The original procedure and equipment for handling the slugs involved an L-shaped aiming tube beneath the process tube, into which each slug would drop as it was pushed from the process tube. The slug would fall from the aiming tube into a funnel at water level that fed into a long rubber hose that led the slug into one of three water-filled concrete discharge chutes at the rear base of the pile. The slug discharged from the hose at the lower end of this sloping chute, under about 18 ft of water. An operator standing on the floor above would sort the fuel and dummy slugs into separate buckets beneath the water.
The problems with this system were many. Slugs frequently jammed in the aiming tube, in the funnel, or in the hose. If the workers at the front pushed too hard on the column of slugs, one or more slugs might be pushed out the back and miss the aiming tube completely. With luck, such a slug would fall all the way into the basin water without striking any nozzles on the way down, and not land instead on a ledge.
The revised procedure that was thoroughly tested and put into service in early 1945 was based on the simplest of all possible techniques—simply let the slugs exit the rear of the tubes and fall freely into the basin water. The only trick was ensuring that the slugs exited the process tubes somewhat beyond the nozzles, so that they would not strike the other nozzles below.
The primary piece of equipment was the tip-off discharge fixture that would be attached to each process tube that was being refueled. It ensured that the exiting slugs fell far enough out from the face of the pile to avoid the other nozzles. It also caught the lubricating oil and water that ran from the process tube, and drained it out a pipe into a trough that ran to a process sewer. Preventing the oily mix from falling into the basin water was of great importance, as the oil would not only cloud the water and make it difficult for workers to view the slugs in the basin, it would also serve as a source of radiation contamination.
When slugs were pushed out the rear of a process tube, they fell into the basin water, landed on the padded mattress plates, and then slid down the sloping discharge chutes to the fuel storage basin. A worker standing on the floor above sorted the fuel slugs from the dummy slugs.