Hi, this is a question on neutronics simulations in general (not just openMC). For context I’m doing a literature review on the technology/commercial readiness of LiPb as a breeder material. My question is how dependable are the TBR estimations of neutronics simulations, and what are the main sources of uncertainty? I’ve seen some papers claim that neutronics simulations over-estimate TBR by as much as 10%. Thanks 
I think this paper is the state of the art on estimating uncertainty in MC simulations and Ander would be my go to person on the topic
https://www.tandfonline.com/doi/full/10.1080/15361055.2021.1895667
Applying Anders approach to get uncertainty on TBR for the specific LiPb blanket design would be the way to find out in my opinion. Just to note that LiPb blackets could be used in different blanket / reactor designs which would have different levels of uncertainty due to different materials and therefore different nuclear data. Beyond the error in the nuclear data I would also expect different fusion plasma’s have different uncertainties on the definition of neutron source (energy and location).
This is great, thank you!