CN110606742B

CN110606742B - TiO for nuclear power2-Gd2O3Burnable poison ceramic material and preparation method thereof

Info

Publication number: CN110606742B
Application number: CN201911016644.9A
Authority: CN
Inventors: 王辉; 杜沛南; 孙永铎; 何琨; 潘小强; 解怀英; 邱绍宇
Original assignee: Nuclear Power Institute of China
Current assignee: Nuclear Power Institute of China
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2022-02-22
Anticipated expiration: 2039-10-24
Also published as: CN110606742A

Abstract

The invention discloses TiO for nuclear power₂‑Gd₂O₃The burnable poison ceramic material and the preparation method thereof solve the problem that TiO which can be effectively applied to nuclear power operation environment and effectively improve the safety and the economical efficiency of nuclear power is not found in the prior art₂‑Gd₂O₃Problems with burnable poison materials. The invention comprises (1) preparing Gd (NO)₃)₃And Ti (NO)₃)₄Preparing saturated (NH)₄)₂CO₃A solution; (2) will saturate (NH)₄)₂CO₃Adding the solution into the mixed solution for reaction to obtain a precipitate after the reaction; (3) cleaning the precipitate, and drying to obtain precursor powder; (4) placing the precursor powder at 500-550 ℃, preserving heat for 5-7 h, taking out and grinding to obtain powder; (5) and pressing and molding the powder, and sintering to obtain a finished product. The invention has the advantages of high density, high strength, high inherent safety and the like, and is suitable for advanced nuclear power water-cooled power stacks.

Description

TiO for nuclear power2-Gd2O3Burnable poison ceramic material and preparation method thereof

Technical Field

The invention relates to the field of composite ceramic materials, in particular to TiO for nuclear power₂-Gd₂O₃A burnable poison ceramic material and a preparation method thereof.

Background

TiO2/B is widely adopted in nuclear power reactors at home and abroad, particularly in reactor cores of pressurized water reactor nuclear power stations₄The C burnable poison material is used for controlling the initial reactivity of the reactor, realizing flattening the power distribution of the reactor core, improving the fuel consumption and prolonging the refueling period, thereby reducing the nuclear power operation cost and improving the operationSafety and reliability. However, with the increasing fuel consumption and core power of the advanced nuclear reactor of the new generation, Al₂O₃/B₄C burnable poison materials not only accelerate swelling but also reduce their chemical stability, thereby affecting the safety and economics of nuclear reactor operation.

In order to solve the problems, the existing pressurized water reactor nuclear fuel element is designed by adopting a zirconium alloy cladding. The method for preparing the composite ceramic material at home and abroad mainly comprises a ball milling method, a powder metallurgy method and the like. However, the composite ceramic material prepared by the method has the defects of difficult internal uniformity control, difficult densification, more internal pores and defects and the like, and generates a large amount of dust in the preparation process, thereby polluting the environment and damaging the body health of personnel.

And, due to TiO₂-Gd₂O₃When the porosity of the composite ceramic material is too large, water vapor can be adsorbed, so that the zirconium alloy cladding material is subjected to hydrogen embrittlement corrosion; TiO2₂Matrix and Gd₂O₃Degree of solid solution to TiO₂-Gd₂O₃The service performance of the composite ceramic material under high temperature conditions also has important influence. Thus, TiO prepared by the existing method₂-Gd₂O₃The burnable poison material can not further improve the safety and the economical efficiency of nuclear power operation; nor is there any document describing how to prepare TiO suitable for use in a nuclear fuel element of a hydropneumatic reactor₂-Gd₂O₃A method of burnable poison materials.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: TiO which can be effectively applied to nuclear power operation environment and can effectively improve the safety and the economical efficiency of nuclear power is not found in the prior art₂-Gd₂O₃The problem of burnable poison material, and aims to provide TiO for nuclear power₂-Gd₂O₃A burnable poison ceramic material and provides the TiO for nuclear power₂-Gd₂O₃A method for preparing a burnable poison ceramic material.

The invention is realized by the following technical scheme:

TiO for nuclear power₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized by comprising the following steps:

(1) preparation of Gd (NO)₃)₃And Ti (NO)₃)₄Preparing saturated (NH)₄)₂CO₃A solution;

(2) will saturate (NH)₄)₂CO₃Adding the solution into the mixed solution for reaction to obtain a precipitate after the reaction;

(3) cleaning the precipitate, and drying to obtain precursor powder;

(4) placing the precursor powder at 500-550 ℃, preserving heat for 5-7 h, taking out and grinding to obtain powder;

(5) and pressing and molding the powder, and sintering to obtain a finished product.

The finished product prepared by the method is TiO₂-Gd₂O₃Burnable poison material, finished product of the invention and Al₂O₃/B₄C has the following advantages compared with the prior art: one is a lower swelling rate; second is TiO₂Matrix and Gd₂O₃A readily formable solid solution minimizes the problem of homogeneity of burnable poison materials; III is TiO₂The substrate has excellent chemical stability to the cladding alloy and primary coolant.

And, TiO prepared by the coprecipitation method of the present invention₂-Gd₂O₃The burnable poison material can form a uniform displacement type solid solution, has the characteristics of high density, high strength and the like, and can overcome the defect that the zirconium alloy cladding material is subjected to hydrogen embrittlement corrosion due to the fact that water vapor is adsorbed when the porosity is too large. Also, the TiO prepared by the method of the present invention₂-Gd₂O₃The burnable poison material has the advantages of good uniformity, purity and crystal structure of chemical components of the obtained material, low sintering temperature, higher mechanical strength and the like. Through detection, the TiO prepared by the invention₂-Gd₂O₃The density of the burnable poison material is greater than 94.8% T.D.

Thus, the high density, good microstructure TiO of the present invention₂-Gd₂O₃The burnable poison material lays a foundation for the research of the burnable poison material with high inherent safety for nuclear power, provides technical support, and has higher academic value and engineering application value.

Further, the sintering in the step (5) is vacuum sintering, and the sintering conditions are as follows: vacuum degree of 10^-2～10^-3Pa, a sintering temperature of 1600-1650 ℃, a heat preservation time of 3-4H, a temperature rise rate of 30 ℃/min, and a sintering atmosphere of H₂。

Further, the drying conditions of the step (3) are as follows: drying for 5-6 h at 150-170 ℃.

Further, in the step (3), the precipitate is washed by absolute ethyl alcohol for 2-3 times.

Further, the reaction temperature of the step (2) is 50-55 ℃, and the reaction process is saturated (NH)₄)₂CO₃The adding speed of the solution is 2-4 ml/min, and the pH value of the reaction solution is kept at 6.5-8.5 in the reaction process.

Further, Gd (NO)₃)₃And Al (NO)₃)₃The preparation process of the mixed solution comprises the following steps:

gd with a purity of 99.9 percent₂O₃Drying the powder, adding deionized water, and dissolving with concentrated nitric acid under stirring to obtain Gd (NO)₃)₃A solution;

adding deionized water and absolute ethyl alcohol into nano titanium oxide powder, and adding concentrated nitric acid to dissolve the mixture under the condition of stirring to prepare a titanium sol solution;

mixing prepared Gd (NO)₃)₃The solution is dropped into the titanium sol solution and is continuously stirred for 20-25 min, and Gd (NO) can be formed₃)₃And Ti (NO)₃)₄The mixed solution of (1).

Further, the saturation (NH)₄)₂CO₃The preparation process of the solution is as follows: analytically pure solid ammonium carbonate is put into a container, deionized water is added and the mixture is continuously addedStirring to make saturated (NH)₄)₂CO₃And (3) solution.

Further, the step (2) is saturated with (NH)₄)₂CO₃After the solution addition was completed, anhydrous ethanol was added.

TiO for nuclear power₂-Gd₂O₃The burnable poison ceramic material is the TiO for nuclear power₂-Gd₂O₃The finished product is prepared by the preparation method of the burnable poison ceramic material.

Wherein, TiO₂-Gd₂O₃TiO in burnable poison ceramic material₂The mass percentage of (B) is less than 15%.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. TiO produced by the invention₂-Gd₂O₃The density of the burnable poison material is more than 95.5 percent T.D, the mechanical property (bending strength and fracture toughness) is excellent, the burnable poison material is suitable for an advanced nuclear power water-cooled power reactor, and the intrinsic safety is high;

2. the invention has no strict requirements on process equipment, is easy to realize, and has good sintering performance and good microstructure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limitations of the present invention.

Example 1

TiO2-Gd for nuclear power₂O₃A method of preparing a burnable poison ceramic material, comprising:

firstly, drying the nano titanium oxide powder for 3h at 500 ℃, weighing 100g of nano titanium oxide powder, putting the nano titanium oxide powder into a beaker, adding 100ml of deionized water and 30ml of absolute ethyl alcohol into the beaker, and adding 20ml of concentrated nitric acid into the beaker under the condition of rapid stirring to dissolve the mixture to obtain a stable titanium sol solution. Weighing 5.3g of dried gadolinium trioxide powder according to the mass ratio of gadolinium trioxide in the materialPlacing into a dissolving tank, adding 30ml deionized water, adding 7ml concentrated nitric acid under rapid stirring for dissolving for 28min, and filtering to obtain clear filtrate (Gd (NO)₃)₃And (3) solution. Mixing prepared Gd (NO) under the condition of rapid stirring₃)₃Slowly dropping the solution into the titanium sol solution, and continuously stirring for 25min to form uniform Gd (NO)₃)₃And Ti (NO)₃)₄The solution was mixed. 100g of analytically pure solid ammonium carbonate are weighed into a beaker, deionized water is added to the beaker and the mixture is stirred rapidly to form saturated (NH)₄)₂CO₃And (3) solution.

In the second step, Gd (NO) is added₃)₃And Ti (NO)₃)₄Adding the mixed solution into a precipitation tank, starting stirring, heating to the reaction temperature of 50 ℃, and then adding saturated (NH)₄)₂CO₃Dripping the solution into a precipitation tank at a speed of 2ml/min, adjusting the pH value of the mixed solution to keep the pH value at about 7, carrying out strong stirring while dripping to fully react, adding 30ml of absolute ethyl alcohol after the addition is finished, and precipitating the mixed solution after a period of time to completely react and lose fluidity. And then filtering the precipitate to obtain a filter cake, washing the filter cake for 2 times by using absolute ethyl alcohol, and drying at 150 ℃ for 6 hours to obtain precursor powder.

Thirdly, keeping the dried precursor powder in a box furnace at 500 ℃ for 7h, taking out after air cooling and grinding to obtain TiO₂-Gd₂O₃And (3) powder. Finally, the dried and calcined powder is pressed and molded (the molding pressure is 50MPa, the sample size is 50mm multiplied by 10mm) under the vacuum degree of 2.5 multiplied by 10^-3Pa, sintering temperature: 1600 ℃, the heat preservation time is 4H, the heating rate is 30 ℃/min, and the sintering atmosphere is H₂Vacuum sintering under the conditions of (1) to obtain compact TiO₂-Gd₂O₃A burnable poison ceramic material.

Example 2

The difference between this embodiment and embodiment 1 is that the specific process parameters of each step in this embodiment are different, and the specific settings are as follows:

in the second step, the pH of the mixed solution was maintained at about 8 during the reaction.

In the third step, the heat preservation temperature of the precursor powder is 520 ℃, and the heat preservation time is 6 hours; the vacuum sintering temperature is 1630 ℃, and the heat preservation time is 3.5 h.

Example 3

in the third step, the heat preservation temperature of the precursor powder is 550 ℃, and the heat preservation time is 5 hours; the vacuum sintering temperature is 1650 ℃, and the heat preservation time is 3 h.

Example 4

This example differs from example 1 in that Gd is present in this example₂O₃In different weight percentages, TiO in this example₂-Gd₂O₃TiO in burnable poison ceramic material₂Is 5% by weight.

Example 5

This example differs from example 1 in that Gd is present in this example₂O₃In different weight percentages, TiO in this example₂-Gd₂O₃TiO in burnable poison ceramic material₂Is 13% by weight.

Example 6

This example is a comparative example of examples 1 to 3, and the difference between this example and example 1 is that the process parameters of the steps in this example are different, and the specific settings are as follows:

in the second step, the pH of the mixed solution was maintained at about 6 during the reaction.

In the third step, the heat preservation temperature of the precursor powder is 570 ℃, and the heat preservation time is 4 hours; the vacuum sintering temperature is 1670 ℃, and the heat preservation time is 3 hours.

Example 7

in the second step, the pH of the mixed solution was maintained at about 9 during the reaction.

In the third step, the heat preservation temperature of the precursor powder is 480 ℃, and the heat preservation time is 8 hours; the vacuum sintering temperature is 1580 ℃, and the heat preservation time is 5 hours.

TiO prepared by the method described in examples 1-7₂-Gd₂O₃The burnable poison ceramic material is detected, the detected items comprise the detection of compactness, bending strength and fracture toughness, and the detection results are shown in Table 1

TABLE 1

	Compactness (relative density)	Bending strength	Fracture toughness
				Example 1	96.0％	300.8MPa	4.02MPa.m^1/2
Example 2	96.8％	301.5MPa	4.04MPa.m^1/2
				Example 3	95.9％	300.6MPa	4.02MPa.m^1/2
Example 4	95.7％	300.2MPa	4.03MPa.m^1/2
				Example 5	96.5％	301.1MPa	3.98MPa.m^1/2
Example 6	95.6％	299.1MPa	3.96MPa.m^1/2
				Example 7	95.5％	298.8MPa	3.97MPa.m^1/2

As is clear from the results shown in Table 1, TiO produced by the method of the present invention₂-Gd₂O₃The burnable poison ceramic material has higher density and excellent mechanical property, and can effectively lay a foundation for the research of the burnable poison material with high inherent safety for nuclear power and provide technical support.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. TiO for nuclear power₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized by comprising the following steps:

(3) cleaning the precipitate, and drying to obtain precursor powder;

(5) pressing and molding the powder, and sintering to obtain a finished product;

the reaction temperature of the step (2) is 50-55 ℃, and the reaction process is saturated (NH)₄)₂CO₃The adding speed of the solution is 2-4 ml/min, and the pH value of the reaction solution is kept at 6.5-8.5 in the reaction process.

2. TiO for nuclear power according to claim 1₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized in that the sintering in the step (5) is vacuum sintering, and the sintering conditions are as follows: vacuum degree of 10^-2～10^-3Pa, a sintering temperature of 1600-1650 ℃, a heat preservation time of 3-4H, a temperature rise rate of 30 ℃/min, and a sintering atmosphere of H₂。

3. TiO for nuclear power according to claim 1₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized in that the drying conditions in the step (3) are as follows: drying for 5-6 h at 150-170 ℃.

4. According to the claims3 the TiO for nuclear power₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized in that in the step (3), the precipitate is cleaned by absolute ethyl alcohol for 2-3 times.

5. TiO for nuclear power according to claim 1₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized in that Gd (NO)₃)₃And Al (NO)₃)₃The preparation process of the mixed solution comprises the following steps:

6. TiO for nuclear power according to claim 1₂-Gd₂O₃The method for preparing the burnable poison ceramic material is characterized in that the saturated (NH)₄)₂CO₃The preparation process of the solution is as follows:

analytically pure solid ammonium carbonate is placed in a container, deionized water is added and stirring is continued until saturation (NH)₄)₂CO₃And (3) solution.

7. TiO for nuclear power according to claim 1₂-Gd₂O₃The preparation method of the burnable poison ceramic material is characterized in that (NH) is saturated in the step (2)₄)₂CO₃After the solution addition was completed, anhydrous ethanol was added.

8. TiO for nuclear power₂-Gd₂O₃The burnable poison ceramic material is characterized by being a finished product prepared by the preparation method of any one of claims 1 to 7.

9. TiO for nuclear power according to claim 8₂-Gd₂O₃Burnable poison ceramic material, characterized in that the TiO is₂-Gd₂O₃TiO in burnable poison ceramic material₂The mass percentage of (B) is less than 15%.