Influences of Am and Np on oxygen potentials of MOX fuels

Oxygen potentials of (Am0.024Pu0.311U0.665)O2−x and (Am0.01Np0.12Pu0.29U0.58)O2−x in the near-stoichiometric region were measured at 1473, 1573 and 1623 K by thermogravimetry and the influences of Am and Np on the MOX fuels were evaluated. The measurements were carried out by a gas equilibrium method using an (Ar, H2,H2O) gas mixture. Oxygen potentials of (Am0.024Pu0.311U0.665)O2−x were slightly higher than those of (Pu0.3U0.7)O2−x while those of (Am0.01Np0.12Pu0.29U0.58)O2−x and (Pu0.3U0.7)O2−x were almost the same. It was concluded that oxygen potentials of MOX fuels were slightly increased by a small amount of Am and not affected by Np. ► Oxygen potentials of Am and Np-containing MOX were measured. ► The measurements were done in a region of near-stoichiometry. ► Oxygen potentials of MOX were slightly increased by the small amount of Am. ► Oxygen potentials of MOX were not influenced by Np addition.