Patent Number: 049873130
Section: description

SPECIFIC DESCRIPTION As can be seen from FIGS. 1 and 2, a cast-iron treatment, storage and disposal vessel 1 is centered on an axis A and has a wall thickness of 8 centimeters, 12 centimeters or 18 centimeters and has a unitary closed bottom or floor 2. The upper edge or rim of the vessel 1 is stepped and is interfitted with a lid 3 also formed of cast iron and stepped to be complementary to the rim. The cylindrical outer surface of the vessel is not provided with cooling ribs but is smooth so that it can fit within an electric coil heater 20. The latter can be provided with a thermally conductive shell 21 snugly fitting around the wall 1a of the vessel 1 and in heat exchange relationship therewith, a resistance heating coil 22 received in the shell 21 and an outer lining 23 of thermally insulating material. The interior 24 of the vessel may be lined with lead as shown at 25 and a lead lining may likewise be provided at 26 on the underside of the lid 3. The lid 3 is formed with a pair of throughgoing passages 4 and 5 which can be close together as shown in FIG. 1 but also may be spaced apart as shown, for example, in FIG. 4, the passages 4 and 5 being parallel to and offset from the axis A. The passage 4 serves for the introduction of liquids into the vessel and the passage 5 for the withdrawal of vapors and gases therefrom. Although the lid 3 can be formed with it own screwthread to allow it to be turned or screwed down directly into the rim of the vessel 1, here it is secured in place by machine screws 9 angularly equispaced about and threaded into the vessel 1. In a typical application, the condenser concentrate of a nuclear power plant can be held in this vessel while it is heated with the gases or vapors being withdrawn from the vessel. Low temperature and relatively clean steam is withdrawn at subatmospheric pressure while radioactive particulates are left inside. In order to prevent droplets or particles from being aspirated, a downwardly flaring and generally conical relatively flat horizontal plate 6 interrupts direct vertical and axial flow into the passage 5. Thus any rising gases will have to change direction and move horizontally to pass around the plate 6 and then change direction again to enter the passage 5. Gases arising immediately beneath the plate 6 are forced into two more direction changes. In any case it is apparent that this arrangement effectively strips liquid and solid particles from the gas stream aspirated at the passage. The upwardly tapering surface of the plate 6 allows droplets to run smoothly down and drip from its rim back into the liquid or dryng material within the vessel. The upper surface of the lid 3 is formed at the upper ends of the passages 4 and 5 with a shallow cylindrical recess 8 into which is fitted a cylindrical cover 7 that is in turn fixed in place by screws 13 like the screws 9. However, this cylindrical cover can be provided on its rim with a thread which can be threaded directly into an internal thread of the recess 8. Thus the cover 7 has its upper surface flush with that of the lid 3 and seals off both of the passages 4 and 5 making the container safe and easier to handle. It is also possible as seen in FIG. 3 to provide the lid 3 with a passage 10 which can supply material to the vessel and which may be formed with a tube or lance 11 (see U.S. Pat. No. 4,626,380, whose application Ser. No. 06/505,228 was copending with the above-identified parent application). This allows the container to be filled from the bottom up. A lead lining 12 is formed on this container. The vessel 1 is of sufficiently thin construction that its contents can be readily heated by the jackets. In FIG. 4 we have shown an array of such vessels at 30, 31, 32, 33, 34 and 35, respectively provided with heating jackets 36, 37, 38, 39, 40 and 41 in the process of being filled. While one or more of the vessels may be in various stages of the supply of the liquid waste to the vessel, others may be in heating and evacuating stages. Since the filling of each vessel is done in stages, the various vessels shown may be at various stages in filling. The apparatus, however, will be described only with respect to the filling of one of these vessels. Each of the vessels 30-35 has a valve 42-47 connected to its inlet passage 4 which, in the embodiment shown of the container in FIG. 4, can reach below the baffles 48-53 which have been diagrammatically shown therein. Simultaneously, the outlets 5 located above the baffles 48-53 are provided with valves 54-59 which have ultra filters 60-65 downstream thereof. All of the valves described above and to be described below can be electrically actuated from a manually operated or automatically operated control panel, not shown. The filling plant illustrated in FIG. 4 comprises a metering vessel 66 which is in a radiation shield 67 and which receives a quantity of condensate and sludge from the tank of a nuclear power plant via the line 68 and a valve 69. A pipe 70 provided with a valve 71 and reaching to the bottom of the vessel 66 serves to supply the liquid to be reduced in volume by evaporation to the storage vessels 30-35. Vapor which may form above the liquid in the vessel 66 can be drawn off by a valve 72 and a vacuum pump 73 through a liquid separator or trap 74. Since the vacuum pump 73 operates with oil entrained in the fluid traversing same, an oil separator 75 is provided at the downstream side. The vapor may in part condense as a result of this compression and a line 76 which delivers this condensate to a recovered condensate tank 77. A reflux is provided by the condenser 78 which is cooled by a coolant flow from an intermediate heat exchanger 79, the latter being cooled, in turn, by a refrigeration plant 80. Each of the vessels 30-35 thus can receive the incoming liquid from line 70. Each of the vessels also has an outflow line 81-86 passing through a valve 87-92 to a condenser 93-98 cooled by the circulation from the intermediate heat exchanger 79 which may be provided with a pump 99 for this purpose. Any residual vapors can pass via the valves 100-105 through the liquid separators 106-111 to the intake sides of the respective vacuum pumps 112-117. The outflow sides of these vacuum pumps are, in turn, provided with oil separators 1118-123. The collected oil is delivered via line 124 to the oil tank 125 from which the oil can be reinjected into the vacuum pump. The liquid recovered by the traps 74 and 106-111 can pass via line 126 to a filtrate tank 127. The condensate from the condensers 93-98 passes via valves 128-133 to the condensate tank 134. The liquids in tanks 77, 125, 127 and 134 are radioactive and may be recycled for disposal or disposed of in some other way. The outflow from line 135 passes to an absolute filter system preventing the escape of radioactive vapors. In practice, for each of the vessels 30-35, the respective inlet valve 47 (for example for the vessel 35) is opened after its outflow valve 59 has been closed and the vessel 35 has been evacuated so that, by suction, a quantity of liquid is drawn from the vessel 66 via line 70 into the vessel 35. Valve 47 is then closed, valve 59 is opened and the vessel 35 evacuated via the suction pump 117 while the vessel is heated to reduce the volume in the vessel. The vapors which are thus produced are largely condensed in condenser 98 and flow via valve 133 to the condensate tank 134. Residual vapors are subjected to oil and liquid trapping as described. When suction has once again built up in the vessel 35 to the desired level, valve 59 is closed and valve 47 is opened to repeat the cycle. The process is repeated for each of the vessels 30-35 until each vessel is filled and the contents dried to the desired degree. The cover plate 7 is then applied as each vessel is disconnected from the apparatus and the container may be disposed of in a nuclear safe environment. During the evacuation of each vessel 30-35, the baffle 48-53 largely prevents entrainment of droplets therefrom as has been described in connection with FIGS. 1 and 2. If the condensate in tank 134, usually relatively pure water, is not significantly radioactive, it can be discharged directly via a pump 140 and a valve 141 into an industrial waste water treatment system.