Publications de Daniel Jerôme Siefman

On data assimilation with Monte-Carlo-calculated and statistically uncertain sensitivity coefficients

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

Sensitivity coefficients from Monte Carlo neutron transport codes have uncertainties that can affect nuclear data adjustments with integral experiments. This paper presents an extended version of Generalized Linear Least Squares (GLLS), called xGLLS, that ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Data assimilation of post-irradiation examination data for fission yields from GEF

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin, Dimitri Rochman

Nuclear data, especially fission yields, create uncertainties in the predicted concentrations of fission products in spent fuel which can exceed engineering target accuracies. Herein, we present a new framework that extends data assimilation methods to bur ...

EDP SCIENCES S A2020

Data assimilation of post irradiation examination experiments to adjust fission yields

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

Nuclear data, especially fission yields, create uncertainties in the predicted concentrations of fission products in spent fuel. Herein, we present a new framework that extends data assimilation methods to burnup simulations by using data from post-irradia ...

E D P SCIENCES2020

Applying SHARK-X to perform data assimilation with the LWR-PROTEUS Phase II integral experiments

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

Data assimilation methods have recently been implemented in the sensitivity analysis and uncertainty quantification tool SHARK-X. This paper presents how they were used with sensitivity coefficients and randomly-sampled nuclear data to simulate integral pa ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Artificial Neural Networks as Surrogate Models for Uncertainty Quantification and Data Assimilation in 2-D/3-D Fuel Performance Studies

Andreas Pautz, Daniel Jerôme Siefman, Alessandro Scolaro, Mathieu Hursin, Carlo Fiorina

This paper preliminarily investigates the use of data-driven surrogates for fuel performance codes. The objective is to develop fast-running models that can be used in the frame of uncertainty quantification and data assimilation studies. In particular, da ...

2020

Templating colloidal sieves for tuning nanotube surface interactions and optical sensor responses

Daniel Jerôme Siefman, Ardemis Anoush Boghossian, Shang-Jung Wu, Benjamin Paul Johanès Gabriel Lambert, Alice Judith Gillen

Surfactants offer a tunable approach for modulating the exposed surface area of a nanoparticle. They further present a scalable and cost-effective means for suspending single-walled carbon nanotubes (SWCNTs), which have demonstrated practical use as fluore ...

2019

Development and Application of Data Assimilation Methods in Reactor Physics

Daniel Jerôme Siefman

Simulations of nuclear reactor physics can disagree significantly from experimental evidence, even when the most accurate models are used. An important part of this bias from experiment is caused by nuclear data. The nuclear data have inherent uncertaintie ...

EPFL2019

Stochastic vs. sensitivity-based integral parameter and nuclear data adjustments

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin, Dimitri Rochman

Developments in data assimilation theory allow to adjust integral parameters and cross sections with stochastic sampling. This work investigates how two stochastic methods, MOCABA and BMC, perform relative to a sensitivity-based methodology called GLLS. St ...

SPRINGER HEIDELBERG2018

Convergence Analysis and Criterion for Data Assimilation with Sensitivities from Monte Carlo Neutron Transport Codes

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

Sensitivity coefficients calculated with Monte Carlo neutron transport codes are subject to statistical fluctuations. The fluctuations affect parameters that are calculated with the sensitivity coefficients. The convergence study presented here describes t ...

ANS2018

Design of Separated Element Reflector Experiments in CROCUS: PETALE

Pavel Frajtag, Andreas Pautz, Daniel Jerôme Siefman, Vincent Pierre Lamirand, Mathieu Hursin

The present article describes the preliminary design studies for PETALE (Programme d'Etude en Transmission de l'Acier Lourd et ses Elements), an oncoming experimental program in the CROCUS reactor. Within the framework of the Venus-Eole-Proteus collaborati ...

ASTM INTERNATIONAL2018

Analysis of reactivity worths of burnt PWR fuel samples measured in LWR-PROTEUS Phase II using a CASMO-5 reflected-assembly model

Hakim Ferroukhi, Daniel Jerôme Siefman, Mathieu Hursin

The reactivity loss of PWR fuel with burnup has been investigated experimentally by measuring the reactivity worths of highly-burnt fuel samples in a PWR test lattice in the framework of the LWR-PROTEUS Phase II program. Seven UO2 samples cut from fuel rod ...

2017

Case Study of Data Assimilation Methods with the LWR-Proteus Phase II Experimental Campaign

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

This paper describes the application of data assimilation methods to CASMO-5 simulations of a Proteus research reactor experiment. Its focus is a comparison and evaluation of three prominent data assimilation methods: generalized linear least squares, MOCA ...

2017

Neutronics modeling of the CROCUS reactor with SERPENT and PARCS codes

Andreas Pautz, Daniel Jerôme Siefman, Adolfo Rais, Mathieu Hursin

This paper reports the methodology used for the neutronic modelling of the CROCUS reactor and discusses the challenges encountered during the process. Full-core steady-state neutronics solutions were computed with the PARCS code. The Serpent Monte Carlo co ...

2017

Design of Separated Element Reflector Experiments in CROCUS: PETALE

Pavel Frajtag, Andreas Pautz, Daniel Jerôme Siefman, Stefan Radman, Vincent Pierre Lamirand, Mathieu Hursin

The present article describes the preliminary design studies for an oncoming experimental programme at the CROCUS facility. CROCUS is a teaching and research zero-power reactor operated by the Laboratory for Reactor Physics and Systems Behaviour (LRS) at t ...

2017

Full Core modeling techniques for research reactors with irregular geometries using Serpent and PARCS applied to the CROCUS reactor

Gaëtan Girardin, Andreas Pautz, Daniel Jerôme Siefman, Adolfo Rais, Mathieu Hursin

This paper summarizes the results of modeling methodologies developed for the zero-power (100 W) teaching and research reactor CROCUS located in the Laboratory for Reactor Physics and Systems Behavior (LRS) at the Swiss Federal Institute of Technology in L ...

2015

Methods and Models for the Coupled Neutronics and Thermal-Hydraulics Analysis of the CROCUS Reactor at EFPL

Gaëtan Girardin, Andreas Pautz, Daniel Jerôme Siefman, Adolfo Rais, Mathieu Hursin

In order to analyze the steady state and transient behavior of the CROCUS reactor, several methods and models need to be developed in the areas of reactor physics, thermal-hydraulics, and multiphysics coupling. The long-term objectives of this project are ...

2015

Verification of a reactor physics calculation scheme for the CROCUS reactor

Gaëtan Girardin, Andreas Pautz, Daniel Jerôme Siefman, Adolfo Rais, Mathieu Hursin

CROCUS is a zero power (100 W) reactor of the Laboratory for Reactor Physics and Systems Behavior (LRS) at the Swiss Federal Institute of Technology, Lausanne (EPFL). It is used for teaching and research purposes. Its modeling has relied so far on diffusio ...

2014