Then more effects could be focused on these important factors to improve the safety level. Probably it is these important factors that push the global behavior of the engine into a critical zone, while other parameters have almost no influence on its behavior. Finally, it is inevitable that uncertainties exist between the design model and the real engine.
These uncertainties may arise from manufacture, operation environment, maintenance, etc. After the safety assessment, some special measures should be taken to ensure that the actual safety level of the most important factors is consistent with the safety level used in SSA, if necessary. Safety assessment should hence benefit from the large amount of on-going research devoted to developing sensitivity analysis within large industrial engineering and modeling