EELS and electron diffraction studies on possible bonaccordite crystals in pressurized water reactor fuel CRUD and in oxide films of alloy 600 material

Nuclear Engineering and Technology

卷:49

Daniel Wells¹  Bernt Bengtsson²  Jiaxin Chen³  Fredrik Lindberg⁴ 

[1] Electric Power Research Institute, 1300 W WT Harris Blvd, Charlotte, NC 28262, USA;

[2] Ringhals AB, Ringhalsverket, SE-432 85 Väröbacka, Sweden;

[3] Studsvik Nuclear AB, SE-611 82, Nyköping, Sweden;

[4] Swerea KIMAB AB, Box 7047, SE-164 07 Kista, Sweden;

关键词: Alloy 600;    AOA;    Bonaccordite;    CIPS;    EDS;    EELS;    Electron Diffraction;    FIB;    Fuel CRUD;    Oxide Film;    PWR;    TEM;   

DOI  :  10.1016/j.net.2017.04.001

来源: DOAJ

【 摘 要 】

Experimental verification of boron species in fuel CRUD (Chalk River Unidentified Deposit) would provide essential and important information about the root cause of CRUD-induced power shifts (CIPS). To date, only bonaccordite and elemental boron were reported to exist in fuel CRUD in CIPS-troubled pressurized water reactor (PWR) cores and lithium tetraborate to exist in simulated PWR fuel CRUD from some autoclave tests. We have reevaluated previous analysis of similar threadlike crystals along with examining some similar threadlike crystals from CRUD samples collected from a PWR cycle that had no indications of CIPS. These threadlike crystals have a typical [Ni]/[Fe] atomic ratio of ∼2 and similar crystal morphology as the one (bonaccordite) reported previously. In addition to electron diffraction study, we have applied electron energy loss spectroscopy to determine boron content in such a crystal and found a good agreement with that of bonaccordite. Surprisingly, such crystals seem to appear also on corroded surfaces of Alloy 600 that was exposed to simulated PWR primary water with a dissolved hydrogen level of 5 mL H2/kg H2O, but absent when exposed under 75 mL H2/kg H2O condition. It remains to be verified as to what extent and in which chemical environment this phase would be formed in PWR primary systems.

【 授权许可】

Unknown