Computer models are developed using the latest software from National Laboratories and Industry

MsNB’s design is simplified to utilize natural circulation instead of mechanical pumps to move the molten salt around the reactor.
Natural circulation relies on the same principle as in a hot air balloon. The neutron fission reaction generates heat which increases the molten salt temperature in the core. The molten salt is now buoyant and rises naturally. like a hot air balloon. At the top or the MsNB, heat is removed to generate electricity or hydrogen, cooling the molten salt. The reduction in molten salt temperature causes it to lose buoyancy and flow downward, just as a hot air balloon lands. Simultaneous core heating and heat removal generates the molten salt natural circulation flow.
The advanced computational models have the capability to simulate the neutronic fission heating and resulting fluid flow environments as well as the structural integrity of MsNB. The models provide tremendous insights into the design process.


Station Blackout Total Loss of Heat Sink Transient MsNB is Walkaway Safe

Model developed for MicroNuclear LLC at Argonne National Laboratory and support from NRIC
  • Fully coupled thermal hydraulics neutronics (includes delayed neutron groups) with temperature reactivity feedback
  • 100% Power to Total Loss of Heat Sink in 10 seconds
  • Structure temperatures within Safety Limits

Control Rod Angular Worth

Computer simulation demonstrating MsNB controllability with rotating control drum design.

Thermal Effects: Negative Temperature Coefficient

Estimates demonstrate MsNB passive safety, as core temperature increases, power decreases.
MsNB reactor power automatically shuts down if there is and unintended temperature increase

Burnup Simulation Results

Demonstrates the ability of MsNB is to operate for ten years.

Neutronics Modeling

Presents results of MsNB neutronic activity at different elevations in the reactor.


Simplified overview of MsNB design with natural circulation – Initial CFD Model