RU2687054C1 - Nuclear reactor - Google Patents

Abstract

FIELD: nuclear physics and equipment.SUBSTANCE: invention relates to power engineering and can be used in designing nuclear reactor, mainly low power. Nuclear reactor comprises sealed housing partially filled with heat carrier and active zone immersed therein. Sealed housing above active zone is divided by horizontal partition into two cavities, interconnected by vertical bypass pipe, one end of which is connected to horizontal partition and the other one opens at level of core. Total volume of heat carrier does not exceed volume of lower cavity. On the surface of the horizontal partition wall there is a heat insulation. Heat exchangers of the first / second circuit are passed through the shaft with heat-insulated walls in the upper cavity and are located below the horizontal partition.EFFECT: reduced weight of structural material.3 cl, 1 dwg

Description

The invention relates to the field of energy and can be used to create a nuclear reactor, mainly low power for remote areas.

Known nuclear pool-type reactors, in which the biological protection function is performed by a thick layer of water (IA Chusov, AS Shelegov, O.Yu. Kochnov. Design features of water-in-water type research reactors. // Izvestiya Vuzov. - Yadernaya Energy. 2016. - № 3. - P. 116-126).

A disadvantage of the known devices is the possible release of water passing through the core and nitrogen-16 isotope activated directly onto the surface of the reactor pool, which leads to an unacceptable level of radiation dose in the reactor hall.

The closest in technical essence to the claimed device is a VGR-50 nuclear reactor (Grebennik VN, Kukharkin NE, Ponomarev-Stepnoy NN. High-temperature gas-cooled reactors - an innovative direction in the development of atomic energy. M .: Energoatomizdat, 2008 - 136 p.). The reactor contains a massive solid upper biological protection unit, placed in the upper part of the nuclear reactor vessel, made of neutron and gamma-absorbing material.

The disadvantage of this device is the large mass of the absorbing material, which complicates the transportation and installation of the reactor, and also increases the mass of the stored materials during the decommissioning of the reactor.

The authors faced the task of eliminating these shortcomings, namely the creation of an atomic reactor with a reduced mass of structural material.

To solve this problem in a nuclear reactor containing a sealed enclosure, partially filled with coolant, and an active zone immersed in it, the hermetic enclosure above the active zone is divided by a horizontal partition into two cavities connected by a vertical overflow pipe, one end of which is connected to a horizontal partition and the other opens at the level of the core, while the total volume of the coolant does not exceed the volume of the lower cavity. Thermal insulation is placed on the surface of the horizontal partition. The first / second circuit heat exchangers are passed through a shaft with heat-insulated walls in the upper cavity and are located below the horizontal partition.

The technical result is a reduction in the mass of structural material.

The invention is illustrated by the figures, in FIG. 1 is a schematic representation of the device. In the figure, the following reference designations are used: 1 — reactor vessel cover, 2 — reactor vessel beaker, 3 — horizontal partition, 4 — thermal insulation, 5 — upper cavity, 6 — lower cavity, 7 — overflow pipe, 8 — reactor basket, 9 — active zone, 10 - side reflector, 11 - thrusts of CPS organs, 12 - coolant level in the cold reactor, 13 - coolant level during reactor operation at power, 14 - heat exchanger.

A nuclear reactor contains a hermetically sealed reactor vessel comprising a reactor vessel lid 1 and a reactor vessel 2 tank connected by flanges through a horizontal partition 3 with thermal insulation 4. The horizontal partition 3 divides the reactor volume into two parts — the upper cavity 5 and the lower cavity 6. The cavities are interconnected vertical overflow pipe 7, the upper cut of which opens into the upper cavity 5 directly on the horizontal partition wall 3, and the lower cut into the lower cavity 6 at the level of the upper cut of the active zone 9, size At the level of the core 9, a side reflector 10 is placed. On the outer surface of the reactor basket 8, a side reflector 10 is placed. Control of reactivity of the reactor is carried out by control bodies, thrusts of control bodies 11 are passed through the upper cavity 5 and the reactor housing lid to the drives, located outside the reactor vessel. The reactor core 9 is filled with coolant, with the reactor stopped and cooled, the coolant level is set at 12, when the reactor is operating at power, the coolant partially flows into the upper cavity 5, filling it, and the lower cavity 6 sets the coolant level at 13. In the lower cavity 6 between the level of the coolant during operation of the reactor at the power 13 by thermal insulation 4 of the horizontal partition 3 heat exchangers 14 are placed to remove heat from the lower cavity 6 of the nuclear reactor vessel.

The device works as follows.

When the reactor is stopped and cooled down, the coolant flows into the lower cavity 6 and is installed at 12, with the coolant column performing the functions of biological protection against residual radioactive radiation of irradiated fuel. Since there are no short-lived radioactive impurities in the coolant, the height of the coolant column above the core is enough to reduce the dose load in the reactor hall to an acceptable level even if there is a thermoconvective transfer of the coolant to the level of the coolant surface in the cold reactor 12 due to the absence of its activation by the neutron flux in the active zone 9.

When the reactor is brought to power, activation of the coolant begins and its temperature rises. Taking into account the heat sink to the reactor chamber from the reactor vessel lid 1, it can be stated that the temperature in the upper cavity 5 is set at a lower level than in the lower cavity 6. Therefore, due to the difference in saturation pressures, the coolant from the lower cavity 6 is overloaded by the overflow pipe 7 cavity 5, while the coolant is taken from the lower part of the coolant path, with a low content of short-lived radioactive isotopes. As a result, a steam chamber is formed under the horizontal partition 3, in which radioactive steam condenses on the surface of heat exchangers 14, and a layer of unactivated coolant is located above the steam chamber and acts as a biological defense. In the event of an emergency associated with loss of coolant during reactor operation at power, there is a decrease in the level of coolant in the glass of the reactor vessel 2 without draining the coolant from the upper cavity 5, that is, the protective functions are preserved. When lowering the coolant level to the upper cut of the active zone 9, the lower end of the bypass pipe 7 is dried, the pressure in cavities 5 and 6 is leveled and the coolant flows into the lower cavity 6, preventing the fuel elements from drying and melting the active zone 9. thermal insulation

To reduce the flow of heat into the upper cavity 5 on the surface of the horizontal partition can be placed insulation 4.

To reduce the flow of heat into the upper cavity 5, the heat exchangers 14 can be passed through a shaft with insulated walls and placed below the horizontal partition 3.

A specific example of the device is a water-water boiling reactor with a vapor pressure of 16 atm, with a case diameter of 4 m and a height of 11 m. The wall thickness of stainless steel is 20 mm, the total weight of the case is 26 tons, which allows its transportation by any type of transport by two factory-made blocks - a reactor vessel cover and a reactor vessel beaker. The horizontal partition is made in the form of a disk with a thickness of 10 mm, sandwiched between the flanges of the reactor vessel lid and the reactor vessel glass. The overflow pipe is 100 × 2 stainless steel. The design of the core and fuel rods are similar to those of the VK-50 reactor. The mounting of fuel assemblies in the reactor basket is a lock in the base plate of the core. The heat carrier — water — is poured into the reactor vessel glass to a level below thermal insulation 4 by 20 cm. When the reactor reaches its nominal capacity, the water temperature in the lower volume rises to 200 ° C, the pressure rises to 16 atm and the water is squeezed from the lower cavity to the upper one. The height of the upper cavity is 2 m, which is enough to absorb ionizing radiation from radioactive steam under a horizontal partition.

In the proposed device, the function of the upper biological protection is performed by a layer of non-activated coolant and there is no solid protection against ionizing radiation, which significantly reduces the mass of the reactor. In addition, the water filling the upper cavity is an emergency reserve providing the function of passive protection of the core from melting in case of incidents associated with loss of the primary coolant. It should also be noted that the implementation of the technical solution does not lead to an increase in the dimensions of the reactor, since excess water flowing into the upper cavity when the reactor is operating at its capacity in the dampened state of the reactor occupies the volume of the vapor space with heat exchangers.

The use of the invention allows to reduce transportation costs, reduce installation time and reduce the amount of disposed radioactive materials during decommissioning.

List of positions

1 - reactor cover

2 - reactor vessel glass

3 - horizontal partition

4 - heat insulation

5 - upper cavity

6 - the lower cavity

7 - overflow pipe

8 - reactor basket

9 - active zone

10 - side reflector

11 - traction control organs

12 - the level of coolant in the cold reactor

13 - the level of coolant when the reactor is on power

14 - heat exchanger

Claims (3)

1. A nuclear reactor containing a sealed enclosure, partially filled with coolant, and an active zone immersed in it, characterized in that the sealed enclosure above the active zone is divided into two cavities by a horizontal partition, communicated by a vertical overflow pipe, one end of which is connected to a horizontal partition, and the other opens at the level of the core, while the total volume of the coolant does not exceed the volume of the lower cavity. 2. The device according to claim 1, characterized in that the insulation is placed on the surface of the horizontal partition. 3. The device according to PP. 1, 2, characterized in that the heat exchangers of the first / second circuit passed through the mine with insulated walls in the upper cavity and placed below the horizontal partition.

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