Auto-correlation and variance-to-mean measurements in a subcritical core obeying multiple alpha-modes

作者：Berglof Carl^*; Fernandez Ordonez Manuel; Villamarin David; Becares Vicente; Gonzalez Romero Enrique M; Bournos Victor; Munoz Cobo Jose Luis

来源：Annals of Nuclear Energy, 2011, 38(2-3): 194-202.

DOI：10.1016/j.anucene.2010.11.009

• Neutron noise experiment
• Auto-correlation
• Rossi-alpha
• Variance-to-mean
• Feynman-alpha
• Reactivity determination

Neutron noise measurements based on the Rossi-alpha and Feynman-alpha methodologies have been performed in a heterogeneous subcritical system. It is shown that the traditional single alpha-mode formulations of the Rossi-alpha and Feynman-alpha methods are not applicable due to the presence of higher alpha-modes. Formalisms taking into account multiple alpha-modes are applied resulting in satisfactory results. Three alpha-modes could be identified using the Rossi-alpha method, whereas only two could be obtained using the Feynman-alpha method. In the Feynman-alpha case, the possibility to obtain the fastest decaying alpha-mode was diminished due to detector dead time effects. It was found that the slowest decaying alpha-mode does not exactly correspond to the prompt decay found in pulsed neutron source measurements, which confirms the results of previous studies. Strengths and weaknesses of the multiple alpha-mode Rossi-alpha and Feynman-alpha methods observed in this study are pointed out.

• 出版日期2011-3