2 research outputs found
Two-point theory for the differential self-interrogation Feynman-alpha method
A Feynman-alpha formula has been derived in a two region domain pertaining
the stochastic differential self-interrogation (DDSI) method and the
differential die-away method (DDAA). Monte Carlo simulations have been used to
assess the applicability of the variance to mean through determination of the
physical reaction intensities of the physical processes in the two domains.
More specifically, the branching processes of the neutrons in the two regions
are described by the Chapman - Kolmogorov equation, including all reaction
intensities for the various processes, that is used to derive a variance to
mean relation for the process. The applicability of the Feynman-alpha or
variance to mean formulae are assessed in DDSI and DDAA of spent fuel
configurations.Comment: 15 pages, 5 figures. Submitted to EPJ Plu
A new method for absolute measurement of βeff based on Microscopic Noise Experiments and the Two-Region model in the IPEN/MB-01 research reactor
A new method for absolute measurement of the effective delayed neutron fraction, βeff, based on Microscopic Noise Experiments and the Two-Region Model was developed at the IPEN/MB-01 Research Reactor. In contrast with other techniques, the main advantage of this new methodology is to obtain the parameters in a purely experimental way, eliminating all parameters that are difficult to measure or calculate. Consequently, the uncertainties associated to these parameters are eliminated and the accuracy in βeff is improved. Experimentally, several Rossi-α and Feynman-α measurements were performed in the IPEN/MB-01 in a large subcritical interval. By adopting the present approach, the final results show that uncertainties of 0.67% and 0.97% on, respectively, βeff and Λ are achievable. The theory/experiment comparison of βeff shows that among the available nuclear data libraries JENDL3.3 has the best performance