OBJECTIVE: Assessment of levelized cost of produced energy is important for power system planning. It is important to assess many parameters. Some of them are important in mid-term (overnight cost, financial conditions), and some in long-term (fuel costs). Those assessments have uncertainties. To properly assess levelized cost, uncertainties must be evaluated and compared across technologies. METHOD: Uncertainty of assessment of selected parameters and of levelized cost of produced energy in Nuclear Power Plant has been compared with uncertainties of corresponding parameters and levelized costs of produced energy from other base-load power plants, coal-fired and gas-fired power plants. RESULTS: Some correlations between parameters have been determined, especially between overnight costs, and between fuel costs. Many parameters have medium or high correlation with oil price, including parameters important for determining nuclear fuel price. Inclusion of those correlations is in most calculations important. It is especially important if only some parameters of different producing technologies are compared, like cost effectiveness of nuclear power plant and gas-fired power plant depending solely on overnight cost of nuclear power and gas cost. Recent projections put current uranium supply as enough for 100 years, if usage remains the same as today. Several methods for increased duration of uranium supply have been identified. All those methods can significantly increase nuclear fuel price, but its influence on levelized cost of produced energy from nuclear power plants is not very significant. CONCLUSION: Even with highest predicted rise in uranium costs nuclear power plant is still cost-effective compared to gas-fired and coal-fired power plants.