Speaker
Description
Most nuclear reactor developments rely on evaluated databases for numerical simulations to optimize and predict performance and reactor control parameters. However, these databases still present large uncertainties, preventing calculations from reaching the required precision. An improvement of evaluated databases requires new measurements and better theoretical descriptions of involved reactions. Among the reactions of interest, inelastic neutron scattering (or (n, xn)) are of great importance for the operation of a reactor as they modify the neutron spectrum, the neutron population, and produce radioactive species.
The CNRS-IPHC group is running an experimental program with the GRAPhEME setup installed at the neutron beam facility EC/JRC-GELINA (Geel, Belgium) to measure (n, xn gamma) reaction cross-sections using prompt gamma-ray spectroscopy and neutron energy determination by time-of-flight [1-3]. The obtained exclusive experimental data provide strong constraints on nuclear reaction mechanisms models. A measurement of (n, xn gamma) cross-section have been performed for 183W, which will be discussed in this contribution, in addition to numerous isotopes such as 232Th, 235,238U, natZr and 182,184,186W.
Tungsten is not an active element in nuclear reactors, but, because of its chemical and mechanical properties, it is used in many alloys. The interaction of neutrons with tungsten is therefore of importance for reactor physics, in particular for fusion reactors, in which tungsten is one of the most exposed material to high energy neutrons. From a theoretical point of view, a better description of (n, xn) reactions on tungsten nuclei allows an improvement of models for other key nuclei in reactors fuel. Indeed, tungsten isotopes are deformed like actinides, but also easier to describe as they do not present a neutron-induced fission channel. Still, there are very few measurements available today to test evaluations [4]. Our new experimental data will provide an extensive and constraining test to the predictability of models.
The experimental setup and the data analysis method will be presented. The preliminary experimental results for the 183W isotope will be compared to predictions from the usual nuclear reaction codes.
- [1] “What can we learn from (n, x n γ) cross sections about reaction mechanism and nuclear structure ?”, by Kerveno, Maëlle and Dupuis, Marc and Borcea, Catalin and Boromiza, Marian and Capote, Roberto and Dessagne, Philippe and Henning, Greg andHilaire, Stéphane and Kawano, Toshihiko and Negret, Alexandra and Nyman, Markus and Olacel, Adina and Party, Eliot and Plompen, Arjan and Romain, Pascal and Sin, Mihaela. ND 2019 : International Conference on Nuclear Data for Science and Technology (2019). 10.1051/epjconf/202023901023 https://hal.archives-ouvertes.fr/hal-02957494
- [2] “How to produce accurate inelastic cross sections from an indirect measurement method ?”, by Kerveno, Maëlle and Henning, Greg and Borcea, Catalin and Dessagne, Philippe and Dupuis, Marc and Hilaire, Stéphane and Negret, Alexandru and Nyman, Markus and Olacel, Adina and Party, Eliot and Plompen, Arjan in EPJ N - Nuclear Sciences & Technologies 4, (2018). 10.1051/epjn/2018020 https://hal.archives-ouvertes.fr/hal-02109918
- [3] “From γ emissions to (n,xn) cross sections of interest : The role of GAINS and GRAPhEME in nuclear reaction modeling”, by Kerveno, M. and Bacquias, A. and Borcea, C. and Dessagne, Ph. and Henning, G. and Mihailescu, C. and Negret, A. and Nyman, M. and Olacel, A. and Plompen, M. and Rouki, C. and Rudolf, G. and Thiry, C. in European Physical Journal A 51, 12 (2015). 10.1140/epja/i2015-15167-y https://hal.archives-ouvertes.fr/hal-02154831
- [4] Experimental Nuclear Reaction Data (EXFOR) https://www-nds.iaea.org/exfor/