Patent Number: 041586395
Section: description

Referring now to the drawing, there is shown an autoclave 1 having cylindrical sidewalls 2 and endpieces 3 and 4. (It should be understood) that the apparatus described herein is only exemplary of apparatus suitable for practice of the claimed methods. Numerous autoclave designs exist which, with some modifications can be made suitable for the practice of this invention.) The endpieces are held to flanges attached to the cylindrical sidewall by suitable fasteners. Seals 5 in the nature of O-rings are provided to insure that the vessel is pressure tight. Within the autoclave is an insulating hood 6. Preferably, the hood has a removable top cover. Electrical heating elements 7 are positioned along the inside of the hood. In the center of the vessel is a pedestal 8. The vessel endpiece 4 is provided with suitable lead-throughs (not illustrated) for the power lines to the heating elements and for thermocouples for measuring the temperature for control purposes. A pressurizing system for the vessel comprises a valve 9, a pump 10 and reservoir 11 for introducing high pressure gases into the vessel. What has been described to this point is an autoclave of the type used for hot isostatic pressing. The gas in the reservoir is usually argon to protect the electrical heating elements from oxidation. A pressure sensor 12 in communication with the interior of the autoclave provides an electrical output signal indicative of the pressure in the vessel. Adjacent the high pressure vessel is a safety container 20 which has a removable cover 21. The safety container has a gas tank 22 for holding the supply gas or gas to be stored. It also contains a bidirectional pump 26 and valve 23. A conduit 24 passes between valve 23 and into the pressure vessel. A pressure sensor 25 is in communication with the conduit 24 which sensor provides an electrical output indicative of the pressure in the conduit 24. According to this process. a canister is filled with a capturing solid 37 (shown in the breakaway portion of the canister 30) and is placed upon the pedestal 8 while the autoclave cover 3 and the hood cover are removed. The canister is provided with a sealable cover 31 to which is secured a gas valve 32 which when opened enables the interior of the canister to communicate with a fitting 33. A nipple 34 enables the fitting 33 to be connected to the conduit 24. Where the particular process is the encapsulation of radioactive krypton, the canister 30 is filled with a zeolite. The canister is connected as shown in the drawing with the valve 32 in the open position. The autoclave is then closed and bolted. At this time, the canister 30 and the capturing solids 37 are heated within the hood 6 by the heating elements 7. When the temperatures is appropriate to absorption (say, over 500.degree. C.), valves 9 and 23 are open and pumps 10 and 26 are activated so that the pressure of the vessel and the pressure within the canister are simultaneously raised. These pressures are monitored by the sensors 12 and 25 and any pressure differential is recognized by controller 40 which controls the pumps and valves to minimize the pressure difference across the canister wall. The pressures contemplated are in excess of 15,000 psi. At some time the pump 10 may stop and valve 9 close while the pump 22 continues to introduce krypton into the canister 30 as it is absorbed therein. When the krypton can no longer be introduced in the canister without raising the pressure thereof the capturing solid is considered loaded. At that time, the vessel is allowed to cool and the vessel and canister are evacuated maintaining the pressure differential constant until the atmospheric pressures are achieved inside and out of the canister. Then the autoclave cover is open and the valve 32 closed. Nipple 34 and conduit 24 can then be completely evacuated by pump 26 and valve 23 may be closed. The nipple 34 is then disconnected. The canister is ready for storage. In this way, neither of the atmosphere or the inside of the autoclave is ever exposed to radioactive krypton. The advantages according to this invention result from the canister 30 having its own pressure connection protruding through the main vessel closure and thereby during pressurization only the canister internals are exposed to radioactive material. The fact that the canister 30 may be made from thin, that is, relatively nonpressure resistant materials is a considerable advantage in that it permits quick heat up and cool down. Having thus described my invention with the detail and particularity required by the Patent Laws, what is desired protection by Letters Patent is set forth in the following claims.