阅读说明：本技术 一种核反应堆长寿期中子源装置及使用方法 (Nuclear reactor long-life neutron source device and using method thereof ) 是由 杨庆湘 郭建 杨波 汤春桃 王梦琪 毕光文 王丽华 黎辉 秦玉龙 丁谦学 于 2021-03-25 设计创作，主要内容包括：本发明公开了一种核反应堆长寿期中子源装置及使用方法,所述装置包括可密封安装长寿期中子源的中子源组件,所述中子源组件与反应堆控制棒驱动机构相连接,所述中子源组件通过所述反应堆控制棒驱动机构插入或提出反应堆堆芯；所述长寿期中子源可选择镅铍源或钚铍源。本发明可以显著降低中子源材料在反应堆运行时的消耗,保持中子源材料的长寿期特性,因而可以一个或多个机组重复使用,从而避免国内每个新建核动力厂机组都有面临一次中子源材料采购的工程造价和工程进度不确定性。(The invention discloses a nuclear reactor long-life neutron source device and a using method thereof, wherein the device comprises a neutron source assembly which can be used for sealing and installing a long-life neutron source, the neutron source assembly is connected with a reactor control rod driving mechanism, and the neutron source assembly is inserted into or pulled out of a reactor core through the reactor control rod driving mechanism; the longevity neutron source can be selected from an americium beryllium source or a plutonium beryllium source. The invention can obviously reduce the consumption of neutron source materials during the operation of the reactor and maintain the long-life characteristics of the neutron source materials, thereby being capable of repeatedly using one or more units, and avoiding the construction cost and the uncertainty of the construction progress of each newly built nuclear power plant unit facing one-time purchase of the neutron source materials in China.)

1. A nuclear reactor long-life neutron source device is characterized by comprising a neutron source assembly for sealing and installing a long-life neutron source, wherein the neutron source assembly is connected with a reactor control rod driving mechanism and is inserted into or pulled out of a reactor core through the reactor control rod driving mechanism; the longevity neutron source comprises an americium beryllium source or a plutonium beryllium source.

2. A nuclear reactor long-life neutron source device as claimed in claim 1, wherein said long-life neutron source passes through separately²⁴¹Am and²³⁸bombardment of alpha particles produced upon alpha decay of Pu⁹Be emits neutrons.

3. A method of using the nuclear reactor longevity neutron source device of claim 1, wherein the longevity neutron source is hermetically encapsulated within the neutron source assembly, the neutron source assembly being connected to the reactor control rod drive mechanism;

when the reactor is started: the neutron source component is inserted into the reactor core through the reactor control rod driving mechanism, and the reactor control rod driving mechanism lifts the neutron source component out of the reactor core after the count rate detected by the out-of-reactor detector is normal.

4. The method of claim 3, wherein the neutron source module is discharged from the reactor core and then used for starting a reactor in a subsequent cycle of the same unit or starting a reactor in another unit.

Technical Field

The invention belongs to the technical field of nuclear reactor fuel, and particularly relates to the technical field of a reactor neutron source.

Background

In domestic operation and pressurized water reactor nuclear power plants under construction, two starting modes of an external neutron source and no external neutron source exist, except that the pressurized water reactor designed in Russia is designed according to the starting design of no external neutron source, and all other pressurized water reactor nuclear power plants designed in China, America or France are designed according to the starting design of an external neutron source.

For the reactor design with the external neutron source, the neutron source is used for providing a basic neutron counting level in the process of loading the reactor to be critical so as to ensure that the source range detector can normally operate and respond to reactor core breeder neutrons, overcome the blind area of the source range detector, ensure that the reactor has enough neutron counting rate in a subcritical state to carry out critical safety supervision and ensure the safe starting of the reactor. The primary neutron source (also called as a primary neutron source) is made of a material capable of emitting neutrons, is used for the first start of a nuclear power plant, and is discharged out of a reactor core after the primary neutron source is recycled for the first time and is not used any more; the secondary neutron source (also called secondary neutron source) generally adopts an antimony-beryllium (Sb-Be) source, does not emit neutrons when not irradiated, is put into a pile when the material is firstly circularly charged, and is used for the second and subsequent circulations after being irradiated and activated in the pile.

The primary neutron source used in the current nuclear power plant is a nuclide capable of emitting neutrons through spontaneous fission, a californium source is mostly adopted, and the nuclide capable of emitting neutrons through spontaneous fission utilizes²⁵²Cf, this species. In recent years, several disadvantages have been highlighted with this neutron source:

1)²⁵²the half-life of Cf is about 2.635 years, and can be generally used for starting only one unit;

2)²⁵²cf production relies on ultra high flux reactorsDomestic production conditions are not available;

3)²⁵²the Cf international purchase cost is continuously increased, so that the construction cost of the nuclear power plant is increased;

4) affected by international situation, and Russia²⁵²Cf Capacity shrinkage effects, difficult to guarantee²⁵²The sufficiency and the progress of supply of the Cf neutron source bring uncertainty to the construction project progress of a nuclear power plant.

At present, most nuclear power plants in China adopt a reactor design with an external neutron source, and the common problem of primary neutron source supply still faced by domestic mainstream pressurized water reactor models such as CAP1400, CAP1000, Hualong I and CPR1000 is expected to be solved for a long time, and the reactor design is also one of the neck clamping problems still existing in the autonomous nuclear power technology construction and export in China.

In order to solve the problem of primary neutron source supply, the invention provides a method for manufacturing a long-life neutron source by utilizing a neutron source material with a long half-life period, and the long-life neutron source can be recycled at first in a plurality of nuclear power plant units. After the technology is adopted, the domestic newly-built nuclear power unit does not depend on purchasing from foreign countries for a long time²⁵²Cf, the aim of reducing the construction cost and ensuring the construction progress is achieved.

Disclosure of Invention

The invention aims to provide a long-life neutron source device capable of being repeatedly used in a nuclear power plant and a using method thereof, which can eliminate long-term dependence on a domestic supply neutron source material, reduce the construction cost of nuclear power construction engineering and ensure the progress of engineering construction.

In order to achieve the aim, the invention provides a nuclear reactor long-life neutron source device, which comprises a neutron source assembly for sealing and installing a long-life neutron source, wherein the neutron source assembly is connected with a reactor control rod driving mechanism and is inserted into or pulled out of a reactor core through the reactor control rod driving mechanism; the longevity neutron source can be selected from an americium beryllium source or a plutonium beryllium source.

Preferably, the long-life neutron sources respectively pass through²⁴¹Am and²³⁸bombardment of alpha particles produced upon alpha decay of Pu⁹Be andneutrons are emitted.

The invention also provides a use method of the nuclear reactor long-life neutron source device, wherein the long-life neutron source is hermetically packaged in the neutron source component, and the neutron source component is connected with the reactor control rod driving mechanism;

when the reactor is started: the neutron source component is inserted into the reactor core through the reactor control rod driving mechanism, and the reactor control rod driving mechanism lifts the neutron source component out of the reactor core after the count rate detected by the out-of-reactor detector is normal.

Preferably, the neutron source assembly can be used for starting a reactor of a subsequent cycle of the same unit or starting a reactor of other units after being discharged out of the reactor core.

Compared with the prior art, the invention has the following advantages:

1. the use mode of the invention can obviously reduce the consumption of the neutron source material when the reactor operates, and maintain the long-life characteristic of the neutron source material, so that one or more units can be repeatedly used, thereby avoiding the construction cost and the uncertainty of the construction progress of each newly built nuclear power plant unit facing one-time purchase of the neutron source material in China.

2. The use mode of the invention is easy to realize in the existing reactor design, such as inserting and extracting a neutron source by using a control rod driving mechanism, and has small requirement on changing the original design.

3. And commonly used²⁵²Cf is generally easier to manufacture than the neutron source materials used in the present invention.

Drawings

FIG. 1 is a schematic illustration of the insertion of a neutron source assembly into a core;

FIG. 2 is a schematic illustration of a core for a neutron source assembly.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

The invention provides a method for reusing a long-life neutron source in a nuclear power plant, which comprises the long-life neutron source, a neutron source assembly connected with a reactor control rod driving mechanism and an operation mode of the neutron source in a nuclear power plant reactor.

As a preferred embodiment of the invention, the neutron emitting material of the long-life neutron source can be selected from an americium beryllium source or a plutonium beryllium source, and the americium beryllium source or the plutonium beryllium source respectively passes through²⁴¹Am and²³⁸bombardment of alpha particles produced upon alpha decay of Pu⁹Be emits neutrons. In the absence of external irradiation conditions,²⁴¹am and²³⁸both Pu nuclides mainly disappear through alpha decay, the half-life periods of the two nuclides are 433 years and 86 years respectively, and the two nuclides can meet the strength requirement of a neutron source for starting a reactor within decades.

In order to avoid the situation that the neutron emitting material of the long-life neutron source can be consumed due to the high neutron fluence rate environment in the reactor operating environment, the neutron source assembly is moved out of the reactor core fuel active area after the reactor is started and before the power is increased, so that the consumption level is obviously reduced.

After the reactor is shut down, the long-life neutron source can be continuously used as a neutron source for subsequent starting of the same unit, and can also be transferred to other units to be used as starting neutron sources, so that the reutilization is realized.

Preferred neutron emitting materials of the present invention are produced by high-throughput irradiation with far less difficulty than²⁵²Cf is widely used in domestic and foreign industries, and has a certain reserve amount in domestic and foreign nuclear industry systems due to long half-life period, so that the Cf is beneficial to being applied to a nuclear power plant in terms of manufacturing cost and schedule requirements of preparation.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The foregoing examples or embodiments are merely illustrative of the present invention, which may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.