Simulated homogenized two-group cross sections of advanced nuclear reactor designs for noise analysis

A set of 2-group cross sections, group velocities, and delayed neutron fraction and decay constants are generated from full 3-D geometry and continuous energy model of advanced nuclear reactor systems. The purpose of the data is to perform quantitative investigations with 2-group 1-D reactor noise models. The homogenized and collapsed 2-group cross sections are generated with the Serpent2 continuous energy Monte Carlo code.

The simulations model the active core and reflector regions of the reactors both radially and axially, and in some cases even the surrounding of the reactors such as the shielding and the pressure vessel is included. The reactor cores are always considered to be at fresh, hot conditions. The region of interest for the group constant homogenization is set to the active core.

The following reactor concepts are included in the dataset:

- Allegro, gas-cooled fast reactor
- LFRSMR, small lead-cooled fast reactor
- LWRSMR, small light water reactor
- FHR, flouride salt-cooled reactor
- MSRE, the molten salt reactor experiment reactor
- MSDR, the molten salt demonstrator reactor
- MSFR, a fast spectrum molten salt reactor
- SFR, sodium-cooled fast reactor

The detailed description and the acknowledgment of the sources of the Serpent2 input files of the studied designs are given in the monograph "Surveillance and Diagnostics of Next Generation Nuclear Reactors" edited by I. Pazsit, H. N. Tran and Zs. Elter (publisher: The Institution of Engineering and Technology, 2025).

The compressed file contains 8 JSON files with the same format. The units of the values are in cm for cross section and size related quantities and the energy units are in MeV. Below we have highlighted the related output parameters from Serpent2 in brackets. The indices 1 and 2 always refer to group 1 and 2. The keys in the JSON files are the following:

- "description": Short information on the reactor design
- "Type": ID of the reactor type.
- "H": Height of the active core
- "R": Equivalent radius of the active core
- "D1" and "D2": Diffusion coefficient (INF_DIFFCOEF)
- "nuSig1" and "nuSig2": Fission neutron production cross section (INF_NSF)
- "Siga1" and "Siga2": Absorption cross section (INF_ABS)
- "SigR1" and "SigR2": Removal cross section (INF_REMXS)
- "Sig1" and "Sig2": Total cross section (INF_TOT)
- "beta0": Total physical delayed neutron fraction (FWD_ANA_BETA_ZERO)
- "lambda": Total delayed neutron precursor decay constant (FWD_ANA_LAMBDA)
- "v1" and "v2": Neutron speed (1/INF_INVV)
- "Chi1" and "Chi2": Total fission spectrum (INF_CHIT)
- "Chi1p" and "Chi2p": Prompt neutron fission spectrum (INF_CHIP)
- "Chi1d" and "Chi2d": Delayed neutron fission spectrum (INF_CHID)
- "Eg": Group boundary between group 1 and 2