Safety-related Issues for the Disposal of Intermediate Level Waste (ILW) Dr. Jürgen Wollrath Federal Office for Radiation Protection (BfS) Department Safety of Nuclear Waste Management 09 September 2013, IAEA TM on ILW Disposal Vienna/A

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Content Report on the Outcome of the Consultants‘ Meeting to Draft a Technical Document on Disposal Facilities for Intermediate Level Waste, April 2013, Vienna/A, - Part 3 - ―Disposal Facility Design Operational issues Considerations for long-term isolation ―Safety Assessment Time scales Radionuclide migration Institutional control and human intrusion ―Waste Acceptance Criteria Waste packaging Acceptance criteria

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Disposal Facility Design – Operational Issues ―ILW contains a larger variety of waste types compared to HLW ILW may contain operational as well as decommissioning waste there is a higher possibility to standardise operational waste than decommissioning waste the large variety of waste types needs to consider various issues that are not associated with HLW (i.e. chemical interactions) ―ILW may also contain large components (i.e. pumps, steam generators – if classified as ILW –, pipes) these large components may create additional operatioal issues, both logistically (i.e. ramp instead of shaft) and radiologically (protection of workers) time of delivery may be forced by the waste producer  may need interim storage capacity

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Design Considerations for Long-term Isolation ―Purpose: provide containment and isolation of the radionuclides in the waste from the biosphere ―Multi-barrier concept should form the foundation of the design considerations ―Design considerations are typically not different to other types of disposal facilities, i.e. Geological Disposal Facilities for Radioactive Waste (IAEA Safety Guide SSG-14) ―Containment period of the waste packages is dependent on the activity and on the content of long-lived waste

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Safety Assessment – Time Scales ―Regardless of the type of waste and the repository depth, the safety case has to define an appropriate assessment time-scale ―The assessment time-scale must be consistent with the natural evolution of the site the considered depth of the disposal facility the characteristics of the waste (activity, half-life) ―A reasonable margin is to be taken into account between the scientific capacity to predict the evolution of the site and the time-scale of the safety case ―At the end of the assessment time-scale one has to take into account loss of containment and potential dispersion of the waste; therefore the acceptable content of long-lived radionuclides is a function of the acceptable time-scale an assessment time-scale of about 1,000,000 years (as often applied for HLW) requires disposal in a deep geological formation the assessment time-scale for near-surface disposal facilities is in the order of a few 100 years an assessment time-scale between 10,000 and 100,000 years (that may be appropriate for ILW) may result in disposal at shallower depth compared to deep geological disposal

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Safety Assessment – RN Migration ―The required performance concerning radionuclide migration can be graded to the activity level of the waste ―The capability of the disposal facility to isolated the waste from the biosphere should not be related to the depth of the disposal facility itself but to depth related properties of the geosphere including impermeability to water dissolution capacity leach rate and solubility retention of radionuclides retardation of radionuclide migration

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Safety Assessment – Institutional Control and HI ―The maximum duration of the institutional control period should be equal to or less than the maximum duration of the societal capability to control the land use with time (typically a few 100 years) ―IAEA Safety Requirement SSR-5 indicates for near-surface disposal facilities an institutional control period of several tens to hundreds of years following closure; IAEA safety standards do not impose any minimum duration for geological disposal ―Regardless of the type of waste and the depth of the disposal facility the safety case cannot rely on institutional control periods longer than a few 100 years ―Human intrusion scenarios must be considered in the safety case after the end of the institutional control period ―The type of human intrusion scenarios is depth dependent ―The deeper the disposal facility is located the lower is the likelihood of human intrusion ―Due to its limited duration institutional control has an influence only on the initial amount of short-lived radionuclides; the acceptable content of long-lived radionuclides is a function of the type of human intrusion scenario to be considered and therefore a function of the repository depth

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Waste Acceptance Criteria – Waste Packaging ―Most of intermediate level waste streams need to be appropriately conditioned and packaged for storage, transportation and disposal ―The type of waste packages for ILW is primarily selected for transportation, handling and operational purposes ―Nevertheless, the resistance of waste packages to degradation is one of the principal characteristics of the waste package; therefore it may become of concern for long-term safety considerations ―Along with their containment capability waste packages should be designed with respect to the mechanical and chemical compatibility with the other components of the natural and engineered containment system of the disposal facility

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Waste Acceptance Criteria ―As with any other disposal facility, the establishment of waste acceptance criteria is essential to ensure the continued validity of the safety case; any changes of waste acceptance criteria will need to keep in mind the boundaries of the safety case ―When developing waste acceptance criteria, it is important to recognise the large variety and complexity of intermediate level waste ―SSG-14 (para. 6.38) identifies some issues to consider: permissible range of chemical and physical properties of the waste and the waste form permissible dimensions, weight and other manufacturing specifications of each waste package allowable levels of radioactivity in each package allowable amounts of fissile material in each waste package allowable surface dose rate and surface contamination allowable decay heat generation for each waste package requirements for accompanying documentation

IAEA TM ― Technical Meeting on the Disposal of Intermediate Level Waste, September Thank You