A detailed evaluation of the fuel-burnup dependent power distribution and the scram reactivity for the PIUS reactor design has been performed. The analyses were carried out using the CPM lattice physics and NODE-P2 core neutronics/thermal-hydraufics codes, and are based on the information provided in the PIUS Preliminary Safety Information Document.Cycle depletion calculations were performed for a set of nine representative initial core loadings and the threedimensional core power distributions were determined. These calculations indicate that the PIUS radial FAh and total Fa power peaking is stronger than that indicated by the PIUS reference-design values.The scram reactivity resulting from the injection of highly borated pool water was calculated for a series of timedependent linear ramp and square-wave pool flows. The three-dimensional distribution of the borated pool water throughout the core was modeled and the spatial reactivity effects of the distributed boron were determined. For pool flows that increase as a linear ramp, the spatial reactivity effects of the distributed boron were very small. In this case, a constant core-average boron reactivity coefficient can be used to model the PIUS scram reactivity.

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At present a large number of cases of cracking in stay vanes of Kaplan and Francis turbines are known [i, 2].Cracks reach considerable sizes, their elimination leads to stopping the equipment~ and in the case of untimely inspection the development of cracks can lead to braking off of the vane, i.e., to a severe accident.An investigation of the causes of cracking requires the conduction of acomplex of research works, including a determination of the stress state of the vanes (residual, static, and dynamic stresses), vibration tests, and a study of thecharacteristics of~the corrosion fatigue strength of the material and welded joints.

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