PACOMA : Performance assessment of the geological disposal of medium-level and alpha waste in a clay formation in Belgium
Performance assessment studies were undertaken on the geological disposal of medium-level and alpha-bearing waste types in the Boom clay layer at the Mol site (Belgium). The analysis indicated that scenarios of normal evolution, human intrusion (the sinking of a water well), climatic change, secondary glaciation effects and faulting are all relevant. The calculations performed show that most radionuclides decay to negligible levels within the first metres of the clay barrier. Only a few fission and activation products (such as C-14, I-129, Se-79), and some actinides of the Np-237 and the uranium decay series can eventually reach the biosphere. The maximum dose rates arising from the disposal of medium-level and alpha waste, as evaluated by deterministic "best estimate" calculations, are as low as 2 x 1.0 E-10 Sv/y for river pathways and 0.1 microSv/y for a soil pathway in the case of the normal evolution scenario. In the case when the sinking of a water well into the 160 m deep aquifer in the vicinity of the repository is considered together with climatic change, the maximum calculated annual dose rises to a value of 7 microSv/y. The maximum dose rate evaluated by stochastic calculation is 300 microSv/y for a combined scenario which considers all scenarios not affecting the integrity of the clay barrier. The evaluation of the fault scenario has shown that the occurrence of a fault through the repository should not lead to an increase of the maximum calculated dose rates.
Bibliographic Reference: EUR 13042 EN (1990) 583 pp.
Record Number: 199110930 / Last updated on: 1994-12-02
Original language: en
Available languages: en