Torquing can be done by other methods besides using wrenches and multipliers. When I was in the Navy, I was involved with 5 reactor refueling operations with the older and smaller GE and Westinghouse 150MW reactors. In those cases the fuel is put in while the reactor cover is off and once all the fuel modules are in place the "lid" goes on. It has an omega seal welded around the circumference to prevent leaks and then the nuts are tightened on the studs. This was done by lubricating the nuts and studs threads with a graphite/alcohol solution, tightening the nut hand tight to a line on the vessel head. Finally a hydraulic stretcher was put over the studs (two 180 degrees apart) and the stud was stretched. If I remember correctly we used a stretch equal to 1,250,000 ft lbs of torque and I was always worried the whole machine would explode as we were on top of the lid watching the hydraulic pressure gauges and those studs would make all sorts of noises!
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