Variations in 234U/238U activity ratios in groundwater: A key to flow system characterisation?

Juhani Suksi (Corresponding Author), Kari Rasilainen, Petteri Pitkänen

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)

Abstract

Two key questions concerning geological disposal of high-level radioactive waste are (i) how robust is the barrier system during long term disturbances and (ii) do we know the possible disturbances well enough? One step towards answers is to study how groundwater flow systems have behaved in the past. Studying naturally occurring radioactive tracers in groundwater offers useful information. Uranium isotopes 234U and 238U are oft-used tracers. A characteristic of the 234U/238U activity ratio (AR) is its considerable variation in groundwater. It is known that the reason for variation is isotopic fractionation at the rock–water interface. However, the reason why AR varies in groundwater is not clear. We tried to answer this question by carefully examining the geochemical and nuclear chemical origins of U isotopic fractionation and by studying a large body of U data from Finnish and Swedish investigation sites. We found that despite large variations in AR and U concentrations, the respective 234U and 238U activities show a correlation which contains useful information of the flow system behaviour which is in line with other hydrochemical data.
Original languageEnglish
Pages (from-to)556-571
Number of pages16
JournalPhysics and Chemistry of the Earth
Volume31
Issue number10-14
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed
EventThe 10th international conference on the chemistry and migration of actinides and fission products in the geosphere - Avignon, France
Duration: 18 Sep 200523 Sep 2005

Fingerprint

ground water
Groundwater
isotopic fractionation
Fractionation
groundwater
fractionation
Radioactive Tracers
uranium isotope
Radioactive Waste
tracers
disturbance
Uranium
disturbances
Groundwater flow
site investigation
uranium isotopes
Isotopes
radioactive waste
groundwater flow
disposal

Keywords

  • 234u/238u activity ratio
  • a-recoil
  • groundwater
  • U-series disequilibrium
  • glacial processes
  • groundwater flow
  • radionuclide migration
  • radionuclides
  • nuclear waste

Cite this

@article{68b27b596e2e49fe99508f1ae84278cf,
title = "Variations in 234U/238U activity ratios in groundwater: A key to flow system characterisation?",
abstract = "Two key questions concerning geological disposal of high-level radioactive waste are (i) how robust is the barrier system during long term disturbances and (ii) do we know the possible disturbances well enough? One step towards answers is to study how groundwater flow systems have behaved in the past. Studying naturally occurring radioactive tracers in groundwater offers useful information. Uranium isotopes 234U and 238U are oft-used tracers. A characteristic of the 234U/238U activity ratio (AR) is its considerable variation in groundwater. It is known that the reason for variation is isotopic fractionation at the rock–water interface. However, the reason why AR varies in groundwater is not clear. We tried to answer this question by carefully examining the geochemical and nuclear chemical origins of U isotopic fractionation and by studying a large body of U data from Finnish and Swedish investigation sites. We found that despite large variations in AR and U concentrations, the respective 234U and 238U activities show a correlation which contains useful information of the flow system behaviour which is in line with other hydrochemical data.",
keywords = "234u/238u activity ratio, a-recoil, groundwater, U-series disequilibrium, glacial processes, groundwater flow, radionuclide migration, radionuclides, nuclear waste",
author = "Juhani Suksi and Kari Rasilainen and Petteri Pitk{\"a}nen",
year = "2006",
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language = "English",
volume = "31",
pages = "556--571",
journal = "Physics and Chemistry of the Earth",
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Variations in 234U/238U activity ratios in groundwater : A key to flow system characterisation? / Suksi, Juhani (Corresponding Author); Rasilainen, Kari; Pitkänen, Petteri.

In: Physics and Chemistry of the Earth, Vol. 31, No. 10-14, 2006, p. 556-571.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Variations in 234U/238U activity ratios in groundwater

T2 - A key to flow system characterisation?

AU - Suksi, Juhani

AU - Rasilainen, Kari

AU - Pitkänen, Petteri

PY - 2006

Y1 - 2006

N2 - Two key questions concerning geological disposal of high-level radioactive waste are (i) how robust is the barrier system during long term disturbances and (ii) do we know the possible disturbances well enough? One step towards answers is to study how groundwater flow systems have behaved in the past. Studying naturally occurring radioactive tracers in groundwater offers useful information. Uranium isotopes 234U and 238U are oft-used tracers. A characteristic of the 234U/238U activity ratio (AR) is its considerable variation in groundwater. It is known that the reason for variation is isotopic fractionation at the rock–water interface. However, the reason why AR varies in groundwater is not clear. We tried to answer this question by carefully examining the geochemical and nuclear chemical origins of U isotopic fractionation and by studying a large body of U data from Finnish and Swedish investigation sites. We found that despite large variations in AR and U concentrations, the respective 234U and 238U activities show a correlation which contains useful information of the flow system behaviour which is in line with other hydrochemical data.

AB - Two key questions concerning geological disposal of high-level radioactive waste are (i) how robust is the barrier system during long term disturbances and (ii) do we know the possible disturbances well enough? One step towards answers is to study how groundwater flow systems have behaved in the past. Studying naturally occurring radioactive tracers in groundwater offers useful information. Uranium isotopes 234U and 238U are oft-used tracers. A characteristic of the 234U/238U activity ratio (AR) is its considerable variation in groundwater. It is known that the reason for variation is isotopic fractionation at the rock–water interface. However, the reason why AR varies in groundwater is not clear. We tried to answer this question by carefully examining the geochemical and nuclear chemical origins of U isotopic fractionation and by studying a large body of U data from Finnish and Swedish investigation sites. We found that despite large variations in AR and U concentrations, the respective 234U and 238U activities show a correlation which contains useful information of the flow system behaviour which is in line with other hydrochemical data.

KW - 234u/238u activity ratio

KW - a-recoil

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KW - U-series disequilibrium

KW - glacial processes

KW - groundwater flow

KW - radionuclide migration

KW - radionuclides

KW - nuclear waste

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DO - 10.1016/j.pce.2006.04.007

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