The fuel booster pump is one of the most vulnerable physical assets in an operating engine due to the harsh environmental and operational conditions. However, because of its high structural complexity and extreme operational conditions, the reliability design of the fuel booster pump becomes especially difficult, particularly by means of experiments. Thus, to overcome such a problem, advanced simulation techniques have become adequate solutions for the reliability assessment and analysis of a fuel booster pump at the design stage. In this paper, by considering the effects of the uncertainties of multiple design parameters, fatigue life distributions of the four key components (which are the sealing bolt, spline shaft, graphite ring, and inducer, respectively) in a fuel booster pump were first predicted by PoF-based reliability simulations. Then, through further sensitivity analysis on each key component, the design parameters most sensitive to the component mean fatigue life were detected from a total of 25 candidate parameters. These parameters include the “nominal diameter” and “preload” for the sealing bolt, “major and minor diameters of the small spline” for the spline shaft, “inside diameter” for the graphite ring, and “fuel pressure on the blade front surface” for the inducer, respectively. These sensitivity results were found to be in good agreement with the results from the qualitative cause analysis on each key component.

C-ring, whose sealing behavior is the key to the sealing structure, is one of the main seal-rings for a reactor pressure vessel (RPV). A finite-element model with less simplification has been established using ANSYS APDL to simulate the sealing behavior of C-ring. The numerical results, including sealing-behavior curve, specific pressure, and springback value, have been compared with test results at 7.67%, 8.42%, and 8.09% compression ratios, respectively. It confirms the validity of this numerical simulation method. With the numerical method, the deformation and stress distribution and sealing-behavior curve of C-ring can be obtained. The behavior curve can be divided into five sections. At 10% compression ratio, the peak contact stress is 501 MPa, the contact width is 3.22 mm, the total springback value is 0.460 mm, the effective springback value is 0.332 mm, and the linear load is $788N/mm$. As C-ring is composed of three parts, three models, i.e., spring-only, spring with inner lining, and spring with two linings, have been simulated to study the effect of the contact states among each part on sealing behavior.

The lack of information on the correlation between root causes and corresponding control criteria in the importance calculation of root causes of design problems results in less accurate determinations of core problems. Based on the interaction between customer needs, bad product parameters, and root causes, a hierarchical representation model of the design problem is established in this paper. A network layer of bad parameters, including various types of correlations, and a control layer, including technical feasibility and cost, are constructed. Then, a method based on the network analytic hierarchy process is proposed to rank the importance of root causes of the design problem and determine the core problems. Finally, a product design process based on the core problem solving is established to assist designers with improving design quality and efficiency. The design for the coolant flow distribution device in the lower chamber of a third-generation pressurized water reactor is employed as an example to demonstrate the effectiveness of the proposed method.

1\. Objectives Irradiation hardening is one of the most important aging effects of reactor pressure vessel (RPV) steel in long-term service. A number of studies have indicated that irradiation hardening is mainly caused by irradiation induced defects, such as dislocation loops and precipitates. It is essential to set up microstructure scale models about how these defects be