scholarly journals Investigation of High Energy Arcing Fault Events in Nuclear Power Plants

Author(s):  
Heinz Peter ◽  
Marina Rowekamp
2020 ◽  
Vol 6 (4) ◽  
Author(s):  
Marwan Charrouf ◽  
Storm Kauffman ◽  
Jin-Kyoo Yoon ◽  
Sang-Gyu Lee ◽  
Taejoon Kim

Abstract The effects of postulated accidents, including dynamic effects of pipe ruptures, must be analyzed for licensing of nuclear power plants (NPPs). Applicants and licensees of NPPs have struggled to address U.S. Nuclear Regulatory Commission (NRC) expectations to assess if high energy line break (HELB) jet impingement on structures and components can lead to dynamic amplification, and to accurately simulate blast wave-induced loadings. In this paper, evaluation of the potential for load amplification and occurrence of resonance conclusively demonstrates that the phenomenon does not occur. In a HELB, several physical parameters of jets issuing from a ruptured pipe—such as nonequilibrium condensation of steam, unsteady separation between the jet exit and target, nonorthogonal alignment of jet axis to impingement surface, uneven impingement surfaces, or mismatch of jet excitation frequency and target natural frequency—prevent occurrence of the phase lock conditions needed to initiate and maintain a resonance. The analytical approach to evaluate the blast wave-induced loading applied a pressure vessel burst (PVB) correlation instead of performing computational fluid dynamics (CFD) analysis for all break locations. Three-dimensional (3D) CFD analysis of blast wave transient propagation provided the basis to develop benchmarking factors for use with the PVB correlation. The simplified methodology utilizes shockwave reflection, shape, and environment factors for application to impacted targets, which significantly reduces the amount of time to evaluate all break locations. The modified PVB method is also more appropriate than an explosion-type correlation to model the blast wave pressures from steam pipe breaks.


Author(s):  
Sivadol Vongmongkol ◽  
Asgar Faal-Amiri ◽  
Hari M. Srivastava

Crushable material has widely been used as an engineering solution for energy absorption devices among many industries. Abnormal and severe accident loads in the design of nuclear power plants are required to be addressed in order to comply with Nuclear Regulatory Commission (NRC) requirements which makes the crushable material more suitable in its highly dynamic application. One of the severe loads is from a postulated high energy piping system rupture. Its effects are required to be mitigated so that the proper operation of safety related systems, structures and components (SSC) of these facilities is assured. The postulated pipe rupture loads are among the highest loads that need to be addressed in the design process of nuclear power plants. The impact forces produced by the postulated pipe rupture are typically being absorbed by energy absorption devices called “Pipe Whip Restraints” in which the restraints can minimize the loads affecting the SSCs to within an acceptable limit. This paper provides a simplified closed-form solution to determine the energy absorbing characteristic that will help to design these devices. This paper will also provide a comparison between results of the proposed simplified closed-form solution equations to the experimental test results and the calculated results using finite element analysis.


Author(s):  
Marjorie B. Bauman ◽  
Richard F. Pain ◽  
Harold P. Van Cott ◽  
Margery K. Davidson

2010 ◽  
pp. 50-56 ◽  
Author(s):  
Pablo T. León ◽  
Loreto Cuesta ◽  
Eduardo Serra ◽  
Luis Yagüe

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