GB2055671A - Transport and storage of irradiated nuclear fuel elements - Google Patents
Transport and storage of irradiated nuclear fuel elements Download PDFInfo
- Publication number
- GB2055671A GB2055671A GB8020679A GB8020679A GB2055671A GB 2055671 A GB2055671 A GB 2055671A GB 8020679 A GB8020679 A GB 8020679A GB 8020679 A GB8020679 A GB 8020679A GB 2055671 A GB2055671 A GB 2055671A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sleeves
- insert
- nuclear fuel
- sleeve
- neutron
- 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.)
- Granted
Links
- 239000003758 nuclear fuel Substances 0.000 title claims abstract description 21
- 239000000446 fuel Substances 0.000 claims abstract description 24
- 239000011358 absorbing material Substances 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims description 11
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 239000006096 absorbing agent Substances 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 abstract description 3
- 229910001220 stainless steel Inorganic materials 0.000 abstract description 3
- 229910052580 B4C Inorganic materials 0.000 abstract description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052782 aluminium Inorganic materials 0.000 abstract description 2
- 239000004411 aluminium Substances 0.000 abstract description 2
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 abstract description 2
- 239000006185 dispersion Substances 0.000 abstract description 2
- 239000011159 matrix material Substances 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000008188 pellet Substances 0.000 description 9
- 238000000429 assembly Methods 0.000 description 8
- 229910001093 Zr alloy Inorganic materials 0.000 description 3
- 230000000712 assembly Effects 0.000 description 3
- OOAWCECZEHPMBX-UHFFFAOYSA-N oxygen(2-);uranium(4+) Chemical compound [O-2].[O-2].[U+4] OOAWCECZEHPMBX-UHFFFAOYSA-N 0.000 description 3
- 238000012958 reprocessing Methods 0.000 description 3
- FCTBKIHDJGHPPO-UHFFFAOYSA-N uranium dioxide Inorganic materials O=[U]=O FCTBKIHDJGHPPO-UHFFFAOYSA-N 0.000 description 3
- 230000009257 reactivity Effects 0.000 description 2
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 230000004992 fission Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000013529 heat transfer fluid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 238000011076 safety test Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- OORLZFUTLGXMEF-UHFFFAOYSA-N sulfentrazone Chemical compound O=C1N(C(F)F)C(C)=NN1C1=CC(NS(C)(=O)=O)=C(Cl)C=C1Cl OORLZFUTLGXMEF-UHFFFAOYSA-N 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F5/00—Transportable or portable shielded containers
- G21F5/005—Containers for solid radioactive wastes, e.g. for ultimate disposal
- G21F5/008—Containers for fuel elements
- G21F5/012—Fuel element racks in the containers
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
An insert for a flask for transporting and storing irradiated nuclear fuel elements comprises an outer shell (1) housing a number of sleeves (4) for receiving the fuel elements, each sleeve being of square cross-section and manufactured from a neutron-absorbing material. The sleeves (4) are arranged with their centres lying on a circle (3), the centre of which coincides with the centre of the insert and with an edge of each sleeve forming at least a part of a side of a regular polygon having the same number of sides as the number of sleeves. A further sleeve (5) may be provided within the polygon. Each sleeve (4, 5) has outer and inner stainless steel sleeves with the space between them filled with a neutron-absorbing material, e.g. a dispersion of boron carbide in an aluminium matrix. The insert is designed such that the conditions which would permit a criticality excursion do not arise. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to the storage of nuclear fuel
This invention relates to the storage and transport of nuclear fuel and in particular to the storage of irradiated nuclear fuel after it has been removed from a nuclear reactor and before it is reprocessed to separate the reusable nuclear fuel materials such as uranium and plutonium from the products of nuclear fission.
Irradiated nuclear fuel is transported from the reactor to the reprocessing plant in specially constructed transport flasks which are so designed that the decay heat generated by the nuclear fuel material is dissipated during transport. As the transport flasks have to comply with stringent safety tests they are expensive to manufacture and so it is desirable that each one carries as much fuel as possible. To permit the movement of the flasks particularly by road and rail the flasks must not exceed a certain size and so their capacity is limited. The amount of irradiated nuclear fuel which can be accommodated is also limited by the need to dissipate the decay heat of the irradiated fuel.
An additional consideration in the design of transport flasks is the avoidance of critical excursions caused by the presence of the fissile material in the nuclear fuel material. The design must be such that a criticality incident cannot occur during normal use and during any possible accident which may occur during transportation of the flask.
Nuclear fuel material for pressurised water reactors (PWR) is contained in pellet form in tubular fuel pins'manufactured from a zirconium alloy such as that sold under the trade name
Zircaloy. Several pins are mounted in a square array in a fuel sub assembly which is inserted in the reactor core. A typical PWR fuel sub assembly is 8.5" square and contains an array of 14 by 14 fuel pins containing pellets of uranium dioxide enriched with 3.6% of the U235 isotope.
According to the present invention an insert for a transport flask for transporting nuclear fuel sub assemblies from a pressurised water reactor comprises a plurality of sleeves of square cross section manufactured from a neutron absorbing material into which the nuclear fuel elements may be placed, said sleeves being arranged in such a way that their centres lie on a circle the centre of which is at the centre of the insert and an edge of each sleeve forms at least part of a side of a regular polygon having the same number of sides as there are sleeves. Preferably five sleeves are provided. Conveniently a further sleeve may be located in the polygon to receive a further fuel element.
The sleeves may include a boron containing material to provide the neutron absorber and conveniently the boron-containing material may be located between inner and outer sleeve members.
The invention will be illustrated by the following description of an insert for a transport flask for transporting nuclear fuel sub assemblies. The description is given by way of example only and has reference to the accompanying drawings in which:
Figure 1 is a cross-sectional view of an insert for six nuclear fuel elements for a pressurised water reactor, and
Figure 2 is a cross-sectional view on a larger scale of a portion of the insert illustrated in Fig.
1.
The insert illustrated in Fig. 1 has an outer shell 1 containing five sleeves 2 of square crosssection arranged so that their centres lie on the chain dotted circle 3 which is concentric with the outer shell 1. The innermost edges 4 of the five sleeves lie along the edges of a regular pentagon. A further sleeve 5 is provided inside the pentagon. Each sleeve is intended to receive one fuel sub-assembly from a pressurised water reactor. The structure of each sleeve will now be described with reference to Fig. 2. The sleeve comprises outer and inner sleeve members 6, 7 of stainless steel which have a space 8 between them into which a neutron-absorbing material may be filled. Conveniently the neutron absorbing material is a boron containing material.A suitable material would be a dispersion of boron carbide in an aluminium matrix such as that produced by Brooks and Perkins Inc under the trade name "Boral".
In use the heat emitted by the fuel sub-assemblies is conducted to the shell 1 of the insert by a fluid such as water. To facilitate the circulation of the water the sleeves may have apertures 1 2 through the walls. The apertures would need to have cylindrical stainless steel walls linking the inner and outer sleeve member to prevent contact between the water and the neutron absorbing material.
In one particular embodiment the cavity inside the sleeve is 9 inches and the sleeve is 14' 4" in length so that the sleeve can receive a fuel assembly for a pressurised water reactor which has fuel pins 9 each of which comprises an outer tube 10 of zirconium alloy and a stack of pellets 11 of uranium dioxide. The fuel pins are arranged in a 1 4 X 14 square array and the sides of the sub-assembly are 8.5 inches long. The neutron absorbing material in the space 8 extends for the full length of the sleeves 2 and so the fuel sub-assembly is surrounded by neutron absorber when it is in the sleeve.
In use to transport irradiated fuel sub-assemblies the flask insert is placed inside a transport flask and the flask is lowered into the fuel storage pond of a nuclear reactor where fuel subassemblies are placed in to the sleeves. Water is placed in the flask and insert to provide a heat transfer fluid between the nuclear fuel sub-assemblies and the outer transport flask. The water also acts as a neutron absorbing moderator. The flask and insert are then sealed and the flask can be transported to a reprocessing plant. At the reprocessing plant the flask may be immersed in a waterfilled storage pond and the insert may be removed and stored under water in the pond until the fuel assemblies contained in the insert are to be reprocessed.
During the transportation and storage of nuclear fuelsit is essential that the conditions which would permit a criticality excursion do not arise. It is possible to calculate a value K effective for any particular system which gives an indication of the reactivity of the fuel. If the calculated K effective is less than unity the reactivity is taken to be sub-critical. In the design of transport flasks it is customary to work such that
Keff + 3CT0.95 where CT is the standard deviation. For the insert described above a calculation has been performed on an unirradiated nuclear fuel sub-assembly having pellets of uranium dioxide enriched to 3.6% of the U235 isotope. The pellets were contained in fuel pins arranged in a 14 x 14 square array with a pin centre to pin centre dimension of 0.607 inches.The pellets were contained in a central portion of each pin which is 1 50 inches long and which is centrally located within the sleeve. The calculations were repeated with different pellet diameters and the results are shown below.
pellet diameter inches Keff CT K+3o' 0.28 .7648 .0110 .7979 0.32 .7815 .0138 .8229 0.36 .8014 .0132 .8410 0.40 .7555 .0118 .7909
The calculations were repeated in the case of pellets of .36 inches diameter under conditions where it is assumed that 10% of the fissile mass is redistributed as a sludge which lies on the lower surfaces of the insert. When the insert is so positioned that the fuel sub-assemblies are horizontal the calculated value of Keffeetee is .7872 with a standard deviation of .0131 giving a value of Keff + 3(s of .8265. With the insert so positioned that the fuel sub-assemblies are vertical the calculated value is .8604 with a standard deviation of 0.1 22 giving a value of
Keff + 3a of .8970. These calculations show that even under the conditions in which some fuel pins are ruptured the fissile material will not form a critical mass. The calculated values show the large margin of safety which is exhibited by the insert described above.
Claims (7)
1. An insert for a nuclear fuel transport flask comprising a plurality of sleeves of square cross-section manufactured from a neutron absorbing material to receive nuclear fuel elements, the sleeves being arranged with their centres on a circle concentric with the centre of the insert and an edge of each sleeve forming at least part of a side of a regular polygon having the same number of sides as the number of sleeves, the sleeves having outer and inner wall members to define a space therebetween to receive a neutron-absorbing material.
2. An insert according to claim 1 including linked apertures spanning said wali members.
3. An insert according to claim 1 comprising five sleeves.
4. An insert according to claim 1 in which a further sleeve is located within the polygon to receive a further fuel element.
5. An insert according to claim 1 in which the neutron absorber within the wall members comprises a boron containing material.
6. An insert for a nuclear fuel transport flask substantially as herein described with reference to and as illustrated in the drawings.
7. A nuclear fuel transport flask containing an insert according to any preceding claim.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8020679A GB2055671B (en) | 1979-07-18 | 1980-06-24 | Transport and storage of irradiated nuclear fuel elements |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7925063 | 1979-07-18 | ||
| GB8020679A GB2055671B (en) | 1979-07-18 | 1980-06-24 | Transport and storage of irradiated nuclear fuel elements |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2055671A true GB2055671A (en) | 1981-03-11 |
| GB2055671B GB2055671B (en) | 1982-11-17 |
Family
ID=26272230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8020679A Expired GB2055671B (en) | 1979-07-18 | 1980-06-24 | Transport and storage of irradiated nuclear fuel elements |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2055671B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151068A (en) * | 1983-12-09 | 1985-07-10 | Kernforschungsanlage Juelich | Process for storing fuel elements |
| EP0171773A2 (en) * | 1984-08-17 | 1986-02-19 | Deutsche Gesellschaft für Wiederaufarbeitung von Kernbrennstoffen mbH | Storage container for isolated fuel rods of irradiated nuclear reactor fuel elements |
| EP0205060A2 (en) * | 1985-06-07 | 1986-12-17 | Gattys Technique S.A. | Radiation-protective container for the transport and disposal of radioactive materials, and method for its production |
| EP0281872A2 (en) * | 1987-03-11 | 1988-09-14 | Nukem GmbH | Reception arrangement for radioactive substances |
| FR2649528A1 (en) * | 1989-07-08 | 1991-01-11 | British Nuclear Fuels Plc | TRANSPORT CONTAINER FOR NUCLEAR FUEL ELEMENTS |
| US6580085B1 (en) * | 1998-02-10 | 2003-06-17 | Framatome | Transport container for nuclear fuel assemblies |
-
1980
- 1980-06-24 GB GB8020679A patent/GB2055671B/en not_active Expired
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151068A (en) * | 1983-12-09 | 1985-07-10 | Kernforschungsanlage Juelich | Process for storing fuel elements |
| EP0171773A2 (en) * | 1984-08-17 | 1986-02-19 | Deutsche Gesellschaft für Wiederaufarbeitung von Kernbrennstoffen mbH | Storage container for isolated fuel rods of irradiated nuclear reactor fuel elements |
| EP0171773A3 (en) * | 1984-08-17 | 1987-04-15 | Deutsche Gesellschaft Fur Wiederaufarbeitung Von Kernbrennstoffen Mbh | Storage container for isolated fuel rods of irradiated nuclear reactor fuel elements |
| EP0205060A2 (en) * | 1985-06-07 | 1986-12-17 | Gattys Technique S.A. | Radiation-protective container for the transport and disposal of radioactive materials, and method for its production |
| EP0205060A3 (en) * | 1985-06-07 | 1987-09-02 | Gattys Technique S.A. | Radiation-protective container for the transport and disposal of radioactive materials, and method for its production |
| EP0281872A2 (en) * | 1987-03-11 | 1988-09-14 | Nukem GmbH | Reception arrangement for radioactive substances |
| EP0281872A3 (en) * | 1987-03-11 | 1989-09-13 | Nukem GmbH | Reception arrangement for radioactive substances |
| FR2649528A1 (en) * | 1989-07-08 | 1991-01-11 | British Nuclear Fuels Plc | TRANSPORT CONTAINER FOR NUCLEAR FUEL ELEMENTS |
| US6580085B1 (en) * | 1998-02-10 | 2003-06-17 | Framatome | Transport container for nuclear fuel assemblies |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2055671B (en) | 1982-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20000623 |