Method and apparatus for handling nuclear fuel elements

An improved method and apparatus for transferring nuclear fuel elements between a fluid-filled storage pool and a cask is disclosed. The cask is supported within and is restrained by a tank which is transported between terminal locations of a nuclear facility. Transfer of fuel elements between a storage pool and the cask is accomplished by coupling the tank to a port of the pool. The transporter accurately positions and restrains the tank during transfer. In a preferred embodiment, the cask tank is unweighted from the transporter during transfer and is advanced into a fluid-sealed engagement with a port surface of the pool. In an alternative arrangement, the cask tank remains supported on the transport during its transfer and lifting means mutually engaging the transporter and tank advance the tank toward the port surface for establishing a coupling between the port and the cask. The method and apparatus substantially reduce fluid contact with an exterior surface of the cask during transfer and potential nuclear contamination; they enhance the protection of the transfer apparatus against seismic disturbances; and, they accomodate casks of different sizes.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the transfer of nuclear fuel between storage 
pools and shipping casks. More particularly, the invention relates to an 
improved method and apparatus which substantially reduces the probability 
of nuclear contamination during the transfer of nuclear fuel elements 
between a fluid-filled storage pool and a shipping cask. 
2. Description of the Prior Art 
In the operation of nuclear reactors, a controlled nuclear chain reaction 
is maintained in a reactor core by fuel elements containing radioactive 
uranium. Typically, these elements comprise long, thin, tubular structures 
made of steel, clad with a zirconium alloy and within which are packed a 
number of pellets containing a radioactive uranium composition. The fuel 
elements which can be efficiently utilized for extended periods of time 
eventually fail due to reduced activity or physical integrity. The 
resulting spent fuel elements must then be removed and replaced to assure 
safe, efficient reactor operation. 
After removal from the reactor core, the spent fuel elements are generally 
transferred to a fluid-filled fuel storage pool for retention pending 
shipment to a disposal or recycling facility. Similarly, fresh fuel 
elements can be stored in fluid-filled pools after shipment to the nuclear 
reactor location but prior to their placement in the core. Spent fuel 
elements are typically shipped from one point to another in sealed, 
fluid-filled, shielded containers called casks. Transfer of the fuel 
elements from the pool to the casks, and from the casks to the pool, must 
usually be done without removing the fuel from the fluid, using 
constantly-filtered water, to assure maximum safety. However, the art has 
experienced substantial difficulty in safely and efficiently effecting 
such transfer. Water employed in the pool or gas or air surrounding the 
spent fuel will be contaminated regardless of precautions taken. Moreover, 
even if a system were designed to have essentially zero contamination in 
the environment, prudence would still dictate treating it as if it were 
contaminated to guard against possible anomalies in the system. 
Among the early prior art transfer systems were those which immersed the 
cask in the pool to allow transfer without removing the fuel from the 
water. There were many risks attendant with such transfer systems, not the 
least of which was the total wetting of the cask exterior with 
contaminated water. The contaminated wash water produced had to be 
disposed of. 
Faced with this problem of cask contamination, there have evolved a number 
of systems for effecting transfer without wholly immersing the cask. These 
systems have come to be known as dry cask systems. Unfortunately, known 
dry cask systems have exhibited various drawbacks. 
For example, U.S. Pat. No. 3,765,549 presents a system employing a pair of 
independently-actuatable, concentric bellows mounted beneath a fuel 
storage pool and circumscribing a hatch therein. According to that 
disclosure, a fuel cask is positioned directly below the hatch and the 
bellows are extended downwardly to seat against the cask and form a 
transfer channel between the pool and the cask. The channel is then 
flooded, the hatch opened, and transfer effected. The particular 
arrangement of bellows and supporting devices shown, however, render the 
system susceptible to serious losses of contaminated material in the event 
the cask to bellows sealing surfaces do not match perfectly or if the cask 
sealing surface becomes dirty or damaged in transportation. This system 
does not provide secondary means for preventing leakage and is susceptible 
to leakage in the event of moderate seismic disturbances. 
In an attempt at overcoming certain of the difficulties of the bellows 
arrangements, U.S. Pat. No. 3,910,006 discloses that a direct contact 
between a cask and the underside of a transfer pool can be employed. This 
arrangement is said to eliminate the problems associated with large 
differential pressures on the bellows and the large amounts of water that 
the bellows arrangements must employ in the transfer channel. Here again 
different casks with different fabrication tolerances have to be matched 
with sealing surfaces beneath the fuel transfer pool and leakage cannot be 
prevented if casks do not properly match the surface or if their sealing 
surfaces become dirty or damaged in transportation. This system does not 
provide a secondary means for preventing leakage and is also susceptible 
to leakage in the event of a moderate seismic disturbance. 
In U.S. Pat. No. 3,883,012 there is described yet another dry cask system. 
In particular it is disclosed that the fuel cask can be positioned within 
a tank to accommodate casks of varying dimensions and to avoid some of the 
risks that might still surround the use of systems such as that described 
in U.S. Pat. No. 3,765,549. While this disclosure suggests lateral seismic 
restraints on the cask tank, no means are identified for suitably 
positioning the cask transporter and for restraining the cask tank while 
at the loading terminal. 
The art has thus evolved fuel transfer systems culminating in a number of 
dry cask systems. There remains however, a need for a dry cask system 
which permits safe and efficient transfer of nuclear fuel elements between 
casks and fluid-filled storage pools. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved method and 
apparatus for safely and efficiently transferring nuclear fuel elements 
between storage pools and dry casks. 
It is a further and more specific object of the invention to provide an 
improved method and apparatus for effecting transfer of nuclear fuel 
elements between storage pools and dry casks supported within cask tanks 
which are transported between transfer stations and decontamination 
stations by means which also provide effective sealing between a fuel 
transfer pool and a cask tank, accurate repeat positioning of the system 
and seismic restraint during transfer operations. 
Another object of this invention is to provide a novel port hatch means for 
efficient transfer and maximum safety from seismic disturbances. 
It is another object of this invention to provide an improved dry cask 
method and apparatus for transferring nuclear fuel elements between a 
storage pool and a dry cask positioned within a cask tank wherein the cask 
tank is advanced into mating contact with an undersurface of the storage 
pool. 
Yet another object of this invention is to provide an improved dry cask 
method and apparatus for transferring nuclear fuel elements between a 
storage pool and a cask positioned within a tank wherein the tank is 
advanced into engagement with a surface of the storage pool and the 
weights of the cask, the cask tank and a column of water in the transfer 
pool is removed from a transport means and is supported by a lift means on 
a transfer corridor floor. 
The method of the invention in one aspect comprises the steps of supporting 
and restraining a nuclear fuel element transfer cask in a tank which is 
supported upon a transport means at a first terminal location; advancing 
the transport means and supported tank to a second terminal location 
adjacent a port of a nuclear fuel or transfer pool; supporting and 
restraining the tank at the second terminal location; establishing a 
fluid-sealed channel between the port and an interior of the cask; 
flooding the sealed channel; providing access between the fuel storage 
pool and the cask through the port; and, transferring fuel elements 
between the cask and the pool. 
In accordance with another feature of the method of the invention, the tank 
is advanced into engagement with a surface of a transfer pool port, and is 
restrained in contact with the surface. A preferred embodiment of the 
invention provides for unweighting the tank from the transport means. 
Yet another object of this invention is the provision of an improved method 
and apparatus for transferring nuclear fuel elements between a storage 
pool and dry cask supported within a cask tank, wherein paired bellows 
arrangements have nuclear shielding material positioned therebetween. 
It is yet another object of this invention to provide an improved method 
and apparatus for transferring nuclear fuel elements between storage pools 
and dry casks supported within cask tanks wherein novel bellows 
arrangements are efficiently engaged in sealing contact. 
An apparatus in accordance with the invention for transferring nuclear fuel 
elements between a fluid-filled storage pool and a fuel element cask, 
including a tank transport means for supporting and advancing a cask tank 
between a first terminal location and a second terminal location adjacent 
a port in a fuel transfer pool. A cask tank means is provided for 
supporting and restraining the cask within the tank during transport and 
transfer and for protecting the cask from contamination during the 
transfer. A port closure means operable between a closed position for 
sealing the port in the pool, and an open position for enabling the 
passage of fuel elements between the fuel transfer pool and the cask 
interior is also provided along with a means for coupling the tank to the 
fuel transfer pool and for restraining the tank. 
In a preferred embodiment of the apparatus of the invention, a means is 
provided for unweighting the cask tank from the transport means at the 
second location and for advancing a surface of the tank into engagement 
with a transfer pool port surface and for restraining the tank in 
engagement with the surface. An alternative embodiment of the apparatus 
provides means for supporting the cask tank on the transport means and for 
advancing the cask tank into engagement with the port surface. Other 
features of the apparatus provide for restraining and accurately 
positioning the transport means and means integral with the transport 
means for restraining the tank. 
In still other alternative embodiments of the invention, the cask tank is 
supported on the transport means at the second location and extensible 
coupling means are provided for coupling between the tank and the port. 
Other features of the apparatus provide for restraining and accurately 
positioning the transport means and means integral with the transport 
means for restraining the tank.

DETAILED DESCRIPTION 
The method and apparatus of this invention enables spent fuel to be removed 
from a spent fuel storage pool and to be loaded into a spent fuel shipping 
cask for removal from a nuclear plant. It will be appreciated that the 
method and apparatus of the invention can also be employed for 
transferring fuel from the cask to the pool. Moreover, the type of 
facility, whether it be a nuclear power plant, a nuclear fuel processing 
plant or other facility requiring transfer of fuel elements, is not of 
importance to this invention which has utility wherever cask pool transfer 
systems are required. Accordingly, the following description, referring to 
transfer of spent fuel from a pool to a cask, must be taken as 
illustrative and not limiting of the invention. 
Referring now to FIGS. 1 & 2, one embodiment of the apparatus of the 
invention is shown in position to effect transfer of fuel elements. The 
apparatus comprises a cask 5, a cask tank transport means 1, a cask tank 
means 2, cask tank lifting and support means 3, a port closure means 4. 
Controls for sequentially actuating the various devices and mechanisms 
disclosed herein can be freely adapted from known techniques depending 
upon the particular timing and sequencing desired. The cask tank means 2 
is supported and guided on the cask tank transport means 1, when not 
connected to fuel transfer pool 9, and houses the fuel cask 5. In 
operation for fuel element removal, an empty cask 5 is positioned in the 
cask tank means 2 at a first decontamination terminal location 6. The 
transport means 1 advances the tank means to a second terminal location 13 
beneath a pool port 7 at an opposite end of a transfer corridor 14. The 
lifting and supporting means 3 then lifts the tank 2 to port 7 and 
supports it at this position as shown on FIGS. 1 & 2, and cask tank 2 is 
sealed to port 7 near its top portion. At this location, an interspace 54 
between the interior of cask 5 and the port 7 below a port closure cover 8 
is flooded. The cover 8 is then raised as shown in FIG. 1 to permit 
transfer of fuel elements from a fuel transfer pool 9 to the cask 5. 
FIG. 1, which is a fragmentary view of a building 10 of a nuclear fuel 
handling facility, illustrates a fuel storage pool 11, the transfer pool 
9, and a transfer canal 12. The transport means 1 and tank means 2 are 
shown positioned at the second terminal location 13 which is a fuel 
element loading terminal of the facility. The cask tank 2 is supported by 
lifting means 3 and sealed to port 7 near the top part of cask tank 2. The 
port closure means 4 is shown in both closed and opened positions. The dry 
cask handling apparatus is thus shown conditioned for a fuel element 
transfer operation. 
Fuel racks 15 are located within the fuel storage pool 11 vertically 
supporting fuel assemblies (not shown) submerged in a fluid, as for 
example water, which fills the pool. Adjacent to the fuel storage pool 11 
is the fuel transfer pool 9 connected thereto by the fuel transfer canal 
12 having provision for the installation and removal of canal gates (not 
shown) to permit the movement of fuel assemblies between the storage and 
transfer pools by means of a fuel handling machine (not shown), typically 
a crane. Within the fuel transfer pool 9 can be a cask head storage ledge 
16. At the bottom of the transfer pool 9 is the port 7 which communicates 
with the transfer corridor 14 below. The cask tank means 2 is shown 
laterally restrained by the transport means 1 directly below the port 7 
and vertically supported by lift means 3. 
The transport means 1 of FIGS. 1, 2, and 3 includes means for accurately 
positioning the cask tank beneath the port and for providing horizontal 
and vertical transport restraint. The transport means 1 is shown locked to 
the walls of the building 10 at the terminal location 13 on transport rails 
17 on which it travels. Transport side guide shoes 18 (FIGS. 2 & 3) are 
shown bearing against transport side guide rails 19 which, as shown partly 
broken away for clarity, are fixed to the building walls on opposite sides 
of the corridor 14. This arrangement accurately positions the cask tank 
beneath the port 7 and restrains the lateral movement of the transport 
means 1. Transport lock bars 20 are provided and have tapered entrance 
ends which enable them to enter sockets 21 even when slightly out of 
alignment and force the transport means into accurate alignment with port 
7. Lock bars 20 are shown extended in their locking position in which they 
engage lock bar sockets 21 formed in opposite walls at the first and second 
terminal locations 6 and 13 respectively. In FIG. 1, a socket 21 is 
illustrated on the distant wall of the terminal location 6. The lock bars 
20, when extended into the lock bar sockets 21 on both sides of corridor 
14, not only accurately position the transport means at each of the 
terminals 6 and 13, but they also restrain horizontal movement in a 
direction parallel to rails 17. 
The cask tank means 2 is lifted to an elevated position as shown in FIG. 2, 
by lift means 3. The cask tank top flange 24 is then engaged with and 
sealed to an embedment seal ring 62. 
A means is provided for guiding vertical movement of the cask tank means 2 
through the transport frame 26 and comprises a plurality of guide rails 84 
mounted to the outside of the cask tank 2 which engage guide shoes 85 (FIG. 
3) mounted to the transport frame 26. After the transport means is 
accurately positioned at the terminal location 13 as was described 
hereinbefore, the cask tank 2 is raised by the lifting means 3. The guide 
rails 84 and guide shoes 85 maintain accurate positioning of the cask tank 
2 as it is raised and assure that the tank top flange 24 engages the 
embedment seal ring 62 to establish a seal. Alternative to the guide rails 
and shoes, a cylindrical guide body, such as body 284, shown on FIG. 8, 
mounted to or used with cask tank 2 can be used to guide vertical movement 
of the tank. When the cask tank top flange is disengaged at the loading 
terminal 13, and at all other positions, from embedment seal ring 62, the 
cask tank means 2 is lowered to the transport 1 and is supported by its 
flange 56 in contact with the transport frame 26. 
A feature of the dry cask handling apparatus embodiment of FIG. 2 is the 
unweighting of the cask tank means 2 from the transport means 1. When the 
cask tank means 2 is coupled to the embedment seal ring 62, all of the 
vertical load is supported by lift means 3 at terminal location 13. The 
height of water in fuel transfer pool 9 is supported by cask tank means 2 
in addition to the weight of the internally positioned cask 5. In the 
embodiment of FIG. 2, this entire loading is transferred directly to the 
floor slab through the lift means 3. As a result, the transport means 1 is 
structurally designed to support and transport only the weight of cask 5 
and cask tank means 2 but not the weight of the column of water at 
terminal location 13. The transport means can accordingly be made lighter 
in weight and therefore is less costly. Because of the support by the lift 
means 3, the apparatus of the embodiment of FIG. 2 is substantially rigid; 
its natural frequency is high, and the seismic loads which are related to 
natural frequency of the system are therefore low. At terminal 13 the 
transporter supports the cask tank means 2 against lateral loads through 
the guide rails 84 and the guide shoes 85. These lateral loads are 
transferred to the building walls through transport side guide shoes 18, 
transport side guide rails 19 in a first direction, and through transport 
lock bars 20 in a second direction. Cask tank top flange 24 and lift means 
3 can be used, in addition to transport 1 to support lateral loads if so 
desired. Lift means 3 supports all vertical loads when the port cover 8 is 
open and cask tank means 2 is subjected to high loads from the head of 
water in fuel transfer pool 9. 
Lift means 3, shown in FIGS. 1-2, 12-13 comprises a lift base structure 63 
having a support 502, a lifting head 64, support block 506 mounted as by 
welding to the head 64 for vertical movement therewith, hydraulic lift 
cylinders 66, a lift lock block 65 supported on a slide plate 504, a plate 
actuating piston 508 and actuating cylinder 67, a hydraulic power unit (not 
shown) and controls (not shown). FIG. 12 illustrates the lift in a 
retracted position. During a lifting sequence, the lifting head 64 is 
raised by hydraulic cylinders 66 mounted on lift base structure 63. The 
lifting head 64 is horizontally guided and restrained by guide shoes (not 
shown) also mounted on lift base structure 63. When the lifting head 64 is 
raised to its high position, the guide plate 504 and the lift lock block 65 
supported thereon are advanced under block 506 of the lifting head 64 by 
the lift lock actuating cylinder 67. Following this, the support block of 
lifting head 64 is lowered on to the lift lock block 65. All of the 
vertical loads applied to cask tank means 2 are then supported on blocks 
65,506, and support 502. No cask tank means 2 vertical loads are then 
carried by the transport means 1 or by hydraulic cylinders 66 during fuel 
element transfer. 
The lowering sequence of lifting head 64 starts with initially raising the 
lifting head 64, a short distance to unload block 65 as shown by the 
dashed lines in FIG. 13 withdrawing the guide plate 504 and lift lock 
block 65 by actuating cylinder 67 and then lowering the lifting head 64 by 
hydraulic cylinders 66 until cask tank mean 2 is lowered to the transport 
means 1 and is supported by its flange 56 in contact with the transport 
frame 26. The lifting head 64 is further lowered to provide adequate 
clearance from cask tank means 2. 
Alternatively, the lifting means comprises an arrangement (not shown) 
having a single hydraulic piston-cylinder which is centrally located under 
the cask tank subsystem 2. When a hydraulic piston-cylinder assembly is 
provided for accomplishing vertical movement of the cask tank 2, means are 
provided for mechanically locking the piston in a raised position to 
inhibit lowering of the cask tank subsystem, in the event that hydraulic 
pressure is interrupted during fuel transfer. 
As a further alternative, mechanical lifting jacks for providing the 
necessary vertical upward force and movement can comprise a plurality of 
conventional, self-locking, screw jacks which are driven simultaneously by 
a common motor (not shown) through suitable shafting and gear boxes. 
When the cask tank means 2 of FIGS. 1 and 2 is lowered by lift means 3 from 
an elevated position, it decouples from port 7 and engagement with 
embedment seal 62 is interrupted. The tank 2 which is positioned in an 
aperture 87 (FIG. 3) of the transporter frame 26 is guided during descent 
by the plurality of guide rails 84 extending from an outer surface 25 of 
the tank and by the guide shoes 85 which are mounted to the transporter 
frame. As shown in FIG. 2, the tank 2 is provided with an annular support 
flange 56 and a plurality of structural ribs 57. The flange and ribs are 
mounted to an outer surfaces 25 of the tank. The annular support flange 56 
engages and supports the tank on the transporter frame 26. 
The transporter means includes transport wheels 23 and 23' which support 
the transport frame 26 and engage and travel on rails 17. These rails are 
mounted to wall ledges 37 of the building 10. Wheels 23' are traction 
wheels and are driven by a motor and gearing 27 (FIG. 3) which is fitted 
with a spring applied magnetically-released, or equivalent brake. A 
driving force is transmitted to the wheels by drive shafts 28. The 
traction wheel drive is similar to the drive of a conventional overhead 
crane bridge or trolley except that provision is made in the electrical 
control to magnetically release the brake while the motor is de-energized 
and the locking bars 20 are being driven into their respective socket 21. 
A suitable control is provided to assure that the brake on the motor 27 is 
released when the locking bars 20 are engaging the sockets 21. Each locking 
bar is actuated by a suitable mechanism 29 such as a jack screw or 
hydraulic or pneumatic cylinder, which mechanism also provides means for 
guiding and supporting the locking bar throughout its movement. 
Restraint of the transport means 1 is provided against horizontal movement 
in a direction perpendicular to the side guide rails 19 as previously 
described, and also against vertical upward movement by means of 
horizontal guide shoe surfaces 30 which bear against the bottom of the 
side guide rails 19. Buffers 31 on both ends of the transport frame 26 are 
shown and adapted to engage buffer plates 32 which are mounted at end walls 
of corridor 14 at each terminal. The buffers 31 are provided to dissipate 
the energy of the moving transport means and its supported loads and 
thereby absorb the shock of inadvertant overtravel at either terminal 6 or 
13. The buffers are alternatively hydraulic or mechanical and, in the case 
of overtravel, strike buffer plates 32 which are fixed to the end walls of 
corridor 14 at both terminals. 
In the embodiment of FIG. 2, the cask 5 is supported within the cask tank 
means 2 by a cask support adaptor 90. Cask supporter adaptor 90 is 
described in detail hereinafter with respect to FIGS. 5, 6 and 7. Cask 
supporter adaptor 90 can be used when a relatively quick internal change 
of the cask tank means 2 is required, as, for example, to receive a cask 5 
of relatively larger or smaller dimension. Alternatively, other means 
comprising separate cask bottom support structure and separate upper guide 
plates can be utilized. 
FIG. 4 is an enlarged view illustrating in detail one embodiment of the 
cask top sealing details used with the embodiments of the dry cask 
handling apparatus of FIGS. 1, 2, and 8. The embedment seal ring 62 is 
annular and is shown mounted by welding below ceiling 22 of corridor 14 to 
plate members of port embedment 88. A pair of annular inflatable seals 72 
and 89 for sealing the cask tank means 2 to the bottom of port 7 are 
mounted to embedment seal ring 62 and engage tank top flange 24 thus 
providing a waterproof seal between the tank and port 7. Mounting of seals 
72 and 89 to horizontal and vertical faces respectively of the seal ring is 
provided by suitable adhesives such as an epoxy resin or by other 
mechanical engaging means. The seals 72 and 89 are separately actuated, in 
a preferred embodiment, by air pressure after the cask tank means 2 has 
completed its engaging vertical movement and the cask tank top flange 24 
is engaged to embedment seal ring 62. 
Cask tank top flange 24 is mounted near a periphery of a top segment of the 
cask tank means 2. When it is advanced vertically upward it closely engages 
the embedment seal ring 62. Cask tank top flange 24 also restrains movement 
of the upper segment of the cask tank means. The cask tank top flange 24 
comprises an annular shaped angle body having a vertically extending 
surface 81 and an integral, transversely extending surface 82 which with 
seals 72 and 89, seal and establish a fluid sealing engagement. 
An annular gutter 49 extends about the periphery of the top flange segment 
of the cask tank means 2. A wall 45 of the gutter 49 is of double wall 
construction having plate wall members 46 and 47 and an annular core of 
radiation shielding material 58 positioned between the wall members. 
The gutter 49 also provides a low point from which water in the interspace 
54 and in the port 7 below the port closed over (FIG. 12) can be drained 
after the fuel transfer operation is completed and the port cover 8 is 
closed and sealed to the floor of the transfer pool 9. 
The inside wall 51 of the annular gutter 49 serves to provide mounting 
space for a guided adaptor ring 50 which is slideably mounted in contact 
with the inner circular wall 51 of the gutter 49 to permit vertical 
movement of an adaptor plate 52 to accommodate slight variations in the 
heights of similar fuel casks 5. The guided adaptor ring 50 is sealed to 
the bottom of the annular gutter 49 by means of a flexible bellows 53 
which enables vertical movement of the adaptor plate 52 while sealing the 
space between cask and tank against leakage. 
The adaptor plate 52 is positioned on top of guided adaptor ring 50 and 
seals are provided in order to prevent the entry of water into an annular 
space between the outside of fuel cask 5 and the inside of cask tank means 
2. The adaptor plate 52 is shown sealed to the guided adaptor ring 50 by 
means of annular seals 75. It is similarly sealed to a surface of a 
segment of the top of cask 5 by seals 76. A clamping force between the 
adaptor plate 52 and the guided adaptor ring 50 is provided by a plurality 
of swing bolts 77 fastened to the guided adaptor ring 50. A separate 
adaptor plate 52 is required for different types of casks to accommodate 
differing end constructions. 
In FIGS. 1 and 2 a novel port closure means 4 of this invention is shown in 
detail. The port closure means 4 provides an effective fluid seal in a 
closed position, is readily disengaged to an open position, and is 
restrained in the open position. In FIGS. 1 and 2, the cover 8 is shown in 
dotted lines in an open position, and in solid lines in a closed position. 
Referring to FIG. 1, the port closure means 4 which forms a fluid and leak 
proof seal between fuel transfer pool 9 and the corridor 14 is shown in its 
open position with port cover 8 tensioned against backstop beams 33. The 
port closure means 4 includes the port cover 8 mounted to a pivot arm 34 
which rotates about a pivot bearing and support fixed to the transfer pool 
floor, the lifting cables 35, port cover actuator 36, and port cover base 
37 which is recessed in the transfer pool floor about port opening 7. In 
FIG. 2, concentric protective rings 38 and 38' are shown which serve to 
protect a sealing surface 39 of the port cover base 37 from impact by 
objects which could distort the seal surface and disable sealing 
engagement with port cover base 37. The inner protective ring 38 is a 
circular ring proportioned to absorb the energy of a heavy falling object 
and is positioned with respect to port cover base sealing surface 39 at a 
location which enables the seals to engage a bottom surface of the closed 
port cover 8. The outer protective ring 38' is similarly located outwardly 
with respect to port cover sealing surface 39 for enabling engagement with 
the bottom seals of the cover 8 and above an optional vertical inflatable 
seal (not shown) which seals against the vertical outside cylindrical 
surface of the closed port cover 8. Protective rings 38 and 38' are 
provided with passages for draining pool water into interspace 54. 
Backstop beams 33, as shown in the fuel transfer pool 9, are mounted to 
and supported by the sidewalls of the transfer pool. They provide a 
restraint against which the port cover 8 is held and seismically 
restrained in an open position by the tensioned cable 35. 
A circular header pipe 68 is positioned in the port 7. The header pipe 
includes a plurality of spray apertures or orifices (not shown) arrayed 
for directing an effluent thereof into interspace 54. The purpose of the 
header pipe is to spray wash water into the interspace 54 on an underside 
of the cover 8 and all other internal surfaces which may become 
contaminated with radioactive particulates during the transfer of fuel 
assemblies through the port 7 and interspace 54. 
FIGS. 5, 6, and 7 illustrate a cask support adaptor 90, previously shown in 
FIG. 2. FIG. 5 is a vertical cross-section view of cask support adaptor 90. 
FIG. 6 is a cross-section taken at line 6--6. FIG. 7 is a cross-section 
taken at line 7--7. This cask support adaptor comprises a cylindrical 
shell 91 having a plurality of lower and upper guide shoes 98 and 98' 
respectively, which engage internal, elongated, vertical extending ribs 40 
of cask tank means 2 and guide and restrain the cask adaptor 90 within cask 
tank. The cask adaptor includes a vertical support bottom ring 96 which 
engages a cask tank base ring 44 positioned on cask tank base 43. Beveled 
surfaces between the vertical surfaces of adaptor bottom ring 96 and cask 
tank base ring 44 are provided to accurately position the bottom of cask 
support adaptor 90 in the cask tank means 2 and to support the cask 
support adaptor base against lateral loads. The adaptor bottom ring 96 is 
connected to cylindrical shell 91 by the means of an adaptor base 
structure 95 and adaptor base plate 92. The cask is vertically supported 
within cask support adaptor 90 by cask support ring 93, which is part of 
adaptor base plate 92. Additional horizontal support for the bottom of a 
cask (not shown) positioned within the adaptor is provided by lateral 
radially extending supports 94 which are adjustable in a radial direction 
and are fastened to adaptor base plate 92. For clarity in FIG. 5, the fuel 
cask 5 is not shown but is shown in FIGS. 6 and 7. 
FIG. 5 also illustrates upper, elongated guide plates 97 at opposite 
chordal positions located at the top of cask support adaptor 90. These 
guide plates position the top of the fuel cask 5 and restrain horizontal 
movement of the top of the fuel cask 5 in all horizontal directions. Upper 
guide plates 97 are provided with converging entry surfaces to facilitate 
entry of fuel cask trunnions 48 when a fuel cask 5 is introduced into the 
adaptor by lowering into the adaptor 90. 
A separate cask support adaptor 90 is required for each size and 
construction of fuel cask 5. The outer dimensions, guide shoes 98 and 98', 
and adaptor bottom ring 96 are substantially the same for all cask support 
adaptors. The height of adaptor base structure 95 will vary in accordance 
with the height of a particular cask. The adaptor base plate 92, cask 
support ring 93, supports 94 and upper guide plates 97 are selected to 
accommodate the weight, geometry and other physical requirements of a 
particular cask. Apertures and cutouts in cylindrical shell 91 and base 
plate 92 serve to reduce the weight of the cask support adaptor 90 and to 
enable any collected liquids to drain directly into the cask tank means 2. 
The function of a one piece cask support adaptor 90 is to provide quick 
conversion capability for a dry cask handling apparatus wherein a variety 
of sizes of fuel casks are are to be handled within a short period of 
time. Such would be the case in a spent fuel storage or reprocessing 
facility where different sizes of casks are shipped from different nuclear 
power generating stations. When quick conversion capability for 
accommodating different types of spent fuel casks is not needed, as would 
be the case in nuclear generating stations wherein a single size of cask 
may be used for fuel element removal over a long period of time, a 
separate cask bottom support and structure, comprising bottom ring 96, 
structure 95, base plate 92, cask support ring 93, and radial supports 94 
can be used in conjunction with separate upper guide plates 97 without the 
use of the cylindrical shell 91 and without the guide shoes 98 and 98'. In 
this case, both separate supports can be bolted to cask tank ribs 40, to 
cask tank base structure 43, and to cask tank base ring 44. 
FIG. 8 illustrates an alternative embodiment of the dry cask handling 
system of this invention. According to FIG. 8, the cask tank means is 
supported by the transport means and is restrained against movement in all 
horizontal directions, but is free to be raised on the transport or lowered 
onto it. In FIG. 8, members are numbered between 201 and 300. As with the 
description of FIGS. 1, 2, 3 and 4, all members performing functions 
similar to those previously described bear the same last two digits. The 
cask tank means 202 is supported on the transport means 201 and is raised 
and lowered by a force applied to a flange 256. This is accomplished in 
one embodiment by use of a cylindrical body 284 to which a cask tank 
mounting flange 256 is mounted. The body 284 is raised by a plurality of 
hydraulic or mechanical jacks 266 spaced and supported on the top of the 
transport frame 226. Body 266 is guided during vertical movement by a 
plurality of guide shoes 285 about the body. A plurality of lock pins 265 
are shown extending into apertures in the body 284 when the cask tank 
means 202 is at a fully elevated position at the loading terminal 213. In 
this raised position, the cask tank top flange 224 engages the embedment 
seal ring 262 and the seal between them is effected. This ceiling coupling 
is shown in greater detail in FIG. 4, which was described hereinbefore. 
The cask tank means 202 includes means positioned within the cask tank for 
supporting and restraining casks of varying dimensions. In FIG. 8, the 
cask tank means 202 is shown to include a plurality of elongated internal 
ribs 240 which are provided with spaced holes 241. The spaced holes 
provide for incremental vertical adjustment of the cask base 295 which 
supports the fuel cask 205. 
Cask supports 294 are fastened to the base to support the lower end of cask 
205 laterally and/or vertically. A plurality of connecting shoes 298 are 
spaced around the periphery of the cask base 295 and are each provided 
with a plurality of holes 241' to match the holes 241 in the vertical ribs 
240 to provide incremental vertical adjustment of the cask base 295 within 
the cask tank to permit utilization of fuel casks of different heights. 
While the particular embodiment shown employs vertically spaced holes, it 
will be apparent to those skilled in the art that any suitable means for 
cooperatively engaging the ribs and the connecting shoes can be employed. 
Inside the upper end of the cask tank means 202 are also shown adjustable 
supports 297 for laterally supporting the upper end or trunnions 248 for 
the fuel cask 205 from the vertical ribs 240. The vertical ribs 240, in 
combination with the cask support base 295, the upper support means 297 
and the means for engaging them provide effective lateral restraint of the 
cask 205 within the cask tank means 202. 
FIG. 9 illustrates yet another embodiment of the dry cask handling 
apparatus of this invention. According to FIG. 9, the cask tank 302 is 
fastened to transport means 301 and is restrained against movement in 
vertical and horizontal directions by the transport means. In FIG. 9, 
members are numbered between 301 and 400. As with the description of FIGS. 
1, 2, 3, 4, and 8, all members performing functions similar to those 
described bear the same last two digits. The cask tank means 302 is bolted 
to transport means 301 and is connected to the transfer pool 309 by 
coupling means 303. 
An embodiment of the coupling means 303 shown in FIG. 9 comprises an 
extensible sealing means. The extensible sealing means includes a lower 
connecting flange 369 integral with a movable shielding ring 359, which 
can be raised or lowered to provide clearance for advancing the cask tank 
means 302 horizontally during its transport. 
A bottom surface of the lower flange is provided with seals, described in 
more detail hereinafter with respect to FIG. 10 for fluid sealing flange 
369 to the cask tank top flange 324. 
An extensible means is mounted on a top surface of the lower connecting 
flange 369. This extensible means comprises concentric, annular flexible 
bellows 370 and 371 which are mounted and sealed at upper ends thereof to 
a port bottom plate 361 location in the ceiling 322 of the corridor 314. 
Flexible bellows 370 provides a primary, inner seal against leakage of 
water from the interspace 354. Flexible bellows 371 provides a secondary 
outer seal for redundance. In addition it, in combination with flange 369, 
plate 361 and bellows 370 and 371 provides an annular air tight chamber 373 
in the space between the bellows 370 and 371. The lower connecting flange 
369 is raised and lowered by the application of vacuum or air pressure, 
respectively, to the chamber 373. 
Radiation shielding is provided with the coupling means 303. Within the 
annular chamber 373 is a stationary nuclear radiation shielding ring 360 
which is mounted to and suspended from port plate 361. This shielding ring 
overlaps the movable radiation shielding ring 359 and, with radiation 
shielding ring 358 on the cask tank 302 forms a continuous radiation 
shield above the top of fuel cask 305. 
Within the annular chamber 373 is also positioned a cylindrical plate 374 
supported from plate 361 and located in close proximity to the inner 
bellows 370. The purpose of cylindrical plate 374 is to prevent the 
bellows from expanding excessively in a radial direction in the event of 
an inner bellows failure. A similar cylindrical plate 378 is shown in 
close proximity to the outside of outer bellows 371 for a similar purpose 
and in addition to protect the outer bellows 371 from damage by contact by 
external objects. 
Positioned radially inside the bellows 370 and forming a vertical extension 
of the port 307 is a cylindrically shaped protective barrier 379 having a 
conically shaped distal segment 379'. The barrier 379 protects the bellows 
370 from impact by and resulting damage from objects passing through the 
interspace 354. 
A circular header pipe 368 is positioned in the port 307. The header pipe 
includes a plurality of spray apertures or orifices (not shown) arrayed 
for directing an effluent thereof into port 307. The purpose of the header 
pipe is to spray wash water into the interspace 354, on the underside of 
the cover 308 and all other internal surfaces which may become 
contaminated with radioactive particulates during the transfer of fuel 
assemblies through the port 307 and interspace 354. A similar circular 
header pipe 368' is positioned in an annular space between the inner 
bellows 370 and the protective barrier 379 for washing surfaces which are 
not reached and washed by a spray of header pipe 368. 
During vertical movement of the extensible coupling means 303 the flange 
369 is guided by a plurality of guide shoes 380 which are mounted to the 
flange and engage a plurality of guide rails 383. The guide rails 383 are 
affixed to and suspended from ceiling 322. This guiding means, comprising 
guide shoes 380 and guide rails 383 accurately positions the flange 369 
and restrains it against horizontal movement. This guiding means also 
includes upper and lower stops, (not shown), for limiting vertical travel 
of the flange 369. 
FIG. 10 illustrates in greater detail the embodiment of the coupling means 
303 described above. In FIG. 10, annular compression seals 372 are shown 
positioned on a flange plate 369' on the flange 369 of cask tank 302. The 
flange plate 369' is maintained in contact with the flange 324 and the 
seals are compressed and rendered functional by the weight of movable 
members of the coupling means 303. A sealing force exerted between the 
flange plate 369' and flange 324 can be supplemented by introducing 
compressed air into the annular chamber 373. During engagement, the 
sealing force is maintained and is supplemented by a plurality of latch 
bolts 399. These bolts maintain the flange 324 and flange plate 369' in 
engagement in the event of seismic or other forces tending to separate 
them. 
The adaptor plate 352 is shown sealed to the guided adaptor ring 350 by 
means of annular seals 375. It is similarly sealed to a surface of a 
segment of the top of cask 305 by seals 376. A clamping force between the 
adaptor plate 352 and the guided adaptor ring 350 is provided by a 
plurality of swing bolts 377 fastened to the guided adaptor ring 350. 
Disengagement of the flange 369 and the flange 324 is effected by releasing 
air pressure and applying a vacuum to the annular chamber 373. A means (not 
shown) is provided for securing the flange 369 at an elevated position, 
when the coupling means 303 is disengaged from the tank means 302. 
Referring now to FIG. 11, there is shown another embodiment of the coupling 
means 303 according to the present invention. Whereas in FIGS. 9 and 10, 
the extensible coupling means 303 was mounted to the ceiling 322 and was 
extensible to engage flange 324 of the tank 302 the arrangement of FIG. 11 
provides for mounting the coupling means to a tank 402 and it is extensible 
therefrom to engage a plate 462 secured to the ceiling 422. 
In FIG. 11, the members of the coupling means 403 are numbered between 400 
and 500. Those members which perform functions similar to functions 
performed by members previously described, bear the same last two digits. 
Bellows 470 and 471 are shown mounted to a horizontal flange plate 424 on 
cask tank 402 and move with the cask tank means 402 during transport. A 
flange 469' is shown in engagement with a sealing flange plate 462 which 
is mounted to the port embedment plate 461 and is provided with seals 472. 
The connecting flange 469 is raised and its compression against sealing 
flange plate 462 to effect a fluid seal is accomplished by introducing 
compressed air into the annular chamber 473 between bellows 470 and 471. 
Lowering of the flange 469 to disengage the coupling means 403 is effected 
by venting the annular chamber 473 to atmosphere and allowing the upper 
connecting flange 469 to lower by gravity. During engagement the coupling 
force established by air pressure is supplemented by a plurality of latch 
bolts 499. These bolts maintain flange plate 469' in engagement with 
sealing flange plate 462 in the event of loss of air pressure in chamber 
473 or the occurrence of seismic forces tending to separate them. 
An improved method and apparatus for the handling of nuclear fuel elements 
has thus been described. The method and apparatus are advantageous in 
reducing the possibility of contamination of a cask surface by fluid 
flowing from a nuclear fuel storage pool. The apparatus is further 
advantageous in that it provides substantial restraint of a fuel element 
cask with respect to seismic forces. Other features and advantages 
described hereinbefore include adaptable tank means for receiving and 
restraining fuel casks of various sizes. The cost of the apparatus for 
handling fuel casks of different sizes is thereby reduced. By unweighting 
a cask tank from its transport means and supporting and seismically 
restraining the tank in a vertical direction from a floor bed of a 
building structure, the forces normally imposed upon the transport means, 
not only in supporting the tank and its enclosed cask, but also the loads 
established by a hydraulic head of a storage pool, enables the transport 
means to be substantially lighter, less complex, less costly and more 
reliable. The transport means advantageously includes means for 
establishing lateral seismic restraints on the tank and in an alternative 
embodiment supports the tank during fuel transfer. In one particular 
embodiment, the tank is elevated from the transport means into engagement 
with a port plate and in another particular embodiment, an extensible 
means is provided for coupling between the tank and the port. Overall, the 
method and apparatus provide for enhanced safety of operation as well as 
reduced complexity and cost. 
While there have been described particular embodiments of the invention, it 
will be appreciated by those skilled in the art that variations may be made 
thereto without departing from the spirit of the invention and the scope of 
the appended claims.