Mcnp Software Quality: Then and Now

MCNP is the Monte Carlo N-Particle radiation transport code whose history dates back more than half a century to the early days of computing. From a simple beginning, its uses have grown to include fields such as criticality safety, radiation shielding, oil well logging, and medical imaging and diagnostics and an international user community of over 3000 users. This large user community could only happen by the maintainance of sofware quality throughout its history. This paper will describe how the quality was maintained in the past, how the process is being improved today, and directions for future efforts.