Removal of tritium from gas-cooled nuclear reactors

Claim 2

In a method of operating a gas-cooled nuclear reactor having a core in which the heavy hydrogen isotope tritium is present as a radioactive contaminant, the reactor including a primary circuit for circulating a coolant gas through the core, said method including the step of cooling said core by circulating the coolant gas through the primary circuit including the core of said reactor, the improvement comprising removing tritium from said coolant gas in said primary circuit by the steps of introducing hydrogen or a hydrogen-containing compound into said coolant gas in said primary circuit and flowing the hydrogen or a hydrogen containing compound mixed with the coolant gas through said primary circuit including the core whereby tritium in said circuit and core is entrained in the mixture comprising said cooling gas and said hydrogen or hydrogen-containing compound and subsequently removing said tritium from said mixture.

Claim 3

A method as claimed in claim 1, wherein said hydrogen or said hydrogen-containing compound is introduced intermittently into said coolant gas in the primary circuit.

Claim 4

A method as claimed in claim 1, wherein a concentration of from about 1,000 to about 5,000 μ at. of hydrogen or hydrogen-containing gas is maintained for several hours in said coolant gas in said primary circuit.

Claim 5

A method as claimed in claim 1, wherein said hydrogen-containing compound is in the form of a hydrocarbon.

Claim 6

A method as claimed in claim 4, wherein said hydrocarbon is methane.

Claim 7

A method as claimed in claim 1, wherein said hydrogen-containing compound is ammonia.

Claim 8

A method as claimed in claim 1, wherein said hydrogen-containing compound is in gaseous phase.

Claim 9

A method as claimed in claim 1, wherein said hydrogen or said hydrogen-containing compound is introduced into said coolant gas before said coolant gas enters said core during said circulation of said gas.

Claim 10

A method as claimed in claim 1, wherein said tritium is removed from said mixture in a purification plant.

Claim 11

A method as claimed in claim 9, wherein said purification plant is incorporated in a by-pass of said primary circuit.

Claim 12

A method as claimed in claim 1, wherein the removal of tritium from the mixture is effected by withdrawing at least a portion of the mixture comprising cooling gas and said hydrogen or hydrogen-containing compound in which the tritium is entrained from said primary circuit and circulating the mixture through a purification plant for removing the tritium from the mixture and reintroducing the cooling gas into the primary circuit.

Claim 13

A method as claimed in claim 11, wherein the removal of the tritium is effected by oxidizing the tritium by passing the mixture containing the tritium over copper oxide.

Claim 14

A method as claimed in claim 11, wherein the removal of tritium is effected by catalytic combustion on contact with platinum with excess oxygen and removing water produced in the catalytic combustion.

Claim 15

In a method of operating a gas-cooled nuclear reactor having a core in which the heavy hydrogen isotope tritium is present as a radio-active contaminant and a closed primary circuit through which a coolant gas circulates, the core being located in the path of the primary coolant, the method including the step of cooling the core by circulating the cooling gas through the primary circuit including the core, the improvement comprising introducing hydrogen or a hydrogen-containing compound into a cooling gas in the primary circuit and circulating the mixture of the cooling gas and the hydrogen or hydrogen containing mixture through the core for removing tritium from the core, removing a portion of the mixture of the cooling gas and hydrogen or hydrogen containing compound from the primary circuit after the mixture has circulated through the core, removing tritium from the removed portion of the mixture and, after such removal, reintroducing the cooling gas back into the primary circuit.

Claim 16

In a method of operating a gas-cooled nuclear reactor having a core in which the heavy hydrogen isotope tritium is present as a radio-active contaminant and a closed primary circuit through which a coolant gas circulates, the core being located in the path of the primary coolant, the method including the step of cooling the core by circulating the cooling gas through the primary circuit including the core, the improvement comprising introducing hydrogen or a hydrogen-containing compound into a cooling gas in the primary circuit and circulating the mixture of the cooling gas and the hydrogen or hydrogen containing mixture through the core for removing tritium from the core, removing a portion of the mixture of the cooling gas and hydrogen or hydrogen containing compound from the primary circuit after the mixture has circulated through the core, removing tritium from the removed portion of the mixture and, after such removal, reintroducing the cooling gas back into the primary circuit.