The Fukushima Daiichi accident (March 2011) resulted in severe damage and reported fuel core meltdown in three of the reactors on the nuclear power plant site. A fourth reactor, although shutdown, suffered severe damage to its structure from a hydrogen explosion, which resulted in plant and roofing materials being deposited in the fuel storage pool. The fuel in this pool may also have been damaged due to loss of cooling water and the introduction of seawater as a replacement. In terms of multiple failures, an accident of this scale has not been experienced previously resulting in a substantial remediation challenge. The objective of this CRP is to expand the existing knowledge base and identify optimal approaches for managing severely damaged spent fuel. Severely damaged spent fuel covers: material from post-irradiation examination; fuel debris, fuel damaged during fuel handling operations; fuel damaged as a result of loss of cooling; corium; molten core– concrete interaction products.
To expand the existing knowledge base and identify optimal approaches for managing severely damaged spent fuel. Severely damaged spent fuel covers: Material from post irradiation examination; fuel debris; fuel damaged during fuel handling operations; fuel damaged as a result of loss of cooling; corium and melted core concrete interaction products (MCCI).
To report and assess the characterization of severely damaged spent fuel
To report development work on and assess the techniques for the in situ characterization and monitoring of severely damaged spent fuel
To report, assess and potentially develop methods to mitigate adverse changes in the long-term behaviour of severely damaged spent fuel and packaged material (for example radiolysis, chemical and physical properties)
One of the main benefits of the CRP was the creation of a network of experts working in a very singular field. They could transfer knowledge and establish a very fruitful international collaboration, e.g.:
- Efforts of EAEA (Egypt) in modelling accident progression, an exercise informed through dialogue with JAEA;
- Cooperation between KRI (Russia) and JAPAN or between KRI (Russia) and EU/JRC Karlsruhe on corium samples handling and characterization.
The CRP also created a guidance to catalogue samples, including advice on:
- The data needed on samples, storage and preservation,
- Sampling plans,
- Samples characterization through analytical techniques,
- Sharing logistics.
The CRP was framed at the end of the IAEA Action Plan on Nuclear Safety, to address issues related to Spent Fuel Management.
The CRP was a unique and relevant source of information compiling many aspects of severe power reactor accidents, with a loss of cooling, resulting in the formation of corium and products from molten corium-concrete interaction (MCCI).
The CRP provided learning opportunities on the characterization of corium and MCCI products.
The CRP also provided information and experiences on the management of severely damaged spent fuel from NPPs and fuel debris.