Fast power reactor simulation employing a GPU-based continuous-energy Monte Carlo method

The computational barrier imposed on the continuous-energy Monte Carlo (MC) power reactor calculation was overcome by exploiting state-of-the-art GPU computing techniques. PRAGMA is a GPU-based continuous-energy MC code tailored to commercial PWR analysis, and it can exploit gaming GPUs to retain practicality. The unionized grid method is improved for GPUs by introducing a linear hashing scheme, and the random neutrons are cast into GPUs by an event-based tracking algorithm. Fuel partitioning and energy sort schemes render significant performance for depleted fuel analysis. Dedicated calculation schemes for power reactors such as multilevel spectral collapse (MSC) for depletion, localized delta-tracking (LDT), domain decomposition, and fission source convergence acceleration with CMFD and ramp-up enable efficient large-scale power reactor simulations employing massive particles. The performance of PRAGMA using a single gaming GPU was equivalent to that of a conventional MC code using 500 cores of a flagship CPU, and the full-scale BEAVRS cycle 1 depletion calculation using 360 billion histories was completed in 16 hours employing 24 gaming GPUs