US4645624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Containment and densification of particulate material
Assignee: Australian Atomic Energy Commission
•
Filing: 1983-08-19
•
Granted: 1987-02-24
•
Expires: 2003-08-19
Abstract
Abstract Particulate material is poured into a container which is decay and heat resistant, the container is sealed and subjected to axial compression at elevated temperature to cause densification of the material, there being an arrangement for preventing substantial radially outward deformation of the container during compression. An important application is to immobilization of nuclear reactor waste in a synthetic rock structure formed during the high temperature compression step, and advantageously the containers are secured within an outer metal cannister for subsequent safe handling and disposal. An important embodiment includes a bellows container which advantageously is upwardly pressed into an inverted metal cannister restrained by an upper abutment, the bellows container becoming an interference fit within the metal cannister during the final portion of compression, but the bellows container wall itself being substantially sufficient to prevent gross outward deformation of the bellows container.
Inventors
- 👤 Eric J. Ramm
- 👤 Alfred E. Ringwood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:37
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/28; G21F9/34
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
203 words
An improvement in the method for forming solid block which includes synthetic rock in which radioactive waste is immobilized, the improvement comprising: (a) preparing a supply material comprising a minor proportion of radioactive waste and a material for forming the synthetic rock in sufficient quantity to immobilize said radioactive waste when the supply material is densified into a block; (b) selecting a heat resistant steel container which is heat and corrosion resistant to contain the supply material during the method, the container having a side wall extending around an axis of the container and including a bellows-like structure for preventing gross outward deformation during the method; (c) establishing a quantity of supply material in the container and arranging the container with the bellows-like structure free of surrounding (d) applying and maintaining for an extended time pressure along the axial direction of the container to compress the supply material while applying heat to maintain an elevated temperature to cause densification and the formation of a block of synthetic rock including the radioactive waste; and (e) either before or after said densification step, sealing the container with a cap whereby the sealed container is adapted to be placed in a suitable long term storage location.
Claim 2
Dependent Claim
203 words
An improvement in the method for forming solid block which includes synthetic rock in which radioactive waste is immobilized, the improvement comprising: (a) preparing a supply material comprising a minor proportion of radioactive waste and a material for forming the synthetic rock in sufficient quantity to immobilize said radioactive waste when the supply material is densified into a block; (b) selecting a heat resistant steel container which is heat and corrosion resistant to contain the supply material during the method, the container having a side wall extending around an axis of the container and including a bellows-like structure for preventing gross outward deformation during the method; (c) establishing a quantity of supply material in the container and arranging the container with the bellows-like structure free of surrounding (d) applying and maintaining for an extended time pressure along the axial direction of the container to compress the supply material while applying heat to maintain an elevated temperature to cause densification and the formation of a block of synthetic rock including the radioactive waste; and (e) either before or after said densification step, sealing the container with a cap whereby the sealed container is adapted to be placed in a suitable long term storage location.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1 wherein said bellows-like wall structure provided in the container comprises a series of convolutions extending from one axial end of the container to the other.
Claim 4
Dependent Claim
23 words
A method as claimed in claim 1, wherein the container and the cap are of metal and heat is applied by induction heating.
Claim 5
Dependent Claim
16 words
A method as claimed in claim 1, wherein the container has overall a substantially cylindrical configuration.
Claim 6
Dependent Claim
58 words
A method as claimed in claim 1 and including locating a tubular screen within the container which is of metal, leaving a space between the screen and the interior wall of the container, and pouring thermally insulating powder into said space before said supply material is poured into a zone within said tubular screen to fill the container.
Claim 7
Dependent Claim
65 words
A method as claimed in claim 1, wherein said container which is of metal is located within an outer cylinder and when the container is filled with supply material and closed with a cap, said pressure and heat is applied, the dimensions of said outer cylinder and container providing the container with a fit looser than an interference fit when compressed within the outer cylinder.
Claim 8
Dependent Claim
43 words
A method as claimed in claim 1, and comprising placing metal in contact with the supply material prior to the application of heat and pressure, said metal providing an oxygen potential for aiding incorporation of the nuclear reactor waste into the synthetic rock.
Claim 9
Dependent Claim
19 words
A method as claimed in claim 1, and comprising, as a preliminary step, forming the supply material into granules.
Claim 10
Dependent Claim
49 words
A method as claimed in claim 1 and including loading the supply material into thin-walled metal cans which will remain solid at the densification temperature but which deform upon densification of the supply material as it forms synthetic rock, the metal cans being loaded in sequence into the container.
Claim 11
Dependent Claim
43 words
A method as claimed in claim 1, wherein the container is of metal and of elongated cylindrical shape and said densification is effected in a series of zones in sequence extending from one end of the container by utilising electrical induction heating coils.
Claim 12
Dependent Claim
15 words
A method as claimed in claim 10 wherein the said heating zones overlap one another.
Claim 13
Dependent Claim
41 words
A method as claimed in claim 1, wherein the densification is effected at a temperature in the region of 1260° C. and at a pressure in the region of 7 MPA and for a time in the region of 3 hours.
Claim 14
Dependent Claim
21 words
A method according to claim 1 wherein said elevated temperature is at least in the region of 1100° to 1200° C.
Claim 15
Dependent Claim
17 words
A method according to claim 13 wherein the axial pressure is at least about 3000 lbs/sq. inch.
Claim 16
Dependent Claim
28 words
An improved method according to claim 1 in which the supply material is in a particulate form and the densification step produces about a 75% reduction in volume.
Claim 17
Independent Claim
167 words
A method of containing and densifying particulate supply material comprising radioactive waste and synthetic rock precursor material, the method comprising pouring the supply material into a heat resistant steel bellows container of generally cylindrical from with a side wall including a bellows-like formation and of heat and decay resistant material, closing the bellows container with a lid, placing the bellows container on an upwardly displaceable ram having a heat resistant surface portion, displacing the ram upwardly to press the bellows container against a fixed abutment with the bellows-like formation free of surrounding support, maintaining substantially axially pressure through the ram on the bellows container, applying heat and maintaining a sufficiently elevated temperature in the bellows container for a sufficient length of time to cause densification of said particulate supply material in the bellows container and axial compression of the bellows container, the arrangement being such that deformation of the bellows container occurs in its axial direction, and removing the bellows container after completion of the densification step.
Claim 18
Independent Claim
167 words
A method of containing and densifying particulate supply material comprising radioactive waste and synthetic rock precursor material, the method comprising pouring the supply material into a heat resistant steel bellows container of generally cylindrical from with a side wall including a bellows-like formation and of heat and decay resistant material, closing the bellows container with a lid, placing the bellows container on an upwardly displaceable ram having a heat resistant surface portion, displacing the ram upwardly to press the bellows container against a fixed abutment with the bellows-like formation free of surrounding support, maintaining substantially axially pressure through the ram on the bellows container, applying heat and maintaining a sufficiently elevated temperature in the bellows container for a sufficient length of time to cause densification of said particulate supply material in the bellows container and axial compression of the bellows container, the arrangement being such that deformation of the bellows container occurs in its axial direction, and removing the bellows container after completion of the densification step.
Claim 19
Dependent Claim
34 words
A method as claimed in claim 16, and wherein after closing the bellows container with a lid, a preliminary pre-heating thereof is effected substantially without the application of axial pressure to the bellows container.
Claim 20
Dependent Claim
82 words
A method as claimed in claim 17, wherein the bellows container is of metal and said pre-heating is by induction heating for a period of several hours to bring the bellows container and its contents substantially to a uniform temperature which is substantially elevated but sufficiently below the temperature to be achieved in the subsequent hot pressing step, said uniform temperature being selected such that the bellows container has significantly greater strength at the pre-heating temperature compared with the hot pressing temperature.
Claim 21
Dependent Claim
29 words
A method as claimed in claim 16, wherein said hot pressing step is conducted with the temperature of the bellows container and its contents brought to above 1200° C.
Claim 22
Dependent Claim
32 words
A method as claimed in claim 16, and wherein immediately after placing the lid on the bellows container an axial compression supplied to the bellows container, the temperature not exceeding 800° C.
Claim 23
Dependent Claim
26 words
A method as claimed in claim 20, and wherein the axial compression applied in the pressing step of claim 24 is at least 3000 lbs/sq. inch.
Claim 24
Dependent Claim
38 words
A method as claimed in claim 16, and wherein the supply material has a particle size not greater than 2 mm and is readily pourable, the supply material being produced by spraying a slurry into a rotary kiln.
Claim 25
Dependent Claim
19 words
A method as claimed in claim 16, and comprising using a refractory block incorporating inducton heating coils extending therethrough.
Claim 26
Dependent Claim
62 words
A method as claimed in claim 16, and including using a cylindrical partition within the bellows container and confining said supply material to the zone within said cylindrical partition, an alternative particulate material being located between said partition and the interior wall of the bellows container whereby the supply material is excluded from the convolutions of the wall of the bellows container.
Claim 27
Dependent Claim
21 words
A method according to claim 16 wherein said elevated temperature is at least in the region of 1100° to 1200° C.
Claim 28
Dependent Claim
18 words
A method according to claim 25 wherein the axial pressure is at least about 3000 lbs. sq. inch.
References Cited (Backward Citations)
US2885287A
Cited
US3000072A
Cited
US3160502A
Cited
US3213031A
Cited
US3383208A
Cited
US3340056A
Cited
US3935467A
Cited
US4058479A
Cited
JPS5273300A
Cited
DE2600790A1
Cited
FR2369659A1
Cited
US4172807A
Cited
US4192629A
Cited
US4209420A
Cited
DE2659691A1
Cited
US4115311A
Cited
JPS54116600A
Cited
US4280921A
Cited
EP0044381A1
Cited
US4409029A
Cited
EP0044692A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-23 | 1990-08-25 | 1991-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-23 | 1994-08-25 | 1995-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-23 | 1998-08-25 | 1999-02-24 | $7700.00 | Window Closed / Lapsed |