In the framework of the joint international efforts to reduce the risk of proliferation by minimising the use of highly enriched uranium, a new research reactor fuel based on uranium-molybdenum (UMo) alloys is being developed by the HERACLES group. HERACLES is composed of...
In the framework of the joint international efforts to reduce the risk of proliferation by minimising the use of highly enriched uranium, a new research reactor fuel based on uranium-molybdenum (UMo) alloys is being developed by the HERACLES group. HERACLES is composed of AREVA-CERVA, CEA, ILL, SCKâ€¢CEN and TUM, all organisations with a long-standing history in fuel manufacturing and qualification. HERACLES works towards the qualification of UMo fuels, based on a series of â€œcomprehensionâ€ experiments and manufacturing developments.
There are two types of UMo fuel fine particles dispersed in an Al matrix, and monolithic foils. The qualification phase of these fuels is scheduled to begin in 2019; the project HERACLES-CP will prepare the way with an initial comprehension phase, to improve our understanding of the fuelsâ€™ irradiation behaviour and consequent the manufacturing/industrialisation process. One of the key components in the project is the SEMPER FIDELIS irradiation test, which aims at investigating the fuel swelling phenomenon and the effects of coating, with a view to arriving at procedures for fuel engineering.
The challenges as regards manufacture lie in the basic elements of both fuel typesâ€™ production process and plate manufacturing. For the dispersed fuel, this includes the pin casting for the rotating electrode process and the atomization process itself. For the monolithic fuel, this concerns the development of coating for the foils. All these components are essential to prepare the fuel qualification phase. The general objective of this project can therefore be summarized as: The provision of the technical and scientific foundations for the successful qualification of UMo fuel.
High-performance research reactors are at the start of the supply chain for medical isotopes like 99Mo. Successful conversion to lower enriched and where possible LEU fuel is therefore a key element in the mitigation of the risks surrounding the supply of isotopes as demanded by NFRP 8. Yet, the role of the HPRRs is far broader, as they are providing scientific and engineering solutions to questions of high societal importance.
The governing objective of HERACLES-CP is to lay the technical and scientific foundations for the successful qualification of UMo fuel. In this regard, the following progress has already been made:
â€¢ Irradiation experiments:
- The irradiation matrix for the SEMPER FIDELIS irradiation experiment has been defined. Together with EMPIrE, the experiment will close most of the remaining knowledge gaps. Fabrication for EMPIrE has been completed and started for SEMPER FIDELIS.
- Ion experiments showed no accelerated growth of the interdiffusion layer between UMo and Al in the first days of an irradiation.
- The UMo electrode casting and powder atomization process have been studied in detail and the understanding of both processes was greatly improved. It is now safe to start construction of the pilot fabrication equipment.
- Development of the pilot induction casting furnace has begun, drawings have been finalized.
- Modelling of UMo dispersion plate fabrication by rolling has been started.
- PVD-Coating of monolithic foils and the subsequent processing into plates (C2TWP) has been developed from inert material over DU to specification-conform LEU in less than 14 month.
â€¢ Measurement technology:
- The PERSEUS channel gap measurement device prototype has been completed, first experiments have been performed in the ILL reactor.
- All communication plans and media have been developed and set up.
- A Uranium transport study has been conducted to ensure that all transports within the HERACLES development program can be carried out.
HERACLES-CP has enabled the consortium to advance the state of the art in many aspects:
â€¢ For the design of the SEMPER FIDELIS irradiation matrix, dozens of experts from the EU and the US have (re-)measured, collected and evaluated data from more than one dozen prior irradiation experiments to ensure that SEMPER FIDELIS will deliver the maximum relevant information for the further development of UMo. Once SEMPER FIDLIS and its sister experiment EMPIrE are completed, the understanding of UMo irradiation behaviour will reach a new level.
â€¢ The technique of UMo powder atomization is now understood to an extent that enables the consortium to build the next stage of manufacturing equipment on the pilot level. The construction of the pilot induction furnace has already begun.
â€¢ Monolithic UMo foils can now be coated with PVD and turned into plates with a very high yield. The technology for this is fully available in Europe.
â€¢ The PERSEUS measurement device is a unique tool for measuring the thickness of fuel plates in-pile. Once it is advanced and qualified for an actual material test reactor, it will enable high quality inter-cycle inspections during test irradiations of plate-type fuel.
More info: http://www.heracles-consortium.eu/cp.php.