Nuclear reactor installation

摘要

In a nuclear reactor installation having a containment shell, a live steam line leading outwardly from the containment shell, a fast-acting shut-off valve connected in the steam line and having a flow cross section corresponding to the cross section of the steam line, the shut-off valve including a normally open main valve disk which is actuatable to close in response to pressure from a leak in the steam line, pressure dependent means associated with the main valve disk for sensing a pressure higher than operating pressure of the steam line, an opening mechanism includes a piston-actuated auxiliary valve disk disposed in a cut-out formed in the main valve disk and having an area equal at most to one-half the flow cross-sectional area of the shut-off valve, the auxiliary valve disk being operable by the pressure-dependent means to open the cut-out opening when a pressure higher than operating pressure of the steam line is sensed by the pressure dependent means.