Method to extract tritium from irradiated boiling water reactor control rod blades
View Patent ↗A method for extracting tritium from irradiated boiling water reactor control rods that have cruciform-shaped. Bands of a malleable metal are wrapped around the flat portions of the blades, one band near the top of each blade panel and a second band near the bottom. The bands are crimped and an inlet penetration is formed through one of the bands and the panel and an outlet penetration is formed through the second band and the panel. A termination of each end of a closed loop conduit is sealably connected to the inlet and outlet for transporting a carrier gas through the interior of the panel. The carrier gas passing through the interior transports the tritium out of the panel to a tritium getter filter to capture the tritium. The carrier gas then recirculates through the system.
1. A method for extracting tritium from an irradiated boiling water reactor control rod having cruciform shaped blades that have been removed from service, the control rod blades having an elongated dimension along an axial length thereof, a clad exterior and an interior chamber housing a neutron absorbing material, the method comprising the steps of:
segmenting the cruciform shaped control rod blades longitudinally along a central spline to separate the blades into four separate panels;
separately placing a first band of malleable metal laterally around at least some of the panels, respectively, substantially at a first end;
separately placing a second band of malleable metal around the at least some of the panels, respectively, substantially at a second end;
crimping the bands of malleable metal to the clad exterior of the panels;
forming an inlet penetration through the band of malleable metal and clad exterior of the panels at the first end;
forming an outlet penetration through the band of malleable metal and clad exterior of the panels at the second end;
connecting a conduit to the interior of the clad exterior of the panels in a substantially closed loop from the inlet penetration through the clad exterior of the panels substantially at the first end along the elongated dimension of the clad exterior of the panels to the outlet penetration through the clad exterior of the panels substantially at the second end along the elongated dimension of the clad exterior of the panels;
transporting a carrier fluid into the inlet penetration and out the outlet penetration and through the conduit; and
passing the carrier fluid from the outlet penetration through a tritium getter filter before returning the carrier fluid to the inlet penetration.
2. The method of claim 1 wherein the carrier fluid is a gas.
3. The method of claim 2 wherein the gas is either oxygen or argon.
4. The method of claim 1 wherein the carrier fluid is heated prior to entering the inlet penetration.
5. The method of claim 1 wherein the tritium getter filter has an active ingredient comprising yttrium or zirconium.
6. The method of claim 1 wherein the step of transporting the carrier fluid includes the step of pumping the carrier fluid under pressure.
7. The method of claim 1 wherein the step of transporting the carrier fluid includes the step of drawing the carrier fluid through the conduit with a vacuum.
8. The method of claim 1 wherein the bands of malleable metal are formed from 303 stainless steel.
9. The method of claim 1 wherein the bands of malleable metal are approximately ⅛ in. (0.32 cm.) thick and 4 to 6 in. (10.16 to 15.24 cm.) in width.