High resolution electron microscopy study on the thin oxide films formed on type 316L stainless steel exposed under simulated BWR water chemistry conditions

• This paper describes the microstructures of the oxide films formed on a type 316L stainless steel material exposed under simulated BWR water chemistry conditions. High resolution electron microscopy (both FE-SEM and FE-TEM) was used. A TEM specimen was prepared by using focused ion beam technique. It is revealed that the inner thin oxide layer, unlike commonly believed, contains a large fraction of voids in some locations. There are concentration gradients of Fe, Ni and Cr elements in this layer. Furthermore, the TEM investigation revealed that the relatively large grains as commonly seen on the corroded surface sometimes consist of several small crystals of either different crystallographic orientations or different chemical compositions. The implication of the observed microstructures of the oxide films to the radioactivity build-up on BWR plant system piping surfaces is elaborated.

Ämnesord

NATURVETENSKAP  -- Fysik -- Annan fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Other Physics Topics (hsv//eng)

Nyckelord

Chemical compositions

Concentration gradients

Corroded surface

Crystallographic orientations

Focused ion beam technique

Large-grain

Plant systems

SEM

Small crystals

TEM

Thin oxide films

Thin oxide layers

Type 316L stainless steel

Water chemistry

Boiling water reactors

Chromium

Degradation

High resolution electron microscopy

Ion beams

Microstructure

Nuclear energy

Stainless steel

Oxide films

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