Background

Lead-bismuth eutectic (LBE) is a very effective nuclear coolant because of its low melting temperature, high boiling temperature and neutronic transparency. In addition, LBE itself is a very efficient spallation target for neutron generation via a high-energy proton accelerator. On the other hand, liquid metal corrosion and embrittlement are major issues that must be dealt with in using LBE as a nuclear coolant and spallation target. Thus, LBE continues to be the subject of considerable research in the United States, Europe and Asia, specifically within the framework of the accelerator-driven transmutation systems and fast-spectrum reactors. An expert group that addresses the major issues associated with the use of LBE as a nuclear coolant in a unified framework is of benefit to all the interested parties. The main deliverable of the expert group was the LBE handbook.

Objectives

The objectives of the expert group were to:

• monitor the feedback from version 0 of the LBE handbook
• collect, analyse and check the consistency of expected new results from ongoing HLM related programmes
• update the handbook and release version 1.

Scope

A number of HLM experiments were underway in Europe, such as the EUROTRANS project (devoted to the study of high-level nuclear waste transmutation with sub-critical accelerator-driven systems) and the ELSY project (devoted to the development of an HLM-cooled critical transmutation system). Moreover, additional experimental results were expected from laboratories in Japan, the United States and Korea. These new experimental results were crucial to consolidate:

• knowledge of the basic properties of HLM
• assessment of structural materials in HLM and neutron, neutron/proton fields
• basic thermal-hydraulics experiments underway to the means to qualify numerical methods and physical models for the thermal-hydraulics assessment of critical and sub-critical HLM-cooled reactors.
• technological advancement of HLM components such as chemistry control systems, heat exchangers and also operational as well as measurement techniques.

Finally, the successful completion of the MEGAPIE experiment would deliver unique results on materials behaviour in HLM and representative conditions of a high power neutron spallation target. Consolidation of the understanding of HLM properties, the materials and thermal-hydraulics assessment, as well as the technological advancement, will be an essential contribution to the development of selected Gen-IV fast reactors and radioactive waste transmuters.