Patent Number: 
Section: claims

1. A spent nuclear fuel pool emergency cooling system comprising:an evaporator/heat exchanger having an internal fluid path that extends in a generally planar direction, the evaporator/heat exchanger being supported substantially vertically from a wall of a spent fuel pool;a hinged support connecting a first side portion of the evaporator/heat exchanger to the wall of the spent fuel pool, the hinged support configured to rotate the evaporator/heat exchanger away from the wall and outward into a coolant within the spent fuel pool with a second side portion of the evaporator/heat exchanger, which is opposed from the first side portion, laterally spaced from the wall of the spent fuel pool;a fusible link actuator that connects the wall and the second side portion of the evaporator/heat exchanger to maintain the evaporator/heat exchanger in the substantially vertical position, the fusible link actuator being responsive to a preselected change in an element of an environment of the spent fuel pool, to a pre-established level, to transfer the evaporator/heat exchanger to a position wherein the second side portion of the evaporator/heat exchanger is laterally spaced from the wall of the spent fuel pool;a supply of a cryogenic fluid fluidly connected to the internal fluid path;a cryogenic storage vessel for storing the supply of the cryogenic fluid; anda passively actuated valve for preventing the flow of the cryogenic fluid from the cryogenic storage vessel to the internal fluid path until the second side portion of the evaporator/heat exchanger is laterally spaced by a preselected extent from the wall of the spent fuel pool. 2. The spent nuclear fuel pool emergency cooling system of claim 1 wherein the position wherein the second side portion of the evaporator/heat exchanger is laterally spaced from the wall of the spent fuel pool places the evaporator/heat exchanger in a substantially horizontal position, to insure the evaporator/heat exchanger is submerged in the coolant of the spent fuel pool. 3. The spent nuclear fuel pool emergency cooling system of claim 1 wherein when the second side portion of the evaporator/heat exchanger is laterally spaced by the preselected extent from the wall of the spent fuel pool, the passively actuated valve opens to expand the cryogenic fluid through the internal fluid path wherein the cryogenic fluid captures heat and exits the internal fluid path as a pressurized gas. 4. The spent nuclear fuel pool emergency cooling system of claim 3 wherein the pressurized gas is connected to a gas driven mechanical pump. 5. The spent nuclear fuel pool emergency cooling system of claim 4 wherein the gas driven mechanical pump supplies makeup water to the spent fuel pool. 6. The spent nuclear fuel pool emergency cooling system of claim 4 wherein the gas driven mechanical pump is an air operated double diaphragm pump. 7. The spent nuclear fuel pool emergency cooling system of claim 6 wherein the air operated double diaphragm pump is connected to a pulse dampener. 8. The spent nuclear fuel pool emergency cooling system of claim 3 wherein the pressurized gas is connected to a compressed gas turbo generator. 9. The spent nuclear fuel pool emergency cooling system of claim 8 wherein the compressed gas turbo generator drives an air cooling system. 10. The spent nuclear fuel pool emergency cooling system of claim 8 wherein the compressed gas turbo generator provides power to an electrical pump. 11. The spent nuclear fuel pool emergency cooling system of claim 10 wherein the electrical pump supplies make-up water to the spent fuel pool. 12. The spent nuclear fuel pool emergency cooling system of claim 9 wherein the pressurized gas exiting the internal fluid path is conducted through a gas to air heat exchanger after driving the compressed gas turbo generator. 13. The spent nuclear fuel pool emergency cooling system of claim 3 including a check valve in fluid communication with an inlet to the evaporator/heat exchanger to prevent the pressurized gas from flowing back into the cryogenic storage vessel. 14. The spent nuclear fuel pool emergency cooling system of claim 3 wherein the internal fluid path is in fluid communication with a pressure regulating valve to control pressure of the gas in the internal fluid path. 15. The spent nuclear fuel pool emergency cooling system of claim 1 wherein aside from the evaporator/heat exchanger, a plurality of components and instrumentation necessary for implementing the emergency cooling system can be supported on a transportable skid that can be back fitted into existing nuclear power plants. 16. The spent nuclear fuel pool emergency cooling system of claim 1 wherein the evaporator/heat exchanger has an inlet and an outlet to the internal fluid path and the internal fluid path extends in a serpentine pattern between the inlet and the outlet. 17. The spent nuclear fuel pool emergency cooling system of claim 1 wherein the internal fluid path extends substantially through a single plane. 18. The spent nuclear fuel pool emergency cooling system of claim 1 wherein the evaporator/heat exchanger is supported substantially vertically upward from the wall of the spent fuel pool. 19. The spent nuclear fuel pool emergency cooling system of claim 1 wherein the cryogenic fluid is nitrogen or mixtures of nitrogen. 20. The spent nuclear fuel pool emergency cooling system of claim 3 wherein the pressurized gas is air.