NSUF 16-782: Micro-structural and -chemical Investigations of the Short-Term Annealing of Irradiation-Induced Late Blooming Phase Precipitates in a High-Ni Reactor Pressure Vessel Steel Weld

Embrittlement of reactor pressure vessel (RPV) steels by irradiation is a critical issue that is accepted to be the limiting factor for plant life of light-water reactors (LWRs). The primary objective of the DOE Light-Water Reactor Sustainability (LWRS) Program RPV task is the development of robust predictions of transition temperature shifts (TTS) at high neutron fluences (E > 1 MeV) pertinent to pressurized water reactor (PWR) plant operation up to 80 years. Surveillance specimens from the Ringhals nuclear power plant (Gothenburg, Sweden) that have been irradiated up to ~20 effective full power years (EFPY) are key unique specimens due to their very high TTS following irradiation. Embrittlement of RPV steels is known to occur due to microstructural evolution in the form of copper-enriched, or NiMnSi precipitates. In high-nickel materials, the so-called late blooming phases associated with the NiMnSi precipitates that form under irradiation are of particular interest. The work to be conducted under the proposed work will use state-of-the-art microscopy techniques to characterize NiMnSi precipitates at a near- atomic-scale following thermal annealing in 1 hour steps. The results to be obtained will further the knowledge of the formation and recovery mechanisms of these precipitates. The research is expected to be conducted within 6 months from the start of the project, including sample preparation, data acquisition, and analysis.

Additional Info

Field	Value
Abstract	Embrittlement of reactor pressure vessel (RPV) steels by irradiation is a critical issue that is accepted to be the limiting factor for plant life of light-water reactors (LWRs). The primary objective of the DOE Light-Water Reactor Sustainability (LWRS) Program RPV task is the development of robust predictions of transition temperature shifts (TTS) at high neutron fluences (E > 1 MeV) pertinent to pressurized water reactor (PWR) plant operation up to 80 years. Surveillance specimens from the Ringhals nuclear power plant (Gothenburg, Sweden) that have been irradiated up to ~20 effective full power years (EFPY) are key unique specimens due to their very high TTS following irradiation. Embrittlement of RPV steels is known to occur due to microstructural evolution in the form of copper-enriched, or NiMnSi precipitates. In high-nickel materials, the so-called late blooming phases associated with the NiMnSi precipitates that form under irradiation are of particular interest. The work to be conducted under the proposed work will use state-of-the-art microscopy techniques to characterize NiMnSi precipitates at a near- atomic-scale following thermal annealing in 1 hour steps. The results to be obtained will further the knowledge of the formation and recovery mechanisms of these precipitates. The research is expected to be conducted within 6 months from the start of the project, including sample preparation, data acquisition, and analysis.
Award Announced Date	2016-12-16T07:45:10.967
Awarded Institution	Center for Advanced Energy Studies
Facility	Microscopy and Characterization Suite
Facility Tech Lead	Kory Linton, Yaqiao Wu
Irradiation Facility	None
PI	Philip Edmondson
PI Email	[email protected]
Project Type	RTE
RTE Number	782