Methods of producing and recovering plutonium-238

Abstract

Methods of producing plutonium-238 are disclosed. One method includes dissolving neptunium-237 in a nitric acid solution to produce a neptunium target solution, subjecting the neptunium target solution to neutron radiation to produce plutonium-238, and removing the plutonium-238 from the neptunium target solution. A second method includes exposing a solution of neptunium-237 to neutron radiation to produce plutonium-238, complexing the plutonium-238 with an organophosphorus compound, and separating the plutonium-238/organophosphorus compound complex from the solution of neptunium-237. A third method includes dissolving neptunium-237 to form a neptunium-237 target solution, exposing the neptunium-237 to thermal neutrons to produce plutonium-238, utilizing an organophosphorus compound to complex the plutonium-238 and the organophosphorus compound, extracting the plutonium-238/organophosphorus compound complex from the irradiated neptunium target solution, and recovering the plutonium-238.

1 . A method of producing plutonium-238, comprising:
 dissolving neptunium-237 in a nitric acid solution to produce a neptunium target solution;   subjecting the neptunium target solution to neutron radiation to produce plutonium-238; and   removing the plutonium-238 from the irradiated neptunium target solution.   
     
     
         2 . The method of  claim 1 , wherein dissolving neptunium-237 in a nitric acid solution comprises dissolving from approximately 50 g/l to approximately 300 g/l of neptunium-237 in the nitric acid solution. 
     
     
         3 . The method of  claim 1 , wherein subjecting the neptunium target solution to neutron radiation comprises subjecting the neptunium target solution to thermal neutrons. 
     
     
         4 . The method of  claim 1 , wherein removing the plutonium-238 from the irradiated neptunium target solution comprises continuously flowing the plutonium-238 through at least one separation device. 
     
     
         5 . The method of  claim 4 , wherein continuously flowing the plutonium-238 through at least one separation device comprises flowing the plutonium-238 through a centrifugal contactor or an annular centrifugal contactor. 
     
     
         6 . The method of  claim 4 , wherein continuously flowing the plutonium-238 through at least one separation device comprises flowing the plutonium-238 through at least one extraction chromatography column. 
     
     
         7 . A method of producing plutonium-238, comprising:
 exposing a solution of neptunium-237 to neutron radiation to produce plutonium-238;   complexing the plutonium-238 with an organophosphorus compound; and   separating the plutonium-238/organophosphorus compound complex from the irradiated solution of neptunium-237.   
     
     
         8 . The method of  claim 7 , wherein exposing a solution of neptunium-237 to neutron radiation to produce plutonium-238 comprises continuously exposing the solution of neptunium-237 to neutron radiation. 
     
     
         9 . The method of  claim 7 , wherein exposing a solution of neptunium-237 to neutron radiation to produce plutonium-238 comprises flowing the solution of neptunium-237 through a liquid loop and into a neutron source. 
     
     
         10 . The method of  claim 7 , wherein separating the plutonium-238/organophosphorus compound complex from the irradiated solution of neptunium-237 comprises separating the plutonium-238/organophosphorus compound complex from the irradiated solution of neptunium-237 by liquid-liquid extraction. 
     
     
         11 . The method of  claim 7 , wherein separating the plutonium-238/organophosphorus compound complex from the irradiated solution of neptunium-237 comprises separating the plutonium-238/organophosphorus compound complex from the irradiated solution of neptunium-237 by extraction chromatography. 
     
     
         12 . The method of  claim 7 , further comprising recovering ions of the plutonium-238. 
     
     
         13 . A method of producing plutonium-238, comprising:
 dissolving neptunium-237 to form a neptunium-237 target solution;   exposing the neptunium-237 to thermal neutrons to produce plutonium-238;   utilizing an organophosphorus compound with the exposed neptunium-237 target solution to complex the plutonium-238 and the organophosphorus compound;   extracting the plutonium-238/organophosphorus compound complex from the exposed neptunium-237 target solution; and   recovering the plutonium-238.   
     
     
         14 . The method of  claim 13 , wherein dissolving neptunium-237 to form a neptunium-237 target solution comprises dissolving neptunium-237 having a purity of greater than approximately 95% in a nitric acid solution. 
     
     
         15 . The method of  claim 13 , wherein utilizing an organophosphorus compound with the exposed neptunium-237 target solution to complex the plutonium-238 and the organophosphorus compound comprises forming an organophosphorus extractant solution comprising the organophosphorus compound and a diluent and combining the organophosphorus extractant solution with the exposed neptunium-237 target solution. 
     
     
         16 . The method of  claim 13 , wherein utilizing an organophosphorus compound with the exposed neptunium-237 target solution to complex the plutonium-238 and the organophosphorus compound comprises binding the organophosphorus compound to a solid support and contacting the solid support with the exposed neptunium-237 target solution. 
     
     
         17 . The method of  claim 13 , wherein extracting the plutonium-238/organophosphorus compound complex from the exposed neptunium-237 target solution comprises adding an organophosphorus extractant solution comprising the organophosphorus compound and a diluent to the exposed neptunium-237 target solution and partitioning the plutonium-238/organophosphorus compound complex into the organophosphorus extractant solution. 
     
     
         18 . The method of  claim 13 , wherein extracting the plutonium-238/organophosphorus compound complex from the exposed neptunium-237 target solution comprises binding the organophosphorus compound to a solid support and complexing the plutonium-238 to the organophosphorus compound. 
     
     
         19 . The method of  claim 18 , further comprising eluting the plutonium-238 from the organophosphorus compound bound to the solid support. 
     
     
         20 . The method of  claim 13 , further comprising exposing the extracted neptunium-237 target solution to additional thermal neutrons to produce additional plutonium-238.