Patent Number: 
Section: claims

1. A method of operating a nuclear fission reactor fuel assembly configured for controlled removal of a volatile fission product released by nuclear fission reactor, comprising:using an enclosure enclosing a porous nuclear fuel body having a fissile material and the volatile fission product therein; andusing a fluid control subassembly coupled to the enclosure to control removal of at least a portion of the volatile fission product from the porous nuclear fuel body at a plurality of locations of the nuclear fission reactor by circulating a fission product removal fluid through the porous nuclear fuel body using the fluid control subassembly, so that at least a portion of the volatile fission product is removed from the porous nuclear fuel body and the enclosure while retaining the fissile material in the enclosure while the fluid control subassembly circulates the fission product removal fluid through the porous nuclear fuel body in the enclosure. 2. The method according to claim 1, further comprising controlling operation of the fluid control subassembly by operating a control unit coupled to the fluid control subassembly. 3. The method according to claim 1, further comprising receiving the volatile fission product into a reservoir coupled to the fluid control subassembly. 4. The method according to claim 1, wherein circulating the fission product removal fluid includes circulating a fluid between the fluid control subassembly and the porous nuclear fuel body by operating a pump integrally connected to the fluid control subassembly. 5. The method according to claim 1, wherein circulating the fission product removal fluid includes controlling flow of a fluid between the enclosure and the fluid control subassembly by operating a valve interposed between the enclosure and the fluid control subassembly. 6. The method according to claim 1, wherein using the fluid control subassembly comprises operating a controllably breakable barrier. 7. The method according to claim 1, further comprising using a controllably breakable barrier interposed between the enclosure and the fluid control subassembly. 8. The method according to claim 1, wherein using the fluid control subassembly comprises using the fluid control subassembly, so that the the enclosure enclosing the porous nuclear fuel body is configured to circulate a heat removal fluid through the pores of the nuclear fuel body, so that at least a portion of the heat generated by the nuclear fuel body is removed from the nuclear fuel body and retains the fissile material in the enclosure while the fluid control subassembly circulates the heat removal fluid through the pores of the nuclear fuel body. 9. The method according to claim 1, wherein using the fluid control subassembly comprises using the fluid control subassembly to simultaneously circulate a fission product removal fluid and a heat removal fluid. 10. The method according to claim 1, wherein using the fluid control subassembly comprises using the fluid control subassembly to sequentially circulate a fission product removal fluid and a heat removal fluid. 11. The method according to claim 1, wherein using the fluid control subassembly comprises using a plurality of first components coupled to the fluid control subassembly to supply a fission product removal fluid to the fluid control subassembly, so as to enable the fluid control subassembly to circulate the fission product removal fluid through the pores of the nuclear fuel body, whereby at least a portion of the volatile fission product is acquired by the pores of the nuclear fuel body and is removed from the pores of the nuclear fuel body while said fluid control subassembly circulates the fission product removal fluid through the pores of the nuclear fuel body. 12. The method according to claim 1, wherein using the fluid control subassembly comprises using a dual-purpose circuit coupled to the enclosure to selectively remove the volatile fission product and heat from the nuclear fuel body. 13. The method according to claim 1, wherein using the fluid control subassembly comprises using the fluid control subassembly to circulate a gas through the pores of the nuclear fuel body.