Aqueous assembly and control method

Abstract

An aqueous assembly has a negative coefficient of reactivity with a magnitude. The aqueous assembly includes a vessel and an aqueous solution, with a fissile solute, supported in the vessel. A reactivity stabilizer is disposed within the aqueous solution to reduce the magnitude of the negative coefficient of reactivity of the aqueous assembly during operation of the aqueous assembly.

What is claimed is: 
     
         1 . An aqueous assembly having a negative coefficient of reactivity, the aqueous assembly comprising:
 a vessel;   an aqueous solution, including a fissile solute, supported in the vessel; and   a reactivity stabilizer disposed within the aqueous solution to reduce a magnitude of the negative coefficient of reactivity of the aqueous assembly during operation of the aqueous assembly, wherein the reactivity stabilizer is a solute of the aqueous solution.   
     
     
         2 . The aqueous assembly of  claim 1 , wherein the coefficient of reactivity is a solution temperature coefficient of reactivity. 
     
     
         3 . The aqueous assembly of  claim 1 , wherein the coefficient of reactivity is a solution void coefficient of reactivity. 
     
     
         4 . The aqueous assembly of  claim 1 , wherein the fissile solute includes uranium. 
     
     
         5 . The aqueous assembly of  claim 1 , wherein the fissile solute includes at least one of uranyl nitrate, uranyl sulfate, and uranyl fluoride. 
     
     
         6 . The aqueous assembly of  claim 1 , wherein the reactivity stabilizer includes boron-10. 
     
     
         7 . The aqueous assembly of  claim 1 , wherein the reactivity stabilizer includes at least one of boric acid, gadolinium-155, and gadolinium-157. 
     
     
         8 . The aqueous assembly of  claim 1 , wherein the aqueous assembly is subcritical, the aqueous assembly further comprising a neutron source for sustaining a fission reaction within the vessel. 
     
     
         9 . The aqueous assembly of  claim 1 , wherein the aqueous assembly is capable of critical operation. 
     
     
         10 . A method of operating an aqueous assembly having a coefficient of reactivity with a magnitude, the method comprising:
 adding an aqueous solution, including a fissile solute, to a vessel;   adding a reactivity stabilizer to the aqueous solution; and   subsequent to adding the reactivity stabilizer, sustaining a fission reaction within the aqueous solution at an effective neutron multiplication factor (k eff ) of 0.9 or greater, wherein the reactivity stabilizer reduces the magnitude of the coefficient of reactivity while the fission reaction is sustained within the aqueous solution.   
     
     
         11 . The method of  claim 10 , further comprising operating a neutron source to sustain the fission reaction with the aqueous solution. 
     
     
         12 . The method of  claim 10 , wherein adding the reactivity stabilizer includes adding at least one of boric acid, gadolinium-155, and gadolinium-157. 
     
     
         13 . The method of  claim 10 , wherein the reactivity stabilizer is a solute of the aqueous solution. 
     
     
         14 . The method of  claim 10 , wherein reducing the magnitude of the coefficient of reactivity includes reducing a magnitude of a negative temperature coefficient of reactivity. 
     
     
         15 . The method of  claim 10 , wherein reducing the magnitude of the coefficient of reactivity includes reducing a magnitude of a negative void coefficient of reactivity. 
     
     
         16 . The method of  claim 10 , further comprising withdrawing a control rod until the aqueous solution achieves criticality. 
     
     
         17 . A subcritical aqueous assembly having a negative coefficient of reactivity, the subcritical aqueous assembly comprising:
 a vessel;   an aqueous solution, including a fissile solute including uranium, supported in the vessel;   a neutron source for sustaining a fission reaction with the fissile solute at a subcritical level within the vessel; and   a reactivity stabilizer disposed within the aqueous solution to reduce a magnitude of the negative coefficient of reactivity of the subcritical aqueous assembly during operation of the subcritical aqueous assembly.   
     
     
         18 . The subcritical aqueous assembly of  claim 17 , wherein the reactivity stabilizer includes at least one of boron-10, gadolinium-155, and gadolinium-157. 
     
     
         19 . A method of operating a subcritical aqueous assembly having a negative coefficient of reactivity with a magnitude, the method comprising:
 adding an aqueous solution, including a fissile solute including uranium, to a vessel;   adding a reactivity stabilizer to the aqueous solution;   operating a neutron source to sustain a fission reaction with the fissile solute of the aqueous solution at a subcritical level; and   reducing the magnitude of the negative coefficient of reactivity of the subcritical aqueous assembly during operation of the subcritical aqueous assembly.   
     
     
         20 . The method of  claim 19 , wherein the reactivity stabilizer is added to the aqueous solution before operating the neutron source.