21-29 July 2022
US/Pacific timezone

Time-of-flight measurements of MINERVE samples containing fission products and neutron absorbing isotopes

26 Jul 2022, 11:39
Folsom ()



Gilles Noguere


The zero-power reactor MINERVE (CEA Cadarache) was designed to perform reactivity worth measurements by the oscillation technique. The various experimental programs, undertaken for the last thirty years, involved cylindrical samples with a diameter of about 1 cm and a height ranging from a few cm to 10 cm. Most of the samples are composed of UO2 pellets with a given fission product, actinide or neutron absorbing isotope in a double-sealed Zry-4 container.

An experimental program started in 2015 in collaboration with the Joint Research Centre of Geel to study the MINERVE samples at the time-of-flight facility GELINA by the neutron transmission technique. The two main objectives consist of checking both the composition of the MINERVE samples provided by the manufacturer and the quality of the resonance parameters recommended in the evaluated neutron data library JEFF-3.3 [1]. The pioneer experiments on MINERVE samples containing 107Ag and 109Ag revealed a substantial Tungsten contamination that was not reported by the manufacturer [2]. Such a Tungsten contamination is related to the manufacturing process of the sample pellets by powder compacting. The observed Tungsten contaminations lead to non-negligible increases of the C/E ratios up to a few percent. A second experimental campaign on MINERVE samples containing 99Tc provided useful insight on the quality of the 99Tc resonance parameters measured at the GELINA facility at the end of the 90s [3].

The ongoing program continuing through 2022 will deliver data for samarium (natural, 147, 149, 152), neodymium (natural,143,145), gadolinium (natural, 155), europium (151, 153), rhodium (103), Cesium (133), hafnium (180), dysprosium (160, 161, 162, 163, 164) and erbium (168, 170). The present work will focus on the data analysis technique developed for long cylindrical samples with a diameter smaller than the neutron beam, and on the grain size distribution model implemented in the resonance shape analysis REFIT and CONRAD.

[1] A. J. M. Plompen et al, The joint evaluated fission and fusion nuclear data library JEFF-3.3, Eur. Phys. J. A (2020) 56:181
[2] L. Salamon et al., Neutron resonance transmission analysis of cylindrical samples used for reactivity worth measurements, J. Radioanal Nucl. Chem. https://doi.org/10.1007/s10967-019-06611-9 (2019)
[3] G. Noguere et al., Average neutron cross sections of Tc, Phys. Rev. C 102, 015807 (2020)

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