Coordinated Research Project – T21028
Ageing Management Programmes for Spent Fuel Dry Storage Systems
The continued operation of a dry storage system and the ability to eventually retrieve and transport spent fuel is dependent upon being able to demonstrate that the safety of systems, structures and components (SSCs) are compliant with the safety justification. Since SSCs are subjected to degradation mechanisms and ageing processes, a sound knowledge of how these effect the operation of the dry storage systems is required.
With storage duration continuing to increase as a result of the lack of availability of reprocessing and disposal options, it is expected that the original licences will need to be renewed and/or the original design life of these systems will be exceeded.
The objective of this CRP is to develop guidance for preparing ageing management programmes (AMPs) for spent fuel dry storage systems considering implications of transportation after storage. The need for this CRP was identified as an outcome of the Working Group on Methodology for a Safety Case of a Dual Purpose Cask for Storage and Transportation of Spent Fuel. The scope of this CRP is not limited to DPCs but includes all spent fuel dry storage systems.
Background Situation Analysis:
Spent fuel dry storage systems cannot be managed in isolation. Thus there is a need to ensure continuity of licence for both storage and transportation; the duration of these licences may differ. For example, in some Member States the storage element of a spent fuel dry storage system may have been licensed for up to 40 years whilst the transport element may be subject to a 5 year renewal. In some cases the licence may be unlimited but, continued operation is subject to demonstrating compliance with an overall site licence.
As storage durations continue to increase as a result of the lack of availability of reprocessing and disposal routes it is expected that the original licences will need to be renewed and/or the original design life of these systems will be exceeded. In some Member States this situation has already arisen, and in others it is predicted that there will be this requirement. In such an event there is a requirement that a case be made that the safety functions can still be provided to enable continued operations and eventual fuel retrieval. As systems, structures and components (SSCs) used in spent fuel dry storage systems are subjected to degradation mechanisms and ageing processes that depend on the SSC, its operational and environmental conditions then a sound knowledge of how these evolve with time is required.
The coordinated research project is aimed at:
- Harvesting knowledge on the long term behaviour of SSCs used in spent fuel dry storage systems;
- R&D on materials used in spent fuel dry storage systems;
- R&D on inspection, monitoring and surveillance techniques for spent fuel dry storage systems;
- Tools for predicting the longevity of spent fuel dry storage systems;
- Ageing management programmes (AMP)/lessons learned;
- Learning from one another/gaining a consensus on the longevity of SSCs.
The ultimate goal will be to use this knowledge base as the first step in producing a generic ageing management programme which can be adapted to individual spent fuel dry storage systems/operating environment.
The need for this project was identified at a workshop held (May 2014) on the development and application of a safety case for dual purpose casks (DPC) for spent nuclear fuel with the aim of enhancing participants' understanding of the proposed concept of an integrated safety case for DPCs, to analyse the gap between the current practices within Member States and the proposed concept, and to discuss ways of further improving the application of this concept. One of the recommendations to the IAEA arising from this meeting was that it develops guidance for developing ageing management programmes (AMP) specifically for dual purpose casks; to include:
- Experience compendium
- Lessons learned, design changes towards inspection for ageing management;
- AMP for records management and ageing management for regulatory changes and technological advances;
- Maintenance of the safety case during the storage period.
A consultancy meeting held October 2014 to develop this CRP proposal considered that this requirement should not be limited to DPCs but should be expanded to all spent fuel dry storage systems.
The CRP is limited to dry storage systems used for power reactor spent fuel and specifically excludes studies on spent fuel integrity; which are addressed in other CRPs.
To develop the technical basis and methodology to enable guidance to be provided to Member States on how to generate an ageing management programme for spent fuel dry storage systems.
Specific Research Objective:
In the context of this CRP, research proposals are solicited which address one or more of the following topics:
- Ageing management plans in use for the dry storage system(s) in operation;
- Plans for development of an AMP for operators that will need an AMP for dry storage;
- Criteria for identifying the systems, structures, and components (SSCs) to ensure spent fuel dry storage systems are safe, and that spent fuel is transportable;
- Methodology for selection and examples of SSCs that are identified for inspection;
- Examples of maintenance and inspection on:
- Dry storage systems;
- transport casks (for on-site transport or off-site transport);
- A loaded cask system to qualify it for transportation (for on-site transport or off-site transport).
- Criteria and methodology to determine whether corrective action is required after inspection;
- Operational experience on degradation (ageing effects) on dry storage system components.
Expected Research Outputs:
The research outputs from the CRP will be published as a technical document titled "Ageing Management Programmes for Spent Fuel Dry Storage Systems".
Expected Research Outcomes:
- Sharing of information on operating experience related to dry storage systems;
- Methodology for creating ageing management programmes for spent fuel dry storage systems;
- Identification of key SSCs which need surveillance programmes;
- The substantiation of components which do not need to be monitored;
- Techniques for monitoring/inspecting key SSCs in spent fuel dry storage systems;
- Conditions to facilitate spent fuel retrieval/transportation;
- Identification of components considered susceptible to degradation with time.
Action Plan (Activities):
- Methodologies for developing an integrated ageing management plan;
- Lessons learned in spent fuel dry storage/developing AMPs;
- Techniques for monitoring and inspection dry storage systems;
- Methodologies for identifying SSCs;
- Methodologies for assessing the impact of deviations from normal operating conditions on SSCs;
- Mitigation/repair techniques;
- How collated data is used in either licence renewal processes or periodic safety reviews.
You can download the printable file here