Status of beryllium development for fusion applications

Abstract

Beryllium is a leading candidate material for the neutron multiplier of tritium breeding blankets and the plasma facing component of first wall and divertor systems. Depending on the application, the fabrication methods proposed include hot-pressing, hot-isostatic-pressing, cold isostatic pressing/sintering, rotary electrode processing and plasma spraying. Product forms include blocks, tubes, pebbles, tiles and coatings. While, in general, beryllium is not a leading structural material candidate, its mechanical performance, as well its performance with regard to sputtering, heat transport, tritium retention/release, helium-induced swelling and chemical compatibility, is an important consideration in first-wall/blanket design.Differential expansion within the beryllium causes internal stresses which may result in cracking, thereby affecting the heat transport and barrier performance of the material. Overall deformation can result in loading of neighboring structural material. Thus, in assessing the performance of beryllium for fusion applications, it is important to have a good database in all of these performance areas, as well as a set of properties correlations and models for the purpose of interpolation/extrapolation.In this current work, the range of anticipated fusion operating conditions is reviewed. The thermal, mechanical, chemical compatibility, tritium retention/ release, and helium retention/swelling databases are then reviewed for fabrication methods and fusion operating conditions of interest. Properties correlations and uncertainty ranges are also discussed. In the case of the more complex phenomena of tritium retention/release and helium-induced swelling, fundamental mechanisms and models are reviewed in more detail. Areas in which additional data are needed are highlighted, along with some trends which suggest ways of optimizing the performance of beryllium for fusion applications. DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Assessment of database for interaction of tritium with ITER plasma facing materials

“…Increasing porosity facilitates tritium release and may reduce swelling, but is poor for thermal performance and ductility. (Billone 1993) Ross and Terreault (1 990) implanted deuterons into 99.5% pure, hot-rolled, polished Be specimens, used elastic recoil detection to determine the deuteron ranges and variances, and fit an equation of the form R = Ro E". The BABOUM code predictions were fairly close to these results, but the TRIM code and the Anderson-Ziegler compilation yielded ranges that were much too short.…”

Atomic, Crystal, Elastic, Thermal, Nuclear, and Other Properties of Beryllium

“…6 Small levels of impurities and displacement damage have little effect on thermal conductivity. 11 However, the presence of as-fabricated porosity and/or helium bubbles can cause a large reduction in the effective thermal conductivity. The following expression is claimed to be a relatively good fit to data of both vacuum-hot-pressed and foam (low-density) beryllium for porosities up to 50%:…”

“…The principal isotopes of beryllium that have been identified are: 6 Be, 7 Be, 8 Be, 9 Be, and 10 Be. 5 Additional isotopes listed are: 11 Be, 12 Be, and 14 Be. 28 Some properties of the principal beryllium isotopes are listed in Table II-4-1 and II-4-2.…”