Patent Number: 
Section: claims

1. A device configured to control an intensity of a transmission of radiation from a source at a first location on a first side of the device to a second location on a second side of the device, the device comprising:a fluid reservoir;a Magneto-Rheological fluid comprising magnetically conductive particles that reflect neutrons, the Magneto-Rheological fluid occupying at least a portion of an interior of the fluid reservoir;a magnetic field generator for establishing a magnetic field across the Magneto-Rheological fluid; anda control system for controlling the magnetic field generator to vary the magnetic field across the Magneto-Rheological fluid to change an albedo of the device in accordance with a demand signal. 2. The device of claim 1 wherein the device is a nuclear reflector supported around at least a portion of a circumference of a core of a nuclear reactor, the nuclear reflector having at least a first state and a second state wherein a strength of the magnetic field is varied by the control system to change the nuclear reflector between the first and second states to change the albedo of the device. 3. The device of claim 2 wherein the magnetic field is established substantially parallel to an axial direction of the core of the nuclear reactor. 4. The device of claim 2 wherein the magnetic field is a plurality of discrete magnetic fields spaced around a circumference of the core of the nuclear reactor. 5. The device of claim 4 wherein the plurality of discrete magnetic fields are respectively established by a plurality of independently operated electromagnets. 6. The device of claim 1 including a monitoring system connected to the control system, configured to monitor the radiation on the first side of the device and generate and communicate the demand signal to the control system to adjust the magnetic field to control a level of the radiation on the first side of the device to a preselected level. 7. The device of claim 2 wherein the demand signal is a power demand signal of the nuclear reactor. 8. The device of claim 2 wherein the demand signal controls a level of the nuclear reactions within the core of the nuclear reactor by changing the magnetic field. 9. The device of claim 8 wherein the change in the magnetic field is the primary mechanism for controlling the nuclear reactions within the core during normal operation of the nuclear reactor. 10. The device of claim 2 wherein if power is lost to the magnetic field generator the Magneto-Rheological fluid transitions to a state that shuts down the reactor. 11. The device of claim 2 wherein the device alters the radial power distribution of the core. 12. The device of claim 2 wherein the device alters the axial power distribution of the core.