RU2328049C1 - Process of crashed atomic reactor entombment - Google Patents

Abstract

FIELD: physics; construction.

SUBSTANCE: process of crashed atomic reactor entombment includes construction of underground mortuary in the form of vertical underground excavation. Internal volume of the excavation is filled with ice which forms a new temporary ice foundation under the basis of the crashed reactor. The weight of the latter is shifted to the new ice foundation, heat is conducted to it, and gradually the height of ice foundation is decreasing till the complete removal of ice. At that, the crashed reactor is set at the mortuary made previously at the basement of excavation. Before deposition of the crashed reactor underground, solidity (thickness) of frozen soil body under the reactor basis is improved, and then, after the new ice foundation is ready, the load is increased, and the previous ground base is destroyed by adjoining of excavation ice body to the crashed reactor basis via flexible load-bearing cables laid through the vertical wells.

EFFECT: reduces amount of work in immediate proximity to a crashed atomic reactor.

Description

The invention relates to special construction, namely, the technology for the disposal of emergency reactors such as the fourth unit of the Chernobyl nuclear power plant and other environmentally hazardous facilities.

The experience of eliminating the consequences of the accident at the Chernobyl (USSR) and Three Mile Island (USA) nuclear power plants, as well as the disposal of nuclear blocks of nuclear power plants that have exhausted their resources, indicates the absence of effective ways to solve such problems. The costs of dismantling not even accidental, but only exhausted nuclear reactors exceed the cost of their construction [1, 3].

Currently, it is believed that the most rational way to localize the consequences of major accidents at nuclear power plants can be achieved by creating a special shelter in the form of a protective shell over the emergency reactor. Such a temporary shelter - the "sarcophagus" - over the fourth block of the Chernobyl nuclear power plant was built in five and a half months and put into operation by November 1986. Currently, this "sarcophagus" is in disrepair, which is explained not only by the shocking pace of construction, but also by the specific conditions of its creation. Due to the high radiation, the installation of structures was carried out remotely using television installations. All nodes, all joints excluded welding and precise fixation. Most of the supporting structures of the "sarcophagus" were forced to rely on surviving pillars, the strength of which in many cases could not be reliably determined. There was no serious control over the quality of installation. For these reasons, the structure was not sealed, the total area of various kinds of slots and openings exceeded a thousand square meters. Atmospheric moisture, getting inside the "sarcophagus, connected, for example, with boron carbide, created an acidic environment, which significantly accelerated the corrosion rate of steel structures, including beams and supports. Therefore, the service life of the "sarcophagus" at the design stage was limited to 30 years.

Thus, the warranty period of the existing "sarcophagus" ends. The collapse of this "shelter", according to experts, can lead to even more serious consequences than the 1986 disaster. After all, the emergency unit still contains 95% of nuclear fuel, whose total activity is 19 million curies.

In connection with the above, the question of the need to create a new shelter over the existing "sarcophagus" became relevant in 1992. In the same year, an international project competition was announced to turn the Shelter Object into an environmentally friendly system. The West won (the French company Campenon Bernard), which Ukraine offered not only a technical solution, but supposedly money for its implementation of its project.

According to the French project, the new shelter - kanfaynment (NSC) - consisted of a protective sheath 108 m high, 275 m long and 150 m wide. To reduce the radiation doses for builders, this grandiose structure should be created near the fourth power unit, then pulled over to the old "sarcophagus" .

After determining the cost of the French project, from 1 to 4 billion dollars, the West refused to finance this work.

Approximately the same amount is currently estimated at the cost of dismantling and liquidating existing operating nuclear power plants after they have exhausted their resources [1].

Thus, the disadvantage of the known methods is not only the insignificant life of the ground "sarcophagi", not only their extremely high cost, but, and most importantly, the high doses of radiation that workers will inevitably receive during the construction of such a structure.

The closest in technical essence to the claimed device is the "Method of disposal of environmentally hazardous objects" [2]. The specified method involves the creation of an underground repository in practically watertight soils, followed by moving there, for example, an emergency reactor and the removal of heat, which is formed as a result of fission of atomic nuclei of fissile substances. To do this, at a safe distance from the emergency reactor, a vertical barrel and horizontal adits are made to the center of this reactor. Sources of cold and heat are installed in the galleries, the soil under the foundation of the emergency reactor is pre-fixed by drilling deviated wells, installing thick-walled casing pipes in them and freezing this soil using a cold source, for example liquid nitrogen, the boiling point of which is minus 196 ° С. Then, coaxially with the emergency reactor, above the adit, an underground vertical mine is created, secured by a lining, inside which heat exchangers are attached to the indicated sources of heat and cold, then they fill the internal volume of the mine with water and, cooling it, turn water into ice. Then the soil immediately under the emergency reactor is thawed, casing pipes are removed from deviated wells and vertical wells are drilled to ice along the perimeter of the emergency reactor. In this case, the weight of the reactor is transferred to a specially created ice foundation. Then, the coolant supply is stopped and the coolant is supplied to the heat exchangers of the vertical generation base. As the ice melts, the height of the ice foundation decreases - the emergency reactor is lowered vertically into an underground repository. The resulting water is removed.

This method has the disadvantages of all known methods for the disposal of emergency reactors, although to a much lesser extent, namely: the need to perform part of the work in the immediate vicinity of the radiation source - drilling many wells initially for fixing, then for destroying the base under the foundation of the emergency reactor. In this case, a major disaster can occur with the deaths of people in the underground vertical excavation, if the strength of the frozen soil is insufficient, then the emergency reactor will go underground, into the created vertical excavation prematurely, before the creation of the ice foundation.

To ensure the safety of operations when moving the emergency reactor underground, it is proposed to increase the strength (thickness) of the soil mass under the foundation of the emergency reactor before moving the emergency reactor underground, then, after creating the ice foundation, increase the load and destroy the previous soil base by connecting the ice underground mine workings to the foundation of the emergency reactor by means of flexible load-bearing links laid through vertical wells.

When implementing the proposed technical solution, when ice melts in an underground vertical mine, the weight of the ice mass is added to the weight of the emergency reactor, due to which the number of wells required to weaken the soil under the base of the emergency reactor can be significantly reduced. Accordingly, this will reduce the volume and cost of work in the immediate vicinity of the emergency nuclear reactor.

New in the claimed invention is the operation of installing flexible connections between the existing foundation of the emergency reactor and underground mining under it.

The invention is illustrated by the following example of a device that implements the claimed method (see drawing), which shows: emergency reactor 1, similar to the fourth unit of the Chernobyl nuclear power plant, and the same reactor in the final position 1a; deviated wells with thick-walled casing 2, designed to freeze the soil under the emergency reactor; located under the reactor and coaxially with it, underground vertical mine 3 with lining 4, inside of which heat exchangers 5 are located on the lateral surfaces, and heat exchangers 7 in the base 6. These same structures can serve as additional fittings that increase the strength of the lining of the underground mine.

Pipes with shut-off and control valves 8, 9 and 10 are provided for supplying coolant and coolant to the heat exchangers. A water conduit 11 is provided for supplying water to the production. The same water conduit is used to remove water from the underground water production after the ice has melted. For the same purposes, a pump 12 and shut-off and control valves 13-17 are provided. To obtain a coolant, a cold source (chiller) 18 is provided, and to obtain a coolant a heat source (boiler) 19 is provided. Liquid nitrogen can be used to freeze soil and water.

Construction and installation works are carried out through a special vertical shaft 20 and horizontal galleries (lost) 21 and 22. To loosen the connection between the reactor foundation and the surrounding soil, it is planned to drill vertical wells 23 through which flexible load-carrying connections (cable, chain) 24 are passed into the underground mine 3 connected at the top with the foundation of the reactor 1.

The proposed method is as follows. At a safe distance from the emergency reactor 1, a barrel 20 and horizontal adits 21 and 22 are built, suitable for the axis of the specified reactor. In one of the tunnels 22, a refrigeration machine 18 and a heat generator 19 are installed and the construction of the mine 3 is started. Preliminarily, in order to prematurely lower the emergency reactor 1 into the mine 3, inclined wells are drilled and thick-walled casing pipes 2 are installed in them and the soil is frozen directly with them under the foundation of emergency reactor 1, thereby increasing the stability of this foundation. For these purposes, liquid nitrogen should preferably be used.

As the mine 3 is drilled, a lining 4 with heat exchangers 5 is installed, as well as a lining of the base 6 with heat exchangers 7. The depth of the underground mine 3 should be not less than the height of the emergency reactor 1. In addition, the depth of the underground mine is determined by the hydrogeological conditions of the planting site: a repository, where emergency reactor 1 should be stored for hundreds of years; as a rule, it should be located in weakly filtering soils, for example, in clays.

After the construction of mine 3, it is filled with water using a water conduit 11 (valves 14 and 16 are open; 13, 15 and 17 are closed). To ventilate the air and pass flexible load-bearing bearing links 24, several vertical wells are drilled 23. After the wells 3 are completely filled with water, the refrigeration machine 18 is turned on, and the coolant flows through the pipelines to the heat exchangers 5 and 7, while the water in the underground mine 3 turns into ice, flexible load-bearing connections 24 freeze into the ice mass of this mine. Thus, the emergency reactor 1 receives a new support in the form of an ice foundation. The formation of a new support allows you to weaken the old soil support. To do this, stop the flow of liquid nitrogen into thick-walled casing pipes of deviated wells 2, and instead of nitrogen, a coolant is fed into them to defrost and weaken the surrounding soil. Then the casing from the deviated wells 2 is removed. To further weaken the soil foundation under the emergency reactor 1, vertical wells 23 may be drilled. Next, turn off the refrigeration machine 18, turn on the heat generator 19 and supply the heat carrier to the heat exchangers 7 of the base 6. The heat exchangers 5 briefly supply coolant to eliminate ice adhesion to the side walls of the vertical generation 3.

As heat enters the base 6, the ice on its surface will melt, and the entire ice mass in underground mine 3 will begin to sink under its own weight. At the same time, the weight of this array through flexible load-bearing connections 24 will be transferred to the soil under the foundation of emergency reactor 1 and will violate the strength of this soil, after which the ice mass in mine 3 will become the new support of the emergency reactor. As the ice melts, the height of the new ice foundation will decrease and the emergency reactor 1 will slowly sink into the underground mine 3. The resulting water is removed through a water conduit 11 using a pump 12 (valves 13, 15 and 17 are open, and 14 and 16 are closed). After complete melting of the ice, the emergency reactor 1 becomes a new constant position 1a, where it is sealed, and if necessary, cooled using heat exchangers 5 and 7.

Using the inventive method for burying an emergency reactor, an ecologically safe system is obtained: radioactive radiation is reliably absorbed by the earth, the thickness of which can be almost any, the harmful effect on underground aquifers is limited by the presence of a hermetic lining of the underground mine 3 and the use of waterproofing waterproofing, mainly from clay.

The application of the claimed method allows to solve the largest scientific and technical problem of the world level.

Literature.

1. Matveev L.V., Rudik A.P. Almost everything about a nuclear reactor. - M .: Energoatomizdat, 1990 .-- 240 p.

2. RF patent No.2012079, cl. 5 G21F 9 / 24,1994.

3. Atomic energy, t.64, issue 4, 1988, s.248-254.

Claims (1)

A method for the burial of emergency nuclear reactors, including the creation of an underground repository under the emergency nuclear reactor, in the form of an underground vertical mine, filling the internal volume of this mine with ice and the formation of this new ice temporary base under the foundation of the emergency reactor, transferring the weight of the latter to a new ice base, supply heat and a gradual decrease in the height of the ice base, up to the complete removal of ice, while installing an emergency reactor on the base of the underground excavation dumps into a previously created burial ground, characterized in that when moving the emergency reactor underground, the strength (thickness) of the frozen soil mass under the foundation of the emergency reactor is previously increased, and then, after creating a new ice base, the load is increased and the old soil base is destroyed by connecting an underground ice mass working out to the foundation of the emergency reactor by means of flexible load-bearing connections laid through vertical wells.