Door securing mechanism

A mechanism for securing a door to a door frame includes a plurality of generally C-shaped clamps rotatably secured about the door's periphery, each of the clamps including a rear radial clamp leg engageable with the rear of the door frame, a forward radial clamp leg overlying the front surface of the door, and a connecting base extending between the radial legs, with inner cam surfaces on each radial leg and an outer cam surface on the forward radial leg. A plurality of wedges are slidably secured to the door front surface for radial movement between extended and retracted positions wherein the wedge respectively engages or does not engage the inner cam surface on an associated forward clamp leg to effect latching or unlatching of each clamp about the door and frame. Each wedge includes a cam block carried by an arm overlying an associated clamp and spaced radially outwardly of the wedge cam surface to engage said outer cam surface of the associated forward clamp leg to move the rear clamp leg from the door frame as the wedge is moved to its retracted position.

BACKGROUND OF THE INVENTION 
This invention relates to a door securing mechanism and, more specifically, 
to a door securing mechanism actuatable from a remote station. 
It is necessary in various applications to securely retain a door against 
its frame in such a way that forces tending to open the door do not tend 
to open or release the securing mechanism. Additionally, many applications 
require that the door securing mechanism be capable of actuation from a 
remote station. 
Typical of such an application is a door located at the boundary of a 
nuclear reactor containment pool which seals the containment pool from a 
fuel transfer tunnel leading from the containment pool to a spent fuel 
storage pool. The storage pool is usually in a building separate from the 
containment pool and may have a second door at its boundary to isolate the 
storage pool from the tunnel. 
The doors at either end of the fuel transfer tunnel provide a means of 
positively isolating the reactor containment pool from the spent fuel 
storage pool during operation of the reactor, and allow access to the 
tunnel during refueling operations. It is necessary that the integrity of 
the seals at the tunnel ends be capable of testing during reactor 
operation. 
The doors are typically located substantially below the water level of each 
of the respective pools and must be capable of remote actuation with 
minimal effort, and should require only minimal maintenance. Further, the 
doors must be secure during seismic disturbances as well as during normal 
operation. 
SUMMARY OF THE INVENTION 
According to the present invention, a door securing mechanism is provided 
which is not released by forces tending to open the door. 
Specifically, a door securing mechanism is provided which is actuated and 
deactuated by the application of forces directed radially of the door, and 
which remains tightly locked against forces acting directly against the 
door. 
Further, the door securing mechanism of the invention requires minimum 
actuation effort, is suitable for use on doors which seat upon compression 
seals, and is adaptable for in-service seal testing. 
According to the present invention, a plurality of clamps are rotatably 
mounted about the periphery of a door to capture the door to its 
associated frame when the door is in a closed position, and are movable in 
directions normal to the door by radially movable wedges to tightly retain 
the door against the frame. 
The wedges are movable in response to rotation of a center plate to which 
the wedges are linked. Rotation of the center plate is effected by remote 
actuation. 
Other objects and advantages of the invention will be apparent from the 
following detailed description with reference to the drawings and the 
appended claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, a door securing mechanism according to the 
present invention is illustrated in place upon a door associated with a 
door frame, generally designated 10 and 12, respectively, at the terminal 
point of a fuel transfer tunnel 14 of a nuclear reactor facility. The 
tunnel 14 of FIG. 2 extends through a substrate 16 and terminates at a 
nuclear reactor containment pool boundary wall 18. The tunnel 14 
terminates at its opposite end at a spent fuel storage pool boundary (not 
shown). 
The door frame 12 comprises a cylindrical support wall 20 and an annular 
seat or flange 23. The wall 20 is concentric with and of a diameter 
greater than that of the tunnel 14, and is peripherally welded or 
otherwise secured to the wall 18. The seat 23 has outer and inner 
peripheral walls 24 and 25, respectively, and flat front and rear surfaces 
26 and 28, respectively. The rear surface 28 of the seat 23 is welded to 
the support wall 20, with a plurality of gussets 29 extending between the 
surface 28 and the wall 20. The surfaces 26 and 28 are substantially 
parallel with respect to each other and with respect to the wall 18. It is 
essential that the respective welds between the wall 20, the wall 18 and 
the surface 28 provide positive sealing. 
The seat front surface 26 has three concentric annular grooves 30, 31 and 
32. The inner and outer grooves 30 and 32, respectively, each carry an 
annular elastomer compression seal 33, and are preferably dovetailed for 
retention of the seals. The central groove 31 is connected to an internal 
radial conduit 36 for in-service leak testing. 
A pair of spaced apart hinge support arms 37 are fixed to and extend 
between the door frame 12 and the wall 18. A rotatable vertical hinge 
shaft 38 is rotatably mounted by extension through apertures (not shown) 
in each hinge support arm 37. 
A pair of hinge arms 40 are fixed to and extend between the hinge shaft 38 
and a front surface 42 of the door 10. The hinge shaft 38 extends upwardly 
to a handwheel 44 located above the surface of the reactor containment 
pool. Rotation of the handwheel 44 effects rotation of the door 10 about 
the axis defined by the hinge shaft 38. The door 10 has a generally flat 
rear surface 45 with an annular peripheral portion 46 engageable with the 
compression seals 33. 
A plate 47 is rotatably secured to the center of the door front surface 42, 
as by a mounting bolt 48 and washers 50 and 52 disposed on either side of 
the plate 47. Four retention pins 54, 56, 58 and 60 extend from the door 
front surface 42 and are spaced at 90.degree. intervals about and adjacent 
to the plate 47. Each of the pins 56, 58 and 60 carries a radially 
inwardly extending tab 62 which overlies the plate 47 to hold the plate in 
the event of fracture of the mounting bolt 48 and to limit rotation of the 
plate. 
A plurality of door clamp asemblies, each generally designated 70, are 
secured to the periphery of the door front surface 42. While four clamp 
assemblies 70 are illustratively mounted at 90.degree. intervals about the 
door periphery, it is to be understood that more or less than four clamp 
assemblies 70 may be utilized. 
Each clamp assembly 70 includes two spaced apart side plates 72 upstanding 
from the door front surface 42. A pivot pin 74 extends between the plates 
72 parallel to the door front surface 42. Referring to FIGS. 4-7, elongate 
slots 75 formed in the side plates 72 receive the pin 74 for rotation of 
the clamp 76 about an axis defined by the pin 74, and for limited travel 
of the clamp 76 normal to the front surface of the door. 
Associated with each clamp 76 is a clamp wedge assembly, generally 
designated 80, including an arm 82 received by a pair of parallel radial 
links 84 and 85 and pivotally connected thereto by a pin 86. The links 84 
and 85 receive and are pivotally connected to the disc 47 by a pin 88. 
Briefly referring to FIG. 4, it can be seen that each arm 82 terminates in 
a wedge 94 having a cam surface 95. Each wedge extends between and is 
guided by the spaced plates 72. Secured to and extending radially from 
each arm 82 is an arm 96 overlying an associated clamp 76 and terminating 
in a cam block 98 spaced radially from its associated wedge 94 and at a 
greater distance from the front surface of the door. 
The construction of a representative clamp 76 is best described with 
reference to FIGS. 4-7. Each clamp 76 is generally C-shaped and includes a 
base 100 terminating at its ends in forward and rear radial clamp legs 102 
and 104. The clamp legs 102 and 104 have inner surfaces 106 and 107, and 
110, respectively. The surface 106 is inclined from a surface 108 of the 
base 100 at an oblique angle and the surface 107 is inclined from the 
surface 106 at an oblique angle. The surface 110 of clamp leg 104 has a 
seat 112 with a surface 113 inclined at an acute angle with respect to the 
base surface 108 to mate with an inclined portion 114 of the seat rear 
surface 28. 
The angle of inclination of the clamp leg surface 106 with respect to the 
door front surface 42 corresponds to the angle of inclination of the wedge 
surface 95 when the door 10 is closed and when the clamp base is parallel 
to the seat wall 24. The clamp leg 102 additionally has outer angularly 
related surfaces 116 and 117. 
Referring again to FIG. 1, a pair of spaced arms 144 are fixed to and 
extend from the plate 47 generally parallel to the door surface 42. The 
arms 144 carry a cylindrical nut 146 which receives a threaded shaft 150. 
The cylindrical nut 146 is fixed against rotation about the axis defined 
by the shaft 150, but is free to pivot within openings in the arms 144 to 
maintain its alignment with the shaft 150, as described below. 
The threaded shaft 150 is threaded into a pair of spaced nuts 152 and 154 
positioned at either side of a shaft support block 156 which is in turn 
secured to the door surface 42. The threaded shaft 150 extends into a 
smooth oversize bore in the support block 156 and the nuts 152 and 154 
locate the threaded shaft 150 axially relative to the support block 156 
while permitting limited pivotal movement of the shaft relative to the 
block to accommodate arcuate movement of arms 144. The shaft 150 
terminates at its upper end 158 in a yoke 160 adapted to receive a mating 
yoke 162 on the lower end of remote operating structure including an 
elongate shaft 164 terminating in handwheel 166 located above the surface 
of the reactor containment pool. The yoke 162 is removable from the yoke 
160 by lifting of the shaft 164. 
DESCRIPTION OF OPERATION 
The door 10 is selectively positioned in its closed position or in an open 
position by rotation of the handwheel 44 and the shaft 38. FIGS. 3 and 4 
illustrate the door 10 in its closed but fully unlatched position wherein 
the wedge assemblies 80 are fully retracted and the clamp legs 104 are 
each positioned radially outwardly of the door 10 and frame 12, and the 
clamp pivot pins 74 are at one end of the slots 75. The cam block 98 
engages the cam surface 116 of each clamp 76 to maintain each clamp 76 in 
the position of FIG. 4. This enables opening and closing of the door. 
FIG. 3 illustrates the configuration of the door securing mechanism when 
the wedge assemblies 80 and the clamp assemblies 70 are in the positions 
shown in FIG. 4. The configuration of FIG. 3 is best described with 
comparative reference to FIG. 1 in which the door is in its closed and 
fully latched position. In FIG. 3, the arms 144 and the plate 47 have been 
rotated in a clockwise direction to angularly shift the pins 88 with 
respect to each associated wedge assembly 80 whereby each set of links 84 
and 85 is shifted angularly and radially with respect to the clamp 
assemblies 70 to retract each associated wedge assembly 80, as described 
below. 
Angular shifting of the arms 144 and the plate 47 is effected by rotation 
of the threaded shaft 150, which causes the cylindrical nut 146 to travel 
upwardly along the threaded shaft 150. During rotation of the threaded 
shaft 150, the shaft pivots about support 156, as indicated by the arrow 
180, and the nut 146 and the arms 144 carried thereby travel in an arc 
centered at the bolt 48, as indicated by the arrow 182. The pins 56-60 and 
associated tabs 62, along with the pin 54, will retain the plate 47 
substantially in its position should the mounting bolt 48 shear during 
rotation, to prevent failure of the respective wedge and clamp assemblies 
80 and 70. The absence of a tab on the pin 54 allows the arms 144 to be 
rotated to the position shown in FIG. 3, wherein the arms 144 overlie the 
pin 54. Additionally, the pins 56-60 serve as stops against which the 
associated sets of links 84 and 85 abut when the configuration of FIG. 1 
is reached. 
Clockwise rotation of the plate 47 results in retraction of each arm 82 as 
a result of a pulling action of the links 84 and 85, until each wedge 
assembly 80 has reached its fully retracted position, shown in FIG. 4. As 
each wedge assembly 80 is retracted, its associated cam block 98 engages 
the associated cam surface 116 on a clamp to urge the clamp pivot pin 74 
to an end of the slots 75 and rotate the clamp to the position of FIG. 4. 
To effect latching of the clamp 76 about the door 10 and frame 12, the 
wedge assemblies 80 are moved to their fully extended or advanced 
positions shown in FIGS. 1 and 7. Extension of the wedge assemblies 80 is 
effected by counterclockwise rotation of the shaft 150 to effect 
counterclockwise rotation of the arms 144 and the plate 47 to urge the 
wedge assemblies 80 radially outwardly through the successive positions 
shown in FIGS. 5, 6 and 7 by angular and radial shifting of the sets of 
links 84 and 85. 
As the wedges 94 are extended, each engages, in succession, the cam 
surfaces 106 and 107 to urge the clamp pivot pin 74 along the slots 75 and 
rotate the clamp leg 104 inwardly, as indicated by the arrow 184 in FIG. 
5, disposing each clamp leg 104 behind the door frame flange and adjacent 
the frame surface 114. The cam surface 107 of the leg 102 is inclined so 
as to allow unobstructed extension of the wedge 94. As the outward 
extension of the wedge 94 is continued, the clamp leg 102 continues its 
travel in the direction of the arrow 186, FIG. 6, to cause the seat 112 
thereon to tightly engage the inclined frame surface 114. The inclined 
configurations of the seat 112 and the surface 114 prevents radial 
dislocation of the seat 112 from the surface 114 by forces exerted against 
the door. 
FIG. 7 shows the wedge 94 at its fullest extension. The clamp leg surface 
117 of each clamp 76 is parallel to the overlying arms 96. In the position 
of FIG. 7, the rear door surface 45 is tightly engaged with the seals 33. 
Direct door-to-frame contact is not preferred, and the dimensions of the 
links 84 and 85, the wedge 94 and the clamp 76 are chosen to effect a 
desired seal load. Since direct door-to-frame contact is not preferred, 
minor distortion of the frame during installation is compensated for by 
the compression seals 33. 
Retraction of the wedges 94 by clockwise rotation of the plate 47 retracts 
the cam blocks 98 for engagement with the cam surfaces 116 to urge each 
clamp leg 102 toward the door surface 42 and to rotate each clamp leg 104 
radially outwardly from the door 10 and frame 12 to effect unlatching. 
It is apparent that the door securing mechanism described above is readily 
accessible from a remote station and requires minimal actuation effort, 
yet provides a positive seal between two points, such as a reactor 
containment pool and a fuel transfer tunnel, which seal maintains its 
integrity over a wide range of seismic or other disturbances which may 
occur at a distance from the location of the mechanism, since only those 
disturbances acting directly on the elements of the mechanism will 
adversely affect the integrity of the seal.