4.19.4.1 General Considerations

A comprehensive, although not recent, review of the science and technology of beryllium can be found in Beryllium Science and Technology.120

Several reviews have been published recently related to use of beryllium in tokamaks and the status of the investigations of the Be properties for the fusion application.3’121-126 Various production and proces­sing methods of beryllium metal fabrication have been reviewed in Dombrowski.127 The majority of methods are based on powder metallurgy and include powder preparation from cast product by grinding (i. e., attrition milling, impact grinding, ball mill grinding); further powder consolidation (i. e., by cold pressing (CP), cold isostatic pressing (CIP), vacuum hot pressing (VHP), hot isostatic pressing (HIP)); and possible additional mechanical treatment (e. g., extru­sion, rolling, forging). Beryllium protective armor can also be produced by plasma spray (see Section 4.19.4.3) and vapor deposition.

Several proposals were made at the beginning of the ITER Research Programme during the ITER Engineering Design Phase to develop a fusion grade beryllium with high ductility, high resistance to heat flux, and high radiation resistance. However, it was recognized that this development would require sig­nificant efforts and could not be supported only by requests from the fusion community.

There are various beryllium grades, which have been developed for different applications. These grades differ by chemical composition (BeO content, impuri­ties), by method of powder preparation, by method of consolidation, etc. The nonexhaustive list of various beryllium grades from the US and the Russian Feder­ation is presented in ITER Materials Properties Handbook (MPH).12 Grades with similar composi­tion are under production in Kazakhstan and in China.

We briefly discuss below some of the most relevant physical and mechanical properties of beryllium, in relation to its application as armor for PFCs.