Tank closure cesium removal
The invention relates to systems, apparatus and methods for the removal of cesium and other radionuclides from liquid waste contained in a high level waste tank. The invention includes transporting a stream of the liquid waste from the high level waste tank to one or more ion-exchange column assemblies to remove the cesium therefrom using a sorbent, such as, crystalline silico-titanate. The ion-exchange column assemblies include an ion-exchange column and an integrated shield. The column is concentrically positioned within the shield and an air gap is present between the column and the shield to provide passive cooling.
1. An ion-exchange column assembly for removal of cesium from a stream of liquid waste, comprising:
one or more integral, shielded ion-exchange columns, comprising:
a shield base having a perimeter;
a shield cap having a perimeter and positioned opposite the shield base;
a shield wall extending longitudinally between the shield base and the shield cap, extending along the perimeter of each of the shield cap and the shield base, and forming an exterior surface;
a shield cavity formed by the shield wall;
a pressure vessel concentrically positioned within the shield cavity, comprising:
a sorbent bed comprising an ion-exchange resin; and
a head space positioned above the sorbent bed;
an outlet pipe extending through the shield wall, through the head space, into the sorbent bed and along a vertical length thereof;
an inlet pie extending through the shield wall and into the head space; and
an air gap formed by an annular space between an outer surface of the pressure vessel and an inner surface of the shield wall.
2. The ion-exchange column assembly of claim 1 , wherein the ion-exchange resin is crystalline silico-titanate.
3. The ion-exchange column assembly of claim 1 , wherein at least one lug is coupled to the shield cap for use in lifting each of the one or more integral, shielded ion-exchange columns.
4. The ion-exchange column assembly of claim 1 , wherein the pressure vessel contains a sluice pipe extending the vertical length thereof.
5. A cesium removal system, comprising:
a liquid waste stream that flows through a conduit;
one or more pre-filters to receive the liquid waste stream and discharge a filtered liquid waste stream;
an enclosure;
a skid located in the enclosure; and
one or more integral, shielded ion-exchange columns positioned on the skid and located downstream of the one or more pre-filters, to receive the filtered liquid waste stream, separate cesium therefrom, and to discharge a clean liquid stream, the one or more integral, shielded ion-exchange columns, comprising:
a shield base having a perimeter;
a shield cap having a perimeter and positioned opposite the shield base;
a shield wall extending longitudinally between the shield base and the shield cap, extending along the perimeter of each of the shield cap and the shield base, and forming an exterior surface;
a shield cavity formed by the shield wall;
a pressure vessel concentrically positioned within the shield cavity, comprising:
a sorbent bed comprising an ion-exchange resin; and
a head space positioned above the sorbent bed;
an outlet pipe extending through the shield wall, through the head space, into the sorbent bed and along a vertical length thereof;
an inlet pipe extending through the shield wall and into the head space; and
an air gap formed by a space between an outer surface of the pressure vessel and an inner surface of the shield wall.
6. The system of claim 5 , wherein there are two pre-filters and four integral, shielded ion-exchange columns.
7. A method of removing cesium from a liquid waste stream, comprising:
transporting the liquid waste stream through conduit to one or more pre-filters to produce a filtered liquid waste stream;
introducing the filtered liquid waste stream into one or more integral, shielded ion-exchange columns, which comprise:
a shield base having a perimeter;
a shield cap having a perimeter and positioned opposite the shield base;
a shield wall extending longitudinally between the shield base and the shield cap, extending along the perimeter of each of the shield cap and the shield base, and forming an exterior surface;
a shield cavity formed by the shield wall;
a pressure vessel concentrically positioned within the shield cavity, comprising:
a sorbent bed comprising an ion-exchange resin; and
a head space positioned above the sorbent bed;
an outlet pine extending through the shield wall, through the head space, into the sorbent bed and along a vertical length thereof;
an inlet pipe extending through the shield wall and into the head space; and
an air gap formed by an annular space between an outer surface of the pressure vessel and an inner surface of the shield wall;
passing said filtered liquid waste stream through the one or more integral, shielded ion-exchange columns;
separating cesium from the filtered liquid waste stream to produce a clean liquid stream; and
transferring the one or more integral, shielded ion-exchange columns to a storage facility.