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Master's Thesis
Author of thesis: Ing. David Mareček
Acad. year: 2025/2026
Supervisor: Ing. Jitka Vojáčková
Reviewer: Ing. Martin Bárta
This diploma thesis focuses on the validation of the stochastic transport code Serpent 2 for fuel depletion calculations in VVER-440 type reactors. In the practical part, a 3D computational model of an isolated VVER-440 V-179 fuel assembly was developed. A sensitivity analysis evaluating the impact of twelve input parameters on the stability and accuracy of the calculation was performed on this model, resulting in an optimized configuration. Final simulations were conducted using four nuclear data libraries (ENDF/B-VII.1, ENDF/B-VIII.1, JEFF-3.2, and JENDL-4.0). By comparing the calculated isotopic concentrations with experimental data from the international SFCOMPO 2.0 database, a systematic axial shift in local burnup was identified, caused by neglecting the influence of the surrounding assembly environment within the "infinite lattice" boundary conditions. This effect was successfully compensated for by aver-aging the material balance of the assembly, allowing the model to achieve agreement with ex-perimental data within 10% for the majority of the monitored nuclides. Furthermore, the thesis identified systematic measurement errors in the SFCOMPO database for neptunium, europium, and gadolinium isotopes and revealed the potential presence of reprocessed uranium in the ini-tial fuel composition of the investigated assembly. Regarding nuclear data, the JENDL-4.0 and ENDF/B-VII.1 libraries provided the most consistent results, whereas the ENDF/B-VIII.1 library showed local improvement for uranium isotopes, and the JEFF-3.2 library achieved the highest accuracy in predicting plutonium isotopes. Due to formal requirements for the validation process, it is not possible to declare the code officially validated solely on the basis of this work. Nevertheless, the results of this thesis provide a comprehensive methodological foundation for further development of 3D simulations.
Serpent 2, Monte Carlo, validation, nuclear fuel burnup, VVER-440, SFCOMPO 2.0, sensitivi-ty analysis, nuclear data, nuclear data libraries.
Date of defence
11.06.2026
Result of the defence
Defended (thesis was successfully defended)
Grading
A
Process of defence
Student seznámil zkušební komisi s výsledky své diplomové práce. Vedoucí práce Ing. Vojáčková seznámila komisi s posudky vedoucího i oponenta. Studentem byla odpovězena otázka oponenta práce. Následnou rozpravu zahájil předseda komise prof. Katovský. Doplňující otázky položil doktor Radil, na kterého návazal prof. Katovský. Student pohotově odpovídal na předložené dotazy.
Language of thesis
Czech
Faculty
Fakulta elektrotechniky a komunikačních technologií
Department
Department of Electrical Power Engineering
Study programme
Nuclear Power Engineering (MPC-JAE)
Composition of Committee
prof. Ing. Karel Katovský, Ph.D. (předseda) Ing. Štěpán Foral, Ph.D. (místopředseda) Ing. Lukáš Radil, Ph.D. (člen) Ing. Petr Kracík, Ph.D. (člen) doc. Ing. Marek Baláš, Ph.D. (člen) doc. Ing. Pavel Zácha, Ph.D. (člen) Ing. Ota Fišera, Ph.D. (člen)
Supervisor’s reportIng. Jitka Vojáčková
Grade proposed by supervisor: A
Reviewer’s reportIng. Martin Bárta
Grade proposed by reviewer: A
Responsibility: Mgr. et Mgr. Hana Odstrčilová