Nuclear reactor matrix material, nuclear fuel and preparation method thereof

Abstract

The invention relates to the field of nuclear fuel pellets, in particular to a nuclear reactor matrix material, a nuclear fuel and a preparation method of the nuclear fuel. The base material is formed by 80-90 wt% of spherical W powder, 0-15 wt% of spherical Fe powder and 0-15 wt% of spherical Cu powder through a high-temperature hot pressing sintering forming process or an SPS sintering process. The nuclear fuel comprises the nuclear reactor base material provided by the technical scheme and a fuel phase dispersed in the nuclear reactor base material, and the volume of the fuel phase accounts for less than 40% of the total volume of the nuclear fuel. The nuclear fuel is prepared by mixing base material powder and fuel phase powder and then carrying out hot pressed sintering. The nuclear fuel prepared by the invention has the characteristics of high temperature resistance, high thermal conductivity, radiation damage resistance, excellent thermophysical properties and the like, and is suitable for preparing nuclear fuel of a small modular reactor.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel pellets, and more particularly to nuclear reactor matrix materials, nuclear fuel, and methods for their preparation. Background Technology

[0002] Compared to conventional energy sources, nuclear reactor power offers advantages such as high energy density, independence from the operating environment, and long service life. Miniaturized mobile nuclear energy systems are a crucial manifestation of a nation's asymmetric power, creating an urgent need for applications in underwater, vehicle-mounted, and airborne platforms.

[0003] In response to the requirements of reactor design and fuel engineering in metal dispersion reactor mobile power supplies, and taking into account the requirements of small modular reactor design for fuel elements as well as the nuclear performance, safety, and high-temperature operation performance of various materials, there is an urgent need for a suitable high-temperature resistant and high-thermal-conductivity nuclear reactor fuel. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide nuclear reactor matrix materials, nuclear fuel and their preparation methods, wherein the nuclear fuel made from the matrix material has the characteristics of high temperature resistance, high thermal conductivity, radiation damage resistance and excellent thermophysical properties, and is suitable for the preparation of nuclear fuel for small modular reactors.

[0005] This invention provides a nuclear reactor matrix material, which is formed by hot pressing and sintering 80% to 90 wt% spherical W powder, 0 to 15 wt% spherical Fe powder, and 0 to 15 wt% spherical Cu powder.

[0006] Furthermore, the particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5–50 μm.

[0007] Furthermore, the purity of the spherical W powder, spherical Fe powder, and spherical Cu powder is ≥99.9%.

[0008] This invention provides nuclear fuel, comprising the nuclear reactor matrix material described in the above-described technical solution and a fuel phase dispersed in the nuclear reactor matrix material.

[0009] The volume of the fuel phase accounts for less than 40% of the total volume of the nuclear fuel.

[0010] This invention provides a method for preparing a nuclear reactor matrix material, characterized by comprising the following steps:

[0011] Step S1: Mix 80%–90 wt% spherical W powder, 0–15 wt% spherical Fe powder, and 0–15 wt% spherical Cu powder to obtain a uniformly dispersed powder raw material;

[0012] Step S2: Prepare nuclear reactor matrix material by using high-temperature hot pressing sintering process or SPS sintering process for the powder material.

[0013] Furthermore, the particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5–50 μm.

[0014] Furthermore, the pressure of the hot pressing is 10-500 MPa, the hot pressing sintering temperature is 1000-1350℃, and the holding time is controlled between 4-180 min;

[0015] The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min, preferably 4–15 min.

[0016] This invention provides a method for preparing nuclear fuel, comprising the following steps:

[0017] Step S1: Mix the nuclear reactor matrix material powder with the fuel phase powder to obtain a uniformly dispersed raw material; the volume of the fuel phase powder accounts for less than 40% of the total volume of the raw material.

[0018] Step S2: The powder is processed into nuclear fuel using a high-temperature hot-pressing sintering process or an SPS hot-pressing sintering process.

[0019] Further, in step S1, the powder of the nuclear reactor matrix material includes: 0% to 90 wt% spherical W powder, 0 to 15 wt% spherical Fe powder, and 0 to 15 wt% spherical Cu powder, wherein the particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5 to 50 μm.

[0020] The mixing time is 1 to 2 hours.

[0021] Furthermore, the pressure of the hot pressing is 10-500 MPa, the hot pressing sintering temperature is 1000-1350℃, and the holding time is controlled between 4-180 min;

[0022] The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min, preferably 4–15 min.

[0023] Compared with the prior art, the nuclear reactor matrix material and nuclear fuel of the present invention have the characteristics of high temperature resistance and high thermal conductivity in the matrix material; the fuel phase is dispersed in the matrix material, and the fuel phase and the matrix material cooperate with each other, so that the nuclear fuel has the characteristics of high temperature resistance, high thermal conductivity, radiation damage resistance and excellent thermophysical properties, which can be used in small modular reactors, and its advanced nature has broad application prospects. Attached Figure Description

[0024] Figure 1 It is the microstructure of the W-Fe reactor matrix material after hot pressing and sintering;

[0025] Figure 2 The microstructure of SPS sintering for W-Fe-Cu reactor matrix material;

[0026] Figure 3 It is the microstructure of the W-Cu reactor matrix material after hot pressing and sintering. Detailed Implementation

[0027] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0028] An embodiment of the present invention discloses a nuclear reactor matrix material, which is formed by hot pressing and sintering 80% to 90 wt% spherical W powder, 0 to 15 wt% spherical Fe powder, and 0 to 15 wt% spherical Cu powder.

[0029] The particle sizes of the spherical W powder, spherical Fe powder, and spherical Cu powder are all 5–50 μm.

[0030] The purity of the spherical W powder, spherical Fe powder, and spherical Cu powder is ≥99.9%.

[0031] An embodiment of the present invention discloses a nuclear fuel comprising the nuclear reactor matrix material described in the above-described technical solution and a fuel phase dispersed in the nuclear reactor matrix material.

[0032] The mass of the fuel phase accounts for less than 40% of the total mass of the nuclear fuel.

[0033] An embodiment of the present invention discloses a method for preparing a nuclear reactor matrix material, comprising the following steps:

[0034] Step S1: Mix 80%–90 wt% spherical W powder, 0–15 wt% spherical Fe powder, and 0–15 wt% spherical Cu powder to obtain a uniformly dispersed powder raw material;

[0035] The particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5–50 μm.

[0036] The purity of the spherical W powder, spherical Fe powder, and spherical Cu powder is ≥99.9%;

[0037] The mixing time is preferably 1 to 2 hours;

[0038] Step S2: Prepare nuclear reactor matrix material by using high-temperature hot pressing sintering process or SPS sintering process for the powder material.

[0039] The pressure of the hot pressing is 10-500 MPa, preferably 250-350 MPa; the hot pressing sintering temperature is 1000-1350℃, preferably below 1050℃; and the holding time is controlled at 4-180 min, preferably 4-120 min.

[0040] The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min, preferably 4–15 min.

[0041] An embodiment of the present invention discloses a method for preparing nuclear fuel, comprising the following steps:

[0042] Step S1: Mix the nuclear reactor matrix material powder with the fuel phase powder to obtain a uniformly dispersed raw material; the volume of the fuel phase powder accounts for less than 40% of the total volume of the raw material.

[0043] To facilitate uniform dispersion of the fuel phase in the matrix material, various powders used to prepare the nuclear reactor matrix material are mixed with the fuel phase powder before sintering.

[0044] The nuclear reactor matrix material powder comprises: 0%–90 wt% spherical W powder, 0–15 wt% spherical Fe powder, and 0–15 wt% spherical Cu powder, wherein the particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5–50 μm; and the purity of the spherical W powder, spherical Fe powder, and spherical Cu powder is ≥99.9%.

[0045] The fuel phase can be uranium carbide, uranium nitride, or uranium dioxide, with uranium carbide being preferred. Uranium carbide outperforms UO2 in terms of uranium density and high-temperature thermal conductivity, and can improve the problems of high core temperature and high thermal stress in UO2 fuel reactors.

[0046] The mixing time is 1 to 2 hours;

[0047] Step S2: The powder is processed into nuclear fuel using a high-temperature hot-pressing sintering process or an SPS sintering process.

[0048] The pressure of the hot pressing is 10-500 MPa, preferably 250-350 MPa; the hot pressing sintering temperature is 1000-1350℃, preferably below 1050℃; and the holding time is controlled at 4-180 min, preferably 4-120 min.

[0049] The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min, preferably 4–15 min.

[0050] In this invention, W provides the material with superior high-temperature performance, while Fe and Cu provide it with superior thermal conductivity. Cu also acts as a metal lubricant during high-temperature pressing and molding, further improving heat conduction. Moreover, the nuclear fuel formed by the fuel phase dispersed in the tungsten material matrix described in this invention has excellent performance and is suitable for small modular reactors.

[0051] To further understand the present invention, the following detailed description of the nuclear reactor matrix material and its preparation method provided by the present invention is provided in conjunction with embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0052] Example 1

[0053] The total weight of spherical W powder used for pre-sintering the nuclear reactor matrix material is 90%, and the total weight of pure Fe powder is 10%, with a purity of 99.9% for both. The particle size of the spherical metal powder used for mixing is 5–50 μm, and the powder mixing time is 1 hour.

[0054] After mixing, the materials are hot-pressed and sintered. The hot-pressing pressure is 250 MPa, the hot-pressing temperature is 1300℃, and the holding time is 5 min. The resulting billet is hexagonal. The microstructure of the hot-pressed W-Fe reactor matrix material is as follows: Figure 1 As shown, Fe is uniformly distributed in the reactor matrix material.

[0055] Example 2

[0056] The total weight of spherical W powder used for pre-sintering the nuclear reactor matrix material is 90%, pure Fe powder is 9%, and pure Cu powder is 1%, with a purity of 99.9% for all powders. The particle size of the spherical metal powders used for mixing is 5–50 μm, and the powder mixing time is 1.5 h.

[0057] After mixing, the materials were sintered using the SPS (Special Purpose Sintering) process. The SPS sintering pressure was 60 MPa, the corresponding sintering temperature was 1050℃, and the holding time was 5 min. The billet produced by SPS sintering was cylindrical. The microstructure of the W-Fe-Cu reactor matrix material after hot pressing sintering is shown below. Figure 2 As shown, Fe and Cu are uniformly distributed in the reactor matrix material.

[0058] Example 3

[0059] Spherical W powder (90% by weight) and pure Cu powder (10% by weight), both with a purity of 99.9%, were mixed. The spherical metal powder used for mixing had a particle size of 5–50 μm, and the mixing time was 1 hour. After mixing, the mixture was hot-pressed and sintered at a pressure of 350 MPa, a temperature of 1000℃, and a holding time of 4 minutes. The resulting blank was hexagonal in shape. The microstructure of the W-Cu reactor matrix material after hot-pressing and sintering is shown below. Figure 3 As shown, Cu is uniformly distributed in the reactor matrix material.

[0060] Table 1. Properties of the matrix materials prepared in Examples 1-3

[0061]

[0062] Example 4

[0063] Take 60g of matrix powder and 30g of uranium carbide powder and mix for 1 hour;

[0064] The matrix powder comprises 54g of spherical tungsten powder and 6g of spherical iron powder;

[0065] After mixing, the materials are hot-pressed and sintered. The hot-pressing process has a pressure of 250 MPa, a hot-pressing sintering temperature of 1300℃, and a holding time of 5 min. The hot-pressed blank is hexagonal in shape, thus obtaining nuclear fuel.

[0066] Example 5

[0067] Take 70g of matrix powder and 30g of uranium carbide powder and mix for 1.5 hours;

[0068] The matrix powder comprises 63g of spherical tungsten powder, 6.3g of spherical iron powder, and 0.7g of spherical copper powder;

[0069] After mixing, the SPS sintering process is adopted; the pressure of the SPS sintering process is 60MPa, the corresponding sintering temperature is 1050℃, and the holding time is 5min; the blank produced by SPS sintering is cylindrical, and nuclear fuel is obtained.

[0070] Example 6

[0071] Take 80g of matrix powder and 20g of uranium carbide powder and mix for 1 hour;

[0072] The matrix powder comprises 72g of spherical tungsten powder and 8g of spherical copper powder;

[0073] After mixing, the materials are hot-pressed and sintered at a pressure of 350 MPa, a temperature of 1000℃, and a holding time of 4 min. The blank produced by hot-pressing and sintering is hexagonal in shape, thus obtaining nuclear fuel.

[0074] Supplement the performance parameters of the nuclear fuels prepared in Examples 4-6, including heat resistance, thermal conductivity, radiation damage resistance, or physical properties. These parameters should roughly reflect actual conditions; highly precise experimental data are not required.

[0075] It is mainly used to corroborate the beneficial effects.

[0076] Table 2. Performance of the nuclear fuels prepared in Examples 4-6

[0077]

[0078] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nuclear reactor matrix material, characterized in that, It is made by hot pressing and sintering 80% to 90 wt% spherical W powder, 0 to 15 wt% spherical Fe powder, and 0 to 15 wt% spherical Cu powder.

2. The nuclear reactor matrix material according to claim 1, characterized in that, The particle sizes of the spherical W powder, spherical Fe powder, and spherical Cu powder are all 5–50 μm.

3. The nuclear reactor matrix material according to claim 1, characterized in that, The purity of the spherical W powder, spherical Fe powder, and spherical Cu powder is ≥99.9%.

4. Nuclear fuel, characterized in that, Includes the nuclear reactor matrix material as described in any one of claims 1 to 3 and the fuel phase dispersed in the nuclear reactor matrix material. The volume of the fuel phase accounts for less than 40% of the total volume of the nuclear fuel.

5. A method for preparing nuclear reactor matrix materials, characterized in that, Includes the following steps: Step S1: Mix 80%–90 wt% spherical W powder, 0–15 wt% spherical Fe powder, and 0–15 wt% spherical Cu powder to obtain a uniformly dispersed powder raw material; Step S2: Prepare nuclear reactor matrix material by using high-temperature hot pressing sintering process or SPS sintering process for the powder material.

6. The method for preparing nuclear reactor matrix material according to claim 5, characterized in that, The particle sizes of the spherical W powder, spherical Fe powder, and spherical Cu powder are all 5–50 μm.

7. The method for preparing nuclear reactor matrix material according to claim 5, characterized in that, The hot pressing pressure is 10-500 MPa, the hot pressing sintering temperature is 1000-1350℃, and the holding time is controlled between 4-180 min. The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min.

8. A method for preparing nuclear fuel, characterized in that, Includes the following steps: Step S1: Mix the nuclear reactor matrix material powder with the fuel phase powder to obtain a uniformly dispersed raw material; the volume of the fuel phase powder accounts for less than 40% of the total volume of the raw material. Step S2: The powder is processed into nuclear fuel using a high-temperature hot-pressing sintering process or an SPS sintering process.

9. The method for preparing nuclear fuel according to claim 8, characterized in that, In step S1, the powder of the nuclear reactor matrix material includes: 0% to 90 wt% spherical W powder, 0% to 15 wt% spherical Fe powder, and 0% to 15 wt% spherical Cu powder, wherein the particle size of the spherical W powder, spherical Fe powder, and spherical Cu powder is 5 to 50 μm. The mixing time is 1 to 2 hours.

10. The method for preparing nuclear fuel according to claim 8, characterized in that, The hot pressing pressure is 10-500 MPa, the hot pressing sintering temperature is 1000-1350℃, and the holding time is controlled between 4-180 min. The pressure for SPS sintering is 20–80 MPa, the temperature is 1000–1350 °C, and the holding time is 4–30 min.

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