Fabrication of simulated intermediate-burnup ACR fuel in the RFFL

Due to the differences in reactor design between the Advanced CANDU Reactor (ACR®) and a standard CANDU® reactor, a program of reactor physics validation measurements is being conducted in the ZED-2 reactor to support the use of the reactor physics computer code tool set for application in ACR. These measurements include a series of experiments using MOX fuel that simulated intermediate-burnup ACR fuel. The Recycle Fuel Fabrication Laboratories (RFFL) at the Chalk River Laboratories, a facility designed to produce experimental quantities of MOX fuel for reactor physics and irradiation tests, conducted a fabrication campaign to manufacture this MOX fuel. The objective of the RFFL fabrication campaign was to produce 41 MOX fuel bundles with the ACR geometry, which is a modified 43-element CANFLEX® design. The ACR fuel bundle consists of 42 11.5 mm diameter elements in the outer rings and a 20 mm diameter centre element. Forty of these bundles were assembly welded and one was a demountable bundle that allows special elements to be installed and removed for fine structure experiments. Based on a study done to determine the composition of the simulated intermediate-burnup ACR fuel, the MOX fuel bundles contained different fuel compositions (i.e., different Pu and Dy contents and different ²³⁵U enrichments) for each ring of elements. The fabrication process used, from the starting fuel powders to the finished elements and bundles, will be presented, including qualification results and fabrication data. (author)