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GB2034233A - Storage installation for Liquid Radioactive Material - Google Patents

Storage installation for Liquid Radioactive Material Download PDF

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Publication number
GB2034233A
GB2034233A GB7932549A GB7932549A GB2034233A GB 2034233 A GB2034233 A GB 2034233A GB 7932549 A GB7932549 A GB 7932549A GB 7932549 A GB7932549 A GB 7932549A GB 2034233 A GB2034233 A GB 2034233A
Authority
GB
United Kingdom
Prior art keywords
cooling medium
liquid
tank
radioactive material
storage installation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB7932549A
Other versions
GB2034233B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Atomic Energy Authority
Original Assignee
UK Atomic Energy Authority
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by UK Atomic Energy Authority filed Critical UK Atomic Energy Authority
Priority to GB7932549A priority Critical patent/GB2034233B/en
Publication of GB2034233A publication Critical patent/GB2034233A/en
Application granted granted Critical
Publication of GB2034233B publication Critical patent/GB2034233B/en
Expired legal-status Critical Current

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Classifications

    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21FPROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04Treating liquids
    • G21F9/20Disposal of liquid waste
    • G21F9/22Disposal of liquid waste by storage in a tank or other container

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Structure Of Emergency Protection For Nuclear Reactors (AREA)

Abstract

Radioactive liquids such as solutions and slurries arising from the reprocessing of spent nuclear fuel are stored in coils 2 (only one shown) placed in a shielded tank 1 containing circulating cooling medium. The liquid in the coil is circulated by a fluidic pump 7 driven by a pulsing chamber 4. In the event of a failure in the pumps circulating the cooling medium the decay heat will cause the cooling medium to boil. A reflux condensor fitted to the tank prevents loss of cooling medium during such periods of pump malfunction. <IMAGE>

Description

SPECIFICATION Storage of Radioactive Liquids This invention relates to the storage of liquid radio-active material.
The term "liquid radioactive material" as used in this specification includes within its scope solutions and slurries.
Such solutions and slurries may arise during the reprocessing of irradiated nuclear fuel. When a nuclear fuel has been irradiated in a nuclear reactor it is normally reprocessed to separate uranium and plutonium from the fission products.
The fission products are highly radioactive and have to be stored for very long periods. One method for the long term storage of fission products is to store them as solutions or slurries in large tanks fitted with cooling coils to remove the decay heat and with means for circulating the fission product solution or slurry within the tank.
However it is difficult to ensure that sufficient circulation occurs within the large volume of liquid in the tank to prevent the accumulation of sediment on the tank walls and on the cooling coils which tends to reduce the efficiency of the cooling. As a safety measure there must be spare tanks available to which to transfer the fission product solution or slurry should any defect become apparent in the original tank. The capital investment in such storage tanks is large and it is therefore desirable to reduce the number of spare tanks which have to be provided.
According to the present invention a storage installation for liquid radioactive material comprises pipe circuits containing the liquid radioactive material, means for circulating the liquid radioactive material around the pipe circuits and means for circulating a liquid cooling medium over the external surface of the pipe circuits.
The liquid cooling medium may be in the tank and the pipe circuits may be immersed in the cooling medium and the tank. Alternatively the liquid cooling medium may be passed through the annular gap between co-axial pipes the inner one of which contains the liquid radioactive material.
The liquid cooling medium may be circulated from the tank or the annular gap between the co axial pipes of the alternative pipe circuits described above to a heat exchanger by means of pumps. Should the pumps cease to operate the temperature of the liquid radioactive material within the pipe circuits will rise because of the cessation of flow of the cooling medium. It is undesirable that the liquid radioactive material should boil within the pipe circuits. Additionally, as the temperature of the liquid radioactive material rises the rate of corrosion of the pipe circuits by the liquid material therein also rises. To prevent boiling of the liquid radioactive material and to minimise the corrosion which could occur during a malfunction of the cooling medium circulating pump secondary cooling systems are preferably provided.
In the case of pipe circuits which are immersed in the cooling medium in a tank a condenser may be provided on the tank to prevent loss of any cooling medium should the temperature of the cooling medium be raised to a point at which evaporation of the cooling medium is occurring to a significant extent. The condenser is preferably an air condenser requiring no power input for its operation and it should be of such a size that no loss of cooling medium occurs even if the cooling medium boils.
The said means for circulating the liquid radioactive material around the pipe circuits may comprise fluidic pump means, and such means may be operated by a pulsed-liquid column controlled by air pressure.
The cooling medium may be water but if a tank is used which is fitted with a reflux condenser as described in the preceding paragraph a cooling medium having a boiling point in the range 60 80 C is preferred so that the temperature of the pipe circuits does not rise to a point where the corrosion rate is excessive. Examples of cooling media which may be used include methanol, isopropanol, methylene chloride, carbon tetrachloride and other halogenated hydrocarbons such as those sold under the trade name Freon. In a situation where the pumps circulating the cooling medium are not operating the latent heat of evaporation extracted from the pipe circuits as the cooling medium boils prevents excessive heating in the pipe circuits.
The invention is illustrated by the following description of storage installations for liquid radioactive waste, given by way of example only.
The description has reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of a storage installation for liquid radioactive waste and Figure 2 is a diagrammatic representation of a further storage installation for liquid radioactive waste showing a cooling system for the circulating liquid cooling medium in normal operation and a secondary cooling system.
Referring to Figure 1, the installation illustrated therein comprises a tank 1 containing a liquid cooling medium which may be water and which is circulated by pumps (not shown) through heat exchangers (not shown) to remove the decay heat of the radioactive material. Five pipe circuits 2 (of which only one is shown) are immersed side-byside in the cooling medium in the tank 1. Each pipe circuit 2 is manufactured from seamless stainless steel tube and is provided with a side arm 3 which has a pulsing chamber 4. The liquid in the pulsing chamber is caused to oscillate by air-flow controllers 5, 6 which alternatively introduce air into the pulsing chamber 4 and withdraw it. The oscillating motion of the liquid in the pulsing chamber is converted by a fluidic pump 7 into a circulatory motion around the pipe circuit 2 in the direction of the arrows.The fluidic pump 7 operates on the pulsed fluid diode principle and has no moving parts within the tank 1. A further side arm 8 extends from the pipe circuit to a point above the liquid level in the tank and this further side arm is used for filling and emptying the pipe circuit 2, for removing samples of the liquid for analysis and for providing access for instruments to be lowered into the liquid, for example to measure the temperature of the liquid.
Conveniently the pipe circuit 2 shown in the figure may be manufactured from 108 diameter seamless stainless steel tube and may contain 450 feet of such tube. A pipe circuit so formed would have a capacity of 7 cubic metres.
The pipe circuits 2 are placed in the tank 1 in close packed array to maximise the number of pipe circuits in the tank. Pipe circuits of different shapes, sizes and pipe diameters may be utilised within a tank to maximise the utilisation of the space within the tank.
In use the fluidic pump 7 circulates the liquid radioactive material round the pipe circuit 2. This circulation minimises the possibility of sediment depositing on the walls of the coil which reduces the heat transfer properties of the walls. If water is used as the cooling medium in the tank, it is chemically treated to ensure minimum corrosion of the pipe,.,circuits and tank. The cooling liquid is preferably monitored to detect any increase in radioactivity level which would indicate that a pipe circuit was leaking. In the event that one pipe circuit in a tank leaks only the radioactive material in that circuit has to be transferred to alternative storage faciiities. Thus the amount of spare storage capacity which has to be provided is less than is required for storage in tanks.If one pipe circuit leaks the remaining pipe circuits can remain in the tank and the faulty circuit can be isolated or replaced. Thus the failure of one pipe circuit does not necessitate abandoning the tank and its associated shielding whereas a failure in the tank used for tank storage of radioactive liquids may mean that the tank and the shielding surrounding it become heavily contaminated and cannot be re-used.
An alternative embodiment may be manufactured from tubing having two co-axial tubes. The liquid radioactive material is stored in the inner tube and the cooling medium is circulated through the annular gap between the tubes. The pipe circuit formed from co-axial tubes may be placed in a tank, for example as shown in Figure 1, and may be further cooled by the circulation of a liquid medium such as water in the tank.
Referring now to Figure 2 a tank 1 and a pipe circuit 2 are shown. The pipe circuit is similar to that shown in Figure 1 and the same reference numerals are used to identify the parts thereof. In normal use the cooling medium is withdrawn from the tank 1 through a pipe 10 and passed through a heat exchanger 11 by a pump 12 and returned to the base of the tank 1. The heat exchanger is cooled by water which is circulated by a pump 13 and which is passed down a cooling tower 14. The tank 1 is fitted with an air cooled condenser 1 5 to condense any vapour evaporating from the cooling medium and return it to the tank.
In the event of a malfunction of any of the components of the cooling system which prevent or reduce the circulation of the cooling medium the decay heat emitted by the liquid radioactive material in the pipe circuit 2 will raise the temperature of the liquid material in the piper circuit and of the cooling medium in the tank. If the rise in temperature proceeds for a sufficient length of time the temperature of the cooling medium will rise to its boiling point. The cooling medium then boils and the vapour condenses in the condenser 15 and is returned to the tank 1. As the liquid medium boils, its latent heat of evaporation is extracted from the pipe circuits and the temperature in the pipe circuits will be maintained at a value similar to the boiling point of the medium.The use of a cooling medium having a boiling point in the range 60-800C ensures that the temperature within the pipe circuits does not rise to the boiling point of the liquid radioactive material or to a point where the corrosion rate of the pipe circuits by the liquid radioactive material becomes excessive. In normal use the circulating cooling medium ensures that the temperature of the liquid radioactive material is kept as low as possible and it is only in the situation where the normal circulatory cooling is not operative that the secondary cooling system utilizing the condenser 1 5 is operative.
The cooling medium surrounding the pipe circuits in the present invention acts as an additional barrier facilitating the containment of any leakage which may occur from the pipe circuits. Storage in the pipe circuits rather than in tanks facilitates criticality control of liquids containing plutonium as the pipe circuits can be designed to be safe by geometry. The construction of storage installations according to the present invention is facilitated as thepipe circuits can be tested before being installed. The circulation of the liquid radioactive material and of the cooling medium and the large surface area of the pipe circuits facilitates heat transfer from the liquid radioactive material to the cooling medium.

Claims (9)

Claims
1. A storage installation or liquid radioactive material, comprising pipe circuits for containing the liquid radioactive material, means for circulating the liquid radioactive material around the pipe circuits, and means for circulating a liquid cooling medium over the external surface of the pipe circuits.
2. A storage installation according to claim 1, wherein the liquid cooling medium is in a tank, with the pipe circuits immersed in the cooling medium in the tank.
3. A storage installation according to claim 1, wherein the liquid cooling medium is passed through the annular gap between co-axial pipes of which the inner one is for containing the liquid -radioactive material.
4. A storage installation according to either of claims 2 or 3, including a heat exchanger, and pumping means for circulating liquid cooling medium from the tank or the annular gap between the co-axial pipes (as the case may be) to the heat exchanger for cooling said medium.
5. A storage installation according to claim 4, wherein a secondary cooling system is provided to alleviate the consequences of a failure of said pumping means for said cooling medium, said secondary cooling system including, in the case of the pipe circuits being immersed in cooling medium in a tank, a condenser for condensing any vapour produced by evaporation of the cooling medium and means for returning condensate to said tank.
6. A storage installation according to claim 5, wherein said condenser is an air condenser of sufficient size to avoid loss of cooling medium even under boiling conditions.
7. A storage installation according to claim 1, wherein the means for circulating the liquid radioactive material around the pipe circuits comprises fluidic pump means.
8. A storage installation according to claim 7, wherein operation of the fluidic pump is means by a pulsed-liquid column controlled by air pressure.
9. A storage installation for liquid radioactive material, substantially as hereinbefore described with reference to the accompanying drawings.
GB7932549A 1978-11-07 1979-09-19 Storage installation for liquid radioactive material Expired GB2034233B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7932549A GB2034233B (en) 1978-11-07 1979-09-19 Storage installation for liquid radioactive material

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7843505 1978-11-07
GB7932549A GB2034233B (en) 1978-11-07 1979-09-19 Storage installation for liquid radioactive material

Publications (2)

Publication Number Publication Date
GB2034233A true GB2034233A (en) 1980-06-04
GB2034233B GB2034233B (en) 1982-09-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB7932549A Expired GB2034233B (en) 1978-11-07 1979-09-19 Storage installation for liquid radioactive material

Country Status (1)

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GB (1) GB2034233B (en)

Also Published As

Publication number Publication date
GB2034233B (en) 1982-09-15

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PCNP Patent ceased through non-payment of renewal fee