CA1168769A - Fuel rod for a nuclear reactor - Google Patents
Fuel rod for a nuclear reactorInfo
- Publication number
- CA1168769A CA1168769A CA000385256A CA385256A CA1168769A CA 1168769 A CA1168769 A CA 1168769A CA 000385256 A CA000385256 A CA 000385256A CA 385256 A CA385256 A CA 385256A CA 1168769 A CA1168769 A CA 1168769A
- Authority
- CA
- Canada
- Prior art keywords
- ppm
- case
- exceed
- zirconium
- per cent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
Landscapes
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A fuel rod for a nuclear reactor comprises a cladding tube of zirconium-based alloy, on the internal surface of which there is arranged a layer of zirconium containing from 0.1 to 3 per cent by weight of molybdenum, and/or from 0.03 to 1 per cent by weight of carbon, and/or from 0.03 to 1 per cent by weight of phosphorus, and/or from 0.3 to 1 per cent by weight of silicon. The fuel rod contains a nuclear fuel, preferably uranium dioxide.
A fuel rod for a nuclear reactor comprises a cladding tube of zirconium-based alloy, on the internal surface of which there is arranged a layer of zirconium containing from 0.1 to 3 per cent by weight of molybdenum, and/or from 0.03 to 1 per cent by weight of carbon, and/or from 0.03 to 1 per cent by weight of phosphorus, and/or from 0.3 to 1 per cent by weight of silicon. The fuel rod contains a nuclear fuel, preferably uranium dioxide.
Description
~ 87~9 Fuel rod for a nuclear reactor Technical Field This invention relates to a fuel rod for a nuclear reactor, the fuel rod being of the kind comprising a cladding tube containing a nuclear fuel, ~or example pellets of 5 uranium dioxide.
Background Art The cladding tubes normal]y used in fuel rods for nuclear reactors comprise thin-walled tubes of zirconium-based alloys~ ;
for example the alloys known under the trade name "Zircaloy".
10 These alloys, which contain dissolved alloying materials such as tin, iron, nickel, chromium and oxygen, become irradiation-hardened under neutron irradiation. The irradiation hardening results in a brittling of the material and a considerably increased sensitivity to rod damage induced by stress corrosion.
15 To counteract this hardening, it is known to provide such cladding tubes internally with a layer of zirconium. Zircon-ium is well suited for this purpose, since it has good resist-ance to hardening when exposed to neutron irradiation, and since it is a relativel'y soft material. A zirconium layer c 20 on the internal surface of the cladding tube can therefore be plastically deformed and protect the cladding tube against stresses occurring in case of power changes during operation of the nuclear reactor in which the fuel rods are installed.
In the known cladding tubes with an internal zirconium 25 layer, the zirconium has had from 1,000 parts per million '(ppm) to 5,000 ppm. Of these impurities, from 200 to 1,200 ' ppm consist of oxygen. The amounts of the other impurities lie within the normal limits for the respective materials in commercial zirconi'um sponge of reactor quality, namely up to 75 ppm of aluminum, up to oD4 ppm of boron,'up to 0.4 ppm of cadmium, up to 270 ppm of carbon, up to 200 ppm of chromium, up to 20 ppm of cobalt, up to 50 ppm of copper, up to 100 ppm of hafnium, up to 25 ppm of hydrogen, up to 1,500 ppm of iron, .. . .
., ~
' ~ ~
l l ~ 9 up to 20 ppm of magnesium, up to 50 ppm of Manganese, up to 50 ppm of molybdenum, up to 70 ppm of nickel, up to lO0 ppm of niobium, up to 80 ppm of nitrogen, up to 120 ppm of silicon, up to 50 ppm of tin, up to 100 pp~ of tungsten, up to 50 ppm of titanium and up to 3.5 ppm of uranium.
The present invention aims to provide a fuel rod of the kind referred to, in which the cladding tube has a consider-ably improved resistance to stress corrosion compared with hitherto known fuel rods.
Disclosure of` the Invention According to the inven-tion, there is provided a nuclear reactor fuel rod comprising a cladding tube of a zirconium-based alloy, and a nuclear fuel within said cladding tube, wherein said cladding tube is lined internally with a layer of zirconium which contains at least one substance, selected from the group consisting of molybdenum, carbon, phosphorus and silicon, present in an amount, expressed as a percentage of the weight of the zirconium in said layer, which in the case of molybdenum is-from about 0.1 to about 3.0 per cent and in th~ case of carbon, phosphorus or silicon is from about 0u03 to about l.0 per cent.
C
In addition, the zirconium in said layer may contain -other impurities included in commercial zirconium sponge of ( reactor quality, for example at least one of the aforemention-ed impurities in the stated amounts.
A possible explanation of the improved resistance to stress corrosion of the cladding tube of a nuclear fuel rod according to the invention is as follows:
. . .
During manufacture of a cladding tube with an internal zirconium layer, which can be performed by extrusion, the materials are subJected to high temperatures. This results in a grain growth taking place in the zirconium, which is rapid in the case of the hitherto known zirconiu~ layer in - ::
" .' " ', ' , ' , 1 1 6 ~ 9 ` ` ', ~
which the alloying materials are dissolved. When one or more of the additives molybdenum, carbon, phosphorus and silicon is or are present in the above-stated amounts, a precipitation of stable compounds takes place, such as inter-5 metallic compounds, carbides, phosphides, silici~es, in the form of free particles in the zirconium matrix. This precipitation prevents the grain growth, so that a structure with smaller gr~ns is obtained in the zirconium than in the case of the hitherto known zirconium layer. The different, ( 10 fine-grained structure is responsible for the increasedresistance to stress corrosion. 5 The thickness of the zirconium layer in a fuel rod in accordance with the invention may be from about 0.005 to about 0.8 mm, and preferably from about 0.05 to about 0.1 15 mm.
The zirconium-based alloy cladding tube, on the internal surface of which the zirconium layer is provided, pre1er- -ably consists of a zirconium-tin alloy, for example the zirconium-based alloys known under the trade names '1Zircaloy 20 2" and "Zircaloy 4", whose contents of alloying materials are within the limits, by weight, of from lo ? to lo 7 per cent C of tin, from 0.07 to 0.2~ per cent of iron, from 0.05 to 0.15 per cent of chromium~ from 0.0 to o.o8 per cent of - nickel, and from 0.10 to 0.15 per cent of oxygen, the balance c 25 being zirconium and possibly existing impurities of ordinary kind. The nuclear fuel in the cladding tube preferably consists of uranium dioxide.
Brief Description of Drawing The invention will now be described, by way of example, 30 with reference to the accompanying drawing, the single Figure of which is a cross sectional view of a fuel rod according to the present invention for a light water nuclear reactor.
Desc~iption of Preferred_Embodime_ . Two par~s by weight of molybdenum are mixed with 98 parts .
. ' :
L 1687~9 by weight of the aforementioned commercial zirconium sponge of reactor quality and heated to form a melt. From this material there is ~ade a tube having a wall thiclmess o~ 1.25 m~
and an external diameter o~ 44 mm. The tube is arranged inside a tube of "Zircaloy 2" having a wall thickness of 10 mm and an internal diameter of 45 mm. The two tubes are welded together at the two end surfaces o~ the assembled tubesO The composite tube thus obtained is extruded at a temperature of about 600C. The extruded product is then - 10 cold-rolled in several stages with intermediate recrystalli-zation annealings, to produce the tubular end product shown in the Figure~ consisting of a layer 1 of '~Zircaloy 2"
having a thickness of 0.73 mm and an internal diameter of lOo 65 mm and of a layer 2 of zirconium with alloyed molybdenum having a thickness of 0.07 mm. The Figure also shows the nuclear fuel consisting o~ circular cylindrical pellets 3 cf uranium dioxide arranged end-to-end in the axial directlon of the cladding tube.
.
Instead of molybdenum in the above described example,there may be used 0.4 per cent by weight of carbon or o.8 per cent by weight of phosphorus or o.8 per cent by weight of silicon.
It is also possible to use two or more of the four components together in the stated amounts.
..~;
Background Art The cladding tubes normal]y used in fuel rods for nuclear reactors comprise thin-walled tubes of zirconium-based alloys~ ;
for example the alloys known under the trade name "Zircaloy".
10 These alloys, which contain dissolved alloying materials such as tin, iron, nickel, chromium and oxygen, become irradiation-hardened under neutron irradiation. The irradiation hardening results in a brittling of the material and a considerably increased sensitivity to rod damage induced by stress corrosion.
15 To counteract this hardening, it is known to provide such cladding tubes internally with a layer of zirconium. Zircon-ium is well suited for this purpose, since it has good resist-ance to hardening when exposed to neutron irradiation, and since it is a relativel'y soft material. A zirconium layer c 20 on the internal surface of the cladding tube can therefore be plastically deformed and protect the cladding tube against stresses occurring in case of power changes during operation of the nuclear reactor in which the fuel rods are installed.
In the known cladding tubes with an internal zirconium 25 layer, the zirconium has had from 1,000 parts per million '(ppm) to 5,000 ppm. Of these impurities, from 200 to 1,200 ' ppm consist of oxygen. The amounts of the other impurities lie within the normal limits for the respective materials in commercial zirconi'um sponge of reactor quality, namely up to 75 ppm of aluminum, up to oD4 ppm of boron,'up to 0.4 ppm of cadmium, up to 270 ppm of carbon, up to 200 ppm of chromium, up to 20 ppm of cobalt, up to 50 ppm of copper, up to 100 ppm of hafnium, up to 25 ppm of hydrogen, up to 1,500 ppm of iron, .. . .
., ~
' ~ ~
l l ~ 9 up to 20 ppm of magnesium, up to 50 ppm of Manganese, up to 50 ppm of molybdenum, up to 70 ppm of nickel, up to lO0 ppm of niobium, up to 80 ppm of nitrogen, up to 120 ppm of silicon, up to 50 ppm of tin, up to 100 pp~ of tungsten, up to 50 ppm of titanium and up to 3.5 ppm of uranium.
The present invention aims to provide a fuel rod of the kind referred to, in which the cladding tube has a consider-ably improved resistance to stress corrosion compared with hitherto known fuel rods.
Disclosure of` the Invention According to the inven-tion, there is provided a nuclear reactor fuel rod comprising a cladding tube of a zirconium-based alloy, and a nuclear fuel within said cladding tube, wherein said cladding tube is lined internally with a layer of zirconium which contains at least one substance, selected from the group consisting of molybdenum, carbon, phosphorus and silicon, present in an amount, expressed as a percentage of the weight of the zirconium in said layer, which in the case of molybdenum is-from about 0.1 to about 3.0 per cent and in th~ case of carbon, phosphorus or silicon is from about 0u03 to about l.0 per cent.
C
In addition, the zirconium in said layer may contain -other impurities included in commercial zirconium sponge of ( reactor quality, for example at least one of the aforemention-ed impurities in the stated amounts.
A possible explanation of the improved resistance to stress corrosion of the cladding tube of a nuclear fuel rod according to the invention is as follows:
. . .
During manufacture of a cladding tube with an internal zirconium layer, which can be performed by extrusion, the materials are subJected to high temperatures. This results in a grain growth taking place in the zirconium, which is rapid in the case of the hitherto known zirconiu~ layer in - ::
" .' " ', ' , ' , 1 1 6 ~ 9 ` ` ', ~
which the alloying materials are dissolved. When one or more of the additives molybdenum, carbon, phosphorus and silicon is or are present in the above-stated amounts, a precipitation of stable compounds takes place, such as inter-5 metallic compounds, carbides, phosphides, silici~es, in the form of free particles in the zirconium matrix. This precipitation prevents the grain growth, so that a structure with smaller gr~ns is obtained in the zirconium than in the case of the hitherto known zirconium layer. The different, ( 10 fine-grained structure is responsible for the increasedresistance to stress corrosion. 5 The thickness of the zirconium layer in a fuel rod in accordance with the invention may be from about 0.005 to about 0.8 mm, and preferably from about 0.05 to about 0.1 15 mm.
The zirconium-based alloy cladding tube, on the internal surface of which the zirconium layer is provided, pre1er- -ably consists of a zirconium-tin alloy, for example the zirconium-based alloys known under the trade names '1Zircaloy 20 2" and "Zircaloy 4", whose contents of alloying materials are within the limits, by weight, of from lo ? to lo 7 per cent C of tin, from 0.07 to 0.2~ per cent of iron, from 0.05 to 0.15 per cent of chromium~ from 0.0 to o.o8 per cent of - nickel, and from 0.10 to 0.15 per cent of oxygen, the balance c 25 being zirconium and possibly existing impurities of ordinary kind. The nuclear fuel in the cladding tube preferably consists of uranium dioxide.
Brief Description of Drawing The invention will now be described, by way of example, 30 with reference to the accompanying drawing, the single Figure of which is a cross sectional view of a fuel rod according to the present invention for a light water nuclear reactor.
Desc~iption of Preferred_Embodime_ . Two par~s by weight of molybdenum are mixed with 98 parts .
. ' :
L 1687~9 by weight of the aforementioned commercial zirconium sponge of reactor quality and heated to form a melt. From this material there is ~ade a tube having a wall thiclmess o~ 1.25 m~
and an external diameter o~ 44 mm. The tube is arranged inside a tube of "Zircaloy 2" having a wall thickness of 10 mm and an internal diameter of 45 mm. The two tubes are welded together at the two end surfaces o~ the assembled tubesO The composite tube thus obtained is extruded at a temperature of about 600C. The extruded product is then - 10 cold-rolled in several stages with intermediate recrystalli-zation annealings, to produce the tubular end product shown in the Figure~ consisting of a layer 1 of '~Zircaloy 2"
having a thickness of 0.73 mm and an internal diameter of lOo 65 mm and of a layer 2 of zirconium with alloyed molybdenum having a thickness of 0.07 mm. The Figure also shows the nuclear fuel consisting o~ circular cylindrical pellets 3 cf uranium dioxide arranged end-to-end in the axial directlon of the cladding tube.
.
Instead of molybdenum in the above described example,there may be used 0.4 per cent by weight of carbon or o.8 per cent by weight of phosphorus or o.8 per cent by weight of silicon.
It is also possible to use two or more of the four components together in the stated amounts.
..~;
Claims (6)
1. A nuclear reactor fuel rod comprising a cladding tube of a zirconium-based alloy, and a nuclear fuel within said cladding tube, wherein said cladding tube is lined internally with a layer of zirconium which contains at least one substance, selected from the group consisting of molybdenum, carbon, phosphorus and silicon, present in an amount, expressed as a percentage of the weight of the zirconium in said layer, which in the case of molybdenum is from about 0.1 to about 3.0 per cent and in the case of carbon, phosphorus or silicon is from about 0.03 to about 1.0 per cent.
2. A nuclear reactor fuel rod according to claim 1, wherein the zirconium of said layer contains, in addition, one or more substances selected from the group consisting of aluminum, boron, cadmium, chromium, cobalt, copper, hafnium, hydrogen, iron, magnesium, manganese, nickel, niobium, nitrogen, tin, tungsten, titanium and uranium, present in an amount, expressed in parts per million (ppm) by weight of the weight of zirconium in said layer, which in the case of aluminum does not exceed about 75 ppm, in the case of boron does not exceed about 0.4 ppm, in the case of cadmium does not exceed about 0.4 ppm, in the case of chromium does not exceed about 200 ppm, in the case of cobalt does not exceed about 20 ppm, in the case of copper does not exceed about 50 ppm, in the case of hafnium does not exceed about 100 ppm, in the case of hydrogen does not exceed about 25 ppm, in the case Or iron does not exceed about 1,500 ppm, in the case of magnesium does not exceed about 20 ppm, in the case of manganese does not exceed about 50 ppm, in the case of nickel does not exceed about 70 ppm, in the case of niobium does not exceed about 100 ppm, in the case of nitrogen does not exceed about 80 ppm, in the case of tin does not exceed about 50 ppm, in the case of tungsten does not exceed about 100 ppm, in the case of titanium does not exceed about 50 ppm, and in the case of uranium does not exceed about 3.5 ppm.
3. A nuclear reactor fuel rod according to claim 1 or 2, wherein the zirconium-based alloy of said cladding tube contains, by weight, from about 1.2 to about 1.7 per cent of tin, from about 0.07 to about 0.24 per cent of iron, from about 0.05 to about 0.15 per cent of chronium, from 0 to about 0.8 per cent of nickel, and from about 0.10 to about 0.15 per cent of oxygen, the balance being zirconium and conventional impurities.
4. A nuclear reactor fuel rod according to claim 1 or 2, wherein said nuclear fuel consists of uranium dioxide.
5. A nuclear reactor fuel rod according to claim 1, wherein said zirconium layer has a thickness of from about 0.005 to about 0.8 mm.
6. A nuclear reactor fuel rod according to claim 5, wherein said zirconium layer has a thickness of from about 0.05 to about 0.1 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000385256A CA1168769A (en) | 1981-09-04 | 1981-09-04 | Fuel rod for a nuclear reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000385256A CA1168769A (en) | 1981-09-04 | 1981-09-04 | Fuel rod for a nuclear reactor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168769A true CA1168769A (en) | 1984-06-05 |
Family
ID=4120879
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000385256A Expired CA1168769A (en) | 1981-09-04 | 1981-09-04 | Fuel rod for a nuclear reactor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1168769A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4751045A (en) * | 1985-10-22 | 1988-06-14 | Westinghouse Electric Corp. | PCI resistant light water reactor fuel cladding |
| US4933136A (en) * | 1985-03-08 | 1990-06-12 | Westinghouse Electric Corp. | Water reactor fuel cladding |
| US5373541A (en) * | 1992-01-17 | 1994-12-13 | Framatome | Nuclear fuel rod and method of manufacturing the cladding of such a rod |
-
1981
- 1981-09-04 CA CA000385256A patent/CA1168769A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4933136A (en) * | 1985-03-08 | 1990-06-12 | Westinghouse Electric Corp. | Water reactor fuel cladding |
| US4751045A (en) * | 1985-10-22 | 1988-06-14 | Westinghouse Electric Corp. | PCI resistant light water reactor fuel cladding |
| US5373541A (en) * | 1992-01-17 | 1994-12-13 | Framatome | Nuclear fuel rod and method of manufacturing the cladding of such a rod |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |