US2978790A

US2978790A - Apparatus for handling nuclear reactor fuel elements

Info

Publication number: US2978790A
Application number: US675201A
Authority: US
Inventors: Challender Ronald Scott; Knights Herbert Chilvers
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1956-08-22
Filing date: 1957-07-30
Publication date: 1961-04-11
Anticipated expiration: 1978-04-11
Also published as: NL106521C; FR1181175A; DE1042777B; BE560240A; CH355227A; NL220092A

Description

April 11, 1961 R. s. CHALLENDER ET AL 2,978,790

APPARATUS FOR HANDLING NUCLEAR REACTOR FUEL ELEMENTS Filed July so, 1957 3 Sheets-Sheet 1 April 11, 1961 R. s. CHALLENDER ET AL 2,978,790

APPARATUS FOR HANDLING NUCLEAR REACTOR FUEL ELEMENTS Filed July 30, 1957 3 Sheets-Sheet 2 April 11, 1961 R. s. CHALLENDER ETAL 2,978,790

APPARATUS FOR HANDLING NUCLEAR REACTOR FUEL ELEMENTS Filed July 50, 1957 5 Sheets-Sheet 3 United States Patent f APPARATUS FOR HANDLING NUCLEAR REACTOR FUEL ELEMENTS Ronald Scott 'Challender, Appleton, near Warrington,

and Herbert Chilvers Knights, Meebrow, Risley, England, assignors to United Kingdom Atomic Energy Authority, London, England Filed July 30, 1957, Ser. No. 675,201 Claims priority, application Great Britain Aug. 22, 1956 7 Claims. (Cl. 29-33) V This invention relates to apparatus for handling nuclear reactor fuel elements comprising a fuel member enclosed by a protective sheath. It is an object of the invention to provide apparatus for removing the sheath from such fuel elements by physical means.

Apparatus according to the invention comprises an annular die with a leading cutting edge, a support in front of the die to support a fuel element approximately coaxial with the die, locating means to locate with the fuel element to bring it truly coaxial with the die, means for advancing the fuel element relative to the die so as to pass the fuel member part of the element through the die whilst cutting away the sheath and means for applying a bow-restraining force to the fuel element during the initial cut of the die.

An embodiment of the invention will now be described with reference to the accompanying drawings wherein:

Fig. 1 is a plan view partly in section; the chain-dotted outline shows the right hand cross-head in the position it occupies at the end of the stroke;

Fig. 2 is a section on the line II-II of Fig. l; and

Fig. 3 is a section on the line IIIIII of Fig. 1.

An annular die with a leading cutting edge 11 is carried in a block 12 fixed by screws 13 and X-shapcd cross head 14 secured to the twin box-girder frame 15 (Fig. 2) of the apparatus by flanges 16. The cross head 14 has two bushes 17 associated with one leg of the X and two supports 18 associated with the other leg of the X: the bushes 17 carry sliding thrust rods 19 and the supports 18 carry fixed guide rods 20.

In front of the die 10 there is a fuel element support cradle which comprises two V-shaped carriers 21 carried on arms 22 linked together by a plate 23 and channelsection bar 24. The arms 22 pivot on a pin 25 carried by a part 26 of a box-girder of the frame 15 of the apparatus. One arm 22 has an extension piece 63 over which moves a push-rod 64 movable in a journal 65 secured to the box-girder 26. The push-rod 64 has a step 66 which abuts the journal to limit the downward movement of the rod. The upward movement of the rod 64 and corresponding retracted position of the arm 22 etc., is shown by the dotted lines 67. A transversely-finned fuel element 28, resting in the V-carriers 21 is approximately coaxial with the die. The fuel element 28 is made truly coaxial by conical location with a nose support 29, movable in the die 10 and carried in a cross-head 36, and a tail support 30 carried in an X-shaped cross-head 31. The nose support 29 has a conical indentation '32 to mate with the conical end cap 33 of the fuel element 28. The tail support 30 has a conical pointed end 34 to mate with the end cap 35.

The crossheads 31 and 36 are associated with one another by the thrust-rods 19 which have shouldered ends 37,38 where they bear against the cross-heads. In the case of end 37, nuts 39 fix the crosshead 36 firmly against the shoulder. In the case of end 38 the crosshead 36 has a degree of free movement between the shoulder and nuts 40. The cross-heads are movable on the 2,978,790 Patented Apr. 1 1 1961 guide rods 20 and are provided with bushes 41, 42. for this purpose. Crosshead 31 is coupled with a hydraulic ram 43 by bolts 44.

Between the two cross-heads 36, 31 and around the tail support 30 there is a minor cross-head 45 slidable on busbar 46 on the guide rods 19 and on busbar 47 on the thrust rods 20. The minor cross-head 45 is also slidable about the tail support 30. A spacing rod 48 is screwed into the cross head 45 and it has a head 49 which contacts a lug 50, which is one of two lugs supporting the guide rods 20 at the ram end of the apparatus.

The cross-head 36 carries the nose support 29 in a central boss 51 and the support 29 is spring loaded by a compression spring 52 and has an advancing slot 53. The support 29 is retained in the boss 51 by a retaining plate 54. Twoimpact heads 55 extend from the crosshead 36.

The ends of the rods 20 are secured by nuts 56, 57:

the nuts 56 tightened against the lugs 50 and the nuts 57 tightened against bridges 58 in an impact block 59.

The block 59 has a centre projection 60, two end projections 61 and end ledges 62 in which a fuel member can be located prior to being struck by the impact heads 55 and broken into pieces of suitable size and shape for feeding to an extraction plant dissolver. 'The chaindotted outline of the cross-head 36 in Figure 1 illustrates that the fuel member is broken into four pieces by the action of the impact heads 55 in conjunction with the center projection 60.

Diametn'cally opposite one another, are two retractable anti-bowing struts 68 hydraulically operated by rams 69 and fitted with rollers 70. The retractable struts 68 are conventional. They slide in guides 91 and are operated by rams 69 driven from cylinders 92. The concave rollers 70 fitted to the ends of the struts 68 are shaped so as to grip a fuel element in the machine when the struts 68 are advanced and they rotate about their vertical axis to allow the fuel element to be pushed past them by the ram 43.

In Fig. 3 the ram is shown at the end of its stroke after release of the stripped fuel element 28 by means of a trip mechanism 71 whichcomprises a lever 72 pivoted on a pin 73 secured to the crosshead 36 and a cam 74 fixed to one of the bridges 58. The lever 72 has a ball end 75 which is located in the slot 53 in the head 77 of the nose support 29.

In operation, the cross head 31 is drawn back against.

element 28 to be stripped is placed in the V-carriers 21 e (which have been raised to the position shown in the drawing by depression of the rod 64) and the crosshead 31 carrying the tail support 30 is advanced to take up the fuel element 28 between the support 30 and the nose support 29 so as to be coaxial with the die. The spring 52 compensates for any slight variations in fuel element length. The carriers 21 are retracted and the anti-bowing struts 68 are advanced so that the rollers 70 crush the fins and hold the fuel element 28. The movement of the struts 68 is limited by stops so that the fuel element, at least at the point of contact with the rollers 70, is brought into a straight line with

supports

29 and 30. The ram 43 is further advanced to bring the fuel element end cap 33 into the die 11. The die cuts through the cap 33 (a heavy cut in which bowing of the fuel element would occur if not restrained by the struts 68), the struts 68 are retracted and the ram 43 pushes the rest of the fuel element 28. through the die 11 (a light operation not creating bowing tendencies).

The sheath is peeled off and the fuel member part of the fuel element remains held by the

supports

29 and 30 and the cut inner parts of the caps 33 and 34. When the lever 72 of the mechanism 71 strikes the cam 74 the ball end 75 is advaneed ahead of the cross-head 36 together with the support 29 so that the fuel member is released and the cut inner parts of the caps 33, 34 fall off. The ram 43 proceeds and the impact heads 55 strike the fuel member in the block 59 to break it into four approximately equal pieces. The ram 43 is now drawn back and the relative friction of the sliding parts is such that the draw back to the positions shown in Fig. 1 is reached. Once the cross-head 36 abuts the cross-head 14, the ram draws back the cross-heads 31 and 45 towards the nuts 46. The head 49 of the pin 48 then strikes the lug 50 so that the cross-head 31 continues its journey alone to the nuts 40 and draws the support 30 through the cross-head 45 in so doing thus making sure that any parts of the fuel element adhering to the support 30 are detached. The fuel member which has been stripped of its sheath and released is picked up with tongs and placed in the block 59 in readiness for the next cycle and the pieces of the broken fuel member are fed to an extraction plant.

The operation is carried out under water so that the operators are shielded from dangerous radiations but able to see What they are doing. The principal parts of the apparatus are therefore constructed of material which is not corroded by the water. Rubbing parts are chromium plated carbon steel; other parts are mild steel, aluminium sprayed.

We claim:

1. Apparatus for separating a tubular casing from a body enclosed therewithin, comprising an annular die having an inside diameter no greater than the diameter of the body and a cutting edge at one end thereof, first means slidably mounted within and co-axial with the annular die for positioning the body, means mounted opposite the cutting edge of the die and to reciprocate relative to the die for moving the body relative to the die, and second means mounted on the reciprocating means co-axial with the first means and for positioning the body, whereby the reciprocating means forces the body through the die as it is suspended between the first and second positioning means to separate the casing therefrom.

2. Apparatus according to claim 1 wherein the reciprocating means is a ram assembly mounted to reciprocate in a path co-planar with the axis of the die, and the first and second positioning means are cylindrical members adapted to slide within the annular die, the first being normally mounted within the die and the second being normally fixed in the ram assembly to lie co-axial with the first, the cylindrical members having opposing ends adapted to support the body.

3. Apparatus according to claim 1 further comprising retractable means mounted transverse to the axis of the die between the cutting edge and the reciprocating means and including rollers disposed adjacent the axis of the die for engaging the tubular casing and preventing bowing therein.

4. Apparatus according to claim 1 further comprising retractable means mounted transverse to the axis of the die between the cutting edge and the reciprocating means and including a carrier element disposed adjacent to and extending parallel tothe axis of the die for aligning the body between the first and second positioning means-for engagement therewith.

5. Apparatus according to claim 4 wherein the carrier element is a V-shaped member, the vertex thereof being disposed parallel to the axis of the die.

6. Apparatus according to claim 1 further comprising resilient means mounted on the reciprocating means and urging the first positioning means toward the second positioning means, means mounted on the reciprocating means and engaging the first positioning means for overcoming the bias of the resilient means, and means mounted in the path of the reciprocating means and disposed to engage and actuate the means for overcoming the bias of the resilient means, whereby the body is released from engagement with the first and second positioning means.

7 7, Apparatus according to claim 6 wherein the reciprocating'means is a ram assembly mounted to reciprocate in a path co-planar with the axis of the die, the ram assembly including a member with a recess disposed opposite the other end of the die from the cutting edge, the resilient means being disposed in the recess, the first positioning means being a cylindrical member normally mounted within the annular die and having oneend engaged with the resilient means in the recess, the means for overcoming the bias of the resilient means being a lever pivoted on the ram assembly member and engaging the cylindrical member, and the means for actuating the means for overcoming the bias of the resilient means being an element mounted in the path of the ram assembly and being disposed to engage the lever to release the body by advancing the cylindrical member ahead of the ram assembly.

No references cited.