Containment prestressing loads

Great care must therefore be exercised when applying realkalization to structures containing prestressing steel under load. Very careful monitoring must be carried out to ensure that the steel is completely shielded from the risk of hydrogen evolution or the steel must be carefully tested to ensure that it has no susceptibility to embrittlement from nascent hydrogen. These issues are discussed in Miller (1994). 

The containment shell is analyzed for individual and various combinations of loading cases of dead load, live load, prestress, temperature, and pressure. The design output includes direct stresses, shear stresses, principal stresses, and displacements of each nodal point. Stress plots which show total stresses resulting from appropriate combinations of loading cases are made and areas of high stress identified. If necessary, the modulus of elasticity is corrected to account for the nonlinear stress-strain relationship at high stresses. Stresses are then recomputed if a sufficient number of areas requiring attention exist. 

In any computer package involving 2- and 3D finite-element technique, Table AIB.l giving analytical formulation can be simulated to analyse the liner between the studs, standpipes and cooling pipes. For the global analysis of the pressure and containment vessels, these local effects can form the worst case. The vessel can be analysed with and without the contribution of the liner. Under ultimate conditions the liner local areas must be thoroughly assesed prior to the final decision of the factor safety above the elastic conditions under (pressure + prestress + temperature) the combined loading ... 

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