Processing NPP Bottoms by Ferrocyanide Precipitation Page: 4 of 9
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WM'02 Conference, February 24-28, 2002, Tucson, AZ
The ozone rate in all three sets was approximately the same and amounted 3 g 03 on 1 g
oxidability, which was equal to 6 g 02/1.
One should point out that in spite Of the fact that data of optical density sampling filtrate after
ozonization are well correlated with specific activity sampling filtrate on Co60, the ozonization is
necessary to finish when specific activity sampling filtrate constant in time, but not optical
density, is achieved. This assumption was confirmed by the following experiment. Total filtrate
after ozonization and ferrocyanide precipitation of three sets (Cs137 - 2 E+5 Bq/1, Co60 - 1500
Bq/l) was subjected to additional ozonization at 60 C with the addition of 0.5 g/l Co(N03)2. The
ozone rate amounted 0,1 g 03 on 1 g oxidability, i.e. 3 % from the total ozone rate for oxidation
of the bottoms. After additional ozonization the specific activity of filtrate was equal to 84 Bq/1.
Thus optical density of filtrate has not changed practically.
Further the influence of accurate filtration on Co60removal from ozonized bottoms were
inverstigated. For this purpose after ozonization of bottoms from the 2-d set and filtration through
the paper filter the additional filtration through the Millipore of filter 0,45 microns was carried
out. The content of 60Co on the Millipore filter and in filtrate after ozonization was determined.
The following results were obtained:
On the Millipore filter - 3,7*10-9 Ci,
In filtrate after ozonization - 1,8*10-9 Ci (1,2*10-8 Ci/l).
Thus, the additional filtration allowed to extract twice more 60Co, than it was remained after
ozonization, and total factor of cleaning was 2500, that is 3,3 times more, than without filtration
through Millipore filter.
Thus, it is necessary to carry out ozonization of NPP bottoms under following conditions:
" Temperature of process - 60 - 80 OC;
" Concentration of Co(N03)2 - 0,5 g/l;
" when specific activity of sampling filtrate on 60Co constant in time is achieved the
process is completed, and separation of deposit formed at ozonization can be carried
out on filters with the pore size < 0,45 microns.
The experiments on ferrocyanide precipitation were carried out at various pH, at various ratios of
reagents , joint and separate separation of a deposit after ozonization and ferrocyanide
precipitation in several stages. At the first stage bottoms after ozonization from the first set was
taken. After performing ferrocyanide precipitation at various pH deposits were filtered. Filtration
was carried out through the double paper filter blue tape . At pH 12,3 Cs is not precipitated
practically, and in a range pH 9 - 10,8 the factors of cleaning on Cs 130 - 200 were obtained. The
solutions K4Fe(CN)6 H Ni(N03)2 were brought in stoichiometry ration to obtain 1 g/l of
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Savkin, A. E.; T., Slastennikov Y. & G., Sinyakin O. Processing NPP Bottoms by Ferrocyanide Precipitation, article, February 25, 2002; Tucson, Arizona. (digital.library.unt.edu/ark:/67531/metadc785551/m1/4/: accessed September 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.