NSUF 17-1076: Characterization of Grain Boundary Damage in Highly Irradiated Specimens Exposed to Irradiation Assisted Stress Corrosion Cracking.

The objective of this work is to quantify, at the microscopic scale, the parameters that led to crack advance in two highly irradiated specimens that were tested in PWR environment. The specimens came from a same material and were irradiated to 33 dpa together. However, due to gamma heating, different swelling amounts were obtained. Well-controlled IASCC experiments have been conducted to measure, at the engineering scale, the difference of crack propagation rates between those specimens, i.e. the role of swelling in crack growth rates. It has been hypothesized that IASCC crack propagation in PWR environment is due to a combination of grain boundary embrittlement due to the environment and stress applied to this grain boundary. To support this hypothesis and develop predictive models, it is necessary to quantify these phenomena. The objective of the proposed work is to characterize the strain profile around the crack tips and the mechanical properties of the grain boundary ahead of the crack tips at the microscale and determine a correlation between engineering scale data and microscale data. The characterization of the strain field around and ahead of the crack will be done by EBSD, a map of hardness will be generated form the same area by nanoindentation and the cohesion of the grain boundary just ahead of the crack tip will be compared to the one of the same grain further away from the crack tip by micromechanical testing. The specimen will be available late August 2017 and the proposed work will take about 4 months to complete.

Additional Info

Field	Value
Abstract	The objective of this work is to quantify, at the microscopic scale, the parameters that led to crack advance in two highly irradiated specimens that were tested in PWR environment. The specimens came from a same material and were irradiated to 33 dpa together. However, due to gamma heating, different swelling amounts were obtained. Well-controlled IASCC experiments have been conducted to measure, at the engineering scale, the difference of crack propagation rates between those specimens, i.e. the role of swelling in crack growth rates. It has been hypothesized that IASCC crack propagation in PWR environment is due to a combination of grain boundary embrittlement due to the environment and stress applied to this grain boundary. To support this hypothesis and develop predictive models, it is necessary to quantify these phenomena. The objective of the proposed work is to characterize the strain profile around the crack tips and the mechanical properties of the grain boundary ahead of the crack tips at the microscale and determine a correlation between engineering scale data and microscale data. The characterization of the strain field around and ahead of the crack will be done by EBSD, a map of hardness will be generated form the same area by nanoindentation and the cohesion of the grain boundary just ahead of the crack tip will be compared to the one of the same grain further away from the crack tip by micromechanical testing. The specimen will be available late August 2017 and the proposed work will take about 4 months to complete.
Award Announced Date	2017-09-20T12:36:00.773
Awarded Institution	None
Facility	None
Facility Tech Lead	Peter Hosemann
Irradiation Facility	None
PI	Sebastien Teysseyre
PI Email	[email protected]
Project Type	RTE
RTE Number	1076