This paper focuses on reliability analyses of Emergency Diesel Generator (EDG) systems in nuclear power plants. Reliability analyses are performed as part of the safety demonstration during the design phase of EDG systems in modernization and new build projects.
The main objective of reliability analyses is to demonstrate that reliability targets (safety goals) imposed on the EDG systems by the customer, regulators or design authorities within the licensing process are fulfilled. Reliability analyses also identify major contributors leading to the EDG unavailability. Based on this, design improvements are proposed to increase the reliability of the EDG design.
The paper includes a failure analysis of the EDG components using the operating experience of German plants. This analysis identifies major contributors to the EDG system failure. The results are compared with statistical analyses related to EDG failures in the nuclear industry, see e.g. Kancev et al. (2014).
The paper also focuses on the reliability of multi-diesel configurations, which result from replacing one large single EDG by a set of smaller EDG sets operating in parallel (with and without backup equipment). Different multi-diesel configurations are investigated using a fault tree analysis to gain insights for the design from a reliability perspective. The possibility of repairing backup equipment after failing in operation is considered in the reliability calculations.
Keywords: reliability analysis, FMEA, multi-diesel configuration.

References

D. Kancev, FA. Buchac, B. Zerger, M. Maqua and D. Wattrelos (2014). Statistical analysis of events related to emergency diesel generators failures in the nuclear industry. Nuclear Engineering and Design 273, 321-331