RU2004608C1 - Method for copper alloy with radionuclides contamination metal waste utilizing - Google Patents

Description

After overheating and overheating of the metal to 1150-1400 ° C, the resulting slag was removed and the metal was poured into the molds or a new portion of flux was added, kept for 20 minutes and after the slag was removed, it was also poured into the mold.

Samples of metal and slag were analyzed using a gamma spectrometer based on the Noki analyzer with a DGDK-80B detection unit. The results obtained during the experimental swimming trunks are shown in tables 1-4.

From the results presented in Table 2, it can be seen that the cobalt - 60 cd increases from 2 with a flux amount of 1% to 44 with a flux amount of 19%. Already small amounts of copper oxides (10%) added to polymetaphosphates lead to a marked increase in the decontamination efficiency. It was found that the maximum effect is observed with the following ratios of flux components, wt.%:

Polymetaphosphates

alkali metals 30-70

Copper oxides 30-70

If it is necessary to obtain Kd according to Co60 above the values indicated in Table 2, it is necessary to remove the formed slag and add a new portion of flux, and Kd from cobalt-60 will increase significantly (see Table 3).

The results shown in Table 2 show that when the flux is added twice, the total consumption of reagents decreases and the effect increases many times.

Pilot tests have shown that one of the conditions for obtaining high values of Cd during remelting in heavy-duty furnaces with multi-cycle processing of the melt by flux is to add the first portion of the flux

uniformly in small portions throughout the entire metal smelting process.

The data in Table 3 show that the decontamination efficiency when adding flux at the beginning of smelting and re-adding it after removing the resulting slag is equivalent to adding twice the amount at the beginning of smelting. With uniform addition of flux in small parts throughout the entire melting process and its repeated addition after removal of the resulting slag, the expected effect was obtained.

One of the conditions for obtaining high Kd is the absence of metal deoxidation in the crucible of the furnace, since this will result in the restoration of part of the radionuclides from the residues of slag adhered to the walls of the furnace.

From the results of the melts presented in table 4, it is seen that the remelting of waste from copper and copper-nickel alloys with a flux known in metallurgy does not allow Co-60 Kd to reach more than 5.4, while remelting them according to the proposed method allows obtaining Co-60 CDs of 100 or more up to 1000. With a normalized value of the residual radioactive contamination of the ingot r-eq, rad / kg (20 μR / h), the initial specific radioactivity of the metal can be r-eq.rad / kg (dose rate 2-20 mR / h), which does not exceed the values of real pollution in situ th metal sample. In this case, Ce-144, Co-90, Y-90, Cs-137, Fe-59, Zn-65, all rare-earth and transuranic elements are almost completely removed from the metal. The phosphorus content in the resulting ingot does not exceed 0.007%, which is significantly lower than the permissible values.

Table 1

Coefficient of deactivation of Cd from cobalt-60 during remelting of waste from MNZhMts-5-1-1 with the addition of a mixture of alkali metal polymetaphosphates and oxides as a flux

copper in a ratio of 1: 1

table 2

Co-60 deactivation coefficients obtained from the remelting of radioactive waste from MNZhMts-5-1-1 with the double addition of flux from a mixture of 50% alkali metal polymetaphosphates and 50% copper oxides.

Table 3

The results of remelting waste from a copper-nickel alloy MNZHMts-5-1-1 when a mixture of alkali metal polymetaphosphates and copper oxide is added as a flux in a ratio of 1: 1

The amount of flux, May. %

Flux Addition Conditions

4.0, 0-2.0

, 0-2.0

One-time addition of flux at the beginning of melting. Addition of a portion of flux at the beginning of melting (2%) and repeated addition after complete melting of the metal and removal of slag. Uniform addition of a portion of flux throughout the entire smelting (2%) and re-addition after complete melting of the metal and removal of slag.

Table 4

Cobalt-60 deactivation coefficients of waste from copper and copper-nickel alloys during remelting using various alkali metal polymetaphosphates or alloys with copper oxides as fluxes taken in the ratio 1.1

Flux used in metallurgy

Coefficient of cleaning for Co-60

2.9-3.2 3.6

109

Claims (1)

1. A METHOD FOR DISPOSAL OF METAL WASTE FROM ALLOYS ON THE BASIS CONTAMINATED BY RADIONUCLIDES, consisting in cutting, monitoring of radioactive contamination by comparing the activity of a metal with the activity of an extended source of radiation-226 in equilibrium with daughter products by measuring the radiation exposure rate, gamma induction furnace in a controlled area in the air with the addition of refining fluxes having a liquidus temperature below the melting point of metal waste, pointing and removed and slag and metal in a casting mold to obtain ingots. 2, The method according to claim 1, characterized in that the radioactive contamination of the waste before melting is controlled by measuring the dose rate P close to the surface of the container with dimensions of at least 0.6 0.6 0.6 m and a metal loading density of at least 1 , 0 t / m, which is not dol 5 0 5 should exceed the value determined from the formula, mR / h: P - 0.02 grasch n , 2 / fi / Ko I - I where I 1 - p; n is the number of radionuclides present in the composition of the pollution: fi is the fraction of the 1st radionuclide in total activity; K0 | - the coefficient of metal purification from the 1st radionuclide in the melting process. 3. The method according to claim 1, characterized in that the radioactive contamination of the ingots is controlled by measuring the exposure dose rate of gamma radiation on the surface of each ingot and for an ingot whose minimum linear size is greater than 0.3 m, this value should not exceed 0.02 mR / h 4. The method according to claim 1, characterized in that alkali metal polymetaphosphates and mixtures of alkali metal polymetaphosphates and copper oxides are used as refining fluxes during the smelting process.