Method of transmutation of radioactive waste and the device for its implementation

 

The invention relates to nuclear energy, in particular the production of energy, transmutation of radioactive waste, burning weapons-grade plutonium and actinides. The technical result achieved by the invention is to improve the efficiency of the process of transmutation. For this purpose, the interaction of a beam of neutrons from the neutron generator is carried out on the lead matrix distributed in nuclear fuel and radioactive waste, then they slow down and multiply in a subcritical reactor core thermal neutrons. To accomplish this, the Central target device made in the form of a lead matrix distributed in nuclear fuel and radioactive waste. 2 S. p. f-crystals, 2 Il.

The invention relates to nuclear energy, in particular the production of energy, transmutation of radioactive waste, burning weapons-grade plutonium and actinides.

Known method of transmutation of radioactive waste, which consists in the use of high-energy nuclear reactions of fission and fission (M. Salvatores, I. Slesarev, M. Nematsu / A Global Physics Approach to Transmutation of Radioactive Nuclei. - Nuclear Science and Engineering, 116, 1994, 1).

The disadvantages of the method are: SL is the substance while transmutation can produce new radioactive nuclei; the expensive way, because its implementation requires nuclear particles to very high energies and correspondingly high power accelerators.

A device for the implementation of the transmutation of radioactive waste, which consists of heavy duty proton accelerator, the target of heavy elements, subcritical active zone of fissile nuclei, actinides and radioactive waste (Takakazu Takizuka et al. Dedicated accelerator-driven system for nuclear waste transmutation. / 3rdInternational Conference on Accelerator Driven Transmutation Technologies and Applications, June 7-11, 1999, Praha, Czech Republik).

The disadvantage of this device is its complexity due to the use of heavy duty proton accelerator, which makes it unreliable and reduces the effectiveness of transmutation.

The closest in technical essence to offer us is the way of transmutation of radioactive waste, consisting in the use of neutron flux resulting from the interaction of a beam of neutrons from a neutron generator with a lead target, the multiplication of neutrons in a subcritical reactor core thermal neutrons and absorption of radioactive waste (Serguei E. Chigrinov et"99), 1999, Praha, Czech Republic).

The disadvantage of this method is that the generation of neutrons is carried out on a lead target placed in the center of a subcritical reactor core thermal neutrons. Homogeneous target, while in a small solid angle, it is not possible to effectively use the neutrons coming out of the generator 4the geometry. As a result, the stream of generated and reproduced neutrons is lowered and has a thermal spectrum, and some radioactive waste is long-lived fission products and actinides have the highest cross-section of interaction only with the resonance and fast neutrons, which leads to reduced efficiency and speed transmutation of radioactive waste.

A device for the implementation of the transmutation of radioactive waste, including neutron generator, a casing, a Central lead target, surrounding the uranium-hydrogen-containing subcritical active zone of radioactive waste, radial reflector and biological protection (Serguei E. Chigrinov et al. A small-scale set-up for research of some aspects of accelerator driven transmutation technologies. / Proc. 3 Int. Conf. on Accelerator - Driven Transmutation Technologies and Applications (ADTTA"99), 1999, Praha, Czech Republic).

The disadvantage of this device is Inoi lead target that reduces the flow in the active zone and, as a consequence, the efficiency of transmutation. In addition, subcritical active area of the device slower and reproduction of neutrons generates a spectrum of thermal neutrons, which leads to a decrease in the rate of transmutation of radioactive waste.

The aim of the present invention is to provide a method of transmutation of radioactive waste, which would increase the efficiency of the process of transmutation in a subcritical reactor core.

The goal is solved in that in the method of transmutation of radioactive waste, which consists in obtaining the neutron flux resulting from the interaction of a beam of neutrons from a neutron generator with a lead target, reproducing them in a subcritical reactor core thermal neutrons and absorption of radioactive waste, according to the invention the interaction of a beam of neutrons from the generator is carried out on the lead matrix distributed in nuclear fuel and radioactive waste, then they slow down and multiply in politicheskoi active area on thermal neutrons.

The described method allows to increase the efficiency of transmutation of radioactive waste 1.5-1.8 times as compared the učka neutrons from the generator to the lead matrix with distributed it nuclear fuel, in which there is a simultaneous increase their flow and create a spectrum of fission neutrons. In the ambient thermal subcritical active zone is slow and multiplication of neutrons flowing from the Central zone. The placement of radioactive elements in the area of neutron spectrum, where they have the largest absorption cross-section, allows you to create optimal conditions transmutation and, consequently, to increase the efficiency of transmutation of radioactive waste by increasing the number of transmutable radioactive elements.

The proposed method can be implemented using the device for transmutation of radioactive waste, which includes a neutron generator, a casing, a Central lead matrix distributed in nuclear fuel and radioactive waste management, environmental impact of its uranium-hydrogen-containing subcritical active zone of radioactive waste, radial reflector and biological protection.

Such a device provides optimal conditions transmutation by irradiation of radioactive waste in it with fission spectrum neutrons and thermal spectrum.

In Fig.1 shows a perspective view of a device for transmutation of radioactive wastes, N. the mutation of radioactive waste contains a neutron generator 1, Central subcritical active zone on fast neutrons, consisting of the lead matrix 2, elements of nuclear fuel and radioactive waste management 3, subcritical active zone on thermal neutrons composed of hydrogenous moderator 4 and elements of the nuclear fuel and radioactive waste 5, the radial reflector 6, biological protection 7, neutron sensors 8 and the device 9.

Next, we consider the operation of this device, which will become clear and the essence of the claimed method.

The neutron beam from the generator 1 is supplied to the Central subcritical active zone on fast neutrons, consisting of the lead matrix 2 and item 3 containing nuclear fuel, such as enriched uranium, plutonium, and radioactive waste, the absorption cross section which in the spectrum of fission neutrons is large. On the lead matrix 2 is the secondary generation of fast neutrons, the flow of which is increased, and its spectrum is converted into a spectrum fission by interaction with nuclear fuel. The absorption of neutrons radioactive waste leads to turn them into non-radioactive, i.e. transmutation of radioactive waste. Emerging from the Central subcritical Akti is Rasem the retarder 4, for example, polyethylene, gerezani and so on, to thermal energy, multiply the result of the division of nuclear fuel 5 and absorbed radioactive waste having a high cross section for thermal neutron absorption.

Example of project proposed device for implementing the invented method of transmutation of radioactive waste.

The device comprises a neutron generator generating a neutron beam with an energy of 14.1 MeV, the intensity of 1,51012neutrons per second, and related sub-critical Assembly of the active zones of fast and thermal neutrons in a steel case.

Subcritical core fast neutron has the shape of a rectangular parallelepiped with a size of faces 480640640 mm and placed in the center of the subcritical Assembly in a steel casing that is associated with the outer housing ribs. Active area fast neutron recruited from a rectangular cassette size 7878640 mm, representing a lead matrix with uniformly distributed therein casing stainless steel tubes with a diameter of 101 mm and a length of 640 mm is these tubes are intended for elements with fuel and absorbing radioactive materials. Each cassette is placed in the casing of stainless steel size 8080640 mm and a wall thickness of 0.8 mm

On the radii 230, 120, 50 mm from the axis of the Assembly has end-to-end channels for the placement of the irradiated samples. Elements containing fuel and absorbing materials are sealed stainless steel tube with a diameter of 70.2 mm and a length of 620 mm, having a lower and upper limit switches length of 60 mm as fuel materials used nuclear fuel based on uranium-235, plutonium-239, 241, actinides, and as absorbing materials like strontium - 90, cesium-135, 137, iodine-129, and so on, the Height of the active part of the element - 500 mm

Active zone on fast neutrons surrounded by a subcritical active area on thermal neutrons, which consists of polyethylene blocks of size 808051 mm, collected in cassette length 510 mm In each of the blocks in a rectangular regular grid with a step of 20 mm has 16 holes with a diameter of 11 mm for placement of fuel elements of type EK-10, containing uranium dioxide, an enrichment of 10% uranium-235. Cassettes in two rows of closely adjacent to the casing active tonyh channels with a diameter of 25 mm to accommodate absorbing materials.

The active area on thermal neutrons surrounded by a neutron reflector in the form of a laying of tightly Packed plastic blocks, forming a layer thickness of 200 mm, completely filling the space between the active area and an outer housing Assembly.

Biological protection consists of slabs and blocks borrowing polyethylene thickness of 50 mm, is fixed on the surface of the outer case.

Thus, the proposed method of transmutation of radioactive waste and the device for its implementation will allow 1.5 - 1.8 times to increase the efficiency of conversion of neutrons radioactive waste into stable or short-lived isotopes.

Claims

1. Method of transmutation of radioactive waste, which consists in obtaining the neutron flux resulting from the interaction of a beam of neutrons from a neutron generator with a lead target, reproducing them in a subcritical reactor core thermal neutrons and absorption of radioactive waste, characterized in that the interaction of a beam of neutrons from the generator is carried out on the lead matrix distributed in nuclear fuel and radioactive waste, then they slow down and multiply in p is active waste includes a neutron generator, a casing, a Central lead target, surrounding its uranium-vodorodosoderzhashchego active zone of radioactive waste, radial reflector and biological protection, characterized in that the Central lead target made in the form of a lead matrix distributed in nuclear fuel and radioactive waste.

 

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