Monte Carlo nuclear well logging benchmark problems with preliminary intercomparison results

Preliminary results on three nuclear well logging benchmark problems previously posed are given for the general purpose Monte Carlo codes MCNP and McBEND and the specific purpose Monte Carlo codes McDNL, McPNL, McLDL, and MCNL. These benchmark problems are for compensated neutron porosity, neutron lifetime, and the γ-ray lithology-density well logging tools. Results indicate general agreement among the codes used with only two minor discrepancies in the last problem. For future use these three benchmark problems have been slightly modified according to suggestions made by Mills et al. (1991) and an additional general benchmark problem has been proposed for determining the thermal and epithermal neutron fluxes at two different radii within a homogeneous sphere surrounding a point, isotropic 14-MeV neutron source.