During the fabrication of mixed oxide (MOX) fuel elements at 5% plutonium oxide enrichment a rod was detached from the insertion device and was therefore incompletely inserted in the squeleton. During the next operations, the rod was broken by mechanical interaction with a tool. The workshop was contaminated by plutonium oxide. Eight workers were slightly contaminated externally; one of them was contaminated internally but at a level less than the limit. As the scale extension for non reactor is no yet implemented, no official rating is available. An officious rating at level 2 was approved by the Belgian Authority, under defense in depth. This is based on IV.18.104.22.168 (MOX fuel) taking account of the loss of one important barrier. No additional factor has to be applied.