Structural Analysis Results of Thermal, Operating and Seismic Analysis for Hanford Single-Shell Tank Integrity - 12261
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 (United States)
Since Hanford's 149 Single-Shell Tanks (SSTs) are well beyond their design life, the U.S. Department of Energy has commissioned a state of the art engineering analysis to assess the structural integrity of the tanks to ensure that they are fit for service during the cleanup and closure phase. The structural integrity analysis has several challenging factors. There are four different tank sizes in various configurations that require analysis. Within each tank type there are different waste level and temperature histories, soil overburden depths, tank floor arrangements, riser sizes and locations, and other on-tank structures that need to be addressed. Furthermore, soil properties vary throughout the tank farms. This paper describes the structural integrity analysis that was performed for the SSTs using finite element models that incorporate the detailed design features of each tank type. The analysis was performed with two different models: an ANSYS static model for the Thermal and Operating Loads Analysis, and an ANSYS dynamic model for the seismic analysis. The TOLA analyses simulate the waste level and thermal history and it included a matrix of analysis cases that bounded the material property uncertainties. The TOLA also predicts the occurrence of concrete thermal degradations and cracking, reinforcement yielding, and soil plasticity. The seismic analysis matrix included uncertainty in waste properties, waste height and the soil modulus. In seismic analysis the tank concrete was modeled as a linear elastic material that was adjusted for the present day degraded conditions. Also, the soil was treated as a linear elastic material while special modeling techniques were used to avoid soil arching and achieve proper soil pressure on the tank walls. Seismic time histories in both the horizontal and vertical directions were applied to the seismic model. Structural demands from both Thermal and Operating Loads Analysis and seismic models were extracted in the form of section forces and moments for sections throughout the tank under the appropriate load combinations. These demands were evaluated against the American Concrete Institute (ACI) code requirements for nuclear safety-related concrete structures as defined in ACI-349-06. Structural integrity analysis of Hanford's Type II and Type III Single-Shell Tanks (SSTs) was performed using finite element models (ANSYS software) that incorporate the detailed design features of each tank type. The analysis was performed with two different models: a static model for the Thermal and Operating Loads Analysis, and a dynamic model for the seismic analysis. Structural demands from both Thermal and Operating Loads Analysis and seismic models were evaluated against the American Concrete Institute (ACI) code requirements for nuclear safety-related concrete structures as defined in ACI-349-06. The ratio of demand to capacity (D/C) was reported as a measure of structural integrity for the applicable ACI-349-06 load combinations. Although the Type II and Type III analysis matrix showed varying demands depending on the material combinations, all of the tank regions that are critical to structural stability passed the ACI 349-06 acceptance criteria. This was true for the conservative combination of maximum recorded thermal loads and maximum soil overburden depth combined with the analysis matrix of bounding material property combinations. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 22293546
- Report Number(s):
- INIS-US-14-WM-12261; TRN: US14V1202115070
- Resource Relation:
- Conference: WM2012: Waste Management 2012 conference on improving the future in waste management, Phoenix, AZ (United States), 26 Feb - 1 Mar 2012; Other Information: Country of input: France; 13 refs.
- Country of Publication:
- United States
- Language:
- English
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