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The Silo

Silo Hall Cross-section
Silo and Silo Hall

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:

  1. The primary loop piping inside the Can.
  2. The Can.
  3. The Silo cavity.
  4. The Silo Hall.

The first three of these barriers are more than 25 m underground.

Table 2
The Four Loops (flows are per module, fuelsalt is fresh)

Mass Flow Hot Hot Cold Cold Fluid
kg/s C bar C Bar numbers are mol fraction
Fuelsalt 2994 704 10.5 564 4.0 NaF-BeF2-ThF4-UF4 76/12/9.8/2.2
Secondary Salt 1534 621 10.5 454 20.0 NaF-BeF2 57/43
Tertiary Salt 1414 598 12.0 344 1.0 NaNO3-KNO3 55/45
Steam Main 225 538 248 288 260
Steam Reheat 162 538 38 343 39

NEXT: Fuelsalt Drain Tank