DE1113041B - Nuclear reactor with fuel channels and flowing coolant - Google Patents

Description

GERMAN

PATENT OFFICE

U5343Vmc / 21g

REGISTRATION DATE: MAY 12, 1958

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: AUGUST 24, 1961

The invention relates to a nuclear reactor with a number of fuel channels, which fuel elements contain their fission heat from a coolant flowing through each fuel channel which consists of a suspension of liquid particles in a gas or vapor.

In British Patent 735 851, a heat transfer process is described in which a liquid in suspension in a gas is used as a coolant.

The use of spray cooling for a heat exchange process is from "Nuclear Science Abstracts", 8953, 1956, wherein the use of sprayed water to cool the channels in the ORNL graphite reactor is described, and from the volume "Reactor Handbook Engineering" der Book series "Selected Reference Material on Atomic Energy", 1955, in which the extraction of heat from molten Salt is described by spraying liquid bismuth in fine droplets through the salt is.

Processes for separating vapor and liquid are also known, from Volume 3 the series "Peaceful Uses of Atomic Energy", 1955, as well as from the German patent specification 952 929 and British Patent 648 293.

The purpose of the invention is to provide an improved nuclear reactor in which such a Coolant is preferably used in the form of a liquid, which is saturated on its own Steam is brought to suspension, with such a reactor compared to known heat exchange processes has the advantages of achieving relatively high degrees of heat transfer and easy overheating can be achieved. The problems caused by the water absorption of the reactor structure and by the low phase separation at the required flow velocities, as in the state of the Art illustrative publications mentioned are also provided by the present invention made almost meaningless.

The nuclear reactor mentioned at the outset is in accordance with the invention characterized in that a device is provided at the inlet ends of each fuel channel is attached, which generates the liquid particles and introduces them into the gas or vapor stream.

Further tubes can be accommodated in the reactor, which heat-generating fuel elements have and are provided for the evaporated coolant which passes through the further tubes flowing from the separator to overheat.

Nuclear reactor with fuel channels and flowing coolant

Applicant:

United Kingdom Atomic Energy Authority, London

Representative: Dipl.-Ing. E. Schubert, patent attorney, Siegen, Oranienstr. 14th

Claimed priority: Great Britain of May 13, 1957 (No. 15 130/57)

John Desmond Thornton, London, and Henry Reginald Clive Pratt,

Melbourne (Australia) have been named as inventors

The superheater tubes can be arranged in an annular zone which the evaporator tubes surrounds, or vice versa.

The invention is now based on it, for example reproducing drawings are explained in more detail, namely shows or show

1 to 3 diagrammatic vertical sections through cooling pipe element types according to the invention,

FIG. 4 is a diagram of a reactor which has the tubular element design illustrated in FIG. 1, FIG.

FIG. 5 is a diagram of a reactor which has the tubular element design illustrated in FIG. 2, FIG.

6 shows a detail from FIG. 5 on an enlarged scale,

FIG. 7 is a diagram of a reactor which has the tubular element design illustrated in FIG. 3, FIG.

FIG. 8 shows a diagrammatic vertical section through one of the tubular elements of FIG. 7 in an enlarged Scale while the

9 to 11 are diagrammatic circuit representations of some of the possible steam and water connections reproduce between a reactor according to the invention and a steam turbine.

Reference is first made to FIGS. 1 to 3, in which a vertically arranged pipe 1

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contains a rod element 2 made of gap material. The pipe is, for example, one of a plurality of which are arranged parallel to each other so that the fuel elements 2 are combined to thereby to form a critical mass. The parameters or dimensions of the plant are known by known Core data or reference values are determined, and a neutron moderating element is located between the tubes Material or not, depending on whether a thermal or a fast reactor is required.

In Fig. 1 the tube is arranged so that liquid particles from a stream of its own vapor are entrained, namely by the fact that the liquid at the lower end of the tube with a predetermined Speed is supplied, and that tube and fuel element diameter with respect on the amount of heat output of the rod can be chosen so that boiling within a very occurs at a short distance from the lower end of the pipe. This arrangement has an ascending current of "wet" steam.

At the upper end of the tube 1 there is a vapor-liquid separator 3 of conventional type Design type.

In FIG. 2, the pipe 1, the fuel element 2 and the separator 3 are the components of FIG. 1 similar. However, the tube is set up so that liquid particles are entrained in a gas stream which is introduced independently of the liquid at the lower end of the tube. This facility is that a Venturi constriction 4 with radial liquid supply pipes 5, which are connected to a collecting inlet 6 is provided.

It has been found that the structure shown in Fig. 2 achieves a remarkably high heat transfer ratio. From a 9.525 mm diameter element 2 with a smooth surface, which is enclosed over a length of 73.66 cm by a tube 1 with an inner diameter of 12.7 mm, an amount of heat can be released or obtained which exceeds 10 kW, by injecting water into the dry steam, which is supplied at the lower end of the tube at a pressure of 2.10 kg / cm ² , whereby an average pressure in the tube of 1.575 kg / cm ^{2 is} achieved. Thus, in a system which practically does not work under pressure, high heat transfer ratios can be achieved, and even higher or more favorable ratios can be achieved at the higher pressures which are required for power generation.

Another embodiment is shown in FIG. 3, in which the Venturi constriction 4 according to FIG of Fig. 2 is at the top of the tube 1, so that the gas and liquid at the top of the tube 1 are fed or carried away. The gas-liquid separator can then consist of a simple Separating or separating device 3 α exist. It should be noted that the superstructures 2 and 3, which differ from those of FIG. 1, can then also be used can when a liquid become entrained by a gas other than its own vapor target.

4 is a diagram showing how the structure according to FIG. 1 for the purpose of steam generation in a nuclear reactor of the type in which a liquid moderator is used which lies in a cylindrical vessel, the individual tubes of which each have the aforementioned structure are formed. The reactor consists of a cylindrical pressure vessel 7, which is a cylindrical Container 8 surrounds which has a plurality of tubes 1, each of which extends through the upper Extends through the end of the vessel into a zone 9, which by a cylindrical section

10 is formed, in the middle of which there are window slots

11 are located, which establish a connection with an outer zone 12. Each tube 1 is with a Separator 3 equipped above a water level 13, which is defined by a standpipe 14.

The lower ends of the tubes 1 extend

down into an end chamber 15, which by a jacket 16 against a lower zone 17 of the Pressure vessel 7 is thermally insulated and which with

ao a water supply line 18 is equipped. The end chamber is for better illustration 15 shown eccentric to the container. However, there is no practical result from such an arrangement Advantage. For the container 8 supply and ventilation pipes 19 and 20 are provided. Further Pipes la extend through the container 8, between the outer zone 12 and the lower zone 17 of the pressure vessel. The aforementioned lower zone 17 is equipped with a steam outlet 21.

In operation, the reactor can be assumed to be more conventional by pulling it out Control rods (not shown) diverging or increasing performance operates and that water is supplied to the end chamber 15 at such a rate through a pipe 18 therethrough, that boiling takes place immediately at the lower end of the tubes 1 and that a dispersion of water droplets in the steam flows through the above-mentioned pipes upwards, namely around the ones contained therein Fuel elements 2 around. Most of the droplets evaporate before they reach separator 3, taking the heat with them as latent heat of vaporization, while everything is excess Water is separated by the separator and collects at the lower end of zone 9 before it does Level of the water level 13 reached when it is discharged through the pipeline 14. The saturated one Steam then flows through the window slots 11 into the zone 12 and from there down through the pipes la through, where it overheats and removed at outlet 21 will. The jacket 16 prevents the superheated steam through the in the end chamber 15 located water is cooled.

The structure of FIG. 2 can be housed in a reactor in a manner illustrated in FIGS. 5 and 6. In Fig. 5, a pressure jacket 7 a encloses a container 8 a, over which the jacket is divided into inner and outer zones 9 α and 12 a similar to that in FIG. 4. In this embodiment, however, the superheater tubes 1 a are arranged in the middle of the container 8 a, and the steam generating tubes 1, which in this case are provided with Venturi constrictions 4, are located in an annular outer zone of the container 8 a. For each pipe circle 1, ie for each pipe group which is located on a common radius, an end chamber 15 α is provided, and these end chambers

ISa are stepped down towards the center point to allow access to the inner end chambers. In Fig. 6, the lower portion of a tube 1 is shown on an enlarged scale. As can be seen, the ring collecting inlet 6 is equipped with dip tubes 22, and the fuel elements are provided in the form of a tuft or bundle of rods 2 α which are connected to an apertured hollow cone 23 which rests in a conical seat 24. After each end chamber 15 a, a tangential supply line 18a is provided (Fig. 5), and the cylindrical section 10 α extends downward beyond the container 8 a, thereby creating an outlet for the superheated steam. A gas space 16 α serves the inner end chamber 15a against the from the cylindrical section 10 a flowing superheated steam to isolate.

Standpipes (not shown), which, however, resemble the pipeline 14 in FIG. 4, are provided for the return of the water that collects in the zone 12 a below the separator to the respective end chambers 15 α .

During operation, a steam and water mixture is introduced or fed into each end chamber 15 a. The water separates itself as a result of the tangential supply, and it collects at the lower end of the end chamber, from where it is drawn off by means of the Venturi effect of the dip tubes 22 and carried along by the steam as it flows through each tube. The water that flows out at the upper end of the tubes is excreted or separated and returned to the end chambers. In the meantime, saturated steam flows through the window slits 11 into the inner zone 9 α , down through the superheater tubes 1 a and is ejected centrally at the lower end of the reactor.

A further embodiment of the reactor according to the invention is shown in FIGS. 7 and 8, in which, for example, a structure illustrated in FIG. A central zone of the reactor is used for steam generation, while an outer zone, similar to FIG. 4, is provided for superheating, although this embodiment can easily be adapted to central superheating, as is the case with FIG is. An annular outlet manifold 26 is provided for each pressure pipe set which sits on a common radius, and each manifold 26 is connected to pipelines 27 or is emptied through these to a steam and water drum 28. Each such pressure tube set has a ring inlet manifold 40, to which steam is supplied. The entrained water has a tendency to settle in the collecting line and in a separator 25 a, while the steam continues to flow to the upper end of each pressure tube 25 and enters the Venturi tube 4 α. The steam and water drum performs the function of the separation device 3 a according to FIG. 3 for all pipe elements 1, and from it steam outlet connections 29 go to the superheaters.

The Venturi constriction 4a is created by a ring collecting line 6 is supplied with water, which through the dip tubes 22 from the water supply in the separation device 25 a is fed here. The steam from the reactors can be used to drive power or high-voltage turbines can be used in conventional circulatory systems as illustrated in FIGS. 9-11. Fig. 9 illustrates an open loop system which can be used for a reactor, such as it is described, for example, with reference to FIGS. 1 to 4, in which the water is not separated is injected into the steam, but due to the dimensions of the tubes and fuel element rods, which are selected for special heat output ratios, is carried away.

The water is fed through the pipeline 30 to the steam generating zone 31 of the reactor, where it is evaporated, as already described. At the outlet end of the zone 31, the remaining water droplets are separated from the saturated steam, the water is returned to the supply line 30 and the steam is passed through the superheating zone 32 of the reactor, from where it is passed on to the turbine T and the condenser C , while the condensate to the supply line 30 is returned. Alternatively, the water feed rate can be controlled or kept under control in such a way that the emerging steam is just dry or, alternatively, is overheated.

FIGS. 10 and 11 illustrate closed loop systems which are suitable for reactors as described with reference to FIGS. 5 and 6 or 7 and 8, in which water and steam are injected separately into the reactor. In the cycle system illustrated in FIG. 10, the steam generating zone 31 of the reactor is fed with water through a supply line 30, while it is fed with saturated steam through the steam line 33. At the outlet end of zone 31, the water is again separated from the steam and returned to supply line 30, while the steam flows through superheating zone 32 and then to turbine T and condenser C and the condensate is returned to supply line 30 . A part of the saturated steam leaving the zone 31 is, however, sucked off through the steam pipe 33 and returned into the reactor.

In the loop system of the Loeffler type shown in FIG. 11, all of the saturated steam which leaves the separators at the outlet of the steam generating zone 31 of the reactor flows through the superheating zone 32 of the reactor. Most of the superheated steam is routed after the turbine and condenser. However, part of the superheated steam is sucked off through the pipe 34 after the mixer M , while part of the condensate is sucked off from the condenser C through the pipe 35 after the mixer. In the mixer M , the superheated steam and the condensate are mixed with one another in the proportions which are necessary to bring the steam out of its superheat state, and the saturated steam is then fed via the steam line 33 to the reactor. The mass of the condensate from the condenser C is, as before, returned through the supply line 30 immediately after the reactor.

The temperature of the condensate leaving the condenser C is generally too low to feed it to the reactor. But it can get through

Heat exchangers are heated by steam sucked from the turbine in a known manner will be fed.

Alternatively, the condensate can pass through heat exchangers are heated, which are used to cool the moderator of the reactor.

Claims (5)

PATENT CLAIMS: 1. Nuclear reactor with a number of fuel channels containing soft fuel elements whose fission heat is removed by a coolant flowing through each fuel channel, which consists of a suspension of liquid particles in a gas or vapor, characterized in that at the inlet ends of each fuel channel one Device is attached, which generates the liquid particles and introduces them into the gas or vapor stream. 2. Nuclear reactor according to claim 1, characterized in that that the devices at the inlet end of each fuel channel are reserve tanks for the liquid which forms the liquid particles, in which the lower end of each fuel channel is immersed in such a way that the liquid boils at the lower end and one Dispersion of the liquid in its own vapor rises within the fuel channels. 3. Nuclear reactor according to claim 1, characterized in that the devices at the inlet end of each fuel channel a Venturi constriction and such a constriction have leading liquid supply that the gas, which through the constriction flowing through it into the fuel channel, liquid particles from the liquid supply carried away. 4. Nuclear reactor according to claim 3, characterized in that that the liquid supply has a dip tube which is inserted into a liquid separation device, which is mounted in a gas supply nozzle at the other end of the fuel channel, is immersed. 5. Nuclear reactor according to claim 4, characterized in that that each has an annular end chamber, the gas supply nozzle and the liquid separation device for one tube group each, which is at the same radial distance from the vertical Axis of the reactor lies. Considered publications: German Patent No. 952,919; British Patent No. 648 293; "Nuclear Science Abstracts", 10, No. 19, Abstract, 8953, 1956; Vol. "Reactor Handbook: Engineering" of the book series "Selected Reference Material on Atomic Energy ", 1955, p. 778; Vol. 3 of the series "Proceedings of the International Conference on the Peaceful Uses of Atomic Energy", 1955, pp. 116 to 120. For this purpose 2 sheets of drawings © 109 679/178 8.