Request Code

At this time requests to download MACCS, WinMACCS, SecPOP, or MelMACCS can be made from  This will take you to a Nuclear Regulatory Commission's (NRC) webpage which provides additional detail on obtaining MACCS, WinMACCS, SecPOP, MELMACCS, and other NRC-Developed Computer Codes.  Scroll down to the MELCOR/MACCS heading and click on the non-disclosure agreement (NDA) link.  This will open a NDA form which must be filled out before you can download the codes.  Select the code you wish to obtain from the drop-down menu on the form and complete and fax/email the form to 301-251-7423 or  A fee may be necessary to obtain the code depending on what type of organization is requesting the code.  Once the NRC obtains and approved the NDA they will send you a Login ID and Password.  Once obtaining the Login ID and Password, go to the MELCOR download website (  Enter your assigned Login ID and Password and follow all subsequent steps to download the code.