SMR Safety & Manufacturing: How Passive Design Enables Factory Production

Why removing thousands of active components makes nuclear reactors manufacturable for the first time—and how shipbuilding expertise is already producing reactor modules

When Doosan Enerbility began manufacturing NuScale reactor pressure vessel components at their Changwon facility in 2022, they discovered something remarkable: the same precision forging techniques used for conventional power plants could achieve nuclear-grade quality control—but only because NuScale's passive safety design eliminated the complex active systems that made traditional reactor manufacturing so challenging.

The numbers tell the story: traditional nuclear plants require thousands of active safety components including pumps, valves, diesel generators, and control systems. NuScale's design eliminates 99% of these components, relying instead on physics-based passive safety systems that operate without external power, pumps, or human intervention. This simplification enables factory manufacturing for the first time in nuclear power history.

The result is a manufacturing revolution that's already producing hardware. Doosan has manufactured components for 12 NuScale modules totaling over 2,000 tons, while BWXT Canada expanded their facility with $80 million specifically for SMR production. These aren't future projections—they're current manufacturing operations that demonstrate how passive safety systems unlock factory production economics.

Yesterday we examined the SMR market opportunity and engineering workforce implications. Today, let's explore the technical innovations that make SMR manufacturing possible and the industry partnerships that are already producing reactor components at scale.

The Traditional Nuclear Manufacturing Problem

Why Active Safety Systems Killed Factory Production

Traditional nuclear power plants represent manufacturing nightmares precisely because their active safety systems require extensive on-site integration and testing. The complexity that provides safety in large reactors makes factory production economically impossible.

Active Safety System Complexity:

• Emergency Core Cooling: Multiple pumps, heat exchangers, accumulator tanks, and control systems

• Containment Systems: Spray systems, air filtration, hydrogen recombiners, and fan coolers

• Backup Power: Diesel generators, electrical switchgear, fuel systems, and battery banks

• Control Systems: Thousands of sensors, actuators, control panels, and communication networks

Traditional Manufacturing Challenges:

• Component Count: 50,000+ major components requiring individual testing and integration

• Field Assembly: Most safety systems must be assembled and tested on-site

• Custom Integration: Each plant requires unique system configurations and interfaces

• Quality Control: Nuclear-grade welding and assembly in outdoor construction environments

Vogtle Units 3&4 Example: The AP1000 design, despite being "simplified," still requires extensive active safety systems:

• 4 Emergency Diesel Generators: Each with 6,000 gallon fuel tanks and support systems

• 4 Component Cooling Water Pumps: With heat exchangers and piping networks

• 8 Safety Injection Pumps: Plus accumulators, piping, and control systems

• Complex Control Room: 18,000 indication points and 3,000 control functions

This complexity drove construction costs to $35 billion and extended timelines to 7+ years, demonstrating why active safety systems prevent factory manufacturing.

The Physics-Based Solution

Small Modular Reactors solve the manufacturing problem by replacing active safety systems with passive systems that operate through fundamental physics principles rather than mechanical components.

Passive Safety Principles:

• Natural Circulation: Gravity-driven coolant flow eliminates pumps and external power

• Decay Heat Removal: Heat conduction and radiation eliminate mechanical heat exchangers

• Containment Cooling: Ambient air cooling eliminates fans and power systems

• Reactor Shutdown: Gravity-driven control rod insertion eliminates complex mechanisms

NuScale's Passive Safety Revolution

Technical Specifications and Performance

NuScale's 77 MWe reactor module demonstrates how passive safety enables manufacturing simplicity while exceeding traditional nuclear safety performance.

Core Passive Safety Systems:

Emergency Core Cooling System (ECCS):

• Operation: Two-phase natural circulation without pumps or external power

• Performance: Maintains core cooling for 30+ days without makeup water

• Mechanism: Vaporized coolant exits through reactor vent valves, condenses in containment, returns via gravity-driven recirculation

• Capacity: 263-711 kg/s primary flow rates sufficient for all heat removal requirements

Decay Heat Removal System (DHRS):

• Operation: Natural circulation through steam generators and condensers submerged in reactor pool

• Performance: Removes 100% of decay heat without operator action

• Mechanism: Steam generator tubes transfer heat to reactor pool, which rejects heat to atmosphere