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
  • G21F5/06—Details of, or accessories to, the containers
  • G21F5/14—Devices for handling containers or shipping-casks, e.g. transporting devices loading and unloading, filling of containers
• • 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
• • 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
  • G21F7/00—Shielded cells or rooms
  • G21F7/005—Shielded passages through walls; Locks; Transferring devices between rooms

Definitions

• the invention relates to a method for transporting and storing radioactive materials, in particular reactor fuel elements.
• the method is mainly used for the interim storage of irradiated fuel elements before reprocessing.
• Various solutions have already been proposed for the interim storage of irradiated fuel elements. So it is known to store the fuel assemblies wet in a pool or to accommodate them in transport containers. in the In the first case, the fuel assembly of the reactor must either be enlarged for this purpose, or an equivalent storage device must be set up at a suitable location. With regard to safety, monitoring and handling, the same strict safety requirements are placed on such bearings as for the reactor itself. In the second case, the transport containers themselves already guarantee adequate security. They are also not opened at the depository, so that corresponding separate safety precautions at the depository can be saved. However, if a larger number of fuel elements have to be stored, the investment costs of the expensive transport containers are significant.
• a method should therefore be found which permits the relatively compact storage of the spent fuel elements without incurring great costs for monitoring and handling facilities in the storage facility and without having to use a large number of expensive transport containers.
• the method according to the invention fulfills these requirements. It is characterized in that the radioactive materials in a hermetically sealable, chemical made of resistant material, that the storage container is in turn inserted into a mechanical, thermal and radiation protection transport container, that the latter is transported to a storage location, and that the storage container is removed from the transport container at the storage location ⁇ removed and inserted for storage in a concrete silo which ensures radiation protection.
• the device for carrying out the method according to the invention comprises the following parts:
• a transport container 17 a hermetically closable storage container 7 for the radioactive materials which can be hermetically sealed; a concrete shaft 18 for receiving the transport container 17 when unloading the storage container 7; a protective container 20 for receiving and transferring the storage container 7 from the concrete shaft 8 to the storage location 41 and a number of concrete silos 12 for receiving the storage container 7 for storage.
• the most important component of the device according to the invention is the storage container. In summary, it must meet the following conditions:
• FIG. 1 shows a longitudinal section through a transport container with a storage container accommodated therein
• FIG. 1a shows detail Ia from FIG. 1, on a larger scale
• FIG. 2 shows a cross section along the line II-II through the •
• FIG 3 shows schematically the transport container which is being prepared for the unloading of the storage container
• Fig. 5 shows schematically the lifting out of the storage container the transport container and pulling the storage container into the protective container
• Fig. 8 schematically shows another embodiment variant of a
• FIG. 10 shows a helium detector for checking the tightness of the storage containers.
• the transport container 17 shown in FIG. 1 consists of a solid steel cylinder 31. '' which ensures adequate shielding against gamma rays.
• the transport container 17 is forged in one piece, so that between the steel cylinder 31 and the container bottom 32 only a single weld 33 is required.
• Cooling fins 34 are arranged outside the steel cylinder 31.
• the transport container 17 is closed with a tamper-proof and tightly closing lid 19.
• trunnions 35 are attached at various points and removable shock absorbers 16 are mounted on both ends of the container 17.
• the transport container described is an embodiment which can normally be loaded with 12 fuel elements. In the present case, however, the transport container is loaded with a storage container.
• This storage container 7 has a stainless steel jacket 36 for seven pressurized water reactor fuel elements. The wall thickness of the jacket is approximately 15 mm.
• the lid 1 of the storage container is fastened to the casing by means of screws 2.
• the protruding lips 3 between the cover flange 37 and the jacket flange 38 are welded together.
• Ribs 4 are attached over the length of the storage container, which ensure the heat emission to the transport container or to the environment.
• Steel ribs 5 are welded to the bottom 39 and to the lid 1, which have a stiffening effect and also serve to dissipate heat. All ribs 4, 5 act
• the cover 1 While the lips 3 are being welded, the cover 1 is not yet screwed onto the jacket 36, so that the screw bolts 2 do not hinder the welding.
• the container 7 is first evacuated through the valve 6. The external pressure presses the cover 1 onto the jacket flange 38. A seal 9 helps to maintain the vacuum.
• the container is pressed out with helium at a pressure of approx. 7 atm and the tightness of the container is checked with helium detectors 40 (FIG. 10).
• the excess pressure in the container filled with helium is left and an end cover 8 is welded on via the filling valve 6.
• the pressurized storage container 7 is thus hermetically sealed.
• the operations described are carried out in the reverse order. After the welding seam has been ground off, the sealing cover 8 is removed, the helium pressure is released from the container and the vacuum is established. Subsequently
• the fuel elements are surrounded by boron steel boxes 11 in the storage container. Normally, the storage container is always dry, but the distance between the boxes 11 and their borrow stop ensure the sufficient subcriticality even when filling with water.
• the space between the boxes 11. is filled with disc-shaped cast aluminum bodies. These cast aluminum bodies give the configuration “great stability in the event of an accident, they slow down the fast neutrons somewhat, absorb some of the gamma rays and dissipate the decay heat of the fuel elements to the wall of the rotary storage compartment.
• the loading and closing of the storage container must be carried out in protected and controlled rooms, ideally in the immediate vicinity of the reactor.
• the necessary remote-controlled devices must also be available here.
• the dimensions of the storage container for seven pressurized water reactor fuel elements are selected such that they fit straight into the usual transport container, which normally has space for 12 fuel elements.
• the storage container is thus loaded into the transport container and transported to the interim storage facility. During transport, all safety-related regulations and requirements, such as mechanical strength, thermal properties and radiation protection conditions, are met by the transport container.
• the actual intermediate storage consists of a concrete slab 41, in which cylindrical recesses or silos 12 for the storage containers 7 are embedded (FIGS. 6, 7).
• the inner walls of the silos 12 are expediently covered with a steel lining.
• the storage containers are cooled by free convection of the ambient air.
• the fresh air is supplied through ducts 13 below the storage position.
• the heated air rises through baffles 14, which prevent the gamma rays from escaping, through the concrete cover 15 to the outside.
• FIGS. 3-6 OMPI are illustrated in FIGS. 3-6.
• the transport container 17 is let down into a concrete shaft 18 (FIG. 4). Now the cover 19 is lifted off and removed from the silo so that the protective container 20 can be placed on the transport container 17.
• a lifting plate 22, which is arranged in the interior of the protective container is lowered and rotated with the lifting tabs 23 of the storage container 7.
• the storage container 7 is pulled up into the protective container 20 and the slide valve 21 is pushed in again.
• the protective container 20 provides sufficient protection against the radiation from the storage container 7 so that it can be lifted out of the concrete shaft 18.
• the protective container is then transported to the storage location.
• Environmental pollution from the interim storage facility is possible in three different ways: through direct radiation, through leaks in the fuel jacket combined with damage, or leaks in the storage containers and through activation of the cooling air by the fast neutrons.
• the thick concrete wall with added boron forms a sufficient barrier against direct radiation (primary gamma radiation, neutron radiation and secondary gamma radiation after neutron capture).
• the tightness of the storage containers is checked by the monitoring system with helium detectors.
• the activation of the air can be kept largely harmless if the cold supply air is free of dust. In this way, no dust particles can be deposited on the storage container, activated there, and entrained again by the cooling air.
• the interim storage facility including the cranes can be covered with ei ⁇ ner ordinary Hall, which does not however hinder the free exit of hot air the usual protection 'against atmospheric conditions (crosswind with dust supply, rain, snow) should ensure.
• the massive concrete structure of the interim storage facility offers sufficient protection against all mechanical influences (earthquake, plane crash, etc.).
• a grid 26 of plastic pipes is laid over the concrete cover 15 of the concrete silo 12. One branch each from the pipes in both directions penetrates into the air outlet openings of the concrete cover 15 without, however, impairing the free air outlet.
• a central suction fan 27 ensures constant negative pressure in the pipes.
• a scanning control device 43 periodically opens one of the valves 44 against the suction pump 27 of the helium detector 40 one after the other.
• a defective storage container can thus be found within a scanning cycle.
• Such a loading Containers must be removed from the silo and transported back to the loading or unloading location. Leakage from a storage container does not mean that there is no activity, since undamaged fuel elements are stored in the interim storage facility.
• the helium filling of the storage casks excludes any chemical damage to the fuel assemblies during the storage period.
• the fuel is therefore protected by a double mechanical barrier.
• the second purely mechanical barrier can easily be expanded to a further barrier against mass transfer.
• the air channels in the cover 15 are omitted.
• the cooling air flow of the storage container, together with the cooling air of the concrete from the channels 28, circulates in a closed circuit.
• the recooling takes place in additional vertical shafts 29 with vertical heat pipes 30 with heat exchangers 5 arranged at the top.
• the escape of the circulating air into the workshop located above the warehouse is avoided by the suction blowers 27 of the leakage monitoring system which generate a vacuum.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Packages (AREA)
• Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4273185

Family Applications (1)

Country Status (10)

Cited By (5)

Families Citing this family (1)

Citations (7)

• 1979
  • 1979-05-07 CH CH428179A patent/CH637499A5/de not_active IP Right Cessation
• 1980
  • 1980-04-28 FI FI801374A patent/FI801374A/fi not_active Application Discontinuation
  • 1980-05-06 WO PCT/CH1980/000053 patent/WO1980002469A1/de active IP Right Grant
  • 1980-05-06 BR BR8008674A patent/BR8008674A/pt unknown
  • 1980-05-06 DE DE8080900762T patent/DE3064891D1/de not_active Expired
  • 1980-05-06 AT AT80900762T patent/ATE4755T1/de not_active IP Right Cessation
  • 1980-05-06 JP JP50093380A patent/JPS56500584A/ja active Pending
  • 1980-05-06 HU HU801105A patent/HU182080B/hu unknown
  • 1980-05-07 DD DD80220934A patent/DD151527A5/de unknown
  • 1980-11-17 EP EP80900762A patent/EP0028222B1/de not_active Expired

Patent Citations (7)

Non-Patent Citations (1)

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