The U.S. Nuclear Regulatory Commission (NRC) is amending its spent fuel storage regulations by revising the NAC International, Inc. MAGNASTOR[supreg] Storage System listing within the "List of approved spent fuel storage casks" to include Amendment No. 13 to Certificate of Compliance No. 1031. Amendment No. 13 revises the certificate of compliance to add a new type of radioactive contents to be stored inside the MAGNASTOR[supreg] transportable storage canister, add a new design configuration for the canister to accommodate the fuel bearing material and new canister components, and use an alternate compressive strength for concrete cask no. 6 of 6,000 psi.