JRP CALL information
Supported By

European Commission

Short description of the work
Nowadays PUREX process is widely used in the spent nuclear fuel (SNF) reprocessing. In this process the key components, shuch as U and Pu, are extracted with tri-n-butyl phosphate from nitric acid solitions, wherein the main impurity is Tc. In nitric acis solutions Tc usually presents as pertechnetate- ion. For reprocessing of SNF solutions containig Tc we proposed Ferroin nitrate, complex of iron(II) with o-phenantroline, which could form poorly soluble compounds with pretechnetate ions and, consequently, could be used as a to precipitate Tc.
The experiments carried out in Chalmers University were focused on determination of the coprecipitation of technetium with other elements occuring in the SNF solutions, the irradiation stability of the Ferroin nitrate and its influence on Tc precipitation and its coprecipitation with other metals.
For these purposes precipitation of Mo with Feerroin nitrate from the solution with the concentration of nitric acid 0.5, 1, 1.5, 2, 3 M at different mole ratios Ferroin/Tc was carried out. The coprecipitation of Mo with Tc in such nitric acid solutions was studied at different mole ratios Ferroin/Tc, as well. The same experiments were carried out for Ru. Ru was also precipitated with Ferroin nitrate from nitric acid solutions in the presence of Tc and with out it. It was found that Ru couldn’t be precipitated using Ferrroin nitrate from nitric acid solution and it is not coprecipitated with Tc, as well. But in the case of Mo Ferroin nitrate could be used as a precipitant to recover it from the solutions with the concentration of nitric acid from 0,5 up to 3 M.
The precipitation of Tc from the concentrated high active raffinate (HAC- high active concentrate) of PUREX process was carried out at different Ferroin/Tc mole ratios. This raffinate contained Sr, Zr, Mo, Pd, Sn, Cs, Ba, La, Ce, Pr, Nd, Sm, U, Pu (which was replaced with Th in these experiments) and Am.
These experiments showed that other elements also coprecipitated simultaneously with Tc using Ferroin nitrate, however all Am stays in mother solution.
To study the influence of the irradiation of the precipitant on Tc precipitation from pure nitric acid solution,the solution of Ferroin nitrate were irradiated. These initial series of irradiation were 50 kG and 150 kG. The irradiated solutions of the precipitant were used to precipitate Tc in the presence of Mo from nitric acid solutions and from HAC solution. The precipitation was carried out at different Ferroin/Tc mole ratios.
These experiments showed that Ferroin nitrate after irradiation oxidizes quicker in nitric acid solutions than nonirradiated one.
Also, practically all received sediments were studied with XRD and SEM analyses. SEM analyses showed that different poorly soluble compounds with variable composition form during the precipitation.

Main visitor contact data
Name: Tatina Boytsova
Organisation: JSR "Khlopin's Radium Institute"

JRP Identification
JRP nr: TALI-C06-02
JRP title: Fundamental study of Tc precipitation with Ferroin nitrate from SNF reprocessing solutions with the aim to evaluate the possibility of reprecipitation and a role that irradiated precipitant plays in it
JRP scope: Scope 1: Actinide separation chemistry

Visited Associated Pooled Facility
Visited APF during the stay: Chalmers - Hot Lab
Name of the APF Contact Person: Stefan Allard

Other APF and organisation involved in the JRP
Other organisations involved:
Other APF involved in the project: Chalmers - Hot Lab

Description of the work done at the associated pooled facility
Start date of the stay: 10/19/2015
End date of the stay: 11/29/2015
Quantity of access: 30
Access Unit: Days