Control of Nuclear material hold-up in MOX Fuel Fabrication plants in Europe

MOX fuel has been fabricated in Europe for over 30 years and marries well-established fuel fabrication processes with mature plutonium management techniques. By the Millennium around half a million mixed oxide fuel rods will have been made for thermal reactor fuel corresponding to more than 1000 tHM. The combined capacity of the current MOX fuel fabrication plants in Europe is over 250tHM/yr, all of which is subject without discrimination to Euratom Safeguards. These plants will normally contain large quantities of plutonium, mostly in stores but also in the process lines. While some protagonists of the nuclear industry suggest that MOX plants are awash with nuclear material which cannot be adequately safeguarded and that material ‘stuck in the plant’ could conceal clandestine diversion of plutonium, the real situation in Europe is very different : nuclear operators have gone to considerable efforts to deploy effective systems for safety, security and nuclear material control and accountancy, and the safeguards authorities likewise have implemented a hierarchy of safeguards measures enabling them to give safeguards assurances for MOX plants. This paper is focusing on the issue of hold -up : it presents a definition of \"hold-up\" and \"residual inventory\" and it describes how work-in progress and in particular material hold -up are controlled, measured and accounted for, taking full account of the accumulated experience in European MOX fabrication facilities.