Calculation of kinetic parameters of LFR with the OpenMC Monte Carlo code : master’s thesis

Olivares, Darian Andrés (author), Hyvärinen, Juhani (mentor), Ambrožič, Klemen (comentor)

This work investigates the different methods used to analyze the effective delayed neutron fraction, $\beta_{eff}$, and the effective mean generation time, $\Lambda_{eff}$, in the OpenMC code, with a particular focus on Lead-cooled Fast Reactors. The document centres on the implementation of the Iterated Fission Probability (IFP) method in OpenMC. A detailed examination of the theory behind the method, along with the sources of uncertainty, is provided to improve understanding and optimize the method. The IFP method is verified and validated by running simulations and comparing their accuracy with experimental data and other commonly used methods for calculating kinetic parameters. These values are computed for a set of fast neutron reactor facilities that are used as benchmarks by various organizations. In general terms, the IFP method demonstrates correct behavior for this type of calculation, achieving consistent results (less than 10% of relative deviation) that agree with benchmarks and other references and showing good adaptation to optimization (number of latent generations, propagation of incertitude).

• Language: English
• Keywords: nuclear engineering, kinetic parameters, lead-cooled fast reactors, OpenMC Monte Carlo code
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Place of publishing: Lappeenranta
• Publisher: D. A. Olivares
• Year: 2025
• Number of pages: 1 spletni vir (1 datoteka PDF ([71] str.))
• PID: 20.500.12556/RUL-172580
• UDC: 621.039
• COBISS.SI-ID: 248211459
• Publication date in RUL: 09.09.2025

Secondary language

• Language: Slovenian

Abstract

V tem delu raziskujemo različne metode, ki se uporabljajo za analizo efektivnega deleža zakasnelih nevtronov, $\beta_{eff}$, in efektivnega povprečnega življenskega časa, $\Lambda_{eff}$, s programom OpenMC, s posebnim poudarkom na hitrih reaktorjih, hlajenih s svincem (LFR). V tem dokumentu se osredotočimo na uporabo metode Iterativne Fissijske vrjetnosti (ang. Iterative Fission Probability - IFP) s programom OpenMC. V tem delu predstavimo teoretično ozadje, predstavimo metodo in njeno optimizacijo in propagacijo negotovosti. Rezultate pridobljene z metodo IFP smo verificirali in validirali z merskimi rezultati in drugimi, pogosto uporabljenimi metodami za izračun kinetičnih parametrov. Te vrednosti so izračunane za niz jedrskih reaktorjev, ki delujejo s hitrimi nevtroni, ki jih različne organizacije uporabljajo kot referenčne vrednosti. Na splošno metoda IFP kaže pravilno delovanje za to vrsto izračunov, saj dosega dosledne rezultate (manj kot 10% relativnega odstopanja), ki se ujemajo z referenčnimi vrednostmi in drugimi viri, ter izkazuje dobro prilagoditev optimizaciji (število latentnih generacij, širjenje negotovosti).

• Keywords: jedrska tehnika, jedrski reaktorji, kinetični parametri, program OpenMC