Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

Крот, Н. Н.; Shilov, V. P.; Bessonov, A. A.; Budantseva, N. A.; Чарушникова, И. А.; Перминов, В. П.; Astafurova, L. N.

doi:10.2172/353259

Cited by 18 publications

(55 citation statements)

References 14 publications

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“…The IPClRAS scientists observed the relative instability of dissolved Pu(V) in coprecipitation reactions reported by Krot et al (1996), in oxidationlreduction studies reported by Shilov et al (1996), and in Pu(V) salt solubility tests reported by Peretrukhin et al (1996). Each report suggested that the instability of Pu(V), shown by its propensity to convert to Pu(IV) hydrous oxide of low solubility, was caused by its disproportionation to Pu(IV) and PU(v1).…”

Section: Plutonium(v) Stability and Propertjes In Alkalimentioning

confidence: 93%

Liaison activities with the Institute of Physical Chemistry, Russian Academy of Sciences: FY 1997

Delegard¹,

Elovich²

1997

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Section: Plutonium(v) Stability and Propertjes In Alkalimentioning

confidence: 93%

Liaison activities with the Institute of Physical Chemistry, Russian Academy of Sciences: FY 1997

Delegard¹,

Elovich²

1997

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“…Conditions under which the Precipitates formed, determined by Krot et al (1996), gave moderate decontamination from neptunium and generally excellent decontamination from plutonium. As shown in the previous section, partial coprecipitation of technetium can be attained if the reductant hydrazine is used.…”

Section: Coprecipitation Of Cesium By the Methods Of Appearing Reagentsmentioning

confidence: 99%

“…Maximum DFs are observed for NaJJO,. The experimental procedure to produce the precipitates was similar to that described in previous sections and was based on the studies of Krot et al (1996). The coprecipitation test data are presented in Table 4.7.…”

Section: Coprecipitation Of Strontium By the Methods Of Appearing Reagmentioning

confidence: 99%

Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

Peretrukhin¹,

Silin²,

Тананаев³

et al. 1997

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SummaryEffective decontamination of alkaline solutions and Hanford Site tank waste simulants from technetium has been accomplished by reductive coprecipitation with iron(II1) hydroxide. Addition of 1 M (NH4),Fe(S04), to 0.5 to 4.0 M NaOH to a final concentration of 0.1 to 0.15 M coprecipitates more than 99% of the technetium from 0.5 to 1.0 &j NaOH and 98 to 96% from 2.0 to 4.0 M NaOH. Similar results were obtained by reduction of Tc(VII) with 0.1 to 0.15 &j hydrazine and subsequent addition of FeCI, to a final concentration of 0.15 M. Inclusion of four complex-fonning agents rO.01 &j phosphate, 0.1 M EDTA (ethylenediaminetetraacetate), 0.03 M citrate, and 0.1 M glycolate (HOCH,CO;)] to the alkaline solution decreases technetium coprecipitation with iron hydroxide to 85% under otherwise similar conditions. Inclusion of 0.04 M NqCrO, drastically decreases reductive coprecipitation of Tc(VII) in 0.5 to 4.0 M NaOH. Iron(I1) salt, added to a 0.07 M excess over that of chromate, completely reduces chromate and provides greater than 99% coprecipitation of technetium with product iron(II1) and chromium(II1) hydroxides. Technetium(VI1) reduction by hydrazine is slow in the presence of chromate in alkaline solution, and technetium coprecipitation is incomplete in these conditions. Decontamination of an alkaline Hanford Site tank waste simulant, containing 0.04 &j chromate and eleven salts and complex-forming agents, by adding 1 M iron(I1) salt solution was studied.Coprecipitation of 15 to 28% of the technetium and more than 99% of the plutonium occurred in the Fe/Cr(III) hydroxide precipitate produced by adding 0.05 to 0.10 _M iron@). Chromate reduction was incomplete. About 75% of the technetium was coprecipitated, and the chromate was completely reduced, after adding 0.2 _M iron@) salt.Technetium(VI1) capture from 0.5 to 4.0 M NaOH was insignificant or incomplete on coprecipitation carriers Pe(OH),, Cr(OH),, Mn(OH),, Co(OH),, Co(OH),J obtained by the Method of Appearing Reagents under conditions providing complete capture of Np(V) and Pu(V1). Under the same conditions, cesium-137 capture is insignificant and strontium-90 capture is incomplete with these metal hydroxide carriers. Sodium diuranate coprecipitation from 0.5 to 4 M NaOH removed about 15 to 60? -of the technetium; sodium uranate coprecipitation removed 98 to 99% of the 90Sr, and 1 to 12% of the l3'CS.Reductive sorption of Tc(VI1) on metals (Zn, Cry Sn, and two Pb alloys) from 0.5 to 4 M NaOH and from alkaline waste simulant provided poor decontamination of these solutions. In contrast, greater than 98% of the plutonium(V1) was sorbed on chromium from 0.5 M NaOH at a surface area to volume ratio of 1.6 cm-'.

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“…Plutonium separations subsequently made in both countries by the PUREX process left proportionately less nonradioactive salt in the radioactive wastes. Recent studies have shown that coprecipitation by the Method of Appearing Reagents (MAR) purifies alkaline waste solutions of transuranium elements and technetium with decontamination factors (DFs) of 100 to 1000 (Krot et al 1996;Krot and Charushnikova 1997;Bessonov et al 1997;Peretrukhin et al 1997). In contrast to the BiP04, LaF3, or NaU02(CH3C00)3 coprecipitation methods for removing plutonium from nitric acid, coprecipitation of transuranic elements and technetium (IV,V) from NaOH solution on metal hydroxides or on uranate salts does not require salt removal.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to the BiP04, LaF3, or NaU02(CH3C00)3 coprecipitation methods for removing plutonium from nitric acid, coprecipitation of transuranic elements and technetium (IV,V) from NaOH solution on metal hydroxides or on uranate salts does not require salt removal. In addition, decontamination of alkaline solutions from transuranic elements requires introduction of only small concentrations (0.001 to 0.01 M) of metal hydroxide carrier (Krot et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Purification of alkaline solutions and wastes from actinides and technetium by coprecipitation with some carriers using the method of appearing reagents: Final Report

Peretrukhin¹,

Silin²,

Kareta³

et al. 1998

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The coprecipitation of transuranium elements and technetium from alkaline solutions and from simulants of Hanford Site tank wastes has been studied in reducing and oxidizing conditions on uranium(IV,vT) hydroxocompounds, tetraakylammonium perrhenate and perchlorate, and on hydroxides of Fe(m), Co(III), Mn(II), and C r o using the Method of Appearing Reagents (MAR). Coprecipitations in alkaline solution have been shown to give high decontamination factors (DF) at low content of carrier and in the presence of high salt concentrations.Uranium(IV) hydroxide in concentrations higher than 3~1 0 -~ M coprecipitates Pu and Cm in any oxidation state from 0.2 to 4 M NaOH with DFs of 110 to lo00 and Np and Tc with DFs of 51 to 176. UraniumCvI), introduced as a sodium uranate precipitate or the soluble peroxocomplex salt NaUO2(02)3, can be partially reduced in 0.2 to 2 M NaOH by hydrazine to U30~.nH20 in the presence of (1 to 5 )~1 0 -~ M Tc(VII). The Tc(VlI) is first reduced to Tc(IV). The product U308.nH20, at 0.012 to 0.05 M uranium, coprecipitates Np, Pu, Cm, and Tc in any oxidation state with DFs greater than 100 from 0.2 to 1.5 M NaOH. Increasing alkali concentration to 4 M NaOH decreases the DFs slightly for TRU and drastically for Tc. Coprecipitation under the same conditions from simulated tank waste containing 3.2 M NaOH, 0.04 M C1-05-and 11 complex-forming salts yields the following DFs: Np-12, Pu-27, Cm-35, Tc-3. The decrease of DFs in the waste simulant is associated with complex formation and with inhibition of Np and Tc coprecipitation by the Cr(m) hydroxide that is formed before Np(IV) and Tc(IV). Coprecipitated Tc may be effectively leached from U30p-nH20 by oxidation of Tc(IV) to Tc(VII) by use of dilute H202 or by NaOH solution and air bubbling. Under these same conditions, more than 99% of the Pu is retained in the solid phase. iii

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Investigation on the co-precipitation of transuranium elements from alkaline solutions by the method of appearing reagents

Cited by 18 publications

References 14 publications

Liaison activities with the Institute of Physical Chemistry, Russian Academy of Sciences: FY 1997

Liaison activities with the Institute of Physical Chemistry, Russian Academy of Sciences: FY 1997

Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

Purification of alkaline solutions and wastes from actinides and technetium by coprecipitation with some carriers using the method of appearing reagents: Final Report

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