Each Can is located in an underground Silo. The top of these Silos is about 29 m underground. This sketch shows the secondary salt loop in green. The secondary salt is a mixture of sodium fluoride and beryllium fluoride containing no uranium or thorium. Hot secondary salt is pumped out of the the top of the Primary Heat Exchanger to a Secondary Heat Exchanger where it transfers its heat to a mixture of sodium nitrate and potassium nitrate commonly called solar salt from its use as an energy storage medium in solar plants. The solar salt, shown in purple in this figure, in turn transfers its heat to a steam loop, shown in red, creating supercritical steam, and also reheating that steam to increase the plant’s efficiency.
Table 2 shows the main parameters of the four loops.
The design incorporates four gas tight radiation barriers:
- The primary loop piping inside the Can.
- The Can.
- The Silo cavity.
- The Silo Hall.
The first three of these barriers are more than 25 m underground.