This paper presents a verification and validation (V&V) study of the Monte Carlo neutron transport code MCS for the criticality analysis of LWR fuel in transportation and storage casks/packages. A total of 173 critical experiments from the NUREG/CR-6361 report are analyzed with MCS and the ENDF/B-VII.1 cross section library. A preliminary verification is conducted by comparing the reaction rates. Subsequently, a criticality analysis of the 173 benchmarks is performed. The average value of the multiplication factors calculated by MCS for the 173 critical experiments is 1.00243 with a standard deviation of 291 pcm and extremum error values of -1451 pcm and +1661 pcm compared to the experimental results. The bias of the package (MCS + ENDF/B-VII.1 library) for the criticality analysis of LWR fuel transportation/storage casks is, therefore, estimated to be +243 pcm. This paper demonstrates the capability of the MCS code to perform the criticality analysis of LWR fuel transportation and storage packages. (C) 2020 Elsevier Ltd. All rights reserved.