Reliability of reactor materials program: Semiannual progress report for period ending June 30, 1981

Kari Törrönen

Research output: Book/ReportReport


This is the first semiannual progress report for the Reliability of Reactor Materials Program, funded by the Ministry of Trade and Industry in Finland and the Technical Research Centre of Finland. In the area of quality technology the activity was started with a study of defects characterization by ultrasonic pulse-echo spectroscopy. Other techniques will be used in connection with the international PlSC-program. In the area of fracture mechanics work has been done to develop a modern computer interactive testing system for the fracture toughness evaluation of metallic materials. Also, a program for comparing computational and experimental elastic-plastic results was started. The testing system utilizes the unloading compliance single specimen method to develop crack growth resistance curves based on the J-integral concept and determines the relevant material parameters. By the end of the reporting period the testing of CT-type specimens became possible. Comparisons between computational and experimental elastic-plastic results are made using four different materials and four specimen geometries. A two-dimensional elastic-plastic code is used for the computational analysis. Preliminary irradiations for mechanisms and annealing studies have been conducted and nondestructive evaluations using the Barkhausen noise analysis and hardness tests have been initiated. Further irradiation for the evaluation of J-R curve characteristics of a weld material will be started in the near future. Long term thermal ageing studies have been continued. Accelerated annealings at 450°C for one year do not introduce any shift in the Charpy V transition temperature of SA 533B base material and only a slight increase was evident in the case of the corresponding weld material. In the area of environment sensitive cracking long term stress corrosion cracking studies of different austenitic stainless steels have been concluded and reported. Comparable studies concerning the ferritic pressure vessel and piping materials have been initiated. The first corrosion fatigue tests in the recently commissioned autoclave system have been completed successfully. Mechanistic studies of environment sensitive cracking in pressure vessel steels have been continued and a hydrogen-induced cracking model based on extensive fractography has been outlined. Corrosion studies have been concentrated on oxidation and decontamination of austeniti; stainless steels in both PWR and BWR conditions. In the area of low temperature sensitisation studies long term annealings of different stainless steel weld materials have been continued. A sub-project has been initiated to generate basic knowledge of the thermal fatigue behaviour of the materials used in nuclear power planes. During this reporting period a brief review of the problem areas has been compiled. In the area of repair welding the microstructural and hardness studies revelled that the half bead repair welding method man have some advantages compared try normal manual arc welding. The differences are, however, rather small and there exists a large scatter. The microstructural studies of the HAZ reveal that a perfect tempering effect is very difficult to obtain in halt bead repair welding due to the wavelike shape of the fusion line.
Original languageEnglish
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Number of pages110
ISBN (Print)951-38-1503-X
Publication statusPublished - 1982
MoE publication typeD4 Published development or research report or study

Publication series

SeriesValtion teknillinen tutkimuskeskus. Tutkimuksia - Research Reports


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