Patent Number: 
Section: claims

1. A radiation induced growth indication apparatus for the determination of radiation induced growth of a pressurized water reactor nuclear fuel assembly positioned in a reactor core having an upper core support plate, the nuclear fuel assembly including an upper tie plate, said apparatus comprising: an inelastically compressible structural member configured to be disposed between and to be in contact with the upper tie plate and upper core support plate, wherein said compressible structural member is configured to be compressed due to a movement of the upper tie plate relative to the upper core support plate as a result of radiation induced growth of the fuel assembly. 2. The radiation induced growth indication apparatus as in  claim 1  wherein the inelastically compressible structural member is a hollow tube. claim 1 3. The radiation induced growth indication apparatus as in  claim 2  wherein the hollow tube compresses in response to the application of a compressible force of 10 pounds or less. claim 2 4. The radiation induced growth indication apparatus as in  claim 3  wherein the hollow tube has a circumference and further comprises a plurality of holes through the circumference. claim 3 5. The radiation induced growth indication apparatus as in  claim 2  wherein the inelastically compressible structural member is a rod. claim 2 6. The radiation induced growth indication apparatus as in  claim 5  wherein the rod is positioned at one end into an aperture in an upper surface of the fuel assembly upper tie plate. claim 5 7. The radiation induced growth indication apparatus as in  claim 6  wherein the rod compresses in response to the application of a compressive force of 10 pounds or less. claim 6 8. A radiation induced growth indication apparatus for the determination of radiation induced growth of a pressurized water reactor nuclear fuel assembly positioned in a reactor core having an upper core support plate, the nuclear fuel assembly including an upper tie plate, comprising a rod disposed between the upper tie plate and upper core support plate and positioned at a proximate end in an aperture formed into a top of the upper tie plate and a distal end of the rod extending into contact with the upper core support plate for compressing the distal end further into the aperture due to the movement of the fuel assembly against the upper core support plate as a result of radiation induced growth. 9. The radiation induced growth indication apparatus as in  claim 8  wherein the aperture in the top of the upper tie plate extends into the upper tie plate a predetermined depth to allow the rod to be pressed into the aperture a distance corresponding to the movement of the fuel assembly toward the upper core support plate as a result of radiation induced growth. claim 8 10. A system comprising: a reactor core having an upper core support plate;  a pressurized water reactor nuclear fuel assembly positioned in said reactor core and having an upper tie plate; and  an inelastically compressible structural member disposed between and in contact with the upper tie plate and upper core support plate, wherein said compressible structural member is configured to be compressed due to a movement of the upper tie plate relative to the upper core support plate as a result of radiation-induced growth of the fuel assembly. 11. The system as in  claim 10  wherein the inelastically compressible structural member is a hollow tube. claim 10 12. The system as in  claim 2  wherein the hollow tube compresses in response to the application of a compressible force of 10 pounds or less. claim 2 13. The system as in  claim 3  wherein the hollow tube has a circumference and further comprises a plurality of holes through the circumference. claim 3