Euradwaste '08 - EU Bookshop - Europa

A project would be justified to determine the underlying sorption processes. It would reflect that
national programmes are reaching a state of development where coming closer to implementation
requires generation of a more acceptable base for sorption assessment. Such a project would build
on the very broad existing competence. It would also benefit from the use of advanced analytical
techniques, especially recent developments where the spatial resolution is rapidly improving for
determination of elemental composition and chemical states on different solids/minerals involved.
Finally, the access to very elaborate site-specific data available through recent site characterization
programmes provides for direct natural analogue / real system comparison and verification.
2. In-depth interpretation and integration of existing data from the large FP6 Disposal
IP’s in view of the application to the Safety Case.
FP6 disposal investigations build around the waste emplacement technology, near-field and farfield
processes, and Performance Assessment (PA)/ the Safety Case. These IP’s complementary to
each other are ESDRED, NF-PRO, FUNMIG and PAMINA. Each of these Integrated Projects
deals with SC Topics, either with reference to the technology or science areas dealt with or certain
PA/SC aspects. The outcome is implemented in present advanced national programmes. An added
value may be expected from synthesizing the outcome of these four IP’s with respect to providing
(i) an overall view of the outcome in terms of the advances in the state of knowledge for European
national programmes at their different levels of development, (ii) an evaluation and prioritisation of
the open issues identified in the list of suggestions for further work and (iii) conclusions and recommendations
for future Euratom disposal programme activities. The latter two aspects are important
elements also in building a disposal technology platform, presently under development.
3. Geochemical in-situ experiments, micro analytics
In order to increase confidence in the performance assessment of nuclear waste disposal, verification
of the speciation of radionuclides through in situ measurements is an important issue. Indeed,
the computation of the migration of radionuclides in the near-field and far-field rely on thermodynamic
databases, based on compilations and surface laboratory experiments. Direct or indirect evidence
of in situ speciation have seldom been gathered. Taking advantage of existing underground
laboratory facilities, it is a real challenge to be able to confront measurements and predictions. Recent
progress in analytical chemistry (spectroscopy, electrochemistry) renders this goal achievable.
4. Isotopic dilution and exchange
For mobile fission products, which mostly contribute to the impact of nuclear waste disposal, it is
relevant to increase the safety margins by looking at processes that should be able to induce a significant
retardation effect. Isotopic dilution and exchange are possible processes and need to be
confirmed. This is especially true for 14 C, 36 Cl and 129 I. Theoretical studies, together with laboratory
studies and field studies are necessary to document such processes.
Retardation processes for mobile fission and activation products ( 79 Se, 129 I, 14 C…) including
mineral reactions and nuclides
The principal radionuclides migrating through the geological barrier in recent Safety Cases (SC)
treating disposal concepts in clayrock formations are 129 I, 36 Cl, 79 Se, 41 Ca (Andra, 2005), 129 I, 36 Cl,
79 Se, 14 C organic (Nagra, 2002) and 129 I, 79 Se, 99 Tc (NIROND, 2001). In all cases except 41 Ca, this
is a result of attributing them retardation values of 1 (Kd = 0). On the other hand, for certain of
these radionuclides ( 79 Se, 129 I and 14 C organic) it is possible to hypothesize mechanisms which
364