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RSICC CODE PACKAGE CCC-880

1.         NAME AND TITLE

FIFRELIN-1.7: Generation of fission fragments and simulate their de-excitation to estimate prompt fission observables.

Axillary Programs (NOT INCLUDED): GEF code can be used in connection for producing primary fission fragment pre-neutron input data (mass yields, as well as charge yields and kinetic energy distributions. In addition, FIFRELIN can generate input file for PHITS/DCHAIN system code to calculate decay heat using fission product yields.

2.         CONTRIBUTORS

CEA, DEN, DER, F-13108 Saint-Paul-Lez-Durance, France; via the OECD NEA Data Bank, Boulogne-Billancourt, France. (NEA-1934/01)

3.         CODING LANGUAGE AND COMPUTER

C++; Linux OS executable only (RSICC ID: C00880MNYWS00).

4.         NATURE OF PROBLEM SOLVED

The FIFRELIN code is a Monte Carlo implementation of the Becvar's notion of Nuclear Realization extended to neutron/gamma/electron emission (similar to the statistical Hauser-Feshbach nuclear reaction theory) applied to the de-excitation of primary fission fragments. It provides full kinematic information on the two final fission products of a binary fission as well as the emitted neutrons, photons and conversion electrons. Ascii files are provided along with an event tree containing the whole set of particle characteristics (useful for detector simulation). The input for FIFRELIN is the pre-neutron fission mass distributions and the average kinetic energy per mass. The RIPL-3 nuclear structure database is used at low excitation energy to construct the nuclear level schemes accounting for energy, spin, parity, half-life and branching ratio. These level schemes are completed by nuclear models at higher energy levels. This release treats spontaneous fission and neutron induced fission (before second chance fission). In addition, the FIFRELIN code can be used for de-exciting any kind of nucleus by neutron/gamma/electron emission, initial state E,J,pi being provided by the user. [1]

5.         METHOD OF SOLUTION

Monte Carlo method / Becvar's algorithm (nuclear realization) extended to coupled neutron/gamma/electron emission.

6.         RESTRICTIONS OR LIMITATIONS

Can be time consuming, related to the construction of nuclear realizations for fission fragments.

7.         TYPICAL RUNNING TIME

It depends on the fissioning system and the accuracy required for a given observable.
Pu242(sf): 100x500 cascades over 10 threads last 20 min on Intel Xeon Silver 4210R CPU @ 2.4 GHz.
Statistical uncertainty for nubar 0.2% U235(nth,f): 500x2000 cascades over 30 threads last 5 h on Intel Xeon Silver 4210R CPU @ 2.4 GHz. Statistical uncertainty for nubar: 0.04%.

8.         COMPUTER HARDWARE REQUIREMENTS

If a binary tree is requested, depending on the number of histories, disk space can reach dozens of GB

9.         COMPUTER SOFTWARE REQUIREMENTS

Linux Debian 10, 11, 12 or Ubuntu 18, 20, 22. Debian and Ubuntu systems only. For other systems Apptainer and Docker images are provided.

10.        REFERENCES

[1] O. Litaize, A. Chebboubi, V. Piau, P. Tamagno, L. Thulliez, O. Serot: FIFRELIN-1.7 theoretical description and user guide, July 24, 2024.

PSG2 / Serpent - a Quick Installation Guide.

11.        CONTENTS OF CODE PACKAGE

The package is transmitted digitally as a zip file that includes Debian/Ubuntu executables, User Guide. Docker recipe, Apptainer image and ReadMe.

12.        DATE OF ABSTRACT

September 2026

KEYWORDS:        BENCHMARKS, CROSS-SECTIONS, EVALUATION, FISSION, NUCLEAR DATA