Gérald Rimpault

This paper presents the development of a new method for the Validation process of the new French (CEA) deterministic neutron transport code APOLLO3® developed at CEA with the support of EDF and AREVA. The objective of the APOLLO3® code system is to treat any kind of reactor cores with reference calculation schemes. The main purpose of this work is...

This paper presents the latest advances of the Verification & Validation works achieved within the framework of the new CEA APOLLO3® code project. It focusses on the performances of the brand new SFR and LWR assembly calculation routes (representative of ASTRID or EPR cores). Based on the most recent development of the TDT-MOC flux solver and self-...

This paper focusses (within the framework of the V&V process of the new APOLLO3 ® deterministic code) on the use of Machine Learning algorithms (neural network) to estimate computational model errors while solving neutron transport equation. After evaluating the main relevant calculation errors thanks to deterministic vs. stochastic pointwisel/mult...

For the next generation of fast reactors, global objectives are required in terms of safety, sustainability, waste minimization and non-proliferation issues. Concerning safety issues, particular efforts have been made in order to obtain core designs that can be resilient to accidental transients. In that frame, the CEA held R&D program toward a GEN...

JHR is a new material testing reactor under construction at CEA Cadarache. Its high flux core contains 37 fuel assemblies loaded along concentric rings into alveolus of an aluminum matrix. For the operation of the reactor, twenty-seven of these fuel assemblies hovnst hafnium rods in their center while the other ones but also the beryllium radial re...

Sodium-cooled Fast Reactors (SFRs) remain a potential candidate to meet future energy needs. In addition, the SFRs experimental feedback is considerable, for instance, the French research program has considered experimental facilities including the Superphénix which has emerged as a transition to commercial deployment. In this paper a set of tests...

The OECD-NEA High Priority Request List (HPRL) is a point of reference to guide and stimulate the improvement of nuclear data for nuclear energy and other applications, and a tool to bridge the gap between data users and producers. The HPRL is application-driven and the requests are submitted by nuclear data users or representatives of the user's c...

The OECD-NEA High Priority Request List (HPRL) is a point of reference to guide and stimulate the improvement of nuclear data for nuclear energy and other applications, and a tool to bridge the gap between data users and producers. The HPRL is application-driven and the requests are submitted by nuclear data users or representatives of the user's c...

For the next generation of fast reactors, global objectives are required in terms of safety, sustainability, waste minimization and non-proliferation issues. Concerning safety issues, particular efforts have been made in order to obtain core designs that can be resilient to accidental transients. In that frame, the CEA held R&D program toward a GEN...

The objective of this work is to revisit integral data assimilation for a better prediction of the characteristics of SFR cores. ICSBEP, IRPhE and MASURCA critical masses, PROFIL irradiation experiments and the FCA-IX experimental programme (critical masses and spectral indices) with well-mastered experimental technique have been used. As calculati...

The Superphénix reactor remains the largest Sodium-cooled Fast Reactor (SFR) ever built in the world and its legacy is a unique source of information for SFRs. At the Superphénix start-up, a series of tests (Transversal Irradiation tests) were devoted to the core flux distribution with measurements in several assembly positions located from the cor...

The Superphénix reactor was a Sodium-cooled Fast Reactor (SFR) developed under a European framework that intended to provide a general design of a commercial power plant. During the start-up of the reactor, six different batches containing dummy assemblies allowed to verify the main safety criteria at zero-power conditions tests at 180°C. The prese...

Generation IV reactors are expected to exhibit significant safety improvements compared to current ones. In sodium-cooled fast reactors (SFRs), fuel melting during transient over power (TOP) should be avoided as this is identified as a relatively frequent accident. Among these TOP accidents, a control rod withdrawal (CRW) accident is the most likel...

Nuclear data evaluations on major actinides can be improved by integral data assimilation. Appropriate integral measurements with reliable experimental techniques have been selected such as ICSBEP, IRPhE and MASURCA critical masses, PROFIL irradiation experiments and the FCAIX experimental programme (critical masses and spectral indices). Highly re...

In a Sodium Fast Reactor (SFR), neutronic quantities are significantly modified through burn-up, not only the reactivity swing but also feedback coefficients such as Sodium Void Re-activity Worth or Doppler Effect. These core quantities need to be precisely known through the whole cycle, for safety considerations. The decay chain used in determinis...

High accuracy neutronic simulations are required for the development of Generation-IV sodium cooled fast reactors (SFR). This paper therefore focuses on the development and validation of an improved calculation method in APOLLO3® deterministic code to predict the reactivity control system in SFR. This method relies on the “lattice-core” paradigm...

In the heterogeneous minor actinides transmutation approach, the nuclei to be transmuted are loaded in dedicated targets often located at the core periphery, so that long-lived heavy nuclides are turned into shorter-lived fission products by fission. To compensate for low flux level at the core periphery, the minor actinides content in the targets...

An OECD/NEA sub-group on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been formed under the NSC/WPRS/EGUAM to check the use of best-estimate codes and data. This work comes from the desire to design reactors with improved safety performance while preserving a sustaina...

An OECD/NEA subgroup on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been formed under the NSC/WPRS/EGUAM to check the use of best-estimate codes and data. This work comes from the desire to design reactors with improved safety performance while preserving a sustainab...

Heterogeneous minor actinides transmutation is the process of loading neptunium, americium and curium in dedicated targets, generally located at the core periphery, in order to transmute these long-lived heavy nuclides into shorter-lived fission products. This has a positive effect on long-term radiotoxicity of the spent fuel and on the short to me...

Minor actinides transmutation is the process of decreasing the long term radiotoxicity of the nuclear spent fuel by submitting it to a neutron flux so as to achieve fission of the heavy nuclides concerned. In the case of a closed fuel cycle, minor actinides are the main contributors to the spent fuel radiotoxicity after a few centuries. The isotopi...

In the case of a closed fuel cycle, minor actinides transmutation can lead to a strong reduction in spent fuel radiotoxicity and decay heat. In the heterogeneous approach, minor actinides are loaded in dedicated targets located at the core periphery so that long-lived minor actinides undergo fission and are turned in shorter-lived fission products....

Critical mass calculations of various HEU-fueled fast reactors result in large discrepancies in C/E values, depending on the nuclear data library used and the configuration modeled. Thus, it seems relevant to use integral experiments to try to reassess cross sections that might be responsible for such a dispersion in critical mass results. This wor...

In this paper, we present recent advances on PWR core calculations schemes with the most advanced features of the new deterministic neutronic transport code APOLLO3®. We focus mostly on reactivity effects of control rod sub-assemblies representation. Two kinds of representation are being studied: a representation in which the control rod sub-assemb...

An iterative domain decomposition method (DDM) is implemented inside the APOLLO3 Sn transport core solver MINARET. Based on a block-Jacobi algorithm, the method inherently suffers a convergence penalty in terms of both computing time and number of iterations. An acceleration method has to be developed in order to overcome this difficulty. This pape...

An OECD/NEA subgroup on Uncertainty Analysis in Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been formed under the NSC/WPRS/EGUAM and is currently undertaking preliminary studies after having specified a series of benchmarks. The incentive for launching the SFR-UAM task force comes from the...

One of the tasks of the OECD/NEA subgroup on Uncertainty Analysis in Modeling (UAM) of Sodium-cooled Fast Reactors (SFR-UAM) under the NSC/WPRS/EGUAM is to perform a code-to-code comparison on neutronic feedback coefficients and associated uncertainties calculated for transient analyses. This benchmark exercise benefits from the results of a previo...

The presented work details the SNEAK-12B experimental program, which is under reevaluation in a joint collaboration of CEA/KIT/Ben-Gurion University. In this work a reevaluation of the SNEAK-12B programs is made with the Serpent 2 code, which enables a detailed study of the presented core. The reevaluation was made utilizing two nuclear data evalua...

This paper presents a comparison of homogenization techniques implemented in the APOLLO3 platform for transport core calculations: standard scalar flux weighting and new flux-moment homogenization, in different combinations with (or without) leakage models. Besides the historical B1-homogeneous model, a new B-heterogeneous one has indeed been imple...

The effective delayed neutron fraction (βeff) is an important characteristic of nuclear reactors since it affects transients significantly. It is therefore important to characterise it correctly. The use of best-estimate codes and data together with an evaluation of the uncertainties is required not only for their use in safety studies but also to...

A methodology dedicated to the optimization of the transmutation of minor actinides (MAs) in dedicated blankets is discussed here. This methodology relies on recently developed optimization tools. In the so-called heterogeneous transmutation approach, MAs are loaded into specific assemblies located at the periphery of a fast reactor core. Thus, the...

Heterogeneous loading of minor actinides in radial blankets is a potential solution to implement minor actinides transmutation in fast reactors. However, to compensate for the lower flux level experienced by the blankets, the fraction of minor actinides to be loaded in the blankets must be increased to maintain acceptable performances. This severel...

Heterogeneous loading of minor actinides in radial blankets is a potential solution to implement minor actinides transmutation in fast reactors. However, to compensate for the lower flux level experienced by the blankets, the fraction of minor actinides to be loaded in the blankets must be increased to maintain acceptable performances. This severel...

Minor actinides (MA) transmutation options for critical fast reactors are divided in two different approaches, the homogeneous one in which MA are diluted in the driver fuel and the heterogeneous one in which Ma are concentrated in UO2 based fuel in sub-assemblies located at the periphery of the core. This latter option, named minor actinides beari...

In neutron chain systems with material symmetries, various k-eigenvalues of the neutron balance equation beyond the dominant one may be degenerate. Eigenfunctions can be partitioned into several classes according to their invariance properties with respect to the symmetry operations (mirror symmetries and rotations) keeping the material distributio...

In neutron chain systems with material symmetries, various k-eigenvalues of the neutron balance equation beyond the dominant one may be degenerated. As shown in a companion paper, the power iteration method can be used to compute higher eigenfunctions in symmetric systems, provided that the global problem is partitioned into symmetry class-related...

In neutron chain systems with material symmetries, various k-eigenvalues of the neutron balance equation beyond the dominant one may be degenerate. Eigenfunctions can be partitioned into several classes according to their invariance properties with respect to the symmetry operations (mirror symmetries and rotations) keeping the material distributio...

The new reactor analysis platform APOLLO3R©is under development at CEA and should re-place the current ERANOS code system for Fast Reactor studies. APOLLO3R©proposes newsolvers and advanced numerical methods to be used for all kinds of reactor concepts. At the sametime, CEA is largely involved in the study of the ASTRID project and the CFV core. Th...

Fast reactor designs are being currently revisited aiming at having a consolidated safety dossier. In that frame, studying any perturbation of nominal operating condition is mandatory. Among different initiators, a particular attention is being paid on reactivity insertion due to core assemblies bowing and deformation and induced lattice readjustm...

In reactor physics, calculation schemes with deterministic codes are validated with respect to a reference Monte Carlo code. The remaining biases are attributed to the approximations and models induced by the multigroup theory (self-shielding models and expansion of the scattering law on Legendre polynomials) to represent physical phenomena (resona...

In the framework of the development of the Sodium Fast Reactor technology (SFR) the analysis of all possible scenarios leading to perturbation of nominal operating condition is exploited. Among these scenarios attention is being paid on reactivity modification due to core assemblies bowing and deformation, and to lattice readjustments consequent to...

In the frame of the Working Party on Reactor and System (WPRS), an international mandate has been proposed to work towards a shared neutronic analysis of several Generation-IV Sodium-cooled Fast Reactor (SFR) concepts. This paper summarizes the results obtained for large cores benchmark by participants from numerous institutes of different countrie...

The design of innovative cores for Generation IV Sodium-cooled Fast Reactors (SFRs) must chiefly focus on an improving safety performance levels and competitiveness, with the aim of achieving all fundamental goals set for Generation IV systems. In this context, one priority is to create a core design such that, in the event of a serious accident, a...

Les réacteurs rapides au plomb sont l’un des six concepts retenus par le forum international GIF pour les réacteurs de quatrième génération. Il n’a jamais existé de réacteurs au plomb, mais une filière de réacteurs au plomb-bismuth a été développée par les russes pour la propulsion nucléaire de leurs sous-marins. Cette filière a été abandonnée suit...

The present paper is dedicated to the synthesis of the safety studies carried out on the 2400 MWth gas-cooled fast reactor (GFR2400) concept developed at CEA. The analysis of the reference design basis accidents investigated up to now, has shown margins up to the acceptance criteria, equal at least to 300 °C for the category 3 situations and larger...

The development of accelerator-driven systems (ADSs) is motivated by the potential of these machines to reduce the volume and the radiotoxicity of accumulated nuclear waste, more particularly that of minor actinides currently generated by the operation of existing pressurized water reactors. The reduction of both volume and radiotoxicity of nuclear...

The development of accelerator-driven systems (ADSs) is motivated by the potential of these machines to reduce the volume and the radiotoxicity of accumulated nuclear waste, more particularly that of minor actinides currently generated by the operation of existing pressurized water reactors. The reduction of both volume and radiotoxicity of nuclear...

The effect of temperature changes and in particular those that are accompanied by strong gradients was extensively investigated for fast reactors. Subcritical systems designed for their transmutation ability are to some extent similar to critical power reactors in their subassembly structure. However, they differ in two main aspects. First, the coo...

Designing future Sodium Fast Reactors (SFR) requires enhancing their operational performance and reducing the probability to go into core disruption. As a consequence of these constraints, these novel reactors exhibit rather unusual features compared to past designs. The studies related to the development of a prototype 4 th generation fast neutron...

Sodium cooled Fast Reactors (SFRs) remain the favorite candidate in France for a GEN IV reactor fleet to be deployed within this century. Compared with earlier generations (Phenix, Super-Phenix, EFR), GEN IV SFR requires attractive economics together with enhanced safety and non-proliferation criteria. An innovative approach named METRO (Mathematic...

Sodium-cooled fast reactors (SFRs) remain the favorite candidate in France for a Generation IV (Gen IV) reactor fleet to be deployed within this century. Compared with earlier generations (Phénix, Superphénix, and European fast reactor), Gen IV SFRs require attractive economics together with enhanced safety and nonproliferation criteria. An innovat...

The reactivity effects associated to the mitigation of the Unprotected Loss Of Flow (ULOF) in Sodium Fast Reactors are being studied for finding means to reduce the potential release of mechanical energy. The studies performed with ERANOS illustrate the importance of the cladding removal as well as the radial leakage changes during the core slump-...

Reactivity effects associated with the mitigation of unprotected loss of flow in sodium fast reactors are being studied to find ways to reduce the potential release of mechanical energy. The studies performed with ERANOS illustrate the importance of cladding removal as well as radial leakage changes during the core slumpdown. Possible arrangements...

Designing future Sodium Fast Reactors (SFR) requires enhancing their operational performance and reducing the probability to go into core disruption. As a consequence of these constraints, these novel reactors exhibit rather unusual features compared to past designs. The cores are much larger with rather flat shape. The consequences ofthat shape on...

The local energy photon deposit must be accounted accurately for Gen-IV fast reactors, advanced light-water nuclear reactors (Gen-III+) and the new experimental Jules Horowitz Reactor (JHR). The γ energy accounts for about 10% of the total energy released in the core of a thermal or fast reactor. The γ-energy release is much greater in the core of...

In order to reduce the volume and the radiotoxicity of the nuclear waste coming from the operation of existing pressurized water reactors, Accelerator Driven Systems (ADS) have been envisioned. The EFIT-Pb plant is the first ADS design which has been going into rather detailed engineering level. It is a lead cooled 385 MWth ADS prototype for minor...

In order to reduce the volume and the radiotoxicity of the nuclear waste coming from the operation of existing pressurized water reactors, Accelerator Driven Systems (ADS) have been envisioned. The He-EFIT (Helium cooled European Facility for Industrial Transmutation) concept is the EUROTRANS Project backup option while Pb-EFIT is the reference on...

In order to reduce the volume and the radiotoxicity of the nuclear waste coming from the operation of existing pressurized water reactors, accelerator-driven systems (ADSs) have been envisioned. The Lead-Cooled (Pb) European Facility for Industrial-Scale Transmutation (EFIT) (Pb-EFIT) plant is the first ADS design that has been going into a rather...

In order to reduce the volume and the radiotoxicity of the nuclear waste coming from the operation of existing pressurized water reactors, accelerator-driven systems (ADSs) have been envisioned. The Helium-cooled (He) European facility for Industrial-scale Transmutation (He-EFIT) concept is the EUROpean Research Programme for the TRANSmutation of H...

The ERANOS code and data system has been specified to calculate all neutronic parameters required for the design of a fast reactor. With an appropriate choice of algorithmic options. the ERANOS system is used for shielding applications. The cell code ECCO prepares cross sections in a VITAMIN J group scheme t 175 groups) while the BISTRO code treats...

The adjusted nuclear data library ERALIBl is described in this paper. It is the first step in the process towards a unique data set which will be valid for all applications (core neutronics. shielding, fuel cycle) and for all types of fission reactor (thermal, epithermal. fast). It has been derived from a 1968 group application library based on JEF...

This paper deals with the resolution of the integro-differential form of the Boltzmann transport equation for neutron transport in nuclear reactors. In multigroup theory, deterministic codes use transfer cross sections which are expanded on Legendre polynomials. This modelling leads to negative values of the transfer cross section for certain scatt...

The European Facility for Industrial Transmutation (EFIT) has been developed within the 6th EU Framework by the EUROTRANS Program, aiming at a generic conceptual design of an accelerator driven transmuter. This paper deals with assessments of EFIT cores with CERCER and CERMET fuels from the viewpoint of core performance and safety. The conclusive r...

In 1999, the IAEA has initiated a Coordinated Research Project on “Updated Codes and Methods to Reduce the Calculational Uncertainties of the LMFR Reactivity Effects.” Three benchmark models representing different modifications of the BN-600 fast reactor have been sequentially established and analyzed, including a hybrid core with highly enriched u...

Core disruptive accidents in fast reactors need to be monitored carefully since they may lead to possible criticality configurations. However, the worst-case scenario may have small probability occurrences, but the proof of it requires multidisciplinary studies. Even with the upgrade in computer performance, calculations would require several month...