There is increased interest among the Member States to introduce advanced fuels and extend the discharge burn up of fuel assemblies in PHWRs for better resource utilization and improved economics. Higher burn up and advanced fuels pose new challenges to fuel design and manufacturing techniques, and may require new cladding materials. Fuel reliability issues include release of gaseous and volatile fission products, pellet-clad interaction, build-up of internal pressure, fuel swelling, degradation of thermo-physical properties of fuel, cladding corrosion and stress corrosion cracking, etc. Attention is also required for the performance of fuels under off-normal and accident conditions. Similar issues have been addressed for LWR fuel and fuel assemblies. PHWR fuel characteristics are quite different from LWR fuel characteristics with respect to clad thickness, high linear power, high centre line temperature, absence of plenum volume, on-line re-fuelling, etc., which affect fuel performance. This CRP is intended to encourage the development and sharing of work on resolving the above challenges.
To encourage the development and sharing of research work on resolving the challenges in deploying advanced fuels for extended burnup and for enhanced operational margin in PHWRs.
(1) Fuel concepts for higher burnup (design, materials and fabrication)
(2) Life limiting aspects of extended burnup
(3) Fuel concepts leading to enhanced operational margins
Higher burnup and enhanced operational margin in PHWRs are important research targets for national programmes for PHWR fuel in all participating Member States. The CRP results are found to be consistent with such national programmes, and provide desirable directions with technical basis for further deployment of advanced fuels for higher burnup and for enhanced operational margin in PHWRs. Exchange of experimental data conducted under this CRP will enable Member States to save a significant effort in performing similar activities.
The objectives and output of this CRP are in line with the technical contents of the Agency programme (project 33, subproject 1.2.2.001 Nuclear Power Reactor Fuel Engineering and Operation). This CRP was supported by the Technical Working Group on Fuel Performance Technology (TWG-FPT), the advisory experts working group of the Department of Nuclear Energy on nuclear fuel design, fabrication and in-reactor performance issues.