CS241724B1 - Sorbent for radioactive ruthenium catching from radioactive gas waste - Google Patents

Abstract

The solution is to prepare the impregnated of sorbent removing radioruthenium from gaseous radioactive waste would be easily convertible into a glass form long-term storage is safe and economical. Quartz sand or crushed glass The frit is the carrier of the active ingredient of the sorbent iron oxide or ruthenium oxide. The subject of the invention is impregnated sorbent, having a composition of 0.2 to 2% iron oxide or ruthenium and whose preparation it consists either in mixing the carriers themselves with a solution of ferric nitrate at temperature 20 ° C, drying and annealing at 550 ° C mixtures, or in mixing the carriers themselves by vigorous shaking with powdered oxide ruthenium at 20 ° C. Impregnated in this way sorbents can be easily converted to form glass and can remove 106RuO4 vapors from waste gas from vitrification with efficiency of 3% ment. Impregnated sorbents can also be used for removing radioruthenium from gases generated reprocessing spent nuclear fuel and from the combustion gases radioactive waste.

Description

The present invention relates to a sorbent for trapping radioruthenium from gaseous radioactive waste.

Gases produced during calcination and vitrification of high-level waste containing radionuclide ^1UB Ru as vapor ^{LT) B} RuO4 waste with a half of 1.02. This radioruthenium in the form of ¹⁰⁵ RuO4 vapor has so far been removed from the waste gas by sorption on inorganic sorbents. As the inorganic sorbent, silica gel, iron oxide, alumina, aluminosilicates and others are used. Some inorganic sorbents impregnated with ferric oxide achieve higher sorption efficiencies for vapors ^{1 (IB} RuO4 than non-impregnated) (see, for example, Control of Semivolatile Radionuclides in Nuclear Facilitles, Tech. Rep. Ser., No. 220, IAEA, Vienna 1982) .

The disadvantage of these sorbents is their difficult disposal after saturation, or it is necessary to store them without treatment in the radioactive waste storage, which is uneconomical and dangerous.

These disadvantages are overcome by the sorbent for capturing radioactive ruthenium from the gaseous radioactive waste according to the invention, which is based on the fact that its active ingredient is iron oxide or ruthenium dioxide, the carrier of the active ingredient sorbent is silica sand having a grain size of 0.3 to 2.0 millimeters or glass frit of grain size 0.4 to 2.0 mm. These carriers are glass raw materials and the sorbent used can thus be easily converted into glass, which is more economical and much safer in terms of storage. The sorbent contains 98.0 to 99.8 wt. % carrier and 0.2 to 2.0 wt. iron oxide or ruthenium dioxide. It is produced by mixing the carriers with a solution of ferric nitrate at 20 ° C, drying the resulting mixture and calcining at 550 ° C, or mixing the carriers with vigorous shaking with RuO 2 powder at 20 ° C.

The higher effect of the invention is due to the fact that the sorbent used can be disposed of safely and cheaper. The novel effect of the invention is that the sorbent reduces the concentration of radioactive ruthenium from radioactive gaseous waste by three orders of magnitude at a relatively low temperature of 50 ° C.

The preparation and use of the sorbent is evident from the following examples:

Example 1 g quartz sand of 0.3 mm grain was mixed with a solution of ferric nitrate [1.82 g Fe (NO3) 3.9H2O in 20 ml distilled water] at 20 ° C. After stirring, the mixture was evaporated to dryness under infra-lamp, then calcined for 1 hour at 550 ° C to convert Fe (NO 3) 3 to Fe 2 O 3. The concentration of iron in the solution was such that the impregnated quartz sand formed contained 1% (w / w). Or, 28 grams of 0.3 mm silica sand was mixed with 100 mg of commercial powdered ruthenium dioxide, and the mixture was shaken vigorously on a shaker for 15 minutes at 20 ° C, after which time both materials were thoroughly mixed. The RuO2 in the impregnated sorbent was 0.35 percent (wt.

Example 2

A solution of ferric nitrate [1.82 grams of Fe (NO3) 3.9H2O in 20 mL of distilled water] was added to 28 g of 2.0 mm silica sand. The mixture was stirred at 20 ° C and then evaporated to dryness under infrared lamp. Evaporation was followed by calcination at 550 ° C for 1 hour to allow Fe (NO 3) 3 to convert to Fe 2 O 3. The concentration of iron in the solution was such that the impregnated quartz sand formed contained 1% Fe ₂ O ₃ (w / w). Alternatively, 28 g of 0.8 mm silica sand was mixed with 100 mg of commercial powdered ruthenium dioxide. The resulting mixture was shaken vigorously on a shaker for 15 minutes at 20 ° C. After this time both materials were perfectly mixed, the RuO2 content in the impregnated sorbent was 0.35% (w / w).

Example 3 g of 0.4 mm glass frit containing 46% PbO, 35% SiO2, 4% K2O and 15% B2O3 was mixed with a solution of ferric nitrate [1.82 g Fe (NO3, 3.9H2O in 20 ml distilled water) at a temperature of After stirring, the mixture was evaporated to dryness under infra-lamp, then calcined at 550 ° C for 1 hour to bring Fe (NO 3) to Fe 2 O 3. The solution concentration was such that the impregnated glass frit formed contained 1% Fe 2 O 3 (wt. Or 36 g of glass frit of 0.4 mm grain size was mixed with commercial powdered ruthenium dioxide, and the resulting mixture was shaken vigorously on a shaker for 15 minutes at 20 [deg.] C. After this time both materials were mixed perfectly, RuO2 content in the impregnated sorbent was 0.28% (w / w).

Example 4

To 36 g of a 2.0 mm glass frit of the same composition as in Example 3 was added a ferric nitrate solution [1.82 g Fe (NO3) 3].

. 9H2Q in 20 mL distilled water]. The mixture was stirred at 20 ° C and then evaporated to dryness under infra-lamp. Evaporation was followed by annealing at 550 ° C for 1 hour to bring Fe (NO 3) 3 to Fe 2 O 3. The iron concentration in the solution was such that the impregnated glass frit contained 1% Fe 2 O 3 or 36 g of glass frit 0.6 mm grain size was mixed with 100 mg of commercial ruthenium dioxide powder and vigorously shaken on a shaker for 15 minutes at 20 DEG C. After this time both materials were thoroughly mixed, the content of RuO2 in the impregnated sorbent was 0.28 % (w / w).

Example 5

The impregnated sorbent [28 g quartz sand grain 0.3-0.8 mm or 36 g glass frit grain 0.4-0.6 mm] was contacted in the box with laboratory vitrification waste gas containing 0.5 μ% / \ RuOá (labeled ^1UB Ru). At a gas flow rate of 2.35 cm / s, a temperature of 50 ° C, more than 99.9% RuCk was removed from the gas. In contrast, when contacting the laboratory vitrification waste gas with non-impregnated sorbents under otherwise identical conditions, the removal of RuCU from the gas was only 99.0 to 99.5%.

It follows from Example 5 that the sorbents prepared according to the invention reduced the concentration of RuO4 vapor in the off-gas from the vitrification by three orders of magnitude, while not impregnated by only two orders of magnitude. On ferric silica impregnated silica, a temperature of 200 ° C or higher was required to achieve a 3-order reduction in the RuO4 vapor concentration in the gas of 3 orders [see A. Donato, W. Bocola, Energia Nucleare 18 (1971) 353]. it is also possible to remove radioruthenium from the gas in the form of an aerosol.

Claims (3)

SUBJECT A sorbent for the capture of radioactive ruthenium from gaseous radioactive waste impregnated with iron oxide or ruthenium dioxide, characterized in that it is composed of 98 to 99.8% by weight of the composition. an active ingredient carrier which is quartz sand having a grain size of 0.2 to 2 mm, or a glass frit having a grain size of 0.4 to 2 mm, and 0.2 to 2 wt. iron oxide or ruthenium dioxide. 2. The sorbent of claim 1, wherein the glass frit contains 46 wt. PbO, 35% by weight of S1O2, 4% by weight of K2O and 15% by weight of B2O3. 3. A process according to claim 1, characterized in that the carriers are mixed with a ferric nitrite solution at a temperature of 20 DEG C., the mixture is annealed at 550 DEG C., or the carriers are mixed by vigorous shaking with RuO2 powder at 20 DEG C. wherein the amount by weight of the RuO2 carrier and the concentration of Fe (NO3) 3 is such that the sorbent composition corresponds to that referred to in point 1.