FR2463971A1 - PROCESS FOR THE SOLIDIFICATION OF BIOLOGICALLY HARMFUL WASTE - Google Patents

Abstract

A.PROCEDE FOR THE SOLIDIFICATION AND COMPACTION OF BIOLOGICALLY HARMFUL WASTE, IN PARTICULAR RADIO-ACTIVE, SOLID OR SOLIDIFIED, BY PRESSING. B. PROCESS CHARACTERIZED IN THAT THE WASTE IS TRANSFERED TO A MATRIX AND TRANSFORMED BY BRUSH COMPACTION IN 3 TO 500 THOUSANDS OF A SECOND IN PRESSED PIECES. C. PROCESS APPLICABLE IN PARTICULAR TO RADIO-ACTIVE WASTE FOR SAFE STORAGE.

Description

The invention relates to a process for the solidification and

  compaction of biologically harmful waste,

  in particular radioactive, solid or solidified, by pressing.

  A necessary condition for the intermediate and final disposal of biologically harmful wastes, in particular radioactive wastes, is their incorporation into a

  lixiviation resistant matrix and good thermal conductive

  than. It is therefore desirable to obtain as large a volume reduction as possible for this often very bulky waste, in order to reach a favorable economic and technical ratio between the quantity of waste.

incorporated and the matrix.

  A series of processes is known for the compaction of solid or highly radioactive solid waste, the choice of the process being essentially a function of the strength of the activity. Among these compaction processes, the incorporation of the waste in glass beads or their pressing into pellets or "pellets", which are impregnated

  of polymerizable monomers of plastics material.

  All of these methods are expensive mainly because of the need for remote-control operations that is difficult with bulky devices. They also require a relatively constant quality of the waste, both with regard to theomokenity and the fluidity which must

to be good.

  But in practice we are not always in the presence of a constant quality of waste. This is how

  for example, radioactive dissolution residues are obtained.

  high activity, heterogeneous and non-fluid, during the grinding and dissolving of irradiated fuel elements for reprocessing, these residues to be compact and

  embedded in a matrix. These dissolution residues contain

  metal flakes and chips, corrosion products, cutting and grinding residues, as well as residues of fuel elements containing small quantities of

uranium and plutonium.

  The object of the invention is to propose a process for the solidification and compaction of biologically harmful waste, in particular radioactive, solid or solidified, by pressing, which is independent of homogeneity.

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  and fluidity of waste and that can be implemented simply. For this purpose, the process of the invention is characterized in that the waste is transferred into a matrix and converted by abrupt compaction in 3 to 500 milligrams.

  my second in pieces pressed.

  It has been found that biological waste-

  They can be introduced into a steel matrix and compacted by rough pressing, in a pressed piece, the compacting and expelling processes of the pressed piece after compacting taking place in a few minutes. thousandths of a second. Compaction is preferably carried out in 3 to 50 thousandths of a second. It is advantageous to operate at temperatures below 23000 C and pressures above 1000 kg / cm 2. A considerable advantage of the process according to the invention consists in a high flow rate per unit time, as a result of the extremely short duration of compaction. and expulsion. These fast rates make it possible to work for high flows in quantity of waste, with relatively small pressed parts. Thus, small pressing dies and space-saving drive mechanisms are sufficient to achieve compaction, these devices being easy to shield and minimizing contamination. There is no requirement regarding the fluidity of the

  material. We can transform any substance, having a

  any degree, as long as it is dry.

  It is also partly advantageous to compact the press piece with a density of more than 40% of

  the theoretical density, by the method of the invention.

  The invention will be better understood using

examples described below.

  As a typical substance of highly waste

  radioactive material, a mixture of non-flowable powders

  of uranium oxide, aluminum oxide, zirconium dioxide,

  nium, molybdenum powder and zircon chips, various compositions. These mixtures are introduced into a steel matrix 8 mm in diameter and compacted by means of a hammer under pressure of 8000 kg / cm. Immediately afterwards, they are expunged, so that the overall process takes place in less

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  of 5 thousandths of a second. After the expulsion, the pressed piece has a diameter of 8 mm, a height of 10 mm, with a

  density of more than 90% of the theoretical density.

  In another example, the mixture of powders according to Example 1 is heated before compacting at 12000 C, and then pressed as in the previous example. The pressed pieces then have a density greater than 95% of the

theoretical density.

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Claims (5)

  1.- Process for the solidification and compaction of biologically harmful waste, in particular radioactive, solid or solidified, by pressing, characterized in that the waste is transferred into a matrix and converted by abrupt compaction in 3 to 500 thousandths of seconds in pressed pieces.   2. Method according to claim 1, characterized in that the compaction takes place in the space of 3 to 50 thousandths of a second.   3.- Method according to one of the claims   1 and 2, characterized in that the compaction takes place at temperatures below 2300 C. 4.- Process according to any one of   Claims 1 to 3, characterized in that the pressure   work is greater than 1000 kg / cm.   5. Process according to any one of   Claims 1 to 4, characterized in that the blank is   compacted with a density greater than 40% of the density theoretical.