In this work we analyze the impact of performing process design and process operation changes on the nonlinear open-loop operability of a polymerization reactor. The singularity theory is used to learn how those sort of changes affect the non-linear behaviour of the polymerization reactor. Based on those results a set of global bifurcation diagrams are obtained which display the different operating regions; from these diagrams it becomes clear the operability implications of such operating regions. Using the global bifurcartion diagrams the effect of changes in the area and volume of the reactor are tried; similarly changes in the Cooling water flowrate and feed stream conditions were studied. The results clearly show that these changes have different impact on the non-linear operability characteristics of the polymerization reactor. Using these results the closed-loop control implications are easier to understand.