SPENT FUEL ROD PROCESSING (WIRE REMOVAL)


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Integrated Double Shear (Generation 1)
Features:

The Integrated Double Shear uses the same shearing device that is currently being used to free the wire from the fuel rod. The difference is, besides several new components, is that it shears both ends with this shearing device.

The operator loads the Canister, which drops fuel rods into the Integrated Double Shear, as needed.

The Clappers position the wire on the "spade end" of the fuel rod so that it can be cut.

The Shackles, near the top of the Integrated Double Shear, straighten the rod so it can be inserted into the upper shear. We know that many of the fuel rods get bent when they are removed from the core assembly.

After the bottom is cut, the upper shear will slide down the uprights onto the top of the rod or the lower shear will rise to lift the fuel rod into the upper shear.

When the top end of the fuel rod is inserted into the upper shear, the One-Tooth Gear positions the wire for cutting.
Integrated Pacman (Generation 1)
Features:

The Integrated PacMan uses a new shearing concept. The PacMan can described as a pair of scissors with a hole at the center of pivot (of the two shears). The hole is just big enough for the fuel rod to fit in, so when the shear blades come together, the wire is sheared (see picture).

The T-Bar, which is loaded by the operator, dispenses fuel rods into the PacMan shear as needed.

The Shackle Arm is used to straighten out the fuel rod and make sure that it is completely inserted into the PacMan shear.

The One-Tooth Gear positions the wire so that it is cut when the PacMan "jaws" begin to close.

The Pacman shear shears the wire. The rod is ejected and the wire pieces fall onto the Slotted Pan. The Slotted Pan separates the fuel rod from the wire pieces and delivers each to a storage container.


Integrated Double Shear (Generation 2)
The second generation of the Integrated Double Shear uses the same general concept as the first generation, in that it uses two of INL's original shearing devices

Changes:

1. The second generation has eight shackles (four on each side) to account for bent rods. The shackles fire from bottom to top to straighten/postition the top of the fuel rod. The shackles will be driven by electric or argon pneumatic actuators. Bent rods shown in assembly are from empirical data collected by the INL.

2. A motor will lower and lift the top shear by means of cable/pulley, rack/gear, or screw.  Shown is the cable/pulley option.

3. More Detail has been given to the "one tooth gear" concept.  and Clappers.

Problems:

1. Loading the Integrated Double Shear is performed by operator.

2. Sorting of wire from fuel rod is performed by operator. Both will be ejected into a basket and then later sorted - the fuel rods to the casette (for chopping) and the wires to the wire chopper.

To Be Explored:

1. Integrate canister/hopper into system.

2. Modify bottom shear to allow for horizontal translation. After process, the top part of the bottom shear will slide to one side and drop the fuel rod and wire into a basket. This would save labor for the operator and solve part of problem #2, listed above.

Operation Time

Estimated Cost (for prototype)
Integrated Pacman (Generation 2)
The second generation Pacman design uses many of the same concepts as before, with exception to the following changes.

Changes:

1. New fuel rod delivery system that takes the rods from the canister to the pacman shear.

2. Linkage systems have been added to the pacman shear to allow us to use linear solenoids rather than rotational.

Problems:

1. The overall assembly is large (about 55-60 inches long). Setting the assembly on a tilt, as well as downsizing components, are possible solutions to this problem.

2. The fuel rod delivery system is not quite complete in drawings, but will rely on one linear solenoid as well as one rotational solenoid.

3.  Orientation of fuel rods relies on a socket that would be complex to build.
Proof of Concept Prototype
The Proof of Concept Design took the automated Pacman concept and made it manually operated. We did this because of time constraints and because the Pacman must be proven as a functional device before the time is put into electronics for automation, etc.

Features:
 
The Clamp acts as a loading device and a clamping device. The operator places the rod onto the clamp, then the clamp swings towards the shears and inserts the rod into the shears. The clamp then presses the fuel rod into the shears to make sure it doesnt "pop" out.

The Tabs guide the fuel rod into the shears and also mount the clamp to the overall assembly.

The Shears rotate around the fuel rod and cut the wire.

Testing:

In testing, we found that the end shears will cut the wire, but the middle shears will not cut because of deflection in the Top Bar. Also, the clamp needs to have "fingers" pressing down on the plenum end and the spade to keep the rod from bowing.

It is very easy for the fuel rod to not be inserted completely into the shears (which results in the shears damaging the cladding). This is something that needs to be improved.

Solutions:

There are two solutions that we think will make the Pacman completely functional. First, the Top Bar and Bracket Bar can be thickened and reinforced to reduce deflection. Second, the shears can be redesigned so that all don't cut at the same time. This would reduce the overall load in the system and thus reduce the deflection in Top Bar.

Images
Complete Pacman Prototype