Research Article 
Corresponding author: Vladimir S. Potapov ( potapovvs@ibrae.ac.ru ) Academic editor: Georgy Tikhomirov
© 2022 Aleksandr A. Belov, Valery P. Bereznev, Galina S. Blokhina, Dmitry P. Veprev , Dmitry A. Koltashev, Vladimir S. Potapov , Olga I. Chertovskikh, Aleksey V. Shershov.
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Citation:
Belov AA, Bereznev VP, Blokhina GS, Veprev DP, Koltashev DA, Potapov VS, Chertovskikh OI, Shershov AV (2022) Simulating a leadcooled reactor campaign using the EUCLID/V1 code. Nuclear Energy and Technology 8(4): 261265. https://doi.org/10.3897/nucet.8.96565

The paper presents the results of the development of the EUCLID/V1 integrated dynamic code designed to analyze and justify the safety of fast neutron reactor facilities with a liquidmetal coolant, in terms of simulating the reactor campaign. The relevance of this study lies in the need to simulate the behavior of the core at any time during the campaign. It lets us to obtain a full dataset for subsequent simulations of the reactor dynamic conditions (including transient states or accidents). The authors have developed a fuel archive to store calculated data in HDF5 format, created a computational model editor to generate input data in the fuel archive format, and also provided an example of computing the campaign of a leadcooled fast reactor for three core design models shown in this paper. The main array of fuel assemblies was simulated as a single unit in the first model, as three units in the second model, and in the third every single assembly was unique. In addition, the authors have shown changes in the total masses of actinides in the core, revealed that the different core models have an insignificant effect on the evolution of the total masses of actinides, and given the fuel assembly burnup values for the three core models. For the third model, the largest difference between the minimum and maximum burnup values was obtained with an almost identical average over the fuel assemblies. The reactivity margin over time for the three core models was presented. It was shown that the values and behavior of the reactivity margin during the three microcampaigns are almost equal. From the fourth to the sixth cycle, the reactivity margin value for the third core model was lower than for the first and the second ones. Finally, the authors conclude that it is desirable to evaluate the behavior of the reactivity margin for leadcooled fast reactor campaigns based on the detailed model of the core.
Fastneutron reactor, reactor campaign, EUCLID/V1, fuel assembly, burnup, BPSD, neutronic parameters
The need for a computational justification of the safety of liquid metal cooled reactor facilities stimulates the development of the modern computational tools that make it possible to simulate various operating modes of a reactor facility throughout its entire life cycle. One of such tools is the integrated code EUCLID/V1 developed at IBRAE. In this paper, we consider the possibilities of using the EUCLID/V1 code for computational simulations of reactor campaigns.
The integrated dynamic universal computer code used for analysis and justification the safety of liquid metal cooled fast neutron reactors, EUCLID/V1, has been developed at the Nuclear Safety Institute (IBRAE) of the Russian Academy of Sciences since 2012, within the framework of the private project on the “New generation codes” of the “PRORYV” project (
The EUCLID/V1 code has a modular structure including three main modules: thermal hydraulic, fuel rod and neutron ones. Neutron calculations in the EUCLID/V1 code are carried out on the base of the DN3D module, which includes diffusion (singlepoint, sevenpoint, and hybrid computation schemes) and kinetic options (based on the discrete ordinate method). The diffusion and kinetic options are based on the use of the DOLCE VITA (
In 2019, work began on modifying the EUCLID/V1 code to enable computations of reactor operating modes, taking into account core burnup and fuel assembly loading, as part of microcampaigns based on the current version of the BPSD program (
Computations of modes, including burnup accounting, are associated with the processing and storage of large amounts of data, which necessitates the use of the fuel archive.
The fuel archive includes data on the parameters of the computational model, fuel assemblies, control and safety devices, material composition of the core, control parameters of the computation, etc.
The computational model editor has user interfaces for easy setting and adjustment of reactor plant parameters (Fig.
To take into account changes in the nuclide composition during the computation of a microcampaign, group crosssections are prepared after each burnup step using the CONSYST program (
To reduce computing costs, the combination of assemblies similar in neutronic and thermohydraulic characteristics in the form of single representatives is used. These representatives are used for further simulation of the core, taking into account sets of averaged parameters. An example of the core loading pattern with representatives of fuel assemblies is shown in Fig.
As an example, let us consider a simulated campaign of a leadcooled reactor plant lasting 900 days. The campaign is divided into 6 microcampaigns of 150 effective days, each with stops for 30 days.
The first core loading pattern with oblique numbering of fuel assemblies is shown in Fig.
During the campaign, some permanent reactivity compensators and fuel assemblies are rearranged. At the same time, the temperature distributions of the materials throughout the entire computation are set constant.
Three computations of the reactor campaign with different partitions were carried out for fuel assemblies in the central and peripheral zones without the CPS actuators (CZ FAs and PZ FAs) (Table
For the CZ FAs and PZ FAs, burnup values were obtained at the end of the sixth microcampaign (Table
Assembly  Option 1  Option 2  Option 3 

CZ FAs  
Average  4.023  4.023  4.024 
Minimum  –  3.5324  3.0837 
Maximum  –  4.7501  4.7622 
PZ FAs  
Average  2.4749  2.4748  2.4745 
Minimum  –  –  1.7965 
Maximum  –  –  3.1941 
For ^{235}U, ^{238}U, ^{238}Pu, ^{239}Pu, ^{240}Pu, ^{241}Pu, ^{242}Pu, and ^{241}Am the time dependences of changes in the total masses of nuclides in the core were obtained. Figs
The mass changes over the entire core are practically independent of the type of partitioning. It is explained by the fact that the total power of the reactor is constant throughout the entire computation for all the options, that is, the total energy released in the core during the interaction of neutrons with nuclei does not depend on the type of model partitioning. At the same time, the burnup distributions for the fuel assemblies in the different partitioning options differ (Fig.
The timereactivity margin curve for the three options is also presented (Fig.
The results presented in Fig.
The EUCLID/V1 code implements the technology for computing simulated reactor plant campaigns using the nuclide kinetics code BPSD, including a core constructor and support for an archive of states in HDF5 format with a library of access functions.
A series of computations of a leadcooled reactor plant simulated campaign was carried out. The results obtained were used as part of the work to improve the computing method, as well as to refine the functionality of the code.
Further work is aimed at improving the preprocessing tools, computational algorithms, and the core state archive format. In subsequent computations, it is planned to use the thermal hydraulic and fuel rod modules of the EUCLID/V1 code to take into account the effect of temperaturedensity feedbacks on the neutronic characteristics during the entire campaign.
The work was carried out with the financial support of the State Corporation Rosatom (within the framework of State Contracts No. N.4o.241.19.20.1027 dated March 20, 2020 and No. N.4o.241.19.21.1068 dated April 14, 2021).