Thermal-hydraulic analyses of nuclear plant components and structures are used to determine loadings from fluid flow at various temperatures to support structural integrity evaluations.
Structural Integrity conducts a full array of steady-state and transient thermal-hydraulic analyses, using first principle methods, ANSYS CFX Computational Fluid Dynamics (CFD) software or other specialized software, including proprietary codes. Examples of project experience involving complex thermal-hydraulic analyses include: (i) cold and hot fluid mixing at piping tee-junctions, (ii) interaction of reactor coolant system swirl penetration with cold in-leakage in attached branch piping, (iii) pressurizer surge line and vessel stratification during insurge and outsurge transients, and (iv) blow-down in a BWR annulus after a postulated recirculation line break.
Soil-structure interaction (SSI) models the interdependency in behaviors of structures and their supporting/surrounding foundations. SSI occurs as a physical phenomenon for any structure-foundation system (under static or dynamic loading), but becomes particularly important when structures are massive, embedded within the ground, and/or founded on flexible subsurface materials (e.g., ranging from soft rock to soft soil).
Such conditions are encountered at a significant number of nuclear plant structures for various input load conditions (static case, seismic, aircraft impacts, explosions and fluid impacts, etc.). SSI analysis is most often employed in the dynamic case, where both kinematic and inertial interaction effects, as well soil nonlinearity (for shear moduli and damping) and motion incoherence are addressed for accurate/realistic assessment. Appropriate modelling of nonlinearity and incoherence effects often provides benefits of reduction of in-structure responses over significant ranges of vibration frequencies and input load intensities. Structural Integrity Associates performs SSI studies for the various static and/or dynamic load conditions, and employs industry accepted methods and software (e.g., SASSI, in the case of seismic loading). The scope of approaches employed by Structural Integrity for SSI includes deterministic and probabilistic methods, ranging from simplified to highly advanced.