2021/01/22 by J. Romero-Barrientos, Romero-Barrientos, Jaime
Engineering · Materials Science · Physics and Astronomy · #Computational Physics (physics.comp-ph) #FOS: Physical sciences #Graphite, nuclear technology, radiation studies #Nuclear Materials and Properties #Nuclear Physics and Applications #Nuclear reactor physics and engineering
paper · pdf · doi:10.48550/arxiv.2101.09338
openalex publication_date 2021/01/22 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
In the field of nuclear reactor physics, transient phenomena are usually\nstudied using deterministic or hybrids methods. These methods require many\napproximations, such as: geometry, time and energy discretizations, material\nhomogenization and assumption of diffusion conditions, among others. In this\ncontext, Monte Carlo simulations are specially adequate to study these\nproblems. Challenges presented when using Monte Carlo simulations in space-time\nkinetics in fissile systems are the different time-scales involved in prompt\nand delayed neutron emission, which implies that results obtained have a large\nvariance associated if an analog Monte Carlo simulation is utilized.\nFurthermore, in both deterministic and Monte Carlo simulations delayed neutron\nprecursors are grouped in a 6- or 8- group structure, but nowadays there is\nnot a solid reason to keep this aggregation. In this work, and for the first\ntime, individual precursor data is implemented in a Monte Carlo simulation,\nexplicitly including the time dependence related to the \β-delayed neutron\nemission. This was accomplished by modifying the open source Monte Carlo code\nOpenMC. In the modified code -- Time Dependent OpenMC or OpenMC(TD) -- time\ndependency related to delayed neutron emission originated from \β-decay\nwas addressed. Continuous energy neutron cross-sections data used comes from\nJEFF-3.1.1 library. Individual precursor data was taken from\nJEFF-3.1.1 (cumulative yields) and ENDF-B/VIII.0 (delayed neutron\nemission probabilities and delayed neutron energy spectra). OpenMC(TD) was\ntested in: i) a monoenergetic system; ii) an energy dependent unmoderated\nsystem where the precursors were taken individually or in a group structure;\nand finally iii) a light-water moderated energy dependent system, using\n6-groups, 50 and 40 individual precursors.\n