James Roll
Senior Manager, X-energy
Mechanical Engineering Department Lead for Xe-100 SMR Design
ASME Section III, Division 5 Expert
As Senior Manager and head of the Mechanical Engineering Department in the Reactors Division at X-energy, James D. Roll, P.E. leads multidisciplinary teams developing the innovative Xe-100 Small Modular Reactor (SMR). In this role, he directs engineering managers and their teams of mechanical engineers who provide specialized expertise across mechanical design, structural analysis, thermal hydraulics, and thermosystems engineering in the design of next-generation nuclear technology.
Mr. Roll's nuclear engineering career spans over 16 years, with expertise in conducting and managing reactor system component assessments, leading teams in advanced materials behavior analysis, and risk-informed and performance-based design. Prior to his current leadership position, he served as X-energy's Xe-100 Structural Analysis Manager & Structural Design Lead, where he managed structural analysis for the High Temperature Gas Reactor (HTGR) plant design and directed teams performing finite element analysis of core internal graphite structures using ANSYS according to ASME BPV Code Section III, Division 5 standards.
Mr. Roll actively contributes to industry by membership in codes and standards committees:
- Chair, Special Working Group on High Temperature Reactor Stakeholders (SWG-HTRS, ASME BPV III-5)
- Member, Working Group on Nonmetallic Design and Materials (WG-NMDM, ASME BPV III-5)
- Member, Sub-Group on High Temperature Reactors (SG-HTR, ASME BPV III-5)
- Member, Advanced Reactor Codes & Standards Collaborative (ARCSC)
Before joining X-energy, Mr. Roll spent over 12 years at Dominion Engineering, Inc., progressing from Associate Engineer to Senior Engineer. During this tenure, he led design, analysis, and deployment of complex mechanical structures for nuclear environments, supporting over 30 refueling outages across nuclear power plants in the U.S. and Spain. Mr. Roll's technical contributions at Dominion Engineering included calculating residual stresses in reactor piping dissimilar metal welds, evaluating vessel and piping stresses per ASME BPV Code Section III, using FEA to optimize reactor vessel head tensioning and detensioning sequences, and assessing transient creep and creep-fatigue crack growth rates to determine remaining life of thick-walled high temperature valves.
Mr. Roll holds a Master of Engineering and Bachelor of Science in Mechanical Engineering from Cornell University and is a Professional Engineer licensed in Virginia.