Distribution of Tritium in the Near Surface of Type 316 Stainless Steel

Journal Article · 05 September 2019 · Fusion Science and Technology

DOI: https://doi.org/10.1080/15361055.2019.1644136 · OSTI ID:1574235

Sharpe, M. ^[1]; Fagan, C. ^[2]; Shmayda, W. T. ^[1]

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1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
2. Univ. of Rochester, NY (United States). Lab. for Laser Energetics, and Dept. of Chemistry

The distribution of tritium in the near surface of stainless steel, type 316, has been measured using a combination of a ZnCl₂ wash and acid etching with diluted aqua regia. This method improves upon etching measurements reported in the literature: results show depth resolutions of ~10 nm using the diluted aqua regia. The ZnCl₂ wash results show very high surface concentrations (~1.5 x10¹³ Bq/cm³), which decreases by a factor of 10⁶ after etching to a depth of ~10 um. Further, the tritium concentrations in the near surface (<10 um) of unmodified stainless-steel samples do not change significantly over the course of 233 days, which indicates a quasi-equilibrium state has been reached. Tritium migration to the surface from the subsurface region was measured by etching a sample, then storing it in air for 2 to 4 days. After storing in air, the surface concentrations increased a thousandfold and rapidly decreased to base levels after etching an additional ~2 um. Finally, these measurements indicate that perturbing the quasi-equilibrium concentration profile results in tritium migration to the surface in order to reestablish the prior equilibrium state.

• Research Organization: Univ. of Rochester, NY (United States). Lab. for Laser Energetics
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: NA0003856
• OSTI ID: 1574235
• Journal Information: Fusion Science and Technology, Vol. 75, Issue 8; ISSN 1536-1055
• Publisher: American Nuclear SocietyCopyright Statement
• Country of Publication: United States
• Language: English