CONCENTRATIONS OF RADIOLOGICALLY IMPORTANT TRAMP ELEMENTS IN STANDARD-GRADE STAINLESS STEELS WITH PARTICULAR RELEVANCE TO ACTIVATION OF THE FIRST WALL OF NET
The dose equivalent rate of activated components determines the optimum time for decommissioning and the procedures to be adopted for the management of radioactive structural wastes from nuclear reactors. In standard-grade stainless steels the elements cobalt, nickel, niobium, molybdenum, silver and possibly some rare earth metals are the only ones likely to contribute appreciably to the gamma dose rate at a cooling time around 100y. Up to about 80y after shutdown, 60Co generated from iron, nickel and cobalt dominates the dose rate, whilst at longer times 94Nb from niobium and molybdenum and 108mAg, from silver present as an impurity, usually become dominant. Activation calculations have been performed for the irradiation regime anticipated for the first wall of the Next European Torus, in order to determine the concentration limits on cobalt, niobium and silver in a type 316L steel such that these potential impurity elements do not appreciably enhance the overall dose rate of the steel. A review of existing information on the impurity contents of stainless steels indicates that it should not be difficult to attain the required limits in a nuclear-grade 316L steel.
Bibliographic Reference: REPORT: CLM-R293 EN (1989) AVAILABLE FROM THE LIBRARIAN, UKAEA, CULHAM LABORATORY, ABINGDON, OXON. OX14 3DB (GB)
Record Number: 1989128048100 / Last updated on: 1990-11-09
Available languages: en