During the use of nuclear reactors the properties of the
structural materials change. Variations in the operation
environment, such as changes in water chemistry, may
enhance the development and growth of flaws. Neutron
radiation causes embrittlement for in-core vessel
materials. Radiation, together with water chemistry,
increases the possibility of stress corrosion cracking in
stainless steels and superalloys used in the reactor
internal parts. Research on structural materials
endeavours to study the ageing mechanisms of materials,
and the possibilities and methods of preventing or
forecasting the damage caused to structures by ageing.
The objective within the subproject "Material degradation
due to corrosive environment" of the RATU2 project was to
evaluate the factors affecting the changes in material
properties due to the environment and stresses, and to
assess their interrelationship. The subproject included
among others the following tasks:
· Development of routine EAC crack growth testing method
for small test specimens.
· Application of rising displacement testing to study
irradiation assisted stress corrosion cracking (IASCC).
New simplified techniques for determination of fracture
resistance curves in simulated reactor environments.
Multi-specimen bellows loading system to provide more
experimental EAC data than can be obtained with previous
servo hydraulic or mechanical loading systems.
|Conference||RATU2: The Finnish Research Programme on the Structural Integrity of Nuclear Power Plants|
|Period||7/12/98 → 7/12/98|