Neutronic Design of the Bunker Shielding for the European Spallation Source

The European Spallation Source bunker is a common shielding area that surrounds the target monolith, protecting the instrument areas from the high dose of ionizing radiation that accompanies the spallation reaction. A comprehensive neutronic work was performed, which took into account dose rates outside the bunker wall and roof, skyshine and activation. A wall with a thickness of 3.5 m and a stepped roof with a thickness of 1–1.5 m, both made of heavy concrete with a density of 3.8 g/cm3, were recognized as the best solution that satisfies the radioprotection requirements for the operation of the facility.