Monte-Carlo simulations of the new LNHB manganese bath facility

► We modeled the new LNHB manganese bath using MCNPX, GEANT4 and FLUKA. ► ENDFBVII.0 cross sections library with thermal scattering choice is discussed. ► Discrepancies between codes are studied and causes are pointed out. ► New experimental process for accuracy assessment of the codes is described. ► New inputs to the uncertainty budget of the manganese bath method.