CN113161021A - Hollow uranium nitride fuel element of fast neutron reactor - Google Patents
Hollow uranium nitride fuel element of fast neutron reactor Download PDFInfo
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- CN113161021A CN113161021A CN202110450301.4A CN202110450301A CN113161021A CN 113161021 A CN113161021 A CN 113161021A CN 202110450301 A CN202110450301 A CN 202110450301A CN 113161021 A CN113161021 A CN 113161021A
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/42—Selection of substances for use as reactor fuel
- G21C3/58—Solid reactor fuel Pellets made of fissile material
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/02—Fuel elements
- G21C3/04—Constructional details
- G21C3/06—Casings; Jackets
- G21C3/08—Casings; Jackets provided with external means to promote heat-transfer, e.g. fins, baffles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
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Abstract
The invention provides a hollow uranium nitride fuel element of a fast neutron reactor, and relates to the technical field of nuclear engineering. The method comprises the following steps: a cylindrical core block; and a cladding arranged outside the side wall of the pellet; the center of the core block is provided with a through hole; a gap is arranged between the core block and the cladding; helium is filled in the gap between the through hole and the through hole. The fuel element provided by the invention is suitable for hollow UN fuel of a fast reactor, improves the utilization rate of uranium, avoids fuel cracking caused by high operating temperature and FCMI (fuel economy index) caused by fuel swelling, increases the fuel consumption, prolongs the service time of the fuel, and improves the economy and safety of a nuclear reactor.
Description
Technical Field
The invention relates to the technical field of nuclear engineering, in particular to a hollow uranium nitride fuel element of a fast neutron reactor.
Background
Compared with the traditional oxide fuel, the Uranium Nitride (UN) fuel has the advantages in multiple aspects: has higher heavy metal density; the heat conductivity is better; a characteristic that the thermal conductivity increases with an increase in temperature; the proliferation ratio of the mixed oxide fuel (MOX) is increased by about 10 percent, and the like. Due to these advantages, UN fuel has been considered for sodium-cooled fast reactors, lead-cooled fast reactors and space reactors for a long time, and even can meet the requirement of realizing no refueling for decades in some special environments, and is one of the most favored fuels in the future.
At the same time, however, UN fuel still faces some problems to be solved, the most important of which is the high temperature cracking tendency and severe swelling. According to the research results of the literature, although the UN fuel has a high melting point, the UN fuel often begins to decompose at about 1970K, and according to the design and operation conditions of the fast reactor MOX fuel which is well developed at present, the central temperature of the fuel can exceed 2300K, so that the use of the UN fuel in the fast reactor is greatly limited. The serious swelling is another fatal problem of the UN fuel, researchers conduct irradiation swelling experiment research on the nitride fuel at 1573-1673K, the swelling of the UN fuel is close to twice that of the oxide fuel under the condition, the serious swelling problem further influences core-package mechanical interaction (FCMI), and even causes the problems of pellet cracking, cladding failure and the like. These problems are often also the direct cause of core failure, and these negative effects not only reduce the efficiency of reactor operation, but also increase the safety hazards of the reactor.
How to solve these problems is always the focus of research and development. The fuel cracking mainly occurs under the condition of high temperature, the fuel temperature can be reduced to the maximum extent by adopting the design of the inner-side and outer-side double-cladding annular fuel, but the space for accommodating fission products is also reduced, so that the swelling problem is more obvious, and the problem is more prominent particularly under the condition of high fuel consumption. If only the fission product is taken into account and the porosity is increased during the preparation of the pellets, but the thermal conductivity of the pellets is greatly influenced by the porosity, the thermal conductivity will be reduced by 20% at 1500K as calculated from the relationship given by Rogozki (B.D. Rogozkin, N.M. Stepennova, Atomic Energy 95(3) (2003) 624-. These are clearly not the best ways to solve the problem.
Matzke (Matzke, Hj. science of Advanced LMFBR Fuels; North-Holland: Amsterdam,1986) found that there were different fuel structures in the UN fuel at different temperature zones in the reactor, as shown in FIG. 1, zone I being a porous structure that appeared in the central region of the fuel core block, temperatures typically higher than 1673K, swelling of up to 4% at 1% increase in burnup; region II is a columnar-like structure that is generally difficult to observe in UN fuel; the region III can generate crystal grain growth, a large amount of bubbles are generated in the crystal boundary, the release amount of fission gas is high, and the region III is also a main region for swelling; compared with the pellet prepared in the preparation process, the pellet in the area IV has only slight change, has the characteristics of small release amount of fission gas and small swelling, and generally exists only under 1423K.
For this reason, it is of great importance for the fuel to develop a system in which the temperature is controlled below 1423K, while ensuring more containment of fission products.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a hollow uranium nitride fuel element for a fast neutron reactor, which is suitable for hollow UN fuel of the fast reactor, can improve the utilization rate of uranium, avoid fuel cracking caused by high operating temperature and FCMI (cyclic Fuel index) caused by fuel swelling, increase the fuel consumption of fuel, prolong the service time of the fuel, and improve the economy and safety of a nuclear reactor.
The invention aims to provide a hollow uranium nitride fuel element of a fast neutron reactor, which comprises a hollow uranium nitride fuel element body;
a cylindrical core block; and a cladding arranged outside the side wall of the pellet;
the center of the core block is provided with a through hole;
a gap is arranged between the core block and the cladding;
helium is filled in the gap between the through hole and the through hole.
Preferably, the radius of the through hole is greater than or equal to 1/3 of the outer radius of the core block.
More preferably, the outer radius of the core block is 7.2-8.0 mm.
Preferably, the size of the gap is less than or equal to 0.2 mm.
Preferably, the porosity of the core block is 15 to 25%.
Preferably, the pellets are UN fuel.
Preferably, the cladding thickness is 1mm
More preferably, the material of the cladding is high-silicon iron steel.
Compared with the prior art, the invention has the beneficial effects that:
the hollow uranium nitride fuel element of the fast neutron reactor is suitable for hollow UN fuel of the fast reactor, improves utilization rate of uranium, avoids fuel cracking caused by high operating temperature and FCMI (cyclic Fuel index) caused by fuel swelling, reduces pressure for treating nuclear waste, increases fuel consumption, prolongs service time of fuel, can reduce cost of nuclear power, and improves economy and safety of the nuclear reactor.
The invention reduces the operating temperature of the fuel pellet by the hollow design of the pellet and the outward movement of the heat source, thereby effectively avoiding the defect of high-temperature cracking of UN fuel;
the invention contains fission products by reducing temperature, reducing swelling caused by fission gas, increasing fuel porosity and mesoporous design, thereby effectively reducing FCMI and improving reactor safety.
Drawings
FIG. 1 is a schematic diagram of a nitride fuel structure at different temperatures.
Fig. 2 is a schematic diagram of a structure of a hollow uranium nitride fuel element in a fast neutron reactor provided by an embodiment.
Fig. 3 is a schematic cross-sectional structure diagram of a hollow uranium nitride fuel element in a fast neutron reactor according to an embodiment.
Fig. 4 is a graph of the thermal conductivity of the fuel elements provided in examples 1 and 2.
Fig. 5 is a fuel temperature profile of the fuel elements provided in examples 1 and 2.
Detailed Description
In order to make the technical solutions of the present invention better understood and implemented by those skilled in the art, the present invention is further described with reference to the following specific examples, which are not intended to limit the present invention.
The following embodiments adopt a structural schematic diagram of a hollow uranium nitride fuel element of a fast neutron reactor, which is shown in fig. 2-3 and includes;
a cylindrical core block 1; and a cladding 3 arranged outside the side wall of the pellet 1;
the center of the core block 1 is provided with a through hole 2;
a gap 4 is arranged between the pellet 1 and the cladding 3;
helium is filled in the through hole 2 and the gap 4.
The invention takes the design of the lead-based fast reactor hollow UN fuel as an example, and the parameter values of the hollow UN fuel element during design are shown in the table 1.
TABLE 1 lead-based fast reactor hollow UN fuel design parameters
Example 1
A hollow uranium nitride fuel element of a fast neutron reactor is shown in figures 2-3 and comprises a cylindrical pellet 1; and a cladding 3 arranged outside the side wall of the pellet 1;
the center of the core block 1 is provided with a through hole 2;
a gap 4 is arranged between the pellet 1 and the cladding 3;
helium is filled in the through hole 2 and the gap 4.
The outer radius of the core block is 7.8mm, and the radius of the through hole is 2.6mm
The pellet is UN fuel, and the porosity is 15%;
the material of the cladding is high-silicon iron horse steel, and the thickness of the cladding is 1.0 mm;
the gap size was 0.04 mm.
Example 2
A hollow uranium nitride fuel element of a fast neutron reactor is shown in figures 2-3 and comprises a cylindrical pellet 1; and a cladding 3 arranged outside the side wall of the pellet 1;
the center of the core block 1 is provided with a through hole 2;
a gap 4 is arranged between the pellet 1 and the cladding 3;
helium is filled in the through hole 2 and the gap 4.
The outer radius of the core block is 7.8mm, and the radius of the through hole is 2.6mm
The pellet is UN fuel, and the porosity is 25%;
the material of the cladding is high-silicon iron horse steel, and the thickness of the cladding is 1.0 mm;
the gap size was 0.04 mm.
Example 3
The same as in example 1, except that,
the outer radius of the core block is 8.0 mm; the radius of the through hole is 4 mm;
the gap size was 0.02 mm.
Example 4
The same as in example 1, except that,
the outer radius of the core block is 7.2 mm; the radius of the through hole is 2.4 mm;
the gap size was 0.1 mm.
In order to illustrate various performances of the hollow uranium nitride fuel element in the fast neutron reactor provided by the invention, the fuel elements provided in the embodiments 1 and 2 are tested, and the tests are shown in fig. 4 to 5.
Fig. 4 is a graph of the thermal conductivity of the fuel elements provided in examples 1 and 2.
Fig. 5 is a fuel temperature profile of the fuel elements provided in examples 1 and 2.
As can be seen from fig. 4 and 5, the 25% porosity UN fuel has a significant reduction in thermal conductivity compared to 15%, but has a maximum effect on the temperature distribution of the final pellet of less than 30K, which allows us to accommodate fission products by a reasonable increase in porosity. The mesoporous structure design can also increase the space for accommodating fission products from another aspect, so as to solve the problem of UN fuel swelling, reduce FCMI and improve reactor safety.
From the aspect of structural design, the hollow fuel design can ensure that the fuel still safely operates under the condition of 20 percent of fuel consumption, basically can meet the requirement of no refueling for 20 years, and greatly improves the economy of the nuclear reactor. Meanwhile, the operation temperature of the reactor is greatly reduced, the FCMI is reduced, and the safety of the reactor is improved.
The invention can control the highest value of the pellet temperature of the fuel design of the fast neutron reactor loaded with the high-burnup UN fuel from the root, reduce fuel swelling and FCMI caused by the fuel swelling, obviously improve the burnup of the fuel and further expand the advantages of the high-burnup UN fuel in the fast reactor application.
In conclusion, the invention increases the effect of heat conduction by moving the heat source outwards through the design of the hollow fuel and reducing the core-package gap, thereby leading the temperature of the pellet to be in the range of lower than 1423K. Under the effect, the porosity of the fuel has a remarkable influence on the thermal conductivity, but has a small influence on the temperature distribution, so that the space for accommodating fission products can be increased by increasing the porosity; in addition, when the fuel swells to a certain degree, the pellets can move inwards due to the mesoporous structure, so that overlarge core-package stress caused by swelling is relieved, and the safety of the reactor core is improved. Therefore, the problem of the UN fuel in the fast reactor can be well solved through the design of the hollow fuel.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
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 also intended to include such modifications and variations.
Claims (8)
1. A hollow uranium nitride fuel element of a fast neutron reactor is characterized by comprising;
a cylindrical core block; and a cladding arranged outside the side wall of the pellet;
the center of the core block is provided with a through hole;
a gap is arranged between the core block and the cladding;
helium is filled in the gap between the through hole and the through hole.
2. The hollow uranium nitride fuel element for a fast neutron reactor according to claim 1, wherein the radius of the through hole is 1/3-1/2 of the outer radius of the pellet.
3. The fast neutron reactor hollow uranium nitride fuel element of claim 2, wherein the pellet outer radius is 7.2-8.0 mm.
4. The hollow uranium nitride fuel element for a fast neutron reactor according to claim 1, wherein the gap size is 0.02-0.1 mm.
5. The fast neutron reactor hollow uranium nitride fuel element of claim 1, wherein the pellet porosity is 15-25%.
6. The fast neutron reactor hollow uranium nitride fuel element of claim 1, wherein the pellets are UN fuel.
7. The fast neutron reactor hollow uranium nitride fuel element of claim 1, wherein the cladding thickness is 1 mm.
8. The hollow uranium nitride fuel element for a fast neutron reactor according to claim 7, wherein the cladding is made of high-silicon iron steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110450301.4A CN113161021A (en) | 2021-04-25 | 2021-04-25 | Hollow uranium nitride fuel element of fast neutron reactor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110450301.4A CN113161021A (en) | 2021-04-25 | 2021-04-25 | Hollow uranium nitride fuel element of fast neutron reactor |
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| CN113161021A true CN113161021A (en) | 2021-07-23 |
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| CN202110450301.4A Pending CN113161021A (en) | 2021-04-25 | 2021-04-25 | Hollow uranium nitride fuel element of fast neutron reactor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113593729A (en) * | 2021-07-27 | 2021-11-02 | 浙江大学 | Fast neutron reactor high-burnup metal fuel element using graphite foam as heat-conducting medium |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000147174A (en) * | 1998-11-04 | 2000-05-26 | Hitachi Ltd | Nuclear fuel element for light water reactor |
| RU2242810C2 (en) * | 2002-10-24 | 2004-12-20 | Открытое акционерное общество "Машиностроительный завод" | Fuel assembly for water-moderated water-cooled reactor |
| CN103295652A (en) * | 2012-02-24 | 2013-09-11 | 上海核工程研究设计院 | Nuclear fuel rod with ceramic cladding and metallic pellet |
| CN105814641A (en) * | 2013-10-30 | 2016-07-27 | 索尔能源有限公司 | A fuel assembly for a nuclear reactor |
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2021
- 2021-04-25 CN CN202110450301.4A patent/CN113161021A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000147174A (en) * | 1998-11-04 | 2000-05-26 | Hitachi Ltd | Nuclear fuel element for light water reactor |
| RU2242810C2 (en) * | 2002-10-24 | 2004-12-20 | Открытое акционерное общество "Машиностроительный завод" | Fuel assembly for water-moderated water-cooled reactor |
| CN103295652A (en) * | 2012-02-24 | 2013-09-11 | 上海核工程研究设计院 | Nuclear fuel rod with ceramic cladding and metallic pellet |
| CN105814641A (en) * | 2013-10-30 | 2016-07-27 | 索尔能源有限公司 | A fuel assembly for a nuclear reactor |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113593729A (en) * | 2021-07-27 | 2021-11-02 | 浙江大学 | Fast neutron reactor high-burnup metal fuel element using graphite foam as heat-conducting medium |
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