1. To request MACCS, WinMACCS, SecPop, and/or MelMACCS, go to
  2. Scroll to the MELCOR/MACCS heading and select the Non-Disclosure Agreement (NDA) link.
  3. Fill out the NDA form and submit it via fax/email to 301-251-7423 or Submitting a completed NDA acts as the first step to request the software.
  4. An email will be sent to you once the NDA has been approved by the NRC.
  5. Additional internal licensing steps much be taken after the NDA is approved. These items can take several weeks to complete.
  6. When licensing approval is completed, you will receive a temporary login ID and validation document. Once you have completed the validation step, a one-time password is displayed.
  7. Go to and enter your assigned Login ID and Password and follow all subsequent steps to download the code.
  8. After downloading the software, you will be prompted to request an installation key from Dr. Nathan Bixler ( to finalize the process.