RD&D-Programme 2004 - SKB

Newfound knowledge since RD&D 2001
Uppsala University has measured the thermal emittance of a small number of copper specimens
taken from those parts of the canister which have undergone all the steps in the fabrication
process, including the sealing weld. Despite the fact that the welds exhibited oxidation clearly
visible to the eye, the emissivity in the infrared range was low (0.06–0.11). The values are not
expected to change during the time it takes to achieve full water saturation in the buffer in the
deposition hole. After full water saturation, the thermal emittance is of no importance.
Programme
The field is judged today not to require any further research, development or demonstration.
New developments are being monitored and will be acted on when appropriate.
15.1.5 Hydrovariables
The hydrovariables – i.e. water pressures, water flows and gas flows – are not relevant to
describe initially, since the canister is assumed to be intact.
15.1.6 Mechanical stresses
Conclusions in RD&D 2001 and its review
Some activities are planned within the framework of the EU project SFS, in which SKB is also
participating, see section 15.1.2. No direct viewpoints were offered in the review.
Newfound knowledge since RD&D 2001
No new knowledge has been forthcoming.
Programme
The field is judged today not to require any further research, development or demonstration.
New developments are being monitored and will be acted on when appropriate.
15.1.7 Total radionuclide inventory
Conclusions in RD&D 2001 and its review
SKI has called for a validation of calculation models for certain nuclides (for example 36 Cl, 79 Se
and 126 Sn) as well as an account of the importance of other burnups and fuel types, for example
Mox fuel. SKI also requests an account of the total inventory of radionuclides as a function of
time and space in all parts of the fuel assembly.
Newfound knowledge since RD&D 2001
In SR 97, radionuclide inventories were calculated for burnups of 38 and 55 MWd/kgU for
BWR fuel and 42 and 60 MWd/kgU for PWR fuel. The uncertainties in the calculations were
discussed in /15-4/. In the calculations for SR 97, however, only inventories from BWR fuel
with a burnup of 38 MWd/kgU were used. The differences in nuclide inventory with respect to
burnup are often small. Figure 15-1 shows the inventory of radionuclides for different burnups
(normalized to BWR 38 and corrected for decay heat). Table 15-2 shows a comparison of the
calculated inventories of radionuclides in SR 97 in the Swiss Project Opalinus and the Belgian
Safir-2.
It is clear from the data that neither assumed burnup nor calculation tool has any decisive
influence on the calculated inventory.
RD&D-Programme 2004 165