I would like to model the burnup evolution of a research reactor core up to an equilibrium core state. Specifically, my goal is to simulate several fuel cycles, where after each cycle a portion of the fuel assemblies is replaced with fresh ones, while the remaining assemblies (with their isotopic compositions at the end of the previous campaign) are repositioned within the core.
Is it possible to perform such a stepwise burnup and fuel shuffling procedure in OpenMC?
If so, could you please suggest the recommended workflow or available examples for this kind of multi-cycle modeling?
Additionally, I would like to know if it is possible to simulate only a quarter-core model (1/4 symmetry) to reduce computation time while still performing depletion calculations.
Hi Umarov, I am completing a similar project on a CANDU reactor for fuel compositional changes. In order to complete a simulation of the entire fuel cycle, you’ll need multiple workflows for different stages of the reactor. For example, for CANDU it’s online refuelling, but the refuelling doesn’t occur until the reactor has been run for a certain period of time. Therefore, the first workflow just includes running a depletion sim into a criticality search, in which I use a soluble boron in the moderator for. You can also use other reactivity devices for this stage depending on your type of reactor (varying the material or even the geometry). When refuelling begins the workflow will be, depletion→refuelling→criticality search→ repeat. Depending on how quickly reactivity varies in the reactor after refuelling and your required level of fidelity, you might need small depletion cycles in between refuelling with criticality search (ie. refuelling → criticality search→depletion→criticality search→ …. →refuelling→ repeat. This process is currently being fleshed out for OpenMC, but I have gotten it to work with a little use of the python API. They are currently working on making a much more streamlined and integrated process, but honestly it’s not too hard once you have the model completed. If you need help with this, you can message me and I can privately explain to you the process I have completed and some of the issues that arose (and I had fixed). Lastly, for your other question, it is absolutely possible for you to do a quarter-core model depending on what your results are and what type of reactor you are modelling. You need a reactor that is symmetrical along those axis, and the result you are looking for should not be highly spatially significant. Ie. If you are trying to model the reactivity devices and determine the effect of one of them being fully inserted in an accident situation, you cannot do a quarter-core, since you would technically be simulating multiple being stuck. For your situation, I don’t know the type of reactor you are working on, but if you are just trying to get the fuel composition over the duration of the plants life-cycle, you should absolutely be able to do a quarter-core, and I would even recommend it.