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Advanced Nuclear Reactors

Turbulent Flow of Coolant in an Advanced Nuclear Reactor

Visualizing Coolant Flow in Sodium Reactor Subassemblies

Sodium-cooled Fast Reactor (SFR) Coolant Flow

At the heart of a nuclear power plant is the reactor. The fuel assembly is placed inside a reactor vessel where all the nuclear reactions occur to produce the heat and steam used for power generation. Nonetheless, an entire power plant consists of many other support components and key structures like coolant pipes; pumps and tanks including their surrounding steel framing; and concrete containment and support structures.

The Reactors Product Line within NEAMS is concerned with modeling the reactor vessel as well as those components of a complete power plant that are key to understanding and predicting its performance, safety and reliability. This includes simulating a plant’s response to catastrophic events such as earthquakes or loss of primary cooling systems. These tools will provide 3-D, high-fidelity simulations which will better inform scientists and engineers considering design and safety issues in all sectors of industry, academia and government.

Like all of the NEAMS toolkit, the Reactors Product Line is focused on addressing the needs of designers and analysts in studying advanced, non-water reactor systems.Building a capability to address such a broad class of potential designs is tractable because much of the phenomena that govern their behavior is shared.  For example, the behavior of thermal fluids needs to be considered for all reactor designs since they all contain coolants at various temperatures.

It’s important to note that experimental data acquired from testing real reactor system components is critical for comparing to simulation results. These comparisons help to improve confidence that modeling and simulation tools being developed match real-world experiments.


The RELAP-7 system analysis module, based on the code RELAP-7, provides one-dimensional lumped parameter system performance and safety analysis capability.  RELAP-7 will simulate behavior at the plant level, in other words address a broad range of phenomena at a level of detail that is feasible and appropriate for a plant scale of modeling as opposed to analyzing highly localized phenomena in great detail at every point in the plant. Early development will focus on the capabilities needed for Light Water Reactor (LWR) safety analyses although it will be extended to support advanced reactors as well. 


SHARP is the name given to the collective suite of high-fidelity reactor simulation tools comprised of thermal hydraulic, neutronics, and structural mechanics modules as well as various supporting elements tools that will collectively form the Reactors Product Line of the NEAMS ToolKit.  Each module can be utilized as a standalone code component or as part of an integrated analysis.  SHARP was developed with technology neutral simulation capabilities in mind so that it could extend to all types of advanced reactors.  Initial efforts focus on development of tools for analysis of performance and safety of Sodium-cooled Fast Reactors (SFR), and will demonstrate the passive safety characteristics of SFRs resulting from multi-physics thermal-structural-neutronics phenomena.