Large penetration of wind generating units in power systems necessitates a flexible unit commitment tool to handle the intermittent nature of these units as well as demand. Moreover, power system operators face not only the risks of wind power curtailments, but also probable unit outages. Therefore, assessing a tradeoff between operational costs and such risks is very important. In the proposed approach, the probability of the residual demand falling within the up-and-down spinning reserve imposed by n - 1 security criterion is converted into a risk index. A new biobjective probabilistic risk/cost-based unit commitment model is proposed to simultaneously minimize both the operational costs and risk. The novel formulation presented provides a new power redispatch process to satisfy up-and-down ramp rate constraints. A new operational-cycles-based unit commitment algorithm is developed. The approach profits from a new nondominated sorting backtracking search optimization algorithm for extracting the Pareto-optimal set. The proposed approach is shown to provide superior results when applied to two test systems: 1) 10-unit and 2) IEEE 118-bus, 54-unit system.