  A transversal mapping of the Gd concentration was measured in UO2-Gd2O3
nuclear fuel pellets by electron paramagnetic resonance spectroscopy (EPR). The
quantification was made from the comparison with a Gd2O3 reference sample. The
nominal concentration in the pellets is UO2: 7.5 % Gd2O3. A concentration
gradient was found, which indicates that the Gd2O3 amount diminishes towards
the edges of the pellets. The concentration varies from (9.3 +/- 0.5)% in the
center to (5.8 +/- 0.3)% in one of the edges. The method was found to be
particularly suitable for the precise mapping of the distribution of Gd3+ ions
in the UO2 matrix.
