Cyclic flows prevent depletion

[LukeSeifert]

If a flow regime is defined which has a complete cycle, even if the flows are set to move no mass, then no depletion will occur. Because this does not cause an error in Serpent, it is more difficult to figure out exactly what is going wrong. Found in v2.31.

• For example, imagine a geometry that has 3 materials in it named 1, 2, and 3, respectively. If the flow regime is defined such that 1 → 2 -> 3 → 1 or 1 → 2 → 3 → 2, then the flow is cyclic in nature and will not allow depletion to occur.

• Find a workaround
• Determine issue in Serpent
• Find a workaround in Serpent
• Fix in Serpent