Speaker
Description
In the United States (U.S.), a risk-informed package approval process has been developed to address the regulatory challenges of safely transporting microreactors that may contain irradiated nuclear fuel. Regulatory approval of such a transportation package based on quantitative risk information would be groundbreaking and could help pave the way for general use of microreactors in both commercial and defense applications. Previous work demonstrates the viability of a risk-informed regulatory approach developed by a Pacific Northwest National Laboratory (PNNL) led team for domestic highway transport of a U.S. Department of Defense microreactor design.
The implementation of this risk-informed approach was endorsed by the U.S. Nuclear Regulatory Commission (NRC) as an acceptable way to seek microreactor transportation package approval. Given that possible uses include multiple modes of transport (e.g., highway, maritime, rail and barge), that study is being taken a step further in a second study by demonstrating its viability for maritime transport. A draft report of the study has been submitted to the U.S. NRC for review. Unlike the first, the second study addresses international implications, since maritime transport may involve routes through international waters as well as the territorial waters and ports of other countries.
In the first study, the risk informed approach developed for domestic highway transport was based almost entirely on U.S., nuclear regulations, guidance and applications. In the second study, an evaluation was performed to investigate whether the risk-informed approach aligns with international maritime agreements and the nuclear regulations and expectations of other countries. This alignment is expected to be successful given the deliberate international harmonization of regulations on radioactive material packaging and the consistency of risk-informed application metrics across U.S. and foreign regulations. Beyond regulatory alignment, applying this approach also has important implications for transport security, particularly given the potential attractiveness of microreactor fuel to threat actors.
This paper takes a preliminary look at how applying this risk-informed regulatory approach could affect the security of transporting microreactors that may contain irradiated fuel. It’s notable that many microreactor designs will be fueled with uranium oxycarbide (UCO) tri-structural isotropic (TRISO) particles containing high-assay low-enriched uranium (HALEU). This higher assay fuel could raise the attractiveness of the transported microreactor fuel as a target for threat actors.
The preliminary assessment of the potential impact on security of the use of this risk-informed regulatory approach to safety contrasts two approaches: transporting the nuclear fuel in a microreactor package that relies primarily on the robustness of the reactor vessel and integral shielding as containment and transporting fuel in traditional Type B thick-walled steel casks. The assessment considers transport security measures applied to the vessel itself, including tamper-indicating devices, tracking systems, intrusion detection, locks, barriers, and other delay measures. Besides physical security, the preliminary assessment looks at procedural measures such as use of an escort ship, communication capability, and the use of security personnel. Perhaps of special interest is the concept of compensatory measures allowed under Title 10 of the U.S. Code of Federal Regulations, which parallel the IAEA’s transport provisions known as “special arrangements.” These measures must be assessed for their interface with transportation security. For example, compensatory measures might require an escort ship to help avoid collisions with other vessels or obstacles, a requirement that may also need to be integrated with the security-related escort provisions.
The purpose of this paper is to describe the viability and international relevance of a risk-informed regulatory approach to package approval for maritime transportation of microreactor packages that could contain irradiated fuel in terms of safety and security.
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