EP0186638A1 - A method in the storage of nuclear waste of intermediate-level radioactivity, deriving E.G. from nuclear power plants and a waste unit produced hereby - Google Patents

A method in the storage of nuclear waste of intermediate-level radioactivity, deriving E.G. from nuclear power plants and a waste unit produced hereby Download PDF

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Publication number
EP0186638A1
EP0186638A1 EP19850850353 EP85850353A EP0186638A1 EP 0186638 A1 EP0186638 A1 EP 0186638A1 EP 19850850353 EP19850850353 EP 19850850353 EP 85850353 A EP85850353 A EP 85850353A EP 0186638 A1 EP0186638 A1 EP 0186638A1
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EP
European Patent Office
Prior art keywords
waste
container
binder
mixture
lid
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Withdrawn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
EP19850850353
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German (de)
English (en)
French (fr)
Inventor
Sven Gunnar Brandberg
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Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0186638A1 publication Critical patent/EP0186638A1/en
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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
    • 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
    • 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
    • G21F9/30—Processing
    • G21F9/301—Processing by fixation in stable solid media
    • G21F9/302—Processing by fixation in stable solid media in an inorganic matrix
    • G21F9/304—Cement or cement-like matrix

Definitions

  • the present invention relates to a method in the storage of nuclear waste of intermediate-level radioactivity deriving e .g. from nuclear power plants, in which method a mixture of the waste and a liquid binding agent is charged to a container through an opening provided therein; the binder is allowed to solidify; the container opening is closed and sealed; and the container is optionally transported to a final or terminal storage site.
  • the invention also relates to a waste unit produced when carrying out the method according to the invention.
  • intermediate-level radioactive waste waste with which the level of radioactive radiation is so low that the waste can be shielded with the aid of relatively simple means and does not give rise to any appreciable increase in temperature.
  • waste should also contain mainly radioactive nuclides of moderate half-life. This means that the radiation emitted by the waste will decrease strongly during the first centuries.
  • the intermediate-level radioactive waste to a large extent comprises ion exchange masses used for cleansing various waterflows in the plant.
  • Another typical constituent of such wastes is salt concentrates resulting from the vaporization of contaminated solutions.
  • the normal method of handling this type of waste is to mix the waste with some substance or another, often cement, bitumen or a synthetic resin.
  • cement The most common binder used, and one which affords valuable advantages, is cement.
  • Cement is used in the following way; Waste in the form of a water-saturated ion exchange mass, or a concentrated salt solution, or in some cases a slurry, is mixed with a slurry of cement and water in suitable proportions. The mixture is poured into a container, which may have the form of a conventional 200-liter barrel or drum, or a prefabricated concrete vessel. When the mixture has solidified, the container is sealed with a lid of metal and cement, respectively.
  • the barrels, or concrete containers are often stored for some years in locations on the site on which they were filled.
  • the containers are then transported to a repository depot.
  • This repository depot may be a rock cavity located some ten of meters beneath ground level.
  • the containers are also in same instances stored in selected surface locations in an open trench, which is subsequently covered with soil or clay to a depth of some ten meters.
  • the waste comprises a mixture of many different substances which undergo changes. Examples of such changes include:
  • One object of the present invention is to provide a method in the storage of intermediate-level radioactive waste deriving e.g. from nuclear power plants and a waste unit produced in conjunction herewith, which enable a higher quantitative ratio to be used between waste and binder than that permitted with the known method, without increasing the safety risks.
  • Another object of the invention is to provide a method and a waste unit of the aforedescribed kind in which transportation of the nuclides of the waste by diffusion from the interior of the waste body (concrete mass) to its outer surface and out from the container to the surroundings is delayed and counter-acted to a greater extent than in the aforementioned known method and waste unit, at the same time as gas is able to leak from the container to an extent which prevents the build-up of harmful overpressures.
  • hydroaulic binder is recognized within the building material industry to designate a binder capable of hardening in the presence of water.
  • (Portland) cement is a prime example of conventional binders of this kind, although hydraulic lime and activated slags, such as, for instance, blast furnace slag activated with soda lye also fall under the designation "hydraulic binder”.
  • the container is sealed by casting a concrete lid or cover in position in the container opening.
  • a disk of highly porous concrete or a plate made of a metal or an alloy which can readily corrode in an alkaline environment can be placed nearest to the solidified mixture of waste and binder prior to casting the lid in place.
  • This plate is provided with a multiple of apertures through which gas can pass.
  • the lid is cast from a cement mixture which affords an extremely high resistance to outward diffusion of radioactive nuclides, and a plurality of pre-manufactured concrete cylinders of substantial gas-permeability are cast in the lid or cover to provide gas through-flow channels.
  • the container When casting the container in a concrete block in the re p osi- tory site, the container should be positioned so that the lid or cover faces downwards.
  • the waste unit according to the invention includes at least one substantially cylindrical container provided with a bottom and accommodating a mixture of intermediate-level radioactive waste derived e.g. from a nuclear power plant and a binder, and being provided with a seal or closure means, this waste unit being characterized in that
  • the container is preferably provided with means for holding the seal or closure means in position.
  • the seal or closure means comprises a concrete lid or cover cast in position in the container opening.
  • the seal or closure means may also include a highly porous concrete slab or a plate made of metal or alloy capable of readily corroding in an alkaline environment, and arranged between the mixture of waste and binder and the concrete lid.
  • the plate is provided with a plurality of apertures through which gas can pass.
  • the lid or cover may be cast from a cement mixture which affords an extremely high resistance to outward diffusion of radioactive nuclides, and may be provided with gas through-flow channels formed from a less impervious material.
  • Figures 1-4 are axial sectional views of a first, second, third and fourth embodiment, respectively, of a waste unit according to the invention.
  • the figures illustrate a cylindrical container 1 provided with an opening and manufactures from an iron material, for example unalloyed or plain steel, it having been ensured that the botton of the container and the container walls are gas tight. Located adjacent the container opening is a constriction 2.
  • the material from which the container 1 is formed has a thickness such that the container walls and bottom can be expected to remain impervious in prevailing environments for one thousand years.
  • the thickness of the material when using plain carbon steel is normally greater than 2 mm and less than 10 mm, preferably 3-6 mm.
  • waste deriving e.g. from a nuclear power plant has been mixed with a slurry of cement and water, and the mixture has been poured into the conatiner 1 and then allowed to solidify to a hard mixture 3 of waste and cement.
  • waste deriving e.g. from a nuclear power plant has been mixed with a slurry of cement and water, and the mixture has been poured into the conatiner 1 and then allowed to solidify to a hard mixture 3 of waste and cement.
  • no special requirements have to be placed on the quality of the solidified mixture.
  • volumetric ratio between waste and'binder in the mixture varies with the type of waste concerned and the container measurements. Normally, however, a volumetric ratio of waste to binder in the range of 1:1 - 1:10 is applied.
  • the size of the container is chosen with a view to the ease of handling the same on one hand and the desire to accommodate as much waste as possible on the other.
  • a diameter of 600 mm has been found a suitable compromise in this respect, together with a container height adapted to accommodate a waste-binder mixture to a height or depth of about 700 mm and the inclusion of a closure means or seal in accordance with the following:
  • the waste unit according to this embodiment presents considerable resistance to diffusion, but does not prevent the penetration of water other than when stored at shallow depths.
  • the majority of nuclides, however, have time to decay totally before having passed through the lid or cover.
  • the constriction- 2 serves as means for mechanically holding the lid 4 in the position in which it was cast.
  • FIG. 2 there is used a container which is about 100 mm taller than the container of the remaining embodiments. Subsequent to pouring the waste and cement mixture 3 into the container, a 200 mm thick slab 5 of highly porous concrete (aerated concrete) has been placed on top of the mixture 3. In addition hereto, a lid 4 has been cast in the manner described in Figure 1, the thickness of the lid, however, being 100 mm.
  • This construction prevents water from penetrating into and filling the pores of the mixture 3, even when the container is placed some tens of meters beneath ground level.
  • the waste unit illustrated in Figure 3 differs from the waste unit of Figure 1, insomuch as a perforated aluminium plate 6 having a plate thickness of 2 mm and a weight of 300 g has been placed over the waste and cement mixture 3 prior to casting the lid 4 in position.
  • the aluminium plate 6 When strongly alkaline cement water penetrates the container, the aluminium plate 6 corrodes relatively quickly to form hydrogen gas, which fills the pores in the mixture 3 and prevents water from penetrating into said pores.
  • the plate 6 can be made of any other metal or alloy having approximately the same corrosion properties as aluminium in alkaline environments.
  • the waste unit illustrated in Figure 4 conforms with the waste unit illustrated in Figure 1, with the exception of the design of the lid.
  • a lid or cover 7 has been cast from a cement mixture which provides an extremely impervious concrete having an effective diffusivity of about 10- 15 m 2 /s. This means that the possibility of pressure build-up in the container cannot be excluded, and hence counter measures must be taken.
  • this embodiment incorporates a plurality of pre-manufactured concrete cylinders 8 having a length of 210 mm and a diameter of 30 mm placed on the mixture (the waste body) 3, so as to be embedded in the lid 4, in the manner illustrated.
  • the cement mixture from which the cylinders 8 are made is such as to provide an effective diffusivity of about 10 -13 m 2 /s., thereby enabling the cylinders 8 to function as gas through-flow channels.
  • the number of cylinders 8 provided may vary in dependence on the type of waste to be stored. Normally, at least 5 cylinders are used, in an attempt to prevent an excessively wide gas through-flow surface becoming blocked simultaneously by chance should the waste unit be placed in the terminal-storage site in a less favourable manner.
  • the diffusivity is a measurement of the movement of ions in water under the influence of differences in concentration.
  • effective diffusivity is meant here movement of simple ions, such as chloride ions, through a porous body. It is defined by a law well known in physics, Fick's first law.
  • the effective diffusivity is normally established experimentally. Two containers containing mutually different concentrations of, for example, chloride ions, are separated by a thin porous slab comprising, for example the cement mixture to be examined. The flow of chloride ions through the slab is then determined, and the effective diffusivity calculated from the measurements obtained.
  • the major part of the lid may comprise a cement mixture which affords a more impervious concrete exhibiting a diffusivity of at least 10 -14 m 2 /s, and even more impervious concrete.
  • the diffusivity of the concrete may be regulated in a manner known per se, by selection of:
  • the filler may be sand of suitable particle size, together with additives or preferably comprises clays, such as bentonite, industrial silica, fly ash and other commercially available special products.
EP19850850353 1984-12-11 1985-10-31 A method in the storage of nuclear waste of intermediate-level radioactivity, deriving E.G. from nuclear power plants and a waste unit produced hereby Withdrawn EP0186638A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8406281A SE8406281L (sv) 1984-12-11 1984-12-11 Sett vid lagring av medelaktivt avfall fran kernkraftsanleggningar och avfallsenhet framstelld hervid
SE8406281 1984-12-11

Publications (1)

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EP0186638A1 true EP0186638A1 (en) 1986-07-02

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EP19850850353 Withdrawn EP0186638A1 (en) 1984-12-11 1985-10-31 A method in the storage of nuclear waste of intermediate-level radioactivity, deriving E.G. from nuclear power plants and a waste unit produced hereby

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1180579A2 (en) * 2000-08-10 2002-02-20 The Boeing Company Finger damper for turbine disk
ES2324255A1 (es) * 2007-01-08 2009-08-03 Albermarna, S.L. Procedimiento de inertizacion de depositos de combustibles.
JP2015184198A (ja) * 2014-03-25 2015-10-22 三菱重工業株式会社 汚染水の貯蔵装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2748774A1 (de) * 1977-10-31 1979-05-03 Nukem Gmbh Endlagergefaess fuer radioaktive abfaelle
GB2009486A (en) * 1977-09-01 1979-06-13 Central Electr Generat Board Treatment of radioactive sludge
DE3410370A1 (de) * 1983-03-22 1984-10-31 National Nuclear Corp. Ltd., London Verfahren und einrichtung fuer die beseitigung von radioaktiven abfaellen

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2009486A (en) * 1977-09-01 1979-06-13 Central Electr Generat Board Treatment of radioactive sludge
DE2748774A1 (de) * 1977-10-31 1979-05-03 Nukem Gmbh Endlagergefaess fuer radioaktive abfaelle
DE3410370A1 (de) * 1983-03-22 1984-10-31 National Nuclear Corp. Ltd., London Verfahren und einrichtung fuer die beseitigung von radioaktiven abfaellen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1180579A2 (en) * 2000-08-10 2002-02-20 The Boeing Company Finger damper for turbine disk
EP1180579A3 (en) * 2000-08-10 2003-12-17 The Boeing Company Finger damper for turbine disk
USRE39630E1 (en) 2000-08-10 2007-05-15 United Technologies Corporation Turbine blisk rim friction finger damper
ES2324255A1 (es) * 2007-01-08 2009-08-03 Albermarna, S.L. Procedimiento de inertizacion de depositos de combustibles.
JP2015184198A (ja) * 2014-03-25 2015-10-22 三菱重工業株式会社 汚染水の貯蔵装置

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Publication number Publication date
SE8406281L (sv) 1986-06-12
SE8406281D0 (sv) 1984-12-11

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