Will RMP*Comp be updated? If so, would I have to redo calculations I might already have made with an earlier version?

No, you do not have to redo your work if you have already completed your consequence analyses. RMP*Comp is based on the EPA's Offsite Consequence Analysis Guidance (OCA Guidance), which is an "evergreen" rather than a final document; it can be updated as new information or better modeling techniques become available. 1) You are not required to redo your consequence analyses every time there is a change to the Guidance. 2) However, as you develop your analyses, be sure to use either the latest version of RMP*Comp or the latest edition of the Guidance. As changes are made to the Guidance, we'll update RMP*Comp. The changes will automatically be available in both the browser-based version, and in the downloaded version. (When the downloaded program starts, it checks for, and applies, any updates.)