Patent Number: 
Section: claims

1. A method of removing a radioactive deposit from a nuclear fuel assembly in a nuclear plant, the method comprising: providing a container ( 2 ) arranged to accommodate the nuclear fuel assembly, and arranging said container ( 2 ) in a xcex3-radiation-dampening medium, wherein said xcex3-radiation-dampening medium comprises water, providing a first pumping means ( 3 ,  4 ,  5 ) for feeding by pumping a fluid through the container in order to release the deposit from the nuclear fuel assembly by abrasion and to transport radioactive deposit out of the container, said first means ( 3 ,  4 ,  5 ) also being provided for the feeding of a gas or steam or both to a fluid comprising a mixture of water and ice that is fed into and through the container in order to create a turbulence in the fluid; and further comprising feeding with said first means, a gas or steam or both to said fluid that is fed into and through the container ( 2 ) such that a turbulence is created in the fluid; providing a second receiving means ( 6 ,  7 ) arranged to receive the radioactive deposit transported out of the container ( 2 ) by the fluid, and wherein said second receiving means comprises a filter ( 6 ) arranged to separate released radioactive material from said fluid; arranging at least said second means ( 6 ,  7 ) in said xcex3-radiation-dampening medium, arranging a nuclear fuel assembly ( 1 ) in said container ( 2 ), feeding by pumping with said first pumping means ( 3 ,  4 ,  5 ) said fluid comprising a mixture of water and ice and said gas or steam or both through said container ( 2 ), thereby releasing, by abrasion, a radioactive deposit from said nuclear fuel assembly ( 1 ) and transporting the radioactive deposit out of the container ( 2 ), receiving the transported radioactive deposit in said second means ( 6 , 7 ), and further comprising filtering with said filter to separate from said fluid the radioactive material that is released. 2. The method, according to  claim 1 , which comprises feeding a gas to said fluid that is fed into and through the container such that a turbulence is created in the fluid. claim 1 3. The method, according to  claim 1 , which comprises feeding air to said fluid that is fed into and through the container such that a turbulence is created in the fluid. claim 1 4. The method according, to  claim 1 , which comprises feeding steam to said fluid that is fed into and through the container such that a turbulence is created in the fluid. claim 1 5. The method of  claim 4  wherein said steam comprises water steam. claim 4 6. The method according to  claim 1 , which further comprises arranging said container ( 2 ) and said receiving means in a basin filled with said xcex3-radiation-dampening medium. claim 1 7. The method according to  claim 1 , further comprising irradiating said fuel assembly with infrasound. claim 1 8. The method according to  claim 1 , further comprising rotating said fuel assembly. claim 1 9. The method according to  claim 1 , further comprising heating at least a portion of said fluid that is fed into said container. claim 1 10. The method according to  claim 1  wherein said deposit comprises loose crud. claim 1 11. The method according to  claim 1  wherein the nuclear fuel assembly is a boiling water nuclear fuel assembly and the flow rate of said fluid is about 10-50 kg/s. claim 1 12. The method according to  claim 11  wherein the ice flow is about 30-70% of the water flow. claim 11 13. The method according to  claim 11  wherein said flow rate is 15-35 kg/s. claim 11 14. The method according to  claim 11  wherein said flow rate is 20-25 kg/s. claim 11 15. The method according to  claim 1  wherein the nuclear fuel assembly is a pressure water nuclear fuel assembly and the flow rate of said fluid 50-200 kg/s. claim 1 16. The method according to  claim 15  wherein the flow rate of said ice is about 30-70% of the flow rate of said fluid. claim 15 17. The method according to  claim 15  wherein said flow rate is 75-150 kg/s. claim 15 18. The method according to  claim 15  wherein said flow rate is 100-125 kg/s. claim 15 19. The method of  claim 1  which comprises recycling fluid after the filtering back to said first pumping means. claim 1