Patent Number: 
Section: claims

1. A nuclear fission reactor, comprising:a reactor vessel;a nuclear fission fuel element received in the reactor vessel and capable of generating a gaseous fission product;a valve body associated with said nuclear fission fuel element, said valve body defining a plenum therein for receiving the gaseous fission product; anda valve in operative communication with the plenum for controllably venting the gaseous fission product from the plenum, wherein said valve body comprises a flexible diaphragm coupled to said valve for moving said valve to a closed position. 2. The nuclear fission reactor of claim 1, further comprising:a cap mounted on said valve; anda manipulator extendable to said cap for manipulating said cap. 3. The nuclear fission reactor of claim 1, further comprising a manipulator extendable to said valve for manipulating said valve. 4. The nuclear fission reactor of claim 1, further comprising:an articulated manipulator arm extendable to the plenum; anda receptacle carried by said articulated manipulator arm and engageable with the plenum for receiving the gaseous fission product controllably vented from the plenum. 5. The nuclear fission reactor of claim 1, wherein said valve is responsive to a parameter chosen from a pressure in the plenum and a type of gaseous fission product in the plenum. 6. The nuclear fission reactor of claim 1, further comprising a sensor in operative communication with the plenum. 7. The nuclear fission reactor of claim 6, wherein said sensor senses a parameter chosen from pressure, a type of gaseous fission product, and a radioactive fission product. 8. The nuclear fission reactor of claim 6, wherein said sensor comprises a sensor chosen from a radiation sensor, a chemical sensor, and an optical sensor. 9. The nuclear fission reactor of claim 6, wherein said sensor comprises a transmitter. 10. The nuclear fission reactor of claim 9, wherein said transmitter is configured to transmit an identification signal identifying said valve body. 11. The nuclear fission reactor of claim 1, further comprising a reactor core chosen from a thermal neutron reactor core, a fast neutron reactor core, a fast neutron breeder reactor core, and a traveling wave fast neutron reactor core. 12. The nuclear fission reactor of claim 1, further comprising a canister surrounding said fuel element. 13. The nuclear fission reactor of claim 12,wherein said canister has a bottom portion defining a first opening; andwherein said canister has a side portion defining a second opening. 14. The nuclear fission reactor of claim 13, wherein said canister comprises a tube sheet therein having a contour shaped for guiding a coolant along a coolant flow path extending from the first opening and through the second opening. 15. The nuclear fission reactor of claim 13, wherein said canister comprises a ceramic tube sheet therein for dissipating heat and having a contour shaped for guiding a coolant along a coolant flow path extending from the first opening and through the second opening. 16. The nuclear fission reactor of claim 1, further comprising a reservoir coupled to said valve for receiving the gaseous fission product vented by said valve. 17. The nuclear fission reactor of claim 16, wherein said reservoir comprises a filter for separating a condensed phase fission product from the gaseous fission product. 18. The nuclear fission reactor of claim 17, wherein said filter comprises a filter chosen from a HEPA filter, a semi-permeable membrane, an electrostatic collector, and a cold trap. 19. The nuclear fission reactor of claim 16,wherein said reservoir is capable of being coupled to the reactor vessel; andwherein said reservoir is capable of being decoupled from the reactor vessel for removing the gaseous fission product from the reactor vessel. 20. The nuclear fission reactor of claim 16,wherein said reservoir is capable of being coupled to the reactor vessel; andwherein said reservoir is capable of remaining coupled to the reactor vessel for storing the gaseous fission product at the reactor vessel. 21. The nuclear fission reactor of claim 1, further comprising a coolant system in operational communication with said valve for receiving the gaseous fission product controllably vented by said valve. 22. The nuclear fission reactor of claim 21, further comprising a removal system in operational communication with said coolant system for removing the gaseous fission product from said coolant system. 23. The nuclear fission reactor of claim 1, wherein said valve is reclosable. 24. The nuclear fission reactor of claim 1, wherein said valve is sealably reclosable. 25. The nuclear fission reactor of claim 1, further comprising a controller coupled to said valve for controlling operation of said valve. 26. A nuclear fission reactor, comprising:a reactor vessel;a plurality of nuclear fission fuel element bundles received in the reactor vessel and capable of generating a gaseous fission product;a plurality of valve bodies associated with respective ones of said plurality of nuclear fission fuel element bundles, at least one of said plurality of valve bodies defining a plenum therein for receiving the gaseous fission product;a valve disposed in the at least one of said plurality of valve bodies and in communication with the plenum for controllably venting the gaseous fission product from the plenum;a flexible diaphragm coupled to said valve for moving said valve; anda removable cap threadably mounted on said valve. 27. The nuclear fission reactor of claim 26, wherein said flexible diaphragm is capable of moving said valve to a closed position. 28. The nuclear fission reactor of claim 26, further comprising an articulated manipulator arm extendable to said cap for threadably dismounting said cap from said valve. 29. The nuclear fission reactor of claim 26, further comprising an articulated manipulator arm extendable to said valve for operating said valve. 30. The nuclear fission reactor of claim 26, further comprising:an articulated manipulator arm extendable to the plenum; anda receptacle carried by said articulated manipulator arm and engageable with the plenum for receiving the gaseous fission product controllably vented from the plenum. 31. The nuclear fission reactor of claim 26, wherein said valve is responsive to a parameter chosen from pressure in the plenum and a type of gaseous fission product in the plenum. 32. The nuclear fission reactor of claim 26, further comprising a sensor in operative communication with the plenum. 33. The nuclear fission reactor of claim 32, wherein said sensor senses a parameter chosen from pressure in the plenum, a type of gaseous fission product in the plenum, and a radioactive fission product in the plenum. 34. The nuclear fission reactor of claim 32, wherein said sensor comprises sensor chosen from a radiation sensor, a chemical sensor, and an optical sensor. 35. The nuclear fission reactor of claim 32, wherein said sensor comprises a transmitter. 36. The nuclear fission reactor of claim 35, wherein said transmitter is configured to transmit an identification signal identifying said valve body. 37. The nuclear fission reactor of claim 26, further comprising a nuclear reactor core chosen from a thermal neutron reactor core, a fast neutron reactor core, a fast neutron breeder reactor core, and a traveling wave fast neutron reactor core. 38. The nuclear fission reactor of claim 26, further comprising a canister surrounding at least one of said plurality of nuclear fission fuel element bundles. 39. The nuclear fission reactor of claim 38,wherein said canister has a bottom portion defining a flow opening; andwherein said canister has a side portion defining a flow port. 40. The nuclear fission reactor of claim 39, wherein said canister comprises a tube sheet therein having a contour on an underside surface thereof shaped for guiding a coolant along a curved coolant flow path extending from the flow opening and through the flow port. 41. The nuclear fission reactor of claim 39, wherein said canister comprises a ceramic tube sheet therein for dissipating heat and having a contour on an underside surface thereof shaped for guiding a coolant along a curved coolant flow path extending from the flow opening and through the flow port. 42. The nuclear fission reactor of claim 26, further comprising a reservoir coupled to said valve for receiving the gaseous fission product vented by said valve. 43. The nuclear fission reactor of claim 42, wherein said reservoir comprises a removable filter for separating and capturing a condensed phase fission product from the gaseous fission product. 44. The nuclear fission reactor of claim 43, wherein said filter comprises a filter chosen from a HEPA filter, a semi-permeable membrane, an electrostatic collector, and a cold trap. 45. The nuclear fission reactor of claim 42,wherein said reservoir is coupled to the reactor vessel; andwherein said reservoir is capable of being decoupled from the reactor vessel for removing the gaseous fission product from the reactor vessel. 46. The nuclear fission reactor of claim 42,wherein said reservoir is coupled to the reactor vessel; andwherein said reservoir is capable of remaining coupled to the reactor vessel for storing the gaseous fission product at the reactor vessel. 47. The nuclear fission reactor of claim 26, further comprising a coolant system in operational communication with said valve for receiving the gaseous fission product controllably vented by said valve. 48. The nuclear fission reactor of claim 47, further comprising a removal system in operational communication with said coolant system for removing the gaseous fission product from said coolant system. 49. The nuclear fission reactor of claim 26, wherein said valve is reclosable. 50. The nuclear fission reactor of claim 26, wherein said valve is sealably reclosable. 51. The nuclear fission reactor of claim 26, wherein said valve is operable to controllably vent the gaseous fission product according to a predetermined release rate for minimizing size of an associated gaseous fission product clean-up system. 52. The nuclear fission reactor of claim 26, further comprising a controller coupled to said valve for controlling operation of said valve.