[en] Important decisions related to the kind of reactors to be used for the disposition of the surplus weapons-grade plutonium are going to be based on calculations. Benchmarking computational methods in all aspects of the fuel cycle with measured data is then an obvious necessity. Analysis of public domain data reveals that the cycle-2 irradiation in the Quad Cities-1 boiling water reactor is the most recent U.S. destructive examination, involving the irradiation of five mixed-oxide (MOX) assemblies using 80 and 90% fissile Pu, quite close to weapons-grade Pu isotopic. Such measurements are rare, and they might be the only source of information to quantify differences in key neutronics parameters between high-fissile Pu systems and the well-characterized use of reactor-grade Pu. The pin neutronic performances for the UO₂ and MOX fuels are compared with assembly-level calculation in which ∼20% of the pins are MOX pins surrounded by UO₂ pins. For MOX rods, HELIOS models the chains for the isotopes of uranium and plutonium reasonably well when compared with measured data at ∼12,000 MWd/tonne. However, indications are that the amounts of heavier actinides are underpredicted. Measurements and calculations of the relative pin power distribution for the last few weeks of the irradiation and the burnup are fairly consistent. The critical effects of the contribution of the 0.296-eV resonance to the production of higher actinides and the destruction of ²³⁹Pu are discussed