Control rod for pressurized water nuclear reactor, has absorber pencils carried by spider and constituted by boron that is enriched in boron-ten with specific percent of atomic content

The rod (20) has absorber pencils (40) carried by a spider (42) and constituted by soluble boron i.e. boric acid, that is enriched in boron-10 with an atomic content higher than 30 or 40 percent. The spider comprises a pommel (44) to connect the rod to a displacement mechanism. Wings (45) are integrated to the pommel on which the pencils are fixed. Each pencil comprises a tube (46) for containing a stack of pellets (48) that are made of boron carbide. The tube is closed at its upper end by a stopper (50), where the tube and the stopper are made of steel. An independent claim is also included for a pressurized water nuclear reactor including a core. Cette grappe de commande (20) pour réacteur nucléaire à eau pressurisée comporte une araignée (42) et des crayons absorbants (40) portés par l'araignée, les crayons absorbants (40) comprenant du bore enrichi en bore 10.