Two models which are designed to perform fuel inventory calculations without the use of detailed and expensive computer programs have been developed. The accuracies of these models have been evaluated by comparing results obtained with them to measurements of discharged fuel from the Yankee Rowe reactor. In general, the models predict the 235U depletion to within ±2% of the measured values and the total plutonium production to within ±5% for fuel batches consisting of about 70 fuel assemblies. Uncertainties in the computational results have been ascertained to be about ±2% for the total 235U content and ±3% for the total plutonium production.