HYDRIDE CRACKING IN ZIRCONIUM ALLOYS IS ONE OF THE MAJOR CAUSES OF FAILURE AND CONSIDERING THE IMPORTANCE OF THIS TYPE FAILURE WE HAVE REVIEWED THE SITUATION THAT MAKES ZIRCONIUM ALLOYS VULNERABLE TO CRACKING. THE RESULTS SHOW THAT MOST OF ATOMIC HYDROGEN IS PRODUCED IN NORMAL CORROSION PROCESS ALBEIT; ABSORPTION DEPENDS ON VARIOUS FACTORS. THE RECENT INVESTIGATIONS REVEALED THAT, RADIAL HYDRIDES ARE MORE DISASTROUS COMPARED TO CIRCUMFERENTIAL HYDRIDES.

THE ULTRASOUND PROCESS IS A NEW METHOD FOR CRACKING OF HEAVY PETROLEUM RESIDUE. ALL EXPERIMENTS WERE PERFORMED ON RESIDUAL FUEL OIL OF TABRIZ PETROCHEMICAL COMPANY. THREE SAMPLES WITH VARYING (0%, 20%, 50%) OF WATER THAT WERE SONICATED FOR 1 HOUR AND THE RESIDUAL FUEL OIL WITHOUT SONICATION FOR COMPARING WERE ANALYZED BY CENTRAL LABROTARY AT TABRIZ PETROCHEMICAL COMPANY USING A GAS CHROMATOGRAPH WITH FLAME IONIZATION DETECTOR (GC-FID). THE AMPLITUDE OF 100% (400 WATTS), 24 KHZ FREQUENCY AND AN ULTRASONIC PROBE WITH 3MM TIP DIAMETER WAS USED FOR ALL EXPERIMENTS. THE GC ANALYSIS RESULTS INDICATED THAT THE AMOUNTS OF HEAVY COMPONENTS LIKE INDANE+DCPD AND AR12 WERE REDUCED AFTER SONICATION. SOME LIGHT COMPONENTS LIKE BENZENE WERE INCREASED AFTER SONICATION. ALL THESE RESULTS SHOW THAT SONICATION PROCESS CAN HELP CRACKING OF HEAVY PETROLEUM FRACTIONS TO LIGHT AND USABLE COMPONENTS.