ASME Codes Support Small Modular Reactor Development and Use: Unique Designs Require a Robust Code

Abstract

Authors: Sargent & Lundy, LLC: Delfo Bianchini, Dennis Demoss and William Peebles. Focus: Operations, Applications & Components. This paper will review new Small Modular Reactor (SMR) designs and implications on the ASME Section III Code. Four SMR technologies will be discussed: B&W mPower (TVA Clinch River site), Westinghouse SMR (Ameren Callaway site), NuScale/Fluor SMR (Pacific NW lab site) and Holtec SMR (Savannah River site). SMR reactor designs vary from 45 to approximately 225 MWe. SMR goals include significantly reducing plant capital cost requirements and enabling multi-reactor module construction and addition over time providing greater utility flexibility. A primary SMR advantage includes its installation in smaller grids typical of electrical power systems in developing countries. Unique aspects of the SMR technologies include integral reactor and steam generator vessel, integral pressurizer and internal piping, below grade containment vessel, helical-coil integral steam generators, integral decay heat removal systems, modular plant construction and arrangement, in-service inspection unique requirements, special materials and welding. Current ASME code design rules and requirements may require expansion and clarification; Section XI testing requirements and frequencies may require revision.