GB2072928A - Fuel pin - Google Patents
Fuel pin Download PDFInfo
- Publication number
- GB2072928A GB2072928A GB8108274A GB8108274A GB2072928A GB 2072928 A GB2072928 A GB 2072928A GB 8108274 A GB8108274 A GB 8108274A GB 8108274 A GB8108274 A GB 8108274A GB 2072928 A GB2072928 A GB 2072928A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fuel
- nuclear
- rod
- tube
- fuel pin
- 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.)
- Withdrawn
Links
- 239000000446 fuel Substances 0.000 title claims description 41
- 239000008188 pellet Substances 0.000 claims abstract description 25
- 239000003758 nuclear fuel Substances 0.000 claims abstract description 18
- 239000002826 coolant Substances 0.000 claims abstract description 12
- 239000000919 ceramic Substances 0.000 claims abstract description 7
- 239000007769 metal material Substances 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 10
- 229910001093 Zr alloy Inorganic materials 0.000 claims description 7
- 230000004992 fission Effects 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical group [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000012634 fragment Substances 0.000 description 2
- 239000001307 helium Substances 0.000 description 2
- 229910052734 helium Inorganic materials 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 229910001256 stainless steel alloy Inorganic materials 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
- -1 water Chemical compound 0.000 description 1
Classifications
-
- 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
- G21C3/16—Details of the construction within the casing
- G21C3/18—Internal spacers or other non-active material within the casing, e.g. compensating for expansion of fuel rods or for compensating excess reactivity
-
- 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
Abstract
A nuclear reactor fuel pin in which a stack of annular ceramic nuclear fuel pellets (2) threaded onto a rod or tube (3) of non-fissile metallic material is contained in a sealed metallic can (1), with inert gas in the can interior at a pressure to equate with reactor coolant pressure during normal operation, and with a relatively small difference between the pellet external and internal diameter dimensions. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to nuclear reactor fuel
This invention relates to nuclear reactor fuel, and in particular to fuel pins, a multiplicity of which are included in the fuel assemblies which are charged into the core of a nuclear reactor.
A fuel pin for the fuel assemblies at present-day nuclear power stations with thermal nuclear reactors, for example AGRs and PWRs, and for designs of fast nuclear reactors, generally has a stack of solid or annular pellets of ceramic nuclear fuel enclosed in a sealed sheath or can of material, such as stainless steel or zirconium alloy, which is resistant to corrosion attack by coolant which is caused to flow over the can to remove heat generated by nuclear fission within the ceramic fuel material of the pellets. The kind of coolant varies with the type of nuclear reactor and may be a gas, such as carbon dioxide or helium, or a liquid such as water, or (particular for fast reactors) a liquid metal such as sodium.
There are problems associated with such fuel pins. One of these problems concerns fuel pellet/can interaction. During operation, each can is under compressive force due to coolant pressure and gradually creeps down onto the fuel.
At the same time, build-up of fission products causes the fuel to expand and come into firm contact with the can. Any power increase will cause the fuel to thermally expand and strain the can, and there is a limit to what the can may experience before failing. Another problem is that cracking or fracture of fuel pellets can be caused by thermal cycling of the ceramic fuel material during irradiation. Where the pellets are annular, fragments of fractured fuel can fall through the central hole to the bottom of the can where they can cause hot spots and be an embarrassment from the point of view of physical rearrangement of the fuel.
The first main problem can be dealt with in a manner which is known per se, to avoid hard contact between fuel and can by internally pressurising the fuel pin to approximately match the external coolant pressure during normal operation, thus allowing a margin either way for overpower and/or shutdown. However, it is made more difficult to effect by virtue of the fact that irradiation of the fuel produces gaseous fission products which add to the internal pressure which will tend to lift the can away from the fuel, creating a gas gap which will adversely affect heat transfer to the can and coolant and lead to higher fuel temperatures which will increase gas release and exacerbate the problem.
According to the invention, a nuclear reactor fuel pin comprises a stack of a multiplicity of annular ceramic nuclear fuel pellets threaded onto a rod or tube of non-fissile metallic material, the stack being sealed in a metallic can intended to be exposed to nuclear reactor coolant during operation, the difference between the external and internal diameters of each fuel pellet being relatively small, and the can interior being provided with a gas inert to the fuel, can and rod or tube to an amount such as substantially to equate with coolant pressure during normal operation in a nuclear reactor.
It will be appreciated that the central rod or tube will prevent fragments of fuel from falling down the hole otherwise provided by a stack of annular pellets. It will also be appreciated that the small difference between external and internal diameters of each fuel pellet will result in minimising the volume of fuel, and hence a reduction in the temperature of the fuel and a lowering of the rate of release of gaseous fission products. Thus, the uncertainties associated with pressure rising of the interior of each fuel pin are largely removed.
The length of the stack of fuel pellets is preferably less than the internal length of the can so as to provide a space for the collection of fission product gases on irradiation, and the pellets may be held against movement relative to the can by a coil spring mounted in the said space with its coils surrounding the rod or tube. The length of the latter, which may be unitary or may consist of several short lengths in end contact, approximates to the internal length of the can.
The relationship between the external and internal diameters of the annular pellets is preferably such that the internal diameter substantially lies within the range of one-half to seven-eighths of the external diameter. A typical example for the relationship is that the internal diameter is three-quarters of the external diameter.
The material of the rod or tube may be zirconium alloy such as an alloy of zirconium and aluminium, a stainless steel, a nickel alloy, or molybdenum.
One embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings, In which:
Figure 1 is a side view in medial section of a fuel pin for a nuclear reactor fuel assembly, and
Figure 2 is a plan view in section on line Il-Il of Figure 1. In the drawings, there is provided a fuel pin Ffor a fuel assembly for a nuclear reactor of the thermal type which comprises a metallic can or sheath 1 of stainless steel or zirconium alloy depending on the kind of coolant employed, zirconium alloys being particularly suitable to pressurised water or boiling water coolants, said sheath containing a stack of annular ceramic nuclear fuel (e.g. UO2) pellets 2 threaded onto a rod 2 or tube 3' (shown in chain dot lines) of fissile material, or non-fissile metallic materials such as a zirconium/aluminium alloy.The rod 3 or tube 3' may be unitary, as shown in Figure 1, or may consist of a number of shorter rod or tube lengths disposed end to end. The stack of fuel pellets 2 is shorter than the internal length of the sheath 1 by a finite amount providing a space 4 which can accommodate fission product gases upon irradiation and prevent undue pressurising of the sheath 1. A metal coil spring 5 interposed under compression between the uppermost pellet of the stack and the upper of 2 end caps 6 on the sheath 1 so as to prevent relative movement between pellets and sheath.The length of the rod 3 or tube 3' or the total length of their parts where nonunitary is substantially the same as the internal length of the sheath 1 so that the spring 5 can be threaded onto the upper end of the rod 3 or tube 3' or the upper of the parts thereof where nonunitary, which helps to prevent it from becoming displaced such as it could fail to exert a restraining force on the pellets 2.
The relationship between the external and internal diameters of the fuel pellets preferably lies within the range of one-half to seven-eights, and a typical example is that the internal diameter is substantially three-quarters of the external diameter.
Internal gas fillings of each fuel pin can be accomplished, for example, by providing an inlet to each pin and pressurising to a theoretically calculated pressure and then sealing the inlet, or can be formed by incorporating within the can a theoretically calculated amount of an agent intended to release, upon the fuel pin being brought up to its normal temperature of operation in a nuclear reactor, a quantity of inert gas such as helium calculated to bring the internal pressure of the fuel pin to a value which equates with the external coolant pressure. In the typical example of a fuel pin for a pressurised water reactor, the internal pressure would be 500 psi which would raise to 1 500 psi at the start of operation. Suitable material for the said agent is nickel or copper, which can absorb quantities of inert gas and hold them entrapped at ambient temperatures. Various initial gas pressures, from sub-atmospheric to around 500 psi can be employed, as required.
Other examples of non-fissile metallic materials for a central tube or rod are stainless steels, nickel alloys (which thus incorporate the nickel referred to in the preceding sentence for inert gas absorption purposes), and molybdenum.
From the above description, it can be seen that an improved fuel pin is provided.
Claims (8)
1. A nuclear reactor fuel pin comprising a stack of a multiplicity of annular ceramic nuclear fuel pellets threaded onto a rod or tube of non-fissile metallic material, the stack being sealed in a metallic can intended to be exposed to nuclear reactor coolant during operation, the difference between the external and internal diameters of each fuel pellet being relatively small, and the can interior being provided with a gas inert to the fuel, can and rod or tube to an amount such as substantially to equate with coolent pressure during normal operation in a nuclear reactor.
2. A nuclear reactor fuel pin as claimed in
Claim 1, in which the length of the stack of fuel pellets is less than the internal length of the can so as to provide a space for the collection of fission product gases on irradiation.
3. A nuclear reactor fuel pin as claimed in
Claim 2, in which the pellets are held against movement relative to the can by a coil spring mounted in said space with its coils surrounding the rod or tube.
4. A nuclear fuel pin as claimed in any one of the preceding claims, in which said rod or tube comprises several short lengths in end to end contact.
5. A nuclear fuel pin as claimed in any one of the preceding claims, in which the relationship between the external and internal diameters of the annular pellets is such that the internal diameter substantially lies within the range of one-half to seven-eighths of the external diameter.
6. A nuclear fuel pin as claimed in Claim 5, in which said relationship is that the internal diameter is three-quarters of the external diameter.
7. A nuclear fuel pin as claimed in any one of the preceding claims, in which the rod or tube is fabricated from the zirconium alloy.
8. A nuclear fuel pin substantially as hereinbefore described and as shown in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8108274A GB2072928A (en) | 1980-04-01 | 1981-03-17 | Fuel pin |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8010942 | 1980-04-01 | ||
| GB8108274A GB2072928A (en) | 1980-04-01 | 1981-03-17 | Fuel pin |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2072928A true GB2072928A (en) | 1981-10-07 |
Family
ID=26275056
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8108274A Withdrawn GB2072928A (en) | 1980-04-01 | 1981-03-17 | Fuel pin |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2072928A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2679369A1 (en) * | 1991-07-15 | 1993-01-22 | Doryokuro Kakunenryo | FUEL BAR FOR NUCLEAR REACTOR. |
| CN106782681A (en) * | 2016-12-23 | 2017-05-31 | 中广核研究院有限公司 | Three cold type fuel rod and fuel assembly |
-
1981
- 1981-03-17 GB GB8108274A patent/GB2072928A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2679369A1 (en) * | 1991-07-15 | 1993-01-22 | Doryokuro Kakunenryo | FUEL BAR FOR NUCLEAR REACTOR. |
| GB2258340A (en) * | 1991-07-15 | 1993-02-03 | Doryokuro Kakunenryo | Fuel rod for nuclear reactor |
| GB2258340B (en) * | 1991-07-15 | 1994-10-05 | Doryokuro Kakunenryo | Fuel rod for nuclear reactor |
| CN106782681A (en) * | 2016-12-23 | 2017-05-31 | 中广核研究院有限公司 | Three cold type fuel rod and fuel assembly |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |