Supporting crown
A midnight pour
4 Jun 2018
It is close to midnight in the brightly lit basement of the ITER bioshield and, tonight, the first plot of the Tokamak "crown" is to be poured. The operation is of strategic importance: the crown will support the combined mass of the Tokamak and its encasing cryostat (23,000 tonnes) while transferring the forces and stresses generated during plasma operation to the ground.
There's a special magic to night-time operation on the ITER site...
Thousands of tonnes of concrete have already been poured into the different areas of the Tokamak Complex. But every operation is unique, due to differences in pouring techniques, concrete formulations, and even prevailing weather and temperature conditions.
Like in most challenging situations—and the pouring of the supporting crown is certainly one—the correct pouring of the different geometrical shapes of the structure was rehearsed and validated on a real-size mockup before being implemented.
It took four hours to pour approximately one hundred cubic metres of high-performance concrete into the first plot, which represents one-fourth of the total crown volume.
Another plot is scheduled to be poured in about three weeks.