US3845178A - Manufacture of fuel for nuclear reactors utilizing a polymerisable resin - Google Patents
Manufacture of fuel for nuclear reactors utilizing a polymerisable resin Download PDFInfo
- Publication number
- US3845178A US3845178A US00194488A US19448871A US3845178A US 3845178 A US3845178 A US 3845178A US 00194488 A US00194488 A US 00194488A US 19448871 A US19448871 A US 19448871A US 3845178 A US3845178 A US 3845178A
- Authority
- US
- United States
- Prior art keywords
- die
- contents
- resin
- cavity
- fuel
- 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 - Lifetime
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C21/00—Apparatus or processes specially adapted to the manufacture of reactors or parts thereof
- G21C21/02—Manufacture of fuel elements or breeder elements contained in non-active casings
-
- 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
- G21C3/62—Ceramic fuel
-
- 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
Definitions
- This invention relates to the manufacture of fuel for nuclear reactors.
- fission product retaining fuel in the form of solid compacts, each compact comprising a certain number of nuclear fuel kernels bearing fission product-retentive coatings and held in a firm matrix of a suitable material.
- the percentage of the volume of compact occupied by coated fuel particles is termed the fuel volume loading and for high temperature thermal reactors a loading of, say, 35% is typical.
- the matrix material should be such as to give the compact a good dimensional stability during its lifetime in the reactor and should preserve its integrity during this period and during its charge into, and discharge from the reactor. In the case of a graphite matrix, for example, this means that the matrix must be nearly isotropic, of large crystallite size and of good chemical stability at high temperature in the presence of oxidising impurities.
- a mixture including fission product retaining fuel particles, a polymerisable resin and granular matrix material are pressed in a die cavity under substantially isothermal conditions at a temperature at which the resin melts but does not suffer a change in chemical structure and, together with the matrix material, exhibits a plasticity which allows compaction throughout the die cavity.
- Temperature conditions which are sufficiently uniform for performing the invention may be achieved by heating the die, die plungers and die contents in an oven at a slow rate, e.g. at rates of up to about 4 C. per minute. Faster rates may be permitted, however, depending upon the size of the die, and the resin used. To compensate for the adverse effect which a slow heating rate may have upon the economics of quantity production of compacts, a multiple die body is envisaged in which a large number of die cavities are heated simultaneously.
- a polymerisable resin which is chemically unchanged during the heating and pressing stage.
- a phenol-formaldehyde resin having a low ortho content, is suitable; the formaldehyde/phenol molecular ratio therein is preferably less than one but nevertheless close to unity.
- a hardener such as hexamine, could be added to the resin but care must be taken in this regard to avoid premature polymerisation of the resin binder, for example during the isothermal conditions of pressing to compact the die contents.
- Nuclear fuel kernels of uranium oxide of an average diameter 800 m and having a porosity of 20% were coated with multiple layers of fission product retentive material to a total coating thickness of 216 mg.
- the density of the coated particles was 4.2 g./cc. and their uranium content represented 60% of their total weight.
- a 1 kg. batch of these coated particles were then overcoated with 700 grams of graphite matrix forming powder.
- the matrix forming material was in fact a graphitised petroleum coke powder precoated with 12% by weight of solid phenol formaldehyde resin.
- the resin was specially selected so as to remain chemically unchanged at temperatures at which it exhibits low viscosity and high plasticity to the extent that the pressing pressure to consolidate the final compact can be exceeding low.
- the selected resin had a high molecular weight, a low free phenol content, i.e. less than 1%, and a formaldehyde/phenol molecular ratio of less than one but nevertheless close to unity. No hardener was added.
- a suitable phenol-formaldehyde resin has typically the following properties:
- the overcoating process itself was performed in accordance with the method described in U. K. Pat. No. 1,081,- 447, a batch of coated particles being rolled in a rotating drum into which the matrix forming material and methylated spirits were sprayed such that the coated particles acquired an overcoating of matrix forming material.
- the particle diameter was thus increased from an average of 1230 to 1750 Ill 1.. These were then dried over-night at 50 under 200 mm. pressure of flowing nitrogen.
- a three-part die block was prepared having 30 parallel cylindrical cavities in one part and upper and lower punches. Aliquots of 14.5 gram overcoated particles were weighed and with the upper punches removed but with the lower punches in position, the die cavities were each charged with this quantity of overcoated particles having the correct filler/fuel proportions for the desired volume loading of 39%. The die was then closed with the punches entering their respective die cavities and the whole block was placed in an oven. The block and contents were then heated slowly and uniformly to 150 C. during 30 minutes. It was then removed from the oven and placed between the thermally insulated platens of a hydraulic press.
- the press was operated so that all 30 upper and lower punches pressed the contents of their respective die cavities and applied a pressure of about 75 kg./cm. to the die contents under isothermal conditions.
- the shape of the die and the positions of the end stops were such that cylindrical compacts 11.92 mm. diameter and 50.4 mm. length were formed.
- the die was then locked and the block was further heated to 250 C. at which temperature the resin was cured.
- the die was removed from the oven and cooled in air. When the temperature had dropped to 100 C. the compacts were ejected from the die.
- the volume loading of the coated particles in the compacts was found to be 39% corresponding to a heavy metal content of 0.98 g./cc. of compact volume.
- the matrix density in the compacts was 1.77 g./cc. giving good thermal conductivity between the coated particles and the exterior of the compact.
- a production line operating on this principle has a number of adjacent stations through which the die blocks are passed in succession.
- a die block At a first station, a die block has its cavities filled with coated particles and matrix material (preferably overcoated on to the particles). Adjacent to the first station is the sliding entry door to a main oven so that a filled die block can be moved directly into the oven maintained at 320 C.
- the temperature of the die block measures 150 C. platens within the oven force the plungers into the dies at the requisite pressure and the plungers are locked in position. In the next die position, the temperature of the block rises to 250 C., to cure the resin.
- a method of making pressed compacts of nuclear fuel residing in preparing a mixture including fission product retaining fuel particles, a solid polymerisable resin and a granular matrix material, loading a die cavity with the mixture, heating the die and contents of the cavity so that a uniform temperature exists throughout the contents, being a temperature at which the resin melts but does not suffer a. change in chemical structure and together with the matrix material exhibits a uniform plasticity, and pressing the contents of the cavity in the die whilst at that even temperature condition so that the die contents are compacted throughout the die cavity.
- a method of making pressed compacts of nuclear fuel as claimed in claim 1 in which a die having multiple cavities is employed and the heating of the die and the contents of the cavities is carried out at a slow rate.
- a method as claimed in claim 1 including the steps of charging the mixture into a plurality of die cavities in a die block, closing each of the cavities and heating the block slowly and uniformly in an oven to about C.
- a method as claimed in claim 7 which resides in placing the heated die block between the thermally insulated platens of a press and operating the latter to press the contents of all the die cavities simultaneously.
- a method as claimed in claim 8 in which, after pressing, the die cavities are maintained closed whilst the block is further heated to cure the resin.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Ceramic Products (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB5427870 | 1970-11-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3845178A true US3845178A (en) | 1974-10-29 |
Family
ID=10470484
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00194488A Expired - Lifetime US3845178A (en) | 1970-11-13 | 1971-11-01 | Manufacture of fuel for nuclear reactors utilizing a polymerisable resin |
Country Status (9)
Country | Link |
---|---|
US (1) | US3845178A (xx) |
JP (1) | JPS5629238B1 (xx) |
BE (1) | BE774950A (xx) |
DE (1) | DE2154622A1 (xx) |
FR (1) | FR2113885B1 (xx) |
GB (1) | GB1327786A (xx) |
IT (1) | IT944811B (xx) |
LU (1) | LU64240A1 (xx) |
NL (1) | NL7115018A (xx) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3960994A (en) * | 1974-11-26 | 1976-06-01 | The United States Of America As Represented By The United States Energy Research And Development Administration | Preparation of high temperature gas-cooled reactor fuel element |
US3975471A (en) * | 1973-07-27 | 1976-08-17 | Hobeg Hochtemperaturreaktor-Brennelement Gmbh | Process for the production of fuel combined articles for addition in block shaped high temperature fuel elements |
US4140738A (en) * | 1976-03-08 | 1979-02-20 | Hobeg Hochtemperaturreaktor-Brennelement Gmbh | Process for the production of block fuel elements for high temperature reactors |
US4202793A (en) * | 1973-10-26 | 1980-05-13 | Agip Nucleare S.P.A. | Production of microspheres of thorium oxide, uranium oxide and plutonium oxide and their mixtures containing carbon |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0534065A1 (en) * | 1991-09-23 | 1993-03-31 | Combustion Engineering, Inc. | Application of frequency analysis to determine fuel pellet characteristics and acceptance |
FR3143365A1 (fr) | 2022-12-19 | 2024-06-21 | L V M H Recherche | Composition anti-age avec extraits de bourgeons et petales de roses et peptide |
-
1971
- 1971-10-25 GB GB5427870A patent/GB1327786A/en not_active Expired
- 1971-10-29 DE DE19712154622 patent/DE2154622A1/de active Pending
- 1971-11-01 NL NL7115018A patent/NL7115018A/xx unknown
- 1971-11-01 US US00194488A patent/US3845178A/en not_active Expired - Lifetime
- 1971-11-05 BE BE774950A patent/BE774950A/xx unknown
- 1971-11-08 IT IT53939/71A patent/IT944811B/it active
- 1971-11-09 FR FR7140163A patent/FR2113885B1/fr not_active Expired
- 1971-11-11 LU LU64240D patent/LU64240A1/xx unknown
- 1971-11-13 JP JP9105271A patent/JPS5629238B1/ja active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3975471A (en) * | 1973-07-27 | 1976-08-17 | Hobeg Hochtemperaturreaktor-Brennelement Gmbh | Process for the production of fuel combined articles for addition in block shaped high temperature fuel elements |
US4202793A (en) * | 1973-10-26 | 1980-05-13 | Agip Nucleare S.P.A. | Production of microspheres of thorium oxide, uranium oxide and plutonium oxide and their mixtures containing carbon |
US3960994A (en) * | 1974-11-26 | 1976-06-01 | The United States Of America As Represented By The United States Energy Research And Development Administration | Preparation of high temperature gas-cooled reactor fuel element |
US4140738A (en) * | 1976-03-08 | 1979-02-20 | Hobeg Hochtemperaturreaktor-Brennelement Gmbh | Process for the production of block fuel elements for high temperature reactors |
Also Published As
Publication number | Publication date |
---|---|
NL7115018A (xx) | 1972-05-16 |
IT944811B (it) | 1973-04-20 |
BE774950A (fr) | 1972-03-01 |
LU64240A1 (xx) | 1972-06-02 |
JPS5629238B1 (xx) | 1981-07-07 |
DE2154622A1 (de) | 1972-05-18 |
GB1327786A (en) | 1973-08-22 |
FR2113885B1 (xx) | 1974-05-31 |
FR2113885A1 (xx) | 1972-06-30 |
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