Retardation mechanism studies for performance assessments

Kari Rasilainen, Pirkko Hölttä, Marja Siitari-Kauppi, Juhani Suksi, Jarmo Lehikoinen, Matti Valkiainen, Jussi Timonen, Antero Lindberg, Nuria Marcos

Research output: Book/ReportReport

Abstract

Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages90
ISBN (Electronic)951-38-5825-1
ISBN (Print)951-38-5824-3
Publication statusPublished - 2001
MoE publication typeNot Eligible

Publication series

SeriesVTT Tiedotteita - Meddelanden - Research Notes
Number2096
ISSN1235-0605

Fingerprint

performance assessment
sorption
natural analog
modeling
matrix
bedrock
channel flow
boulder
repository
radioactive waste
diffusivity
helium
radionuclide
anion
experiment
porosity
permeability
timescale
mineral
gas

Keywords

  • nuclear waste management
  • repositories
  • performance testing
  • radionuclides
  • migration
  • diffusion
  • sorption
  • modelling
  • bedrock
  • porosity

Cite this

Rasilainen, K., Hölttä, P., Siitari-Kauppi, M., Suksi, J., Lehikoinen, J., Valkiainen, M., ... Marcos, N. (2001). Retardation mechanism studies for performance assessments. Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Meddelanden - Research Notes, No. 2096
Rasilainen, Kari ; Hölttä, Pirkko ; Siitari-Kauppi, Marja ; Suksi, Juhani ; Lehikoinen, Jarmo ; Valkiainen, Matti ; Timonen, Jussi ; Lindberg, Antero ; Marcos, Nuria. / Retardation mechanism studies for performance assessments. Espoo : VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).
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Rasilainen, K, Hölttä, P, Siitari-Kauppi, M, Suksi, J, Lehikoinen, J, Valkiainen, M, Timonen, J, Lindberg, A & Marcos, N 2001, Retardation mechanism studies for performance assessments. VTT Tiedotteita - Meddelanden - Research Notes, no. 2096, VTT Technical Research Centre of Finland, Espoo.

Retardation mechanism studies for performance assessments. / Rasilainen, Kari; Hölttä, Pirkko; Siitari-Kauppi, Marja; Suksi, Juhani; Lehikoinen, Jarmo; Valkiainen, Matti; Timonen, Jussi; Lindberg, Antero; Marcos, Nuria.

Espoo : VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).

Research output: Book/ReportReport

TY - BOOK

T1 - Retardation mechanism studies for performance assessments

AU - Rasilainen, Kari

AU - Hölttä, Pirkko

AU - Siitari-Kauppi, Marja

AU - Suksi, Juhani

AU - Lehikoinen, Jarmo

AU - Valkiainen, Matti

AU - Timonen, Jussi

AU - Lindberg, Antero

AU - Marcos, Nuria

PY - 2001

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N2 - Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.

AB - Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.

KW - nuclear waste management

KW - repositories

KW - performance testing

KW - radionuclides

KW - migration

KW - diffusion

KW - sorption

KW - modelling

KW - bedrock

KW - porosity

M3 - Report

SN - 951-38-5824-3

T3 - VTT Tiedotteita - Meddelanden - Research Notes

BT - Retardation mechanism studies for performance assessments

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Rasilainen K, Hölttä P, Siitari-Kauppi M, Suksi J, Lehikoinen J, Valkiainen M et al. Retardation mechanism studies for performance assessments. Espoo: VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).