[en] Reactor physics computer programs are important tools that will be used to estimate mixed oxide fuel (MOX) physics performance in support of weapons grade plutonium disposition in US and Russian Federation reactors. Many of the computer programs used today have not undergone calculational comparisons to measured data obtained during reactor operation. Pin power, the buildup of transuranics, and depletion of gadolinium measurements were conducted (under Electric Power Research Institute sponsorship) on uranium and MOX pins irradiated in the Quad Cities-1 reactor in the 1970's. These measurements are compared to modern computational models for the HELIOS and SCALE computer codes. Good agreement on pin powers was obtained for both MOX and uranium pins. The agreement between measured and calculated values of transuranic isotopes was mixed, depending on the particular isotope