chemical durability of high level nuclear waste forms

Model
ANNALES DE CHIMIE - science
des matériaux
CHEMICAL DURABILITY OF HIGH LEVEL NUCLEAR WASTE FORMS
Patrick TROCELLIER
CEA - CNRS Laboratoire Pierre Süe, Centre d’Etudes de Saclay, 91191 Gif sur Yvette Cedex, France.
12 lines maximum
Abstract - Amorphous and crystalline solids considered as potential host matrices for specific
immobilization of long-lived radionuclides are reviewed. Based on the available literature, their longterm behaviour is described in terms of dissolution rate and radiation effects. Presently, the most
interesting waste forms have been clearly identified for each family: glasses, glass ceramics,
phosphates, titanates, silicates and oxides. Strong research efforts have to be pursued not for proposing
new matrices but in order to complete the database on chemical durability, irradiation behaviour and
mechanical properties of selected solids. Moreover, studies have to be performed to evaluate the
relationships between radiation effects, mechanical constraints and alteration mechanisms.
Résumé - Durabilité chimique des matériaux de confinement des déchets nucléaires de haute
activité. Les matériaux amorphes ou cristallins envisagés comme matrices spécifiques de confinement
des radionucléides sont passés en revue. En s’appuyant sur les travaux déjà publiés, un point est fait sur
leur comportement à long terme et en particulier sur leur durabilité chimique ainsi que sur leur
résistance à l’irradiation. Aujourd'hui, les matériaux les plus intéressants sont identifiés pour chacune
des catégories envisagées : verres, vitrocéramiques, phosphates, titanates, silicates et oxydes. Plutôt que
de proposer de nouvelles matrices de confinement, il faut maintenant s'efforcer de compléter la base de
données sur la durabilité chimique, les effets d'irradiation et les propriétés mécaniques des matériaux
sélectionnés. Il faut en outre préciser les conséquences du couplage entre ces différentes propriétés.
Paragraph : 1 cm
1. INTRODUCTION
The alternative encountered by nuclearized countries to safely optimize the back-end of their
own uranium electronuclear cycle is: to store directly spent fuel in suitable disposal facilities, or to
reprocess the spent fuel in order to remove fissile materials [1].
Reprints : P. Trocelier, CEA - CNRS Laboratoire Pierre Süe, Centre d’Etudes de Saclay, 91191 Gif sur
Yvette Cedex, France.
1.1. Experimental
The experiments were conducted following the previous description. (1 interligne avant, 1
interligne après le titre)
1.1.1. Materials. Magnetic targets were designed…. niveau (1 interligne avant). Ce titre est suivi
immédiatement du texte, sans retour à la ligne.
Table I. Main long-lived radionuclides [1].
Radionuclide
79
Se
90
Sr
93
Zr
99
Tc
107
Pd
126
Sn
129
I
135
Cs
137
Cs
151
Sm
Half-life (y)
7 x 104
28
1.5 x 106
2.1 x 105
6.5 x 106
105
1.57 x 107
2 x 106
30
93
Radionuclide
237
Np
238
Pu
239
Pu
240
Pu
241
Pu
242
Pu
241
Am
243
Am
244
Cm
245
Cm
Half-life (y)
2.14 x 106
87.7
2.41 x 104
6569
14.4
3.7 x 105
432.2
7380
18.1
8500
Table II gives a simplified classification of potential investigated waste forms, exclusively based
on their structural nature: amorphous, crystalline, composite. Among amorphous materials, alkali
borosilicate and phosphate glasses are considered as generic waste forms able to immobilize fission
products, activation products and actinides. SYNROC and one of the crystalline phosphate form, Na-Zr
phosphate (NZP), are also generic waste forms. SYNROC is the only multiphased ceramic selected for
nuclear waste confinement. Glass ceramic forms have recently appeared as good candidates for nuclear
waste hosting [2] ; the radionuclide is preferentially trapped in the crystalline phase surrounded by a
glassy envelop. Two variants exist for glass ceramics :
The equations are centered and numbered (on the right) :

 5 / x
(1)
3 -1
Differential Pore Volume, dV/dlog(D) / cm g
4
specimen I
specimen II
specimen III
Mesopores
Macropores
3
2
1
0
2
10
100
Pore Diameter, D / nm
Figure 1. Figure centered in Black and White - Captions (left justification) - Labels = ARIAL
5. REFERENCES
[1]
R. Turlay, Les déchets nucléaires. Les Editions de Physique, Les Ulis, 1997.
[4]
R.C. Ewing, W.J. Weber and F.W. Clinard Jr., Radiation effects in nuclear waste forms for
high level radioactive waste, Progress in Nuclear Energy 29 (2) (1995) 63-127.
R.C. Ewing, W.J. Weber and W. Lutze, Ceramics : Durability and radiation effects. Report
CONF-951259, 1995.
[7]
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