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

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.

Download Full-text

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.

Download Full-text

On Capabilities and Limitations of Current Fast Neutron Flux Monitoring Instrumentation for the Demo LFR ALFRED

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4033697 ◽

2016 ◽

Vol 2 (4) ◽

Cited By ~ 2

Author(s):

Luigi Lepore ◽

Romolo Remetti ◽

Mauro Cappelli

Keyword(s):

Monte Carlo ◽

Neutron Flux ◽

Fast Reactor ◽

Nuclear Power ◽

Power Plants ◽

Fuel Cycle ◽

Signal To Noise Ratio ◽

Reactor Power ◽

Fast Reactors ◽

Flux Monitoring

Among GEN IV projects for future nuclear power plants, lead-cooled fast reactors (LFRs) seem to be a very interesting solution due to their benefits in terms of fuel cycle, coolant safety, and waste management. The novelty of this matter causes some open issues about coolant chemical aspects, structural aspects, monitoring instrumentation, etc. Particularly, hard neutron flux spectra would make traditional neutron instrumentation unfit to all reactor conditions, i.e., source, intermediate, and power range. Identification of new models of nuclear instrumentation specialized for LFR neutron flux monitoring asks for an accurate evaluation of the environment the sensor will work in. In this study, thermal hydraulics and chemical conditions for the LFR core environment will be assumed, as the neutron flux will be studied extensively by the Monte Carlo transport code MCNPX (Monte Carlo N-Particles X-version). The core coolant’s high temperature drastically reduces the candidate instrumentation because only some kinds of fission chambers and self-powered neutron detectors can be operated in such an environment. This work aims at evaluating the capabilities of the available instrumentation (usually designed and tailored for sodium-cooled fast reactors) when exposed to the neutron spectrum derived from the Advanced Lead Fast Reactor European Demonstrator, a pool-type LFR project to demonstrate the feasibility of this technology into the European framework. This paper shows that such a class of instrumentation does follow the power evolution, but is not completely suitable to detect the whole range of reactor power, due to excessive burnup, damages, or gamma interferences. Some improvements are possible to increase the signal-to-noise ratio by optimizing each instrument in the range of reactor power, so to get the best solution. The design of some new detectors is proposed here together with a possible approach for prototyping and testing them by a fast reactor.

Download Full-text

Nuclear Instrumentation Systems in Prototype Fast Breeder Reactor

12th International Conference on Nuclear Engineering, Volume 2 ◽

10.1115/icone12-49354 ◽

2004 ◽

Cited By ~ 1

Author(s):

P. M. Vijayakumaran ◽

C. P. Nagaraj ◽

C. Paramasivan Pillai ◽

R. Ramakrishnan ◽

M. Sivaramakrishna

Keyword(s):

Neutron Flux ◽

Early Warning System ◽

Warning System ◽

Radiation Monitoring ◽

Fast Breeder Reactor ◽

Delayed Neutrons ◽

The Core ◽

Flux Monitoring ◽

Nuclear Instrumentation ◽

Fission Chambers

The nuclear instrumentation systems of the Prototype Fast Breeder Reactor (PFBR) primarily comprise of global Neutron Flux Monitoring, Failed Fuel Detection & Location, Radiation Monitoring and Post-Accident Monitoring. High temperature fission chambers are provided at in-vessel locations for monitoring neutron flux. Failed fuel detection and location is by monitoring the cover gas for fission gases and primary sodium for delayed neutrons. Signals of the core monitoring detectors are used to initiate SCRAM to protect the reactor from various postulated initiating events. Radiation levels in all potentially radioactive areas are monitored to act as an early warning system to keep the release of radioactivity to the environment and exposure to personnel well below the permissible limits. Fission Chambers and Gamma Ionisation Chambers are located in the reactor vault concrete for monitoring the neutron flux and gamma radiation levels during and after an accident.

Download Full-text

Neutron Flux Monitoring Based on Blind Source Separation Algorithms in Moroccan TRIGA MARK II Reactor

Science and Technology of Nuclear Installations ◽

10.1155/2017/5369614 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Hanane Arahmane ◽

El-Mehdi Hamzaoui ◽

Rajaa Cherkaoui El Moursli

Keyword(s):

Data Processing ◽

Neutron Flux ◽

Blind Source Separation ◽

Source Separation ◽

Research Work ◽

Nonnegative Matrix ◽

Fission Chamber ◽

Flux Monitoring ◽

Scientific Fields ◽

Material Irradiation

We present an overview of fission chamber’s functioning modes, theoretical aspects of the nonnegative matrix factorization methods, and the opportunities that offer neutron data processing in order to achieve neutron flux monitoring tasks. Indeed, it is a part of research project that aimed at applying Blind Source Separation methods for in-core and ex-core neutron flux monitoring while analyzing the outputs of fission chamber. The latter could be used as a key issue for control, fuel management, safety concerns, and material irradiation experiments. The Blind Source Separation methods had been used in many scientific fields such as biomedical engineering and telecommunications. Recently, they were used for gamma spectrometry data processing. The originality of this research work is to apply these powerful methods to process the fission chamber output signals. We illustrated the effectiveness of this tool using simulated fission chamber signals.

Download Full-text

A Hemispherical Fission Chamber for the Neutron-Flux Monitoring

Instruments and Experimental Techniques ◽

10.1023/b:inet.0000017247.35314.71 ◽

2004 ◽

Vol 47 (1) ◽

pp. 36-38

Author(s):

S. S. Parzhitskii ◽

A. P. Kobzev ◽

Yu. P. Popov ◽

N. A. Gundorin ◽

I. A. Oprya ◽

...

Keyword(s):

Neutron Flux ◽

Fission Chamber ◽

Flux Monitoring

Download Full-text

Design of Neutron Flux Monitoring System for sodium cooled fast reactors

2013 3rd International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications (ANIMMA) ◽

10.1109/animma.2013.6727879 ◽

2013 ◽

Cited By ~ 1

Author(s):

C. P. Nagaraj ◽

M. Sivaramakrishna ◽

K. Madhusoodanan ◽

P. Chellapandi

Keyword(s):

Neutron Flux ◽

Monitoring System ◽

Fast Reactors ◽

Flux Monitoring

Download Full-text

Neutron flux monitoring with in-vessel fission chambers to detect an inadvertent control rod withdrawal in a sodium-cooled fast reactor

Annals of Nuclear Energy ◽

10.1016/j.anucene.2016.04.019 ◽

2016 ◽

Vol 94 ◽

pp. 487-493 ◽

Cited By ~ 2

Author(s):

V. Verma ◽

P. Filliatre ◽

C. Hellesen ◽

S. Jacobsson Svärd ◽

C. Jammes

Keyword(s):

Neutron Flux ◽

Fast Reactor ◽

Control Rod ◽

Flux Monitoring ◽

Fission Chambers

Download Full-text

Neutron Flux Measurements for the PBMR DPP

Fourth International Topical Meeting on High Temperature Reactor Technology, Volume 1 ◽

10.1115/htr2008-58093 ◽

2008 ◽

Author(s):

Gordon Procter ◽

Clark J. Artaud

Keyword(s):

Signal Processing ◽

Low Power ◽

Neutron Flux ◽

Core Region ◽

The Core ◽

Flux Measurements ◽

Flux Monitoring ◽

Power Operation ◽

Nuclear Instrumentation ◽

Fission Chambers

For the Pebble Bed Modular Reactor (PBMR) Demonstration Power Plant (DPP) several neutron flux measurements are made, both within the Reactor Pressure Vessel (RPV) and outside the RPV. The measurements within the RPV are performed by the Core Structures Instrumentation (CSI) system. While those outside the RPV are performed by the Nuclear Instrumentation System (NIS). The PBMR has a long annular core with a relative low power density, requiring flux monitoring over the full 11 M of the active core region. The core structures instrumentation measures the neutron flux in the graphite reflector. Two measurement techniques are used; Fission Chamber based channels with high sensitivity for initial fuel load and low power testing and SPND channels for measurements at full and near full power operation. The CSI flux monitoring supports data acquisition for design Verification and Validation (V&V), and the data will also be used for the characterization of the NIS for normal reactor start-ups and low power operation. The CSI flux measurement channels are only required for the first few years of operation; the sensors are not replaceable. The Nuclear Instrumentation System is an ex core system that includes the Post Event Instrumentation. Due to the long length of the PBMR core, the flux is measured at several axial positions. This is a fission chamber based system; full advantage is taken of all the operating modes for fission chambers (pulse counting, mean square voltage (MSV), and linear current). The CSI flux monitoring channels have many technical and integration challenges. The environment where the sensors and their associated signal cables are required to operate is extremely harsh; temperature and radiation levels are very high. The selection and protection of the fission chambers warranted special attention. The selection criteria for sensors and cables takes cognizance of the fact that the assemblies are built in during the assembly of the reactor internal structures, and that they are not replaceable. This paper describes the challenges in the development of the monitoring systems for the measurement of neutron flux both within the RPV and the ex core region. The selection of detector configuration and the associated signal processing will be discussed. The use of only analogue signal processing techniques will also be elaborated on.

Download Full-text