a green closed loop supply chain network design considering operational risks under uncertainty and solving the model with nsga ii algorithm

in today’s growing competitive environment, supply chain management has been widely focused by firms as a critical issue. consequently, the organization’s activities are influenced in order to achieving quality improvement, cost reduction and customer satisfaction in production process. recently, pollution and greenhouse effects have focused the researchers’ attention on planning and executing networks in which environmental problems and economical aspects are considered simultaneously. in this paper, a multi-layer, multi-product and multi-period supply chain network with product return will be studied. the operation risks are assumed as failures occurring in supplier and plant segments. the mathematical modeling will select the best suppliers according to selling price, transportation costs and the average of deficiency. uncertainty is considered by means of fuzzy approach. the proposed multi-objective fuzzy model is first defuzzified using jimenez technique and then it is solved by th method. as the supply chain problems are determined as np-hard problems, in this study we took advantage of nsga ii in a large-scale case.