The full MACCS Code Suite includes MACCS, WinMACCS, MelMACCS, SecPop, AniMACCS, and MACCS/HYSPLIT Tools.

Approved code users can obtain software through their account on the MACCS download site. MACCS and WinMACCS come together as a single installation file. The other software components are available as separate installations. All software components work on Windows, and a Linux version of MACCS is also available.

New code users should submit a software request following the instructions below. Software requests for the "MACCS Code Suite" provides access to the full suite of MACCS codes, except for requests from foreign organizations that do not normally receive SecPop. SecPop works with US census information and is not designed to support other parts of the world.

Software requests for "MACCS/WinMACCS," "MelMACCS," or "SecPop" provides only partial access to the MACCS Code Suite. In the past, we required separate requests for each. Users that may have submitted a single request only for the MACCS code can submit a new request for the "MACCS Code Suite" to obtain full access.

Access to AniMACCS and MACCS/HYSPLIT Tools comes automatically with any request that includes MACCS v4. Upgrades to MACCS v4 are available to eligible users of previous MACCS versions and do not require a new formal software request.


Code distribution depends on the organization you are affiliated with.

Foreign Organizations:

  • Foreign organizations must either be a member of the Cooperative Severe Accident Research Program (CSARP), or they must have the approval of the CSARP member in their country. You can contact if you have questions regarding CSARP membership.

U.S. Domestic Organizations:

  • Most domestic organizations are eligible to receive MACCS codes. Please complete the non-disclosure agreement (NDA) form and submit your request to determine your eligibility.


Foreign Organizations:

  • MACCS software is included with the annual CSARP membership. The code fees are waived for CSARP members and organizations they approve.

U.S. Domestic Organizations:

  • Code fees are waived for employees of the US government and their contractors, and university staff and students.
  • One-time code fees for domestic private entities (including commercial and non-governmental organizations) are as follows:
    • MACCS v4: $4,000 (a discounted rate of $1500 applies if you previously paid for MACCS v3)
    • MelMACCS: $1,000
    • SecPop: $1,000


New Software Requests:

  1. To request the MACCS Code Suite*, first submit a completed non-disclosure agreement (NDA).
    • Download a blank NDA form and fill it out.
      • In the field for the code name, enter "MACCS Code Suite".
      • The signature on page 2 is for someone signing on behalf of your organization, usually a team leader / manager / department chair / professor.
      • The signature(s) on page 4-5 are for code users. The signature on page 2 and 4 can be the same person, if appropriate.
      • The NDA has space for up to 7 users. If you would like more, please complete a second NDA.
    • Submit the completed NDA to When the NRC approves your NDA, the NRC will send you and Sandia an email. Sandia will begin their licensing process, which may take several weeks to complete.
  2. Sandia will contact you to collect fees (if applicable) and ask you to sign a limited use access agreement (if applicable). Submit these to Sandia.
  3. Code users listed on pages 4-5 of the NDA will receive Sandia download accounts. Go to the download site and enter your email and the provided password to access the software downloads.

* If you are only interested in "MACCS," "MelMACCS," and/or "SecPop," enter the applicable code names. Access to WinMACCS, AniMACCS, and MACCS/HYSPLIT Tools comes automatically with MACCS v4.

Adding New Users:
To add new users within your organization, please complete a new NDA form containing the new user information and submit it to, using the same process discussed above. Please do not submit addendums or alterations to previous NDAs.

Upgrading to MACCS v4:
A new NDA is not necessary. Send an email to and stating your request. Sandia will contact you to collect fees (if applicable) and notify you when you receive access to MACCS v4 on your Sandia download account.