Prompt reactivity determination in a subcritical assembly through the response to a Dirac pulse

F. Perdu (1) , J.M. Loiseaux (1) , A. Billebaud (1) , R. Brissot (1) , D. Heuer (1) , C. Le Brun (1) , E. Liatard (1) , O. Meplan (1) , E. Merle (1) , H. Nifenecker (1) , J. Vollaire (1)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie

The full understanding of the kinetics of a subcritical assembly is a key issue for its online reactivity control. Point kinetics is not sufficient to determine the prompt reactivity of a subcritical assembly through the response to a dirac pulse, in particular in the cases of a large reflector, a small reactor, or a large subcriticality. Taking into account the distribution of intergeneration times, which appears as a robust characteristic of each type of reactor, helps to understand this behaviour. Eventually, a method is proposed for the determination of the prompt reactivity. It provides a decrease rate function depending on the prompt multiplication coefficient Keffp. Fitting a measured decrease rate with this function, calculated once for the reactor, gives the true value of keffp. The robustness of the method is tested. (Elsevier)

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

F. Perdu, J.M. Loiseaux, A. Billebaud, R. Brissot, D. Heuer, et al.. Prompt reactivity determination in a subcritical assembly through the response to a Dirac pulse. Progress in Nuclear Energy, 2003, 42, pp.107-120. ⟨10.1016/S0149-1970(02)00101-4⟩. ⟨in2p3-00012235⟩