NSUF 24-4819: Phase Characterization of Neutron Irradiated Surveillance Reactor Pressure Vessel Welds

A nuclear power plant's reactor pressure vessel (RPV) is an essential structural element. A catastrophic failure caused by a brittle fracture in the RPV, which acts as a pressure boundary component, might cause severe core damage and possibly result in the widespread release of radioactivity. In the 1960s, the Nuclear Regulatory Commission (NRC) mandated that RPVs be forged in one piece, without welds due to early RPV submerged-arc welds being prone to catastrophic cracking due to the radiation environment. Due to this regulation of welds in RPVs, the cost of creating and repairing RPVs has increased significantly, which hinders the ability to deploy new reactors and continue the operation of existing ones. Therefore, the aim of this research is to study the effects of irradiation damage on the phase distribution in surveillance RPV arc welds and compare them to electron beam (EB) welds. This study hypothesizes that due to the utilization of weld filler metal in arc-welded RPVs, they may exhibit a greater susceptibility to embrittlement when compared to autogenous EB welds. The increased susceptibility is often completely attributed to the higher content of Mn and Cu in the arc-weld material, as these elements are known to contribute to the precipitation of embrittlement-inducing precipitates. However, this susceptibility also may stem from the destabilization of certain phases caused by the radiation-induced segregation of alloying elements such as Mn, Cu, and P, and the resultant phases being more susceptible to irradiation embrittlement. This hypothesis will be tested by conducting phase characterization of surveillance RPV arc welds (from the NSUF Fuels and Materials Library) using advanced electron microscopy techniques such as scanning electron microscopy (SEM) in backscattered electron (BSE) mode, high-resolution energy dispersive spectroscopy (EDS) using transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Experimental data will be compared with irradiated EB-welded RPV steel microstructures that our team is currently analyzing. The outcomes of this work will include an understanding of how irradiation affects the phase distribution in RPV welds and how susceptible those phases are to embrittlement, providing insight into the ideal initial microstructure to mitigate irradiation effects.

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Поле	Стойност
Award Announced Date	2024-02-02T12:12:52.36
Awarded Institution	Purdue University
Facility Tech Lead	Kory Linton, Yaqiao Wu
Irradiation Facility
PI	Jasmyne Emerson
PI Email	[email protected]
Project Type	RTE
RTE Number	None