Fluids & Structural Mechanics > CM Projects > Nuclear Reactor Thermal-Hydraulics (NRTH)

Images | Animations (Below)

The Division's thermal-hydraulic research activities include the development of detailed two-fluid (gas and liquid) models for analyzing various nuclear reactor coolant loop accident scenarios. The models and software are used extensively by the Nuclear Regulatory Commission and others for design, licensing, and safe operation of nuclear power plants.

TRAC/RELAP Advanced Computational Engine (TRACE) is the latest best-estimate reactor analysis codes developed by the U.S. Nuclear Regulatory Commission. This code package is capable of modeling both steady-state and transient neutronic-thermal-hydraulic behavior of light water reactors (both Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs) as well as test facilities designed to simulate reactor accident scenarios. The models developed here at ARL are used directly in TRACE.

Another related CM Division is research and code development related to automated systems code accuracy assessment.

Images
image
View Image (145kb)

Figure 1:

This is a coarse but typical nodalization of the primary loop of a Pressurized Water Reactor (PWR). This model was developed to analyze a loss of coolant accident for the Zion 4-loop PWR . It is a Westinghouse 4 loop nuclear reactor. One of the main coolant loops has a broken pipe indicated by the label "Broken Loop" on the figure. The remaining three coolant loops are combined into one large loop labeled "Intact Loop" on the figure.
image
View Image (117kb)

Figure 2:

This figure shows a coarse nodalization of the Zion 4-loop pressurized water reactor steam generators. These are for the same model shown in Figure 1. One steam generator is for the broken loop the other represents the steam generators for the other three loops.

Animations
image
View Animation
(Flash Player 18.4mb)

Animation 1:

Boiling Water Reactors (BWR) are susceptible to periodic power and hydraulic oscillations. These instabilities can compromise the fuel safety limits set by the NRC. It is important to be able to accurately model this phenomena. This TRACE animation shows the power fluctuations during a boiling water reactor instability event. At 80 seconds you can see the instability start and power spikes to 8 times the rated power of the reactor. This animation also shows that the instability can also rotate around the core.