Publications de Oskari Ville Pakari

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Noise analysis applied to nuclear reactor physics is a powerful tool to investigate a reactor's kinetic parameters, and more generally underlying physical processes determining core behavior. The kinetic parameters are the coefficients of simplified time-d ...

Analyzing neutron noise in zero-power reactors provides information about integral parameters, such as the prompt decay constant

\alpha

alpha. This information can be used to validate codes that predict said parameters, or time-dependent behavior, part ...

This article presents the development, full-characterization, and in-core testing of a miniature neutron detector for the investigation of highly localized in-core neutronics effects in the zero-power reactor CROCUS, operated at the Ecole Polytechnique fed ...

This article presents the results of an experimental campaign in the CROCUS zero power reactor aimed at investigating the spatial effects of neutron noise measurements. Neutron noise measurements offer a non-invasive method to determine kinetic reactor par ...

The possibility of measuring the gas-phase velocity in a two-phase mixture through the use of neutron noise techniques is demonstrated in the zero-power reactor CROCUS of the Ecole Polytechnique Federale de Lausanne. It is the first step toward the experim ...

This paper is an overview of developments and results regarding neutron noise measurements in current mode at the CROCUS zero power facility. Neutron noise measurements offer a noninvasive method to determine kinetic reactor parameters such as the prompt d ...

Noise measurements in light water reactor systems aid in generating validation data for integral point kinetic parameter predictions and generating monitoring parameters for reactor safety and safeguards. The CROCUS zero-power reactor has been used to supp ...

Analyzing neutron noise in zero power reactors is a valuable tool for gaining insights into integral parameters, such as the prompt decay constant α. This information can be used to validate codes that predict said parameters, or time-dependent behavior, p ...

We experimentally demonstrate the advantages of gamma detection for noise measurements to deter-mine the prompt neutron decay constant a of a nuclear reactor using the power spectral density (PSD) method, coupled to a new uncertainty estimation scheme base ...

In response to the need for validating high-fidelity deterministic neutronics solvers capable of providing pin-resolved neutron flux distributions, intra-pin reaction rates measurements were performed in the CROCUS experimental reactor. A specially designe ...

An advanced neutron detection system for highly localized measurements in nuclear reactor cores was developed and tested in the Laboratory for Reactor Physics and System Behaviour (LRS) at the Ecole polytechnique federale de Lausanne (EPFL), Switzerland, i ...

Gamma rays in nuclear reactors, arising either from nuclear reactions or decay processes, significantly contribute to the heating and dose of the reactor components. Zero power research reactors offer the possibility to measure gamma rays in a purely neutr ...

In the present article, we detail the method used to experimentally determine the power of the CROCUS zero-power reactor, and to subsequently calibrate its ex-core monitor fission chambers. Knowledge of the reactor power is a mandatory quantity for a safe ...

This article presents the development of a neutron noise calculation technique with a reduced calculation time based on the TFM (Transient Fission Matrix) approach. The latter contains different information such as the system transfer function (fission and ...

We report in the present article on the successful observation using noise analysis of the lateral oscillation of one fuel rod by +/- 2.5 mm around nominal at 0.1 Hz frequency, using an mm(3) miniature neutron scintillator at the rod level, and a BGO gamma ...

Gamma rays are an inextricable part of a nuclear reactor's radiation field, and as such require characterization for dose rate estimations required for the radiation protection of personnel, material choices, and the design of nuclear facilities. Most comm ...

The present article gives an overview of the first experimental campaigns carried out in the AKR-2 and CROCUS reactors within the framework of the Horizon 2020 European project CORTEX. CORTEX aims at developing innovative core monitoring techniques that al ...

The advancement of high-fidelity nuclear reactor simulation methods is essential for reducing conservatism in safety margins and optimizing reactor design and operation. This work evaluates the predictive capabilities of the deterministic solvers GeN-Foam ...

This paper presents the development and application of an event tracking feature within the OpenMC Monte Carlo code, designed for advanced neutron spectroscopy and scatter camera system simulations. The newly implemented feature enables the tracking of ind ...

Generative AI tools (often abbreviated genAI or GAI), such as chatGPT, have arguably great potential to induce a paradigm shift in knowledge work.Herein, we present the results of a survey conducted within the nuclear engineering professional community to ...

Oskari Ville Pakari

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Experimental and numerical study of stochastic branching noise in nuclear reactors

Measurement of the Prompt Neutron Decay Constant in a Zero-Power Reactor Using a Novel 3D Detector System

A mm(3) Fiber-Coupled Scintillator for In-Core Thermal Neutron Detection in CROCUS

Investigation of spatial effects on neutron noise measurements in the zero power reactor CROCUS

Measurement of the Gas Velocity in a Water-Air Mixture in CROCUS Using Neutron Noise Techniques

Kinetic Parameter Measurements in the CROCUS Reactor Using Current Mode Instrumentation

Neutron-Gamma Noise Measurements in a Zero-Power Reactor Using Organic Scintillators

Measurement of the Prompt Decay Constant in a Zero Power Reactor Using a Novel 3D Detector System

High accuracy measurement of the prompt neutron decay constant in CROCUS using Gamma Noise and bootstrapped uncertainties

Intra-pin Reaction Rate Measurements in the CROCUS Experimental Reactor

Developing and testing a miniature fiber-coupled scintillator for in-core neutron counting in CROCUS

First in-core gamma spectroscopy experiments in a zero power reactor

Power calibration methodology at the CROCUS reactor

Fast simulation of neutron noise using the Transient Fission Matrix approach and validation on the CROCUS reactor

Local and high distance neutron and gamma measurements of fuel rods oscillation experiments

Delayed gamma fraction determination in the zero power reactor CROCUS

Neutron noise experiments in the AKR-2 and CROCUS reactors for the European project CORTEX

Comparison of high-fidelity transport code predictions against the NECTAR intra-pin reaction rate measurements

Development of an Event Tracking Feature in OpenMC for Neutron Spectroscopy and Scatter Camera Systems

Generative AI tools in the nuclear engineering community: A survey-based evaluation of the current adoption and impacts