The method of fixation of radioactive waste

 

(57) Abstract:

The invention relates to nuclear energy, in particular to methods of radioactive waste management (RW), located in the basins of storage in the form of aqueous solutions and suspensions of sediment. Sediments contain radionuclides by several orders of magnitude greater than the aqueous phase of the basin-store. Sediments are characterized by high mobility, can easily vspuchivatsya, to flow and to be extruded at the conservation pools of storage by filling. The main technical challenge in conservation pools stores is reliable fixation sediment RAO on the bottom of the reservoir by filling them without mixing with vodolazam not less than 2 slag, which is then ground to a specific surface 4000-6000 cm2/, the Height of the slag backfill shall be not less than 2.5 cm, and the speed of filling of 0.125-0,375 m2/H. This method allows you to get a secure fit RAO on the bottom of the pool store, their subsequent curing and robust composite, ensuring their safe disposal. 1 C.p. f-crystals, 2 tab.

The invention relates to the field of nuclear energy, in particular to Stadnyk solutions and suspensions of sediment.

Sediments contain radionuclides by several orders of magnitude greater than the aqueous phase of the basin-store. Consisting mainly of colloidal phases hydroxides of Fe+3and Al+3sediments are characterized by high mobility, can easily vspuchivatsya, to flow and to be extruded at the conservation pools of storage by filling. The output of bottom sediments on the water or on the shore, due to the mixing or extrusion, is dangerous as a source of possible emergency windscreen separation of radionuclides, because the power (height) of bottom sediments increases as a result of their displacement during filling of waters of the pool store.

Known technology fixation sediment RAO at the conservation pool storage by filling rocky soil with the use of hollow concrete blocks /1/.

The disadvantages of this method include the lack of binding properties of the backfill material, which does not allow to reliably fix RAO on the bottom of the pool store.

Also known a technology of filling the waters of the basin-store by horizontal slipped on easily rock soil from the shore to the centre of the pond /2/. The main disadvantage of this method t is I.

The closest technical solution to the present invention is a method of curing waste containing radioactive isotopes, by mixing with steel granulated slag with vodolazam respect of 0.2 - 0.6 with a specific surface area binder 2800 - 4000 cm2/g /3/ prototype.

The disadvantages of the method prototype should include mandatory mixing of the slag after filling in waste and solidification at low vodolazam respect of 0.2 to 0.6, which is not possible in the case of sediment RAO to ensure a secure fit on the bottom of the pool store.

In this regard, the main technical challenge in the conservation of basin-RW repositories is a reliable fixation of sediment RAO at the bottom by filling them without mixing metallurgical slag, followed by curing and robust composite, ensuring safe disposal of radioactive waste.

This new technical result is achieved in that in the method of fixation of radioactive waste by filling and curing of metallurgical slag backfill produced without mixing with vodolazam not less than 2 slag, which is then ground to a specific item is delivered 0,125 - 0,375 m2/PM

A significant difference in the specific weights of metallurgical slag (d=a 3.2-3.4 g/cm3and sediment RAO (d~1,2-1,3 g/cm3) causes the penetration of the slag particles in the depth of the colloidal phase sediment, causing lifting and squeezing the last filling.

The degree of extrusion of bottom sediments, which is defined as the ratio of the number of bottom sediments above the slag backfill the remaining beneath it depends on the speed of filling slag (m2/h), height (cm) and should not exceed 0.1.

For metallurgical slag with a specific surface area of 4000 - 6000 cm2/g degree of extrusion sediment RAO at a speed of slag backfill 0,125 - 0,375 m2/h does not exceed 0.1. The increase in the rate of slag backfill up to 0.45 m2/h causing the rise of sediment RAO and increase the extent of their bump to 0.12 to 0.15 for both primary and sour metallurgical slag.

At the height of the slag backfill less than 2.5 cm (specific surface area of from 4000 to 6500 cm2/g), as and when the specific surface area of 3500 cm2/h (the height of the backfill 2.5 cm) effect of solidification absent in both types of toxins under the water phase at a depth of 1 m during the year. Vaem. Due to the fact that over the bottom sediments RAO is always a layer of the aqueous phase depth of 1 m, vodovorote ratio is at least 2. The strength of the monoliths when you commit sediment RAO slag backfill exceeds one year 270 kgf/cm2. The increase in specific surface metallurgical slag up to 6500 cm2/g does not change the parameters of strength, but is not economically advisable.

Examples of implementation

Example 1. Metallurgical slag (acidic or basic) is crushed to obtain a specific surface area of 3500 - 6500 cm2/'clock In the aqueous phase pool storage depth of 1 m is poured out without mixing the slag with a specific surface area of 3500, 4000, 6000 and 6500 cm2/g, creating a height of backfill 1,0; 2,5 and 30 cm and maintained during the year. As the aqueous phase of the basin-store use distilled water (similar rainfall) or salt solution containing NaNO3, PA2SO4, Na2Ac, NaCl, Mq+2Ca+2at pH of 8.9-9.0 and the amount of salt 80 g/L.

The test results of samples of the slag backfill strength after one year of exposure in the aqueous phase are presented in table. 1.

From the data presented in table. 1, it follows that when the height of the slag backfill less than 2.5 and not harden. Similar results in reduction of the specific surface of the slag from 4000 to 3500 cm2/g at a height of backfill 2,5 see

The increase in the specific surface of the slag from 6000 to 6500 cm2/g does not change the parameters of strength, but uneconomical. Metallurgical slag with a specific surface area of 4000 - 6000 cm2/g hardened to a depth of 1 m at vodolazam not less than 2 in water and water-salt solutions at the height of the backfill is not less than 2.5 cm, forming one year composite, the strength of which exceeds 300 kgf/cm2.

Example 2. Metallurgical slag (acidic or basic) is crushed to obtain a specific surface area of 4000 - 6000 cm2/year In the aqueous phase of the basin-store, containing at a depth of 1 m sediment RAO, pour out without mixing the slag (specific surface area of 4000, 6000 cm2/g) with a speed of filling 0,125; 0,375; 0.45 m2/h, creating a height of backfill 2,5; 6; 15; 30; 34 cm and fixing the degree of extrusion of sediment.

As the simulator sediment RAO basin-store use a suspension of hydroxides of iron and aluminium, taken in the ratio of Fe+3:Al+3=1:1 with a concentration of 13.3 g/l in a solution of NaNO3(70 g/l) at pH 9-10. The results of the COI is dstanley in table. 2.

From the data table. 2 it follows that when the speed of filling 0,125 - 0,375 m2/h for metallurgical slag with a specific surface area of 4000 - 6000 cm2/g degree of extrusion sediment RAO does not exceed 0.1 at the height of the backfill is not less than 2.5 see an increase in the speed of the slag backfill up to 0.45 m2/h causing the rise of sediment RAO and increase the extent of their bump to 0.12 to 0.15 for both primary and sour metallurgical slag.

Metallurgical slag acidic and basic with a specific surface area of 4000 - 6000 cm2/g covered without stirring speed 0,125 - 0,375 m2/h, and the height of the slag backfill of at least 2.5 cm begin to solidify when vodolazam more 2 through 140 - 110 and 12 days, respectively. A year later the strength of the slag monoliths commit sediment RAO is more than 270 kgf/cm2.

Thus, the use of the proposed method will allow you to get a secure fit of the bottom sediments of radioactive wastes resulting from the curing that will ensure the safety of their burial in water basins stores.

Sources of information

1. Y. C. Glagoleva, E., zekun and other Strategy for radioactive waste is alexahin, C. A. Egorov. Retrospective recovery of morphometric parameters oz. Karachay using geographic information systems. The issues of radiation safety, N 4, 1996, S. 60 - 66, the Magazine "Mayak", the Ministry of atomic energy.

3. Auth. testimony N 880149, publ. 30.04.82. Newsletter # 16 (prototype).

1. The method of fixation of radioactive waste by filling and curing of metallurgical slag, characterized in that the filling is produced without mixing with vodolazam not less than 2, and metallurgical slag is then ground to a specific surface area of 4000 - 6000 cm2/g, and the height of the slag backfill shall be not less than 2.5 cm, and the speed of filling of 0.125 - 0,375 m2/PM

2. The method according to p. 1, characterized in that used as the acidic and basic metallurgical slag, with astringent properties in water, aqueous salt solutions and suspensions.

 

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