Patent Number: 
Section: claims

1. A method comprising:flowing a molten salt out of a molten salt reactor at a first temperature, the molten salt comprising a first salt mixture comprising at least uranium, the first temperature being a temperature above the melting point of the first salt mixture, the molten salt reactor comprising a housing with a salt wall coating an interior surface of the housing, the salt wall comprising a second salt mixture, and the second salt mixture being solid at the first temperature;heating the molten salt reactor to a second temperature above the melting point of the second salt mixture causing the second salt mixture to melt;flowing the second salt mixture out of the molten salt reactor;flowing a third salt mixture into the molten salt reactor; andcooling the molten salt reactor from the second temperature to the third temperature causing the third salt mixture to solidify on the interior surface of the housing. 2. The method according to claim 1, wherein the third salt mixture and the second salt mixture comprise the same salt. 3. The method according to claim 1, wherein the third salt mixture comprises the same salts as the second salt mixture with a correct eutectic ratio. 4. The method according to claim 1, wherein the third salt mixture comprises the same salts as the second salt mixture with fewer impurities. 5. The method according to claim 1, further comprising cleaning the interior surface of the housing prior to flowing the third salt mixture into the molten salt reactor. 6. The method according to claim 1, further comprising flowing a molten salt into the molten salt reactor after cooling the molten salt reactor from the second temperature to the first temperature causing the third salt mixture to solidify on the interior surface of the housing. 7. The method according to claim 1, wherein the second salt mixture comprises an actinide and the third salt mixture does not include substantial amounts of actinides. 8. The method according to claim 1, wherein the second temperature is at least 50° C. greater than the first temperature. 9. The method according to claim 1, wherein cooling the molten salt reactor from the second temperature to the first temperature causing the third salt mixture to solidify on the interior surface of the housing continues until the third salt mixture has solidified to a thickness of about 1 centimeter on the interior surface of the housing. 10. The method according to claim 1, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises one or more salts selected from the group consisting of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, and calcium fluoride. 11. The method according to claim 1, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises at least one salt selected from the group consisting of sodium chloride, magnesium chloride, and potassium chloride. 12. The method according to claim 1, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises a salt mixture comprising at least one salt selected from the group consisting of sodium fluoride, magnesium fluoride, and potassium fluoride. 13. A method comprising:flowing a molten salt out of a molten salt reactor at a first temperature, the molten salt comprises a mixture including uranium and one or more salts selected from the group consisting of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, and calcium fluoride;heating the molten salt reactor to a second temperature above the melting point of a second salt mixture disposed as a salt wall on a surface of the molten salt reactor causing the second salt mixture to melt;flowing the second salt mixture out of the molten salt reactor;flowing a third salt mixture into the molten salt reactor; andcooling the molten salt reactor from the second temperature to the third temperature causing the third salt mixture to solidify on the interior surface of the housing. 14. The method according to claim 13, wherein the salt wall comprises a second salt mixture that is solid at the first temperature. 15. The method according to claim 13, wherein the first temperature is a temperature above the melting point of the first salt mixture. 16. The method according to claim 13, wherein the third salt mixture does not include uranium. 17. The method according to claim 13, further comprising flowing a molten salt into the molten salt reactor after cooling the molten salt reactor from the second temperature to the first temperature causing the third salt mixture to solidify on the interior surface of the housing. 18. The method according to claim 13, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises one or more salts selected from the group consisting of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, and calcium fluoride. 19. The method according to claim 13, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises at least one salt selected from the group consisting of sodium chloride, magnesium chloride, and potassium chloride. 20. The method according to claim 13, wherein one or more of the first salt mixture, the second salt mixture, or the third salt mixture comprises a salt mixture comprising at least one salt selected from the group consisting of sodium fluoride, magnesium fluoride, and potassium fluoride.