The design of high intesnity spallation sources, like the European Spallation
Source (ESS) with a proton beam energy of 1334 MeV and a beam power of 5MW,
or the Austrian project AUSTRON with a prton beam energy of 1600 MeV and a
beam power of 500 kW (short pulsed, 10 Hz), require best possible estiamtes
for the biological shield and for the layout of the target-reflector-moderator
complex. The use of Monte Carlo simulation techniques in general, and now
in shielding design requires the development of numerical strategies to
make accessive use of variance reduction techniques in order to get the
best possible balance between computing time and accuracy of results.
At the moment the research concentrates on the development of computational
strategies to improve the design of the biological shield fro such high
intensity spallation sources. A further step towards an even more demanding
problem is in preparation: Simulation of ground- and skyshine effects at
the position of an instrument.