Hello All,
I want to know what the lowest value of OpenMC’s output can reach. In a recent flux simuation, I found that the flux is displayed as 0 far away from the source, and the value can only reach 10E-6. I want to know if there is a way to show a smaller value.
Thanks.
Welcome to the forum @Occulter. Once you get to regions of very low flux, you’re really limited by the number of events occurring and how much they score to a tally, not by the precision of the numbers that OpenMC is using internally (double precision, meaning we could in principle store a value down to 1e-308). The lowest value will be given by whatever score is accumulated when you have a single event that scores to a tally. If you want to see how many events are scoring to a tally on average (for each source particle), you can tally the ‘events’ score.
To add to this, if you’re doing deep shielding problems like this, you’ll need some form of variance reduction to get the particles to the low flux region you’re interested in efficiently. There is some ongoing work to add weight windows to OpenMC, which should better enable calculations like this.