In 2003, the report « The Economics of Reprocessing vs. Direct Disposal of Spent Nuclear Fuel » was issued. The authors made a detailed comparison of the cost of various options of fuel reprocessing. It is based on a major review of existing literrature and uses systematically sensitivity analyses and Monte Carlo methods to estimate the robustness of the model and conclusions to assumptions. It is one of the most cited work in the field. The authors made very clear that even with overwelmingly favorable assumptions, the reprocessing option wheter in PWR or in FR would be uneconomic in a very wide range of input hypothesis. In this presentation we will show that an error was made in the estimation of the annual loading of blankets for the model with Fast Breeder Reactors. Calculation was done as if the blankets were producing 100% of the power of the reactor when they usually produce less than 10%. This errors multiplies by more than ten the need for blanket fuel fabrication and reprocessing which has a very adverse effect on the global economic equation of Fast Breeder Aeactors. The authors made their most important calculation sheets available on the internet which allows transparency and the reproduction and the correction of the results. We will present corrected versions of the key figures of the report together with some alternative conclusions. This error demonstrates the needs for open benchmarks and active forums where experts can check the robustness of their interdisciplinary tools. It also demonstrates that the debate about the opportunity of advanced fuel cycle is much more open than that report demonstrated.This refocuses the debate on the key technical-economics assumptions in favor of the different options. What is the cost-benefit analysis of blankets in SFR ? Is uranium price or visibility of its potential reduced availability of any relevance to the debate ? How are the uncertainties in the costs of advanced fuel cycles fuzzing the debate ? Are economical arguements of any use for actual decision making regarding fuel cycle questions or even energy issues ?