
drum 97 to the remedial action wrier where appropriate
wall-repairing, lulled solidification, or separate in-drum grouting
procedures are undertaken in order to put the drum 97 and its
contents in proper condition for encapsulation within a module 200.
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In the event there is a bncl~-up condition in the remedial action
room 112, the drum 97 may be temporarily stored in the lag
storage wells 113 of the contact handled section 85.
Wit specific reference now to Figure 2, the high-force
compactor 110 of the invention includes a loading mechanism 110.1
having a drum scoop 110.2 at the end of an articulated,
retractable arm assembly 110 . 3 as shown . Drums 97 sliding down
the chute at the end of the compactor conveyor aye are fed into
the drum scoop 11û.2 by a human operator. The articulated,
retractable arm assembly 110.3 then loads the drum 97 into a
loading cradle 110.4. The compactor 110 further includes a
loading ram 110.5 which feeds the drum 97 into a retractable
compaction cylinder 110 . 6 which is movable between a position
outside the main ram 110 . 8, and the top of the ejection ramp
111.2. In Figure I the compaction cylinder 110.6 is illustrated in
its extended position Sue from the main ram 110 . I, and adjacent
the top of the ejection ramp Ill. 2 . After the drown 97 is loaded
into the compaction cylinder 11û.6, the cylinder 110.6 is retracted
into the main ram 110. 8, where the drum 97 is crushed between
the ram piston 110 . 9 (not shown), and the bed of the main fern
111.8. As previously mentioned, a compaction force of between
500 and 1,100 tons is applied to the drum 97. There are three
distinct advantages associated with the use of such a high
compaction force. First, the consequent reduction in volume of
the drum 97 and its contents allows many more drums to be packed
inside one of the modules 200. Specifically, the use of such a
high compaction force allows thirty five to eighty-fou1 drums 97 to
be packaged inside one of the modules 200~ instead of fourteen.
Secondly, and less apparent, the use of such a high compaction
force deforms the steel in the drums 97 as tve11 as the waste
contained therein well beyond the inelastic limits of the materials,
so that there is no possibility that the resulting, high-density
pucks will attempt to spring back" to a larger shape after they
are ejected from the ejection r~mF~ 111. 2 . The elimination of such
US roping back" eliminate the possibility of cavities or intern
cracks forming within the hardening grout in the module 20û after
the module 200 is loaded with pucks 117 and grouted. Far from
"springing back", the resulting hedonist pucks 117, when
covered with grout, form a positive, non-compressible reinforcing
structure in the interior OX the module 200 which assists the
module in performing its alternative function as a structural
support member for the earthen trench cap 164 which is applied
over the disposal site 150. Finally, such extreme compaction of
the waste inside the drums 97 ( which is typically rags, paper and
contaminated uniforms) renders them resistant to the absorption of
water. This, of course, makes them less prone to leaching out
radioactive material in the remote event that they do become wet.
Such resistance to water absorption also renders the wastes less
prone to biodegradation which again complements the overall
function of the module 200 in encapsulating the wastes I since such
biodegradation can over time "hollow ought the vessel carrying the
waste, end result in subsidence problems.
In closing, it should be noted the compactor 110 includes an
air filtration system 111.~ having a filter 111.5, a blower assembly
111.6, and an exhaust stack 111.7. The air ~ltration system 111.4
2 0 draws out any redactor, airborne particles produced as a result
of the application of the 660-l, Lou ton force onto the drum 97
carrying the contact able waste.
Turning back to Figure 1, section 85 of the facility 1 includes
a grouting station 118 having an extendible trough 120 capable of
pouring grout moo a module 200 on rail carts 64 engaged to either
rail assembly aye (adjacent the remote handle waste section I or
rail assembly 66~ ( adjacent the contact-handled waste section 85) .
The use of a single grouting station 118 for modules 200 loaded
from both the non-contact and contact handle sections 3 and I
again avoids the duplication of expensive components in the overall
system. Just beyond the grouting station 118 is a capping station
122 including a traveling crane 126 having a hoist 128 for lifting
the lids 220 over the tops of the module 200 incident to the
capping process. A more precise description of the capping
3 5 process will be given when the structure of the modules 200 is
related in detail.
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While the modules 200 are normally filmed with waste! grouted
at the grou~mg station 118 and capped at the waste packaging
solute 1 located near the waste disposal site 15û, they may also
be processed a the facilities of the generator of the waste. Since
the surface radiation of the resulting modules is generally low
enough for contact handling, the wastes in the modules 200 may be
conveniently stored onset pending the availability of disposal
space. When disposal space is available, the modules 200 may be
transported in reusable transpiration overpack (not shown) to the
disposal site 150 and stacked directly into the trenches 152. While
this method is not preferred it is usually less expensive than
using the onset waste storage facilities.
Figure 3 illustrates the disposal site 150 used in conjunction
with the packaging facility 1. The disposal site 150 generally
comprises a trench 152 (or a plurality of parallel trenches having
a generally flat, alluvial floor 15~. Before the trench is loaded
with capped modules 200 in which the grout has hardened, a
plurality of water-col~ecting lysimeters 155 are uniformly placed
throughout the floor 154 in order to monitor the radiation level of
2 0 water in the trench . The Iysimeters 155 are placed in the trench
floor 154 by auguring a hole in the floor, and inserting the
elongated bodies of the Iysimeters 155 therein. A network of
plastic tubes (not shown ) enables the operators of the disposal site
15û to periodical dray out any water that has collected in the
cups of the lysimeters 155. The radiation level of these skater
samples is periodically monitored to determine whether or not any
radioactive substances have somehow been leeched from the
modules 200. After the Iysimeters 155 have been properly buried
throughout the floor 154, the poor 154 is covered with a travel
layer 156 about two feet thick, which cots as a capillary barrier.
Even though the disposal site 15~ i preferably selected in an urea
where all flow of ground water would be at least 80 feet below the
trench floor 154, the gravel capillary barrier 156 is placed over
the top of the floor 154 to provide added insurance against the
seepage of ground water into the stacked array 160 of modules 200
by capillary action prom the trerlch poor 154. While all of the
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capillary aurora, in the disposal iota 150 of the invention are
preferably formed of gravel, it should be noted that the invent lion
encompasses the use of any coarse, granular substance having a
high hydraulic conductivity. The layer of gravel 156 is covered
with a coxed zone so sand 158 approximately four inches thick.
This choked zone of sand 158 acts as a road bed for the wheels of
the heavy forklifts 185 and trailers 184 which ore used to
- transport the modules 200 to the trench 152. If the zone 158 were
not present, the wheels of these vehicles 184, 185 would tend to
sink into the gravel layer 156.
The next component of the disposal site 150 is the solidly
packed array 160 of hexagonal modules 20U illustrated in Figure 3.
In the preferred embodiment, the modules 200 are preferably
stacked in mutually abutting columns, with each of the hexagonal
faces of each of the modules 200 coplanar with the hexagonal fuses
of the other two modules forming the column. The arrangement of
the modules 200 into such mutually abutting columns results in at
least four distinct advantages. First such solid packing of the
modules 20û provides a support structure for the nonrigid trench
cap 164 which may be quickly and conveniently formed prom
natural, fluent substances such as soil, sand and gravel. Second,
such an arrangement is almost completely devoid of any zaps
between the modules 200 vhich could result in the previously
discussed soil subsidence problems. Third, such an arrangement
could weather even severe seismic disturbtmces, since each of the
modules 200 is capable of individual, differential movement along
eight different planes (i.e., the top, bottom and six side surfaces
of the hexagonal prisms which form the modules 200). Because
none of the riddles are rigidly interlocked it any of the
adjacent modules, each of them is capable of at lest some vertical
and horizontal sliding movement in the event of a seismic
disturbance. Such an eight-pla~e freedom of movement renders
the entire muddle array 160 flexibly conformable with change in
the shape of the trench 152, and eliminates or sty least minimizes
the probability of a local seismic disturbs creating local stress
points in the array 160 what are powerful enough to rapture or
1 7
crack the walls of individual containers. Fourthly, the columnar
stacking used in the array 160 mikes it easy to recover a
particular module 200 in the event that such r recovery becomes
desirable, since any one of the modules 200 may be withdrawn from
the trench by digging a single, module-wide hole over the
particular column that the desired module is included within. In
the preferred embodiment, the most radioactive or outstay" of the
modules ~00 is placed on the bottom layer of the module array 160
and surrounded by less radioactive modules so that the
surrounding module;, and the middle and top module layers will
provide additional shielding from the radiation emanating from the
materials in the "hot" modules.
The trench 152 further includes side gravel capillary barriers
aye and 162b which are positioned between the sides of the solid
module array 160, and the walls of the trench 152. Again, the
purpose of these barriers aye and 162b is to prevent July seepage
of water from being conducted from the sides ox the trench 152 to
the sides of the solidly packed array 160 of modules 200. In the
preferred embodiment, each of these side capillary barriers aye
and 162b is about two feet thick.
The trench cap 164 is preferably a non-rigid cap formed from
fluent, natural substances such as soil, sand and gravel. Such a
cap 164 is more resistant to seismic disturbances than a rigid,
synthetic structure would be. Specific, the non-rigidity of the
cap 164 makes it at least partially "self-healing" should any seismic
disturbance net to vertically shift the various layers of the cap 164
small distances from one another. Additionally, in the event of a
severe seismic disturbance which does succeed in causing
considerable damage to the cap 164) the cap 164 may be easily
repaired with conventional road building and earth moving
equipment. As was previously indicated, the solidly packed array
of modules 160 provides all of the structural support needed to
construct and maintain the various layers OX the trench cap 164.
The first layer of the trench cap 164 is preferably a layer ox
alluvium 166, which should range from between our feet thick on
the sides to seven feet thick in the center. As is indicated in
I
Figure 3, the alluvium layer 166 ( which is preferably formed from
the indigenous soil vouch was removed in creating the trench 152)
gradually slips away from the center line of the layer at a grade
of approximately 4.5%. Such a contour allows the cap 1~4 to
effectively shed the water which penetrates the outer layers of the
cap lS4, and to direct this waxer into side drains aye and 178b.
After the alluvium layer 166 is applies over the top of the solidly
packed module array 160, the layer 166 Is compacted before the
remaining layers are placed over it. Such compaction may be
effected either through conventional road bed compacting
equipment, or by merely allowing the alluvium m the layer 166 to
completely settle by natural forces. OX the two ways in which the
alluvium in the layer 166 may be compacted, the use a road bed
compaction equipment is preferred. oven though the natural
settling time of the alluvium in the invention is very fast no
compared to the settling times of soils used in prior art disposal
sites, it is still rarely shorter than three months, and may be as
long as one year, depending upon the characteristics of the
particular soil forming the alluvium. By contrast, if road
compaction equipment is used, the settling time may be reduced to
a matter of a few days. It should be noted that the alluvium layer
166 is placed over the solidly puked art a 160 at approximately
the same rate that the array 160 is ruled by stacking the
individual modules 200. Such contemporaneous placement of the
alluvium layer 166 o'er the muddle array 160 minimizes the amount
of radiation which the trerlch workers are episode Jo as the
disposal site 15û is formed.
After the alluvium layer 166 has been appropriately
compacted, a choked zone of sand 168 of approximately four inches
in thickness is applied over it. After the salad layer 168 has been
completely applied over the alluvium layer 166, another gravel
capillary barrier 170, approximately two feet in depth, is placed
over the Tuesday sand layer 168. The choked sand layer 168
serves as an intrusion barrier between the relatively coarse gravel
forming the gravel capillary barrier 170, and the relatively finer
alluvium in the alluvium layer 166. Once the gravel capillary
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barrier 170 h&s been laid, another choked zone of sand 172,
approximately four inches in thickness, is applied over the gravel
capillary barrier 170. Next, a layer of fine, water shedding silt
164 is applied over the choked zone of sand 172 overlying the
gravel capillary barrier 170. Again, the choked zone OX sand 172
serves as an intrusion barrier between the silt in the silt layer
174, and the gravel in the gravel capillary barrier 170. The silt
layer 174 is the principal water-shedding layer of the trench cap
164, and is approximately two feet thick, and formed from sized
material (preferably obtained locally) which is compacted in place.
The use of a silt layer 17~ in lieu of other water-shedding natural
mutters, such as clay, is advantageous Lo it least two respects.
First, silt is often more easily obtainable locally than clay, and
hence is less expensive. Secondly, if the silt layer 17~ should
become saturated with water, it will not tend to split or crack
when it dries out as clay would. The absence of such splits or
crocus helps maintain the overall integrity of the trench cap 164.
The side edges of the silt layer 174 terminate adjacent to the
pair of French drains aye and 178b located on either side of the
trench 152. The French drains byway and 178~ include a trench in
which perforated pipes guy end 18~b are laid. Utter flowing
down the sides of the silt layer 174 will float through the
perforations in the pipes aye and 182b and flow along the drain
trenches aye and 180b, away from the trench 152. In the event
that the rains or other source of surface water becomes so severe
that the silt layer 174 becomes completely saturated with water,
the gravel capillary barrier 170 will prurient any water from
migrating down from the saturated silt layer 174 into the module
array 160 via capillary action.
The top and final layer 176 of the trench cap 169 consists of
graded rip-rap which in more colloquial terms, is very coarse
gravel (which may be as large as boulder sized. The rip-rap
layer 176 performs at least three functions. First, it insulates the
silt layer 17~ from potentially erosive winds and running water.
Second, it provides a final radiation barrier against the module
array 160 which brings the radiation level of the disposal site 150
-20- I
down to well within the range of normal background radiation.
Third, it provides an intrusion barrier which discourages would-be
human and animal intruders from digging up the ground above the
module array 160~ The preferred embodiment of the cap 164 as
heretofore described is for arid regions. In humid regions, an
alternative embodiment of the cap 164 would comprise a first water
infiltration barrier of native soil over the solid array 160 of
modules 200. This layer in turn would be cowered by a sand rid
gravel capillary barrier similar to the previously discussed layers
168, 170 and 172. These sand and gravel capillary barriers would
in turn be covered by a bio-intrusion layer of cobble, and topped
by additional sand and gravel layers for supporting a final layer
of soil having a vegetative cover. in such an alternative
embodiment, the vegetative cover serves both to prevent any
erosion which might occur on the upper layer of soil, and also
removes water which infiltrates the top layer of the cap. The
vegetation used should have shallow roots in order aye the
integrity of the cap 164 will not be violated. Additionally, such
an alternative embodiment might have if steeper slope of perhaps
2 0 10 or more because of the greater amount OX rainfall associated
with such regions.
With reference now to Figures PA, 4B, 4C and PA, 5B, the
module 200 of the invention generally consists of a container 201
having reinforced concrete walls and a lid 220 which caps the
2 5 container 2û1 after it is filled with nuclear wastes and properly
grouted .
With specific reference now to Figures PA through 4C s thus
container 201 of the module 200 is a hexagon~lly~shaped prism 202
having a cylindrical interior 21B. The corners 204 where the
3 o hexagonal walls abut one another are preferably truncated so that
small gaps Fiji be left between abutting modules 200 when they are
stacked in the module array 160 illustrated in Figure 3. These
small spaces are large enough to receive recovery tools (should the
recovery of any one of the modules 200 become elesirable3 but are
small enough so that no significant amount of soil subsidence Wylie
cur when the modules 200 are arra3lged in the configuration
it
Lo I
--21--
illustrated in Figure 3. Further, the truncated shape of the
corners 20~ renders these corners less vulnerable to the chipping
or cracking which could otherwise occur when the forlclift 185
pushes the module 200 into the module array 160 incident to the
stacking process .
Turning now to the top and bottom portions of the containers
201 of the modules 200, the top portion 206 is opened as shown to
permit the loading of nuclear waste and grout. The top portion
206 includes three I-bolt anchors aye, 208b and 20~c which allow
l O the container 201 to be handled by the grappling hooks of the
cranes in the packaging facility 1 and stacked into the trench 164.
Alternatively, these anchors aye, 208b and 208c allow the modules
200 to be lifted out of the trench 164 if recovery is desired. The
shflnks of the anchors aye, 208b and 208c are deeply sunken into
the concrete walls of the container 201 as indicated in order to
insure an adequate grip thereto. The bottom portion ~09 of the
container 201 includes the bottom surface 210 of the interior of the
container 201, and an outer surface 211 having a pattern of
grooves 212. Each of these grooves are slightly deeper and wider
2 O than the forks of the shielded forklift 185, so that these grooves
21~ greatly facilitate the handling of the module 200 by the forklift
185. The galore pattern of the grooves 212 also allows sunk a
forklift to engage a particular module from a variety of different
angles, which further facilitates the handling of the modules.
Reinforcing the concrete walls and bottom portion of the container
201 of the module is if basset" 215 wormed from commerci~ly
available, steel-Ieinfol cuing mesh. The basket ~15 greatly increases
the tensile strength of the walls and bottom portion 209 of the
container ~01 of the module 200. In the preferred embodiment the
walls of the container 2Q1 are at yeast three inches thick.
Additionally, the cylindrical interior 216 of the container 201 is at
least severlty-five inches in diameter in order that fourteen drums
or seven stacks of high-density pucks :L17 may be stacked within
the cylindrical interior 216 of the container ~01. The top portion
20~ of the container 201 includes a plurality of groves 214~, ?14b,
214c, 214c3, eye and 214f for receiving the cap-securing rods
-22-
aye, 232b, 232c, 232d, eye and 232f of the slMb-type container
lid 220, which will be presently discussed on retail.
With reference now to Figures SPA and SUB, the slab-type
container lid 220 generally includes a disk-shaped upper section
222, and an integrally formed, disk-shaped Louvre section 228 which
has a slightly smaller diameter. The edge of the upper section 222
is flattened in three sections 223.1, 223.2 and 223. 3, which aye
spaced approximately 120 from one another. Y1hen the container
lid 220 is properly placed over the open top portion 206 of the
1 0 container 201, these flattened sections 223.1, 223.2 and 223.3
should be angularly positioned so that they are directly opposite
the previously discussed I-bolt anchors aye, 208b and 208c, in
order to provide clearance for crane hooks to engage the I-bolt
sections of the anchors. The top surface 224 of the upper section
222 of the lid 220 includes a radiation warning symbol 226, which
is preferably molded into the face of the lid 220~ An identifying
serial number may also be molded into the top surface 224 of the
lid 220 (as indicated in Figure I in order that the module 220 may
be easily identified if recovery of the module ever becomes
2 0 necessary or desirable .
As may best be seen with reference to Figure PA, three
U-shaped transporting lugs 227~, 227c and eye are placed around
the circumference of the upper section 222 of the container lid 220
approximately 120 from one another. These lugs aye, 227c and
eye are preferably offset from the flattened sections 223.1, 223. 2
and 223.3 along the circumference of the upper section 222. Such
an angular offset between these lid-transporting lugs aye, 227c
and eye and the aforementioned flat sections 223.1, ~23.2 and
223.3 minimizes the possibility that a crane hook intended for
3 o engagement with one of the I-bolt anchors of the module container
201 will inadvertently catch one of the lid transporting lugs aye,
227c or eye and accidentally tear it off. A previously
mentioned, the container lid 220 further includes an integrally
formed lower sectiosl 228 which has a slightly smaller diameter than
the disk-shaped upper section 222. A layer steel-rein~orcing mesh
229 is molded into the concrete forming the container lift 220 in the
-23--
position shown in Figure 5B. Also molded into the lid 220 ore six
equidistantly spaced cap-securing rods aye, 232b, 232c, 232d,
eye and 232f, These rods are slid into the complementary slots
aye, 214b, 214c, 214d, eye and 21~f aster the eonîainer has been
filled with nuclear waste and grouted. Both the container lid 220
and the module container are preferably molded from non-porous
portland-based concrete having 8 compressive tolerance on the
order of 4000 psi. Such concrete is both strong and resistant to
penetration by water.
Figures S and 7 illustrate a module 200 which has been filled
with high-density pucks 117 formed from the high-force compactor
110, and subsequently grouted and swapped. In operation, seven
stacks of high-density pucks 117 are centrally positioned within
the container 201 of the module 200 as shown in Figure 7. The
compacted containers which cover the compacted waste arm an
additional radiation and water barrier between the waste and the
exterior of the module 200. Next, the extendible trough 120 of
the grouting station 118 of the building 1 pours grout 21g over the
seven stacks of pucks 117 so as to form a solid layer OX g-rout
between the pucks 117 nod the inner surface of the walls of the
container 201. In the preferred embodiment, the grout used to fill
the module 200 is a 3, 000 or 4, 000 psi portland-basad concrete.
However, gypsum, poxzolan, flash or other cementitious materials
may also be used for grout. The hardened grout 218 forms a
third radiation and water barrier between the waste in the pucks
11? and the outer surface of the container 200, as is evident from
the drawing. The grout 218 also serves to anchor the
cap-securing rods aye, 232b, 232c, 232d~ eye sod 232f into the
body of the module 200, so thflt the container 201, the lid 220, the
grout 218, and the stacks of pucks 117 become a single, solid
structure having a considerable compressive and tensile strength.
The completed, hardened modules 200 arc carried from the
packaging building 1 by drop-bed trailers 184, and stacked into
the solid array 160 illustrated in Figure 3 my meals of shielded
forklifts 185.
I
Although not shown in any of the several figures, the module
200 may be specially modified to package special, high intensity
nuclear wastes such as spent control rods. Specifically, the
module 200 may be formed with very thick concrete walls so that a
relatively small cylindrical hollow space is left in the center of the
module. The control rods may then be transferred directly from a
shield transportation cask 15 into the small cylindrical hollow space
in the pre-grouted module. Such a modified module may be made
longer to accommodate several complete control rods. In the
alternative, pre-grouted modules 200 of normal height may be used
if the rods are cut up into smaller lengths.
