21-29 July 2022
US/Pacific timezone

Results of the $^{244}$Cm, $^{246}$Cm and $^{248}$Cm neutron-induced capture cross sections measurements at EAR1 and EAR2 of the n_TOF facility

26 Jul 2022, 12:15
Capitol ()



Victor Alcayne the n_TOF Collaboration


V. Alcayne a), A. Kimura b), E. Mendoza a), D. Cano-Ott a), T. Martinez a), E. González-Romero a), A. Pérez de Rada a), and the n_TOF collaboration c)

a) Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), E-28040 Madrid, Spain
b) Japan Atomic Energy Agency (JAEA), Tokai-mura, Japan
c) Conseil Européen pour la Recherche Nucléaire, CERN, Switzerland

The safe and efficient management of the high level waste produced in the operation of nuclear reactors requires more accurate nuclear data. In particular, inventory calculations of the spent nuclear fuel (SNF) and the derived magnitudes such as the decay heat, radio toxicity or neutron and gamma dose, among others, rely on the accuracy of neutron induced reaction cross sections ruling the burn-up in the reactor. The Cm isotopes require a special attention due to their various implications along the fuel cycle. For instance, $^{244}$Cm is responsible of ∼10% of the radio-toxicity and the decay heat in the spent nuclear fuel in a Light Water Reactor (LWR) during the first fifteen years after unloading the SNF from the reactor. Furthermore, the neutron emission in the spent fuel is dominated by the $^{244}$Cm and $^{246}$Cm spontaneous fission during the first 10$^4$ years of disposal. From the point of view of reactor (LWR) and fuel cycle parameters, the sensitivity analyses performed in [1] indicate that uncertainties in the $^{244}$Cm capture cross section need to be reduced to 4.1% between 4 and 22.6 eV and to 14.4% between 22.6 and 454 eV. Last, but not least, a more accurate knowledge of the capture cross sections of $^{244}$Cm, $^{246}$Cm and $^{248}$Cm is required for improving the calculations on the formation of heavier isotopes such as Bk, Cf and other Cm isotopes.

In this work, we will present the final results of the capture cross section measurement on $^{244}$Cm, $^{246}$Cm and $^{248}$Cm performed at the CERN n_TOF facility [2]. It is important to notice that, the Cm samples used in the experiment at n_TOF have been used previously in an experiment at J-PARC [3]. At n_TOF, the capture cross section measurements of $^{244}$Cm, $^{246}$Cm and $^{248}$Cm were performed at the 20 m vertical flight path (EAR2) with three C$_6$D$_6$ total energy detectors [4]. In addition, the cross section of $^{244}$Cm was measured at the 185 m flight path (EAR1) with a Total Absorption Calorimeter (TAC) [5]. The combination of measurements in EAR1 and EAR2 and the use of two complementary experimental techniques, the total absorption calorimetry and the pulse height weighting technique, has contributed to control and reduce the systematic uncertainties in the results.
We will present the radiative kernels of the resonances of $^{244}$Cm, $^{246}$Cm and $^{248}$Cm obtained in the energy ranges from 7 to 300 eV, 4 to 400 eV, and 7 to 100 eV, respectively, and compare the results of the measurement with previous capture and transmission data and evaluated cross sections.

[1] G. Aliberti et. al., , Ann. Nucl. Ener. 33, 700 (2006)
[2] C. Guerrero et al. Eur. Phys. J. A 49, 27 (2013)
[3] A. Kimura et. al., Jour. Nucl. Sc. Tech. 49, 708 (2012)
[4] U. Abbondannoet al., Nuc. Inst. Meth. A. 521, 454-467, (2004)
[5] C.Guerrero et al., Nucl. Instrum. Meth. A 608, 424 (2009)

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