Patent Number: 
Section: claims

1. A damping device for use when immersed in liquid coolant in an operating nuclear reactor, the device comprising:a piston configured to attach to a first component immersed in liquid coolant in the operating nuclear reactor, the piston including at least one fluid passage;a housing capturing the piston and configured to attach to a second component immersed in liquid coolant in the operating nuclear reactor, the piston and the housing fabricated of a material substantially maintaining its physical properties in the operating nuclear reactor, the housing being divided into first and second fluid chambers by a head of the piston, the head of the piston being flush with the housing about an outer circumference of the head of the piston; anda damping fluid in the housing damping movement between the piston and housing and flowing through the at least one fluid passage, the damping fluid being chemically compatible with the coolant fluid in the operating nuclear reactor. 2. The damping device of claim 1, further comprising:at least one spring within the housing, the at least one spring connected between the piston and the housing so as to damp movement between the piston and the housing. 3. The damping device of claim 1, further comprising:a first spring in the first fluid chamber within the housing; anda second spring in the second fluid chamber within the housing, the first and second springs connected between the piston and the housing so as to damp movement between the piston and the housing. 4. A damping device for use when immersed in liquid coolant in an operating nuclear reactor, the device comprising:a piston configured to attach to a first component immersed in liquid coolant in the operating nuclear reactor, the piston including at least one fluid passage, the piston including a shaft having a first mounting hole configured to directly attach to the first component;a housing capturing the piston and configured to attach to a second component immersed in liquid coolant in the operating nuclear reactor, the piston and the housing fabricated of a material substantially maintaining its physical properties in the operating nuclear reactor, the housing including a second mounting hole configured to directly attach to the second component at an end of the housing; anda damping fluid in the housing damping movement between the piston and housing and flowing through the at least one fluid passage, the damping fluid being chemically compatible with the coolant fluid in the operating nuclear reactor. 5. The damping device of claim 1, wherein the first component is a first jet pump inlet mixer and the second component is at least one of a restrainer bracket, a set screw, a second jet pump inlet mixer, and jet pump riser. 6. A method of damping vibration and relative movement between a first and a second component immersed in liquid coolant in a nuclear reactor during operation, the method comprising:attaching a piston to a first component in the nuclear reactor, the piston including at least one fluid passage, the piston including a shaft having a first mounting hole configured to directly attach to the first component; andattaching a housing to the second component in the nuclear reactor, the housing capturing the piston, the housing including a damping fluid damping movement between the piston and housing and flowing through the at least one fluid passage, the damping fluid being chemically compatible with the coolant fluid in the operating nuclear reactor, the piston and the housing fabricated of a material substantially maintaining its physical properties in the operating nuclear reactor, and the housing being divided into first and second fluid chambers by a head of the piston, the head of the piston being flush with the housing about an outer circumference of the head of the piston. 7. The method of claim 6, wherein the first component is a first jet pump inlet mixer and the second component is at least one of a restrainer bracket, a set screw, a second jet pump inlet mixer, and jet pump riser. 8. The clamping device of claim 1, wherein the damping fluid is a same fluid as the coolant fluid. 9. The clamping device of claim 1, wherein the damping fluid is demineralized water. 10. The clamping device of claim 1,wherein the head of the piston includes a plurality of fluid passages, each of the fluid passages passing through and defined only by the head of the piston,wherein the damping fluid is sealed within the housing and damps movement between the piston and housing by flowing only through the plurality of fluid passages, andwherein the piston includes a shaft that extends from inside the housing to outside the housing.