The exercise showed that identical results for radionuclide transport in the near-field are obtained with the REPCOM code, developed by VTT and used in the TILA-99 and several other safety assessments, and with the commercial PC code PORFLOW. The analysed KBS-3V (vertical deposition hole) and KBS-3H (horizontal deposition drift) cases are geometrically fairly demanding as they include a localised release through a small hole or larger damage in the copper-iron canister. Furthermore, in the KBS-3V case there are three different release routes from the deposition hole and the above tunnel into the geosphere. Within the present exercise, the only important difference between the modelled KBS-3V and KBS-3H transport systems was the absence in KBS-3H of the tunnel section and the upper part of the deposition hole, which in KBS-3V are assumed to be backfilled with the tunnel backfill and not with compacted bentonite. The difference is significant because in TILA-99 flow of groundwater is assumed to take place through these sections of the near-field. The backfilled sections in the top of the KBS-3V deposition hole provide important release routes for long-lived nuclides as well as for cations with the assumed high mobility, especially in saline groundwater, in buffer and backfill. However, as concerns the overall results of safety assessment (release rates into the biosphere and consequent dose rates) the difference between KBS-3V and KHS-3H is significant only in scenarios with a high flow and transport of groundwater in the near-field as well as in the geosphere. Traceability and reproducibility of the analyses are enhanced by presenting thorough inputs and run scripts with explanations in the appendixes.
|Place of Publication||Olkiluoto|
|Number of pages||66|
|Publication status||Published - 2003|
|MoE publication type||D4 Published development or research report or study|
|Series||Posiva Working Report|
- spent fuel
Nordman, H., & Vieno, T. (2003). Modelling of Near-Field Transport in KBS-3V/H Type Repositories with PORFLOW and REPCOM Codes. Posiva. Posiva Working Report, No. 2003-07 http://www.posiva.fi/files/2186/POSIVA-2003-07_Working-report_web.pdf