EP0230740A2 - Installation et procédé de chauffage d'un conteneur ou de frittage - Google Patents

Installation et procédé de chauffage d'un conteneur ou de frittage Download PDF

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Publication number
EP0230740A2
EP0230740A2 EP86309627A EP86309627A EP0230740A2 EP 0230740 A2 EP0230740 A2 EP 0230740A2 EP 86309627 A EP86309627 A EP 86309627A EP 86309627 A EP86309627 A EP 86309627A EP 0230740 A2 EP0230740 A2 EP 0230740A2
Authority
EP
European Patent Office
Prior art keywords
container
furnace
containers
stack
support base
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Withdrawn
Application number
EP86309627A
Other languages
German (de)
English (en)
Other versions
EP0230740A3 (fr
Inventor
Eric John Ramm
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Australian National University
Australian Nuclear Science and Technology Organization
Original Assignee
Australian Atomic Energy Commission
Australian National University
Australian Nuclear Science and Technology Organization
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from AU65790/86A external-priority patent/AU588066B2/en
Application filed by Australian Atomic Energy Commission, Australian National University, Australian Nuclear Science and Technology Organization filed Critical Australian Atomic Energy Commission
Publication of EP0230740A2 publication Critical patent/EP0230740A2/fr
Publication of EP0230740A3 publication Critical patent/EP0230740A3/fr
Withdrawn legal-status Critical Current

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    • 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
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/34—Disposal of solid waste
    • G21F9/36—Disposal of solid waste by packaging; by baling

Definitions

  • the present invention relates to the heating of containers and is more particularly concerned with the heating of heat resistant metal containers carrying supply material incorporating radioactive waste and adapted to be immobilised in the container for subsequent long term storage.
  • the containers may contain synthetic rock precursor impregnated with high level radioactive waste.
  • the invention may be applied to other arrangements involving other forms of supply material such as metal powder and ceramic powders generally. This specification will describe the present invention with particular reference to the immobilisation of high level radioactive waste in which the utmost safety of storage is required; however, it will be appreciated that the invention may be applied to other forms of waste if desired.
  • One important application of the invention is to the preheating of containers before the containers are compressed at high temperature for an extended period of time so that the volume of the container substantially reduces and the contents densify.
  • the supply material comprises a ceramic powder for forming synthetic rock
  • the radioactive waste material is immobilised in the synthetic rock which has a density close to its maximum theoretical density.
  • Typical process conditions for the formation of suitable synthetic rocks are temperatures in the range 1 0 50 to 1260 o C, pressures in the range 5 to 30 MPa and pressing times in the range 1 to 3 hours.
  • temperatures in the range 1 0 50 to 1260 o C are temperatures in the range 1 0 50 to 1260 o C, pressures in the range 5 to 30 MPa and pressing times in the range 1 to 3 hours.
  • the present applicants have discovered that it is necessary to achieve a generally uniform temperature through the container and its contents before the hot pressing step can commence and typically the pre -heating time will be several times longer than the time needed for the hot pressing step.
  • any process for the immobilisation of high level radioactive waste must be conducted in an active cell which is a very expensive capital structure.
  • Hydraulic presses suitable for hot uniaxial pressing of bellows like containers are large and expensive capital items and an apparatus for a hot isostatic process is even more complex and bulky. Therefore, to maximise plant throughput it is desirable to minimise the residence time of a container in the press apparatus of whichever type is chosen, and in one aspect the present invention is concerned with an effective pre heating arrangement suitable for any hot pressing process (including hot isostatic pressing) involving radioactive waste containing supply material in a heat resistent metal container. In another aspect the invention can be used in a sintering process.
  • the heat resistent metal containers previously proposed have relatively thin walls and even the most suitable metals available have relatively low strength at the temperatures approaching and in the range applicable to processes with which the present invention is concerned. This is specially the case where the invention is applied to synthetic rock pressing operations. There is therefore an intrinsic mechanical handling problem for heated containers, and bearing in mind the extremely high reliability required for an active cell operation, there has been difficulty in conceiving an apparatus and process for effective heating and handling of containers.
  • an apparatus for heating heat resistant metal containers having therein supply material incorporating radioactive waste, each container having a gas discharge pipe and being arranged to be supported on a rigid support base which permits mechanical handling of the base and container, the mechanical handling including the formation of a stack of containers each supported on respective rigid support bases, the apparatus comprising
  • Use of the invention can permit an efficient and cost effective process to be constructed and operated in an active cell.
  • the rigid support base for each container mechanical handling is facilitated particularly when the container is heated and very reliable transfer is provided.
  • use of the invention deals with the problem of gases discharged from the contents of the container; these gases may include noxious gases and minor proportions of radioactive gases from volatile components of the high level waste. The gases must be collected and processed.
  • the invention facilitates implementation in a relatively simple manner with low maintenance requirements and any maintenance is possible with remote manipulators.
  • the apparatus and process can be confined to a compact physical space which is very important in terms of capital costs.
  • the invention permits a process to be implemented in which safe and reliable containment of the material can be provided.
  • One application of the invention is to provide a methof of sintering in containers in which cold pre-compacted blocks are provided, the blocks consisting of a ceramic powder impregnated with radioactive waste.
  • Use of the apparatus permits effective handling and sintering at very high temperatures e.g. of the order 1,200°C. Sintering is a process where under elevated temperature conditions the particles of matter form a dense ceramic material in which the radioactive waste is immobilised.
  • An important application of the invention is to the case where the waste is high level waste in which volatile components at the operating temperatures must be processed. These components such as cesium and ruthenium can be effectively handled with an apparatus according to the invention as described above.
  • Another application of the invention is to the use of the apparatus for pre-heating containers for subsequent hot isostatic pressing.
  • the containers are of cylindrical form with a bellows like formation in the side wall to facilitate predictable compaction of the containers in the hot isostatic pressing process.
  • Yet another use of the apparatus embodying the invention is for the preheating of containers of cylindrical form having a bellows like side wall and which are adapted to be subjected to hot uniaxial pressing.
  • Processes using the invention may include the use of synthetic rock components for immobilising the waste or may include the use of a metal powder such as copper powder to form a dense matrix surrounding and incorporating the waste material.
  • the waste material could be concentrated high-level radioactive waste or could be spent fuel rods.
  • the arrangement is such that the support bbase for each container comprises a solid disc like base plate for supporting the base of the container and a downwardly projecting extension which functions to space the base plate above the next lower container in the stack or from any other support surface.
  • the support bbase for each container comprises a solid disc like base plate for supporting the base of the container and a downwardly projecting extension which functions to space the base plate above the next lower container in the stack or from any other support surface.
  • the invention is implemented in a manner which does not require the lifting means (such as a mechanical or hydraulic jack) to enter itself into the heating zone of the furnace.
  • the lifting means such as a mechanical or hydraulic jack
  • the furnace is in the form of an induction furnace having a metal susceptor sleeve and of a length typically equal to about four containers in a stack.
  • the susceptor sleeve provides a safety barrier in the event that a container should rupture during the heating stage. Thus, any spillage is contained in a small part of the apparatus capable of subsequent cleaning after cool down.
  • the invention is arranged to be implemented with the gas discharge pipe of each container being in the form of a laterally extending pipe.
  • the gas collection system comprises a gas manifold having a collection head of elongated generally U-shaped form extending vertically, so that the discharge pipes of the respective containers can be inserted within the U shaped member and move upwardly therethrough with a clearance fit.
  • a method for heating heat resistant metal containers having therein supply material incorporating radioactive waste in solid form, the supply material being adapted to form a matrix in which the waste is safely immobilised, and each container having a gas discharge pipe and being arranged to be supported on a rigid support base which permits mechanical handling of the base and container, the mechanical handling including the formation of a stack of containers each supported on respective rigid support bases, the method comprising
  • the method extends to the further step of allowing a short cooling period for the pre-heated container before it is inserted within the subsequent hot pressing apparatus, this step being carried out so that the skin temperature of the container drops rapidly e.g. from 1000 C to 750 C thereby gaining significant strength for increased safety in the mechanical handling steps, yet a substantially uniform high temperature of 1000°C or more is maintained through the body of the synthetic rock precursor or metal powder in the container. It has been found that an air blast for a short period of time e.g. of the order of 2 minutes is sufficient to lower the skin temperature so that manipulators can grip the periphery of the container, which has a thin metal wall, and transfer it reliably to a pressing apparatus.
  • each support base has a guide member which is correctly orientated before the container is placed on the support base, and the furnace includes upwardly extending guides which co-operate with the guide members to maintain correct alignment of the support bases and the containers thereon. This arrangement ensures that the gas pipes on the containers maintain a clearance fit relative to the manifold of the gas collection system.
  • a pre heating arrangement in accordance with an embodiment of the present invention together with a single press unit can provide a very high plant output in terms of processed material per unit time while keeping capital costs down and facilitating simplicity of apparatus design.
  • An advantageous embodiment of the invention applicable to the case where the containers are subjected to a hot pressing operation is one in which a secondary furnace is utilised of the same arrangement but operated in a reverse direction as a cooling furnace. This ensures a steady and slow rate of cool down which is particularly important to minimise the risk of cracking where synthetic rock is formed within the container.
  • each of the cylindrical containers has a bellows-like side wall and flat end walls with a laterally extending gas discharge pipe 11 near the base.
  • Each container has had supply material poured into the container and then closed at the upper end with a lid which is welded into position.
  • This supply material may comprise particulate synthetic rock precursor impregnated with radioactive high level waste or other radioactive waste such as spent fuel rods; alternatively the supply material may be a metal powder such as copper powder.
  • the density of the particulate matter can be up to 35% of the maximum theoretical density of the final synthetic rock.
  • a density of about 99% of the maximum theoretical density can be achieved.
  • Each container rests on a respective base unit 12 comprising a flat disc like base plate 13 with an integral cylindrical extension 14.
  • the container 10 can be formed from a corrosion resistant high strength alloy such as INCONEL 601 and the base unit 12 can be made from alloys such as INCO alloys MA754 or MA956.
  • the heating apparatus comprises a vertical induction furnace 15 adapted to contain within its heating zone a stack of four containers.
  • the furnace 15 comprises induction heating coils 16 and a cylindrical metal susceptor sleeve 17, preferably of a high temperature alloy such as INCONEL 601 metal.
  • a gas collection manifold 18 is provided and comprises an elongated port 19 of U shape in cross section, connection ducts 20 and a discharge pipe 21 connected to a suction system which includes filtering for radioactive components and other particles and a suitable off-gas system for removing any volatile products.
  • the port 19 is arranged to accommodate the discharge pipe 11 of each container with a clearance fit.
  • a retractable stdCJ. holder 22 and a screw jack 23 for receiving cold containers from a swinging manipulator 24 and for raising the container into the stack in the furnace.
  • a similar swinging manipulator is provided (but not shown in the drawing) for removing a heated container to an unloading station 25 from which the container can be collected for hot pressing operations.
  • the retractable holder 22 has a support arm 26 which, as shown in figure 2, has a forked head 27 which is thinner than the axial extent of the extension 14 and engages around the extension.
  • the arm 26 is pivotally mounted on a base 26A and pivotally connected at its mid-portion to a hydraulic ram 28. Normally the arm 26 supports the stack of containers but when the stack is supported on a new, lower cold container, as described below, the ram 28 can be actuated to swing the arm back to the position shown in dotted lines in Figure 1 thereby permitting the stack to be raised by operation of the jack 23.
  • the jack 23 comprises a motor drive M, a captive nut 29 and a screw column 30 at the top on which a cylindrical pad 31 is mounted and adapted to support a base 12 and its associated container 10A.
  • the susceptor sleeve 17 closely encircles a base 12, the susceptor sleeve having diametrically opposed ribs 33 which, with a clearance, align within corresponding grooves 34 on the opposite sides of the base 12.
  • Orientation of each container 10 is provided by placing the container on a turntable similar to turntable 32 shown in Figure 1, and rotating the turntable until the discharge pipe 11 engages a microswitch. thereby correctly orientating the container.
  • a support base 12 is placed on the turntable of supply station 32 and rotated until a sensor (not shown) senses the correct orientation of the grooves 34 in the side of the support base.
  • a manipulator grips the sides of the container 10 and transfers it onto the orientated support base as generally shown in Figure 1.
  • the forked manipulator 24 shown in Figure 1 is pivotally displaced to engage under the support base of the new container, the turntable of the support station 32 then being lowered slightly so that the container is supported on the manipulator 24 and the manipulator 24 pivotally displaced to move the container into the correct location below the existing stack of containers in the furnace.
  • Motor M is then actuated to raise the screw jack whereby the support base of the new container is engaged to permit pivotal retraction of the manipulator 24, subsequent action of the motor then raising the container 10A so that it abuts the bottom of the support base of the lowermost container in the furnace to take the weight of the stack.
  • the ram 28 is actuated to swing back the arm 26. Further operation of the motor raises the jack so that the stack of containers is advanced upwardly by one increment. The jack does not penetrate into the heated zone of the furnace. This action causes the uppermost container to be discharged through the top of the furnace for removal by a swinging manipulator similar to manipulator 24.
  • the jack can be raised initially so that there is a clearance for swinging the manipulator into position and the jack is then lowered slightly so that the topmost container is supported on the manipulator, which is then swung away to the unloading station 25.
  • this slight lowering action can be synchronised to follow the operation of the ram 28 to reinstate the arm 26 to the position shown in the drawing so that jack is lowered leaving the stack supported on the arm 26.
  • An airblast apparatus 35 is provided for lowering rapidly the skin temperature of the bellows container 10 at the unloading station 25 so that it can be gripped with a manipulator to be removed from its support base and loaded into a hot pressing station.
  • a container 40 suitable for sintering is illustrated.
  • This container has a plain cylindrical wall 41, a thick metal top cap 43 and a slotted thick base 44 welded to the thin cylindrical side wall.
  • Near the base of the cylindrical thin wall is an off-gas pipe 42.
  • the base has on opposite side recesses or slots 45 to permit the base directly to be picked up with a forked manipulator arm but when the containers are arranged in the stack the weight of the stack is transmitted through the cylindrical side wall.
  • Cold precompaction conveniently in a die, is effected and the pressed blocks of ceramic powder and radioactive waste are placed in respective containers and top cap applied to seal the container.

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Processing Of Solid Wastes (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Tunnel Furnaces (AREA)
  • Powder Metallurgy (AREA)
EP86309627A 1985-12-11 1986-12-10 Installation et procédé de chauffage d'un conteneur ou de frittage Withdrawn EP0230740A3 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPH381785 1985-12-11
AU3817/85 1985-12-11
AU65790/86A AU588066B2 (en) 1985-12-11 1986-11-27 Container heating arrangements

Publications (2)

Publication Number Publication Date
EP0230740A2 true EP0230740A2 (fr) 1987-08-05
EP0230740A3 EP0230740A3 (fr) 1989-08-09

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ID=25634902

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Application Number Title Priority Date Filing Date
EP86309627A Withdrawn EP0230740A3 (fr) 1985-12-11 1986-12-10 Installation et procédé de chauffage d'un conteneur ou de frittage

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EP (1) EP0230740A3 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825617A1 (fr) * 1996-08-20 1998-02-25 Doryokuro Kakunenryo Kaihatsu Jigyodan Procédé pour solidifier des déchets contenant de l'iode radioactive

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2041662A5 (en) * 1969-05-19 1971-01-29 Keramik Wtb Veb Fining of ceramics, esp in flat plate form
US4047886A (en) * 1975-11-24 1977-09-13 Commissariat A L'energie Atomique Furnace for the continuous sintering of pellets of ceramic nuclear fuel material
DE2941968A1 (de) * 1979-10-17 1981-04-30 Keller Ofenbau GmbH, 4530 Ibbenbüren Transportanlage in und an einem tunnelofen zum brennen von keramischem gut

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2041662A5 (en) * 1969-05-19 1971-01-29 Keramik Wtb Veb Fining of ceramics, esp in flat plate form
US4047886A (en) * 1975-11-24 1977-09-13 Commissariat A L'energie Atomique Furnace for the continuous sintering of pellets of ceramic nuclear fuel material
DE2941968A1 (de) * 1979-10-17 1981-04-30 Keller Ofenbau GmbH, 4530 Ibbenbüren Transportanlage in und an einem tunnelofen zum brennen von keramischem gut

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825617A1 (fr) * 1996-08-20 1998-02-25 Doryokuro Kakunenryo Kaihatsu Jigyodan Procédé pour solidifier des déchets contenant de l'iode radioactive
US5826203A (en) * 1996-08-20 1998-10-20 Doryokuro Kakunenryo Kaihatsu Jigyodan Method for solidifying waste containing radioactive iodine

Also Published As

Publication number Publication date
EP0230740A3 (fr) 1989-08-09

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