DE1127508B - Process and device for solidifying aqueous nuclear waste - Google Patents

Description

GERMAN

PATENT OFFICE

INTERNAT. KL.

G 21

A35632Vnic / 21g

REGISTRATION DATE: SEPTEMBER 22, 1960

NOTICE THE REGISTRATION AND ISSUE OF THE

Publication: 12. A P RIL 1962

The disposal of radioactive, aqueous nuclear waste is becoming more and more important because it is at the growing incidence of such wastewater is not always possible, it can be harmed simply by diluting it close. One is therefore more and more about to solidify the nuclear waste liquids to sink the bodies formed in this way into the sea or to bury them with a minimum of risk. To solidify, one has to melt the previously concentrated radioactive waste with glass formers, the sintering of those enriched in ion exchangers. or in silicate Toning picked up waste by ceramic fire or the absorption of the radiating liquid suggested in cement with subsequent hydraulic setting.

It is an object of the invention to overcome certain shortcomings and difficulties inherent in these various methods to eliminate or at least eliminate when handling the aids and materials used to be reduced to a tolerable level and the final destined for sinking or burying Molded bodies in which the hazardous waste is bound without awkward and the environment dangerous measures to give a maximum of security against the dangerous substances be leached after sinking or burial of the receiving body.

About the difficulties mentioned, which arise in the selective absorption of radiating cations in Set the toning of the montmorillonite group with subsequent ceramic firing, and above all that occur in the handling of the dangerous highly active substance in appearance, reported z. B. a work by Kunkel in the magazine "Atompraxis", Vol. II, 1956, pp. 272 to 274 (see especially p. 273, left column, and p. 274, left column below to right column above). In another paper by Amphlett on the treatment of high-level waste in the magazine "Atomics", Vol. 8, 1957, p. 116 bis 120, the conversion of such waste into solid, non-leachable form is discussed, and it is over reported the difficulties arising with the local combustion processes (cf. in particular p. 118, unke Column, paragraphs 1 and 2, and middle column in the middle of paragraph 2, as well as p. 119, right column, paragraph 1). With the methods discussed there, on the one hand solidification by melting together the previously dewatered and concentrated waste with flux to vitreous masses and on the other hand ceramic firing of the waste previously mixed with clays containing silicate are special advantages ears and device for solidifying aqueous nuclear waste

Applicant:

Rudolf Alberti,
St. Andreasberg (Harz), laundry ground 463

Rudolf Alberti, St. Andreasberg (Harz),
has been named as the inventor

Visual measures are required to avoid any risk to workers during the preparatory steps mentioned to avoid so that ζ. Β. remote control must be used (see p. 119, middle column below).

Such precautionary measures are largely unnecessary, if one is to dispose of the aqueous isotopic wastes taking up in pure cement or concrete mixes, in which suitable measures ensure that they are evenly distributed in the intake mixture can be achieved automatically and without the need to stir. Since the however, hydraulically set blocks created with the radiant mixing water as a result of them Solidification by cold means does not always have the freedom from pores, which is desirable for resistance to leaching, so one already has the set blocks are subsequently impregnated with a pore-filling, self-curing plastic.

In contrast, instead of such a plastic impregnation, a method for solidifying aqueous nuclear waste, in which the radiating waste water is absorbed by a hydraulic binder and made to set, according to of the invention first used a refractory cement as a hydraulic binder and then the set block in a manner known per se by means of a ceramic fire to prevent leaching solid sintered body compacted. In this two-stage process, the block is thus after the one in the first The setting that has taken place in preparation for the second (compaction) stage is carried out first Preheat dehydrated in a drying oven and then burned sharply.

209 55Ϊ / 443

In this way, the relief given when using the hydraulic consolidation method can be achieved and advantages in the extensive elimination of operating hazards during the preparatory measures to solidify the waste lie, combine with the security that a final Firing that provides pre-solidified blocks for their resistance to leaching. The shortcomings that have so far been working with burning

Incinerated waste concrete. Because removing the funnel after filling and loosening it of the tied body from the container would be associated with radiation hazards and one would do this If parts are better combined with the block, the loss is insignificant when using the cheap plastic. Such plastic receptacles that come out of the container with the filling funnel and distribution tube inserted exist are due to their simple

Methods of atomic solidification due to the ι ο unity and easy applicability, their economically difficult and dangerous preparatory measures borrowed production and their low shipping weight adhere, as well as those with only hydraulic tes suitable, the described method of atomic solidification sometimes existing uncertainty due to garbage disposal wide areas of application to a lack of numbers The new method 15 opens up pore-free blocks in order to avoid leaching in rich fields of technology and science. Another advantage of using a similarly resolved: In the first phase, the combustible container is darm that the drainage of the preparatory work to be carried out before the advantages of hydraulic block formation for the sharp fire is exploited, compared to the hardened molded body by preheating, mentioned MontmorÜlonitverfahren z. B. is made easier if the outer shell quickly verder advantage that the mixing is omitted and that shrinks in the 20 and the escaping water vapors drying oven already a solidified material and. no longer presents an obstacle. The finished fired no semi-liquid porridge comes, and in the second
The advantages for the extensive protection against leaching by the sintering of the phase become the first phase
Tied blocks exploited.

It is recommended that the refractory cement used to absorb the radiant waste liquid be used
refractory aggregates such as fireclay or brick chippings,
to add. This increases the strength of the set concrete block and allows it to be handled up to 30
relieved for the subsequent fire. Appropriate
is to use these aggregates in a largely isodisperse grain size, which means by far
most of the grain sizes are within fairly narrow limits, e.g. B. between 1.5 and 3 mm. Such a 35 of the invention is described. In the drawing, the distribution of the skeleton formers in the concrete mix is shown in FIG. 1, a schematic sectional view of a structure

facilitates the even suction of the wastewater to be absorbed, which is expediently from is introduced into the intake mixture at the bottom. If you also want the total radiation of the to be formed Reduce blocks by, according to the teaching of German patent specification 1053 686, the absorbing substance substances with high radiation absorption capacity, such as Barite, adds, so becomes the above

This surcharge also gives reasons for the refractory 45 surcharges. From this mixture one allows the ment expediently added as isodisperse grains. eliminating liquid in the form of a solution or

Molded body then reveals at most small residues of the plastic parts of the filling device. One solid shell, as it is only hydraulically hardened, Shaped bodies intended to be countersunk or buried in the interests of transport security was sometimes desired, the sintered concrete body compacted by the subsequent fire is required anyway not.

Such a sinking body can have a cylindrical shape or a square cross-section have, which is sometimes advantageous for stacking a plurality of such bodies together.

The following are some exemplary embodiments

acceptance device made of plastic, including a top view, Fig. 2 is a manufactured with the help of this device atomic waste-containing fired sintered concrete body and Fig. 3 a corresponding body square Cross-sectional.

Refractory cement alone or a dry absorption mixture is used to solidify aqueous nuclear waste made of refractory cement and the like

In order to prevent the set block from drifting apart during the subsequent firing, the added heavy spar is annealed beforehand so that it no longer "splatters" later.

The ones that can be achieved through the new consolidation process Advantages for avoiding dangerous handling before the final firing are best exploited if you have the even and

absorb a suspension of radioactive isotopes. For this purpose, a z. B. made of cheap plastic device according to FIG. 1, in which in a cylindrical container 1 closed at the bottom and open at the top, a funnel 2 with multiple perforated tube 3, which is open at the bottom, is mounted in the middle and, if necessary, centered by some support strips 4 can be held. This filling and filling

Without mechanical tuition taking place distributing the 55 taking device is up to the dashed line 5 with the

Liquid in the receiving mix of the facilities, dry receiving mix filled. Then through

as has already been suggested, proceed in such a way that the funnel is filled with the active liquid until it

the radiating wastewater in the hydraulic on- has evenly distributed throughout the whole mass. as

Mixed intake through the receiving bed with perforated outlet pipes is either purely fireproof

provided funnel is poured and there is 60 cement in the composition after the cement

climbs up below. The tubes remain Taschenbuch, 1954, p. 30, z. E.g .: SiO ₂ 6 to 9%,

if necessary also after setting in the block and Al ₂ O ₃ + Ti O ₂ 46 ″ to 50%, FeO or Fe ₂ O ₃ 0.5 to

together with this the firing process 1.0%, Mn ₂ O ₃ or MnO 0.3%, CaO 37 to 42%,

be subjected. MgO 1.5 to 2.0%, SO ₃ 0.4 ^o / o, or a. such

For the container and filler used in this case, 65 cement with refractory granular aggregates, such as

funnel you can use simple and cheap plastic chamotte, brick chippings or pre-annealed, so not

use the heavy spar that splatters after the hydraulic abrasion. The grain size of the

binding of the filling during the subsequent firing of the aggregate should essentially be less than 5 mm and possibly

ι ι

ι \ j \ j υ

lent lie within the limits between 1.5 and 3 mm. From such a substance takes a cylindrical container of 3 1 content, for example

a) 3.0 kg pure alumina cement (TSZ),

b) 1.8 kg pure TSZ + 1.5 kg chamotte,

c) 1.8 kg pure TSZ + 1.5 kg brick chippings,

d) 1.8 kg pure TSZ + 5.4 kg pre-annealed barite.

After filling and distributing the radioactive liquid without mechanical assistance you set the mixture, which is completed after about 2 days. Now the tied roller body can detached from the mold and then fired. Usually it is more convenient for him cylindrical container and the filling devices to use a cheap plastic and this Let parts burn when the hydraulically set molded body is fired. The roller will With or without a shell, it is heated evenly up to 500 ° C within 5 hours and can then can be quickly brought to the required temperature of around 1000 ° C. The firing temperature to be used depends on the type of cement and the aggregates and can be easily adjusted Determine a preliminary test from mixture to mixture. The excess water evaporates up to 500 ° C. At the firing temperature of z. B. 1100 ° C, the roller is held for about 2 to 4 hours, then slowly to cool off. The burning makes the body largely resistant to leaching and leaching corrosion resistant at all. Compared to other ceramic combustion processes for the disposal of nuclear waste there is the advantage that the components of the mass to be subjected to the solidifying fire do not need to be specially mixed and that the raw material as hydraulically set Block is already completely solid in the drying and kiln.

The fully fired sintered concrete body shows only minor signs after cooling on the surface Traces of the burnt pickup and filling device, As shown in FIG. 2, which is drawn partially transparently, by the slightly wavy lines on the lateral surface 6, the bottom surface 7 and the earlier funnel seat surface 8 is indicated. Fig. 3 shows one Sintered concrete body with a square cross-section, if you use receiving and filling devices that are not used There are plastic, but z. B. made of iron, these can be used in the following hydraulic hardening Fire can be left in the molding without damage. The hopper can also be used shortly before hydraulic hardening.

Claims (5)

PATENT CLAIMS: 1. A method for solidifying aqueous nuclear waste in which the radiating waste water is absorbed by a hydraulic binder and caused to set, characterized in that a refractory cement is first used as the hydraulic binder and then the set block in a manner known per se by a ceramic fire is compacted into a sintered body that is resistant to leaching. 2. The method according to claim 1, characterized in that as a receiving mixture for the formation of the hydraulically setting block of refractory cement with additions of fireclay, Brick chippings or pre-annealed barite is used. 3. The method according to claim 1 or 2, characterized in that the radiant waste water in the hydraulic intake mixture through the filling funnel with perforated discharge pipes is poured in, which remain in the block after setting and together with this the Burning process are subjected. 4. Device for performing the method according to claim 3, characterized by a to be filled with the hydraulically setting intake mixture and with the filling funnel (2) and tubes (3) occupied container (1) made of plastic. 5. According to the method of claims 1 to 3 produced sinking block with a content of radiating isotope waste, consisting of a first hydraulically hardened and then Sintered concrete on the basis of high-alumina cement, compacted by a ceramic fire with surcharges. Documents considered: German Auslegeschrift No. 1 053 686; French Patent No. 1168 251; "Atompraxis", Vol. 2, 1956, pp. 272 to 274; "Atomics", Vol. 8, 1957, pp. 116-120; Ulimann, "Encyclopedia of Technical Chemistry", 1920, p. 225. 1 sheet of drawings © 209 559/443 4.52