Experiments on Neutron Leakage Currents and Moderator Storage Times of Various Spallation Target–Moderator–Reflector Assemblies

Abstract

Results from spallation neutron source mock-up experiments on neutron leakage currents and storage times of ambient temperature as well as cryogenic moderators are presented. The experiments were carried out in support of high power sources like the German SNQ and the European ESS. The vast amount of work performed elsewhere will not be treated in this review. Lead, tungsten and depleted uranium targets were bombarded with protons and deuterons with energies between 400 MeV and 1.1 GeV. Beryllium, graphite, lead and D₂O reflectors, as well as polyethylene and H₂O pre-moderators around the liquid hydrogen moderators, were employed. The results for the time average leakage currents from both ambient and cold moderators are compared to those from the high flux reactor at the ILL in Grenoble. From the results on moderator storage times, the peak neutron leakage currents for pulsed operation of various target/moderator/reflector assemblies as a function of the proton pulse duration have been deduced.