Dynamic stresses on reactor pressure vessel internals at blowdown

Wave dispersion phenomena which are founded on the compressibility of the fluid (coolant) do not usually play a dominant role. Wave dispersion phenomena which are founded on the flexibility of the structure or the fluid-structure interaction, on the other hand, are usually of considerable significance. The realization that the compressibility of the fluid can frequently be disregarded leads to a considerable simplification of the theoretic models and calculation programs. So, for example, a three-dimensional analysis on the stress placed on the core supports can be carried out at an acceptable expense. On the other hand, the result is that, when compressibility is taken into consideration, the method of virtual fluid masses or the observance of only one wave cycle is not generally sufficient. (orig./DG)