1. An apparatus comprising:
a fuel assembly including:
a plurality of fuel rods comprising fissile material;
a plurality of guide tubes interspersed amongst the fuel rods,
an upper end fitting connected with upper ends of guide tubes,
a lower end fitting,
end plugs connected with the lower ends of the guide tubes and having threaded male shafts extending from the lower ends of the guide tubes and passing through openings of the lower end fitting, and
female lock nuts threaded onto the threaded male shafts of the end plugs and locked with the lower end fitting to secure the lower end fitting to the lower ends of the guide tubes.
2. The apparatus of claim 1, further comprising:
dashpot tubes disposed in the lower ends of the guide tubes and connected to the end plugs, the female lock nuts not engaging the dashpot tubes.
3. The apparatus of claim 1, wherein the female lock nuts have swaged locking portions engaging recesses of the lower end fitting.
4. The apparatus of claim 1, wherein the female lock nuts have locking portions outwardly deformed into recesses of the lower end fitting.
5. The apparatus of claim 4, wherein the locking portions comprise portions of outboard annular walls of the female lock nuts that are outwardly deformed into recesses of the lower end fitting.
6. The apparatus of claim 5, wherein the locking portions comprise two locking portions of outboard annular walls of the female lock nuts that are outwardly deformed into recesses of the lower end fitting.
7. The apparatus of claim 4, wherein the locking portions comprise N locking portions arranged with N-fold symmetry around the female lock nut that are outwardly deformed into recesses of the lower end fitting.
8. The apparatus of claim 1, wherein the end plugs are welded to the lower ends of the guide tubes.
9. The apparatus of claim 1, further comprising:
a tool configured to rotate a female lock nut to thread it onto a threaded male shaft of an end plug connected with the lower end of a guide tube and to swage the female lock nut to form swaged locking portions of the lock nut that engage recesses of the lower end fitting to lock the lock nut with the lower end fitting.
10. The apparatus of claim 1, further comprising:
a pressure vessel containing a reactor core comprising an array of said fuel assemblies.
11. An apparatus comprising:
an end plug configured to connect with the lower end of a guide tube of a nuclear reactor fuel assembly, the end plug having a threaded male shaft that extends away from the lower end of the guide tube when the end plug is connected with the lower end of the guide tube, the threaded male shaft being sized to pass through an opening of a nuclear reactor fuel assembly lower end fitting; and
a female lock nut configured to thread onto the threaded male shaft of the end plug, the female lock nut having a deformable side wall configured to be swaged into a recess of the nuclear reactor fuel assembly lower end fitting to lock the female lock nut with the nuclear reactor fuel assembly lower end fitting.
12. The apparatus of claim 11, further comprising:
a tool configured to rotate a female lock nut to thread it onto the threaded male shaft of an end plug connected with the lower end of a guide tube and to swage the female lock nut to form the swaged locking portions engaging recesses of the nuclear reactor fuel assembly lower end fitting .
13. The apparatus of claim 12, wherein the tool is configured to connect with a torque wrench.
14. The apparatus of claim 11, wherein the deformable side wall of the female lock nut comprises an annular deformable sidewall that is outwardly deformable into one or more recesses of the nuclear reactor fuel assembly lower end fitting to lock the female lock nut with the nuclear reactor fuel assembly lower end fitting.
15. The apparatus of claim 11, wherein the deformable side wall is configured to be swaged into N recesses of the nuclear reactor fuel assembly lower end fitting having N-fold rotational symmetry around the female lock nut to lock the female lock nut with the nuclear reactor fuel assembly lower end fitting.
16. A method comprising:
inserting a threaded male shaft of an end plug connected with the lower end of a guide tube of a nuclear reactor fuel assembly through an opening of a nuclear reactor fuel assembly lower end fitting;
installing a female lock nut onto the inserted threaded male shaft of the end plug by rotating the female lock nut in a tightening direction to secure the nuclear reactor fuel assembly lower end fitting to the lower end of the guide tube; and
deforming a locking portion of the female lock nut into a recess of the nuclear reactor fuel assembly lower end fitting to lock the female lock nut with the nuclear reactor fuel assembly lower end fitting.
17. The method of claim 16, further comprising:
connecting the end plug to the lower end of the guide tube.
18. The method of claim 17, wherein the connecting comprises:
welding the end plug to the lower end of the guide tube.
19. The method of claim 17, further comprising:
connecting a dashpot tube to the end plug; and
inserting the dashpot tube into the end plug.
20. The method of claim 16, further comprising:
after the deforming, removing the female lock nut from the threaded male shaft by rotating the female lock nut in a loosening direction using rotational force sufficient to break the lock with the nuclear reactor fuel assembly lower end fitting provided by the deformed locking portion.
21. The method of claim 16, further comprising:
installing the nuclear reactor fuel assembly lower end fitting on the lower end of a fuel assembly frame including a plurality of guide tubes by performing the inserting, installing, and deforming for each guide tube of the fuel assembly frame; and
loading fuel rods comprising fissile material into the fuel assembly frame with the installed nuclear reactor fuel assembly lower end fitting.
22. The method of claim 21, further comprising:
after the installing and loading, unloading the fuel rods except for a broken fuel rod from the fuel assembly frame;
removing the nuclear reactor fuel assembly lower end fitting from the lower end of the fuel assembly frame by removing the female lock nuts from the threaded male shafts by rotating the female lock nuts in a loosening direction using rotational force sufficient to break the locks provided by the deformed locking portions of the female lock nuts; and
with the nuclear reactor fuel assembly lower end fitting removed, extracting a lower portion of the broken fuel rod from the fuel assembly frame via the lower end of the fuel assembly frame.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A communication device, comprising:
a ground element; and
an antenna element, disposed adjacent to an edge of the ground element, wherein the antenna element has a projection on the edge, the projection has a predetermined length, and the antenna element comprises:
a radiation element, having a first end and a second end, wherein the second end is open, and the radiation element has a plurality of bends, such that the second end is adjacent to the first end;
a feeding element, having a third end and a fourth end, wherein the third end is coupled through a capacitive element to a connection point on the radiation element, the connection point is positioned at or adjacent to the first end, the fourth end is coupled to a signal source, the feeding element comprises a first segment, the first segment is substantially parallel to the edge, and a length of the first segment is at least 0.2 times the predetermined length; and
a shorting element, having a fifth end and a sixth end, wherein the fifth end is coupled to a shorting point on the radiation element, the shorting point is adjacent to the connection point, the sixth end is coupled to the ground element, the shorting element comprises a second segment, the second segment is substantially parallel to the edge, and a length of the second segment is at least 0.2 times the predetermined length.
2. The communication device as claimed in claim 1, wherein the radiation element further comprises a first inductive element, the first inductive element is predetermined position and the first end is longer than 0.2 times the predetermined length, and the shorting point is positioned between the connection point and the predetermined position.
3. The communication device as claimed in claim 1, wherein the radiation element substantially has an inverted U-shape, or substantially extends to surround a rectangular region.
4. The communication device as claimed in claim 3, wherein the second segment is disposed between the first segment and the radiation element.
5. The communication device as claimed in claim 1, wherein the feeding element is further coupled through a second inductive element to the signal source.
6. The communication device as claimed in claim 2, wherein the antenna element at least operates in a first band and a second band, and frequencies of the first band are lower than frequencies of the second band.
7. The communication device as claimed in claim 6, wherein the radiation element is excited to generate a first resonant mode in the first band and at least a second resonant mode in the second band.
8. The communication device as claimed in claim 7, wherein the predetermined position is at or adjacent to a surface current null of the second resonant mode.
9. The communication device as claimed in claim 6, wherein the antenna element has a loop resonant path formed between the feeding element and the shorting element, the loop resonant path is excited to generate a third resonant mode in the second band, and the third resonant mode is arranged to increase bandwidth of the second band.
10. The communication device as claimed in claim 6, wherein the capacitive element causes excitation of the antenna element to further generate a fourth resonant mode in the first band, and the fourth resonant mode is arranged to increase bandwidth of the first band.