阅读说明：本技术 一种高价值控制棒中子吸收体材料 (High-value control rod neutron absorber material ) 是由 陈向阳 卢俊强 张兆泉 刘婵云 陈军 程熙月 范武刚 李聪 于 2019-12-03 设计创作，主要内容包括：本发明公开了一种高价值控制棒中子吸收体材料，该中子吸收体材料包括至少一种第一组分和至少一种第二组分，其中所述第一组分具有良好的中子吸收能力，所述第二组分与第一组分可形成稳定化合物；所述中子吸收体材料的初始反应性价值不低于Ag?In?Cd合金棒，且反应性价值随燃料组件燃耗变化率不快于Ag?In?Cd。本发明公开的中子吸收体材料的核物理性能优于常见商用吸收体材料，且显著提升了使用温度限值，提升了设计灵活性和堆芯安全性。(The invention discloses a high-value control rod neutron absorber material, which comprises at least one first component and at least one second component, wherein the first component has good neutron absorption capacity, and the second component and the first component can form a stable compound; the initial reactivity value of the neutron absorber material is not lower than that of the Ag-In-Cd alloy rod, and the reactivity value is not faster than that of Ag-In-Cd along with the burn-up change rate of the fuel assembly. The neutron absorber material disclosed by the invention has better nuclear physical properties than common commercial absorber materials, obviously improves the use temperature limit value, and improves the design flexibility and the reactor core safety.)

1. A high value control rod neutron absorber material comprising at least a first component having good neutron absorption capability and at least a second component capable of forming a stable compound with the first component; the initial reactivity value of the neutron absorber material is not lower than that of the Ag-In-Cd alloy rod, and the reactivity value is not faster than that of the Ag-In-Cd alloy rod along with the burn-up change rate of the fuel assembly.

2. The high value control rod neutron absorber material of claim 1, wherein the first component contains at least Dy: pure or substantially pure Dy metal, Dy alloy, Dy-based compound, or a mixture of the two Dy-containing materials mentioned above; the second component at least contains Al element: pure or substantially pure Al metal, Al alloys, Al-based compounds, and mixtures of the foregoing.

3. The high value control rod neutron absorber material of claim 2, wherein the first component Dy alloy does not contain halogen elements and elements that are susceptible to react with stainless steel to form intermetallic compounds, and the mass percent of Dy element is not less than 90%.

4. The high value control rod neutron absorber material of claim 2, wherein the second component Al alloy does not contain halogen elements and elements that are susceptible to react with stainless steel to form intermetallic compounds, and the mass percent of Al elements is not less than 90%.

5. The high-value control rod neutron absorber material according to claim 2, wherein the Dy-based compound of the first component may further comprise one or more of Gd, Tb, Tm, Sm, Eu, Cd, Ir, Lu, In, Nd, etc. In addition to Dy. The mass percent of Dy element is between 80 and 95 percent.

6. The high-value control rod neutron absorber material as claimed in claim 2, wherein the second component Al-based compound may further comprise one or more of Ga, Ti, Zr, Nb, Mo, Hf, Ta, W, Si, Ge, Sb, Te and the like besides Al, and the mass percentage of Al element is between 45-60%.

Technical Field

The invention relates to the technical field of nuclear materials, in particular to a neutron absorber material of a high-value control rod.

Background

The control rod assembly is a reactor control component that performs reactivity control of the core by insertion and extraction in the fuel assembly. Under normal working conditions, the reactor is used for starting, regulating reactor power and stopping, and under accident working conditions, the reactor quickly descends by means of self gravity, so that the reactor is emergently stopped in a very short time to ensure safety.

The primary absorber in the control rod assembly is the absorber material within the control rod, a currently common control rod neutron absorber material including boron carbide (B)₄C) Pellet (EP0364910A2, JP200221437A), hafnium (Hf) rod (US5742655A), silver-indium-cadmium (Ag-In-Cd) alloy rod (US4699756A1), and dysprosium titanate (Dy)₂O₃-TiO₂) (V.D.Risovany, E.E.Varlashova, D.N.Suslov, Dysprosiumtantalate sannabsorbmaterial for controls, journal of nuclear materials281(2000)84-89.) pellets, four absorber materials were located inside the control rod cladding tube.

B₄The C pellet is commercially available in VVER-1000 and EPR stack types, has high neutron absorption value, but B₄The absorption value of the C pellets is rapidly reduced along with the burnup of the fuel assembly, and a large amount of He gas is released after neutron reaction to cause large radiation swelling, so that the cladding tube is easy to bulge and damage, the service life is short, and the full-size large-scale application in the control rod is difficult.

The Hf rod has good corrosion resistance, processability, mechanical property and stable in-reactor irradiation property, the absorption sections of 6 isotopes of the Hf rod are higher, transmutation products Ta and W also have higher neutron absorption sections and longer half-life period, so that the Hf rod becomes the earliest nuclear reactorOne of the control rod absorbers. The Ag-In-Cd alloy rod is the most common commercial control rod absorber material at present, has initial reactivity value and consumption rate similar to that of a Hf rod, and has the main problems that the absorption value of the Hf rod and the Ag-In-Cd alloy rod is not ideal, the Hf rod and the Ag-In-Cd alloy rod are applied to a reactor with higher power, and the design flexibility is very low or even the shutdown depth requirement cannot be met. Dy (Dy)₂TiO₅Pellets work in MIR and VVER-1000 because of their lower radiation swelling, higher neutron absorption capacity, and melting point (-1870 ℃). Dy (Dy)₂TiO₅The initial reactivity value of the pellets is also similar to that of the Ag-In-Cd alloy rods, so that the problem of insufficient initial reactivity values similar to those of the Ag-In-Cd alloy rods and Hf rods is faced when a higher-power reactor is faced.

In conclusion, it is of great significance to develop neutron absorber materials without B control rods, which have high initial reactivity values and little change with the burnup of fuel assemblies.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a high-value control rod neutron absorber material which is high in initial reactivity value and small in fuel consumption change along with a fuel assembly, and can realize control of reactor operation power and shutdown.

The neutron absorber material of the high-value control rod comprises at least one first component and at least one second component, wherein the first component has good neutron absorption capacity, and the second component and the first component can form a stable compound; the initial reactivity value of the neutron absorber material is not lower than that of the Ag-In-Cd alloy rod, and the reactivity value is not faster than that of the Ag-In-Cd alloy rod along with the burn-up change rate of the fuel assembly.

Preferably, the first component contains at least Dy element: pure or substantially pure Dy metal, Dy alloy, Dy-based compound, or a mixture of the two Dy-containing materials mentioned above; the second component at least contains Al element: pure or substantially pure Al metal, Al alloys, Al-based compounds, and mixtures of the foregoing.

Preferably, the first component Dy alloy does not contain halogen elements and elements that are liable to react with stainless steel to form intermetallic compounds, and the mass percentage of Dy element is not less than 90%.

Preferably, the second component Al alloy does not contain halogen elements and elements which are easy to react with stainless steel to generate intermetallic compounds, and the mass percent of Al elements is not less than 90%.

Preferably, besides Dy, the first component Dy-based compound may further include one or more of Gd, Tb, Tm, Sm, Eu, Cd, Ir, Lu, In, Nd, and the like. The mass percent of Dy element is between 80 and 95 percent.

Preferably, the second component Al-based compound can also contain one or more of Ga, Ti, Zr, Nb, Mo, Hf, Ta, W, Si, Ge, Sb, Te and the like besides Al, and the mass percent of Al element is between 45 and 60 percent.

The invention has the following beneficial effects;

1. the nuclear physical comprehensive performance is improved, and the initial reactivity value of the absorber material is higher than that of Ag-In-Cd alloy rods, Hf rods and Dy₂TiO₅Core block, with B₄And C is compared. While the reactivity value varies with the burnup of the component and the Ag-In-Cd alloy rod, Hf rod and Dy₂TiO₅Pellets were comparable, significantly slower than B₄C, the design flexibility is increased;

2. with an increased use temperature limit, the absorber material according to the invention has a stable orthorhombic perovskite structure, in comparison with B₄The C core block (649 ℃) and the Ag-In-Cd alloy rod (800 ℃) have higher use temperature limit values (the melting point is higher than 1500 ℃, and no phase change exists from room temperature to the melting process), and the safety of a reactor core is improved.

Drawings

FIG. 1 shows Ag-In-Cd alloy rods and Dy with the same specification₂O₃-Al₂O₃A variation curve of pellet reactivity value versus module burnup;

FIG. 2 shows Ag-In-Cd alloy rods and (Dy) with the same specification₂O₃-Sm₂O₃)-Al₂O₃A variation curve of pellet reactivity value versus module burnup;

FIG. 3 shows the same specification of Ag-In-Cd alloyGold rod and Dy₂O₃-(Al₂O₃-HfO₂) A variation curve of pellet reactivity value versus module burnup;

FIG. 4 shows the density B of 70% in the same specification₄C pellet and Dy₂O₃-Al₂O₃The variation curve of pellet reactivity value versus module burnup.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples.