The first measurements of the response of diamond detectors to neutrons in the energy range 17–34 MeV are presented. The diamond detectors were irradiated with quasi-monoenergetic neutrons generated ...through the 7Li(p,n)7Be reaction. The measured pulse-height spectra show specific peaks associated to neutron induced reactions in carbon. The peak of the 12C(n,α0)9Be was clearly separated from the rest of the spectra. The12C(n,d0)11B and 12C(n,p0)12B peaks were clearly identified on a continuum originating from the breakup12C(n,3α) reaction, which dominates the low-energy part of the pulse-height spectra. The 12C(n, α0)9Be, 12C(n,d0)11B and 12C(n,p0)12B cross sections that have never been measured in this high-energy range before were determined. The measured data are compared with the European Activation File EAF-2010 library evaluated values.
•Diamond detector response to neutrons with energies above 20 MeV.•Neutron cross sections for the reactions12C(n,α0)9Be,12C(n,d0)11B and12C(n,p0)12B above 20 MeV.•Quasi-monoenergetic neutrons.
The MSM method is an experimental technique for determination of reactivity of a sub-critical reactor. It consists of one dynamic measurement followed by two static measurements, which use an ...extraneous neutron source. For the data analysis, the core averaged kinetic parameters need to be calculated as well as a spatially-dependent correction factor that corrects for the point kinetics approximation. In order to test the range for which the method is valid and to demonstrate the reliability of the correction factor calculations in a fast reactor, a dedicated experimental campaign was performed in the fast lead-bismuth VENUS-F reactor. The reactivity of a dozen of sub-critical configurations was measured with the MSM method using ten
235
U fission chambers. The detectors were located at various distances from the active zone and from the extraneous neutron source, leading to a large range of values of a correction factor (calculated with the Monte Carlo MCNP5 code) used in the data analysis.
•Massimo Salvatores was the key persons in the promotion of integral experiments.•He initiated many international programs of integral experiments in the world.•He expressed a great interest to the ...integral experiments in the VENUS-F facility.•VENUS-F experiments to support ADS MYRRHA and LFR core designs are presented.
In spite of the remarkable progress of computational tools in the last decades, integral experiments in zero-power facilities are still of a great importance in the world for nuclear data validation, licensing of new core designs and education and training. Massimo Salvatores was one of the key persons in the promotion of integral experiments and their analysis since the early 1980s. He initiated many international programs of integral experiments in different zero-power facilities in the world. He expressed a great interest to the integral experiments in the VENUS-F facility that have been performed since 2011 to support ADS MYRRHA and LFR core designs. Some of these experiments and associated calculations are presented in this paper.
Nuclear instrumentation in VENUS-F Wagemans, J.; Borms, L.; Kochetkov, A. ...
EPJ Web of Conferences,
01/2018, Letnik:
170
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
VENUS-F is a fast zero power reactor with 30 wt% U fuel and Pb/Bi as a coolant simulator. Depending on the experimental configuration, various neutron spectra (fast, epithermal, and thermal islands) ...are present. This paper gives a review of the nuclear instrumentation that is applied for reactor control and in a large variety of physics experiments. Activation foils and fission chambers are used to measure spatial neutron flux profiles, spectrum indices, reactivity effects (with positive period and compensation method or the MSM method) and kinetic parameters (with the Rossi-alpha method). Fission chamber calibrations are performed in the standard irradiation fields of the BR1 reactor (prompt fission neutron spectrum and Maxwellian thermal neutron spectrum).
The Source Jerk Integral (SJI) method has been extensively used to determine the subcriticality in VENUS-F zero-power experiments since 2012. The obtained results were in the range from −5 $ to about ...−20 $ and concerned the subcriticalities of accelerator-driven system MYRRHA mockup cores. Within the SALMON program, which is dedicated to the safe loading procedure of pressurized power reactors, five subcritical core configurations were assembled and studied in the VENUS-F reactor in 2019. These cores simulated the loading process in inverse mode: from more reactive to deep subcritical. The subcriticality of five variants of the SC11 VENUS-F core was changed in steps from −20 $ to about −100 $ by replacing the fuel assemblies with lead reflector assemblies. The subcriticality levels were determined with the pulsed neutron source (PNS) and SJI methods. The GENEPI-3C deuterium accelerator coupled with VENUS-F was used as an external neutron source. The results of the measurements obtained with the SJI method are presented in this paper. Time-dependent Monte Carlo calculations were performed to simulate the SJI experiments and to determine spatial-energy correction factors. Static Monte Carlo simulations were performed to calculate neutron spectra and reactivity. The results of the measurements (both SJI and PNS) are compared with the static MCNP calculations.
The article summarizes series of experiments devoted to studies of (n,xn) cross-sections by the activation method and states numerical values of measured cross-sections. The activation samples are ...used to measure neutron flux produced during accelerator driven system studies. The threshold (n,xn) reactions are used but experimental cross-section data of such reactions are mostly not available for neutron energies above 30MeV. We focused for this reason on activation materials (Al, Au, Bi, In Ta, and Y) commonly used for such purposes and we also measured other materials (Cu, Fe, I, Mg, Ni, and Zn). The cross-sections were studied using quasi mono-energetic neutron sources based on proton reactions in a 7Li target in the energy range from 17MeV up to 94MeV. We observed a good agreement of the obtained data with the experimental data in the EXFOR database and also with the calculations performed using the code TALYS 1.4. Many of presented measurements represent the first ever measurement for a given reaction at a given neutron energy.
•The cross-sections were studied in the energy range from 17MeV up to 94MeV.•Results are compared with TALYS code, EXFOR database and with the library IRDFF.•Many of presented measurements represent the first ever measurement.
The potential use of a pulsed neutron source (PNS) to measure reactivity during nuclear fuel loading as a means to prevent core loading errors has been studied at the GUINEVERE facility. This ...facility couples the deuteron accelerator GENEPI-3C to the fast neutron subcritical reactor VENUS-F at the Belgian Nuclear Research Center SCK·CEN. The 14-MeV neutrons are produced in the reactor core center via
fusion reactions. PNS experiments were performed in five reactor configurations corresponding to the different loading steps of VENUS-F. The evolution of the neutron flux during these PNS experiments was measured by several
235
U fission chambers in various positions in the inner and outer reflector and analyzed using the area-ratio method. The results show that, despite strong spatial effects, a strong correlation between the reactivity values given by the area-ratio method and some reference reactivity values remains throughout the reactor unloading. Monte Carlo simulations were first validated by comparison with the data and then used to investigate the sensitivity of the method to a core loading error. First results show that some loading errors could be experimentally detected using a PNS.
The Modified Source Multiplication method is used to determine an unknown reactivity level of a reactor from a known one if one has access to the detector counting for both levels when the reactor is ...fed by a constant neutron source like an Am-Be source. When available, an accelerator driven source, in continuous mode, can be useful as its intensity can be tunable and then adapted to the experimental conditions. However, in that case, the MSM technique must be extended to account for an external source whose intensity, energy and angular distributions can vary from one measurement to another. In this paper, this Modified Multi-Source Multiplication (MMSM) method is applied to measurements done during the FREYA project in the GUINEVERE facility, operated with the GENEPI-3C accelerator providing a mixture of (D,T) and (D,D) neutrons. The monitoring of these sources through the detection of the associated charged particles allows the calculation of the MMSM factors and the estimate of the reactivity values. The results are compared in different configurations with the reactivity obtained with an Am-Be source or in dynamic measurements performed with GENEPI-3C. Their excellent agreement shows the possibility of using such accelerator-based neutron sources for MSM measurements when they are correctly monitored. This is of great interest for deep sub-critical level characterization for which detector count rates per source neutrons might be low.
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