Variable mounting assembly for transducers employed in nuclear reactor vessel inspection apparatus

A positionally variable mounting assembly for transducers used to interrogate a nuclear reactor vessel is disclosed. Means are provided for clamping each transducer of an array about its flange in a central restraining block. The central restraining block is, in turn, pivotally mounted in a yoke. The yoke is movable secured to bars or rails bolted to the transducer plate and, by loosening appropriate bolts, can be moved along the ways or pivoted about one of them. Further, the restraining block can be removed from the yoke and pivotally clamped in a different orientation to upstanding brackets attached to the transducer array plate, or rotated through 90.degree. and then secured again in the yoke.

CROSS-REFERENCE TO RELATED APPLICATIONS 
This application is hereby cross-referenced to the following patent 
applications which were commonly filed herewith and which are commonly 
assigned: 
U.S. Patent Application Ser. No. 781,403, filed Mar. 25, 1977 entitled 
"Positioning Means For Circumferentially Locating Inspection Apparatus In 
A Nuclear Reactor Vessel", filed in the name of David C. Burns; 
U.S. Patent Application Ser. No. 781,381, filed Mar. 25, 1977 entitled 
"Segmented Articulating Manipulator Arm For Nuclear Reactor Vessel 
Inspection Apparatus", filed in the names of David C. Burns and Lanson Y. 
Shum; 
U.S. Patent Application Ser. No. 781,390, filed Mar. 25, 1977 entitled 
"Pulley System Including Emergency Locking Means For Nuclear Reactor 
Vessel Inspection Apparatus", filed in the name of Renato D. Reyes; 
U.S. Patent Application Ser. No. 781,401, filed Mar. 25, 1977 entitled 
"Emergency Braking System For Nuclear Reactor Vessel Inspection 
Apparatus", filed in the name of Renato D. Reys; 
U.S. Patent Application Ser. No. 781,396, filed Mar. 25, 1977 entitled 
"Emergency Disconnect Means For The Manipulator Arm Of A Nuclear Reactor 
Vessel Inspection Apparatus", filed in the names of Arthur F. Jacobs and 
Duane W. Morris; 
U.S. Patent Application Ser. No. 781,404, filed Mar. 25, 1977 entitled 
"Pressurized Cabling And Junction Boxes For Nuclear Reactor Vessel 
Inspection Apparatus", filed in the names of Charles V. Fields and Raymond 
P. Castner; and 
U.S. Patent Application Ser. No. 781,402, filed Mar. 25, 1977 entitled 
"Emergency Retraction Means For The Manipulator Arm Of A Nuclear Reactor 
Vessel Inspection Apparatus", filed in the names of Arthur F. Jacobs and 
Duane W. Morris. 
BACKGROUND OF THE INVENTION 
Nuclear reactor vessels employed in the commercial generation of electrical 
power are of two types; the pressurized water type or the boiling water 
type. In either case, the reactor vessel utilizes a generally cylindrical 
metallic container having a base and a top flange welded thereto. The main 
cylinder portion itself usually comprises a series of lesser cylinders 
welded to each other. In addition, a plurality of circumferentially spaced 
nozzles extend through the main cylinder wall and are welded thereto. 
Thus, numerous welds are necessarily used in fabricating the reactor 
vessel, in mating the top flange to the main cylindrical body and in 
securing the inlet and outlet nozzles to the reactor vessel wall. 
The reactor vessel, in use, is encased in a thick concrete containment 
area. However, the structural integrity of the reactor vessel, the 
concrete containment notwithstanding, due to the operating environment is 
of critical importance. 
The weld areas of the reactor vessel are, of course, inspected prior to its 
initial use. Such inspection is carried out with all portions of the 
vessel relatively accessible to an inspection device prior to its 
encasement in the concrete containment. However, in-service inspection of 
the reactor vessel welds is not only desirable, but is mandated under 
governmental regulations. 
Under such regulations, it is required that the vessel weld areas be 
subjected to periodic volumetric examination whereby the structural 
integrity of the vessel is monitored. Due to the nature of an in-service 
inspection, the device designed to accomplish the specific weld 
examinations must be capable of successfully operating in an underwater 
and radioactive environment under remote control while maintaining a high 
degree of control over the placement and movement of the inspection 
sensors. 
The operating constraints are further complicated by the variety of reactor 
vessel sizes to which the inspection device must be able to be 
accommodated. Furthermore, the inspection device must not only be 
compatible with the weld placements of the reactor vessels now in use, but 
must also be sufficiently versatile to adapt to inspection duty in future 
vessels. In addition, the inspection device must be arranged in its use to 
have only minimal impact with normal refueling and maintenance operations. 
The use of ultrasonic transducers to inspect metal welds is known. One such 
system is described in the periodical Materials Evaluation, July 1970, 
Volume 28, No. 7, at pages 162-167. This article describes a 
transmitter-receiver type ultrasonic inspection system for use in the 
in-service inspection of nuclear reactor vessels. The positioning 
arrangement for the transducers uses a track which is mounted on the 
interior wall of the reactor vessel. 
A method and apparatus for ultrasonic inspection of a pipe from within is 
disclosed in U.S. Pat. No. 3,584,504. In the apparatus disclosed therein, 
a transducer array is mounted on a carrier which is rotatable, by means of 
a central shaft of the apparatus, within the pipe. 
In U.S. Pat. No. 3,809,607, a nuclear reactor vessel in-service inspection 
device is detailed, which device is adapted to permit remotely controlled 
and accurate positioning of a transducer array within a reactor vessel. 
This device comprises a positioning and support assembly consisting of a 
central body portion from which a plurality of radially directed support 
arms extend. The ends of the support arms are extended to and adapted for 
being seated on a predetermined portion of the reactor vessel to define a 
positional frame of reference for the inspection device relative to the 
reactor vessel itself. Repositioning and support assemblies are provided 
and include integral adjustment means which cooperate to permit the 
simultaneous variation of the extension of the support arms thereby 
allowing the inspection device to fit reactor vessels of differing 
diameters. A central column is connected to the positioning and support 
assemblies, which central column extends along the longitudinal axis 
thereof. One or more movable inspection assemblies are connected to the 
central column and include drive and position indicating means. Three 
specific inspection subassemblies include a flange scanner, a nozzle 
scanner and a vessel scanner. Each of these scanners employ multiprobe 
transmitter-receiver ultrasonic transducers to permit more accurate 
volumetric plotting of the integrity of the welds used in fabricating the 
reactor vessel. 
Since the development of the above-identified inspection devices, the 
original inspection code has been amended to call for more reliable and 
more rigorous inspections. In addition, these prior art devices were 
unable to accurately measure or reach certain weld areas of the reactor 
vessel. Still other drawbacks in the prior art inspection devices were the 
reliability and speed of the actual inspection effort. 
One particular problem which was not entirely solved by the above-described 
prior art devices was that of mounting the transducers, particularly where 
only a single array was to be used. Any mounting assembly used for 
securing a particular transducer to a single array plate would, of 
necessity, have to be positionally variable in order to accommodate the 
many orientations required during inspection. If such were not the case, 
the array or the entire inspection device would have to be withdrawn from 
the vessel to effect changes which would obviously slow down the 
inspection effort considerably. 
SUMMARY OF THE INVENTION 
Accordingly, there is provided a highly versatile and positionally variable 
transducer mounting assembly. A restraining block and locking means 
therefore are utilized to removably and rotatably restrain a transducer 
therein. The restraining block is pivotally secured to a yoke which 
girdles it by first connecting means which are removable for use with just 
the restraining block alone. 
The yoke and restraining block are movably secured, in turn, to guide means 
by second connecting means which permit the yoke to be slid along the 
guide means or pivoted independently with respect to the guide means. The 
guide means are bolted to the transducer array plate. The second 
connecting means are further adapted to permit the yoke to be secured 
thereto in differing orientations. The guide means comprise two rails or 
bars which are secured respectively to opposite sides of the yoke by the 
second connecting means. When appropriately adjusted, the second 
connecting means permits the yoke to be moved along the bars or pivoted 
about one of the bars while being moved away from the other. Either action 
can be performed independently of the other.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings wherein identical reference numerals have 
been used in the several views to identify like elements, FIG. 1 shows an 
exploded view of a nuclear reactor vessel 10. While the vessel 10 may be 
fabricated in differing ways, the overall cylinder which results from 
welding together the several smaller cylinders 12 is used herein as an 
illustrative example for purposes of this description. The several welds, 
A-K, shown in FIG. 1 are typically those which are to be inspected 
together with the stud holes 34 and the ligament areas 35 therebetween of 
the vessel top flange 13. It will be understood by those familiar with the 
inspection code requirements for nuclear reactor vessels, that not all of 
the welds A-K or the top flange 13 are necessarily inspected at the end of 
one time period, but that any inspection apparatus therefor must be 
capable of efficiently and accurately determining the integrity of the 
vessel welds A-K and its top flange 13, at one time or in predetermined 
code specified groupings. Further, the inspection apparatus must be 
accurately positioned to accomplish vessel interrogation without harming 
the top flange 13 and, in particular, its ability to form a proper seal 
with the vessel header (not shown). 
FIG. 2 depicts an illustrative example of an inspection site. The 
inspection apparatus 14 is shown therein seated in the reactor vessel 10. 
Prior to inspection, the apparatus 14 is assembled using an erection rig 5 
partially shown. After assembly, the inspection apparatus 14 is lowered by 
the site work crane 7 into the reactor vessel pool 11 and into the vessel 
10. The work bridge 9, also partially shown in FIG. 2, can be utilized as 
necessary. 
The inspection apparatus 14 is illustrated in FIG. 3. It comprises a 
quick-disconnect lifting assembly 16, a support ring 18 having an annular 
key 19 attached thereto, three support legs 20A, 20B and 20C, a head 
support assembly 22, a main column 24, a manipulator arm 26, a transducer 
array 28 and an overall control system 30 which includes an assortment of 
motors, resolvers and cabling, and is mainly resident in a console 31. 
These main elements cooperate, in a manner to be more specifically 
described hereinafter, to permit inspection of the reactor vessel 10 in 
accordance with code requirements. 
The inspection apparatus 14 is adapted to be lowered into the reactor 
vessel 10 and is shown in two of its many possible inspection positions in 
FIGS. 9 and 10. Prior to insertion of the inspection apparatus 14, the 
reactor vessel header is removed and tapered guide studs 32, having 
chamfered heads 33, are inserted into three of the stud holes 34 which 
have been designated for that purpose. With the guide studs 32 in place, 
the inspection apparatus 14 is fully lowered into the reactor vessel 10 
and positively seated therewithin, as shall be hereinafter explained. The 
guide studs 32 are engaged by guide stud bushings 36 which are movably 
mounted to the support ring 18. Accurate circumferential positioning of 
the inspection apparatus 14 is accomplished through the employment of the 
guide studs 32 and guide bushings 36 in conjunction with a specially 
adapted support leg show 88, to be more fully described below. 
The clearance between the guide stud bushings 36 and the guide studs 32 is 
typically a maximum of only 3/8". Therefore, it is of critical importance 
that the inspection apparatus 14 be lowered into the reactor vessel 12 
with the guide studs 32 and bushings 36 in near perfect alignment with 
each other. Alternatively stated, the inspection apparatus 14, which is a 
relatively heavy piece of equipment, must be closely aligned with respect 
to the vertical and horizonal axis or the guide bushings 36 will be cocked 
with respect to the guide studs 32 causing the inspection apparatus 14 to 
hang up thereon, which might result in damage to the inspection apparatus 
14, the guide studs 32 or the reactor vessel 10. Thus, the lifting 
assembly 16 must be adjustable to accommodate the cantilevered weighting 
effect of manipulator arm 26 and/or any weight distribution disparity in 
the inspection apparatus 14 which would cause it to tilt from a level 
attitute as it is being lowered. In addition, with the inspection 
apparatus 14 in place, the lifting assembly 16 must be quickly and readily 
removable to allow use of the inspection site work bridge 9 should that be 
necessary. 
The lifting assembly 16 is shown in greater detail in FIGS. 6, 7 and 8. 
When secured to the inspection apparatus 14, it is engaged by the site 
crane 7 which connects to the "U" bolt assembly 42 coupled to its 
uppermost portion. The "U" bolt assembly 42 is shown in FIG. 3. A 
cylindrical collar 44 having a stepped, star-shaped or cloverleaf bore 46 
is bolted to the top of the head support assembly 22. The crane 7 now 
lowers the lifting assembly 16 until a spider 48 enters bore 46, as shown 
in FIG. 6. The lifting assembly is then manually rotated about 45.degree., 
so that the splines of spider 48 are positioned to engage the hidden or 
dotted line portion of bore 46 as is shown in FIG. 7. The crane 7 now 
raises the lifting assembly 16 until the spider 48 abuts the upper surface 
of the stepped portion of bore 46 at which point it is engaged by and in 
the collar 44, as is shown in FIG. 8. 
At this point in the procedure of connecting the lifting assembly 16 to the 
inspection apparatus 14, the feet 60 of the ball and socket assemblies 50 
are held about 3/16" above the leveling pads 52. The leveling pads 52, as 
shown in FIG. 3, are connected to the upper portions of the support legs 
20. A hydraulic cylinder 54 is now actuated, causing its internal piston 
56 to push against a fixed surface 58 forcing the socket feet 60 into 
tight engagement with the leveling pads 52. Three non-adjustable base 
struts 65 are utilized to enhance the structural rigidity of the lifting 
assembly 16 and are connected between the three ball and socket assemblies 
50, as is shown in FIG. 3. As connected, the base struts form a triangle, 
the center of which is coincidental with the central axis of the lifting 
assembly 16 and the main column 24. 
The inspection apparatus 14 is thereby fully secured to the lifting 
assembly 16 and is now suspended from the crane 7 for alignment procedures 
prior to being seated in the reactor vessel 10. Such alignment procedures 
are necessary due to probable repositioning of the movable guide stud 
bushings 36 from site-to-site to accommodate differing locations of the 
guide studs 32. In addition, the position and extension of manipulator arm 
26 may be different from an inspection start at one site than at another. 
Further, the vessel locating key 62, shown in FIGS. 3 and 14, may or may 
not be in use. Consequently, the net effect of these and other possible 
causes will be to present the inspection team with a different weight 
distribution at each inspection site, thereby necessitating the alignment 
procedure. Finally, even if the same weight distribution was expected, 
proper inspection technique would demand alignment verification. 
The alignment procedure is carried out by turning one or more of the 
turnbuckle struts 64 which are rotatably adjustable and fixedly connected 
between the three ball and socket assemblies 50 and the slidable sleeve 66 
of the hydraulic cylinder 54. Adjustment of the turnbuckle struts 64 has 
the effect of gimbaling the inspection apparatus 14 about the center axis 
of the triangle formed by the base struts 65 or the lower end of the 
lifting assembly 16. This enables the inspection team to plumb the main 
column 24 of the inspection apparatus 14 and verify its vertical 
alignment. In addition, each of the three ball and socket assemblies 50 
can be individually adjusted to shift the position of the end of the 
turnbuckle strut 64 connected thereto to effect adjustment of the 
inspection apparatus 14 with respect to both the vertical and horizontal 
axes. Horizontal alignment is verified by checking the level on any one of 
the three leveling pads 52. 
The lifting assembly 16 is capable of being quickly disconnected by 
reversing the order specified above. First, the hydraulic cylinder 54 is 
deactivated causing its outer sleeve 66 to move upwards lifting the socket 
feet 60 from the leveling pads 52. The crane 7 now lowers the lifting 
assembly 16 by an amount sufficient to allow the spider 48 to fall out of 
engagement with the upper portion of the bore 46 of collar 44. Spider 48 
can now be rotated and withdrawn from collar 44. After this is done, the 
entire lifting assembly can be removed by the crane 7, freeing it for 
other work, and leaving the inspection apparatus 14 seated in the reactor 
vessel 10. Alternatively, the lifting assembly 16 can be so disconnected 
after it has been used to remove the inspection apparatus 14 from the 
reactor vessel 10, leaving the inspection apparatus 14 on resting pads 
(not shown) or on the erection rig 5 preparatory to shipment. By removing 
the lifting assembly 16 with the inspection apparatus 14 still seated in 
the reactor vessel 12, the work bridge 9 can be moved across the vessel 
pool 11 allowing for the performance of other maintenance or inspection 
procedures or to assist in the vessel inspection itself. 
Referring again to FIG. 3, there is shown three support legs 20A, 20B and 
20C. Each of these is joined to the head support assembly 22 by a spacer 
68 which is of a length appropriate to the diameter of the vessel to be 
inspected. It should be noted that for differing diameter reactor vessels, 
the spacers 68 and the support ring 18 are selected and sized so that the 
guide stud bushings 36 extend radially to a point where they will be 
aligned with and then engage the guide studs 32. Very small variations in 
radial dimensions are accommodated by loosening the guide stud bushing 
clamps 70 and inserting shims of an appropriate thickness which would have 
the effect of moving the center of the guide stud bushings 36 radially 
outward of support ring 18 as desired. It should also be noted that the 
guide stud bushing clamps 70, when loosened, permit movement of the 
bushings 36 along the support ring 18 to accommodate variations in the 
placement of the guide studs 32 in the vessel top flange 13 at different 
inspection sites. 
As previously noted, the guide stud bushings 36 are movably connected to 
the support ring 18 by the bushing clamps 70. As was also previously 
noted, the support ring 18 carries an annular key 19 about its outer 
surface. A keyway 71, see FIG. 4, cut in the surface of clamp 70, which 
mates with support ring 18, accommodates key 19 and aligns the guide stud 
bushings 70 on support ring 18 with respect to the remainder of the 
inspection device 14. In addition, support legs 20A, 20B and 20C are 
connected to support ring 18 respectively by a bracket 90, see FIG. 5, 
having a keyed hole 92 therethrough. Thus, the bracket 90 engages the key 
19 and positively locates and locks the support legs 20A, 20B and 20C to 
support ring 18 which enhances the structural stability of inspection 
apparatus 14. The leveling pads 52 are bolted or welded to the upper 
segments of the support legs 20A, 20B and 20C in horizontal alignment and 
are utilized in the manner described above. 
When seated within the reactor vessel 10, the three legs 20A, 20B and 20C 
support the entire weight of the inspection apparatus 14. Stainless steel 
shoes 84 are bolted respectively to the bottom of support legs 20B and 
20C. These shoes rest either on the circumferential vessel flange 15 or on 
the core barrel flange (not shown), depending on whether the core barrel 
has been removed. A special "A" shaped shoe 88 is bolted to the end of 
support leg 20A and is adapted to accurately position inspection apparatus 
14 as it is being seated within the reactor vessel 10. With the core 
barrel remaining in the vessel 12, a plate 94 having a keyway 96 cut 
therein is bolted to shoe 88 as shown in FIGS. 12 and 13. As it is being 
seated, keyway 96 engages a head-to-vessel alignment pin, the position of 
which is known, and positively locates the inspection apparatus 14 within 
the vessel 10. As mentioned above, the clearance between the guide studs 
32 and the guide stud bushings 36 is about 3/8" and their engagement 
yields a coarse circumferential alignment. The subsequent engagement by 
keyway 96 of the head-to-vessel alignment pin yields a fine 
circumferential alignment which provides for an absolutely certain 
placement of the inspection apparatus 14 within vessel 10. With the core 
barrel removed for inspection, the plate 94 is removed from shoe 88 and a 
vessel locating key 62, as shown in FIGS. 3 and 14, is bolted to shoe 88 
in its place. The vessel locating key 62 fits into a notch 17 cut in the 
circumferential vessel flange 15, see FIG. 11, which notch is otherwise 
covered by the core barrel flange. This engagement of notch 17 by the 
vessel locating key 62 provides the same fine circumferential alignment 
means, with the core barrel removed, as was yielded by the use of plate 
94. It should be noted that plate 94 can be built up with appropriately 
configured shims to accommodate the different sized head-to-vessl 
alignment pins that may be encountered from one vessel to another. Thus, 
by choice of the shoe 88 configuration, in conjunction with the engagement 
of the guide studs 32 by the guide stud bushings 36, the exact 
circumferential location of support leg 20A, and derivatively that of 
manipulator arm 24, is known and assured. In addition, this positive 
location or seating of the inspection apparatus is accomplished without 
touching or threatening the sealing surface of the vessel top flange 13. 
Connected immediately below the head assembly 22, as shown in FIG. 3, is a 
gear box and motor assembly 72 which drives manipulator arm 26 vertically 
along the main column 24 utilizing a pulley system 75. The main column 
itself consists of several sections of flanged pipe bolted together. 
Sections may be readily removed or added to accommodate the depth of 
reactor vessel inspection requirements. Each section is individually 
encased so that water cannot enter therein. Between the flanges 85 
thereof, the sections of main column 24 carry a track 78 which is used, in 
conjunction with a sensor to be hereinafter described, to determine the 
extent of vertical travel or, alternatively stated, to fix the vertical 
position of manipulator arm 26. The main column sections also include "U" 
shaped grooves 80 which accommodate bearings carried by manipulator arm 
26. The grooves 80 and flanges 85 combine functionally to restrain the 
manipulator arm 26 from making any unwanted or undesirable rotary 
movements about the main column 24 as it travels therealong. 
The manipulator arm 26, which is more clearly shown in FIG. 15, includes a 
carriage assembly 82 which rides on the main column 24 in the "U" shaped 
grooves 80. The carriage assembly 82 and the remainder of manipulator arm 
26 would typically be fabricated from a low weight material which can 
withstand the hostile operating environment. The carriage assembly 82 is 
fitted with internally mounted and sealed ball bearings which ride in and 
are engaged by the "U" grooves 80 and facilitate vertical movements by 
manipulator arm 26 on the main column 24. When the vertical drive motor 
(not shown) in the vertical motor assembly 72 is actuated, it rotates the 
drive pulleys 74 and 77 as is shown in FIG. 16. A pulley cable 79 is 
looped about the carriage idler pulleys 76 and 81 and the head assembly 
idler pulleys 83 and 87. When the vertical motor shaft 89 is rotated 
counterclockwise, the pulley cable 79 is released respectively by both 
drive pulleys 74 and 77 from their take-up spools 91 and 93, lowering the 
manipulator arm 26 with equal force on both sides of the carriage assembly 
82. This equalization of the release force applied to both carriage idler 
pulleys 76 and 81 insures that the carriage assembly will not be cocked 
and therefore hang-up or unduly wear its bearings as it travels down the 
main column 24. Likewise, when the vertical motor drive shaft 89 is 
rotated clockwise, the upward or lifting forces applied to the carriage 
idler pulleys 76 and 81 is equalized and the carriage assembly 82, as well 
as the remaining elements of manipulator arm 26, is lifted smoothly, at 
the proper attitude, up the main column 24. The head assembly idler 
pulleys 83 and 87 serve to define the upper portion of the pulley cable 
loop. This upper portion of the cable loop is utilized to equalize any 
cable slippage or unbalance in the cable 79 which might otherwise 
unequally tend to pull up on or release idler pulleys 76 and 81. Thus, 
except for any movement to effect compensation due to an unbalance, the 
pulley cable 79 is in motion during vertical travel of the manipulator arm 
26 only between the drive pulleys 74 and 77 and the carriage idler pulleys 
76 and 81 respectively. An emergency cable clip 99 is secured to the cable 
79 between the head assembly idler pulleys 83 and 87. If the pulley cable 
79 should happen to snap, the clip 99 will become wedged between one of 
the idler pulleys 83 or 87 and its respective support bracket 95 or 97, 
thereby restraining further vertical movement of manipulator arm 26. 
An emergency braking system 100 is shown in FIGS. 17, 18 and 19. It serves 
to halt vertical movement of the manipulator arm 26 whenever its vertical 
speed of travel exceeds a predetermined velocity, typically a speed 
greater than five inches per second. A vertical velocity rate error signal 
is developed utilizing a signal generated by the Z axis resolver 102 which 
engages the vertical track 78 and thereby follows and helps to determine 
the vertical position and rate of change therein of the manipulator arm 
26. When an overspeed condition is sensed by the control system 30, an 
emergency brake signal is forwarded to three pneumatic cylinders 104 
mounted beneath the carriage assembly 82. The pneumatically operated 
piston 106 of each cylinder 104 is connected via a header 108 to a brake 
shoe 110. The brake shoe 110 is fitted with spring loaded roller bearings 
112 which ride in bearing slots 114 in the brake shoe 110 and are normally 
urged against the "U" grooves 80 of the main column 24. In the rest 
position illustrated in FIG. 17, the emergency braking system 100 is 
disabled and the bearings 112 are spring loaded against the " U" groove 80 
holding the brake shoe 110 in its rest position and avoiding unnecessary 
wear. A cross-sectional view of the brake shoe 100 and brake lining 116 is 
shown in FIG. 19. 
When the emergency brake signal is received by the pneumatic cylinders 104, 
the pistons 106 thereof are thrust upwardly at a speed significantly in 
excess of that exhibited by the manipulator arm 26, even in its overspeed 
condition. This rapid piston movement forces the wedge shaped brake shoe 
110 upwardly into contact with the brake lining 116 which is bolted to the 
bottom of the carriage assembly 82. As the brake shoe 110 fully contacts 
the positionally fixed brake lining 116, as is shown in FIG. 18, the 
roller bearings 112 are forced inwardly in slots 114 and the brake shoe 
110 becomes jammed against the "U" groove 80 halting further vertical 
movement of the manipulator arm 26. As noted above, the speed of piston 
106 is significantly greater than the overspeed limit of the manipulator 
arm 26. It is therefore fast enough, when actuated, to overtake the 
manipulator arm 26 and cause braking action to occur even when the 
overspeed condition of manipulator arm 26 results from upward movement 
thereof. Thus, the described emergency braking system 100 functions to 
halt vertical movement of manipulator arm 26 when an overspeed condition 
occurs regardless of the direction of vertical or Z axis travel at that 
time. To insure absolute downward restraint of manipulator arm 26, an 
emergency stop plate 117, as depicted in FIGS. 3 and 15, is bolted to the 
bottom section of main column 24. Plate 117 serves to halt downward 
movement of manipulator arm 26 should the emergency braking system 100 
fail to function properly. The manipulator arm 26 is thereby prevented, by 
either the emergency braking system 100 or the stop plate 117, from 
striking the bottom of the reactor vessel 10 or any portion thereof as it 
is vertically driven in the vessel 10. 
A axis motion or rotation of the manipulator arm 26 about the main column 
24 is shown in FIG. 15. As illustrated therein, actuation of the A axis 
motor 118 drives the carriage rotary gears 122 and 124 causing the entire 
manipulator arm to swing about the main column 24. The position of 
manipulator arm 26 in the A axis is verified by a signal which is 
generated by the rotary resolver 120. It should be noted with respect to 
all of the drive motors described herein, whether shown or not, that a 
resolver or position determining sensor is coupled thereto to provide a 
signal which is then employed to indicate the position of manipulator arm 
26 or any portion thereof, in or about the particular axis of movement 
associated with the motor being described. 
Y axis movement, which is also indicated in FIG. 15, is achieved by driving 
a set of telescoping arms 126 and 128, which are movable mounted within 
the carriage channels 130, toward and away from the carriage assembly 82. 
As is more clearly illustrated in the end view shown in FIG. 17, the Y 
axis motor 132 is coupled by its shaft 134 to a drive gear 136. When the Y 
axis motor 132 is actuated, it causes drive gear 136 to be rotated, 
driving a rack 138 engaged thereby, which rack is bolted to the 
telescoping arm 126. This causes arm 126 to be driven towards or away from 
the carriage assembly 82, depending on the direction of rotation of the Y 
axis motor 132. When the outer telescoping arm 126 is moved, it carries 
with it an idler gear 140 which is meshingly engaged between rack 142, 
which is attached to the inner telescoping arm 128, and rack 144 which is 
coupled to the carriage channel 130. For purposes of clarity, the 
illustration in FIG. 17 depicts only one half of the telescoping 
arrangement of the Y axis drive, but it will be understood that the Y axis 
motor 132 causes, through the action of another drive gear (not shown), 
both sets of telescoping arms 126 and 128 to be driven in a desired 
direction along the Y axis. 
Movement of the manipulator arm 26 along the Y axis is required, in 
particular, to position the transducer array 28 within any one of the 
reactor vessel nozzles 38 for inspection thereof, as is shown in FIG. 9. 
In the event of total power failure or an inability to withdraw the 
transducer array 28 from within a nozzle 38, an emergency retraction 
assembly 140 is provided. As is depicted in FIG. 21, the emergency 
retraction assembly 140 includes a retraction cable 142 arranged within 
the carriage assembly 82 and extending therefrom to be looped about an 
idler pulley 144 which is rotatably mounted within and to the telescoping 
arm 126. Cable 142 also is guided by the half-pulley 149. One end of the 
retraction cable 142 is fixedly secured to the carriage assembly 82 by a 
clamp 146. The other end of the retraction cable 142 is formed into a ring 
150 which is detachably secured to the carriage assembly 82 at an initial 
position 152 by a removable clamp 148. The ring 150 is mounted so as to be 
accessible from above. 
When an emergency retraction of the transducer array 28 becomes necessary, 
a hook (not shown) is lowered into the reactor vessel 10 to engage the 
cable ring 150. Once engaged, the ring 150 is pulled up, which action 
frees the detechable clamp 148 from the carriage assembly 82. Upward force 
is maintained, moving the cable ring 150 from its initial position 152 
towards its final position 154. As the cable ring 150 is pulled upwards 
toward its final position 154, the retraction cable 142 forces the pulley 
144 from its initial position 156 to its final position 158. Since the 
pulley 144 is secured to the outer telescoping arm 126, it forces it back 
into the carriage channel 130 as it moves towards its final position 158. 
Simultaneously, the outer telescoping arm 126 causes the inner telescoping 
arm 128 to be moved inwardly, through manual operation of the Y axis drive 
described above, thereby forcibly withdrawing the manipulator arm 26 and 
the transducer array 28 from within a vessel nozzle 38. 
B axis motion is obtained by actuating the B axis motor (not shown) which 
is mounted within the B axis drive housing 160 and connected to mounting 
bracket 178. As is more clearly illustrated in FIG. 22, the B axis drive 
housing 160 is secured in the following manner. A mounting bracket 162 is 
bolted to each of the inner telescoping arms 128. Attached to the upper 
end portion of bracket 162 is an apertured dog ear 164. Attached to the 
upper portion of the B axis drive housing 160 is a movable linkage 
assembly 166 which is actuated by a locked-over-center lever 168. The 
linkage assembly 166 terminates in a dog 170 which engages the aperture in 
dog ear 164 when lever 168 is moved to its locked position 172 and holds 
the B axis drive housing in a normal position with respect to the 
telescoping arm 128. The bottom portion of the B axis drive housing is 
movably secured by engagement with a hinge pin 174. 
As noted above, the transducer array 28 and manipulator arm 26 can be 
withdrawn from a vessel nozzle 38 in an emergency situation. However, it 
may not yet be safe to lift the inspection apparatus 14 from the vessel 10 
since the forward portion of the manipulator arm may strike the reactor 
vessel 10. Accordingly, after the manipulator arm 26 has been manually 
retracted, the hook is again lowered and engages the linkage lever 168. As 
the hook and lever 168 are pulled upwardly, the linkage assembly 166 
extracts the dog 170 from engagement with the dog ear 164, allowing the B 
axis drive housing to rotate about hinge pin 174 as is shown in phantom in 
FIG. 22. With the B axis drive housing in its final position 176, the 
entire inspection apparatus 14 can be withdrawn from the vessel 10 without 
any fear of striking the vessel walls. 
Further movement of the transducer array 28 is possible along or about five 
additional axes of movement. In addition to movement of the manipulator 
arm 26, and derivatively movement of the transducer array 28, along or 
about the A, B, Y and Z axis, movement can be effected about the C, D, E, 
F and G axes. The B axis motor shaft is connected to a mounting bracket 
178 and, when driven, rotates bracket 178 and all elements connected 
forwardly thereof about the B axis. Two additional mounting brackets 180 
and 182 are secured to the B axis motor bracket 178, as is shown in FIGS. 
3 and 15. The C axis motor housing 184 is coupled between and secured to 
the brackets 180 and 182 with the C axis motor shaft 186 extending through 
and being drivingly engaged by the brackets 180 and 182. When actuated, 
the C axis motor drives its shaft 186 and the brackets 180 and 182, as 
well as all of the manipulator elements connected forwardly thereof, about 
the shaft 186. Motion in the D axis is achieved in a similar manner. The D 
axis motor housing 188 is also coupled between and secured to the brackets 
180 and 182 with the D axis motor shaft 190 extending through and being 
drivingly engaged by the brackets 180 and 182. When the D axis motor is 
actuated to drive its shaft 190, motor shaft 190 and all of the 
manipulator arm elements connected forwardly thereof are rotated in the D 
axis. The E axis motor housing 192 is connected to the C axis motor 
housing 188 with the E axis motor shaft (not shown) being connected to 
mounting bracket 194. When actuated, the E axis motor shaft drives bracket 
194 about the E axis, as well as all of the manipulator arm elements 
connected forwardly thereof. The F axis motor housing 196 is secured by 
mounting bracket 194 and by mounting brackets 198. The shaft 200 of the F 
axis motor (not shown) extends through and drivingly engages the mounting 
bracket 198. When actuated, the F axis motor drives its shaft 200 and the 
remainder of the manipulator arm elements connected forwardly thereof 
through F axis motion. The G axis motor housing 202 is secured to the end 
of mounting bracket 198. The G axis motor shaft 204 extends outwardly of 
housing 202 and is clamped into the transducer plate collar 206 which, in 
turn, is clamped to the transducer array plate 40. When actuated, the G 
axis motor drives its shaft 204 and the transducer array plate about the G 
axis. Thus, the transducer array plate 40 and the transducer array 28 
mounted thereon, with reference to any point in the reactor vessel 10, can 
be driven in nine planes of movement or about nine axes of rotation. This 
highly mobile and segmented articulating drive train can be employed to 
accurately position the transducer array 28 at any point within the 
reactor vessel 10. 
Ordinarily, electrical connection to and from the different motors, 
resolvers and the transducer array 28 would be accomplished by means of 
components particularly suited for use in an underwater operating 
environment. To avoid the use of such special components, which are more 
expensive and require longer delivery times, it was decided to pressurize 
the electrical cabling system allowing for the use of ordinary components. 
For example, the junction box 208, shown only in FIGS. 15 and 23 for 
purposes of clarity, can be pressurized to a degree which would prevent 
water seepage therein and thusly allow the use of standard electrical 
connectors. In order to conserve on cabling, the air supply and electrical 
supply was combined in the cabling assembly 210, shown in FIG. 23. The 
illustration in FIG. 23 is merely representative of the cabling assembly 
210 and only one cable 212 and one dual cable 214 has been shown, although 
more are used. The electrical cable 212 carries a plurality of electrical 
conductors to and from the console 31 which would typically include the 
control system 30. These conductors would be utilized to energize the 
different motors and transducers and carry signals which would report on 
transducer and resolver responses, among other things. The cable 212 is 
routed to the air supply junction box 216 which is sealed at its entry 
point therewith by a seal 218 to prevent air leakage from junction box 
216. An air supply hose 220 is also routed to the air supply junction box 
216 and carries air at a pressure significantly higher than atmospheric 
thereto. The air supply hose 220 is sealingly connected by clamp 224 about 
an air receiving nozzle 222 extending from the junction box 216. 
The cable 212 can either be through-routed through the junction box 216 or 
terminated at a connector 225 provided for that purpose. In either event, 
the cable 212 is routed from junction box 216 into the larger cable or 
hose 214. Hose 214, with cable 212 disposed therein, includes a generally 
annular space 215 along its length to carry the pressurized air where 
needed. Cable 214 is clamped over nozzle 226 by clamp 228 to provide an 
air-tight fit between the air supply junction box 216 and the dual hose 
214. From junction box 216, the hose 214 is routed to the underwater 
junction box 208. It is secured thereto by water-tight seals 230 and 232 
at the points where it enters junction box 208. From the junction box 208, 
the hose 214 can be branched by internal connectors (not shown) to any one 
or more of the motors, resolvers, transducers, etc., used in the 
inspection apparatus 14. Further, since cable 214 can depart the junction 
box 208 carrying pressurized air, various motor and resolver housings can 
also be pressurized where desired. 
As previously noted, the transducer array 28 is employed as the examination 
means by which the integrity of the vessel welds 13 or any appropriate 
portion of the vessel 10 can be inspected. A typical plan view of the 
transducer array 28 disposed on the mounting plate 40 is shown in FIG. 24. 
It should be noted with respect to the individual transducers themselves, 
that they are grouped or arrayed in a manner which permits the manipulator 
arm 26 to optimally position the plate 40 so that the greatest inspection 
flexibility results. For example, the three transducers 240, 242, and 244 
can be positioned, as illustrated in FIG. 25, to direct their ultrasonic 
beams to impinge at point 246 on the vessel 10. Transducer 242 can be 
oriented to impinge perpendicularly to the vessel wall at point 246 to 
verify the water path distance or to check for vessel flaws. Transducers 
240 and 244 can be used to direct angled beams at point 246 which may be a 
weld point or material adjacent thereto. Further, transducers 240 and 244 
may be coupled to pitch-catch or merely echo their respective beams. 
The individual transducers are secured to plate 40 by a transducer mounting 
assembly, generally designated 250, shown in FIGS. 26 and 27 in its normal 
orientation. The transducer mounting assembly includes a hollow, generally 
rectangularly shaped bar 252 having a slot 254 cut longitudinally therein. 
The bar 252 is bolted to the transducer plate 40 by bolts 256 one of which 
is shown in FIG. 27. A circular bar 258 is captured at either end thereof 
by holders 260 and fastened securely therein by set screws 262. The 
holders 260 are secured to the transducer plate 40 by bolts 264, also 
shown in FIG. 27, parallel to the spaced apart from bar 252. 
A transducer 244 is held in a retaining block 266 having a circular bore 
268 therein sized to accommodate the transducer 244. The top portion of 
bore 268 is countersunk or cut away to accept and support the flange 245 
of transducer 244 in the circular shelf 270. Plates 272, which are fitted 
over and about the transducer flange 245 and secured to the top of 
retaining block 266 by bolts 274, tightly capture and retain the 
transducer 244 in the block 266. If necessary, the transducer 244 can be 
rotated in the retaining block by loosening the bolts 274. The retaining 
block 266 includes upstanding flanges 276 and 278 having circular bores 
280 and 282 cut therethrough for respectively accepting a hinge pin 284 
therein. 
The retaining block 266 is, in turn, secured to a yoke 286 which also 
includes two upstanding flanges 288 and 290, each having a circular bore 
292 and 294 cut respectively therein. The hinge pin 284 extends through 
the bores 280 and 292 to pivotally fasten one side each of the block 266 
and the yoke 286 to each other. A set screw 296, extending from the top of 
flange 276 through a bore 298 therein is used to clamp the hinge pin 284 
to the retaining block 266. The other end of hinge pin 284 remains free to 
rotate in bore 292 of flange 288. The other side of retaining block 266 is 
also pivotally secured to the yoke 286 by a hinge pin 300, which is "T" 
shaped in cross-section. The leg of hinge pin 300 extends through the 
bores 282 and 294 of flanges 278 and 290. It is secured within bore 282 
and clamped to flange 278 by a set screw 302. The head portion of hinge 
pin 300 abuts the flange 290 and is captured by a "U" shaped clamp 304 
which is bolted to flange 290. The leg portions 306 and 308 of clamp 304 
are held together by a bolt 310 which is threaded through bores 312 and 
314 cut respectively in leg portions 306 and 308. When the bolt 310 is 
tightened down, leg portions 306 and 308 are drawn tightly together about 
the head portion of hinge pin 300 preventing it from turning in clamp 304. 
When bolt 310 is loosened, however, the transducer 244 and the retaining 
block 266 can be pivoted about the hinge pins 284 and 300 A side view of a 
pivoted restraining block 266, with transducer 244 having been tilted 
forwardly, is shown in FIG. 31. An exploded isometric view of the 
transducer 244, restraining block 266 and yoke 286 coupling is illustrated 
in FIG. 33. 
As shown in FIGS. 26 and 31, two circular sleeves 320 and 322 are fit over 
and slid along the circular bar 258 prior to its being clamped into the 
holders 260. The sleeves 320 and 322 are bolted to one side of the yoke 
286 by bolts 321. An angle bracket 324 is secured to the other side of 
yoke 286 by bolts 326. The perpendicular portion of bracket 324 is bolted 
to the rectangular bar 252 by the end bolts 328. If bolts 328 are 
loosened, the yoke 286 and therefore the transducer 244 held therein can 
be moved transversely along the bars 252 and 258. 
The bolts 328 pass through a bore 325 in the perpendicular portion of 
bracket 324 as illustrated in FIGS. 27, 30 and, most clearly, 32. After 
passing through the bore 325, the bolts extend through plate 340 and the 
slot 254 into the bar 252. The legs 330 of bolts 328 are threaded through 
the barrel nuts or pivots 342 and are pierced by cotter pins 344 at their 
terminal point ot prevent their being worked out of the barrel nuts 342. A 
centered bolt 346 is threaded through the perpendicular portion of bracket 
324 and abuts the plate 340 which acts as a stop therefor. When a locknut 
348 is loosened, the bolt 346 can be tightened down, increasing the 
distance between plate 340 and the bracket 324, thereby pivoting the yoke 
286 about the circular bar 258. An example of a pivoted yoke 286 is shown 
in FIG. 30. When the bolt 346 is tightened, the barrel nuts 342 pivot in 
the slot 254 permitting the yoke 286 to move to its canted position. It 
should be noted that the end bolts 328 are not loosened to effect or aid 
in this pivoting motion of the yoke 286. A number of bolt head flanges 350 
are used to cover and retain various bolts should they loosen and work out 
of engagement. 
As the transducer array 28 is disposed about the vessel 10, particularly in 
or near one of the nozzles 38, it becomes difficult because of the curved 
vessel surfaces, to maintain one of the transducers perpendicular to the 
vessel wall and simultaneously insure proper clearances. For that reason, 
at least two transducers 370 and 372 are mounted on upstanding brackets 
374 and 376 rather than on the bars 252 and 258. An example of this 
mounting arrangement is depicted in FIGS. 28 and 29. The restraining block 
266 is removed from the yoke 286 and is bolted to the brackets 374 and 
376. It is then pivoted at an appropriate angle by loosening bolt 310 of 
the "U" clamp 304 as previously described. In this case, however, clamp 
304 is bolted to the block 266 rather than the yoke 286. 
As shown in FIG. 29, the transducer beam 380 can be directed against the 
curved vessel wall 382, generally normal thereto, and the same transducer 
can be employed to receive the echo. Thus, the perpendicular distance 
between the transducer plate 40 and the vessel wall 382 can be 
continuously monitored. Utilizing such information, the manipulator arm 26 
can be moved accordingly to prevent collisions. Thus, there has been 
described a versatile transducer mounting assembly which tightly retains a 
transducer therein, but which can be adjusted to permit translational, 
pivotal and rotary motion of the transducer relative to the mounting 
plate. 
While the invention has been shown and described herein in considerable 
detail, such disclosure is to be considered as only illustrative or 
exemplary in character and not restrictive, as within the broad scope of 
the invention, modifications of or alternatives thereto may readily 
suggest themselves to persons skilled in this art.