Control organization and method for a nuclear reactor

Claim 1

IN A THERMAL NUCLEAR REACTOR A CORE DISPOSED WITHIN A SUITABLE VESSEL AND THROUGH WHICH A COOLING FLUID IS DIRECTED, A PLURALITY OF ELONGATED HOUSING MEMBERS IN THE CORE AND EXTENDING THEREABOVE PROVIDING A PLURALITY OF INDEPENDENT PASSAGEWAYS HAVING A LOWER PORTION IN THE REGIN OF THE CORE AND AN UPPER PORTIN ABOVE THE CORE, SEPARATE MEANS OPERATIVE TO CONVEY A FLUID UP THROUGH EACH PASSAGEWAY, EACH OF SAID SEPARATE MEANS INCLUDING MEANS EFFECTIVE, PER SE, TO CONTROL THIS FLUID FLOW THROUGH EACH PASSAGEWAY, THIS LAST NAMED MEANS HAVING A FIRST POSITION WHEREIN IT IS EFFECTIVE TO ESTABLISH A FULL FLOW OF THE FLUID UP THROUGH THE PASSAGEWAY AND A SECOND POSITION WHERE IT IS EFFECTIVE TO PROVIDE ONLY A MUCH DECREASED FLOW OF THE FLUID UP THROUGH THE PASSAGEWAY, MOVABLE MEANS CONFINED IN EACH OF SAID PASSAGEWAYS BUT MOVABLE BETWEEN THE UPPER AND LOWER PORTION THEREOF AND BEING CAPABLE OF BEING GENERALLY WHOLLY CONTAINED IN EITHER THE UPPER OR LOWER PORTIONS, SAID MOVABLE MEANS CONTAINING A MATERIAL THAT HAS A HIGH NEUTRON ABSORPTION CROSS SECTION AND BEING MOVED BY GRAVITY INTO SAID LOWER PORTION WHEN SAID DECREASED FLOW CONDITION PREVAILS BUT MOVED INTO SAID UPPER PORTION WHEN SAID FULL FLOW CONDITION PREVAILS.