6._BN800_ICPPA_EN_highlighted-3

1.

8th INTERNATIONAL CONFERENCE ON PARTICLE PHYSICS AND ASTROPHYSICS
Effect of MOX Fuel Loading on the Antineutrino
Emission of the BN-800 Fast Reactor
Valerie Vakulenko
National Research Centre “Kurchatov Institute”
National Research Nuclear University MEPhI
2026

2.

Motivation and Goal
MOTIVATION
Limited Research
Plutonium-dominated
fission
Closed Fuel Cycle
Development
Antineutrino
Monitoring Potential
Reactor antineutrino spectra have mainly been studied for thermal
reactors, including MOX fuel effects and burnup evolution (Hayes et al.,
2012; Jaffke & Huber, 2017; Bernstein et al., 2018). Fast-reactor studies
remain limited. Cogswell & Huber (2016), for example, did not consider
antineutrino spectrum evolution during fuel burnup.
In the fully MOX-loaded BN-800 core, ²³⁹Pu accounts for ~82% (as will be
shown below) of fissions, offering opportunities for future experimental
studies of the ²³⁹Pu fission antineutrino spectrum.
The use of MOX fuel in BN-800 provides a reference for future
antineutrino studies of fast-reactor fuel cycles involving minor-actinide
transmutation.
Studying the effects of MOX fuel loading and burnup on antineutrino
fluxes and spectra provides a basis for assessing thermal power and fuel
isotopic composition monitoring.
Calculate the antineutrino fluxes and energy spectra of the BN-800 reactor for different MOX fuel
GOAL loadings, investigate their evolution during fuel burnup, and compare the results with those of
thermal reactors.
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3.

BN-800 and VVER-1000
Reactor characteristics
PARAMETER
BN-800
VVER-1000
Neutron energy
≈0.1–10 MeV
≈0.01–0.1 eV
MOX* fuel + UO₂ fuel
UO₂ fuel
Uranium fuel with 18.5–24% ²³⁵U enrichment,
3–5% ²³⁵U enrichment
Fuel loading
depending on core position
13th fuel cycle, Kalinin NPP
Thermal power
2,100 MW
3,000 MW
Fuel cycle length
≈200 EFPD*
≈500 EFPD*
*MOX
Mixed uranium dioxide (UO₂) and plutonium dioxide (PuO₂) fuel
* EFPD = effective full-power days
Thermal power: All data were normalized to the BN-800 thermal power (2100 MW).
Fuel cycle: Identical intervals of 198 effective full-power days (EFPD) were considered
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4.

KIR-С Monte Carlo Code and BN-800 Core Model
KIR-С Monte Carlo Code
BN-800 Core Model
KIR-С uses Monte Carlo simulation for steady-state
Fuel assemblies
1,233 homogenized
and transient neutron transport.
Thermal power
2,100 MWth (constant)
Cycle duration
198.16 days
Three-dimensional
geometry
supports
homogeneous and heterogeneous media.
data from international libraries.
Fuel, structural materials and coolant are averaged
within elementary core volumes.
The nuclide kinetics module models fuel burnup
Burnup schedule: 30 time steps
Individual neutron histories use evaluated nuclear
using fission-product yields, radioactive decay data
and neutron-induced reaction pathways.
Белоусов В.И., Иоаннисиан М.В. и др. Программный комплекс КИР
и его возможности. — ВАНТ. Сер. Ядерно-реакторные константы,
2025, вып. 2, с. 66—79.
Period
Steps
Step size
First 10 days
10
1 day
Next 188.16 days
20
9.408 day
Simulation output: fission and neutron-capture rates resolved in space and time.
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Antineutrino Flux Calculation Method
D = 256 см
Detector
rk
k-th core
element
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Fission and Neutron-Capture Rates in BN-800
Campaign-average fission fractions (%)
Campaign-average capture fractions (%)
Fission rates (top) and capture rates (bottom)
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Antineutrino energy spectra comparison with VVER-1000
Antineutrino spectrum per fission
Integrated difference (%) between the end-ofcycle and beginning-of-cycle antineutrino
spectra for BN-800 and for VVER-1000.
Fission fractions
Antineutrino spectra at the midpoint of the BN-800
reactor fuel cycle with 100% MOX fuel loading.
Relative changes in the antineutrino spectra for
different MOX fuel loading at the beginning (solid
lines) and end (dashed lines) of the fuel cycle.
100% MOX: ~40% difference at 6.5 MeV (start)
BN-800: < 2–3% change during the cycle.
VVER-1000: up to ~7% above 6.5 MeV.
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Antineutrino Flux: BN-800 Results
BN-800 flux evolution (100% MOX)
(BN-VVER)/BN,%
MOX loading effect
Comparison with VVER-1000
Fuel-cycle evolution
Increasing BN-800 MOX loading from
16% to 100% reduces the total
antineutrino flux by ~10%, and the flux
above 1.806 MeV by ~20%.
At 100% MOX, the BN-800 flux above
the IBD threshold is ~16% lower than
that of VVER-1000, normalized to the
same 2100 MW thermal power.
The BN-800 flux varies only slightly
over the modeled ~198 EFPD
campaign. The upper plot shows the
weak time dependence of its
components.
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9.

Conclusion
MOX fuel loading effect
The antineutrino flux and energy spectrum of BN-800 change significantly
as MOX fuel loading increases from 16% to 100%.
Redistribution of reaction Increasing MOX loading redistributes ²³⁵U and ²³⁹Pu fission and neutroncapture rates, reducing the antineutrino flux above the IBD threshold by
rates
approximately 20%.
Energy spectrum
differences
Differences between antineutrino spectra for different MOX loadings
increase with energy, reaching tens of percent above 6.5 MeV.
Weak fuel-cycle evolution The antineutrino energy spectrum changes by less than 3% throughout
the fuel cycle for all considered MOX loadings.
Reactor monitoring
potential
The total antineutrino emission rate of BN-800 varies less during the fuel
cycle than that of VVER reactors, making it promising for long-term, noninvasive reactor power monitoring.
Белоусов В. И. и др. Поток и спектр антинейтрино реактора БН800 со смешанной загрузкой // ВАНТ. Сер. Физика ядерных
реакторов. – 2025. – Вып. 2. – С. 4–11.
Белоусов В. И. и др. Влияние концентрации МОКС-топлива на
характеристики нейтринного излучения реактора БН-800 //
ВАНТ. Сер. Физика ядерных реакторов. — Вып. 5 (в печати).
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