Patent Number: 
Section: claims

1. A detection apparatus usable with a fuel rod from among a plurality of fuel rods of a fuel assembly, the fuel rod having a cladding that has an interior region, the fuel rod being situated within a nuclear reactor, the detection apparatus being cooperable with an electronic processing apparatus situated outside of the reactor, the detection apparatus comprising:a transmitter that is structured to be positioned outside the cladding and inside the nuclear reactor in the vicinity of the fuel rod and structured to generate an excitation pulse and to transmit the excitation pulse through the cladding and into the interior region;an electrical circuit apparatus having a resonant electrical circuit that is structured to be supported within the interior region and to generate a response pulse in response to the excitation pulse and to transmit the response pulse in the form of a magnetic field signal that is structured to travel from the interior region and through the cladding;the resonant electrical circuit comprising a plurality of circuit components, at least one circuit component of the plurality of circuit components having a property which is structured to vary in response to a condition of the fuel rod and which, responsive to a change in the condition, is structured to cause the property and the response pulse to vary with the change in the condition and to be indicative of the condition; anda receiver structured to be supported within the nuclear reactor outside the cladding and in the vicinity of the fuel rod, the receiver being structured to receive the response pulse and to communicate to the electronic processing apparatus an output responsive to the response pulse. 2. The detection apparatus of claim 1 wherein the plurality of circuit components comprise an inductor having a coil, the inductor having a inductance which is structured to vary in response to the condition of the fuel rod and which, responsive to the change in the condition, is structured to cause the response pulse to have a frequency that varies with the condition. 3. The detection apparatus of claim 2 wherein the fuel rod has a number of fuel pellets situated within the interior region, wherein the condition is a center-line fuel pellet temperature of the fuel rod, and wherein the electrical circuit apparatus further comprises a temperature transmission apparatus comprising an element that is elongated and that is formed at least in part of a ferromagnetic material, at least a portion of the element being receivable in the coil, the at least portion of the element that is receivable in the coil varying with the condition to cause the inductance to vary in response to the change in the condition. 4. The detection apparatus of claim 3 wherein the element has an element temperature that varies with the center-line fuel pellet temperature, the element having a permeability that is structured to vary in response to the element temperature and which, responsive to a change in the center-line fuel pellet temperature, is structured to undergo a change in its permeability to alter the inductance and to resultantly cause the response pulse to have a frequency that varies with the center-line fuel pellet temperature. 5. The detection apparatus of claim 3 wherein the number of fuel pellets are structured to undergo thermal expansion as a function of an increase in the center-line fuel pellet temperature, the element being structured to be moved relative to the coil by the number of fuel pellets undergoing thermal expansion to thereby cause the inductance to vary in response to the change in the condition. 6. The detection apparatus of claim 5 wherein the temperature transmission apparatus further comprises a support engaged with a fuel pellet of the number of fuel pellets, the element being engaged with the support. 7. The detection apparatus of claim 2 wherein the condition is an ambient pressure within the interior region, and wherein the electrical circuit apparatus further comprises a pressure indication apparatus comprising an element that is elongated and that is formed at least in part of a ferromagnetic material, at least a portion of the element being receivable in the coil, the at least portion of the element that is receivable in the coil varying with the condition to cause the inductance to vary in response to the change in the condition. 8. The detection apparatus of claim 7 wherein the pressure indication apparatus further comprises a vessel having a hollow cavity that is sealed to resist fluid communication with the interior region, the vessel being structured to be supported within the interior region and being structured to undergo contraction in response to an increase in the ambient pressure within the interior region, the element being situated on the vessel being structured to be moved relative to the coil by the vessel undergoing contraction to thereby cause the inductance to vary in response to the change in the condition. 9. The detection apparatus of claim 8 wherein the vessel is a Bourdon tube that is one of a spiral shape and a helical shape. 10. The detection apparatus of claim 7 wherein the pressure indication apparatus further comprises a vessel and a seal, the vessel having a hollow cavity, the seal dividing the interior region into a main portion and a sub-region, the vessel being supported within the sub-region, the main portion being structured to experience the change in ambient pressure, the seal permitting fluid communication between the main portion and the cavity while resisting fluid communication between the main portion and the sub-region, the vessel being structured to undergo expansion and contraction in response to an increase and a decrease, respectively, in the ambient pressure within the main portion, the element being situated on the vessel being structured to be moved relative to the coil by the vessel undergoing expansion and contraction to thereby cause the inductance to vary in response to the change in the condition. 11. The detection apparatus of claim 10 wherein the vessel is one of a bellows having a number of corrugations formed therein and a Bourdon tube that is one of a spiral shape and a helical shape. 12. The detection apparatus of claim 7 wherein the pressure indication apparatus further comprises a vessel having a hollow cavity that is in fluid communication with the interior region, the vessel being structured to be supported within the interior region and being structured to undergo expansion in response to an increase in the ambient pressure within the interior region, the element being situated on the vessel being structured to be moved relative to the coil by the vessel undergoing expansion to thereby cause the inductance to vary in response to the change in the condition. 13. The detection apparatus of claim 1 wherein the resonant electrical circuit comprises a plurality of circuit components that comprise a capacitor, the capacitor having a capacitance which is structured to vary in response to the condition of the fuel rod and which, responsive to a change in the condition, is structured to cause the response pulse to have a frequency that varies with the condition. 14. The detection apparatus of claim 13 wherein the capacitor comprises a dielectric material that is structured to absorb fission gases that are generated within the interior region, the dielectric material having a dielectric value that is structured to vary in response to its absorption of fission gases and which, responsive to a change in an ambient pressure within the interior region, is structured to undergo a change in its absorption of fission gases to alter the capacitance and to resultantly cause the response pulse to have a frequency that varies with the ambient pressure. 15. The detection apparatus of claim 4 wherein the temperature transmission apparatus further has another element that is elongated and that is formed of a refractory metal, the another element being engaged with a fuel pellet of the fuel rod, the element being engaged with the another element, the another element being structured to conduct heat between the fuel pellet and the element. 16. The detection apparatus of claim 15 wherein the fuel pellet has a receptacle formed therein, the another element being received in the receptacle. 17. A method of detecting a condition of a fuel rod from among a plurality of fuel rods of a fuel assembly, the fuel rod having a cladding that has an interior region, the fuel rod being situated within a nuclear reactor, the method comprising:employing a detection apparatus to detect the condition, the detection apparatus being cooperable with an electronic processing apparatus situated outside of the nuclear reactor, the detection apparatus having a transmitter that is structured to be positioned outside the cladding and inside the nuclear reactor in the vicinity of the fuel rod, an electrical circuit apparatus having a resonant electrical circuit that is structured to be supported within the interior region, the resonant electrical circuit comprising a plurality of circuit components, at least one circuit component of the plurality of circuit components having a property which is structured to vary in response to a condition of the fuel rod and which, responsive to a change in the condition, is structured to cause the property and the response pulse to vary with the change in the condition and to be indicative of the condition, and a receiver structured to be supported within the nuclear reactor outside the cladding and in the vicinity of the fuel rod;the employing comprising:generating with the transmitter an excitation pulse and transmitting the excitation pulse through the cladding and into the interior region;generating with the resonant electrical circuit a response pulse in response to the excitation pulse and transmitting the response pulse in the form of a magnetic field signal from the interior region and through the cladding; andreceiving on the receiver the response pulse and communicating to the electronic processing apparatus an output responsive to the response pulse. 18. The method of claim 17, wherein the resonant electrical circuit comprises a plurality of circuit components that comprise a capacitor having a capacitance, and further comprising varying the capacitance in response to the condition of the fuel rod to cause the response pulse to have a frequency that varies with the condition. 19. The method of claim 17, wherein the resonant electrical circuit comprises a plurality of circuit components that comprise an inductor having an inductance, and further comprising varying the inductance in response to the condition of the fuel rod to cause the response pulse to have a frequency that varies with the condition.