Use of Safety Indicators in Waste Disposal

Coordinated Research Project (CRP) on The Use of Selected Safety Indicators (concentrations; fluxes) in the Assessment of Radioactive Waste Disposal

Introduction - A key requirement for development of a disposal system for radioactive wastes is that it should pose no significant long-term hazard to human health, and should cause no unacceptable harm to the environment. Safety indicators are the characteristics or consequences of a disposal system by which potential hazards or harm can be measured, and may be evaluated in the course of making a safety case for a disposal system. The role and utility of different types of safety indicators over different time-scales has been discussed in a previous IAEA publication TECDOC-767.

Objective

The objective of the CRP is to contribute, through the development of international consensus, to the assessment of the long-term safety of radioactive waste disposal by means of additional safety indicators based on the observation of natural systems. The main focus of the programme is expected to be on long-term safety aspects, including relevant safety criteria and assessment techniques and methodologies. The specific research outputs of the CRP are expected to be:

A a database of measured concentrations of target substances in different solid and aqueous materials, from different geographical areas, showing the spatial variability in these concentrations from the regional to the site scale
A database of estimated fluxes of the target substances (elements, radioactive isotopes and particular chemical compounds) between different subsurface and surface compartments, showing the spatial and numerical variations in natural fluxes from the regional to the site scale
An elaboration of the measured concentrations and estimated fluxes to construct 'measures' or 'ranges' that can be independently assessed to be safe and against which the outcomes of performance assessments can be evaluated
A TECDOC on the activities and findings of the CRP

Scope

The most widely used safety indicators for assessing the safety of radioactive waste disposal are Dose and Risk. Other safety indicators that may be used in addition to dose and risk are referred to as complementary safety indicators and the CRP investigates those indicators that could contribute to demonstration of safety. For the purposes of the present report, an indicator is taken to be any characteristic or consequence of a disposal system that has a bearing on the ability of the system to perform its safety functions. Indicators may be:

Directly measurable characteristics of the disposal system (e.g. radionuclide concentrations in groundwater at different locations and depths)
Characteristics derived from system understanding (e.g. container lifetimes and radionuclide fluxes across different boundaries in the disposal facility system)
Characteristics derived from calculations of the long term evolution of the disposal system (e.g. dose)

A distinction is also drawn between a performance indicator and a safety indicator. A performance indicator provides measures of performance to support the development of system understanding and to assess the quality, reliability or effectiveness of a disposal system as a whole or of particular aspects or components of a disposal system. A safety indicator, which may be regarded as a special type of performance indicator, is used to assess calculated performance in terms of overall safety.

Participants

Nine countries are participating in the CRP: Argentina, Brazil, China, Cuba, Czech Republic, Finland, Japan, Sweden and the United Kingdom.

Work Plan

Activities	Year
Formation of network of CRP participants	1999
1st Research Co-ordination Meeting to agree on general objectives, on contributions of individual participants and on co-ordination of activities	2000
2nd Research Co-ordination Meeting to reveiw results achieved, verify co-ordination and integration of activities and to agree on continuation of research work.	2001
3rd Research Co-ordination Meeting to review results achieved, evaluate proposed applications of the safety indicators and to agree on the production of CRP report.	2002
Publication of TECDOC containing the results of the CRP	2003

Documents

Safety Indicators in Different Time Frames for the Safety Assessment of Underground Radioactive Waste Repositories, First report of the INWAC Subgroup on Principles and Criteria for Radioactive Waste Disposal, IAEA-TECDOC-767 (1994). order a copy

Safety Indicators, Complementary to Dose and Risk for the Assessment of Radioactive Waste Disposal , IAEA-Working Material (1999). order a copy

CRP on the Use of Selected Safety Indicators in the Assessment of Radioactive Waste Disposal, First Progress Report for the Period April - October 2000, IAEA-Working Material (2001). order a copy

CRP on the Use of Selected Safety Indicators in the Assessment of Radioactive Waste Disposal, Second Progress Report for the Period November 2000 - July 2001, IAEA-Working Material (2001). order a copy

Safety indicators for the safety assessment of radioactive waste disposal, Sixth report of the Working Group on Principles and Criteria for Radioactive Waste Disposal, IAEA-TECDOC-1372 (2003).

Natural Safety Indicators for Use in relation to Radioactive Waste Disposal: Synthesis of CRP Results, IAEA-DRAFT-TECDOC-XXXX (2004)

For further information please contact K. Hioki