The sources of radioactive contamination of the primary coolant by fission products when the unit is operating at the rated power are as follows: defect fuel elements with gas leakiness and substantial damages, surface contamination of the outer surfaces of fuel claddings, superficial contamination of structural materials of fuel assemblies.
Reinforced concrete bridges with skew intersection of obstacles (the skew in the plan bridges) with beam cross-ribbed span structures have characteristic constructive differences in the layout the floor beam system compared to straight systems. In particular, it is the shift in the plan of the main beams on the supports and skew or straight orientation of the transverse beams (diaphragms) that unites main beams across the span into beam cross-ribbed grillage. These features considerably complicate the theoretical creation of their calculation models of spatial calculation.