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Bibliographic Details
Main Authors: Bureš, Lubomír, Raffuzzi, Valeria
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.11191
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author Bureš, Lubomír
Raffuzzi, Valeria
author_facet Bureš, Lubomír
Raffuzzi, Valeria
contents We present a stochastic framework for low-population dynamics in circulating-fuel reactors (CFRs) that captures delayed-neutron precursor (DNP) transport without delay terms. Starting from a modified point-kinetics model with two perfectly-mixed volumes, we derive equivalent discrete-event dynamics and an Itô stochastic differential equation (SDE) system. Two solvers are implemented: an analog Monte Carlo (AMC) engine and a semi-implicit Milstein SDE solver. Transient benchmarks demonstrate perfect agreement of AMC/SDE means with deterministic solutions, while revealing that the SDE approach underestimates DNP variances in selected regimes, potentially due to the neglect of DNP noise. We further recast reactivity loss due to precursor drift in this stochastic setting and show that its estimator is negatively biased. Overall, the developed framework provides a minimal yet representative model for CFR low-population kinetics. Future work will re-derive and test SDE noise terms and apply the framework to selected transient applications such as start-up analyses of CFRs.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11191
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stochastic Point Kinetics Model of Circulating-Fuel Reactors under Perfect Mixing Approximation
Bureš, Lubomír
Raffuzzi, Valeria
Computational Physics
We present a stochastic framework for low-population dynamics in circulating-fuel reactors (CFRs) that captures delayed-neutron precursor (DNP) transport without delay terms. Starting from a modified point-kinetics model with two perfectly-mixed volumes, we derive equivalent discrete-event dynamics and an Itô stochastic differential equation (SDE) system. Two solvers are implemented: an analog Monte Carlo (AMC) engine and a semi-implicit Milstein SDE solver. Transient benchmarks demonstrate perfect agreement of AMC/SDE means with deterministic solutions, while revealing that the SDE approach underestimates DNP variances in selected regimes, potentially due to the neglect of DNP noise. We further recast reactivity loss due to precursor drift in this stochastic setting and show that its estimator is negatively biased. Overall, the developed framework provides a minimal yet representative model for CFR low-population kinetics. Future work will re-derive and test SDE noise terms and apply the framework to selected transient applications such as start-up analyses of CFRs.
title Stochastic Point Kinetics Model of Circulating-Fuel Reactors under Perfect Mixing Approximation
topic Computational Physics
url https://arxiv.org/abs/2602.11191