scholarly journals Understanding seismic design criteria for Japanese Nuclear Power Plants

10.2172/93879 ◽  
1995 ◽  
Author(s):  
Y J Park ◽  
C H Hofmayer ◽  
J F Costello
Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4435 ◽  
Author(s):  
Gyeong-Hoi Koo ◽  
Jong-Sung Kim ◽  
Yun-Jae Kim

In this paper, the feasibility study to develop strain-based seismic design criteria applicable for the components of nuclear power plants are carried out as an alternative rule to the current stress-based criteria. To do this, two acceptance criteria are investigated through the detailed example of an application for the surge line nozzles in a nuclear steam supply system, which are known as one of the seismic fragile components in nuclear power plants. These strain-based seismic design criteria are primarily to prevent two types of failure modes, such as a ductile fracture and a cyclic fatigue-induced damage due to continuous large amplitude cyclic loads during seismic event. Through the example problem, the required procedures are described step-by-step with calculations of an accumulated plastic strain, triaxiality factor by the elasto-plastic seismic analysis using the finite element method. For a precise inelastic seismic analysis, the Chaboche kinematic and Voce isotropic hardening material parameters are identified by the test data and used for an inelastic material model. The results by the strain-based criteria are compared with those by the ASME (American Society of Mechanical Engineers) stress-based design criteria for a service level D limits. From the study, it is expected that the strain-based seismic design method investigated in this paper will be beneficial for the nuclear components, especially when the design basis earthquakes are large enough to cause severe plastic strains at a critical location.


Author(s):  
Jim Xu ◽  
Sujit Samaddar

The U.S. Nuclear Regulatory Commission (NRC) established a new process for licensing nuclear power plants under Title 10 of the Code of Federal Regulations (10 CFR) Part 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” which provides requirements for early site permits (ESPs), standard design certifications (DCs), and combined license (COL) applications. In this process, an application for a COL may incorporate by reference a DC, an ESP, both, or neither. This approach allows for early resolution of safety and environmental issues. The COL review will not reconsider the safety issues resolved by the DC and ESP processes. However, a COL application that incorporates a DC by reference needs to demonstrate that pertinent site-specific parameters are confined within the safety envelopes established by the DC. This paper provides an overview of site parameters related to seismic designs and associated seismic issues encountered in DC and COL application reviews using the 10 CFR Part 52 process. Since DCs treat the seismic design and analysis of nuclear power plant (NPP) structures, systems, and components (SSC) as bounding to future potential sites, the design ground motions and associated site parameters are often conservatively specified, representing envelopes of site-specific seismic hazards and parameters. For a COL applicant to incorporate a DC by reference, it needs to demonstrate that the site-specific hazard in terms of ground motion response spectra (GMRS) is enveloped by the certified design response spectra of the DC. It also needs to demonstrate that the site-specific seismic parameters, such as foundation-bearing capacities, soil profiles, and the like, are confined within the site parameter envelopes established by the DC. For the noncertified portion of the plant SSCs, the COL applicant should perform the seismic design and analysis with respect to the site-specific GMRS and associated site parameters. This paper discusses the seismic issues encountered in the safety reviews of DC and COL applications. Practical issues dealing with comparing site-specific features to the standard designs and lessons learned are also discussed.


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