Abstract
{sup 60}Co is produced as an activation product and is present in the low-level aqueous radioactive waste released from the La Hague plant. At present, the concentration in the sea (non filtered at 0.45 {mu}m) at the Goury site are close to or even below, the detection limit: 0.2 mBq.l{sup -1}. The {sup 60}Co speciation depends on the type of effluent considered: in the effluent A ('active'), the cobalt is in the form of a stable trivalent complex; in the effluent V (to be checked), the cobalt is in majority (50% of the activity release) in the form of particles (>0.45 {mu}m), and then in the form of two soluble species: ionic divalent (Co{sup 2+}) and some stable complexes. The evolution of the reprocessing techniques used does not affect the speciation. So, since the nuclear reprocessing plant started at the La Hague plant in 1966, the chemical species discharged in the sea shows time variation related to the evolution of the type of effluent discharged. Thus, since 1994, the particles of cobalt are the main species discharged in the Channel (the V effluents represent more than 85% of the total {sup 60}Co activity released). The effect of instantaneous dilution into
More>>
Citation Formats
Gaudaire, J M.
Study of the {sup 60}Co speciation in the aqueous radioactive waste of the la Hague nuclear reprocessing plant; environmental behaviour after discharges in the waters of the channel; Etude de la speciation du {sup 60}Co dans les effluents de l'usine de retraitement de combustibles irradies de la Hague; devenir apres rejet dans les eaux de la Manche.
France: N. p.,
1999.
Web.
Gaudaire, J M.
Study of the {sup 60}Co speciation in the aqueous radioactive waste of the la Hague nuclear reprocessing plant; environmental behaviour after discharges in the waters of the channel; Etude de la speciation du {sup 60}Co dans les effluents de l'usine de retraitement de combustibles irradies de la Hague; devenir apres rejet dans les eaux de la Manche.
France.
Gaudaire, J M.
1999.
"Study of the {sup 60}Co speciation in the aqueous radioactive waste of the la Hague nuclear reprocessing plant; environmental behaviour after discharges in the waters of the channel; Etude de la speciation du {sup 60}Co dans les effluents de l'usine de retraitement de combustibles irradies de la Hague; devenir apres rejet dans les eaux de la Manche."
France.
@misc{etde_20089062,
title = {Study of the {sup 60}Co speciation in the aqueous radioactive waste of the la Hague nuclear reprocessing plant; environmental behaviour after discharges in the waters of the channel; Etude de la speciation du {sup 60}Co dans les effluents de l'usine de retraitement de combustibles irradies de la Hague; devenir apres rejet dans les eaux de la Manche}
author = {Gaudaire, J M}
abstractNote = {{sup 60}Co is produced as an activation product and is present in the low-level aqueous radioactive waste released from the La Hague plant. At present, the concentration in the sea (non filtered at 0.45 {mu}m) at the Goury site are close to or even below, the detection limit: 0.2 mBq.l{sup -1}. The {sup 60}Co speciation depends on the type of effluent considered: in the effluent A ('active'), the cobalt is in the form of a stable trivalent complex; in the effluent V (to be checked), the cobalt is in majority (50% of the activity release) in the form of particles (>0.45 {mu}m), and then in the form of two soluble species: ionic divalent (Co{sup 2+}) and some stable complexes. The evolution of the reprocessing techniques used does not affect the speciation. So, since the nuclear reprocessing plant started at the La Hague plant in 1966, the chemical species discharged in the sea shows time variation related to the evolution of the type of effluent discharged. Thus, since 1994, the particles of cobalt are the main species discharged in the Channel (the V effluents represent more than 85% of the total {sup 60}Co activity released). The effect of instantaneous dilution into the marine conditions involving a variation of pH, oxido-reduction, ionic strength, a gradient of salinity, does not interfere with the evolution of the chemical species discharged. Nevertheless, during the discharge of the V effluent, the main constituents of the sea water (Mg{sup 2+} and Ca{sup 2+}) go through a precipitation. This comes with the coprecipitation of the ion Co{sup 2+} and with the particles of cobalt (complexes are not affected), and it can be responsible for an increase in the concentration in the particles. The chemical behaviour of the cobalt in the Channel is different from those of conservative element such as antimony. The ionic cobalt and the particles have a small dispersion in the water (cobalt has a very high particle/dissolved distribution factor, it is a non-conservative radionuclide). This sedimentary stock can involve a second source of activity. The power of complexation of the Channel's filtered water is very small (contrary to the rivers like the Seine which has a lot of organic material). Because of the weak activity of the dissolved phase and the weak percentage of complexes, insufficient evidence (even if the reactivity between the complexes and the sedimentary particles are small) has, as yet, been obtained to confirm that the presence of stable complex significantly increases the mobility and dispersion of {sup 60}Co arising from the discharge. However, with a strong dilution, 99% of complexes disappear (conversion of trivalent complex to the divalent ionic form which is more particle-reactive form) between 9 and 44 months. (author)}
place = {France}
year = {1999}
month = {Jul}
}
title = {Study of the {sup 60}Co speciation in the aqueous radioactive waste of the la Hague nuclear reprocessing plant; environmental behaviour after discharges in the waters of the channel; Etude de la speciation du {sup 60}Co dans les effluents de l'usine de retraitement de combustibles irradies de la Hague; devenir apres rejet dans les eaux de la Manche}
author = {Gaudaire, J M}
abstractNote = {{sup 60}Co is produced as an activation product and is present in the low-level aqueous radioactive waste released from the La Hague plant. At present, the concentration in the sea (non filtered at 0.45 {mu}m) at the Goury site are close to or even below, the detection limit: 0.2 mBq.l{sup -1}. The {sup 60}Co speciation depends on the type of effluent considered: in the effluent A ('active'), the cobalt is in the form of a stable trivalent complex; in the effluent V (to be checked), the cobalt is in majority (50% of the activity release) in the form of particles (>0.45 {mu}m), and then in the form of two soluble species: ionic divalent (Co{sup 2+}) and some stable complexes. The evolution of the reprocessing techniques used does not affect the speciation. So, since the nuclear reprocessing plant started at the La Hague plant in 1966, the chemical species discharged in the sea shows time variation related to the evolution of the type of effluent discharged. Thus, since 1994, the particles of cobalt are the main species discharged in the Channel (the V effluents represent more than 85% of the total {sup 60}Co activity released). The effect of instantaneous dilution into the marine conditions involving a variation of pH, oxido-reduction, ionic strength, a gradient of salinity, does not interfere with the evolution of the chemical species discharged. Nevertheless, during the discharge of the V effluent, the main constituents of the sea water (Mg{sup 2+} and Ca{sup 2+}) go through a precipitation. This comes with the coprecipitation of the ion Co{sup 2+} and with the particles of cobalt (complexes are not affected), and it can be responsible for an increase in the concentration in the particles. The chemical behaviour of the cobalt in the Channel is different from those of conservative element such as antimony. The ionic cobalt and the particles have a small dispersion in the water (cobalt has a very high particle/dissolved distribution factor, it is a non-conservative radionuclide). This sedimentary stock can involve a second source of activity. The power of complexation of the Channel's filtered water is very small (contrary to the rivers like the Seine which has a lot of organic material). Because of the weak activity of the dissolved phase and the weak percentage of complexes, insufficient evidence (even if the reactivity between the complexes and the sedimentary particles are small) has, as yet, been obtained to confirm that the presence of stable complex significantly increases the mobility and dispersion of {sup 60}Co arising from the discharge. However, with a strong dilution, 99% of complexes disappear (conversion of trivalent complex to the divalent ionic form which is more particle-reactive form) between 9 and 44 months. (author)}
place = {France}
year = {1999}
month = {Jul}
}