Bengt Åkesson

Wp-cave - a new concept for underground high-level nuclear waste repository

© 1981 Pergamon Press Ltd Published by Elsevier Ltd All rights reserved. An almost spherical rock cavern is surrounded at some distance by a fairly thick clay barrier. Nuclear waste canisters are mounted in cylindrical holes traversing large concrete balls. These are stored in the cavern together with similar concrete balls (without canisters) filling up the entire cavern space. The clay barrier prevents ground water circulation for a very long time, enhances ion-exchange, and increases the repository resistance against future tectonic movements and earthquakes. Calculations of heat balance, thermal effects, clay barrier function and costs have been performed. One repository (Fig. 1) accommodates one years unreprocessed waste from 12 nuclear 1000 MWe reactors assuming 10 years of interim storage. Construction operations are outlined. Various advantages of the concept are emphasized (see list at end of paper).

Reduction of Wind-Induced Random Vibrations by Use of an Optimal Dynamic Absorber

The efficiency and stability of a dynamic vibration absorber in reducing wind-induced random vibrations of a structure will be investigated. The mean of the peak values of a critical stress resultant (design force) will be minimized by attaching an optimally tuned and damped linear absorber to the structure. The primary structure is modelled as a lightly-damped one-degree-of-freedom linear system. The influence of the inherent damping (not very well known in practice) of the primary structure on the choice of optimal absorber parameters and on the final response is found to be small. Alternative objective functions are studied. In a typical example, an absorber mass equal to one percent of the vibrating mass of the primary structure is found to reduce the mean of the peak values of the stress resultant by one third.