An experimentally measured relationship between flux tilt and excess reactivity

Abstract

The axial flux tilt in the tightly coupled core of the Georgia Tech Research Reator (GTRR) is caused by the partial insertion of controls at one end of the core. It is demonstrated that an index which describes the extent of the flux tilt is directly proportional to the excess reactivity of the core, with the constant of proportionality being the eigenvalue separation of the reactor. Two experiments were devised to test this proportionality, one to measure flux tilt as a function of control insertion, and one to measure excess reactivity as a function of control insertion. Results indicate the excess reactivity can be measured using only the static flux perturbation caused by the controls.