Patent Number: 
Section: claims

1. A thermo-acoustic nuclear power distribution measurement assembly comprising:a plurality of thermo-acoustic engines supported in a spaced tandem array and sized to fit within an instrument thimble in a nuclear fuel assembly along an axial length of the fuel assembly;wherein said plurality of thermo-acoustic engines include at least one pair of thermo-acoustic engines;wherein each thermo-acoustic engine of the plurality of thermo-acoustic engines includes an outer cladding, a self-sustaining heat source, a resonant chamber and a heat exchanger stack;wherein the cladding is sized to fit within the instrument thimble to enable coolant to flow around an outside surface of the cladding;wherein the cladding surrounds the heat source, the resonant chamber and the heat exchanger stack;wherein the cladding includes a cladding interior;wherein the cladding interior includes one end and another end;wherein the heat source is supported within the cladding interior at a first side of the heat exchanger stack facing the one end;wherein the resonant chamber is located within the cladding interior at a second side of the heat exchanger stack facing the another end;wherein the heat source is separated from the resonant chamber;wherein the heat exchanger stack is located within the cladding interior;wherein the heat exchanger stack separates the heat source from the resonant chamber;wherein each respective resonant chamber of the plurality of thermo-acoustic engines is configured to generate a sound having a frequency that differs from every other respective resonant chamber of the plurality of thermo-acoustic engines;wherein for each respective resonant chamber, the sound frequency generated by the respective resonant chamber allows that respective resonant chamber to be uniquely identified from the other respective resonant chambers of said plurality of thermo-acoustic engines;wherein for each respective resonant chamber, a difference in temperature between:a first location which is within the respective resonant chamber on the second side of the heat exchanger stack anda second location which is on the first side of the heat exchanger stack that is heated by the heat source,wherein the second side is opposite the first side; andcauses the respective resonant chamber to generate a sound with a frequency which comprises an amplitude,wherein the amplitude generated corresponds to the difference in temperature between the first location and the second location,wherein the amplitude generated also corresponds to a nuclear power level at an axial location of the respective resonant chamber;wherein a portion of the cladding that surrounds the resonant chamber is thermally conductive; anda spacer interposed between the thermo-acoustic engines of each pair of thermo-acoustic engines. 2. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein a portion of the cladding that surrounds the self-sustaining heat source is thermally insulated. 3. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein the spacers are configured to thermally insulate the heat source of a first engine of a pair of the thermo-acoustic engines from a second engine of the pair of thermo-acoustic engines. 4. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein the self-sustaining heat source of at least some of the plurality of thermo-acoustic engines is supported within a portion of a lower end of the cladding. 5. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 and further including an acoustic telemetry system, wherein the acoustic telemetry system is configured to have acoustic sensors receive at a location outside of a nuclear reactor vessel, sound generated by substantially each respective engine of the plurality of thermo-acoustic engines, when the thermo-acoustic nuclear power distribution measurement assembly is positioned within the nuclear reactor vessel during operation of a corresponding reactor power generation system. 6. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein the spaced tandem array of the plurality of thermo-acoustic engines is configured to substantially span a height of a nuclear fuel assembly instrument thimble. 7. The thermo-acoustic nuclear power distribution measurement assembly of claim 6 wherein the tandem array of the plurality of thermo-acoustic engines comprises seven thermo-acoustic engines. 8. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein the self-sustaining heat source comprises fissile material. 9. The thermo-acoustic nuclear power distribution measurement assembly of claim 1 wherein the self-sustaining heat source is formed from a material operable to convert fission gamma radiation into a quantity of heat that is able to cause the resonant chamber to generate the different frequency of sound with the amplitude. 10. The thermo-acoustic nuclear power distribution measurement assembly of claim 9 wherein the self-sustaining heat source comprises Tungsten. 11. A nuclear power generation system comprising:a nuclear reactor having a core;a plurality of nuclear fuel assemblies supported within the core, at least some of the fuel assemblies have an instrument thimble having an axial length that spans a height of the corresponding fuel assembly;a thermo-acoustic nuclear power distribution measurement assembly positioned within at least some of the instrument thimbles, the thermo-acoustic nuclear power distribution measurement assembly comprising:a plurality of thermo-acoustic engines supported in a spaced tandem array and sized to fit within an instrument thimble in a nuclear fuel assembly along the axial length;wherein said plurality of thermo-acoustic engines include at least one pair of thermo-acoustic engines;wherein each thermo-acoustic engine of the plurality of thermo-acoustic engines includes an outer cladding, a self-sustaining heat source, a resonant chamber and a heat exchanger stack;wherein the cladding is sized to fit within the instrument thimble to enable coolant to flow around an outside surface of the cladding;wherein the cladding surrounds the heat source, the resonant chamber and the heat exchanger stack;wherein the cladding includes a cladding interior;wherein the cladding interior includes one end and another end;wherein the heat source is supported within the cladding interior at the one end;wherein the resonant chamber is located within the cladding interior at the another end;wherein the heat source is separated from the resonant chamber;wherein the heat exchanger stack is located within the cladding interior;wherein the heat exchanger stack separates the heat source from the resonant chamber;wherein each respective resonant chamber of the plurality of thermo-acoustic engines is configured to generate a sound having a frequency that differs from every other respective resonant chamber of the plurality of thermo-acoustic engines;wherein for each respective resonant chamber, the sound frequency generated by the respective resonant chamber allows that respective resonant chamber to be uniquely identified from the other respective resonant chambers of said plurality of thermo-acoustic engines;wherein for each respective resonant chamber, a difference in temperature between:a first location which is within the respective resonant chamber on the second side of the heat exchanger stack, anda second location which is on the first side of the heat exchanger stack that is heated by the heat source,wherein the second side is opposite the first side; andcauses the respective resonant chamber to generate a sound with a frequency which comprises an amplitude;wherein the amplitude generated corresponds to the difference in temperature between the first location and the second location,wherein the amplitude generated also corresponds to a nuclear power level at an axial location of the respective resonant chamber;wherein a portion of the cladding that surrounds the resonant chamber is thermally conductive; anda spacer interposed between the thermo-acoustic engines of each pair of thermo-acoustic engines. 12. The nuclear power generation system of claim 11 wherein a portion of the cladding that surrounds the self-sustaining heat source is thermally insulated. 13. The nuclear power generation system of claim 11 wherein the spacers are configured to thermally insulate the heat source of a first engine of a pair of the thermo-acoustic engines from a second engine of the pair of thermo-acoustic engines. 14. The nuclear power generation system of claim 11 wherein the self-sustaining heat source of at least some of the plurality of thermo-acoustic engines is supported within a portion of a lower end of the cladding. 15. The nuclear power generation system of claim 11 and further including an acoustic telemetry system, wherein the acoustic telemetry system is configured to have acoustic sensors receive at a location outside of a nuclear reactor vessel, sound generated by substantially each respective engine of the plurality of thermo-acoustic engines, when the thermo-acoustic nuclear power distribution measurement assembly is positioned within the nuclear reactor vessel during operation of a corresponding reactor power generation system. 16. The nuclear power generation system of claim 11 wherein the spaced tandem array of the plurality of thermo-acoustic engines is configured to substantially span a height of a nuclear fuel assembly instrument thimble. 17. The nuclear power generation system of claim 16 wherein the tandem array of the plurality of thermo-acoustic engines comprises seven thermo-acoustic engines. 18. The nuclear power generation system of claim 11 wherein the nuclear reactor has a plurality of control rods that are configured to be inserted into and withdrawn out of at least some of the fuel assemblies and each of the fuel assemblies that does not receive a control rod has one of the thermo-acoustic nuclear power distribution measurement assemblies positioned within its instrument thimble. 19. The nuclear power generation system of claim 18 wherein one of the thermo-acoustic nuclear power distribution measurement assemblies is located in each of the instrument thimbles within the core. 20. The nuclear power generation system of claim 11 wherein the self-sustaining heat source comprises fissile material. 21. The nuclear power generation system of claim 11 wherein the self-sustaining heat source is formed from a material operable to convert fission gamma radiation into a quantity of heat that is able to cause the resonant chamber to generate the different frequency of sound with the amplitude. 22. The nuclear power generation system of claim 21 wherein the self-sustaining heat source comprises Tungsten.