Binding in the Lazy Susan of the 1 MW TRIGA at the Centro Nuclear de Mexico

Problems with the original Lazy Susan were reported in a previous conference, where the procedure followed for its removal was described. A new Lazy Susan was supplied by the fabricant and it was judged convenient to perform an out-of-core test of the dispositive. A rig was built to produce temperature gradients similar to the ones encountered in the operation at high power levels. After a temperature difference (estimated between 130oC and 170oC) between the rotating part and the outside surface was established, the Lazy Susan started to bind. This was reported to the fabricant and it was concluded that a new design was needed and since it would take at least two years before the new unit could be acquired, it was decided to install the Lazy Susan recently supplied. The unit now rotates for approximately 20 minutes when the reactor is operating at 1 MW and then binds. At lower power levels it is operative for longer periods of time. (author)