After loss of power and reactor cooling capability at the Fukushima Daiichi nuclear power plant due to an extreme seismic event, the U.S. nuclear energy industry developed a diverse, flexible approach to implement the lessons learned, called FLEX. FLEX builds on earlier safety steps by providing an effective and efficient way to make U.S. nuclear energy facilities even safer, by addressing Nuclear Regulatory Commission recommendations. These recommendations include systems such as additional layers of backup power by generators, battery packs, pumps, and air compressors in multiple on-site and off-site locations, to be available if all plant backup equipment is insufficient. A 21,000 gallon frac tank will supply backup water storage to reactors at a commercial nuclear power plant during a beyond design basis event. This paper presents methodology for seismic structural analysis of the frac tank for two times the operating basis earthquake (OBE) and safe shutdown earthquake (SSE) response spectra including the Lindley-Yow method of analysis to properly account for the rigid response component. We perform fluid-structure interaction analysis using the computer program NASTRAN. Multiple tank fill conditions are considered, and evaluation is performed to ensure all component stresses are below allowable values per ANSI/AISC N690-12 and 350-10. The tank is evaluated for global stability using nonlinear sliding and overturning provisions of Appendix A of ASCE/SEI 43-05.
What audience will learn:
- How to calculate appropriately damped input response spectra per Regulatory Guide 1.61 and NUREG/CR-6728 given 5% damped Operating Basis Earthquake and Safe Shutdown Earthquake Ground Response Spectra input.
- Methodology for performing fluid-structure interaction analysis with response spectra input and the Lindley-Yow method to account for the rigid response component, using the computer program NASTRAN.
- Structural evaluation of a frac tank based on analysis noted above, and how to perform global stability evaluation using nonlinear sliding and overturning provisions of Appendix A of ASCE/SEI 43-05.