NUCLEAR REACTOR WITH A HEAVY LIQUID METAL COOLANT

Abstract

The invention relates to nuclear power engineering and is intended for using in power plants with a reactor with a heavy liquid metal coolant (HLMC) based on lead or on lead-bismuth alloys.

The invention makes it possible to increase the radiation protection efficiency for the in-vessel equipment of a nuclear reactor, to increase the heat storage capacity of the primary circuit, to reduce the nuclear reactor weight, and to improve its strength characteristics.

In the in-vessel space of a nuclear reactor, which is not occupied by the necessary equipment, containers filled with a material that reflects or absorbs neutrons, with a heat capacity greater than that of the coolant, are installed with gaps ensuring the coolant flow, while the containers are placed in such a way that the resulting gaps form channels with a turbulent coolant flow to cool these containers at a flow rate corresponding to the nominal power output level of the nuclear reactor.

Claims

1. A nuclear reactor with a heavy liquid metal coolant, with, located in the same vessel, at least one heat exchanger or at least one steam generator, control and monitoring elements, one circulation pump of the primary circuit, main channels and auxiliary channels, designed for the coolant flow, that do not perform the function of core cooling, including a header for collecting and distributing the coolant through the main and auxiliary channels, characterized in that in the in-vessel space of the nuclear reactor, not occupied by these elements, containers are placed with gaps, providing the coolant flow, wherein the said containers are filled with a material that reflects or absorbs neutrons, with a heat capacity greater than that of the coolant, wherein the said containers are placed in such a way that the resulting gaps form channels with a turbulent coolant flow for cooling these containers at its flow rate corresponding to the nominal power level of the nuclear reactor.

2. The nuclear reactor according to claim 1, characterized in that the containers are placed in such a way that the channels for the coolant flow formed between them are located preferably vertically.

3. The nuclear reactor according to claim 1, characterized in that boron carbide is used as a container filler.

4. The nuclear reactor according to claim 3, characterized in that the boron carbide in the containers is in the form of a vibro-compacted powder.

5. The nuclear reactor according to claim 3, characterized in that the boron carbide in the containers is in the form of hot-pressed blocks.

6. The nuclear reactor according to claim 3, characterized in that the boron carbide in one part of the containers is in the form of hot-pressed blocks, and in the other part it is in the form of a vibro-compacted powder.

7. The nuclear reactor according to claim 3, characterized in that materials based on hydrides of refractory metals are used as a filler in some of the containers.

8. The nuclear reactor according to claim 3, characterized in that steel is used as a filler in some of the containers.

9. The nuclear reactor according to claim 3, characterized in that inside the containers there is a free volume not filled by the filler.

10. The nuclear reactor according to claim 3, characterized in that the containers are equipped with plugs in which a filter is placed.

11. The nuclear reactor according to claim 10, characterized in that the plugs are made of a metal wire.

12. The nuclear reactor according to claim 1, characterized in that instead of containers, solid steel blocks are used while maintaining the external dimensions of the containers.

13. The nuclear reactor according to claim 1, characterized in that the containers are made in the form of bundles of rod containers.

14. The nuclear reactor according to claim 1, characterized in that the containers include internal cooling channels.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0061] FIG. 1 shows a 3D view of the reactor unit in accordance with the proposed technical solution.

[0062] FIG. 2 shows a 3D detail of the reactor unit view showing the coolant flow direction in the gaps between the blocks.

[0063] FIG. 3 shows vertical section 1-1 of the reactor unit along the pump and steam generator. In FIG. 3, the arrows show the coolant circulation pattern in the integral type reactor, the main feature of which is the placement of the core, a pump that ensures the coolant circulation, and a steam generator or a heat exchanger to remove the heat generated in the core, in the same vessel.

[0064] FIG. 4 shows a horizontal section of the reactor between the connecting pipes for supplying the coolant to the steam generator and the core.

[0065] FIG. 5 shows a detail of a load-bearing structure with blocks placed in it, made in the form of containers with boron carbide (A), as well as examples of possible solutions for choosing the container design (B-F). FIG. 5B shows a detail of the load-bearing structure with sections (the filler is not shown for clarity) and the movement of the elements (shown by the arrows). FIG. 5C shows the container bottom (the filler is not shown for clarity). FIG. 5D shows a block of smaller containers (the filler is not shown for clarity), which may replace the container shown in FIG. 5C. FIG. 5E shows a bundle of rod containers, which may replace box-type containers. FIG. 5F shows a container with internal cooling channels (the filler is not shown for clarity), which may replace groups of containers with external cooling.

EMBODIMENT OF THE INVENTION

[0066] The description of a possible, but not the only, option of the claimed invention is given below.

[0067] The reactor unit vessel (FIG. 3) includes a core 1 with a plug 2, a circulation pump 3, a heat exchanger 4, a pressure chamber 5, main channels 6, a lower chamber 7, an upper chamber 8, connecting pipes 9, and containers 10.

[0068] A heavy liquid metal coolant based on lead or lead-bismuth alloys is used as the coolant.

[0069] The containers 10 are located both in the low-temperature part of the primary circuit of the reactor and in the high-temperature part of the circuit.

[0070] The containers 10 are made of HLMC corrosion-resistant, high-temperature and heat-resistant austenitic steels.

[0071] The containers 10 fill the entire in-vessel space, except for the lowering channel of the pump 3 and the headers above and below the core 1. The containers 10 together with the shell 11 around the core 1 with the plug 2, the shell of the vessel 12, the radial ribs 13, and the annular horizontal ribs 14 form the load-bearing structure of the vessel. Holes for the coolant passage in the vertical direction are arranged in the annular horizontal ribs 14. The hole shape is selected so as to ensure the convenience of welding the load-bearing structure, the mounting of the blocks, and the uniform distribution of the coolant from the headers to the inlet of the vertically oriented slots. The holes can be of a cylindrical shape.

[0072] The dimensions of the gaps 15 (FIG. 2) between the containers 10 and the elements of the load-bearing structure are selected in such a way that, at a coolant flow rate corresponding to the nominal power level of the nuclear reactor, the flow is turbulent.

[0073] When choosing a specific design of the containers, including their volume, density, and filler material (steel or boron carbide in the form of denser hot-pressed blocks or less dense powder filling), the following factors are taken into account: [0074] The temperatures do not increase above the level, at which the compatibility of materials is ensured; [0075] The temperature of the block materials does not increase above the temperature of the coolant outlet from the core; [0076] The volume and weight of the block materials are sufficient to perform the radiation protection function for the vessel and the equipment located in it, as well as the secondary circuit coolant; [0077] The cross-sectional area for the coolant passage and the wetted perimeter of the blocks and elements of the load-bearing structure will be such that the turbulent flow of the coolant in the in-vessel space is ensured at a coolant flow rate corresponding to the nominal power output level of the nuclear reactor.

[0078] The fulfillment of the above mentioned criteria is verified by appropriate calculations made using known calculation methods.

[0079] A significant increase in speed in the gaps between the blocks above the turbulence limit is undesirable, since it results in an increase in the hydraulic resistance. A significant increase in the gap size with a decrease in the velocity and the transition to a laminar flow is also undesirable, since it impairs the heat transfer between the coolant and the containers.

[0080] During normal operation, the cold coolant is fed by the circulation pump 3 into the pressure chamber 5, from where it enters the inlet of the core 1 through channels 6. In the core 1, the coolant is heated and enters the volume above the core 1, and then enters the connecting pipes 9, which ensure the supply of the hot coolant to the steam generators or heat exchangers of the second circuit (the heat exchanger pipe system is not shown for clarity). FIG. 1 and FIG. 2 show that there can be several such heat exchangers with their corresponding connecting pipes. After entering the heat exchangers 4, the coolant is divided into two flows. Part of the coolant moving upwards is cooled by the secondary circuit coolant and enters the upper chamber 8. The part of the coolant moving downwards is also cooled by the secondary circuit coolant and enters the lower chamber 7, where it turns in the upward direction. When moving upwards, most of the coolant moves in the in-vessel space between the blocks 10 and eventually also enters the upper chamber 8. An insignificant part of the coolant from the lower chamber 7 enters into the gap between the vessel 12 and the shell 11 (see FIG. 3) to ensure temperature control of the reactor vessel. The ratio of the upward and downward flow rates of the heat exchanger is selected by calculation, so that the temperatures of the primary circuit coolant at the outlet of the two coolant flows from the heat exchanger 4 are approximately equal, taking into account their heating in the channels between the containers 10 and in the vessel temperature control channel.

[0081] The design of containers 10, based on the need to simultaneously achieve the key technical results, namely, forming the required composition of radiation protection, increasing the heat storage capacity of the primary circuit of the reactor unit, ensuring the required heat transfer to the elements performing the functions of a heat accumulator, and reducing the weight of the reactor unit, can vary as shown in FIG. 5.

[0082] Not only boron carbide can be used as a filler for the blocks, but other materials can also be used, if necessary. For example, known materials based on hydrides of refractory metals can be used instead of boron carbide to improve the neutron moderation in local areas. To improve the gamma radiation protection or increase the heat capacity, the container filler made of steel can be used, or a thin-walled container can be replaced with a solid steel block of the respective geometry. To improve the heat transfer between the coolant and the container, as well as taking into account the ease of installation or the technology of manufacturing containers of complex geometric shape, the containers can be enlarged with the formation of internal channels, as shown in the embodiments in FIG. 4.

[0083] The free volume of the containers 10 can communicate with the coolant volume through specially arranged plugs, in which a filter made, for example, of a metal wire, is installed, which prevents the ingress of boron carbide into the primary circuit. At the same time, the heat transfer between the coolant and the container materials is improved.

[0084] The described arrangement of the containers 10 inside the reactor vessel forms a coolant path through which the coolant passes when moving upwards from the lower chamber 7 to the upper chamber 8.

[0085] In the event of any type of accident resulting in deterioration of the heat removal from the core, a significant volume of blocks made of material with a heat capacity greater than that of the coolant performs the function of a heat accumulator. At the same time, the heat capacity of the blocks is higher than the heat capacity of the coolant displaced by them, which, in combination with the developed surface of the containers, slows down the temperature increase at the core inlet and contributes to an increase in safety. The vertical channels formed between the blocks and oriented in the direction corresponding to natural convection contribute to its rapid development in case of accidents with the shutdown of circulation pumps, which also contributes to an increase in safety.

INDUSTRIAL APPLICABILITY

[0086] The technical solution according to the invention can be used in power plants that use a reactor with a heavy liquid metal coolant (HLMC) based on lead or based on lead-bismuth alloys. The proposed nuclear reactor design provides a high degree of safety.