MARVEL: a digital computer code for transient analysis of a multiloop PWR system

The MARVEL (Multi-Loop Analysis of Pressurized Water Reactor System Transient) digital computer code was developed to calculate multiloop detailed transient behavior of pressurized water reactor systems. The program simulates two reactor coolant loops including two steam generators and associated systems. It also simulates reactor kinetics, reactor control and protection system, safeguards system, and other subsystems. The code can also be used for three- or four-loop plants by assuming that the other loops are operated in the same way as either of the two loops. The program can be utilized as a tool for various types of accident analyses and control studies, including startup of an inactive reactor coolant loop, loss of reactor coolant flow, reactivity insertion incidents, steam line break accident, steam generator tube rupture accident, and others.