Patent Number: 
Section: claims

1. A system for positioning handling structures with articles for handling, the system comprising:a handling structure moveable over an area bounded by a boundary structure and populated by at least one article, wherein the handling structure is configured to move the article;a first emitter rigidly attached to the handling structure configured to emit visible light forming a first plane; anda second emitter rigidly attached to the handling structure configured to emit visible light forming a second plane, wherein an intersection of the first plane and the second plane forms a line extending directly from the area axially upward toward the handling structure, wherein an intersection of the first plane and the boundary structure creates a first visible intersection point horizontally aligned with the handling structure, and wherein an intersection of the second plane and the boundary structure creates a second visible intersection point vertically aligned with the handling structure. 2. The system of claim 1, further comprising:a sensor configured to detect at least one of, the intersection of the first plane and the second plane, and the first and the second intersection points; anda computer processor configured to determine a position of the handling structure from the at least one of, the intersection of the first plane and the second plane, and the first and the second intersection points. 3. The system of claim 2, further comprising:a controller configured to move the handling structure over the area and raise and lower the handling structure to move the article, wherein the computer processor is further configured to control the controller to move the handling structure based on the determined position. 4. The system of claim 3, wherein the computer processor is further configured to control the controller to move the handling structure based on a list of positions versus articles. 5. The system of claim 4, further comprising:the area, wherein the area is a nuclear reactor core; andthe article, wherein the article is a nuclear fuel assembly, and wherein the handling structure is a refueling bridge including an axially extensible mast that moves the nuclear fuel assembly. 6. A system for determining position of fuel handling structures in a nuclear reactor environment, the system comprising:a fuel handling structure moveable over a volume populated by nuclear fuel;an emitter system rigidly attached to the handling structure, wherein the emitter system emits, a first visible plane of light axially downward and horizontally to visibly intersect a boundary structure of the volume at a first point and a nuclear fuel assembly of the nuclear fuel, and a second visible plane of light axially downward and vertically to visibly intersect the boundary structure at a second point and the nuclear fuel assembly, wherein the first visible plane of light and the second visible plane of light intersect each other only on a line extending axially upward from the nuclear fuel assembly to the fuel handling structure. 7. The system of claim 6, wherein the emitter system is rigidly attached to a refueling bridge, a trolley on the refueling bridge, a mast extending axially from the trolley, or a grapple extending axially from the mast. 8. The system of claim 7, wherein the volume is a nuclear fuel core in a nuclear reactor, and wherein the boundary structure is at an outermost periphery of the core. 9. The system of claim 8, wherein the emitter system configured to operate underwater in reactor coolant water emit light visible after passing through at least twenty-five feet of the coolant water. 10. The system of claim 8, wherein the first and the second planes of light are formed by lasers. 11. The system of claim 6, further comprising:a sensor configured to detect the first point and the second point; anda computer processor configured to determine a position of the fuel handling structure from the first and the second points. 12. The system of claim 11, further comprising:a controller configured to move the fuel handling structure over the volume and raise and lower the fuel handling structure with respect to the volume, wherein the computer processor is further configured to control the controller to move the fuel handling structure based on the determined position. 13. The system of claim 12, wherein the computer processor is further configured to control the controller to move the handling structure based on a list of core positions versus fuel assemblies. 14. The system of claim 6, wherein the emitter system includes an offset emitter, wherein the fuel handling structure includes a mast extending axially from a refueling bridge, and wherein the offset emitter is mounted on the refueling bridge. 15. The system of claim 14wherein the offset emitter is a different color and separately operable from other emitters of the emitter system. 16. The system of claim 14wherein the offset emitter is configured to emit the first plane of light. 17. The system of claim 16, wherein the first plane of light is at an angle to the axial direction, and wherein the second plane of light is only in the axial direction.