Experimental Set Up For Studying Temperature Gradient Driven Cracking


Reference #: 01509

The University of South Carolina is offering licensing opportunities for Experimental Set up for Studying Temperature Gradient driven cracking


The behavior of light water reactor (LWR) fuel is significantly affected by fracture, which is driven by multiple phenomena. Early in the life of fresh fuel, fracture is primarily caused by thermal stresses. The fission process in the cylindrical fuel pellets causes volumetric heating that in conjunction with the forced convective cooling on the exterior of the fuel rod results in a temperature profile with significantly higher values at the fuel centerline than at the fuel exterior, and which has a roughly parabolic shape. This leads to significant tensile stresses in the pellet exterior that result in crack initiation in fresh fuel, even during the initial ramp to power.

Invention Description:

This innovation along with LabView not only enables studying mechanical deformation and temperatures of materials but also records flow of gases and monitors oxygen partial pressure of reactive and inert gases.

Developing an experiment that permits quantification of the process of fracture initiation and growth in LWR fuel is challenging because it is difficult to both replicate the thermal conditions experienced by the fuel in the reactor and instrument the experiment in a way that permits observing crack growth.

The current work allows for imaging of the top surface of a fuel pellet to observe the formation of radial cracks. These experiments are being performed using a state-of-the-art experimental setup developed at the Nuclear Materials Laboratory at the University of South Carolina (USC). This system employs a unique dual imaging technique where the infrared camera captures the full field temperature gradient in the pellet and the optical camera system captures the physical images of cracks simultaneously in real time.

Potential Applications: 

For fuel performance codes to be predictive under a wide range of operating conditions, it is important for them to faithfully represent all aspects of behavior of the fuel system using physics-based models. Because of its important role on fuel behavior, improving the models for representing fracture has been a high priority in development of the BISON fuel performance code in recent years. Although significant advances have been made in modeling fracture, there is limited data available on the processes of fracture initiation and growth for direct validation of these models. A US Department of Energy (DOE) Nuclear Energy University Program (NEUP) project is supporting multiple experimental efforts, including the one described here, to provide improved data for validation of these models. These include out-of-reactor experiments, as well as a series of planned experiments in Idaho National Laboratory’s Transient Test Reactor (TREAT).

Advantages and Benefits:

The increased visibility and ability to view radial cracks allows for a better analysis of data and provides great benefit. Fuel fracture has important implications for fuel performance in normal operating conditions because it affects heat transfer through the fuel and the size of the fuel/cladding gap and can cause increased stresses in the cladding in the vicinity of fuel cracks. It is also of interest for understanding fuel behavior during accident conditions, because in the event of cladding rupture, dispersal of fuel fragments in the coolant is affected by their size.

Patent Information:
Title App Type Country Serial No. Patent No. File Date Issued Date Expire Date Patent Status
Experimental Set Up For Studying Temperature Gradient Driven Cracking Utility United States 17/506,928   10/21/2021     Filed
For Information, Contact:
Technology Commercialization
University of South Carolina
Travis Knight
Sobhan Patnaik
Theodore Besmann
Elwyn Roberts
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