Development of materials and fabrication of porous and pebble bed beryllium multipliers

Beryllium is considered to be a neutron multiplier material for the referen ce ITER breeding blanket. The main requirements for the porous beryllium mu ltiplier for the breeding blanket are: (1) inherently open porosity within 20+/-2% for easy removal of radioactive gases; (2) high thermal conductivit y; (3) close contact with a stainless steel (SS) shell to provide high heat transfer. A beryllium multiplier can be fabricated by two different techni ques: by manufacturing porous or pebble bed beryllium. The method designed (patent 2106931 RU) in SSC RF-VNIINM (Russia) provides for the production o f porous beryllium conforming to the requirements mentioned above. For comp arative fission tests and the optimization of breeding zone functional capa bilities, porous (21.9%) and binary pebble bed (density = 78%) beryllium mu ltipliers were fabricated. DEMO breeding blanket models and a mock-up of fi ssion (IVV-2M reactor) tests have been manufactured at SSC RF-VNIINM. (C) 2 000 Elsevier Science B.V. All rights reserved.