Index > 5 Stewardship >

5.1 Introduction

General guidance on and an introduction to stewardship are presented in Section 2.10. The aim of Section 5 is to present more detailed guidance on stewardship [IAEA-2006c]: e.g., when to implement, what plans/actions should be carried out, etc.

After remediation has been completed, the degree, extent and duration of control, if any, ranging from monitoring and surveillance to restriction of access, should be reviewed and formalised with due consideration of the residual risk [IAEA-2003]. The organisation responsible for the surveillance and verification of activities should be clearly identified.
In the case of long term remedial actions, long term stewardship may start when the remedy is shown to be functioning properly and operating as designed. Large, complex sites may undergo remediation of portions of the site while other parts may continue to perform mission-related work. As a result, specific actions that would normally be associated with long term stewardship, such as monitoring the effectiveness of engineered controls, may start years before final closure of the site.

There are several possible end points for the remediation process [IAEA-2007a]:

  1. Unristricted use of the area. Before a site may be released for unrestricted use, a survey should be performed to demonstrate that the end point conditions have been met (see Section 3.3.10.7). If the chosen remediation process involved the removal of contamination, and if the site meets the required remediation end criteria, it may be released without further restrictions. In this situation, the prevailing conditions should be considered to be the residual background conditions for a new practice or for use of the site for habitation [IAEA-2007a]:
    For example, for the remediation of the site for any new practice, the contribution to individual doses from an eventual remediation of the new practice should not exceed an additional dose of 300 μSv/year over the new background level that resulted from any previous remediation activities following any previous practices (See Figure 2.4 in Section 2.2.2.5). However, the sum of all possible combinations of doses to members of the public due to exposures from all subsequent practices should not exceed an additional dose of 1 mSv/year over the original background level before the first practice started.
    Further, consideration should be given that even after free release a site may become the source of contamination, hence:
    “Consideration should be given to the potential circulation of material coming from future modification of the buildings, including demolition after site release. Materials originating from the site, after the site is released from regulatory control, need to comply with the national requirements for radiation protection… This should be an integral part of the optimization analysis of the clean-up process. Scenarios for exposure to sites released for unrestricted use should be realistic and consider the potential uses of the materials from the released site” [IAEA-2006a].
  2. Restrictued use of the area. The term ‘restricted use’ means that some types of use will be allowed while others will not; for example, in certain cases the use of a site for forestry may be possible but its use for agriculture may be prohibited [IAEA-2007a]. Where a significant part of the exposure due to residual contamination may arise from the food chain, the use of agricultural countermeasures should be considered. Similarly, the use of a site for recreational, industrial or certain agricultural purposes may be appropriate, but its residential use may not be. Impacts of the residual contamination on aquifers should also be considered in this evaluation.
    In cases where all reasonable remediation options are insufficiently protective or in cases where the optimised remediation options do not include the removal of the contamination, specific restrictions on the future uses of a contaminated site may be imposed. Specific restrictions may also be established for controlling the removal of material from such sites or the use of such material.
    An appropriate programme, including any necessary provisions for monitoring and surveillance, should be established to verify the long-term effectiveness of the remedial measures, and should be continued until it is no longer necessary [IAEA-2003].
    A mechanism should be established for periodically reviewing the conditions in remediated areas and amending or removing any restrictions imposed. If surveillance and maintenance are required after remediation is completed, a surveillance and maintenance plan should be prepared which should be periodically reviewed. The plan should be subject to the approval of the competent authority.
    Interested parties (e.g., stakeholders, etc.) should be informed of any restrictions and of the results of all monitoring and surveillance programmes, and should be invited to participate in decision making after the remediation.
  3. Restricted access to the area. Access to the area may need to be restricted and measures may need to be put into place to enforce this.
    Restriction of access to contaminated sites and/or institutional control may be required to be maintained in cases of serious residual contamination [IAEA-2007a]. Specific restrictions should be established for the following purposes [IAEA-2003]:
    • To control the removal of radioactive material from contaminated sites or the use of such material, including its use in commodities;
    • To control access to contaminated sites;
    • To control the future uses of contaminated sites, including use for the production of foodstuffs and water use, and to control the consumption of foodstuffs from contaminated sites.
      The degree of any such restrictions should be determined by the competent authority. In case institutional control is seen to be necessary, post remedial activities should occur in a controlled context and may include [IAEA-1999]:
    • Monitoring the long term stability and performance of barriers which isolate or contain residual radioactively contaminated materials; depending on the type and levels of residual contamination, access control measures may vary from the placing of warning signs to fencing of various types and guarded control stations; site control personnel should have the legal authority to deny access to the site, if required;
    • Monitoring environmental indicators within and down gradient of the remediated site;
    • Maintenance of barriers and other protection systems;
    • Prevention of intrusion;
    • Adherence to licensing conditions that may have been imposed;
    • Regulation and administration of administrative controls;
    • Assembly, distribution, and safekeeping of all project and post-remediation period data;
    • Analyses and records.

In each case, further surveillance and monitoring may be required to confirm the long term effectiveness of a performed programme of remediation, and additional controls may need to be imposed on the basis of the monitoring results.
The degree, extent and duration of control, if any, ranging from monitoring and surveillance to restriction of access, should be reviewed and formalised with due consideration of the residual risk at the remediated site.
So, long term stewardship results from the need to address the reality that ‘clean-up’ of facilities can not in all cases achieve conditions deemed acceptable for unrestricted use and will therefore require some form of management far into the future.

5.1.1 Assessment criteria for establishing short term or long term stewardship

Long term stewardship results from the need to address the reality that ‘clean-up’ of facilities can not in all cases achieve conditions deemed acceptable for unrestricted use and will therefore require some form of management far into the future.

Principal drivers for needing long term stewardship at a site may be a combination of:

  • Priorities; Owner, local, federal priorities may not support funding for clean-up to free-release levels.
  • Long-lived contaminants; Radionuclides, chemicals, and metals may not be easily or quickly broken down to safe constituents.
  • Lack of technology; No further environmental benefit from remediation may be attainable with existing technology or asymptotic levels have been reached, e.g., groundwater and vadose zone.
  • Risk; Short term human health or environmental risks of conducting remedial activities may outweigh the benefits of remediation.

The technical needs for dealing with long term stewardship may be identified as discussed in the following paragraphs.

5.1.2 Scope and objective of long-term stewardship

While removal of radioactively contaminated soil and groundwater is obviously a permanent solution for the site in question itself, the chosen disposal site may have to be subject to a stewardship programme. Any engineered solution to contain contaminants or to reduce exposures, whether on-site or at the chosen disposal facility, will only have a limited period of useful life. Natural forces will gradually degrade structures such as liners, barriers or cappings. Modelling predictions, based on historical experience and observed parameter values, allow an estimate to be made of how long an engineered near surface structure is likely to perform according to intentions. However, experience in recent times with floodwater defences has shown that our events database extending some 100 years into the past may be insufficient to capture the whole parameter range required for, say, a 1000 year lifetime. This uncertainty over the long term effectiveness of remediation solutions requires provisions for monitoring, periodic performance assessment, and, if required, maintenance; hence the establishment of a stewardship programme. It is this uncertainty that creates the need for long term stewardship. While making remediation decisions, it is important to consider long term stewardship issues and obligations explicitly when comparing remedial alternatives and implementing a final remedy [DOE-1999].

Stewardship, and by inference the steward’s responsibilities, must be defined at a practical implementing level, that is from the bottom up. For stewardship to be understandable and affordable, a narrow definition of stewardship is recommendable [KLEINRATH].
Stewardship plans cannot be static but have to be adapted to the development of a site, with respect to both its physical state and its use. Periodic revision of the stewardship plans will be necessary.
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Figure 5.1 Stewardship challenges
Figure 5.1 Stewardship challenges

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The objectives of long term stewardship should be to ensure adequately long-lived institutional controls, monitoring, engineering controls, maintenance activities and information management for the related radioactively contaminated sites and/or groundwater, and surveillance to restriction of access to the site.

Plans dealing with these topics should be proposed by the operator of the site on the basis of a graded approach and in consideration with ‘the components of stewardship’ (see Section 5.2). The restrictions proposed by the operator should be enforceable by the regulatory body and the clean-up/remediation plan should specify which entity will ensure that the proposed restrictions are maintained.

The societal aspects of long term stewardship may present several important challenges, such as building trust, communicating the nature of the risks and of the remediation and stewardship options, reconciling economic, management and technical issues with considerations of public values and beliefs, resolving ethical questions and engaging stakeholders in the decision making process, and thereafter retaining stakeholder commitment.

Many regulations assign authority and responsibility for environmental contamination into the foreseeable future, i.e., decades, but residual contamination at facilities or sites may remain hazardous for a very long time.

5.1.3 Life cycle management and stewardship

In recent years a slow change in paradigms has occurred: awakening awareness of long term ecological problems has led to a move away from treating environmental problems only after they have occurred. The goal is to avoid environmental impacts from the beginning in the life cycle of a human activity. This life cycle management aims to treat each stage in the life of a facility or site not as an isolated event but as one phase in its overall life. Thus, the planning does not only cover each stage but is also a continuing activity, taking into account actual and projected developments. As a consequence, a more forward looking integrated management of human activities was introduced into the legislation in many countries.

5.1.4 Regulatory framework

The objectives and outcomes of remedial actions have a direct and lasting effect on the level of long term stewardship required at a site. The International Commission on Radiological Protection (ICRP) stipulates that:

‘Remediation measures shall be justified by means of a decision aiding process requiring a positive balance of all relevant attributes relating to the contamination. In addition to the avertable annual doses, both individual and collective, other relevant attributes shall be assessed’ [ICRP-1990].

The prime objectives for remediation actions are the abatement of environmental impacts and the reduction of risks to human and other receptors. According to [IAEA-2003]:

‘Remediation shall (a) reduce the doses to individuals or groups of individuals being exposed; (b) avert doses to individuals or groups of individuals that are likely to arise in the future; © prevent and reduce environmental impacts from the radionuclides present in the contaminated area’.

The criteria for the release of sites from regulatory control upon the termination of practices have been formulated recently in an IAEA Safety Guide [IAEA-2006a], see Section 2.5. Though strictly speaking this guide applies only to the decommissioning of authorized practices, sites where past practices or accidents have led to contamination in the ground would have to comply with most of the criteria set out there. The preferred option, according to this IAEA Safety Guide, is unrestricted release provided the site meets the appropriate release criteria developed for a reasonable set of possible future uses (see also Section 5.2.10.5).

In the case of restricted use:

‘The restrictions should be designed and implemented to provide reasonable assurance of compliance with the dose constraint for as long as they are necessary… Therefore, existing regulatory limits on the institutional control time frames should be taken into consideration in deciding whether to release a site for restricted use’.

The scope of a stewardship program is outlined implicitly in Section 5.1.2, while the actual regulatory framework will vary from country to country. Even after free release, a site may become the source of contamination, hence:

‘Consideration should be given to the potential circulation of material coming from future modification of the buildings, including demolition after site release. Materials originating from the site, after the site is released from regulatory control, need to comply with the national requirements for radiation protection … This should be an integral part of the optimization analysis of the remediation process. Scenarios for exposure to sites released for unrestricted use should be realistic and consider the potential uses of the materials from the released site’ (see Section 2.5 and [IAEA-2006a]).