by Judy Jackson

When Fermilab held a safety stand-down in December 1998, the proceedings included an exercise in hazard analysis. Work groups chose an upcoming task and mentally walked through it, trying to spot anything that might go wrong. Then they planned how to keep bad things from happening. All over Fermilab, little groups plotted how to keep mayhem, fiasco and trouble at bay.

One group, consisting of engineers and physicists plus a FermiNews reporter, shone the hazard analysis spotlight on the task of plugging sight risers in the new Main Injector accelerator. Sight risers are cylindrical openings, lined with metal sleeves a foot or so in diameter, that punch through the earth berm and the concrete roof of an accelerator tunnel. They allow survey and alignment teams to relate fiducial marks inside the tunnel to marks at the surface. When the risers are not in use, and in particular when the accelerator is operating, the holes must be plugged with snug-fitting concrete cylinders, to provide shielding. Our group’s job was to decide what might go wrong in the process of moving two 2,600-pound concrete plugs from a stack in a service bay, loading them onto a truck, driving them up the Main Injector berm at FZero, and lowering them into the sight riser.

We thought of plenty of potential disasters: the stack might collapse, sending 2,600 pound rollers to flatten us; the plugs could fall off the truck, which could sink up to its axles in the earth berm; the crane cable could snap, dropping the plug just as someone passed by in the tunnel below. It was beginning to seem that only a miracle could keep this job from turning deadly.

Then we began to plan: We would make sure the stack was secured before moving the plugs. Use an adequate crane and experienced riggers to move them. Build a frame to hold the plugs snugly in the truck. Wait until the ground froze before driving up the berm. Secure the area below to make sure no one in the tunnel had a Chicken Little experience....

When we were done, we had a hazard analysis plan for installing the plugs. We all signed off on it. But would it work in the field? A week later, we found out—as you’ll see on the following pages.