Security
About
The Security criterion evaluates how reactor design choices influence risks related to reactor facilities, personnel, and nuclear materials. Security considerations are central to responsible reactor design selection because they shape regulatory confidence, international acceptability, and the conditions under which projects can be licensed, financed, and deployed. This criterion assumes that the IAEA will safeguard all eligible reactors once deployed; it does not speak to whether a specific design can be safeguarded.
Rather than assessing specific threat environments or operational security performance, this criterion’s indicators focus on inherent design features that affect security across contexts. Together, the indicators provide a structured basis for comparing how reactor designs differ in material sensitivity, fuel-cycle implications, and design-level security integration.
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Indicator Breakdown
Weight 40%
Fuel
Core question
What is the enrichment level and composition of the reactor fuel?
The Fuel indicator measures the enrichment level and material composition of the reactor’s nuclear fuel. This indicator captures the material attractiveness for a nuclear explosive device, handling requirements, and implications for material control and accountability. This indicator also captures the extent to which reactors of this type contribute to the global economy for weapons-usable nuclear material.
The Fuel indicator assigns each fuel a weight relative to the security risk it poses. Reactors using standard-assay LEU receive the highest value; HALEU is assigned 70% of the LEU value, reflecting the need for stricter security and handling requirements relative to standard assay LEU, while still posing significantly lower proliferation risk than plutonium-bearing fuels. Plutonium-bearing fuels are treated as a distinct category and receive the lowest score within the Fuel indicator. In addition, any reactor that uses Plutonium-based fuel receives a 50% reduction to its overall Security score. This approach reflects the fact that plutonium is directly weapons-usable, and therefore presents a fundamentally higher level of security risk across deployment scenarios.
Coding rules
- 1 — Plutonium-based fuel, thorium-based fuel, highly enriched uranium-based fuel, or reprocessed fuel
- 2 — Enriched uranium fuel above 10%
- 3 — Enriched uranium fuel below 10%
Weight 40%
Nuclear Material Production
Core question
What is the potential for the reactor to produce weapons-usable nuclear material?
The Nuclear Material Production indicator measures the reactor’s potential to produce weapons-usable nuclear material by taking into account its fuel cycle, burnup rates, neutron spectrum and the presence of fertile material. This indicator also captures whether the reactor has online reprocessing.
Coding rules
- 1 — Any reactor with integrated reprocessing
- 2 — Fast neutron spectrum with fertile blanket
- 3 — Fast neutron spectrum without fertile blanket; or heavy water reactor
- 4 — Thermal neutron spectrum (except heavy water reactors) without integrated reprocessing
Weight 20%
Security by Design
Core question
Has the reactor developer built in security by design?
The Security by Design indicator captures whether physical security and cybersecurity are embedded in layout, refueling cadence, access control, and system architecture from the earliest design stages. This could include below-grade siting, welded cores, limited and controlled access points, protected vital areas, and design features that support containment and surveillance or delayed access.
Coding rules
- 0 — No
- 1 — Yes
