Radioactive salt solution storage system

Abstract

The improved system for receiving and storing radioactive salt solution includes a tank configured to receive the radioactive salt solution while preventing a criticality accident, a solution inlet for conveying the radioactive salt solution to the tank, an overflow bottle, and a cap sealing the top of the tank. The cap includes a side Y-joint with a side pipe configured to direct the radioactive salt solution from the solution inlet to the tank, a vertical pipe configured to direct gas from the tank to a ventilation system, and an overflow line configured to convey excess radioactive salt solution from the tank to the overflow bottle. A gap between the side pipe and the solution inlet prevents the radioactive salt solution from backflowing into the solution inlet. The control system includes a level switch configured to provide a signal indicating that the tank contains a maximum capacity of the radioactive salt solution, a first valve configured to stop the flow of the radioactive salt solution to the side pipe upon receiving a signal from the level switch, and a second valve configured to allow the flow of the radioactive salt solution from the tank to the overflow line.

Description

[Technical Field]

[0001] Various exemplary embodiments disclosed herein generally relate to a system for storing toxic radioactive salt solutions. [Background technology]

[0002] Acid-deficient uranyl nitrate solutions are used in sol-gel processes for fuel fabrication. However, such solutions are toxic, necessitating the development of systems for safely storing unused or discarded uranyl nitrate solutions, as well as other radioactive salt solutions. Furthermore, the uranium concentration of acid-deficient uranyl nitrate solutions ranges from 0.5 M to 3.5 M, and the pH ranges from 0.5 to 2.8. Therefore, the storage system for uranyl nitrate solutions must be able to withstand exposure to highly acidic conditions.

[0003] Other radioactive salt solutions can be used in the sol-gel process for fuel fabrication, including various nitrates of radioactive metals. Ceramic fuel elements based on uranium, thorium, and plutonium are produced from acidic solutions of UO2(NO3)2 (uranyl nitrate), U(NO3)6 (uranium nitrate), K2UO2(SO4)2 (potassium uranyl sulfate), UO2(SO4) (uranyl sulfate), U(SO4)2 (uranium sulfate), uranium phosphate, Th(NO3)4, or Pu(NO3)4. Therefore, the system for safely storing unused or discarded radioactive salt solutions is suitable for storing a variety of radioactive metal salts.

[0004] In view of the above, it would be desirable to develop an improved method and system for storing toxic radioactive salt solutions. Summary of the Invention

[0005] In light of the current need for storage of hazardous, radioactive, or other dangerous liquid materials, a summary of various embodiments is provided below. While simplifications and omissions may be present in the following summary, these are intended to highlight and introduce certain aspects of the embodiments disclosed herein and are not intended to limit the scope of the invention. Detailed descriptions of the embodiments necessary to understand and utilize the inventive concepts are provided in later sections.

[0006] Various embodiments disclosed herein relate to a system for receiving and storing a radioactive salt solution, including a tank having a width and an upper portion and configured to receive the radioactive salt solution while preventing a criticality accident; a solution inlet for conveying the radioactive salt solution to the tank; an overflow bottle; a cap for sealing the upper end of the tank; and a first gap between a side pipe and the solution inlet, the first gap being configured to prevent backflow of the radioactive salt solution into the solution inlet.

[0007] In various embodiments, the cap has a lateral Y-joint including a lateral pipe configured to direct the radioactive salt solution from the solution inlet into the tank, a vertical pipe configured to direct gas from the tank to a ventilation system, and an overflow line configured to carry excess radioactive salt solution from the tank to the overflow bottle.

[0008] The system for receiving and storing the radioactive salt solution can include an intake for a ventilation system configured to receive gas from the tank, and a second gap between the intake and a vertical pipe configured to prevent flow of the radioactive salt solution into the intake.

[0009] In various embodiments, the system includes a control system including a level switch configured to provide a signal indicating that the tank is full, i.e., contains a maximum capacity of radioactive salt solution; a first valve configured to stop the flow of radioactive salt solution from the solution inlet to the side pipe upon receiving a signal from the level switch; and a second valve configured to permit the flow of radioactive salt solution from the tank to the overflow line and permit the flow of gas from the tank to the air inlet. The first valve is configured to be normally closed to prevent overfilling of the tank in the event of a malfunction, and the second valve is configured to be normally open to prevent spillage of the radioactive salt solution when the tank is being filled in the event of a malfunction. The second valve is configured to close when the tank is not being filled or drained, thereby preventing the escape of liquid or gas within the tank. In various embodiments, the first and second valves are solenoid valves.

[0010] The system for receiving and storing the radioactive salt solution may also include a solution outlet at the bottom of the tank and a valve configured to allow the radioactive salt solution in the tank to flow through the solution outlet, thereby emptying the tank.

[0011] The system for receiving and storing the radioactive salt solution can include an input pump configured to pump the radioactive salt solution into the solution inlet, the input pump stopping pumping the radioactive salt solution upon receiving a signal from the level switch, thereby preventing overfilling of the tank.

[0012] In various embodiments, an overflow bottle in a system for receiving and storing radioactive salt solution includes a container having a mouth, a cap including a vent configured to capture harmful vapors, and an opening welded to the overflow line, and means for releasably securing the cap to the mouth of the container, the means for releasably securing the cap to the mouth of the container being a tri-clamp fitting, a clamp having hinged C-shaped clamping portions configured to engage the outer periphery of the cap and the outer periphery of the mouth, or external threads on the mouth of the container configured to mate with corresponding internal threads on the cap. [Brief explanation of the drawings]

[0013] For a better understanding of various exemplary embodiments, reference is made to the accompanying drawings. [Figure 1] FIG. 1 illustrates a system for receiving and storing a radioactive salt solution. [Figure 2] FIG. 2 illustrates a control system for managing fluid flow in the system of FIG. 1. [Figure 3] 1 illustrates a system for receiving and storing a radioactive salt solution, including a tank configured to receive the radioactive salt solution, and a cap with a lateral Y-joint. [Figure 4] FIG. [Figure 5] FIG. 5 shows the tank mounted on a rack using the tank support plate of FIG. 4. [Figure 6] 2 shows an overflow bottle for use in the system of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0014] Waste or discarded acid-deficient uranyl nitrate (ADUN) solution must be stored safely. Safe ADUN storage requires geometrically safe tanks, i.e., tanks with an outside diameter of approximately 5 inches or less, 4.5 inches or less, or 4 inches or less, to prevent the possibility of a criticality accident. The tanks must be chemically resistant to concentrated nitric acid.

[0015] While storage of ADUN solutions is of particular interest herein, other radioactive salt solutions used as precursors for the formation of radioactive ceramic nuclear fuels by sol-gel processes can also be stored in the systems disclosed herein. Suitable radioactive salt solutions include acidic solutions of UO2(NO3)2 (uranyl nitrate), Th(NO3)4, Pu(NO3)4, and mixtures thereof. Uranium, thorium, and plutonium-based radioactive salt solutions can be acidic solutions of UO2(NO3)2 (uranyl nitrate), U(NO3)6 (uranium nitrate), K2UO2(SO4)2 (potassium uranyl sulfate), UO2(SO4) (uranyl sulfate), U(SO4)2 (uranium sulfate), uranium phosphate, Th(NO3)4, or Pu(NO3)4.

[0016] The acid-deficient uranyl nitrate solution can be prepared by dissolving uranium oxide in aqueous nitric acid to produce a uranium solution, placing the uranium solution under pressure of 5 to 40 atmospheres in a sealed reaction chamber, and heating the uranium solution to a desired holding temperature between 150°C and 250°C. After holding the uranium solution in the sealed vessel at the desired holding temperature for the desired holding time, the pressure and temperature of the uranium solution are reduced to produce the acid-deficient uranyl nitrate solution.

[0017] Once the acid-deficient uranyl nitrate solution is prepared, it is converted into ceramic nuclear fuel particles by sol-gel processes known in the art. Such conversion can occur immediately, or the acid-deficient uranyl nitrate solution can be stored in an acid-resistant tank for later use.

[0018] Storage of waste acid-deficient uranyl nitrate (ADUN) requires geometrically safe tanks to prevent the possibility of a criticality accident. Generally, the tank can have any desired height but must have a narrow width to avoid excessive accumulation of nuclear material at any point along the tank's height. Chemical resistance to concentrated nitric acid is required because acid-deficient uranyl nitrate forms in nitric acid solutions. The tank must be designed to eliminate the possibility of backflow of solution into the solution inlet, which can be achieved by including an air gap. The tank must be sealable to simultaneously limit gas venting and overflow of ADUN solution from the tank.

[0019] The tank must include a ventilation intake to remove gas from the tank during filling and draining operations, and ventilation from the tank must not be shut off unless all gas entering or leaving the tank is stopped. Additional features of the system include an overflow line that can carry excess liquid from the tank, a level switch to stop the flow of ADUN solution before the tank is full, and any droplet removal device installed within the tank to limit the discharge of droplets of solution into the ventilation intake.

[0020] The systems disclosed herein for receiving and storing radioactive salt solutions include the following improved design features: a backflow prevention inlet flange (BSIF) that prevents backflow of the solution, provides an independent overflow path, interfaces with the facility's ventilation system, and allows the tank to be sealed to prevent vapor release; a criticality safety tank support (CTS) that allows the tank to be attached to integrated process equipment; and a criticality safety tank overflow bottle (CTOB) that provides a final containment path for the solution in the event of an overflow.

[0021] FIG. 1 illustrates a system for receiving and storing radioactive salt solutions, such as ADUN. It includes tank 1 having an outer diameter y and a height x. In various embodiments, tank 1 can be formed from vertically oriented stainless steel pipe with an outer diameter y of 5 to 12.5 cm, 2 to 5 inches, 10 to 11.5 cm, or 4 to 4.5 inches. Tanks of this diameter are sometimes used in the nuclear fuel processing industry to prevent potential criticality accidents due to excessive accumulation of radioactive material at any depth within the tank. In various embodiments, the tank can have a height x of 0.5 to 5 meters, 1 to 4.5 meters, 2 to 4 meters, or 3 to 3.8 meters. The tank can have an outer diameter y of 11 to 11.5 cm and a height x of 3.5 to 3.6 m, and can be sealed at the top and bottom to form a tank with a capacity of approximately 30 L. Tank 1 is geometrically safe to prevent the possibility of criticality accidents during radioactive salt storage, and the stainless steel material is chemically resistant to concentrated nitric acid.

[0022] The system disclosed herein is suitable for receiving and storing solutions containing any fissile material within a fuel fabrication facility. Soluble salts of uranium, thorium, or plutonium, or their oxidized forms, can be used. The only constraint is material compatibility between Tank 1 and the solution. Solutions of uranium, thorium, or plutonium salts in aqueous sulfuric, nitric, or phosphoric acid solutions are compatible with Tank 1 made of stainless steel. Solutions of uranium, thorium, or plutonium salts in hydrochloric acid are incompatible with stainless steel because they corrode stainless steel. If it is necessary to store solutions of uranium, thorium, or plutonium salts in hydrochloric acid, Tank 1 can be constructed of glass pipe.

[0023] The upper end of the tank 1 is sealed with a backflow prevention inlet flange and includes a cap 2 having the flange. The cap 2 includes a side Y-joint 5 with a vertical pipe and a side pipe 4. The side pipe 4 is configured to direct the radioactive salt solution from the solution inlet into the interior of the tank 1. The vertical pipe of the side Y-joint 5 is configured to exhaust the gas inside the tank 1 to a ventilation system. The tank 1 may include a droplet removal device 17 to enhance the removal of droplets of the radioactive salt solution from the gas exhausted from the tank 1. The droplet removal device 17 may be a mesh-type coalescer that combines droplets into larger droplets. The droplet removal device 17 may be a knitted wire mesh pad droplet removal device, a woven mesh droplet removal device, a nonwoven mesh droplet removal device, or a droplet removal device formed from a finely perforated plate or series of plates. The droplet removal device 17 is located within the tank 1 directly below the cap 2.

[0024] To prevent spillage of the radioactive salt solution if tank 1 overflows during filling, an overflow line 13 carries excess radioactive salt solution from side wye fitting 5 to criticality safety tank overflow bottle 12. This is shown in detail in Figure 6. The pipe in side wye fitting 5 may have an outer diameter larger than the diameter of the opening of overflow bottle 12. The outer diameter of overflow line 13 may be the same as the inner diameter of side wye fitting 5 as it exits fitting 5. To compensate for the difference between the initial outer diameter of overflow line 13 and the diameter of the overflow bottle opening, one or more pipe diameter reduction fittings 8 and 9 may be used to reduce the diameter of overflow line 13.

[0025] A valve 3 may be arranged between the cap 2 and the side Y-joint 5. When the valve 3 is open, during filling of the tank 1, the radioactive salt solution flows into the inside of the tank 1 through the side pipe 4, and the gas in the tank 1 is discharged to the ventilation system through the vertical pipe of the joint 5. When the valve 3 is closed, the radioactive salt solution is stored in the tank 1, preventing the solution from spilling and the gas from discharging. The valve 3 may be controlled by a control device 3a.

[0026] Tank 1 includes a solution outlet 14 at the bottom of the tank, which allows the contents of tank 1 to be drained and collected. Valve 7 can be used to open and close solution outlet 14. Branch flow path 15, which is opened and closed by valve 6, may be used to sample the radioactive salt solution in tank 1.

[0027] The overflow line 13 may be fitted with a viewing window 16. The interior of the overflow line 13 is monitored by a camera or optical sensor 10 to detect radioactive salt solution in the overflow line 13. If radioactive salt solution is detected in the overflow line 13, the sensor 10 sends a signal to the CPU 11.

[0028] In various embodiments, tank 1 is fabricated from nominal pipe size (NPS) 4 to 5 stainless steel pipe, and cap 2 on top of tank 1 is a flange cap for NPS4 or NPS5 pipe as required. The flange cap has two ports machined into it: one ¾ inch port for a level switch and one 2 inch port for connection to a side wye fitting via valve 3. In various embodiments, the inlet assembly includes valve 3 (which may be a 2 inch solenoid valve) and side wye fitting 5 (a 2 inch side wye fitting modified with a 2 inch overflow line and side pipe 4 with a funnel-shaped opening).

[0029] Figure 2 shows a control system for managing the flow of feed solution and exhaust air in the system of Figure 1. Cap 2 on tank 1 includes level switch 31, which is configured to provide a signal indicating that tank 1 has reached its maximum capacity of radioactive salt solution, i.e., tank 1 is full. First valve 21 is configured to stop the flow of radioactive salt solution from solution inlet 20 to side pipe 4 upon receiving a signal from the level switch. Second valve 3, also shown in Figure 1, is configured to allow the flow of radioactive salt solution from tank 1 to overflow line 13 (not shown in Figure 2) and the flow of gas from tank 1 to the ventilation system through ventilation inlet 23.

[0030] When level switch 31 detects that tank 1 is full, it sends a signal to CPU 22, which may or may not be the same as CPU 11 in FIG. 1. Upon receiving the signal from level switch 31, CPU 22 sends a first signal to the input pump, which delivers radioactive salt solution to solution inlet 20, causing the input pump to stop, preventing tank 1 from overfilling. CPU 22 also sends a second signal to valve 21, causing it to close and stop the flow of radioactive salt solution from solution inlet 20 to side pipe 4, preventing tank 1 from overfilling. CPU 22 then sends a third signal to valve 3, opening it to allow the flow of radioactive salt solution from tank 1 to overflow line 13 and the flow of gas from tank 1 to ventilation intake 23.

[0031] Valve 21 is normally set to a closed position so that in the unlikely event of a failure of valve 21, it will fail in the closed position to prevent overfilling of the tank. Valve 21 is designed to block flow from the solution inlet. During tank filling, CPU 22 signals valve 21 to open, allowing radioactive salt solution to flow into Tank 1.

[0032] Valve 3 is set to a normally open position so that in the unlikely event of a failure of valve 3, it will fail in the open position to prevent spillage of radioactive salt solution while the tank is being filled. When the tank is not being filled or drained, valve 3 is closed, sealing the radioactive salt solution and vapors within tank 1 and limiting radioactive or hazardous emissions. During normal operation, valve 3 and valve 21 work in tandem to allow flow only under conditions that prevent backflow.

[0033] In various embodiments, valves 3 and 21 are remotely actuated valves. Suitable remotely actuated valves include pneumatically actuated air valves, electrically operated valves, and solenoid valves.

[0034] 3A-3C show an embodiment of the disclosed system for receiving and storing radioactive salt solution. The system includes a tank 1 having an outer diameter y of, for example, 4.5 inches and a height x of, for example, 141 inches. FIGS. 3A and 3B show the bottom of tank 1, which includes a radioactive salt solution outlet with flange 37 and valve 38.

[0035] 3A and 3C show the top of tank 1, including cap 2. Cap 2 includes a level switch 31 that is attached to a first opening of cap 2 for use with the control system of FIG. 2. Side wye fitting 5 is connected to a second opening of cap 2 via valve 36. When the tank is being filled, radioactive salt solution flows from solution inlet 34 through valve 35 to side pipe 4 of side wye fitting 5. During the filling operation, both valves 35 and 36 are open, allowing the radioactive salt solution to flow from inlet 34, through the side wye fitting, and via valve 36 into tank 1. After the tank is filled, both valves 35 and 36 are closed to prevent spillage of the radioactive salt solution.

[0036] An overflow pipe 32 extends from the vertical pipe of the side Y-fitting 5. If the tank 1 is overfilled during the filling operation, excess solution may backflow into the side Y-fitting 5. This solution is drained through the overflow pipe 32 into an overflow bottle (shown in Figure 1). This prevents excess solution from spilling out of the opening in the side pipe 4 that receives solution from the inlet 34 or the ventilation opening in the vertical pipe of the side Y-fitting 5.

[0037] As shown in Figure 3C, ventilation inlet 33 is shaped like an inverted funnel. Gases within tank 1, which may be radioactive or contain nitric acid vapors, may escape tank 1 through valve 36 during the filling operation and pass through the vertical pipe of side Y-fitting 5. When suction is applied to ventilation inlet 33, the gases escaping tank 1 are drawn into ventilation inlet 33.

[0038] The side Y-fitting 5 provides a solution input through the side pipe 4, an independent ventilation path through the vertical pipe, and an independent overflow path through the overflow pipe 32. The placement of the side Y-fitting 5 above the valve 36 allows the tank 1 to be sealed without blocking the ventilation path. The ventilation path through the vertical pipe of the side Y-fitting 5 must remain passively open during operation. If the ventilation path and the solution inlet were separate inlets to the cap 2, the ventilation path valve could fail in the open position, resulting in a lack of passive safety. Because the ventilation inlet 33 and the solution inlet 34 are both above the valve 36, when the valve 36 is closed, the tank is not operating and gas cannot escape from the tank. Therefore, filling from the ventilation inlet and the solution inlet is coordinated by this component.

[0039] The systems shown in Figures 3A-3C include a means for preventing back-pressure backflow into the solution inlet 34. Such backflow is caused by downstream pressure greater than the inlet pressure. As shown in Figure 3C, backflow can be prevented by providing an air gap between the solution inlet 34 and the side pipe 4. If desired, the air gap can be replaced with a mechanical backflow prevention device to introduce a physical barrier to backflow. Mechanical backflow prevention devices include a reduced pressure principle assembly, a double check valve assembly, or a pressure vacuum breaker assembly.

[0040] A second air gap may be provided between the ventilation inlet 33 and the opening of the vertical pipe of the side wye 5. This air gap prevents radioactive salt solution in the side wye 5 from being sucked into the ventilation inlet 33.

[0041] 3B and 3C, during the filling operation, valves 35 and 36 are both open, allowing incoming solution to enter Tank 1 through valves 35 and 36 while allowing gas to vent through valve 36. During the filling operation, valve 38 is closed to retain the solution within Tank 1. After filling is complete, both valves 35 and 36 are closed, and valve 38 is also closed, to prevent the tank from overfilling or the gas or radioactive salt solution from escaping Tank 1. When emptying Tank 1, valve 38 is opened to allow the radioactive salt solution to flow out of Tank 1, and valve 36 is opened to allow atmospheric air to enter Tank 1 to prevent a vacuum from forming within the tank.

[0042] FIG. 4 illustrates a criticality-safe tank support structure, including a tank support plate 44, for use in the system of FIG. 3A. The tank support plate 44 has a length and width m and a central hole 41 with a diameter y′, where y′ = y + Δ, and the diameter y′ is larger than the outer diameter of the tank 1 by Δ, allowing the lower end of the tank 1 to slide through the opening of the central hole 41 without interference. The holes 42 are arranged to receive bolts that pass through the flange 37 of FIG. 3B, and these holes 42 are arranged concentrically with the central hole 41. In various embodiments, each hole 42 has a corresponding hole 42 on the opposite side of the central hole 41, and each pair of holes 42 is separated by a distance p. The tank support plate 44 also includes holes 43 along its edge. The holes 43 are configured to receive bolts that pass through the support pedestals (shown in FIG. 5). Each pair of adjacent holes 43 is separated by a distance n. Each hole 43 is separated from the edge of the tank support plate 44 by a distance q.

[0043] Figure 5 shows the tank of Figure 3B attached to the tank support plate 44 of Figure 4, with the tank support plate 44 shown in cross section. The outer diameter of the tank 1 is y' and the inner diameter is y. The tank 1 passes through a central hole 41 in the tank support plate 44. The flange 37 of the tank 1 is bolted to the tank support plate 44 with a bolt 52 having a head 51. The bolt 52 passes through the hole 42 in the tank support plate 44 and is secured in place with a nut 53. The tank support plate 44 is bolted to a support base 56 with a bolt 54. The bolt 54 passes through the hole 43 in the tank support plate 44 (shown in Figure 4) and is secured in place with a nut 53. This tank support plate 44 to flange 37 bolting system provides rigid support for the tank. As shown in Figure 5, the tank 1 includes an outlet 57 leading to a valve 38.

[0044] In various embodiments, an NPS4 or NPS5 pipe flange is used as flange 37, which is bolted to tank support plate 44. Flange 37 is also secured to the exterior of tank 1 in much the same way that cap 2 is secured to the top of tank 1. Tank support plate 44 is secured to support pedestal 56, which provides rigid support for tank 1.

[0045] FIG. 6 illustrates an overflow bottle 12 for connection to the overflow line 13 of FIG. 1. The bottle 12 has a capacity of 0.5 to 5 liters, 0.7 to 4 liters, 0.75 to 2.25 liters, or 0.8 to 1.2 liters. The bottle 12 has a closure 64 with a first opening configured to receive a vent 61 for venting gases inside. The closure 64 has a second opening 62 adapted for connection to the overflow line 13. In various embodiments, the bottle 12 and the closure 64 are made of an acid-resistant material, such as stainless steel. The opening 62 may be butt-welded to the overflow line 13. A means 63 for securing the bottle 12 to the closure 64 is provided. In various embodiments, the closure 64 has an outer periphery with internal threads, and the bottle 12 has an opening with external threads that correspond to the internal threads, allowing the bottle 12 to be unscrewed and removed from the closure 64. In various embodiments, the closure 64 and bottle 12 are secured together with a tri-clamp closure, or a clamp having hinged C-shaped clamp portions that are configured to engage the outer periphery of the cap and the outer periphery of the mouth.

[0046] Although various embodiments have been described in detail with particular reference to certain aspects, it should be understood that the invention is capable of other embodiments and its details are susceptible to modification in various obvious respects. Those skilled in the art will recognize that variations and modifications are possible within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and drawings are for illustrative purposes only and do not in any way limit the invention, which is defined solely by the claims.

Claims

1. 1. A system for receiving and storing a radioactive salt solution, comprising: a tank having a width, the tank having an upper portion and a lower portion, the tank being configured to receive the radioactive salt solution while preventing a criticality accident; a solution inlet for delivering the radioactive salt solution to the tank; Overflow bottle and a cap that seals the top end of the tank; a first gap between a side pipe and the solution inlet, the first gap being configured to prevent backflow of the radioactive salt solution into the solution inlet; the cap has a lateral Y-joint including the lateral pipe configured to direct the radioactive salt solution from the solution inlet to the tank, a vertical pipe configured to direct gas from the tank to a ventilation system, and an overflow line configured to carry excess radioactive salt solution from the tank to the overflow bottle.

2. 10. The system of claim 1, an inlet for a ventilation system configured to receive gas from the tank, and a second gap between the inlet and a vertical pipe configured to prevent flow of the radioactive salt solution into the inlet; The system further comprises:

3. 3. The system of claim 2, a level switch configured to provide a signal indicating that the tank contains a maximum volume of the radioactive salt solution; a first valve configured to stop the flow of radioactive salt solution from the solution inlet to the side pipe upon receiving a signal from the level switch; a second valve configured to permit the flow of radioactive salt solution from the tank to the overflow line and to permit the flow of gas from the tank to the air inlet; The system further comprises:

4. 4. The system of claim 3, the first valve being configured in a normally closed state to prevent overfilling of the tank in the event of a malfunction; the second valve is set to a normally open state to prevent spillage of radioactive salt solution when the tank is filling in the event of a malfunction; and The system wherein the second valve is configured to close when the tank is not being filled or drained.

5. 4. The system of claim 3, wherein the first valve and the second valve are solenoid valves.

6. 10. The system of claim 1, a solution outlet at the bottom of the tank; and a valve configured to allow the radioactive salt solution in the tank to flow through the solution outlet when in an open state; The system further comprises:

7. 4. The system of claim 3, an input pump configured to pump the radioactive salt solution into the solution inlet; The input pump stops pumping the radioactive salt solution upon receiving a signal from the level switch. The system further comprises:

8. 10. The system of claim 1, The overflow bottle a container having a mouth; Cap and the cap has a vent configured to capture harmful vapors and an opening welded to the overflow line; means for removably securing the cap to the mouth of the container; A system including:

9. 9. The system of claim 8, means for removably securing the cap to the opening of the container, a clamp having a hinged C-shaped clamp portion, the clamp configured to engage an outer periphery of the cap and an outer periphery of the mouth; system.

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