Engineered Safety Features

The SMR-160+ incorporates multiple levels of defense-in-depth to remove heat from the reactor and assure safety. All safety systems are located inside the robust Containment Enclosure Structure, rendering them secure and safe from external threats, both natural and man-made. The systems are simpler than current operating reactors, eliminating active pumps from the safety functions, thus making them more reliable. No operator actions are required to place and maintain the reactor in a safe shutdown condition, making it “walk away safe”. All makeup water needed for a postulated loss of coolant accident is inside containment, thus making the containment fully isolable, eliminating dose to the public and effects on the environment from this event.

Safeguards and Security Considerations

From a security perspective, all SMR-160+ safety systems are located within and protected by a robust and secure Containment Enclosure Structure. There are fewer vital areas and equipment necessary to maintain the plant in a safe shutdown condition, and the Containment is inaccessible and resistant to radiological sabotage. The Containment is sealed during operation and entry is not possible. This is an advantage over current operating plants as it significantly reduces the number of “target” for the plant and the required size of the security force. The site layout is amenable to use of drones, robots, and remote monitoring for security. 

Spent Fuel Management and Profile

SMR-160+ accommodates interim storage of spent fuel within an underground Independent Spent Fuel Storage Installation ISFSI within the plant’s Protected Area. For fuel to be placed into dry storage, requirements for decay heat, burnup, and cooling time of the spent fuel need to be met. These are contingent on the licensing requirements of the dry storage system. After the third SMR-160+ refueling outage, discharged spent fuel from the first operating cycle will be removed from the SFP Spent Fuel Pool and placed into underground dry storage in the HI-STORM UMAX Storage System.


  • The reactor core is located deep underground.
  • No reliance on on-site or off-site power to shut down the reactor and to reject the decay heat to the environment (hence, Inherently Safe).
  • Passively cooled for design basis shut down. The reactor coolant system continues to circulate by thermo-siphon action during accident scenarios
  • No active components (pumps) performing any safety function.
  • For maximum security, all vital equipment is located in protected and inaccessible areas. NSSS components are located underground.
  • The containment is a steel structure that will serve to dissipates heat to the environment using passive cooling for a design basis event.
  • All safety-related systems are inside containment.
  • Large pipe break loss of coolant accidents (LOCA) rendered are non-credible by design: no large piping in the Reactor Coolant System (RCS) loop.
  • Fuel is protected by an airplane crash resistant containment enclosure structure; 100% of the site source term is inside the containment – fuel in the reactor and the spent fuel pool.
  • The reactor system is designed to withstand extreme events postulated for US and International sites.
  • A tall column of water above the reactor core provides large coolant inventory, ensuring the core is never uncovered and ensuring the peak fuel and clad temperatures never exceed normal operating temperatures.
  • No penetrations in the reactor vessel below the safety injection nozzle, minimizing risk of core uncovering.