IMMOBILIZATION OF RADIOACTIVE IODINE IN IMMOBILIZATION OF RADIOACTIVE IODINE IN PHOSPHATE GLASSPHOSPHATE GLASS

T. Lemesle1,2, F.O. Méar1, L. Campayo2, O. Pinet2, L. Montagne1

1 Unité de Catalyse et Chimie du Solide - UMR-CNRS 8181 - Université Lille Nord de France, F-59652 Villeneuve d’Ascq, France

2DEN/DTCD/SECM/LDMC, CEA Marcoule, BP 17171, 30207 Bagnols sur Cèze, France

Tg variation as a function of the formulation

Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181USTL - Bâtiment C3 - 59655 Villeneuve d’Ascq Cedex - France - +33 (0)3 20 43 49 11

Email : thomas.lemesle@ed.univ-lille1.fr - http://uccs.univ-lille1.fr

Many thanks to all the following organizations for their kind contribution to this work

References :[1] CAMPAYO ET AL., PROJET MATINEX [4] KAWAMURA ET AL., SOLID STATE IONICS, 2002[2] DARAB ET AL., MRS, 1999 [5] VAN WÜLLEN ET AL., SOLID STATE SCIENCES, 2005[3] MINAMI ET  AL., J. ELECTROCHEM. SOC., 1977

Glass system: Glass system: AgAg22O – (1-x) PO – (1-x) P22OO5 5 -- AlAl22OO33 – x B – x B22OO33 – AgI – AgI

Density variation as a function of the formulation

Structural variations as a function of the formulation

A linear increase in density is observed.

Addition of AgI increases density whatever the glasses; however, the increase is more important in phosphate glasses than in boro-phosphate glasses.

An increase in the AgI amount leads to a decrease of Tg.

For AgI-bearing glasses, impact on the Tg is more important for glasses with boron substituted for a small amount of phosphate and having a low Ag/P ratio.

No more Tg variations are observed even with modified Ag/P ratios at nearly 1% of iodine content by volume.

Addition of Al2O3 moves the chemical shift to the left with a higher fraction of Qn-1 units (shorter phosphate chain than Qn).

Even with Al2O3, addition of AgI moves the spectra to the right.

(ppm)-35-30-25-20-15-10-505101520253035

AgI-AgPO3 (1% vol)

AgI-Ag4P2O7 (1% vol)

AgI-Ag5P3O10 (1% vol)

Ag5P3O10

AgPO3

Ag4P2O7

Q2Q1

(ppm)-30-25-20-15-10-50510152025303540455055606570

AgI-Ag4P2O7-5Al (1% vol)

Ag4P2O7-5Al

AgI-Ag5P3O10-5Al (1% vol)

Ag5P3O10-5Al

AgI-AgPO3-5Al (1% vol)

AgPO3-5Al

Al(4) Al(5) Al(6)

Al(PO3)3 [A]AlPO4

Tg increases with the addition of alumina

Addition of Al2O3 in AgI glasses having high Ag/P ratios is found to be more efficient

Substitution of P2O5 by B2O3 and then addition of Al2O3 cause a high increase of Tg

Increase in Ag/P decreases Tg

Al2O3 substitution for P2O5 has no significant effect on Tg

High density for silver phosphate glasses

Al2O3 substituted for P2O5 has more effect on the density than B2O3 substituted for P2O5.

An increase in the Ag/P ratio increases glass density.

Impact on density with the addition of Al2O3 is crucial on glasses having a high Ag/P.

With the incorporation of higher AgI amounts, broad peaks become narrower. Broad peaks correspond to different sites for silver cations [4].

The addition of Al2O3 changes the chemical shift values. It is explained by the increase in bond length of Ag-O [5].

(ppm)-30-25-20-15-10-50510152025303540455055606570

AgPO3 – 3Al

AgPO3 – 3Al + 5B (B sub. for P)

AgI-AgPO3-3Al (1% vol)

AgI - AgPO3 – 3Al + 5B (B sub. for P)

Al(5) Al(6)

Al(PO3)3 [A]

Lower tendencies to the crystallisation by addition of AgI in silver aluminophosphate glasses with substitution of B2O3 for P2O5

With AgI, aluminum changes from Al(6) to Al(5) plus Al(6).

0.00 0.25 0.50 0.75 1.00

0.00

0.25

0.50

0.75

1.00 0.0

0.2

0.4

0.6

0.8

1.0

Al2

O3

Ag2

O

P2O

5

AgPO3

+ x Al2

O3

Ag5P

3O

10 + x Al

2O

3

Ag4P

2O

7 + x Al

2O

3

Ag3

PO4

7% : Al2

O3

incorporation limit

ConclusionIn this study, B2O3 and Al2O3 were added and/or substituted for phosphate in iodine-bearing glasses. This was done to find a phosphate glass having a high iodine content, an intermediate Tg (> 180 °C) and no crystallisations. The results suggest that to meet the above-mentioned criteria, the glass has to have less than 5% of Al2O3 and a low Ag/P ratio. The formulation can even be improved by substituting B2O3 for P2O5. Finally, the finding suggest that the thermal and structural properties of glasses are highly influenced by the incorporation of AgI and this change will be deeply studied in further investigations.

Variation of TVariation of Tgg as a function of iodine content as a function of iodine content

Variation Variation of Tg as a function of the O/P ratio in the glass of Tg as a function of the O/P ratio in the glass systemsystem

AgAg22O – (1-x) PO – (1-x) P22OO5 5 -- AlAl22OO33 – x B – x B22OO33 – AgI – AgI

100

120

140

160

180

200

220

240

260

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Tg (

C)

% vol of iodine

AgI-AgPO3-3Al

AgI-Ag5P3O10-3Al

AgI-Ag4P2O7-3Al

AgI-AgPO3-3Al-5B

°

Variation Variation of density as a function of the O/P ratio in the glass of density as a function of the O/P ratio in the glass systemsystem

AgAg22O – (1-x) PO – (1-x) P22OO5 5 -- AlAl22OO33 – x B – x B22OO33 – AgI – AgI

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

6.2

6.4

2.90 3.00 3.10 3.20 3.30 3.40 3.50 3.60 3.70 3.80 3.90 4.00

Den

sity

O/ P

substitutionB for P

+ xAl2O3

(x=0 ; 3 ou 5)

+ x% vol iodine (x=0->1)

increase of Ag/P

substitutionAl for P

AgI-AgPO3

(1% vol I)

AgI-Ag3PO4

(1% vol I)

AgI-Ag4P2O7

(1% vol I)

AgI-Ag5P3O10

(1% vol I)

AgPO3

Ag5P3O10

AgPO3 -5B2O3

(B sub. for P)

Ag4P2O7

Ag3PO4

4.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Gla

ss d

ensi

ty

% vol of iodine

AgI-AgPO3-3Al

AgI-Ag5P3O10-3Al

AgI-Ag4P2O7-3Al

AgI-AgP-3Al-5B

75

100

125

150

175

200

225

250

275

300

2.90 3.00 3.10 3.20 3.30 3.40 3.50 3.60 3.70 3.80 3.90 4.00

Tg (

C)

O/ P

AgI-AgPO3

(1% vol I)

AgI-Ag3PO4

(1% vol I)

AgI-Ag4P2O7

(1% vol I)

AgI-Ag5P3O10

(1% vol I)

AgPO3

Ag5P3O10

AgPO3 -5B2O3

(B sub. for P)

substitutionB for P

+ xAl2O3

(x=0;3 ou 5)

+ x% vol iodine (x=0->1)

increase of Ag/P

substitutionAl for P

°

Variation of density as a function of iodineVariation of density as a function of iodine

Influence of the incorporation of AgI on the structure as a function of Ag/P by Influence of the incorporation of AgI on the structure as a function of Ag/P by 3131P NMR P NMR

Addition of AgI for different ratios of Ag/P changes the chemical shift. The chemical shift is shifted towards the highest Qn.

Influence of the incorporation of AlInfluence of the incorporation of Al22OO3 3 and and AgI on the structure by AgI on the structure by 3131P and P and 2727Al NMR Al NMR

(ppm)-50-45-40-35-30-25-20-15-10-505101520253035404550

AgI-Ag4P2O7-5Al (1% vol)

Ag4P2O7-5Al

Ag4P2O7

AgI-Ag5P3O10-5Al (1% vol)

Ag5P3O10-5Al

Ag5P3O10

AgI-AgPO3-5Al (1% vol)

AgPO3-5Al

AgPO3

Q2Q1Q0

Al(PO3)3 [A]AlPO4

Without AgI, aluminum is in an octahedral form, Al(6), except for Ag/P < 2.

With addition of AgI, for Ag/P >1, aluminium exhibits two environments: Al(5) and Al(6), respectively.

Crystallisation of aluminum occurs in AgI-AgPO3-5Al: narrow peaks for Al(PO3)3 and AlPO4.

Influence of the incorporation of AgI and substitution in silver metaphosphate Influence of the incorporation of AgI and substitution in silver metaphosphate glasses glasses

by by 109109Ag, Ag, 3131P and P and 2727Al NMRAl NMR

Substitution of B2O3 for P2O5 has an effect (chemical shift moved to the left) even with 5%mol

(ppm)-50-45-40-35-30-25-20-15-10-505101520253035

AgPO3+ 5B (B sub. for P)

AgPO3

AgPO3 – 3Al

AgPO3 – 3Al + 5B(B sub. for P)

AgI-AgPO3-3Al (1% vol)

AgI - AgPO3 – 3Al + 5B (B sub. for P)

Q1 Q2

Al(PO3)3 [A]

P-O-Al zone

P-O-B zone

Analysis of incorporation of AgI and AlAnalysis of incorporation of AgI and Al22OO33 by by 109109Ag NMRAg NMR

Analysis of substitution of BAnalysis of substitution of B22OO33 for P for P22OO55 by by 3131P and P and 2727Al NMRAl NMR

(ppm)-400-350-300-250-200-150-100-50050100150200250300350400450500550600650700750

AgPO3

AgI-AgPO3 (1% vol)

AgPO3-3Al

AgI –AgPO3-3Al (1% vol)

AgI –AgPO3-5Al (1% vol)

AgPO3430 ppm

24 ppm

ratioratio

amount

Iodine-129, extracted during the reprocessing of spent nuclear fuel, is considered as a long-lived isotope (half-life: 15.7 million years). It is characterized by a high mobility in geologic environment as well as by its strong tendency to volatilization. Its management within the framework of a safe disposal in a deep geological repository requires the definition of a conditioning matrix.Two main types of conditioning matrices, mentioned in the available literature, seem particularly interesting: the ceramic matrices belonging to the system of lead-bearing vanadates [1 ] and the glassy matrices like borosilicate glasses [2] or phosphate glasses [3]. It is on the latter system that this PhD work is focused (127I is used as an analogue for 129I).