Neutron thermalization in nuclear graphite: A modern story of a classic moderator

Evaluation of thermal neutron scattering law of nuclear-grade isotropic graphite

“…This is based on the assertion in Ref. [5] that vacancies in graphite are larger in size than crystals and other non-vacant region (where inelastic scattering occurs) should be highly crystalline. Note that this assumption contrasts with the modelling in the ENDF/B-VIII.0 evaluation for nuclear-grade graphite.…”

“…Currently, the ENDF/B-VIII.0 nuclear data library [3] provides practically the only TSL data for nuclear-grade graphite, and JENDL-5 [4] adopts them. However, it has recently been pointed out that the TSL evaluation method for nuclear-grade graphite employed in ENDF/B-VIII.0 have several concerns [5]. Under these circumstances, we newly evaluated TSL for nuclear-grade graphite.…”

SCALE 6.3 Modeling Strategies for Reactivity, Nuclide Inventory, and Decay Heat of Non-LWRs

“…Depending on the graphite density of a certain material in comparison to the theoretical graphite density, users can now choose between graphite TSL data of 0%, 10%, and 30% porosity. However, there are concerns related to the new TSL data for 10% and 30% porosity that are being discussed within the nuclear data community (Al-Qasir et al 2021;Ramic et al 2023;Al-Qasir 2023;Nakayama, Iwamoto, and Kimura 2024;Ramic et al 2024). Comparisons of the measured phonon density of states and graphite scattering cross sections to the corresponding calculated data from ENDF/B-VIII.0 suggest inconsistencies for the graphite data at 10% and 30% porosity.…”

ICE-MAN the Integrated Computational Environment for Modeling and Analysis for Neutrons at ORNL

“…Currently, there are two main components, OCLIMAX [2][3][4][5][6][7] and QClimax [8]. OCLIMAX is principally used on VISION (BL-16B) but can also be used to analyze phonon data from ARCS [9][10][11][12], CNCS, HySPEC [13], SEQUOIA [14][15][16][17], CORELLI, triple axes spectrometers (ORNL), LET, MAPS [18], MARI [19], MERLIN [20], TOSCA [18,[21][22][23], (ISIS), DCS (NIST), AMATERAS [19] (J-PARC), NERA [24] (Dubna) etc. OCLIMAX can calculate thermal neutron scattering cross-section of solids [4,16,17,25].…”

“…OCLIMAX is principally used on VISION (BL-16B) but can also be used to analyze phonon data from ARCS [9][10][11][12], CNCS, HySPEC [13], SEQUOIA [14][15][16][17], CORELLI, triple axes spectrometers (ORNL), LET, MAPS [18], MARI [19], MERLIN [20], TOSCA [18,[21][22][23], (ISIS), DCS (NIST), AMATERAS [19] (J-PARC), NERA [24] (Dubna) etc. OCLIMAX can calculate thermal neutron scattering cross-section of solids [4,16,17,25]. QClimax, on the other hand, provides users with a flexible, straightforward environment to enable fitting to complex user-defined functions.…”