The security, safety, and economics of MOX fuel use have long been questioned by many experts in France. In November 1990, when the decision was made to build the Melox plant, Jean-Paul Schapira, a well-known nuclear physicist questioned the value of MOX use in the journal La Recherche.1 Recently, in the Gazette Nucléaire, Monique Sené of the GSIEN (Association of Scientists for Nuclear Energy Information), shows that the objections raised by J.P. Schapira have been borne out by the MOX fuel assemblies that have been used by EDF.2

Schapira and Sené identify a number of safety problems posed by MOX compared to traditional uranium fuel which it replaces: more delicate fabrication of fuel rods to protect against contamination, greater risk of loss of control during reactor operation despite the presence of extra control rods, release of fission gases, corrosion of fuel rods during reactor operation. Given the signs of aging which are now appearing in the French 900 MW reactors, these complications are all the more problematic.