Two methods are presented for optimally calculating spatial distributi
ons of neutron flux in a nuclear reactor core. Both techniques, Kalman
filtering and maximum likelihood estimation, simultaneously account f
or all initial information contained in the nominal core specification
s and in-core measurements, as well as all of the uncertainties within
the system, to provide a minimum variance estimate of neutron flux. T
hese methods resolve discrepancies in the initial information in a sta
tistically optimal manner, thereby providing valuable insight into the
nature of the optimal solution obtained. Despite radically different
algorithms, both methods yield the same minimum variance estimate for
the quantity of interest. The algorithms have been successfully tested
for one-dimensional axial and two-dimensional x-y flux mapping proble
ms with simulated in-core data sets.