Prestressed nuclear pressure vessel has removable top closure - with primary and secondary fixings esp prestressed bolts

摘要

A prestressed concrete pressure vessel has a removable top closure held down by primary and secondary holding down device, which are anchored to the concrete of the pressure vessel itself. The secondary holding devices pass through the concrete of the closure, while the primary holding down devices pref. pass through it also, via tubes. In the prefd. arrangement, the primaries are bolts prestressed by nuts onto a bearing plate fitted around the top end of the tube, while the secondaries are bolts, also prestressed by nuts onto bearing plates and anchored into bearing plates which themselves may be the anchorages of the prestressing cables in the side wall of the vessel. Spacers provide a gap between closure and vessel wall. There is also pref. a bearing plate at the primaries. The vessel is used in e.g. boiling water, high temperature or fast breeder reactors.