NSUF 16-838: TEM Investigation of Irradiated Austenitic Stainless Steel Alloys
The proposed post-irradiation examination (PIE) activity will examine the helium bubble/cluster distribution of B-doped type 304L and 316 stainless steels to advance knowledge in the area of austenitic steel helium accumulation and segregation as a function of pre-irradiation boron content. Specifically, four conditions will be considered: 304L with 10wppm boron, 304L with 30wppm boron, 316L with 10wppm boron, and 316L with 30wppm boron. These materials have been fabricated with high purity, low-Co feedstock and precise chemistry controls to produce model alloys meeting the specified nominal boron concentrations. Special care was taken to observe fine grain practices and limit the formation of d-ferrite and metal carbides. Target chemical compositions were verified via optical emission spectroscopy (OES) and glow discharge mass spectrometry (GDMS) prior to irradiation. Pre-irradiated boron distribution analysis was performed via atom probe tomography (APT) for the alloys containing 30wppm boron. These results demonstrated differences in boron segregation behavior between 304L and 316L along high angle grain boundaries, suggesting that the post-irradiation helium distribution within the materials will differ. The mixed-spectrum high flux isotope reactor (HFIR) was utilized to irradiate the coupons with the goal of achieving complete burnup of B10 via the B10(n,a)Li7 transmutation reaction to control helium generation. Characterization of the materials will be carried out through a transmission electron microscopy (TEM) approach. Focused ion beam – scanning electron microscopy (FIB-SEM) will be utilized to selectively prepare foils for TEM that contain random high angle grain boundaries. Quantification of the helium bubble/cluster size and distribution will be carried out by capturing high resolution TEM micrographs. The resulting microstructure analysis and helium distribution will be correlated based on pre-irradiation boron content (10 and 30wppm) and stainless steel type (304L and 316L). The expected period of performance for this investigation is four to six months.
Additional Info
Field | Value |
---|---|
Abstract | The proposed post-irradiation examination (PIE) activity will examine the helium bubble/cluster distribution of B-doped type 304L and 316 stainless steels to advance knowledge in the area of austenitic steel helium accumulation and segregation as a function of pre-irradiation boron content. Specifically, four conditions will be considered: 304L with 10wppm boron, 304L with 30wppm boron, 316L with 10wppm boron, and 316L with 30wppm boron. These materials have been fabricated with high purity, low-Co feedstock and precise chemistry controls to produce model alloys meeting the specified nominal boron concentrations. Special care was taken to observe fine grain practices and limit the formation of d-ferrite and metal carbides. Target chemical compositions were verified via optical emission spectroscopy (OES) and glow discharge mass spectrometry (GDMS) prior to irradiation. Pre-irradiated boron distribution analysis was performed via atom probe tomography (APT) for the alloys containing 30wppm boron. These results demonstrated differences in boron segregation behavior between 304L and 316L along high angle grain boundaries, suggesting that the post-irradiation helium distribution within the materials will differ. The mixed-spectrum high flux isotope reactor (HFIR) was utilized to irradiate the coupons with the goal of achieving complete burnup of B10 via the B10(n,a)Li7 transmutation reaction to control helium generation. Characterization of the materials will be carried out through a transmission electron microscopy (TEM) approach. Focused ion beam – scanning electron microscopy (FIB-SEM) will be utilized to selectively prepare foils for TEM that contain random high angle grain boundaries. Quantification of the helium bubble/cluster size and distribution will be carried out by capturing high resolution TEM micrographs. The resulting microstructure analysis and helium distribution will be correlated based on pre-irradiation boron content (10 and 30wppm) and stainless steel type (304L and 316L). The expected period of performance for this investigation is four to six months. |
Award Announced Date | 2016-12-16T07:47:47.37 |
Awarded Institution | University of Michigan |
Facility | Michigan Ion Beam Laboratory |
Facility Tech Lead | Kevin Field, Kory Linton |
Irradiation Facility | None |
PI | Benjamin Sutton |
PI Email | [email protected] |
Project Type | RTE |
RTE Number | 838 |