Document: NUREG-0800
Document ID: 47506195-5ce2-4c13-a914-02847d53c193
Document Type: srp
Title: of Reference 4.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340570.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.5.2
CFR Part: 
CFR Title: 

Content:
information contained in References 1 through 3 and Reference 5. These references also contain acceptable calculational techniques for the implementation of these criteria. The use of other approaches meeting the intent of these criteria can also be considered if adequate justification is provided. 3.7.3-6 Rev. 2 - August 1989 a. A minimum acceptable analysis must incorporate at least two horizontal modes of combined fluid-tank vibration and at least one vertical mode of fluid vibration. The horizontal response analysis must include at least one impulsive mode in which the response of the tank shell and roof are coupled together with the portion of the fluid contents that moves in unison with the shell. Furthermore, at least the funda- mental sloshing (convective) mode of the fluid must be included in the horizontal analysis. b. The fundamental natural horizontal impulsive mode of vibration of the fluid-tank system must be estimated giving due consideration to the flexibility of the supporting medium and to any uplifting tendencies for the tank. It is unacceptable to assume a rigid tank unless the assumption can be justified. The horizontal impulsive-mode spectral acceleration, S is then determined using this frequency and the appropriate dampfg for the fluid-tank system. Alternatively, the maximum spectral acceleration corres- ponding to the relevant damping may be used. c. Damping values used to determine the spectral acceleration in the impulsive mode shall be based upon the system damping associated with the tank shell material as well as with the SSI, as specified in References 3 and 10. d. In determining the spectral acceleration in the horizontal convective mode, S. the fluid damping ratio shall be 0.5 percent of critical dampinga nless a higher value can be substantiated by experimental results'. e. The maximum overturning moment, Mo, at the base of the tank should be obtained by the modal and spatiaT combination methods discussed in subsection II of SRP