THE USE OF PULSE TRANSFORMERS WITH FISSION CHAMBERS AND FISSION CHAMBER PREAMPLIFIERS

The question of the spatial distribution of ion pairs created by 235U fission fragments in the active volume of the fission chamber has been studied. The formulas of the spatial distribution of ion pairs in cylindrical fission chambers are proposed, which allows you to evaluate correctly the density of ion pairs in any point in the sensitive volume of the fission chamber

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Characterization and localization of partial-discharge-induced pulses in fission chambers designed for sodium-cooled fast reactors

EPJ Web of Conferences ◽

10.1051/epjconf/201817003002 ◽

2018 ◽

Vol 170 ◽

pp. 03002

Author(s):

G. Galli ◽

H. Hamrita ◽

C. Jammes ◽

M.J. Kirkpatrick ◽

E. Odic ◽

...

Keyword(s):

High Temperature ◽

Neutron Flux ◽

Electrical Discharge ◽

Partial Discharge ◽

Electrical Signal ◽

Fast Reactors ◽

Electrode Gap ◽

Fission Chamber ◽

Flux Monitoring ◽

Fission Chambers

During the operation of the Superphenix and Phenix reactors, an aberrant electrical signal was detected from the fission chambers used for neutron flux monitoring. This signal, thought to be due to partial electrical discharge (PD) is similar to the signal resulting from neutron interactions, and is generated in fission chambers at temperatures above 400 °C. This paper reports work on the characterization and localization of the source of this electrical signal in a High Temperature Fission Chamber (HTFC). The relation between the shape of the PD signal and various parameters (nature and pressure of the chamber filling gas, electrode gap distance, and fission chamber geometry) are first described. Next, experiments designed to identify the location within the chambers where the PD are being generated are presented. After verification and refinement of the results of these localization studies, it should be possible to propose changes to the fission chamber in order to reduce or eliminate the PD signal.

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Test Results of an Innovative and Modular Sensor Design for Fission Chamber Studies

EPJ Web of Conferences ◽

10.1051/epjconf/202022503006 ◽

2020 ◽

Vol 225 ◽

pp. 03006

Author(s):

G. de Izarra ◽

B. Geslot ◽

S. Bréaud ◽

A. Pepino ◽

J-F. Villard ◽

...

Keyword(s):

Calibration Procedure ◽

Electrode Gap ◽

Fission Chamber ◽

Experimental Database ◽

Simulation Tools ◽

Code Validation ◽

Experimental Validations ◽

Chamber Studies ◽

Set Up ◽

Fission Chambers

Since many years, the Instrumentation, Sensors and Dosimetry laboratory at CEA Cadarache has been working to propose innovative and robust design of fission chambers. In this framework, few simulation tools like Chester or PyFc were developed to make detector prototyping and optimisation possible. Up to now, the code experimental validations are scarce mainly because of the lack of flexibility of regular fission chambers. In order to set up an experimental database for code validation, an innovative modular twin fission chamber, the CFTM, was designed. It allows to set with precision the inter-electrode gap, the filling gas pressure as well as the fissile deposit used. This detector was irradiated in Minerve zero power reactor in order to gather results for code validation. Thanks to a calibration procedure, a bank of experimental results is available for simulation validation.

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Fast Neutron-Flux Monitoring Instrumentation for Lead Fast Reactors: A Preliminary Study on Fission Chamber Performances

Volume 6: Nuclear Education, Public Acceptance and Related Issues; Instrumentation and Controls (I&C); Fusion Engineering; Beyond Design Basis Events ◽

10.1115/icone22-31011 ◽

2014 ◽

Cited By ~ 1

Author(s):

Luigi Lepore ◽

Romolo Remetti ◽

Mauro Cappelli

Keyword(s):

Neutron Flux ◽

Fuel Cycle ◽

Fast Reactors ◽

Fission Chamber ◽

Enhanced Sensitivity ◽

Flux Monitoring ◽

Preliminary Study ◽

Fast Flux ◽

Absolute Measurements ◽

Fission Chambers

Although Sodium Fast Reactors (SFRs) are the most investigated solutions for the future fast-flux facilities so far, Lead Fast Reactors (LFRs) promise to be a very competitive alternative thanks to their peculiarity concerning coolant-safety, fuel cycle and waste management. Nevertheless, the development of LFRs presents today some drawbacks still to be solved. Due to the harder neutron flux, the current instrumentation developed for SFRs is likely to be extended to LFRs as a first attempt. Otherwise, new monitoring instrumentation could be developed in order to assure more tailored results. Different measurement technologies can be considered for fast flux monitoring and flux absolute measurements in order to provide a reliable and quick calibration of the overall reactor neutron instrumentation. The goal of this paper is to study the validity of typical fast reactor fission chamber designs (e.g. SuperPhénix fission chambers), indicating which are the limitations when used in a LFR environment. Afterwards, alternative detector solutions with enhanced sensitivity and response will be proposed.

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COSICAF, a fission chamber simulation tool for academic purposes

EPJ Nuclear Sciences & Technologies ◽

10.1051/epjn/2020011 ◽

2020 ◽

Vol 6 ◽

pp. 49

Author(s):

Grégoire de Izarra

Keyword(s):

Monte Carlo ◽

Nuclear Reactions ◽

Atomic Energy Commission ◽

Heavy Ion ◽

Research Field ◽

Fission Chamber ◽

Ion Interactions ◽

Wide Range ◽

Nuclear Instrumentation ◽

Fission Chambers

Nuclear instrumentation is a complex topic since it involves a wide range of physics phenomena like nuclear reactions, heavy ion interactions with matter, electrostatic, charge creation etc. Understanding and modelling fission chambers is a difficult task usually performed with Monte-Carlo and finite element simulations. Since a few years, analytical and simplified Monte Carlo models were introduced at the French Atomic Energy Commission to easily design detectors. It is proposed here to present the derivation of such model, called COSICAF, for academic purposes; this numerical model provided with this article, will help students and researchers to understand and design fission chambers. To demonstrate the interest and the limitation of proposed work in research field, the model is applied to simulate two real miniature fission chamber designs.

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Calibration of CFUL01 fission chambers in the standard neutron fields of the BR1 reactor at SCK CEN

EPJ Web of Conferences ◽

10.1051/epjconf/202125304025 ◽

2021 ◽

Vol 253 ◽

pp. 04025

Author(s):

Anatoly Kochetkov ◽

Antonín Krása ◽

Luc Borms ◽

Edouard Malambu ◽

Guido Vittiglio ◽

...

Keyword(s):

Fission Chamber ◽

Main Method ◽

The Third ◽

Beam Interruption ◽

On Line ◽

Standard Neutron ◽

Fission Chambers ◽

Impurity Determination ◽

Thermal Neutron Spectrum

Recent subcritical VENUS-F experiments showed that fission chambers with a threshold deposit like U-238 can essentially improve the on-line sub-criticality measurments with the beam interruption method, which is currently supposed to be the main method for the ADS MYRRHA. To suppress the uncertainty caused by fissions in the U-235 impurities, the fraction of U-235 in the U deposit should be accurately known. Three PHOTONIS CFUL01 type fission chambers with U-238 deposit were purchased for sub-critical experiments in the VENUS-F reactor. To verify the purity of their deposits, the effective U-235 masses were measured in the empty cavity of the BR1 reactor with a well-known thermal neutron spectrum. It turned out that the measured effective U-235 mass in two fission chambers is lower than the declared mass (as it should be), but this is not the case for the third fission chamber. Then, the effective U-238 mass in these FCs was measured in the well-known fast spectrum of the MARK-III convertor in the BR1 reactor. Finally, the isotopic composition was obtained and it was found that the purity of two CFUL01 FCs is in agreement with the values declared in the certificates but it is not the case for the third fission chamber. As the length of the deposit is bigger than the length of the MARK-III convertor, necessary corrections were calculated with MCNP. The developed procedure using the BR1 standard irradiation fields can be applied for calibration and impurity determination of large fission chambers.

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