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Why should safeguards by design be a global effort?
Jeremy Whitlock
I can’t think of a more exciting time to be working in nuclear, with the diversity of advanced reactor development and increasing global support for nuclear in sustainable energy planning. But we can’t lose sight of the need to plan for efficient international safeguards at the same time.
Global nuclear deployment has been underpinned since 1970 by the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), making it a key customer requirement for governments to demonstrate unequivocally that the technology is not being misused for weapons development.
The International Atomic Energy Agency (IAEA) has helped verify this commitment for more than 50 years, but it has never safeguarded many of the advanced reactors (and related fuel cycle processes) being developed today.
Daniel Wooten, Jeffrey J. Powers
Nuclear Science and Engineering | Volume 191 | Number 3 | September 2018 | Pages 203-230
Critical Review | doi.org/10.1080/00295639.2018.1480182
Articles are hosted by Taylor and Francis Online.
Interest in circulating fuel reactors (CFRs), particularly molten salt reactors (MSRs) of the fluid fuel type, has been growing in the last two decades. Starting with a resurgence of interest in Europe, there have been a growing number of methods proposed and codes developed to model the kinetics of CFRs, which is a capability essential to the design and evaluation of such reactors. This work first reviews the physical phenomena unique to CFRs in light of current research and how CFR kinetics are impacted by these considerations. In general, it is found that the movement of delayed neutron precursors (DNPs) through the primary loop has significant impacts on transients at low reactor powers or those with significant spatial components such as a change in the primary loop mass flow rate. Effects on the neutron flux are exceedingly minimal and entirely negligible. An extensive review of published models and methods for simulating CFR kinetics is presented, along with transient simulations in fast and thermal neutron flux systems using representative codes from each of the main modeling categories. Comparisons among methods are presented as are recommendations for their use or nonuse in various transient and work-flow scenarios. In general, it is recommended that time-resolved, multigroup neutron diffusion approaches be used to establish ranges of applicability for point reactor kinetics (PRK)–based approaches that themselves may not be applicable for all modeling situations. In such cases, it is suggested that quasi-static approaches be used where PRK-based approaches cannot be used. Finally, a review of common assumptions used in these models is presented, along with an evaluation of their impact on model performance. It is found that neglecting turbulent diffusion in open core–type CFRs is a poor assumption that leads to an underestimation of the reduction of the delayed neutron fraction. Additionally, it is seen that exclusion of secondary heat transfer loops in models leads to underestimation of transient peaks and troughs.