I have a degree in Nuclear engineering, although I haven’t been practicing in a while. Your explanation is accurate and well described. > actually I think ther

I have a degree in Nuclear engineering, although I haven’t been practicing in a while. Your explanation is accurate and well described. > actually I think there are two sets of rods, not all of them are individually actuated commercial reactors have 5-10 “banks” arranged symmetrically, although only a subset of those are typically used during power operations [1], so you weren’t far off. Rods are rarely controlled individually, the only case that comes to mind is for identifying and then limiting the reactivity in a “leaker” fuel bundle (one where the cladding has been breached by a foreign object, so it is leaching contamination into the coolant - this is undesirable but expected). [1]: edit for more information: PWRs and BWRs differ substantially here: PWRs primarily use boric acid in the coolant to limit reactivity at the beginning of a fuel cycle, which is diluted out over the course of the cycle. One bank of rods is used for fine reactivity control. This gives them a generally even power distribution across the reactor. BWRs primarily use their control rods, so start the fuel cycle with substantially more inserted. A significant part of designing the fuel layout for a cycle is also designing the control rod patterns to be used over the cycle, to control excess reactivity while maximizing fuel use. Power distribution across the reactor can vary wildly, so it’s a much more challenging engineering problem. I just remembered I actually have a detailed visualization illustrating (modeled) power distribution in a BWR. You can easily see where control rods are inserted and how that has shifted the power around. https://www.kmr.me/posts/coremap/#content https://www.kmr.me/posts/coremap/#content