Speaker
Description
Caesium-133 is an important fission product for burnup credit as it plays a role in the transmutation of $^{135}$Cs. Neutron-induced cross sections in $^{133}$Cs have been investigated in reference [1]. There are no capture cross section data available in EXFOR describing the resonances in the Resolved Resonance Region. As $^{133}$Cs has a high capture cross section, an accurate measurement of the $^{133}$Cs(n,γ) cross section is needed for precise calculations. CEA reactivity worth calculations in the Minerve experimental reactor showed that the capture cross section in the JEFF evaluation overestimates measured capture rates by 5.5% with 1.5% uncertainty. The burnup credit model is sensitive to the $^{133}$Cs capture cross section from thermal up to 1 keV, therefore cross section data in this energy region would be most important for burnup credit analysis. Also, the latest evaluated data files do not provide cross section covariance information for $^{133}$Cs; new data providing cross section covariance information, would benefit burnup credit analysis by enabling the propagation of cross section uncertainties to calculated keff values. In response to all these needs, a new measurement of the $^{133}$Cs(n,γ) cross section was proposed at the Los Alamos Neutron Science Center (LANSCE) in the scope of the Nuclear Criticality Safety Program (NCSP). The $^{133}$Cs(n,γ) reaction was measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at the thermal and resonance regions, taking advantage of the new Mark-IV spallation target recently installed at LANSCE, that increases the neutron flux in the keV region [2]. The experiment and preliminary results are here presented.
[1] L. C. Leal et al., Assessment of Fission Product Cross-Section Data for Burnup Credit Applications,ORNL/TM-2005/65 (2007).
[2] E. Leal-Cidoncha et al., Neutron flux in flight path 14, LA-UR-24-23224 (2024).
| Session | Decay Data and Delayed Neutrons |
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