In safety assessments for nuclear waste disposal, the biosphere is a completely open system, wher... more In safety assessments for nuclear waste disposal, the biosphere is a completely open system, whereas the bedrock can be treated with comparably simple boundary conditions. The bedrock has a vital role in providing and maintaining favourable conditions for the waste, but the public interest tends to focus on the biosphere. More importantly, the bedrock groundwater does arrive from the biosphere. Also, the regulations usually set the safety criteria in terms of doses occurring in the biosphere. Thus, it is reasonable to address the biosphere as a part of the disposal system, performance of which should be described based on conceptual models that cover phenomena and processes controlling radionuclide release and transport. From these, the actual assessment models and data are expected to be derived based on high-level research and expertise obtained through empirical study. In this paper, the complexity expected of a biosphere assessment within a mature safety case is discussed throug...
In Finland, Olkiluoto Island has been selected as the site for disposal of spent nuclear fuel. Wh... more In Finland, Olkiluoto Island has been selected as the site for disposal of spent nuclear fuel. When creating biosphere models for the safety assessments, local main features and processes need to be taken into account. Characteristic of the site is land uplift (6 mm/a) exposing continuously new land for colonization by plant and animal communities. The forest vegetation succession on these stony, fine-grained till soils starts from deciduous shoreline vegetation and ends in almost pure Norway spruce forests. This has enabled to study processes in soils and forests of different developmental stages, to monitor forest condition and the factors affecting it in other land uplift sites. It has also made possible gradient studies of the succession of boreal mire ecosystems without waiting thousands of years. In this paper, a methodology is described to establish a descriptive model on the development of the biosphere to indicate possible ecosystem distributions and main characteristics on the area on the basis of above-mentioned studies carried out in the area of the Gulf of Bothnia, and of results of the site investigations at Olkiluoto. The description will be used as a basis for selection of appropriate ecosystem modules and parameter values in the subsequent assessment model systems.
Tree foliage 1.622 Living branches 2.438 Dead branches 0.237 Stem wood 1.612 Stem bark 0.484 Tree... more Tree foliage 1.622 Living branches 2.438 Dead branches 0.237 Stem wood 1.612 Stem bark 0.484 Tree roots and stumps 2.029 Understorey vegetation 0.414 Acrotelm 245 Catotelm 571 Mineral subsoil (30 cm) 445
Journal of environmental radioactivity, Jan 11, 2016
The assessment processes concerning the safety of nuclear waste repositories include the modellin... more The assessment processes concerning the safety of nuclear waste repositories include the modelling of radionuclide transport in biosphere and the evaluation of the doses to the most affected humans. In this paper, a scenario, in which a contaminated lake is the water source for drinking water, irrigation water and watering of livestock, is presented. The objective of the paper is to probabilistically study the influence of lake properties as parameters in the assessment scenario. The properties of the lake are a result of previously conducted probabilistic studies, where the land uplift of the terrain surrounding the repositories and the formation of water bodies were studied in a 10,000-year time span using Monte Carlo simulation. The lake is formed at 3000 years from present day and the changing properties of the lake have been used in the study. The studied radionuclides (36)Cl, (135)Cs, (129)I, (237)Np, (90)Sr, (99)Tc and (238)U enter the lake with a rate of 1Â Bq/year. The trans...
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
In safety assessments for nuclear waste disposal, the biosphere is a completely open system, wher... more In safety assessments for nuclear waste disposal, the biosphere is a completely open system, whereas the bedrock can be treated with comparably simple boundary conditions. The bedrock has a vital role in providing and maintaining favourable conditions for the waste, but the public interest tends to focus on the biosphere. More importantly, the bedrock groundwater does arrive from the biosphere. Also, the regulations usually set the safety criteria in terms of doses occurring in the biosphere. Thus, it is reasonable to address the biosphere as a part of the disposal system, performance of which should be described based on conceptual models that cover phenomena and processes controlling radionuclide release and transport. From these, the actual assessment models and data are expected to be derived based on high-level research and expertise obtained through empirical study. In this paper, the complexity expected of a biosphere assessment within a mature safety case is discussed throug...
In Finland, Olkiluoto Island has been selected as the site for disposal of spent nuclear fuel. Wh... more In Finland, Olkiluoto Island has been selected as the site for disposal of spent nuclear fuel. When creating biosphere models for the safety assessments, local main features and processes need to be taken into account. Characteristic of the site is land uplift (6 mm/a) exposing continuously new land for colonization by plant and animal communities. The forest vegetation succession on these stony, fine-grained till soils starts from deciduous shoreline vegetation and ends in almost pure Norway spruce forests. This has enabled to study processes in soils and forests of different developmental stages, to monitor forest condition and the factors affecting it in other land uplift sites. It has also made possible gradient studies of the succession of boreal mire ecosystems without waiting thousands of years. In this paper, a methodology is described to establish a descriptive model on the development of the biosphere to indicate possible ecosystem distributions and main characteristics on the area on the basis of above-mentioned studies carried out in the area of the Gulf of Bothnia, and of results of the site investigations at Olkiluoto. The description will be used as a basis for selection of appropriate ecosystem modules and parameter values in the subsequent assessment model systems.
Tree foliage 1.622 Living branches 2.438 Dead branches 0.237 Stem wood 1.612 Stem bark 0.484 Tree... more Tree foliage 1.622 Living branches 2.438 Dead branches 0.237 Stem wood 1.612 Stem bark 0.484 Tree roots and stumps 2.029 Understorey vegetation 0.414 Acrotelm 245 Catotelm 571 Mineral subsoil (30 cm) 445
Journal of environmental radioactivity, Jan 11, 2016
The assessment processes concerning the safety of nuclear waste repositories include the modellin... more The assessment processes concerning the safety of nuclear waste repositories include the modelling of radionuclide transport in biosphere and the evaluation of the doses to the most affected humans. In this paper, a scenario, in which a contaminated lake is the water source for drinking water, irrigation water and watering of livestock, is presented. The objective of the paper is to probabilistically study the influence of lake properties as parameters in the assessment scenario. The properties of the lake are a result of previously conducted probabilistic studies, where the land uplift of the terrain surrounding the repositories and the formation of water bodies were studied in a 10,000-year time span using Monte Carlo simulation. The lake is formed at 3000 years from present day and the changing properties of the lake have been used in the study. The studied radionuclides (36)Cl, (135)Cs, (129)I, (237)Np, (90)Sr, (99)Tc and (238)U enter the lake with a rate of 1Â Bq/year. The trans...
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal fac... more In Finland, Olkiluoto Island has been selected for constructing a spent nuclear fuel disposal facility. With the approaching licensing step, submitting the application for nuclear construction licence in 2012, all components of the safety case are becoming more site-specific. In order to assess compliance with regulatory requirements, a prospective deterministic dose assessment methodology based on the ICRP concept of assessing doses to the representative person was developed and implemented in the interim safety case 2009, to be further refined for the safety case 2012. To facilitate the assessment of doses to the most exposed people and other people at the evolving site, full dose distributions are derived, comprising the dose to each potentially exposed person in each generation.
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Papers by Ari Ikonen