CN115547517A - Gadolinium-containing spherical fuel element for high-temperature gas cooled reactor - Google Patents
Gadolinium-containing spherical fuel element for high-temperature gas cooled reactor Download PDFInfo
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- CN115547517A CN115547517A CN202211179970.3A CN202211179970A CN115547517A CN 115547517 A CN115547517 A CN 115547517A CN 202211179970 A CN202211179970 A CN 202211179970A CN 115547517 A CN115547517 A CN 115547517A
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C5/00—Moderator or core structure; Selection of materials for use as moderator
- G21C5/12—Moderator or core structure; Selection of materials for use as moderator characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C5/00—Moderator or core structure; Selection of materials for use as moderator
- G21C5/12—Moderator or core structure; Selection of materials for use as moderator characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator
- G21C5/126—Carbonic moderators
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C5/00—Moderator or core structure; Selection of materials for use as moderator
- G21C5/14—Moderator or core structure; Selection of materials for use as moderator characterised by shape
- G21C5/16—Shape of its constituent parts
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor, which sequentially comprises a fuel area and a fuel-free area from inside to outside; the fuel region comprises coated fuel particles, gd 2 O 3 Particles and a graphite matrix; the coated fuel particle and the Gd 2 O 3 The particles are dispersed in the graphite matrix; 70-90 parts of the coated fuel particles, and Gd 2 O 3 10-30 parts of particles (the coated fuel particles and the Gd 2 O 3 The sum of the number of particles being 100 parts). The gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor improves the performance of the spherical fuel element 235 The U enrichment degree can reduce the loading quantity of fuel elements, improve the fuel consumption depth and improve the economic value under the same reactor power level.
Description
Technical Field
The invention belongs to the technical field of design of fuel elements of a pebble bed type high-temperature gas cooled reactor, and particularly relates to a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor.
Background
The pebble bed high-temperature gas cooled reactor is a nuclear reactor using helium as a coolant and graphite as a neutron moderator, is one of the fourth generation advanced reactor types, and is characterized by inherent safety. The pebble-bed high temperature gas cooled reactor includes a core formed of spherical fuel elements stacked within a reactor pressure vessel. The spherical fuel element is composed of a fuel area and a fuel-free area. The fuel region is a sphere coated with fuel particles dispersed in a graphite matrix. The fuel-free zone is a spherical shell of graphite matrix material of the same thickness and thickness as the fuel zone surrounding the fuel zone. The fuel region and the fuel-free region are free of a physical interface. The coated fuel particles are of the all-ceramic triple isotropic coating (TRISO) type, centered on the fuel core. Four cladding layers are arranged on the surface of the fuel core. The first layer from inside to outside is low density pyrolytic carbon, the second layer is high density isotropic pyrolytic carbon, the third layer is silicon carbide, and the fourth layer is high density isotropic pyrolytic carbon.
At present, the fuel core in the fuel element of the pebble-bed high-temperature gas cooled reactor has low enrichment degree () 235 U generally not exceeding 10%) uranium dioxide (UO) 2 ) In order to realize flattening of reactor core power distribution and uniform unloading fuel consumption, a fuel circulation mode that spherical fuel elements pass through the reactor core for multiple times is adopted; if the spherical fuel elements pass through the core less frequently, the power peak is higher and is positioned at the top of the core active area, which is unfavorable for the pebble-bed high temperature gas cooled reactor, and therefore, further optimization of the fuel elements in the existing high temperature gas cooled reactor is needed.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the embodiment of the invention provides a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor.
The embodiment of the invention provides a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor, which sequentially comprises a fuel area and a fuel-free area from inside to outside;
the fuel region comprises coated fuel particles, gd 2 O 3 Particles and a graphite matrix;
the coated fuel particle and the Gd 2 O 3 The particles are dispersed in the graphite matrix;
with the coated fuel particles and the Gd 2 O 3 The sum of the number of the particles is 100 parts, the number of the coated fuel particles is 70-90 parts, and the Gd is 2 O 3 10-30 parts of particles.
The gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor contains Gd 2 O 3 Material with a large thermal neutron absorption cross-section (Gd thermal neutron micro absorption cross-section 39800 target en, 1 target en = 10) -24 cm 2 ) The reactivity of new fuel can be compensated when the pebble bed type high-temperature gas-cooled reactor is initially loaded, and the fuel is preferentially consumed along with the fuel consumption process, so that the fuel backup reactivity of the pebble bed type high-temperature gas-cooled reactor in the transition cycle and the equilibrium cycle is ensured, and the continuous operation of the pebble bed type high-temperature gas-cooled reactor is met; the resulting gadolinium-containing spherical fuel element is enhanced in spherical fuel elements 235 The U enrichment degree improves the economic value of the product.
In some embodiments of the present invention, the coated fuel particle is preferably 80 to 85 parts, and the Gd is 2 O 3 The particles are preferably 15 to 20 parts by weight of the coated fuel particles and Gd 2 O 3 The sum of the number of particles is 100 parts.
In some embodiments of the invention, the Gd 2 O 3 The size of the particles is consistent with the size of the coated fuel particles; or, the Gd 2 O 3 The size of the particles corresponds to the size of the fuel core of the coated fuel particles.
In some embodiments of the present invention, in each of the gadolinium-containing spherical fuel elements for a high temperature gas cooled reactor, the number of the coated fuel particles is 10000 to 15000.
In some embodiments of the invention, the fuel core of the coated fuel particle is a UO of 0.5mm diameter 2 And (3) granules.
In some embodiments of the invention, the coated fuel particles have a diameter of any of 0.8mm, 0.92mm, or 1.0 mm.
In some embodiments of the present invention, the shape of the coated fuel particle is a sphere, and the coated fuel particle comprises a concentric fuel core, a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer from inside to outside.
The invention also provides a preparation method of the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor, which comprises the following steps:
(1) Preparation of UO by sol-gel process 2 Core: firstly, dissolving U by nitric acid 3 O 8 Adding organic binder into raw material powder to obtain colloid, and dispersing the colloid into ammonia water to obtain gel particles; then aging, washing, drying and roasting are carried out to obtain UO 3 Particles; finally, the compact UO is obtained by reduction and sintering 2 Ceramic particles;
(2) Preparing coated fuel particles: depositing a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer outside the fuel core in sequence by adopting a chemical vapor deposition method;
(3) Preparation of Gd 2 O 3 And (3) particle: mixing GdCl 3 The solution is obtained by extraction, back extraction, zinc powder reduction, oxalic acid precipitation, separation and ignition;
(4) Preparation of gadolinium-containing spherical fuel elements: coating fuel particles with Gd 2 O 3 Mixing the particles, coating a layer of graphite powder on the surface of the mixture, and performing compression molding to obtain a fuel area core sphere; then a layer of graphite powder is pressed on the surface of the core ball of the fuel area to be used as a fuel-free area; and then carbonizing, turning and purifying at high temperature to obtain the spherical fuel element containing gadolinium.
In the preparation method of the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor in the embodiment of the invention, the fuel element is added with the burnable poison Gd 2 O 3 The Gd is a natural element with a larger thermal neutron absorption section, so that the fuel element has larger excess reactivity, the excess reactivity is gradually released along with the consumption of the burnable poison, the effects of delaying the power peak value and flattening the power distribution are achieved, and only a small amount of Gd is required to be added 2 O 3 The reactivity control requirements can be met.
In some embodiments of the present invention, in step (1), the organic binder is a kind conventional in the art, such as an ester compound or a polymer prepared by dissolving a metal alkoxide in an organic solvent such as methanol, ethanol, propanol or butanol, such as polyvinyl alcohol.
In some embodiments of the invention, in the step (1), the roasting temperature is 500-600 ℃ and the roasting time is 1.5-2 h; the sintering temperature is 1550-1650 ℃, and the sintering time is 16-32 h.
In some embodiments of the invention, in the step (2), the chemical vapor deposition is performed to loosen the pyrolytic carbon layer for 10-30 min at the temperature of 1100-1300 ℃; carrying out chemical vapor deposition on the inner compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃; carrying out chemical vapor deposition on the silicon carbide layer for 2-5 h at the temperature of 1450-1650 ℃; carrying out chemical vapor deposition on the outer compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃.
In some embodiments of the present invention, in the step (3), the burning temperature is 900 to 1000 ℃, and the burning time is 1.5 to 2 hours.
In some embodiments of the invention, in step (3), the weight loss on ignition is no more than 1.5%; and after firing, gd 2 O 3 The content of (B) is not less than 99.8% (weight percentage);
wherein, gd 2 O 3 The isotope content (atomic percent) of gadolinium in the gadolinium is as follows:
155 Gd，14.9±1.0％；
157 Gd，15.7±1.0％。
in some embodiments of the invention, in the step (4), the carbonization temperature is 750-850 ℃ and the carbonization time is 30-50 h; the temperature of the high-temperature purification is 1150-1250 ℃, and the time is 10-20 h.
The invention has the following advantages and beneficial effects:
(1) The gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor improves the content of the spherical fuel element 235 The U enrichment degree can reduce the loading quantity of fuel elements, improve the fuel consumption depth and improve the economic value under the same reactor power level.
(2) By adopting the gadolinium-containing spherical fuel element for the high-temperature gas-cooled reactor, the cycle times of the spherical fuel element in the ball-bed high-temperature gas-cooled reactor can be reduced, the operation times of a fuel loading and unloading system can be reduced, and the reliability can be improved.
Drawings
Fig. 1 is a schematic structural diagram of a gadolinium-containing spherical fuel element for a high temperature gas cooled reactor according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The embodiment of the invention provides a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor, which sequentially comprises a fuel area and a fuel-free area from inside to outside;
wherein the fuel region comprises coated fuel particles, gd 2 O 3 Particles and a graphite matrix;
coated fuel particles and Gd 2 O 3 The particles are dispersed in the graphite matrix;
to coat the fuel particles with Gd 2 O 3 The sum of the number of the particles is 100 parts, wherein the coating fuel particles are 70-90 parts, and Gd is 2 O 3 10-30 parts of particles.
Gd is contained in the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor in the embodiment of the invention 2 O 3 Material with a large thermal neutron absorption cross-section (Gd thermal neutron micro absorption cross-section 39800 target en, 1 target en = 10) -24 cm 2 ) The reactivity of new fuel can be compensated when the pebble bed type high-temperature gas-cooled reactor is initially loaded, and the fuel is preferentially consumed along with the fuel consumption process, so that the fuel backup reactivity of the pebble bed type high-temperature gas-cooled reactor in the transition cycle and the equilibrium cycle is ensured, and the continuous operation of the pebble bed type high-temperature gas-cooled reactor is met; the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor can be improved 235 The U enrichment degree achieves the purpose of improving the fuel consumption and improves the economy of the ball bed type high-temperature gas cooled reactor; and gadolinium also commonly adopts gadolinium as a neutron burnable poison in a commercial pressurized water reactor, and has abundant application experience.
In some embodiments of the invention, the coated fuel particle is preferably 80 to 85 parts, gd 2 O 3 The particles are preferably 15 to 20 parts to coat the fuel particles with Gd 2 O 3 The sum of the number of the particles is 100 parts.
In some embodiments of the invention, gd 2 O 3 The size of the particles is consistent with the size of the coated fuel particles; or, gd 2 O 3 The size of the particles corresponds to the size of the fuel core that encapsulates the fuel particles.
In some embodiments of the present invention, the number of the coated fuel particles in each of the gadolinium-containing spherical fuel elements for a high temperature gas cooled reactor is 10000 to 15000.
In some embodiments of the invention, the fuel core encasing the fuel particles is a UO of 0.5mm diameter 2 And (3) granules.
In some embodiments of the invention, the coated fuel particles have a diameter of any of 0.8mm, 0.92mm, or 1.0 mm.
In some embodiments of the present invention, the shape of the coated fuel particle is a sphere, and the coated fuel particle comprises a concentric fuel core, a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer from inside to outside.
The invention also provides a preparation method of the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor, which comprises the following steps:
(1) Preparation of UO by sol-gel process 2 Core: firstly, dissolving U by nitric acid 3 O 8 Adding organic binder into raw material powder to obtain colloid, and dispersing the colloid into ammonia water to obtain gel particles; then aging, washing, drying and roasting are carried out to obtain UO 3 Particles; finally, the compact UO is obtained by reduction and sintering 2 Ceramic particles;
(2) Preparing coated fuel particles: depositing a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer outside the fuel core in sequence by adopting a chemical vapor deposition method;
(3) Preparation of Gd 2 O 3 And (3) particle: mixing GdCl 3 The solution is obtained by extraction, back extraction, zinc powder reduction, oxalic acid precipitation, separation and ignition;
(4) Preparation of gadolinium-containing spherical fuel elements: coating fuel particles with Gd 2 O 3 Mixing the particles, coating a layer of graphite powder on the surface of the mixture, and performing compression molding to obtain a fuel area core sphere; then a layer of graphite powder is pressed on the surface of the core ball of the fuel area to be used as a fuel-free area; and then carbonizing, turning and purifying at high temperature to obtain the spherical fuel element containing gadolinium.
In the preparation method of the gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor in the embodiment of the invention, the fuel element is added with the burnable poison Gd 2 O 3 The Gd is a natural element with a larger thermal neutron absorption section, so that the fuel element has larger excess reactivity, the excess reactivity is gradually released along with the consumption of the burnable poison, the effects of delaying the power peak value and flattening the power distribution are achieved, and only a small amount of Gd is required to be added 2 O 3 The reactivity control requirements can be met.
In some embodiments of the present invention, in step (1), the organic binder is a kind conventional in the art, such as an ester compound or a polymer prepared by dissolving a metal alkoxide in an organic solvent such as methanol, ethanol, propanol or butanol, such as polyvinyl alcohol.
In some embodiments of the present invention, in the step (1), the temperature of the calcination is 500 to 600 ℃, for example, 500 ℃, 520 ℃, 550 ℃, 580 ℃, 600 ℃, etc.; the time is 1.5 to 2 hours, for example, 1.5 hours, 1.6 hours, 1.8 hours, 2 hours and the like;
the sintering temperature is 1550 to 1650 ℃, for example 1550 ℃, 1580 ℃, 1600 ℃, 1620 ℃, 1650 ℃ and the like; the time is 16 to 32 hours, and for example, 16 hours, 18 hours, 20 hours, 24 hours, 28 hours, 30 hours, 32 hours and the like can be used.
In some embodiments of the invention, in the step (2), the chemical vapor deposition is carried out at the temperature of 1100-1300 ℃ for 10-30 min to loosen the pyrolytic carbon layer; carrying out chemical vapor deposition on the inner compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃; carrying out chemical vapor deposition on the silicon carbide layer for 2-5 h at the temperature of 1450-1650 ℃; carrying out chemical vapor deposition on the outer compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃.
In some embodiments of the present invention, in step (3), the burning temperature is 900-1000 ℃, for example, 900 ℃, 920 ℃, 950 ℃, 980 ℃, 1000 ℃, etc.; the burning time is 1.5 to 2 hours, and may be, for example, 1.5 hours, 1.6 hours, 1.8 hours, 2 hours, or the like.
In some embodiments of the invention, in step (3), the weight loss on ignition does not exceed 1.5%; and after firing, gd 2 O 3 The content of (B) is not less than 99.8% (weight percentage);
wherein, gd 2 O 3 The isotope content (atomic percent) of gadolinium in the gadolinium is as follows:
155 Gd，14.9±1.0％；
157 Gd，15.7±1.0％。
and after firing, per gram Gd 2 O 3 The maximum content (mu g/g) of single elements in the composition is as follows:
B，5；
Cd，25；
Th，30；
Cl+F，100；
Eu+Sm+Tb+Y+Dy，1000；
C，500。
the content of any other impurity not listed above should not exceed 1000 μ g/g Gd 2 O 3 (ii) a The total impurity content including the above impurities should not exceed 2000 μ g/g Gd 2 O 3 。
In some embodiments of the present invention, in step (4), the temperature of carbonization is 750 to 850 ℃, for example, 750 ℃, 780 ℃, 800 ℃, 820 ℃, 835 ℃, 850 ℃ and the like; the time is 30 to 50 hours, and may be, for example, 30 hours, 35 hours, 40 hours, 42 hours, 45 hours, 48 hours, 50 hours, or the like.
In some embodiments of the present invention, in the step (4), the temperature of the high-temperature purification is 1150 to 1250 ℃, for example, 1150 ℃, 1180 ℃, 1200 ℃, 1220 ℃, 1250 ℃, etc.; the time is 10 to 20 hours, and may be, for example, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, or the like.
The technical scheme of the invention is further described in detail by combining specific examples, wherein the experimental methods without specific conditions noted in the examples are conventional methods and conventional conditions well known in the field.
Example 1
The embodiment provides a gadolinium-containing spherical fuel element for a high-temperature gas-cooled reactor, and a preparation method of the gadolinium-containing spherical fuel element comprises the following steps:
(1) Preparation of UO by sol-gel process 2 A core: firstly 10g U 3 O 8 Mixing the raw material powder with nitric acid with the molar concentration of 16mol/L, and dissolving U by using the nitric acid 3 O 8 Raw material powder; then 5g of polyvinyl alcohol is added and mixed to obtain colloid; dispersing the obtained colloid into 10ml of 25% ammonia water to obtain gel particles; then aging, washing, drying and roasting at 600 ℃ for 1.5h to obtain UO 3 Particles; finally, reducing and sintering for 24h at 1600 ℃ to obtain compact UO 2 Ceramic particles of the UO 2 The diameter of the core is 0.50mm;
(2) Preparing coated fuel particles: depositing a loose pyrolytic carbon layer for 15min at 1250 ℃ outside the fuel core by adopting a chemical vapor deposition method; depositing the inner compact pyrolytic carbon layer at 1350 deg.c for 30min; depositing a silicon carbide layer at 1600 ℃ for 3h; finally, depositing an outer compact pyrolytic carbon layer at 1350 ℃ for 30min to obtain coated fuel particles with the diameter of 0.92 mm;
(3) Preparation of Gd 2 O 3 And (3) particle: 100mL of 95wt% GdCl 3 After the solution is extracted and back-extracted, 10g of zinc powder is added for reduction reaction; then adding 20g of oxalic acid for precipitation reaction, separating to obtain a precipitate after the reaction is finished, and finally burning the precipitate at 900 ℃ for 2h to obtain Gd with the particle size of 0.92mm 2 O 3 Particles;
(4) Preparing a spherical fuel element: coating fuel particles with Gd 2 O 3 Mixing the particles, coating a layer of graphite powder on the surface of the mixture, and performing compression molding to obtain a fuel area core sphere; then a layer of graphite powder is pressed on the surface of the core ball of the fuel area to be used as a fuel-free area; carbonizing at 800 ℃ for 40h, turning, and purifying at 1200 ℃ for 15h to obtain a gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor; in the obtained gadolinium-containing spherical fuel element for high-temperature gas cooled reactor, 8400 coating fuel particles are used, and Gd is 2 O 3 3600 particles.
Example 2
The embodiment provides a gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor, and a preparation method of the gadolinium-containing spherical fuel element, wherein the preparation method comprises the following steps of:
(1) Preparation of UO by sol-gel process 2 A core: firstly 10g U 3 O 8 Mixing the raw material powder with nitric acid with the molar concentration of 16mol/L, and dissolving U by using the nitric acid 3 O 8 Raw material powder; then 5g of polyvinyl alcohol is added and mixed to obtain colloid; dispersing the obtained colloid into 10ml of 25% ammonia water to obtain gel particles; then aging, washing, drying and roasting at 500 ℃ for 2h to obtain UO 3 Particles; finally, reducing and sintering for 24 hours at 1600 ℃ to obtain compactUO 2 Ceramic particles of the UO 2 The diameter of the core is 0.5mm;
(2) Preparing coated fuel particles: depositing a loose pyrolytic carbon layer outside the fuel core at 1250 ℃ for 10min by adopting a chemical vapor deposition method; depositing the inner compact pyrolytic carbon layer at 1350 deg.c for 15min; depositing a silicon carbide layer at 1600 ℃ for 2h; finally, depositing an outer compact pyrolytic carbon layer for 15min at 1350 ℃ to obtain coated fuel particles with the diameter of 0.80 mm;
(3) Preparation of Gd 2 O 3 And (3) particle: 90mL of 95wt% GdCl 3 After the solution is extracted and back-extracted, 9g of zinc powder is added for reduction reaction; then adding 18g of oxalic acid for precipitation reaction, separating to obtain a precipitate after the reaction is finished, and finally burning the precipitate at 900 ℃ for 2h to obtain Gd with the particle size of 0.80mm 2 O 3 Particles;
(4) Preparation of gadolinium-containing spherical fuel elements: coating fuel particles with Gd 2 O 3 Mixing the particles, coating a layer of graphite powder on the surface of the mixture, and performing compression molding to obtain a fuel area core sphere; then pressing a layer of graphite powder on the surface of the core ball in the fuel area to serve as a fuel-free area; carbonizing at 800 ℃ for 40h, turning, and purifying at 1200 ℃ for 15h to obtain a gadolinium-containing spherical fuel element for the high-temperature gas cooled reactor; the obtained gadolinium-containing spherical fuel element for high-temperature gas cooled reactor contains 10500 coated fuel particles of Gd 2 O 3 4500 particles.
Example 3
The preparation process of the gadolinium-containing spherical fuel element for the high-temperature gas-cooled reactor in this example is similar to that of the gadolinium-containing spherical fuel element for the high-temperature gas-cooled reactor in example 1, and the difference is only that: in this example, in step (4), 10800 coating fuel particles and Gd are contained in the gadolinium-containing spherical fuel element for high temperature gas cooled reactor 2 O 3 1200 particles.
Example 4
The preparation process of the gadolinium-containing spherical fuel element for the high-temperature gas-cooled reactor in this example is similar to that of the gadolinium-containing spherical fuel element for the high-temperature gas-cooled reactor in example 2, and the difference is only that: in this example, in step (4)12000 coating fuel particles and Gd in the gadolinium-containing spherical fuel element for high temperature gas cooled reactor 2 O 3 3000 particles are prepared.
In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A gadolinium-containing spherical fuel element for a high-temperature gas cooled reactor is characterized by comprising a fuel area and a fuel-free area from inside to outside in sequence;
the fuel region comprises coated fuel particles, gd 2 O 3 Particles and a graphite matrix;
the coated fuel particle and the Gd 2 O 3 The particles are dispersed in the graphite matrix;
with the coated fuel particles and the Gd 2 O 3 The sum of the number of the particles is 100 parts, the number of the coated fuel particles is 70-90 parts, and the Gd is 2 O 3 10-30 parts of particles.
2. The gadolinium-containing spherical fuel element for the high temperature gas cooled reactor as claimed in claim 1, wherein the gadolinium-containing spherical fuel element is formed of a material having a high thermal conductivity80-85 parts of the coated fuel particles, and Gd 2 O 3 15-20 parts of particles.
3. The gadolinium-containing spherical fuel element for a high temperature gas cooled reactor according to claims 1 to 2,
the Gd 2 O 3 The size of the particles is consistent with the size of the coated fuel particles;
or, the Gd 2 O 3 The size of the particles corresponds to the size of the fuel core of the coated fuel particles.
4. The gadolinium-containing spherical fuel element for high temperature gas cooled reactor as claimed in claim 1, wherein the number of the coated fuel particles in each gadolinium-containing spherical fuel element for high temperature gas cooled reactor is 10000-15000.
5. The gadolinium-containing spherical fuel element for a high temperature gas cooled reactor as claimed in claim 1, wherein the fuel core of the cladding fuel particle is UO with a diameter of 0.5mm 2 Particles; the coated fuel particles have a diameter of any one of 0.8mm, 0.92mm, or 1.0 mm.
6. The method for manufacturing a gadolinium-containing spherical fuel element for a high temperature gas cooled reactor as claimed in any one of claims 1 to 5, comprising the steps of:
(1) Preparation of UO by sol-gel process 2 A core: firstly, dissolving U by nitric acid 3 O 8 Adding organic binder into raw material powder to obtain colloid, and dispersing the colloid into ammonia water to obtain gel particles; then aging, washing, drying and roasting are carried out to obtain UO 3 Particles; finally, the compact UO is obtained by reduction and sintering 2 Ceramic particles;
(2) Preparing coated fuel particles: depositing a loose pyrolytic carbon layer, an inner compact pyrolytic carbon layer, a silicon carbide layer and an outer compact pyrolytic carbon layer outside the fuel core in sequence by adopting a chemical vapor deposition method;
(3) Preparation ofGd 2 O 3 And (3) particle: mixing GdCl 3 The solution is obtained by extraction, back extraction, zinc powder reduction, oxalic acid precipitation, separation and ignition;
(4) Preparation of gadolinium-containing spherical fuel elements: coating fuel particles with Gd 2 O 3 Mixing the particles, coating a layer of graphite powder on the surface of the mixture, and performing compression molding to obtain a fuel area core sphere; then a layer of graphite powder is pressed on the surface of the core ball of the fuel area to be used as a fuel-free area; and then carbonizing, turning and purifying at high temperature to obtain the spherical fuel element containing gadolinium.
7. The method according to claim 6, wherein in the step (1), the roasting temperature is 500-600 ℃ and the roasting time is 1.5-2 h; the sintering temperature is 1550-1650 ℃, and the sintering time is 16-32 h.
8. The method according to claim 6, wherein in the step (2), the loose pyrolytic carbon layer is formed by chemical vapor deposition at 1100-1300 ℃ for 10-30 min; carrying out chemical vapor deposition on the inner compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃; carrying out chemical vapor deposition on the silicon carbide layer for 2-5 h at the temperature of 1450-1650 ℃; carrying out chemical vapor deposition on the outer compact pyrolytic carbon layer for 15-45 min at the temperature of 1250-1500 ℃.
9. The method according to claim 6, wherein in the step (3), the burning temperature is 900-1000 ℃ and the burning time is 1.5-2 h.
10. The preparation method of the spherical gadolinium-containing fuel element for the high temperature gas cooled reactor according to claim 6, wherein in the step (4), the carbonization temperature is 750-850 ℃ and the carbonization time is 30-50 h; the high-temperature purification temperature is 1150-1250 ℃ and the time is 10-20 h.
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