Page name: ARRSProjekti / 2020 / Referenčni eksperiment za validacijo modeliranja odziva jedrske instrumentacije na nevtrone in žarke gama

Referenčni eksperiment za validacijo modeliranja odziva jedrske instrumentacije na nevtrone in žarke gama

Nazaj na seznam za leto 2020

Oznaka in naziv projekta

NC-0015 Referenčni eksperiment za validacijo modeliranja odziva jedrske instrumentacije na nevtrone in žarke gama
NC-0015 Experimental Benchmark for validation of the modelling of neutron and gamma instrumentation

Logotipi ARRS in drugih sofinancerjev

© Javna agencija za raziskovalno dejavnost Republike Slovenije

Projektna skupina

Vodja projekta: dr. Vladimir Radulović

Vsebinski opis projekta

  • Experimental Benchmark for validation of the modelling of neutron and gamma instrumentation


  • In Material Testing Reactors (MTR) as well as in fusion facilities and GEN-IV type reactors, neutron flux measurements are always performed in a g and neutron mixed field usually of the same order of magnitude. Thus, g flux contribution has to be taken into account in the neutron sensor design or in measurement methods for minimizing their impact or correcting it. The evaluation of this contribution can become an issue for neutron measurement in perturbed areas where the ratio of the two kind of particle flux is strongly variating in time or in space such as in the transition zone between the core and the reflector or in some low power reactor dynamic states. With the constant improvement of the computational modelling codes, an accurate and reliable evaluation of the g contribution is mandatory to reach the minimum uncertainty level required for comparison with simulations. The collaboration on nuclear instrumentation started in 2008 between the CEA Experimental Physics Service (Experimental physics, Safety experiment and Instrumentation Section since January 2018) and the Reactor Physics Division of the Jozef Stefan Institute (JSI) in the frame of bilateral agreement between the CEA and the Slovenian Ministry of Higher Education, Science and Technology. Since the first two years’ collaboration focused on reactor dosimetry, more than 10 development projects have been successfully achieved on several subjects: miniature fission chambers, Self-Powered Neutron Detector and gamma (ionization chambers and thermoluminescent Detectors) measurement techniques, calorimetry measurements as well as kinetic parameter measurement techniques (beff), reactor dosimetry unfolding techniques and nuclear data improvements [3]. Considering the influence of the g flux in the neutron flux measurements techniques highlighted above, a generic study has been started few years ago for developing sensors and associated modelling schemes to better characterize the g flux. Firstly, experimental measurements have been started by CEA in OSIRIS reactor with ionisation chambers [4]. Then the study has been pursued in the Slovenian TRIGA reactor in collaboration with JSI teams with, in particular, experimental campaigns using ionisation and fission chambers sensors ([5] to [7]). On the modelling side, TRIPOLI 4 and MNCP based calculation schemes have been upgraded for taking into account neutrons and g (prompt and delayed) leading to good agreements between calculations results and measurements ([8] to [9]) as shown in figure 1 for fission chamber measurements. Work is ongoing with calorimetry measurement of nuclear heating. Considering SPND sensors, the MATISSe toolbox [10], based on a multistep Monte Carlo calculation model, has been developed by CEA for modelling both neutron and  SPND responses. The SPNDs and its immediate environment are finely modelled (geometry and material composition). The SPND response is predicted thorough calculations of neutron and g partial detector sensitivities, using calculated neutron and g fields (levels and spectra). Calculations to measurements comparisons obtained in different MTRs are quite satisfying for Rh SPND as shown in Table 1 [11]. One also notes that nuclear data library for g and charged particles has also been upgraded recently [12].

    Project objectives:

    Specific Objective 1: Fine characterization of a benchmark irradiation location. The JSI team, through a detailed and validated computational model of the JSI TRIGA reactor and of the selected irradiation location, will accomplish this phase. This will be done using the most recent version of the MCNP code. This calculation scheme has been in constantly used during last two decades at the Reactor Physics Department. It has also been verified and widely validated for calculations of the reactor. In addition, an experimental campaign (mainly with dosimetry techniques) will be performed in the irradiation location selected for the benchmark. Dosimetry measurements will be done at the JSI facility except if some specific radio-isotope measurements or cross-check measurements appear to necessarily be done at the MADERE CEA facility, and also if the radionuclides half-lives allow it. The main outputs of this phase will be a validated set of neutron and gamma data (spectra, reaction rates…) in the unperturbed benchmark irradiation location, so called reference situation.

    Specific Objective 2: Experimental measurements benchmark The Specific Objective 2 of the research project comprises the following joined CEA-JSI actions: - The preparation of the sensors (documentation for modelling, calibration) and of the irradiation device by both CEA and JSI teams depending on the type of the sensors tested. - The organization and the performing of the Benchmark experimental campaign in the JSI TRIGA reactor. Dosimetry measurements will be done at the JSI facility except if some specific radio-isotope measurements or cross-check measurements appear to be necessary to be done at the MADERE CEA facility. - The first level analysis (homogeneity, uncertainties...) of the measured results given by the different sensors. - The Calculation to Measurement comparison analysis based on the JSI reference detailed scheme

    Specific Objective 3: Comparison of the CEA and JSI neutron and gamma calculation schemes for instrumentation applications. In addition to the experimental campaign, CEA will setup a TRIPOLI 4 modelling scheme of the TRIGA reactor based on the information available in the IRPHE and ICSBEP benchmarks (simplified geometry) in order to be able to perform sensor modelling. An evaluation of the Uncertainty budget will also be proposed for each kind of instrumentation. The CEA will apply this instrumentation calculation scheme (TRIPOLI 4 – JEFF3 – IRDFF-II) taking into account the geometry of the sensors and of the irradiation device and the actual information about the irradiation campaign. These results will be compared to the JSI ones obtained with the MCNP-ENDF/BVII – IRDFF calculation scheme.

    • Project outcomes

    The main project outcome is a unique experimental benchmark values (M with C/M analysis, uncertainty budget…) for the main neutron and gamma sensor types such as Fission chambers, self-powered neutron detector, ionisation chamber, dosimeter. Secondly, based on the comparison of the results obtained by the two neutron and gamma modelling schemes developed by CEA and JSI, recommendations for modelling and analysis of instrumentation operating in mixed gamma-neutron fields will be proposed. These outcomes have applications in the neutron and gamma measurements for reactor applications, such as Nuclear Power Plants (NPP), Material Testing Reactors( MTR) and GEN-IV type reactor operating instrumentation, instrumentation for experiments in MTR and Zero Power Reactors (ZPR) and also for fusion applications like measurement of the neutron an gamma flux in the peripherical structures (Blanket) of ITER. Beyond scientific publications at international conferences and in SCI journals, results of this project could also be considered as a first step toward the publication of experimental benchmark dedicated to instrumentation modelling through the AEN or IAEA dedicated projects.


    [2] IRPhE database ( [3] C. Destouches, L. Snoj, J.F. Villard, V. Radulovic and al. . “A Review of 10 years of JSI – CEA collaboration on nuclear instrumentation development” Proceedings of NENE 2018 Conference Portoroz – Slovenia [4] D. Fourmentel and al. “Measurement of photon flux with a miniature gas ionization chamber in a Material Testing Reactor” NIM-A724(2013) 76–82 [5] V. Radulovic and al. “Measurements of miniature ionization chamber currents in the JSI TRIGA Mark II reactor demonstrate the importance of the delayed contribution to the photon field in nuclear reactors” NIM-A Vol. 804, 21 Dec. 2015, Pages 149-154 [6] G. Zerovnik and al. “Validation of the neutron and gamma fields in the JSI TRIGA reactor using in-core fission and ionization chambers” Applied Radiation and Isotopes -Volume 96, February 2015, Pages 27-35 [7] G. Žerovnik, T. Kaibaa and al. “Validation of the Neutron and Gamma Flux distributions in the JSI TRIGA Reactor Core” Proceedings of the NENE 2014 conference, Portorož, Slovenia [8] T. Goricanec and al. “Fission rate redistribution experiments at the JSI TRIGA reactor for the validation of computer codes” proceedings of the PHYSOR 2018 conference - Cancun, Mexico [9] K. Ambrožic “Delayed g determination in research reactors by synchronous measurements with fission and ionization chambers” Proceedings of the RRFM/IGORR 2019 Conference March 2019 - Crowne Plaza Dead Sea Resort, Jordany [10] L. Barbot “The Self-Powered Detector Simulation ‘MATiSSe’ Toolbox applied to SPNDs for severe accident monitoring in PWRs” proceedings of ANIMMA 2017 - EPJ Web of Conferences 170, 08001 (2018) [11] L. Barbot and al. “Calculation to Experiment Comparison of SPND Signals in Various Nuclear Reactor Environments”, ANIMMA conference, 2015, Lisbon Portugal

    [12] T. Kawano and al. “IAEA Photonuclear Data Library 2019” to be published in Nuclear Data Sheets – available at (Cornell University)

Osnovni podatki sofinanciranja so dostopni na spletni strani SICRIS.

Faze projekta in opis njihove realizacije

Months 1-6:

- Selection of a location for the Benchmak irradiation

- Monte Carlo calculations of reference (unperturbed) neutron and gamma spectra in the selected location in the JSI TRIGA reactor.

- Definition of the irradiation campaign for calibration of the benchmark location

- Definition of the principle of the irradiation campaign for the experimental benchmark.

- Selection of the sensors to be tested.

- Definition of the irradiation device(s)

Months 7-14:

- Procurement of sensors and dosimeters (calibration included if necessary)

- Execution of experimental measurement campaign for qualification of the Benchmark location in the JSI TRIGA reactor

- Execution of the Benchmark experimental measurement campaign Benchmark in the JSI TRIGA reactor

- Analysis of experimental data to process experimental results (M)

- Development of the CEA neutron and gamma calculation scheme

Months 15-21:

- Modelling of the benchmark experiments (sensors description included) with the CEA and JSI respective modelling schemes to provide calculated results (C).

- Analysis of the results obtained by the CEA and JSI modelling schemes (C/M and C/C).

- Recommendations for instrumentation modelling and analysis for mixed gamma-neutron fields.

Months 22-24

- Submission of the project results for publication (NIM-A, ARI)

- Preparation of the final report

Bibliografske reference

Nazaj na seznam projektov po letih