Patent Number: 047284870
Section: claims

1. A burnable poison type control rod for use in a fuel assembly of a nuclear reactor, comprising: (a) an upper end portion including  (b) a lower end portion including  (c) an intermediate portion including  (d) an upper connection fixedly connecting said upper end portion to said intermediate portion by rigidly connecting said elongated upper tubular extension at its lower end with said upper end of said middle tubular section adjacent said upper end cap; and  (e) a lower connection fixedly connecting said lower end portion to said intermediate portion by rigidly connecting said elongated lower tubular extension at its upper end with said lower end of said middle tubular section adjacent said lower end cap.  (a) an upper end portion including  (b) a lower end portion including  (c) an intermediate portion including  (d) an upper connection fixedly connecting said upper end portion to said intermediate portion by rigidly connecting said elongated upper tubular extension at its lower end with said upper end of said middle tubular section adjacent said upper end cap, said upper tubular extension having a hollow chamber formed therein which defines an upper space extending between said upper end plug and said upper end cap on said upper end of said middle tubular section of said respective upper end and intermediate portions of said rod, said space being devoid of nuclear fuel and burnable poison material; and  (e) lower connection fixedly connecting said lower end portion to said intermediate portion by rigidly connecting said elongated lower tubular extension at it upper end with said lower end of said middle tubular section adjacent said lower end cap, said lower tubular extension having a hollow chamber formed therein which defines a lower space extending between said lower end plug and said lower end cap on said lower end of said middle tubular section of said respective lower end and intermediate portions of said rod said space being devoid of nuclear fuel and burnable poison material. 2. The rod as recited in claim 1, wherein said intermediate portion further includes a spring disposed in said chamber of said middle tubular section between one of said upper end lower end caps and said burnable poison material contained in said chamber. 3. The rod as recited in claim 1, wherein said burnable absorber material is in the form of a borosilicate glass tube disposed in said chamber of said middle tubular section between said upper and lower end caps. 4. The rod as recited in claim 1, wherein said burnable poison material is in the form of a stack of pellets containing boron disposed in said chamber of said middle tubular section between said upper and lower end caps. 5. The rod as recited in claim 1, wherein said upper tubular extension has a hollow chamber formed therein which defines an upper space extending between said upper end plug and said upper end of said middle tubular section of said respective upper end and intermediate portions of said rod. 6. The rod as recited in claim 5, wherein said lower tubular extension has a hollow chamber formed therein which defines a lower space extending between said lower end plug and said lower end of said middle tubular section of said respective lower end and intermediate portions of said rod. 7. A burnable poison type control rod for use in a fuel assembly of a nuclear reactor, comprising: