Yes, a nuclear modelling software called MCNP is widely used and written entirely in fortran. Some of its source code can date back to the dawn of computing in

Yes, a nuclear modelling software called MCNP is widely used and written entirely in fortran. Some of its source code can date back to the dawn of computing in the 1940s! Edit to say I missed your newer project specification; MCNP is still under very active development and frequent updates, if that counts.