1. Introduction
The International Atomic Energy Agency (IAEA) safeguards system has played important role to ensure that nuclear materials are used for peaceful purposes. Over decades, its inspection technologies have been refined primarily for large commercial Light Water Reactors (LWRs), characterized by solid fuels, relatively shorter refueling cycles, and physical accessibility.
However, the global rise of Small Modular Reactors (SMRs) introduces significant challenges to existing safeguards approaches. SMRs' modular designs, extended autonomous operation, and high-temperature environments necessitate an urgent reassessment of the applicability of current safeguards equipment.
2. Overview of IAEA Safeguards Technologies
The IAEA applies a multi-layered safeguards system consisting of nuclear material accountancy, non-destructive assay (NDA), containment and surveillance (C/S), environmental sampling, remote monitoring, and data security to nuclear power plants. NDA technologies, such as gamma spectroscopy and neutron counting, are used to confirm the presence and composition of nuclear materials. C/S techniques, including seals and surveillance cameras, maintain continuity of nuclear material monitoring. Environmental sampling detects traces of undeclared activities, while remote monitoring and cybersecurity measures ensure the integrity and confidentiality of transmitted data. These elements collectively support the IAEA safeguards verification mission.
3. Challenges for Applying Safeguards to SMRs
SMRs diverge significantly from conventional reactor designs, creating unique safeguards challenges.
Sodium-cooled fast reactors (SFRs) use liquid sodium as a coolant and conventional spent nuclear fuel pool cannot be used due to the risk of the explosion. It makes optical surveillance and sealing impractical. Additionally, the fast neutron spectrum undermines the performance of traditional neutron detectors, necessitating specialized devices.
High Temperature Gas-cooled Reactors (HTGRs) use TRISO-coated fuel, which greatly suppresses gamma and neutron emissions, complicating NDA measurements. The integration of fuel into graphite blocks and the extremely high operating temperatures demand equipment with enhanced thermal and radiation resistance.
Molten Salt Reactors (MSRs) circulate liquid fuel, making mass-based material accountancy nearly impossible. Moreover, the corrosive environment challenges the durability of seals, sampling systems, and surveillance devices.
Heat Pipe Reactors (HPRs) are sealed and operate autonomously for extended periods, limiting physical access to the core. Such designs often lack sufficient infrastructure for power and communication, necessitating safeguards measures implementation during the design phase.
Thus, SMRs introduce incompatibilities with traditional IAEA safeguards equipment due to differences in fuel form, coolant types, operational processes, and access limitations.
4. Evaluation Approach
The applicability of IAEA safeguards equipment to SMRs was assessed based on four criteria:
1) Technical Operation
The ability of equipment to function reliably in extreme environmental conditions.
2) Installation and Maintenance
Physical and infrastructural feasibility of installation and maintenance within SMR designs.
3) Data Verification
The reliability and auditability of data collected under altered operating conditions.
4) Regulatory Integration
The compatibility of safeguards equipment with national and international regulatory frameworks. This framework enabled a structured evaluation of the compatibility between current technologies and future SMR deployments.
5. Key Findings
This study finds that current safeguards equipment, designed for LWRs, cannot be easily applied to SMRs without significant adaptations. Optical surveillance and conventional sealing systems face fundamental barriers in opaque, sealed, or dynamically fueled reactors. NDA tools based on gamma and neutron detection encounter reliability issues due to suppressed emissions or complex material forms. Therefore, new safeguards technologies must be developed, including corrosion- and heat-resistant surveillance systems and robust remote monitoring infrastructures.
It is important to implement Safeguards-by-Design, whereby safeguards measures are integrated from the earliest design stages of SMRs. Reactor developers and IAEA must collaborate to ensure that inspections are feasible and effective without compromising operational goals. Given the limited access and long autonomous operating cycles of many SMRs, remote monitoring capabilities and strong cyber-security protections are indispensable. Furthermore, international harmonization of SMR safeguards protocols will be essential as deployment becomes global.
6. Conclusion
Small Modular Reactors represent a transformative shift in nuclear technology, but they simultaneously challenge the foundations of existing safeguards systems. This study highlights the significant technological gaps that exist and emphasizes the need for new, SMR-specific safeguards technologies and frameworks.
By prioritizing safeguards integration during reactor design, developing new inspection technologies, and enhancing international cooperation, the nuclear community can ensure that the emergence of SMRs does not undermine the integrity of global nuclear nonproliferation efforts.
