Procedure for transferring objects without breaking confinement

A procedure for transferring an object along an axis, from a contaminated and radioactive zone to a clean zone without breaking the confinement when the zones are separated by a slab is disclosed. The slab contains a plug and the object can be secured to the plug with the use of a stationary pre-enclosure (43) equipped with two plugs (44 and 46) and of a movable transfer enclosure (47) equipped with one plug (48). The enclosure and pre-enclosure are placed in alignment with the transfer axis.

In a nuclear plant, areas containing hazardous materials are separated by 
thick walls and slabs from areas where personnel may be present. 
The hazardous area is generally termed the active region of the plant. The 
radioactive products which may be present in this zone include 
gamma-emitters, which justify the thick containment walls, and/or alpha 
and beta emitters, considered to be contaminants. All equipment leaving an 
active region is considered contaminated and must be placed behind a thick 
wall (to protect against gamma rays) and within a sealed enclosure (to 
avoid spreading the contamination). 
When equipment in the active region must be replaced or taken out and 
transferred to a maintenance cell, or conversely, when it is desired to 
return same to its working location, full confinement must be maintained 
throughout the transfer procedure to avoid spreading the contamination. It 
is also crucial to maintain a sufficient wall thickness as a biological 
shield between said equipment and the plant personnel as the equipment is 
transferred to the maintenance or repair cell. 
This invention concerns such a procedure for transferring an "object" such 
as a piece of equipment, a machine component, a waste drum and the like 
from the active region or containment to the clean region, for 
transporting or conveying said object within the clean region and 
transferring it back from the clean region to the active region without 
ever departing from containment and biological safety requirements. 
A first feature of the invention consists in using, for the purpose of 
maintaining confinement, a two-part device including a stationary 
pre-enclosure and a movable "transfer" enclosure. 
The pre-enclosure is kept in place throughout the time required to extract 
an object, remove it to a cell and either bring back another object or 
return the same object after repair to the active region or containment. 
The invention will be described in terms of an active cell accessible 
through its top, with transfer operations carried out vertically 
(over-the-wall handling). 
However, the same procedure applies to all geometrical arrangements such as 
through-the-wall transfer or through-the-floor. 
This description will thus concern an active cell the ceiling whereof is a 
horizontal slab with a plug therein. 
The top surface of the plug is clean and must be kept clean. The inside 
face of the plug is within the active region and is considered 
contaminated and contaminating. 
The object, at least at the time of transfer, is suspended from the plug. 
The object's dimensions are assumed to be such that, on lifting the plug, 
said object can be removed through the unplugged opening.

FIG. 1 gives a sectional view of an active cell comprising a horizontal 
slab 1 and walls 2. The plug 3 separates the active region 6 from the 
clean region 7. 
The object to be transferred 4 is suspended from the plug. The transfer 
will be carried out along axis 5, which is assumed to be vertical for 
greater clarity of the description. 
FIG. 2 shows a pre-enclosure cut by a vertical plane on the transfer axis. 
The walls 10 delimit a closed box containing two plugs, both located along 
the vertical transfer axis, namely: a lower plug 11 and and upper plug 12. 
Within said pre-enclosure, a carriage 14 can be moved horizontally by means 
of a control rod 15. For greater clarity, the wheels of the carriage, as 
well as the rails on which they roll, have been omitted from the schematic 
drawing. 
The longitudinal dimension 16 of the inside of the pre-enclosure is such 
that the passage along the transfer axis is clear when the carriage is 
located in position 17. 
The carriage positions 14 and 17 will be respectively referred to as the 
left or left-hand and right or right-hand positions throughout the 
following description. Sealing means 13 steady the tightness between the 
active cell and the pre-enclosure. 
The movable enclosure is schematically illustrated in FIG. 3 and can be 
seen to consist of a cylindrical or prism-shaped box having a wall or 
walls 30 parallel to transfer axis 36. 
The top of said enclosure is closed except for an opening for a cable 32 
sealed with a bellows 34. The end of the cable is provided with a hook 33. 
The bottom of said enclosure includes a removable plug 31 and sealing means 
35 for tightness between the enclosure and the pre-enclosure. 
Having thus described the physical features of the invention, the operating 
principle may now be explained, for example in terms of removing an object 
from the cell. 
The mutual arrangement of the components described in the foregoing is 
illustrated in FIG. 4 and the transfer operation is described with 
reference to the following figures. 
Items appearing in several figures will keep the same reference. 
Basically then, the top slab 40 of the cell comprises the plug 41 and the 
"object" to be transferred 42 suspended therefrom. 
Pre-enclosure 43 is placed on the slab in alignment with the vertical 
transfer axis. 
Plug 44 and plug 46 are in place and the carriage 45 is located to the 
left. 
The enclosure 47 is placed on the pre-enclosure in alignment with the 
transfer axis. 
Plug 48 is in place. And the hook bears the reference 49. 
Attention is drawn to the fact that neither the thickness of the enclosure 
and pre-enclosure walls, nor the sealing means between the different 
components are represented in the drawings, with intent. 
FIG. 5 shows the first step in the transfer, which consists in bringing 
together the plugs in pairs. 
Bottom plug 44 of the pre-enclosure is made fast on the slab plug 41. 
Plug 48 of the enclosure is made fast on the top plug 46 of the 
pre-enclosure and this assembled pair is placed in the carriage. A device 
not covered by the claims is used to lock and unlock the two plugs by 
means of an outside control rod (also omitted from the drawing). 
The purpose of these couplings is to protect from contamination the faces 
of the plugs which will be exposed in the clean zone. 
Thereafter, the carriage 45 is pulled to the right-hand position as shown 
in FIG. 6. 
FIG. 7 shows the hook 49 hooked onto the assembly made up of plugs 41 and 
44 and the object 42. The bellows seal around the cable has been omitted 
from the drawing. 
Said assembly 41, 44, 42 is pulled up by the cable into the enclosure 47, 
as shown in FIG. 8, whereafter the carriage 45 is moved back to the 
left-hand position as in FIG. 9 and plug 46 is returned to block the 
opening at the top of the pre-enclosure as in FIG. 10. 
It is then possible to pick up enclosure 47 and take it elsewhere. 
Confinement has been maintained throughout and enclosure 47 is now closed 
by its plug 48 whose bottom face has never been contaminated since it has 
been kept in contact at all times with the equally clean top face of 
pre-enclosure plug 46. 
The said pre-enclosure effects closure of the cell thanks to the tightness 
of the contacts (the seals 13 of FIG. 2) and top plug 46, now back in its 
initial position. 
The devices used to couple the plugs in pairs and to lift the joined plugs 
are intentionally not represented and may be of any suitable known type. 
The seals used between the cell and the pre-enclosure and between the 
pre-enclosure and the enclosure may advantageously be three-way acting 
seals. 
In FIG. 11 can be seen another embodiment of the device utilized in 
carrying out the inventive procedure. 
By way of a variant, it may be envisaged to equip the movable enclosure 
with a bell or lining cap 50 sliding snugly with seals, to avoid 
contaminating the inside of the enclosure. 
Also, the lifting and lowering operations can be effected by means of a 
specialty chain with a pushing capability, such as the locking-link 
"rigid" chain made by SERAPID (France), housed in a tunnel attached to the 
enclosure. This arrangement is illustrated in FIG. 12. 
As the figure shows, a tunnel 60 mounted on the enclosure 47 comprises a 
rigid chain 61 running over two deflecting sheaves 62, 63. To simplify, 
the opposite sheaves and the guides for the rigid chain links have been 
omitted from the drawing. 
This device affords the advantage of operating with low head-room whilst 
concentrating the plug and object lifting means on the enclosure. It is 
particularly convenient for conveying the equipment 42 and unloading it in 
a maintenance cell for repair or overhaul. 
The foregoing description outlined the procedure according to the invention 
for transferring an object which can be removed vertically and upwardly. 
It has been indicated that the procedure can be carried out vertically 
downward to feed an object into a cell and it should be apparent to those 
knowledgeable in the art that the same procedure can be applied with 
slight alteration to: 
horizontal transfer with a plug located on a vertical wall, 
vertical transfer with a plug in the floor of the cell, 
and in general a transfer along any given axis. 
The present invention has been described in relation to a nuclear facility. 
However, it is just as applicable to the transfer of objects contaminated 
by chemical or bacteriological pollutants.