Active handling experiment with neutron sources (AHE). Final report

The objective of the Active Handling Experiment with Neutron Soruces was to investigated radiological aspects due to backscattered neutrons when spent fuel and high level waste will be handled in the drifts of an underground repository located in a salt dome. As neutrons play an important role in the direct disposal option, main emphasis was laid on their contribution to the total dose equivalent rate. The radiological exposure caused by direct neutrons and neutrons scattered by the salt rock during handling processes of POLLUX packages and transfer packages was simulated and experimentally analysed with the help of the AHE package. The AHE shielding cask was filled with one Cf-252 line source in order to simulate the neutron fields of a loaded POLLUX cask and a transfer cask loaded with a fuel element canister with respect to neutron energy distributions and local dose equivalent rates. The results of the AHE experiment provided valuable contributions for a better understanding of radiological aspects during handling spent fuel/high level waste in an underground repository. Validated computer codes are available now which make it possible to minimize the occupational dose. (orig.)