SNUPPS is an acronym standing for Standardized Nuclear Unit Power Plant System. It refers to a 4-loop PWR reactor design produced by Westinghouse in the 1970s. The design was developed for four USA utilities, and plants were built at Callaway and Wolf Creek. The UK plant at Sizewell B was also based on SNUPPS but with significant modifications, such as a passive Emergency Boration System. Further reading Chapter 5: The Nuclear Industry's Experience with Standardization, Nuclear Powerplant Standardization: Light Water Reactors, April 1981, Congressional Office of Technology Assessment, NTIS order #PB81-213589 Pressurized water reactors