Fuel cell and gas-cooled nuclear reactor using such fuel cells

FIELD: fuel cells designed for use in gas-cooled nuclear reactor core.

SUBSTANCE: fuel cell 10 designed for use in gas-cooled nuclear reactor has assembly of two adjacent fuel plates 12a, 12b disposed relative to one another and shaped so that they form channels 14 for gaseous coolant flow. Fuel plates 12a, 12b incorporate elementary fissionable particles, better non-coated ones, implanted in metal matrix. Metal coating may be deposited on both ends of each plate 12a and 12b.

EFFECT: enlarged heat-transfer surface, enhanced power density per volume unit.

13 cl, 5 dwg, 1 tbl

The technical field

The present invention relates, in General, to the fuel element designed for use in the core of a nuclear reactor cooled by the gas cooler.

The present invention also relates to nuclear gas-cooled reactor active zone, made up of fuel elements of this type.

In particular, a nuclear reactor in accordance with the present invention can be used with depleted uranium.

Prior art

In most nuclear reactors are used at the work of the nuclear fuel in the form of pellets, set the stack in a sealed metal casing. This shell with the nuclear fuel pellets has the form of a fuel rod. Fuel rods are grouped in bundles on a rigid frame so that the formed fuel assemblies of a nuclear reactor. A similar design is usually laid to develop nuclear reactors.

The drawback of such conventional means of forming nuclear fuel is that they limit the amount of heat that may be dissipated per unit volume of the active zone of a nuclear reactor using a gas cooler. The heat dissipated by the pill nuclear fuel is transferred to the coolant circulating between terminals che is ez gas, contained in the space that separates the tablet from the shell, and then through the material of the shell. In addition, the contact area of heat transfer surface between conventional fuel rods and coolant is relatively low.

Moreover, a portion of the length of each conventional fuel cell is reserved for devices intended for fixation of tablets and for the expansion of the gas generated during nuclear division. Therefore, each fuel cell generates heat only part of its length. As a result, the heat exchange surface between the rods and the coolant is used only in the useful volume of the reactor core, in other words, the volume of the active zone of the reactor in which heat is efficiently generated by the nuclear fuel. Thus determined by the heat transfer area for useful cubic meter of the active zone of the nuclear reactor.

For example, if we consider the case of the active zone of the nuclear reactor, formed out of the ordinary assemblies of fuel elements consisting of rods with a diameter of 8 mm, arranged in a triangular lattice, in which the distance between the centers of the rods is equal to 12 mm, the heat exchange surface for useful cubic meter of the active zone is less than 202 square meters.

This limitation surface area taproom is on a per unit volume of the active zone of the nuclear reactor is applied to limit the maximum temperature of the material fuel, which limits the power density per unit volume, in other words, the energy output per unit volume of the active zone of the nuclear reactor.

This limitation is particularly serious for nuclear reactors cooled gas cooler. For these reactors require large area of heat transfer surface for power dissipation of the active zone of the nuclear reactor during normal operation, or to dissipate the residual power after an emergency stop.

This situation requires to limit the power density per unit volume to a relatively low value. It is not possible to fully utilize the neutron active zone of the nuclear reactor, particularly of the fast reactor. This situation also makes it unprofitable operating costs for this type of reactors, because of the limits of power density means that the size of a nuclear reactor and the building containing the reactor becomes very large if the reactor should be built economically acceptable total energy output.

Although until recently used the usual Assembly of elements of the nuclear fuel in the last few years there have been studies and experiments on fuel cells, formed of fissile particles with a coating, and Ameriabank in the carbon matrix. Such fuel cells are intended primarily for use in high temperature nuclear reactors, cooled by gas, such as helium.

Fissile particles coated contain spherical fissile core, covered with several successively deposited layers, in particular, includes an inner porous layer, which may contain gases, formed by division, and can withstand the expansion of the cores, and a layer of silicon carbide SiC, forming a sealed barrier to fission products. Such particles are referred to as particle type "TRISO". Their diameter varies from several hundred microns to several millimeters, depending on the production process.

Currently, there are two types of fuel cells, in which particles coated agglomerated in various forms in the carbon matrix.

In the first type of fuel cells, developed in the USA and in France, the particles coated agglomerated in the form of cylindrical rods, which are then injected into a vertical tubular channels formed for this purpose in a graphite block with a hexagonal cross-section that forms the active zone of high-temperature nuclear reactor with gas cooling. Cylindrical rods made by agglomerating particles coated in a matrix on the basis of gr is hitovogo powder.

In fuel cells of the second type, developed in Germany, the particles coated agglomerated in the form of beads, pressed graphite balls of the same size for the formation of the active zone of high-temperature nuclear reactor with gas cooling. Balls made by agglomerating particles coated in a carbon matrix, so that formed the Central part of the ball, with subsequent covering the Central part of the outer layer that does not contain any particles with a coating.

Fuel cells are formed from particles coated, agglomerated in the form of rods or balls, have the important advantage that they are easier and cheaper to manufacture than conventional nuclear fuel Assembly, formed from bundles of rods.

However, they also have serious disadvantages.

Such fuel cells can only be used in a nuclear reactor with a thermal spectrum, because the fissile particles coated linked together by graphite, in other words, the environment, slowing down the neutrons.

Another disadvantage of the fuel cell of this type is that it is not very suitable for industrial application, in particular, due to the fact that the industrial processing elements for periodic updates of the fractions of the reactor core is full-time is difficult. And finally, it is impossible to independently control the heat transfer and heat loss or geometry of the fuel element in the reactor vessel, particularly at high values of the velocity of the cooling gas.

The invention

The present invention is mainly directed to the fuel cell with the new design, which can be used in a nuclear reactor, cooled gas cooler while providing substantially greater surface area of heat transfer and power density per unit volume than conventional fuel assemblies.

In accordance with the present invention this can be achieved by using a fuel cell to the active zone of a nuclear reactor using a gas cooler, and the specified fuel cell differs in that it contains lots located adjacent to each other plates containing elementary fissile particles embedded in a metal matrix, and the shape of the adjacent fuel plates is selected in such a way that they jointly form the multiple channels through which can flow the gas cooler.

In a fuel cell of this type fuel plates are assembled so that they form channels through which flows the gas cooler. The resulting layout of analogichnoe conventional heat exchanger. Therefore, can be used all the technologies used for the production of heat exchangers. Thus, the fuel elements may be made of plates arranged essentially parallel to each other, between which is placed a corrugated plate. Alternatively, all of the fuel plates in a single element can be made corrugated. The geometry of the fuel element can be flat, round, spiral, etc.

In one of the preferred variants of the embodiment of the present invention, the channels through which flows a gaseous refrigerant formed essentially parallel to each other.

In addition, the fuel plates are preferably over the entire height of the active zone of the nuclear reactor, and the channels are essentially vertically.

In accordance with the first option layout cross-section of the channels are essentially the same throughout their length.

In accordance with another possible layout of the cross-section of the channels sequentially varies along the direction of flow of the gaseous refrigerant, and each channel includes a tapered entrance portion and expanding the output part. With this arrangement the pressure of the gaseous refrigerant can be reduced by narrowing the input side of the channel, and trace the educational, cooling of the active zone of the nuclear reactor can be more effective due to the fact that the temperature of the gaseous refrigerant will be less than when the same cross-section channels. This arrangement also allows you to compress gaseous refrigerant in the outlet diffuser at subsonic conditions.

In a preferred variant embodiment of the present invention is a division of elementary fissile particles, which are introduced together with reproducing the substance directly into the metal matrix. Each plate can then be formed directly by rolling or may be laminated simultaneously with the metal coating on each of its sides.

Alternatively, elementary fissile particles contain a coating of fissile and fertile substances and embedded in a metal matrix. In this case, the fuel plate is obtained directly by rolling.

The elements that form the basic fissile particles are uranium and/or plutonium, and/or thorium. It should be noted that depleted uranium, consisting mainly of uranium-238 can be used with the fuel element, in accordance with the present invention.

Another object of the present invention is a nuclear reactor cooled gas cooler is, active area which is formed from fuel cells of the above type. A reactor of this type is distinguished, in particular, the fact that the neutron flux in the core, essentially, is a fast neutron flux.

The gas cooler is preferably a carbon dioxide CO₂, helium, air or argon.

Control of the reactor of this type can be provided with control devices on the basis of boron carbide In₄With made with the possibility of introducing them between the fuel elements.

Brief description of drawings

Next will be described the preferred embodiment of the present invention as a non-limiting example with reference to the accompanying drawings, on which:

figure 1 depicts a fuel cell made in accordance with the first variant embodiment of the present invention, a perspective view;

figure 2 - fuel element according to figure 1 in cross section in a horizontal plane in an enlarged scale;

figure 3 - fuel cell according to the alternative embodiment in cross section similar to figure 2;

figure 4 - fuel cell according to another variant embodiment in accordance with the present invention, a perspective view;

figure 5 - neutron spectrum obtained for the infinite among the s by computing provided that the fuel elements in accordance with the present invention are used to form the active zone of the nuclear reactor, cooled by carbon dioxide CO₂.

A detailed description of the preferred variants of the embodiment of the present invention

The elements described in different embodiments of the invention that perform similar functions are denoted by the same positions.

Figure 1 schematically shows in perspective the fuel cell 10 corresponding to the first variant embodiment of the present invention.

In accordance with one of the essential features of the present invention, the fuel cell 10 includes an Assembly of many located adjacent to each other of the fuel plates. In a variant embodiment, shown in figures 1 and 2, the adjacent fuel elements contain flat plate 12A, installed parallel to each other, and corrugated plate 12b. Flat plate 12A and corrugated plates 12b are installed alternately, in other words, each of the corrugated plates 12b is placed between two flat plates 12A. However, it is obvious that such an arrangement is shown only as one example of the present invention, which is by no means limiting, as various fuel plates that form the fuel cell 10, could the t to be installed using a variety of other forms, without departing from the scope of the present invention, as will be described below.

The expression "fuel plate" means that each of the plates, such as 12A and 12b, the fuel element 10 is solid and in itself contains nuclear fuel, in other words, dividing the environment.

The fuel plates, such as 12A and 12b in the shape of thin plates, in other words, the plates have a thickness of several millimeters. As a non-limiting example, the thickness of the plates 12A and 12b may be approximately 2 mm

Each of the plates, such as 12A and 12b, manufactured by rolling or joint rolling cermet material consisting of elementary fissile particles embedded in a metal matrix. In the case of non-planar plates, such as corrugated plates 12b, the plate is formed into, for example, by using a press.

Elementary fissile particles are essentially spherical in shape with diameter of the order of several hundreds of microns. Each of them contains fissile element consisting of plutonium and/or uranium.

The metal matrix is made out of a material such as molybdenum, steel, tungsten, zirconium or zirconium alloy Zircaloy (registered trademark).

Since the fuel cell 10 is designed for use in a nuclear reactor cooled by the gas cooler, which divides the I substance, contained in the elementary fissile particles, preferably has no coverage, in other words, fissile substance embedded in a metal matrix, without applying one or more coatings. Gases division, highlights of these particles and are then contacted with a metal matrix. In particular, such a plate can be obtained by rolling a metal workpiece with a higher concentration of fissile particle at its center than near its edges.

If this technology for the production of plates 12A and 12b cannot guarantee that between elementary fissile particles will always be a certain amount of metal, and two side plates must be sealed from the gases formed by the fission particles, each of the lateral sides of the plate may be formed of a metal coating. The fuel plates, such as 12A and 12b, then made by rolling together with the application of the above coatings. In this case, the metal coating selected from the same group of materials as the material of the matrix.

Alternatively, it is also possible to use elementary fissile particles consisting of fissile material, with a coating, in other words, covered with several protective layers, in particular the coating of silicon carbide SiC. In this case, it is not necessary to use a metal coating on each side of the fuel plate, and the plate can be made directly by rolling and possibly forming.

In accordance with one of the essential characteristics of the present invention different fuel plate, such as 12A and 12b used in the structure of the fuel cell 10, is collected in such a way that adjacent fuel plates together form several channels 14 through which freely flows through the gas cooler. The channels 14 are preferably formed essentially parallel to each other.

In the variant embodiment shown in figures 1 and 2, the fuel element 10 consists of an Assembly of flat plates 12A and corrugated plates 12b, all of the cross-section of the channels 14 essentially has the tapered shape of an isosceles triangle.

This arrangement is comparable to the layout used in a plate heat exchanger, and allows to obtain a relatively large surface area of heat exchange between the material fuel and a gaseous coolant. For illustration, when the plates 12A and 12b have a thickness of 2 mm, pitch corrugation plates 12b is 12 mm, and the distance between the mean planes of the two adjacent flat plates 12A is 10 mm, perimeter heating for each channel 14 is Aven 43,8 mm, and the area of heat transfer surface per unit volume for the entire active zone of the nuclear reactor is equal to 436/m

In addition, the structure in the form of a single block of plates, such as 12A and 12b, is a means of achieving efficient heat transfer between the material of the fuel contained in the wafer, and a gas cooler. Thus, we reach the required target.

More generally, the shape of different plates, such as 12A and 12b used in the composition of the fuel element 10, in accordance with this invention is chosen so as to provide the largest possible surface area of heat exchange between the walls of these plates and the gas cooler, while maintaining reasonable values of the flow resistance. This leads to large values of the surface area of heat exchange between the material fuel and a gas cooler per unit volume of the active zone of the nuclear reactor.

This design feature in combination with very good thermal conductivity of the cermet fuel plates has many advantages. Some of these advantages are the ability to obtain a power density per unit volume, which satisfies the neutron structure of the active zone of the nuclear reactor and allows you to choose the appropriate dimensions of the reactor and accordingly reduces required in which the fixed assets housing implementation. In addition, the above arrangement enables to provide very good thermal behavior at work due to the small temperature difference between the material fuel and a gas cooler. In particular, it allows you to provide work with natural circulation, if conventional cooling means, such as the fan used to circulate the cooling gas in the reactor, freezes when shutting down the system for the selection of the residual power. Finally, the above arrangement enables to reduce the amount of heat accumulated in the fuel, in other words, to reduce the fuel temperature, which simplifies the management of accidental transients.

Different fuel plate, such as 12A and 12b used in the composition of the fuel element 10 may be assembled using any appropriate means. Thus, as schematically shown in figure 1, the fuel plates may be held in contact with each other through the casing 16 with a rectangular cross-section, surrounding all of the fuel plate on both sides of the stack of plates, and on each side of the stack, which is mounted parallel to the channels 14. Alternatively, the casing 16 may be replaced by two or more fixing devices surrounding the stack of plates, or a set of bolts or equivalent devices to which Alenia, passing through the stack of plates, or by gluing or welding of the adjacent plates, etc.

As shown in figure 1, the fuel cell 10 is designed to be installed vertically in the core of a nuclear reactor with a gas cooling. The channels 14 of the flow of the gas cooler when it is oriented essentially vertically, and the refrigerant circulates in them from the bottom up. In addition, the fuel cell 10 and the components of its fuel plates 12A and 12b are preferably over the entire height of the active zone of the nuclear reactor.

In a variant embodiment, shown as an example in figures 1 and 2, all corrugated plate 12b are made identical, and their curves are along the same line, so that each of the flat plates 12A in turn is in contact with the curves of the first corrugated plate 12b mounted on one side of this flat plate 12A, and with the curves of the corrugated plate 12b mounted on the other side of the plate 12A.

Figure 3 shows another example of the first variant embodiment, in which the corrugated plate 12b is installed with a uniform offset to one bending corrugated plate 12b with respect to the next plate. Therefore, the two surfaces of each of the flat plates 12A are simultaneously in contact with one bend each and the corrugated plates 12b, set on each side of this flat plate. In other words, sequentially installed corrugated plate 12b are symmetrical relative to the Central plane of a flat plate 12A, which is located between them.

As indicated above, various fuel plates that form the fuel cell 10 can be installed using a variety of other forms without departing from the scope of the present invention. This flat plate 12A in the variant presented in figure 3, can be excluded. In addition, in variants of the embodiment shown in figures 1-3, the height of the bending plates 12b may be different and/or can be used in more complex forms. In addition, in all cases, instead of using a flat plate, the stack of plates can be minimized so that there is formed a spiral or a circle or other cross-section. In General, all technologies that are commonly used in heat exchangers, consisting of stacks of plates can be moved to production fuel cell 10, in accordance with the present invention.

In the above description, the channels 14 for the flow of gaseous refrigerant is formed between the fuel plates are of approximately uniform cross-section along their whole length. As schematically shown in figure 4, the channels 14 can also have a lane is Menno cross-section. Each of the channels 14 may contain consistently converging inlet section located at the bottom and a diverging outlet section in the upper part so that the diffuser is formed along the direction of flow of gaseous coolant inside the fuel element 10, in other words, from the bottom up.

This arrangement allows gaseous refrigerant expanded in a convergent inlet portion of each of the channels.

This provides more efficient cooling of the active zone of the nuclear reactor, as the temperature of the gaseous refrigerant will be lower than it would be if the cross-section of the channels 14 was uniform. In addition, the gas refrigerant is compressed in a divergent output part at subsonic conditions.

As an illustration of the fuel cell 10 described above with reference to figure 1, made in the form of panels, for example, with dimensions of 2 m in length or height, 47 cm wide and 7.2 cm in thickness. A panel of this type is obtained by assembling fifteen fuel plates with a thickness of 2 mm, each of which contains eight flat plates 12A and seven corrugated plates 12b, the distance between the mean planes of the two adjacent flat plates 12A is 10 mm and the distance between two successive bends of the corrugated plates 12b is also 10 mm

As already mentioned, t is Kai layout allows you to obtain the area of heat transfer surface per unit volume, equal 436/m, the hydraulic diameter of 5.2 mm, and perimeter heating 43,8 mm

Fuel cells 10 in accordance with the present invention is designed for use in the core of a nuclear reactor with a gas cooling. The gas cooler can be a carbon dioxide CO₂, helium, compressed air or argon.

Simple calculations show that a nuclear reactor cooled by using one of these gases, the active area which is formed from the fuel cell 10, in accordance with the present invention may have either a relatively limited power density and very long service life of the active zone of the nuclear reactor, or a higher power density and a satisfactory service life.

Thus, if carbon dioxide CO₂circulates in the core of a nuclear reactor with a cross-section of 9 m²and a height of 2 m, consisting of a fuel cell 10 of this type is that shown in figures 1 and 2, we get a very long service life with the speed at the exit from the active zone of the nuclear reactor, equal to 40 m/s, and the temperature of the inlet and outlet respectively 250°and 600°C. In this case, the exchange of thermal energy is 1753 mW, which produces electricity with a capacity of 720 mW and ratio polisrahvaste about 41%. The power density in the fuel is limited to 195 mW/m³and relatively low flow per unit area (225 kW/m²)that due to the very large surface area exchange gives the temperature difference is less than 65°between the center of the fuel element and the cooling gas. Fuel temperature at the hottest point will be less than 700°C. the pressure Loss due to flow of carbon dioxide through the core of a nuclear reactor of approximately 3 bar.

Significantly higher power density is obtained by using a carbon dioxide pressure of 40 bar, with a flow rate at the exit from the active zone of the nuclear reactor 50 m/s and the input and output temperatures of carbon dioxide 250°and 800°s, respectively. In this case, thermal capacity of the active zone of the nuclear reactor reaches 2816 mW, which corresponds to the electric power 1240 mW when the efficiency of 43%. The power density in the fuel equal 319,11 mW/m³fuel temperature in the core of a nuclear reactor will be slightly less than 900°and the expected pressure loss during the passage through the core will be somewhat less than 4 bars.

Characteristics of electric power (1200 mW), similar characteristics in the second case above, can be received with use the of helium as a coolant at a pressure of 70 bar, outlet velocity from the active zone of the nuclear reactor of 65 m/s and temperatures at the inlet and exit from the active zone of the nuclear reactor 260°900°C. In this case, the maximum fuel temperature is less than 1000°and the pressure loss in the core of a nuclear reactor will be less than 1 bar.

As mentioned above, the elementary fissile particles contained in the fuel plates, such as 12A and 12b formed of fissile elements such as uranium and/or plutonium, and possibly reproducing elements, such as thorium.

More precisely, the uranium particles preferably are in the form of dioxide depleted uranium UO₂and plutonium dioxide. The expression dioxide depleted uranium" means particles containing 0.25% uranium 235 and of 99.75% of uranium 238.

Particles of plutonium are usually obtained in the form of plutonium dioxide PuO₂using plutonium extracted from existing nuclear reactors operating in the water under pressure. Therefore, it is preferable to use plutonium "class of 2016", in other words, the plutonium with an average composition corresponding to the composition, which is obtained in 2016, electric nuclear reactors with a capacity of 900 mW, running water under pressure, after three normal cycles with cooling for three years, subsequent processing and manufacturing within the next the two years.

In the composition according to the first example, each of the fuel plates may contain 34% of the particles UO₂, 16% of the particles PuO₂and 50% of the metal matrix, by volume. As indicated above, the material of the matrix may consist, in particular, molybdenum, steel, tungsten, zirconium or alloy Zircaloy (registered trademark). Obviously, such a composition is given merely as illustrations, and content of fissile nuclei will be optimized as a function of management strategies for use in the core of a nuclear reactor.

Calculations were performed on the basis of this composition using a computer program APOLLO 2 for CEA (Commissariat a l Energie Atomique - nuclear energy Commission). In these calculations it was assumed that the particles PuO₂were obtained from PU class of 2016.

The figure 5 shows the neutron spectrum obtained in calculations for a nuclear reactor, in which an active area is formed from the fuel cell with a composition corresponding to the above example. In other words, in the figure 5 presents the distribution of neutron flux (PS^-1Cm^-2) as a function of energy (in electron-volts) in an infinite medium.

Such neutron spectrum shows that the neutron flux in the core of a nuclear reactor, essentially, performance is made by a fast neutron flux (the rate of about 40000 km/s). In particular, the flow can be considered as zero below the threshold energy of approximately 50 electron volts, and as nearly equal to zero in the resonant range of uranium 238. This feature allows to reduce the speed of resonance neutron capture in uranium-238 by reducing the formation of uranium 239. This feature also represents a means of increasing the rate of fission in a fast spectrum uranium 238 with a significant improvement in the ratio of delayed neutrons β_eff.

In addition, calculations for neutrons show that fuel cells in accordance with the present invention, used with the above arrangement, Assembly, can provide a very attractive neutron properties. Thus the Doppler coefficient is about -1,40 particles cm/°that provides a truly safe mode active zone of the nuclear reactor after a sudden power increase, causing an increase in the fuel temperature.

Similarly, the ratio of delayed neutrons (β_eff) is 364 particles per cm, which provides a good supply of reactor control after the premature withdrawal of the control device. This positive phenomenon highlights the significant tensile fracture and a relatively high melting point of some is that of metal-ceramic materials.

In addition, the reactivity coefficient is approximately 1,467 for the new active zone of the nuclear reactor (infinite medium). Considering the power per unit mass released by fuel (approximately 88 W/g heavy nuclei), it becomes possible to achieve a very long cycles and, in particular, to obtain the rate of combustion of fuel in a nuclear reactor during unloading, close to 100 GW. day/ton (equivalent UO₂).

For the same assumptions, table 1 contains the original composition in heavy nuclei active zone of the nuclear reactor, corresponding to the considered example, the final composition of the active area of the power per unit volume equal to 195 mW/m³(which corresponds to the first example of the reactor CO₂described above), and rate of combustion of fuel during unloading, equal to 125 GW. night/so In this table, the values of the masses, expressed in kg, were calculated for the size of the active zone above as example (18 m³).

Table 1 shows that the content of fissile plutonium at the end of the cycle is still high (approximately 50%). This means that additional processing of plutonium would be possible to obtain download with the use of enriched solid media type UOX (uranium oxide fuel (MOX) and allows to use plutonium.

In addition, although the consumption of plutonium is not the main aim of the present invention, it should be noted that the used fraction (34%) will be higher than for a reactor that runs on water under pressure with 30% fuel type MOX (mixed oxide fuel), in which it is limited to approximately 25%.

It should also be noted that the original composition of the fuel can be optimized to improve the consumption of plutonium. However, this type of fuel has a major advantage in that it greatly consumed uranium 238 (down to level out the sustained fashion 30%). This provides a significant economic value for this fuel material, which is available in very large quantities.

Nuclear gas-cooled reactor, in which the active area consists of a fuel cell in accordance with the present invention is controlled by the input plates of boron carbide between the fuel elements. Given the spectrum of fast neutrons coming out of the reactor core, the absorption of heavy isotopes is low and is very limited individual contributions to the neutron balance. On the other hand, boron has a very high rate of local absorption and therefore very effective. In this energy range its effective cross section will be in the same order as that of the fuel isotopes, but its concentration is more than 50 times higher. Therefore, the input plates of boron carbide for each fuel element will be sufficient to ensure the multiplication factor (infinite k) with a value of less than 0,925.

Calculations were also performed based on the fuel composition and a half plutonium content in comparison with the previous example. This assumption is intended to reduce the limitations associated with the manufacture of fuel elements with high plutonium content.

The above calculations show that turns an attractive permanent the efficiency of the cycle (approximately three times in 18 months). In addition, since the initial reactivity is lower, may be provided with a simpler management of such fuel. Lower the amount of plutonium and higher amount of uranium 238 allow you to get the best Doppler coefficient and the best value for delayed neutrons. Moreover, the consumption of uranium 238 is lower than in the previous case, and variations of plutonium-239 will be practically zero.

Other calculations were performed for two examples in the fuel composition mentioned above, assuming that the power per unit volume is 319 MW/m³(which corresponds to the second example of the reactor, cooled CO₂above).

In both cases, increased power density leads to decrease cycle time. However, the resulting cycle is still very long. With three cycle lasting approximately 30 months, get fuel, containing 8% by volume of plutonium oxide, or three 12-month cycle can be obtained using the fuel containing 5% by volume of plutonium oxide.

In addition, the increase in power has virtually no effect on the percentage consumption of plutonium and uranium at high plutonium content. However, when increasing the power production side of actinides will be somewhat lower.

In the case of fuels with a low content of plutonium on the use of uranium 238 and plutonium 239 will be much more effective at increasing capacity per unit volume.

Obviously, the fuel elements in accordance with the present invention can be used in active zones in the form of a parallelepiped or in active zones of cylindrical or other shape. As mentioned above, the shape of each fuel cell may differ from the form described in particular with reference to figure 1.

1. The fuel cell (10) for the active zone of the nuclear reactor with a gas cooler, characterized in that it contains a lot of fuel plates (12A, 12b)arranged adjacent to each other, including elementary fissile particles embedded in a metal matrix, while the adjacent fuel plates (12A, 12b) are of the form and set relative to each other that form a multitude of channels (14) for the flow of gaseous refrigerant.

2. The fuel cell according to claim 1, characterized in that the channels (14) for the flow of gaseous coolant are essentially parallel to each other.

3. The fuel cell according to any one of the preceding paragraphs, characterized in that the fuel plates (12A, 12b) are continuous over the entire height of the reactor core and the channels (14) are located essentially in the vertical direction.

4. The fuel cell according to any one of the preceding paragraphs, characterized in that the channels (14) are essentially uniform cross-section throughout their length.

5. Topley is element according to any one of claims 1 to 3, characterized in that the cross-section of the channels (14) is modified so that each of these channels has a narrowed entrance portion and extending outlet section along the flow direction of the gaseous refrigerant.

6. The fuel cell according to any one of the preceding paragraphs, characterized in that the elementary fissile particles and reproducing substance introduced directly into the metal matrix.

7. The fuel cell according to claim 6, characterized in that each fuel plate (12A, 12b) includes a metal coating on each of its sides.

8. The fuel cell according to any one of claims 1 to 5, characterized in that the elementary fissile particles contain a coating of fissile and fertile substances and embedded in a metal matrix.

9. The fuel cell according to any one of p-8, characterized in that the fissile substance selected from the group consisting of uranium, plutonium and thorium.

10. The fuel cell according to any one of the preceding paragraphs, characterized in that the said fuel plates include a first plate (10A)positioned essentially parallel to each other, and the second corrugated plate (10b), and the first plates and second plates are mounted alternately.

11. A nuclear reactor containing the active area, formed from the fuel cell (10) according to any one of the preceding paragraphs, when this flux is of neutrons in the core of a nuclear reactor, in essence, represents a flux of fast neutrons.

12. Nuclear reactor according to claim 11, characterized in that the gas refrigerant is selected from the group consisting of carbon dioxide CO₂, helium, air, and argon.

13. A nuclear reactor according to any one of claim 11 or 12, characterized in that the control device on the basis of boron carbide In₄With inserted between the fuel cell (10).