R&D ON MATERIALS FOR NEW CONTAINERS OF LL/IL/ML NUCLEAR WASTES

According to the line 3 of 91-1381 law voted on December 30, 1991 by the french Parliament, CEA is investigating long-term storage for nuclear wastes. Within this frame, to complete packaging facilities already available, we develop a new high integrity canister characterized by: • aptitude to accept all wastes types without or with limited pre-treatment and characterization • confinement performances for long term storage and retrieval possibility • flexibility for waste packaging after long-term storage • manufacturing at acceptable cost. A problem of paramount importance is the material choice for inner part directly in contact with waste. This work thus focuses on studying materials allowing to securely and durably confine a large set of primary wastes. In addition to classical materials like stainless steel, two complementary potential solutions have been identified, when combining severe specifications and economical constraints, which could fit with different and complementary wastes families: either a low cost steel protected by an enamel coating, or a polymer material such as High Density Poly Ethylene. We present in this work the specific R&D activities performed on these two classes of materials. Concerning the first class, the brittle behaviour of enamel is investigated by different mechanical tests such as scratch test and impact test, in order to qualify its potential handling during filling operations before storage. Its chemical resistance in acid and alkaline media is also estimated by means of accelerated high temperature corrosion tests. In the second case, the main research concerns the polymer ageing phenomena under the all possible effects and more specially radiochemical and thermo chemical ones. This simultaneously leads to: • a large radiological inventory of the various considered wastes, • the analysis of literature data completed with specific irradiation campaigns on selected PE families, • the experimental returns already available on polymers aged in similar media, such ones used in nuclear facilities or interim storages. At the present stage of the work, no critical “stop point” has been detected for the two container material solutions explored. WM’01 Conference, Febrary 25-March 1, 2001, Tucson, AZ