IAEAInternational Atomic Energy Agency

International Workshop onthe Safe Disposal of

Low Level Radioactive Waste

WG3 debriefing

IAEA

Radiation protection principles and safety concepts• For communicating the SA results, some countries use dose constraints,

others risk limits. • When communicating with stakeholders, need to explain the robustness of the

overall concept:• results of the SA assessment• safety concepts used (BAT, DID, optimisation) to make the overall concept safe• feedback and experience gained over the last 50 years all around the world• how uncertainties are taken into account

Topic 1 – Development of disposal concept

IAEA

Waste characterisation• Need for proper waste characterisation in order to avoid hot spots in the DF

(human intrusion scenarios)• National waste classifications differs in many countries. IAEA’s waste

classification followed but not strictly. • Verifications about WP content• Difficulties for characterising the waste:

• Many radionuclides difficult to measure• Accuracy of the measurements?• Validity of the detection limit used?• Adequacy of the scaling factors used?

• Assessment of radiological, chemical and biological hazards all included in the SC? Reviewed by a single regulatory body or by several distinct entities?

• Relevance of carrying out destructive tests: some countries use them, others prefer not to because of the extra waste generated

Topic 1 – Development of disposal concept

IAEA

Topic 1 – Development of disposal concept

Feedback from design/operation• General tendency to overestimate the operational dose for workers (margins) • Importance of the quality management system (example of operation incident

due to improper waste characterization)• Possibility to improve the design after some years of operation feedback• New IAEA document in preparation aiming at gathering international feedback

on design and operation

Site characterisation• Site selection process:

• based on guidance criteria or imposed by context (because of proximity to NPP, of stakeholders acceptance, ...)

This will influence the level of characterization needed to demonstrate the safety of the disposal concept

• The disposal concept needs to be flexible enough to take into account new site issues that may arise during the construction/operation phases

IAEA

Topic 4 – Post-closure aspects

Memory preservation• Many examples of memory loss during the operational life of a facility!• Passing on individual people’s memory to others... Importance of the

management system and its regular testing (audits)• Need for discussions (IAEA guidance?) about what to include in a facility’s

archival system to be kept and potentially used during the active institutional control period

• OECD/NEA RK&M project giving many insights about ways to preserve memory over very long time scales

IAEA

Topic 4 – Post-closure aspects

Institutional control & license termination• When to consider that a license can be terminated? • Active vs passive IC. Who will be responsible for the passive IC? • 300 years is very long why not have the state also responsible (in addition to

the operator) for preventing access to the site?• If DF owned and operated by private companies

sufficient state oversight? Impact on long term financial management?

IAEA

Topic 4 – Post-closure aspects

Retrievability• By definition, a disposal facility is with no intention to retrieve the waste.

In some countries, the retrievability concept was introduced to answer the stakeholder’s concern.

This can lead to a decrease in the safety of the disposal facility. • Need for robustness of the barriers conditions (WP and the engineered barriers)

• Retrievability option restricted to the operational period? Even after closure?

Level of effort needed to retrieve the waste (ICRP 122)• Dose evaluation of the retrievability measures (operational retrieval actions vs

long term radiological impact if no retrieval)

Remediation• Definition in the context of disposal facilities?

Environmental remediation of the site (i.e. aquifer decontamination) vs real remediation of the whole site?