Interest in Generation IV nuclear reactors has led to increased interest in molten salt reactors (MSRs), which were included in the classification, beyond their use only in Nuclear Weapons States. As Anna Armstrong, a nuclear engineering graduate student working in the Center for Nuclear Security Science and Policy Initiatives (NSSPI), explained, MSRs are “unique from a nuclear safeguards perspective compared to traditional reactors.” Armstrong worked with NSSPI Director Dr. Sunil Chirayath to investigate safeguards complications that arise with MSRs.
“Current international safeguards under the IAEA safeguards scheme,” according to Armstrong, “focus on item counting for nuclear reactors and bulk nuclear material accountancy (NMA) for the front and back end of the nuclear fuel cycle. Given that an MSR is essentially a reactor and a fuel cycle in a single, bulk special nuclear material (SNM) handling facility, the current IAEA safeguards scheme cannot be applied.”
Moreover, some small, low-power-generation MSR designs fall within the small modular reactor classification, which makes them attractive from a proliferation standpoint. Their modular nature allows for configurations of MSRs to be combined at a single reactor site, which, said Armstrong, “poses a greater proliferation challenge.” For this reason, MSR safeguards are an emerging challenge, particularly in Non-Nuclear Weapon States. Armstrong’s research proposes a method for safeguarding a theoretical MSR design to prevent proliferation.
Armstrong’s study involved radiation transport modeling and fuel burnup simulations of a thermal neutron spectrum MSR using both the SCALE and Monte Carlo N-Particle (MCNP) codes. She performed this modeling and simulation to compute the inventory of SNM production and flow rates in MSRs to support the development of nuclear safeguards approaches for MSRs. Ultimately this study tested the applicability of hybrid K-edge densitometry (HKED) for MSR safeguards. HKED could be used to determine isotopic concentrations at strategic points in the system to support implementation of material balance areas (MBAs) used to determine if any SNM is unaccounted for.
“NSSPI students have many unique opportunities to enrich their graduate study experience,” Armstrong reflected about her experience as a NSSPI student. “I was able to work as a research intern in the International Safeguards Group at Oak Ridge National Laboratory (ORNL). While at ORNL, I learned from experts on topics associated with my research, such as: international safeguards, nonproliferation, and molten salt reactors. I learned further about IAEA safeguards as well as emerging safeguards strategies and technologies for MSRs. I was also able to visit and learn about one of the few domestic HKED measurement facilities, which was a great experience.”
In addition to her internship experience, Armstrong also had the opportunity to participate in technical seminars and tours as part of a nuclear nonproliferation workshop. Another rewarding NSSPI experience she had was the opportunity to serve as the Executive Vice President of the Texas A&M University Institute of Nuclear Materials Management (INMM) Student Chapter.
Said Armstrong, “I am very proud to continue the tradition of our INMM Chapter, especially given that NSSPI established the first student chapter of INMM. The learning and professional development I gained during INMM Chapter and NSSPI All-Hands Meetings was very valuable to me as a graduate student. These extracurricular activities make NSSPI unique within the Nuclear Engineering Department.”
Armstrong successfully defended her thesis and is graduating in May 2021 with a Master of Science in Nuclear Engineering, a Graduate Certificate in Nuclear Security, and a Certificate in Advanced International Affairs from the Bush School of Government and Public Service. Armstrong was selected as a National Nuclear Security Administration (NNSA) Graduate Fellow for the Class of 2021. She will begin her fellowship in the NNSA Office of Nuclear Incident Response (NA-84) upon graduation.
Before joining NSSPI, Armstrong received a Bachelor of Science in Nuclear Engineering with a minor in Radiological Health Engineering from Texas A&M University. She also interned with the late Senator Daniel Inouye of Hawaii on Capitol Hill and with the United States Secret Service in Washington D.C. where she accompanied Special Agents on Head of State and U.S. President protective missions and served on the Critical Infrastructure Committee Cyber Security Sector during the 2013 Presidential Inauguration National Special Security Event (NSSE).