ICRP Publication 122
Radiological Protection in Geological Disposal of Long-lived Solid Radioactive Waste
Recommended citation
ICRP, 2013. Radiological protection in geological disposal of long-lived solid radioactive waste. ICRP Publication 122. Ann. ICRP 42(3).
Authors on behalf of ICRP
W. Weiss, C-M. Larsson, C. McKenney, J-P. Minon, S. Mobbs, T. Schneider, H. Umeki, W. Hilden, C. Pescatore, M. Vesterlind
Abstract - This report updates and consolidates previous recommendations of the International Commission on Radiological Protection (ICRP) related to solid waste disposal. The recommendations given apply specifically to geological disposal of long-lived solid radioactive waste. The report explains how the ICRP system of radiological protection described in Publication 103 can be applied in the context of the geological disposal of long-lived solid radioactive waste. Although the report is written as a standalone document, previous ICRP recommendations not dealt with in depth in the report are still valid.
The 2007 ICRP system of radiological protection evolves from the previous process-based protection approach relying on the distinction between practices and interventions by moving to an approach based on the distinction between three types of exposure situation: planned, emergency and existing. The Recommendations maintains the Commission’s three fundamental principles of radiological protection namely: justification, optimisation of protection and the application of dose limits. They also maintain the current individual dose limits for effective dose and equivalent dose from all regulated sources in planned exposure situations. They re-enforce the principle of optimisation of radiological protection, which applies in a similar way to all exposure situations, subject to restrictions on individual doses: constraints for planned exposure situations, and reference levels for emergency and existing exposure situations. The Recommendations also include an approach for developing a framework to demonstrate radiological protection of the environment.
This report describes the different stages in the life time of a geological disposal facility, and addresses the application of relevant radiological protection principles for each stage depending on the various exposure situations that can be encountered. In particular, the crucial factor that influences the application of the protection system over the different phases in the life time of a disposal facility is the level of oversight or ‘watchful care’ that is present. The level of oversight affects the capability to control the source, i.e. the waste and the repository, and to avoid or reduce potential exposures. Three main time frames are considered: time of direct oversight, when the disposal facility is being implemented and is under active supervision; time of indirect oversight, when the disposal facility is sealed and oversight is being exercised by regulators or special administrative bodies or society at large to provide additional assurance on behalf of society; and time of no oversight, when oversight is no longer exercised in case memory of the disposal facility is lost.
© 2013 ICRP. Published by Elsevier Ltd.
Keywords: Geological disposal; Radioactive waste; Protecting future generations.
W. WEISS, C-M. LARSSON, C. MCKENNEY, J-P. MINON, S. MOBBS, T. SCHNEIDER, H. UMEKI, W. HILDEN, C. PESCATORE, M. VESTERLIND
Key Points
This report provides advice on application of the Commission’s 2007 Recommendations (ICRP, 2007) for the protection of humans and the environment against any harm that may result from the geological disposal of long-lived solid radioactive waste.
For the protection of the future generations, the Commission recommendations continue to rely on the basic principle that: ‘individuals and populations in the future should be afforded at least the same level of protection as the current generation’ (ICRP, 1998).
The Commission views the potential exposures to humans and the environment associated with the expected evolution of the geological disposal of long-lived solid radioactive as a planned exposure.
Application of the protection system is influenced by the level of oversight or ‘watchful care’ of the disposal facility. Three main time frames have to be considered: time of direct oversight, when the disposal facility is being operated and is under active supervision; time of indirect oversight, when the disposal facility is partly or fully sealed where indirect regulatory, administrative or societal oversight might continue; and time of no oversight, when the memory of the disposal facility has been lost.
If oversight ceases to exist in the post closure period, the disposal system is still a functioning facility and potential exposures should be considered as planned.
The different decisions to be made relating to the evolution of oversight should be discussed with stakeholders.
For application of the justification principle, waste management and disposal operations have to be considered as an integral part of the practice generating the waste. This justification should be reviewed over the lifetime of that practice whenever new and important information becomes available.
As stated in previous publications on radioactive waste management (ICRP, 1997b, 1998), the control of public exposure in the distant future through a process of constrained optimisation will obviate the direct use of individual dose limits.
Optimisation of protection is the central element of the stepwise design, construction, and operation of a geological disposal facility.
Optimisation has to be understood in the broadest sense as an iterative, systematic, and transparent evaluation of protective option, including Best Available Techniques, for enhancing the protective capabilities of the system and reducing its potential impacts (radiological and others).
In application of the optimisation principle, the radiological criterion for the design of a waste disposal facility recommended by ICRP is an annual dose constraint for the population of 0.3 mSv year-1 and below the annual dose limit of 20 mSv year-1 or 100 mSv in 5 years for occupationally exposed workers.
A risk constraint for the population of 1 x 10-5 year-1 is recommended when applying an aggregated approach combining probability of the exposure scenario and the associated dose.
In the very long term, dose and risk criteria should be used for the comparison of options rather than a means of assessing health detriment.
For natural events included in the design-basis evolution, the Commission recommends selection of dose or risk constraints in the band for planned exposure situations.
For severe natural disruptive events not taken into account in the design-basis evolution and inadvertent human intrusion, application of the risk or dose constraint does not apply. In that case, if the events were to occur while there is still (direct or indirect) oversight of the disposal facility, the ensuing exposure situation (emergency or existing) should be considered by the competent authority, and the relevant protection measures should be implemented.
For inadvertent human intrusion, the design and siting of the facility should include features to reduce the possibility of such events.
Judgement of the quality of the system design developed or implemented has to be made, and reviewed critically when needed, in a well-structured and transparent process, with the involvement of all relevant stakeholders.
General implementation of the Commission’s recommendations requires a management system that integrates safety, health, environmental, security, quality, and economic elements, with safety being the fundamental goal.
For planned exposure situations, doses should be assessed on the basis of the annual dose to the representative person.
Consideration of environmental protection, where appropriate, should be part of the risk-informed decision making.
Executive Summary
(a) This report provides advice on application of the Commission’s 2007 Recommendations (ICRP, 2007) for the protection of humans and the environment against any harm that may result from the geological disposal of long-lived solid radioactive waste. It illustrates how the key protection concepts and principles of Publication 103 (ICRP, 2007) should be interpreted, and how they apply over the different time frames a geological disposal facility for long-lived solid radioactive waste would have to provide radiological protection (see Fig. A).
(b) The goal of a geological disposal facility is to contain and isolate the waste in order to protect humans and the environment for time scales that are comparable with geological time scales. At large distances from the surface, changes are particularly slow. Given the distance from the surface and the selection of appropriate sites, the potential for human intrusion is limited. Radioactivity is increasing with time, and any release will be delayed and further diluted by a properly chosen geological formation. Geological disposal is recognised by international organisations as especially suited for high-level radioactive waste or spent fuel where long-term containment and isolation is required. Geological disposal may also be used for other long-lived wastes, especially when a similar need for long-term protection applies.
(c) One of the important factors that influence application of the protection system over the different phases of the life time of a geological disposal facility is the level of oversight or ‘watchful care’ of the disposal facility. The level of oversight directly affects the capability to control the source, and to avoid or reduce some exposures. Three main time frames have to be considered: time of direct oversight, when the disposal facility is being operated and active control is taking place (operational phase); time of indirect oversight, when the disposal facility is partly (backfilling and sealing of drifts) or fully sealed (postclosure period) where indirect regulatory or societal oversight might continue for a period and then be supplemented or replaced by indirect oversight (e.g. monitoring of the performances of the repository and the pathways for potential radionuclide releases, verification that restrictions on land control use are being met, maintaining records and memory of the facility, etc.);
and time of no oversight (postclosure period), when the memory of the disposal facility is lost. In the periods of indirect or no oversight, once the facility is sealed, protection relies on the passive controls built into the facility at the time of its design, licensing, and operation.
(d) The design and associated safety case of a geological disposal facility address a series of evolutions with different probabilities that may be defined by regulation. Besides these design-basis evolutions, the developer/implementer, overseen by the regulator and society, may want to assess evolutions in non-design-basis conditions in order to judge the robustness of the facility.
(e) This report describes the radiological concepts and criteria that should be used by the designer and/or operator of the facility, the regulator, and the concerned stakeholders. Various dose and risk constraints are used for assessment of the safety and radiological protection of a geological disposal facility for long-lived radioactive waste. Optimisation addresses the main aim of a disposal facility (i.e. the radiological protection of humans and the environment). Optimisation of protection is the central element of the stepwise construction and implementation of a geological disposal facility. It has to cover all elements of the system, including the societal component, in an integrated way. Important aspects of optimisation of protection must occur prior to waste emplacement, largely during the siting and design phase. The optimisation efforts can be informed by, and construction supplemented with, consideration of Best Available Techniques (BAT) as applied to all stages of disposal facility siting and design. During the implementation phase, some further optimisation is possible, but it is accepted that very little can be done to further optimise the performance of the engineered features after waste emplacement has occurred, and more so when galleries have been sealed.
(f) In the distant future, the geological disposal facility might give rise to some releases to the accessible environment, and the safety case has to demonstrate that such releases, should they occur, will be within radiological protection criteria specified as part of the regulatory requirements. In application of the optimisation principle, the reference radiological impact criterion for the design of a waste disposal facility recommended by ICRP is an annual dose constraint for the population of 0.3 mSv year-1 (ICRP, 2007), without any weighting of doses in the distant future. For doses in the future and for less likely events resulting in exposures, both categorised as potential exposures, the Commission continues to recommend a risk1 constraint for the population of 1 x 10-5 year-1 when applying an aggregated approach combining probability of the exposure scenario and the associated dose. However, Publication 103 (ICRP, 2007) also warns that effective dose loses its direct connection to health detriment for doses in the future after a time span of a few generations, given the evolution of society, human habits, and characteristics. Furthermore, in the distant future, the geosphere, the engineered system and, even more so, the biosphere will evolve in a less predictable way. The scientific basis for assessments of detriment to health at very long times into the future therefore become uncertain, and the strict application of numerical criteria may be inappropriate. In the very long term, dose and risk criteria should be used for the comparison of options rather than a means of assessing health detriment.
(g) The design-basis evolution of the geological disposal facility includes the expected evolution of the protection provided by the facility, and also events with a low probability of occurrence (less likely evolutions). It does not include either severe disturbing events of very low probability that may disrupt the facility, or inadvertent human intrusion. The exposures arising from the design-basis evolution scenarios are planned exposure situations as defined in Publication 103 (ICRP, 2007). They include potential exposures from events with low probability, which have to be considered as part of the design basis. More specifically, for exposure to be delivered in the distant future, potential exposures will have to be considered due to the considerable uncertainties surrounding such exposures (ICRP, 2007, Para. 265). If severe disturbing events outside the design basis occur while there is still oversight (direct or indirect) of the disposal facility, the ensuing situation will be considered by the competent authority at that time, and the relevant protection measures will be implemented. If a severe disturbing event occurs when there is no longer oversight of the disposal facility, there is no certainty that a competent authority will be able to understand the source of the exposure, and therefore it is not possible to consider with certainty the implementation of relevant measures to control the source. Inadvertent human intrusion into the geological disposal facility is not a relevant scenario during the period of direct or indirect oversight. In the period of no oversight, inadvertent human intrusion may occur and the consequences considered by the competent authorities at that time, if and when they understand the source of the exposure.
(h) For the design-basis evolution, the dosimetric criteria relevant to planned exposure situations are considered for assessing the safety and robustness of the disposal facility over the three main time frames. In the design stage, potential impacts of severe disturbing events may be estimated using stylised or simplified calculations. An indication of the robustness of the system could then be obtained by comparing these results with numerical values of dose or risk, if required. If this approach is adopted, the appropriate reference levels should be those for an existing exposure situation (a few mSv per year), or for an emergency exposure (in the range of 20– 100 mSv for the first year), depending on the specific scenario. If the event actually occurs in the future, the competent authority should apply the relevant protection criteria at the time.
(i) The safety case of a geological disposal facility, by including events of low probability and exposures to be delivered in the distant future, includes consideration of how to deal with potential exposures as defined by Publication 103 (ICRP, 2007).
(j) ICRP recommends that dose or risk estimates derived from these exposure assessments should not be regarded as direct measures of health effects beyond time scales of around several hundred years into the future. Rather, they represent indicators of the protection afforded by the geological disposal facility.
1 Risk is used in this document to mean ‘radiological risk’ as defined in Publication 103 (ICRP, 2007)
(k) Application of the three exposure situations and of dose limits, constraints, and reference levels as defined in Publication 103 (ICRP, 2007) during the three main time frames is indicated in Table A.
ICRP, 2013. Radiological protection in geological disposal of long-lived solid radioactive waste. ICRP Publication 122. Ann. ICRP 42(3).
Authors on behalf of ICRP
W. Weiss, C-M. Larsson, C. McKenney, J-P. Minon, S. Mobbs, T. Schneider, H. Umeki, W. Hilden, C. Pescatore, M. Vesterlind
Abstract - This report updates and consolidates previous recommendations of the International Commission on Radiological Protection (ICRP) related to solid waste disposal. The recommendations given apply specifically to geological disposal of long-lived solid radioactive waste. The report explains how the ICRP system of radiological protection described in Publication 103 can be applied in the context of the geological disposal of long-lived solid radioactive waste. Although the report is written as a standalone document, previous ICRP recommendations not dealt with in depth in the report are still valid.
The 2007 ICRP system of radiological protection evolves from the previous process-based protection approach relying on the distinction between practices and interventions by moving to an approach based on the distinction between three types of exposure situation: planned, emergency and existing. The Recommendations maintains the Commission’s three fundamental principles of radiological protection namely: justification, optimisation of protection and the application of dose limits. They also maintain the current individual dose limits for effective dose and equivalent dose from all regulated sources in planned exposure situations. They re-enforce the principle of optimisation of radiological protection, which applies in a similar way to all exposure situations, subject to restrictions on individual doses: constraints for planned exposure situations, and reference levels for emergency and existing exposure situations. The Recommendations also include an approach for developing a framework to demonstrate radiological protection of the environment.
This report describes the different stages in the life time of a geological disposal facility, and addresses the application of relevant radiological protection principles for each stage depending on the various exposure situations that can be encountered. In particular, the crucial factor that influences the application of the protection system over the different phases in the life time of a disposal facility is the level of oversight or ‘watchful care’ that is present. The level of oversight affects the capability to control the source, i.e. the waste and the repository, and to avoid or reduce potential exposures. Three main time frames are considered: time of direct oversight, when the disposal facility is being implemented and is under active supervision; time of indirect oversight, when the disposal facility is sealed and oversight is being exercised by regulators or special administrative bodies or society at large to provide additional assurance on behalf of society; and time of no oversight, when oversight is no longer exercised in case memory of the disposal facility is lost.
© 2013 ICRP. Published by Elsevier Ltd.
Keywords: Geological disposal; Radioactive waste; Protecting future generations.
W. WEISS, C-M. LARSSON, C. MCKENNEY, J-P. MINON, S. MOBBS, T. SCHNEIDER, H. UMEKI, W. HILDEN, C. PESCATORE, M. VESTERLIND
Key Points
This report provides advice on application of the Commission’s 2007 Recommendations (ICRP, 2007) for the protection of humans and the environment against any harm that may result from the geological disposal of long-lived solid radioactive waste.
For the protection of the future generations, the Commission recommendations continue to rely on the basic principle that: ‘individuals and populations in the future should be afforded at least the same level of protection as the current generation’ (ICRP, 1998).
The Commission views the potential exposures to humans and the environment associated with the expected evolution of the geological disposal of long-lived solid radioactive as a planned exposure.
Application of the protection system is influenced by the level of oversight or ‘watchful care’ of the disposal facility. Three main time frames have to be considered: time of direct oversight, when the disposal facility is being operated and is under active supervision; time of indirect oversight, when the disposal facility is partly or fully sealed where indirect regulatory, administrative or societal oversight might continue; and time of no oversight, when the memory of the disposal facility has been lost.
If oversight ceases to exist in the post closure period, the disposal system is still a functioning facility and potential exposures should be considered as planned.
The different decisions to be made relating to the evolution of oversight should be discussed with stakeholders.
For application of the justification principle, waste management and disposal operations have to be considered as an integral part of the practice generating the waste. This justification should be reviewed over the lifetime of that practice whenever new and important information becomes available.
As stated in previous publications on radioactive waste management (ICRP, 1997b, 1998), the control of public exposure in the distant future through a process of constrained optimisation will obviate the direct use of individual dose limits.
Optimisation of protection is the central element of the stepwise design, construction, and operation of a geological disposal facility.
Optimisation has to be understood in the broadest sense as an iterative, systematic, and transparent evaluation of protective option, including Best Available Techniques, for enhancing the protective capabilities of the system and reducing its potential impacts (radiological and others).
In application of the optimisation principle, the radiological criterion for the design of a waste disposal facility recommended by ICRP is an annual dose constraint for the population of 0.3 mSv year-1 and below the annual dose limit of 20 mSv year-1 or 100 mSv in 5 years for occupationally exposed workers.
A risk constraint for the population of 1 x 10-5 year-1 is recommended when applying an aggregated approach combining probability of the exposure scenario and the associated dose.
In the very long term, dose and risk criteria should be used for the comparison of options rather than a means of assessing health detriment.
For natural events included in the design-basis evolution, the Commission recommends selection of dose or risk constraints in the band for planned exposure situations.
For severe natural disruptive events not taken into account in the design-basis evolution and inadvertent human intrusion, application of the risk or dose constraint does not apply. In that case, if the events were to occur while there is still (direct or indirect) oversight of the disposal facility, the ensuing exposure situation (emergency or existing) should be considered by the competent authority, and the relevant protection measures should be implemented.
For inadvertent human intrusion, the design and siting of the facility should include features to reduce the possibility of such events.
Judgement of the quality of the system design developed or implemented has to be made, and reviewed critically when needed, in a well-structured and transparent process, with the involvement of all relevant stakeholders.
General implementation of the Commission’s recommendations requires a management system that integrates safety, health, environmental, security, quality, and economic elements, with safety being the fundamental goal.
For planned exposure situations, doses should be assessed on the basis of the annual dose to the representative person.
Consideration of environmental protection, where appropriate, should be part of the risk-informed decision making.
Executive Summary
(a) This report provides advice on application of the Commission’s 2007 Recommendations (ICRP, 2007) for the protection of humans and the environment against any harm that may result from the geological disposal of long-lived solid radioactive waste. It illustrates how the key protection concepts and principles of Publication 103 (ICRP, 2007) should be interpreted, and how they apply over the different time frames a geological disposal facility for long-lived solid radioactive waste would have to provide radiological protection (see Fig. A).
(b) The goal of a geological disposal facility is to contain and isolate the waste in order to protect humans and the environment for time scales that are comparable with geological time scales. At large distances from the surface, changes are particularly slow. Given the distance from the surface and the selection of appropriate sites, the potential for human intrusion is limited. Radioactivity is increasing with time, and any release will be delayed and further diluted by a properly chosen geological formation. Geological disposal is recognised by international organisations as especially suited for high-level radioactive waste or spent fuel where long-term containment and isolation is required. Geological disposal may also be used for other long-lived wastes, especially when a similar need for long-term protection applies.
(c) One of the important factors that influence application of the protection system over the different phases of the life time of a geological disposal facility is the level of oversight or ‘watchful care’ of the disposal facility. The level of oversight directly affects the capability to control the source, and to avoid or reduce some exposures. Three main time frames have to be considered: time of direct oversight, when the disposal facility is being operated and active control is taking place (operational phase); time of indirect oversight, when the disposal facility is partly (backfilling and sealing of drifts) or fully sealed (postclosure period) where indirect regulatory or societal oversight might continue for a period and then be supplemented or replaced by indirect oversight (e.g. monitoring of the performances of the repository and the pathways for potential radionuclide releases, verification that restrictions on land control use are being met, maintaining records and memory of the facility, etc.);
and time of no oversight (postclosure period), when the memory of the disposal facility is lost. In the periods of indirect or no oversight, once the facility is sealed, protection relies on the passive controls built into the facility at the time of its design, licensing, and operation.
(d) The design and associated safety case of a geological disposal facility address a series of evolutions with different probabilities that may be defined by regulation. Besides these design-basis evolutions, the developer/implementer, overseen by the regulator and society, may want to assess evolutions in non-design-basis conditions in order to judge the robustness of the facility.
(e) This report describes the radiological concepts and criteria that should be used by the designer and/or operator of the facility, the regulator, and the concerned stakeholders. Various dose and risk constraints are used for assessment of the safety and radiological protection of a geological disposal facility for long-lived radioactive waste. Optimisation addresses the main aim of a disposal facility (i.e. the radiological protection of humans and the environment). Optimisation of protection is the central element of the stepwise construction and implementation of a geological disposal facility. It has to cover all elements of the system, including the societal component, in an integrated way. Important aspects of optimisation of protection must occur prior to waste emplacement, largely during the siting and design phase. The optimisation efforts can be informed by, and construction supplemented with, consideration of Best Available Techniques (BAT) as applied to all stages of disposal facility siting and design. During the implementation phase, some further optimisation is possible, but it is accepted that very little can be done to further optimise the performance of the engineered features after waste emplacement has occurred, and more so when galleries have been sealed.
(f) In the distant future, the geological disposal facility might give rise to some releases to the accessible environment, and the safety case has to demonstrate that such releases, should they occur, will be within radiological protection criteria specified as part of the regulatory requirements. In application of the optimisation principle, the reference radiological impact criterion for the design of a waste disposal facility recommended by ICRP is an annual dose constraint for the population of 0.3 mSv year-1 (ICRP, 2007), without any weighting of doses in the distant future. For doses in the future and for less likely events resulting in exposures, both categorised as potential exposures, the Commission continues to recommend a risk1 constraint for the population of 1 x 10-5 year-1 when applying an aggregated approach combining probability of the exposure scenario and the associated dose. However, Publication 103 (ICRP, 2007) also warns that effective dose loses its direct connection to health detriment for doses in the future after a time span of a few generations, given the evolution of society, human habits, and characteristics. Furthermore, in the distant future, the geosphere, the engineered system and, even more so, the biosphere will evolve in a less predictable way. The scientific basis for assessments of detriment to health at very long times into the future therefore become uncertain, and the strict application of numerical criteria may be inappropriate. In the very long term, dose and risk criteria should be used for the comparison of options rather than a means of assessing health detriment.
(g) The design-basis evolution of the geological disposal facility includes the expected evolution of the protection provided by the facility, and also events with a low probability of occurrence (less likely evolutions). It does not include either severe disturbing events of very low probability that may disrupt the facility, or inadvertent human intrusion. The exposures arising from the design-basis evolution scenarios are planned exposure situations as defined in Publication 103 (ICRP, 2007). They include potential exposures from events with low probability, which have to be considered as part of the design basis. More specifically, for exposure to be delivered in the distant future, potential exposures will have to be considered due to the considerable uncertainties surrounding such exposures (ICRP, 2007, Para. 265). If severe disturbing events outside the design basis occur while there is still oversight (direct or indirect) of the disposal facility, the ensuing situation will be considered by the competent authority at that time, and the relevant protection measures will be implemented. If a severe disturbing event occurs when there is no longer oversight of the disposal facility, there is no certainty that a competent authority will be able to understand the source of the exposure, and therefore it is not possible to consider with certainty the implementation of relevant measures to control the source. Inadvertent human intrusion into the geological disposal facility is not a relevant scenario during the period of direct or indirect oversight. In the period of no oversight, inadvertent human intrusion may occur and the consequences considered by the competent authorities at that time, if and when they understand the source of the exposure.
(h) For the design-basis evolution, the dosimetric criteria relevant to planned exposure situations are considered for assessing the safety and robustness of the disposal facility over the three main time frames. In the design stage, potential impacts of severe disturbing events may be estimated using stylised or simplified calculations. An indication of the robustness of the system could then be obtained by comparing these results with numerical values of dose or risk, if required. If this approach is adopted, the appropriate reference levels should be those for an existing exposure situation (a few mSv per year), or for an emergency exposure (in the range of 20– 100 mSv for the first year), depending on the specific scenario. If the event actually occurs in the future, the competent authority should apply the relevant protection criteria at the time.
(i) The safety case of a geological disposal facility, by including events of low probability and exposures to be delivered in the distant future, includes consideration of how to deal with potential exposures as defined by Publication 103 (ICRP, 2007).
(j) ICRP recommends that dose or risk estimates derived from these exposure assessments should not be regarded as direct measures of health effects beyond time scales of around several hundred years into the future. Rather, they represent indicators of the protection afforded by the geological disposal facility.
1 Risk is used in this document to mean ‘radiological risk’ as defined in Publication 103 (ICRP, 2007)
(k) Application of the three exposure situations and of dose limits, constraints, and reference levels as defined in Publication 103 (ICRP, 2007) during the three main time frames is indicated in Table A.
