The need to perform large-scale molecular dynamics simulations of radiation defects in ferritic steels has stimulated the recent development of a 'magnetic' interatomic potential for body-centred cubic alpha-iron [1,2]. Here we describe the first application of the new method to molecular dynamics modelling of radiation defects. We investigate the magneto-elastic fields of defects and study their thermally activated migration. We propose that the origin of the low-temperature (T <= 120 K) resistivity recovery stages in irradiated alpha-iron is associated with clustering of self-interstitial atoms. (c) 2007 Elsevier B.V. All rights reserved.