Accounting for spatial effects in measuring reactivity using the inverse solution of the kinetic equations

Determination of the Reactivity of a Reactor Upon Insertion of Absorbing Rods

“…The suggestions to use in one form or another computational modeling of the core to eliminate the infl uence of the spatial effect are contained in [4,7,9]. The determinations of the reactivity which were obtained in the case where these suggestions were used, strictly speaking, can no longer be regarded as experimental.…”

“…A spatial effect of reactivity is observed: the reactivity calculated from a detector signal depends on the mutual arrangement of the detector and the moved working organ as well as on the velocity of the detector and the time when motion ceases. The problem of the spatial effect of reactivity has been a subject of discussion for many years [4][5][6].When the control organ stops moving under conditions where feedback can be neglected, as the neutron distribution corresponding to the change in the state of the core is established, the error owing to the spatial effect asymptotically goes to zero [7]. However, the possibility of measuring a detector signal and therefore calculating the reactivity is lost in a subcritical state of the reactor because as a rule the integral neutron fl ux decreases long before a new stationary distribution is established.…”

“…A spatial effect of reactivity is observed: the reactivity calculated from a detector signal depends on the mutual arrangement of the detector and the moved working organ as well as on the velocity of the detector and the time when motion ceases. The problem of the spatial effect of reactivity has been a subject of discussion for many years [4][5][6].…”

Some Inverse Problems for Reactor Point Kinetics

“…Among them there are methods that require knowledge of all other coefficients of nuclear reactor point kinetics equations (Usachoff, 1955;Henry, 1958;Keepin, 1965;Bell and Glasstone, 1970;Shikhov, 1973;Mogilner et al, 1974;Usachoff and Bobkov, 1980;Kazanski et al, 1981;Kazansky and Matusevich, 1984) and methods requiring knowledge of only some of these coefficients (Mogilner et al, 1974;Kazanski et al, 1981). In particular, methods of simultaneous and consistent determination of reactivity ρ and q value of an external neutron source is described in (Mogilner et al, 1974).…”

“…In particular, methods of simultaneous and consistent determination of reactivity ρ and q value of an external neutron source is described in (Mogilner et al, 1974). Generalization of this method with the purpose of taking into account spatial effects of reactivity is presented in (Kazanski et al, 1981), etc. These well-established methods are widely used in a practice of reactor's measurements.…”