Nuclear reactor plant

A control and shutdown apparatus for a high temperature gas cooled nuclear reactor power plant comprising:

• a plurality of absorber channels extending vertically through a side reflector of a reactor wherein each absorber channel exhibits an upper terminal area, a lower terminal area and an absorber tube joining said upper and lower areas;
• first means for operational control an shutdown connected to said absorber channels including means for insertion of first absorber balls at said upper terminal area and removal of said balls at said lower terminal area and an absorber loop for circulating said first absorber balls from said lower terminal area to said upper terminal area;
• a second means for shutdown connected to said absorber channels including second absorber balls, at least one absorber element container means for storing said second balls located above said absorber channels and means for connecting said container means to said plurality of absorber channels at said upper terminal area in parallel with said means for insertion of first absorber balls;
• said second shutdown means is further for controlling insertion of said second absorber balls into said absorber channels;
• wherein said first absorber balls exhibit a spherical diameter which is correlated with the internal width of said absorber channels so that said first absorber balls largely fill the internal width of said channels while maintaining easy mobility within said channels;
• and
• said second absorber balls exhibit a substantially smaller spherical diameter than said first absorber balls;
• wherein each loop comprises beginning at the lower terminal area a first downwardly directed partial segment, connected by a tube bend to a second partial segment, extending with a downward slope in a radially outward direction, a third partial segment is connected to the second parallel segment, said third segment leading to above the reactor and passing into a fourth partial segment returning with a downward slope to the upper terminal area of said absorber channel;
• means for supplying gas in the second partial segment connected to a cold gas collector space for pneumatic transport of the first absorber balls upwards into the fourth partial segment, a pneumatic ball brake in the transition area from the third to the fourth partial segment and in the first partial segment, and a first metering feeder for feeding the first absorber balls in the upper terminal area of the absorber channels in the fourth partial segment;
• wherein said first metering feeder comprises a first and second blocking body arranged above each other at a distance approximately equal to the diameter of the first absorber balls, said blocking bodies being insertable by means of at least one drive transversely to the tubular segment into the internal space of said segment, wherein to interrupt the flow of the balls at least one blocking body is introduced if the flow of balls is to be released, to meter the flow of balls the lower blocking body initially blocks the partial segment, while the upper blocking body simultaneously releases the flow and subsequently the upper blocking body blocks and the lower blocking body releases the first absorber ball resting upon it;
• wherein the upper blocking body comprises two upper pins arranged horizontally adjacent to each other, the mutual distance whereof is sufficient for the interruption of the flow of balls, that the lower blocking body comprises two lower pins adjacent to each other and spaced apart just enough to interrupt the flow of balls, the lower pins in the area located under the upper pins are provided with recesses facing each other such that a first absorber ball may pass through the lower pins into the tube segment, both the upper and the lower pins are connected to the drive, whereby the two blocking bodies exhibit three different positions;
• in a first position the upper pins are located outside the segment and the lower pins with their full cross section in the internal space of the partial segment, in a second position the upper pins are located within the tube segment and the lower pins are located with their recesses in the internal space and, in a third position the upper and lower pins are outside the internal space.