RU2238597C1 - Method for nuclear-to-heat energy conversion - Google Patents

Abstract

FIELD: nuclear power engineering; nuclear-to-heat energy conversion for power plants of new generation.

SUBSTANCE: proposed method for energy generation from nuclear fuel involves commencement of cascaded nuclear processes by relativistic beam of protons conveyed to target in reactor core. Used as neutron-producing target is reactor core fuel in the form of materials including heavy nuclei affording positive energy yield in the course of fission reaction. Energy of protons should satisfy condition of sufficiency for producing secondary particles of reaction between proton and heavy nuclei whose mean energy exceeds 14 MeV. Fuel used for the purpose is thorium, uranium-238, bismuth, lead, or composition thereof.

EFFECT: elimination of long-living radioactive materials in reactor core.

2 cl

Description

The invention relates to the field of nuclear energy, and in particular to technology for converting nuclear energy into thermal energy, designed to create power plants.

Known methods of converting nuclear energy into thermal energy, using elements of heavy radium as nuclear fuel. Existing reactor plants generate energy using this method of converting nuclear energy into thermal energy. The fission of nuclei in these reactors is carried out by either thermal or fast neutrons (the neutron energy in these ranges does not exceed 14 megaelectron-volts). Brief Encyclopedia “Atomic Energy”, Executive Editor B.C. Emelyanov, State Scientific Publishing House “BSE”, 1958, p.541-545.

The main disadvantages of the existing technology for converting nuclear energy are due to:

- the production of a large amount of radioactive long-lived waste;

- the production of induced activity in the elements of the reactor and the surrounding structures;

- the presence of a stock of positive reactivity;

- the production of substances that could potentially be used for nuclear terrorism;

- a relatively short time.

The closest analogue to the proposed invention is a method of generating energy from nuclear fuel, which consists in the excitation of nuclear cascade processes by a relativistic proton beam directed to the target in the reactor core (RU 2178209, MPK7 G 21 C 1/00). According to this method, a beam of high energy particles is sent to a chamber for producing high energy neutrons. The resulting neutrons are propagated under subcritical conditions using the reproduction and fission process, which is carried out inside the chamber. The neutron energy in this method also does not exceed an average energy of 14 megaelectron-volts. This patent describes an installation of an electronuclear type, in which a special target irradiated by a high-energy proton beam is used as a neutron source. Further neutrons are sent to the core. The fundamental thing in this process is that the neutron production target in this case is separated from the nuclear fuel zone, which is called the blank. The use of this technology for generating energy from nuclear fuel in reactor plants eliminates a number of significant drawbacks of existing plants, in particular, the operation of the electron-nuclear-type plants does not require a reserve of positive reactivity of the reactor core. However, these reactors will be the sources of all groups of radioactive waste produced by modern facilities. This drawback is the main one.

A known method of irradiating directly the fuel of the reactor core with a proton beam (“Technological aspects of nuclear energy systems with fuel reproduction”, Moscow, Energoatomizdat, 1988, p. 190). But in this method, the fuel located in the fuel element was irradiated. At the same time, the fuel was not a single array, but was delimited by a moderator. This circumstance fundamentally affected the energy spectrum of secondary particles formed as a result of the interaction of a proton and a heavy nucleus.

The presence of positive reactivity and the separation of the reactor core and coolant in modern reactors led to the use of complex control and protection systems, which significantly complicates the design of the reactor and requires expensive measures to ensure the reliability of the reactor. In addition, the decommissioning of these reactors is very acute. To date, it has not been resolved.

The problem to which the present invention is directed, is the development of a method that eliminates the above disadvantages, in particular:

- production of a large amount of radioactive long-lived waste;

- production of induced activity in reactor elements and surrounding structures;

- the production of substances that could potentially be used for nuclear terrorism;

- elimination of complex reactor control and protection systems;

- increase the life of the reactor installation.

The technical result consists in eliminating the production of long-lived radioactive materials in the reactor core due to the use of substances having heavy nuclei as nuclear fuel in reactors, the fission of which is accompanied by the release of positive energy and producing fission of these nuclei of elementary particles having an average energy in the range high energies (more than 14 megaelectron-volts). The reactor core is fundamentally subcritical.

To achieve a technical result in the method of converting nuclear energy into thermal energy, which consists in exciting nuclear cascade processes by a relativistic proton beam directed to the target in the reactor core, the reactor core fuel is used directly as the target for producing neutrons, substances are used as fuel, having heavy nuclei giving a positive energy yield in the fission reaction, while the proton energy must satisfy the sufficiency condition for the production of secondary reaction particles, the proton is a heavy nucleus, the average energy of which exceeds 14 megaelectron-volts.

In addition, it is advisable to use thorium, uranium-238, bismuth, lead or compositions of these substances as fuel.

It is possible to clarify the energy range in which secondary particles should be located. The maximum fission cross section for protons and neutrons is in the energy range 18–40 MeV (Prokofiev Nucl. Instr. A 463 (2001, 557-575).

In the proposed energy production technology, fission of nuclei is caused by secondary particles, on average, having energies significantly exceeding the energy of neutrons used in conventional reactors. According to the accepted classification (reference book “Physical quantities” // Edited by I.S. Grigoriev, E.Z. Meilikhov) neutrons belong to the group of high-energy particles, i.e. energy greater than 14 MeV. Elementary particles of this energy in modern reactors are formed during fission reactions, only in very small quantities. As a fuel, in principle, all heavy nuclei can be used, which give a positive energy yield during fission. But it is most expedient to use thorium, uranium-238, bismuth or lead, or compositions of these substances as fuel.

These features characterizing the method of generating energy from nuclear fuel are essential and interconnected causally with the formation of a set of essential features sufficient to achieve a technical result.

The invention consists in the following.

According to the invention, a method for converting nuclear energy into thermal energy consists in exciting nuclear cascade processes by a relativistic proton beam directed to the reactor core.

The fuel for the reactor core, which is a continuous array, is used directly as a target for the production of secondary particles, and substances having heavy nuclei that give a positive energy yield during the fission reaction are used as fuel. In this case, the proton energy should be sufficient for the production of secondary particles with an energy greater than 14 MeV on average.

It is advisable to evenly distribute fuel in the reactor core over the entire space of the core.

In this case, it is advisable to combine the functions of fuel and coolant in the reactor core, in which quality, in some cases, it is possible to use the same substance.

The proposed method for generating energy from nuclear fuel is based on the use of substances having heavy nuclei as a nuclear fuel in reactors that give a positive energy yield in the fission reaction. This possibility is based on the fact that during the fission of all substances with an atomic mass of more than 60, additional energy is released. So, for example, during the fission of thorium, about 190 MeV of additional energy is released. In the division of lead or bismuth, an average of about 140-150 MeV of additional energy is released. However, the threshold value of the fission reaction of these substances significantly exceeds the similar values for conventional nuclear fuel. So for thorium it is 6 MeV, and for lead - 25 MeV. In this regard, the initiation of such reactions requires secondary particles with an energy of at least higher than the corresponding threshold values. Such particles can be obtained, for example, by the interaction of a proton beam of sufficiently high energy obtained at the accelerator, directly with the substance used in the reactor core. The interaction of a proton beam with atoms of condensed matter leads to the formation of a shower of elementary particles, in particular neutrons, protons, and fragments of bombarded nuclei. The energy of the secondary particles is largely dependent on the energy of the incident proton. If the incident particle energy exceeds the threshold fission energy of the core material, the nuclei of the latter (substance) can share with the release of additional energy. In this case, the probability of fission increases with increasing particle energy. The fragmentation of heavy nuclei is deeper. Much more frequent splitting with the formation of 3 or more fragments.

The present invention is illustrated by specific examples of implementation, which, however, are not the only possible, but clearly demonstrate the ability to achieve this set of essential features of a given technical result.

Example 1

The target, which was also a model of the reactor core, was an assembly of 800 × 500 × 500 cm ^{3 in} size, uniformly filled with lead. The target was bombarded by a stream of protons with an energy of 5 GeV. Moreover, the average energy of secondary particles, including neutrons, was about 25 MeV. As a result of the experiment, energy release was detected in the lead assembly, exceeding the energy supplied to the assembly with the proton beam.

Example 2

In November 2002, an experiment was performed at the Protvino accelerator to interact with a proton beam with an energy in the range of 6 to 20 GeV with a large lead target, including bismuth fragments. During the experiment, the activity of the lead assembly was increased to 8 x-rays per hour. After 2 days, the activity decreased to 2 ml X-ray per hour, and after 10 days to the background level.

The application of the invention allows to obtain advantages over the well-known, which are that:

- long-lived fission products are not produced in the reactor core, which greatly simplifies the task of processing radioactive waste and excludes the possibility of using reaction products for terrorist purposes;

- the reactor core is aligned with the target for the proton beam, which greatly simplifies the design of the reactor. The use of metallic substances as a coolant and working fluid sharply increases the service life of reactor equipment and the efficiency of the entire reactor facility as a whole. In addition, the technology of decommissioning the reactor installation is simplified;

- since the substances proposed for use as fuel do not form a critical mass, there is no need for control and protection systems;

- the functions of the source of thermal energy and coolant can be combined.

The invention meets the condition of patentability “industrial applicability”, since its implementation is possible using existing means of production using known technological operations.

Claims (2)

1. A method of converting nuclear energy into thermal energy, which consists in exciting nuclear cascade processes by a relativistic proton beam directed to a target in the reactor core, characterized in that the reactor’s core fuel is used directly as a target for producing neutrons, and substances are used as fuel having heavy nuclei giving a positive energy yield during the fission reaction, while the proton energy must satisfy the sufficiency condition for the production of watts The proton reaction particles are a heavy nucleus, the average energy of which exceeds 14 MeV. 2. The method according to claim 1, characterized in that the fuel used is thorium, uranium-238, bismuth, lead, or compositions of these substances.