The Moon will be a primary target for human space exploration in the near future. A limiting factor
for a crewed mission to the Moon is the radiation dose during their stay on the lunar surface. While
the total dose is expected to be dominated by the galactic cosmic radiation, the potential occurrence
of large solar energetic particle events may lead to severe short-term effects and endanger the
success of the mission. This work investigated the expected dose rates for maximum galactic
cosmic radiation intensity and the total dose from several historical solar energetic particle events,
including the NASA reference event, through the application of numerical simulations with the
Geant4 Monte-Carlo framework. An evaluation of the shielding effect of lunar regolith was carried
out. For the solar particle events a shielding of more than 4 g/cm2 of regolith would reduce the
expected dose to below the current 30-day limits and a shielding of more than 10 g/cm2 would
result in a safety margin factor of two. For galactic cosmic radiation adding additional mass
shielding did not reduce the absorbed dose significantly. The estimated total dose equivalent
received utilizing around 180 g/cm2 of regolith amounted to 200 mSv/year, which is only about
25% below the corresponding estimates for an unshielded environment. The comparison to model
and experimental data from literature showed reasonable agreement to measurements but the
analysis of various earlier model results revealed, that substantial differences between the models
exist, despite all improvements that have been achieved in recent years.