PSI - Issue 60

Rishi K Sharma et al. / Procedia Structural Integrity 60 (2024) 264–276 Rishi K. Sharma/ Structural Integrity Procedia 00 (2019) 000 – 000

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4. Results and Discussion A1. Burst test of as received pressure tube

Four numbers of part through wall (2.5 mm deep and 100 mm length) OD cracks were machined on as received pressure tube test spool of 1000 mm long. The pressure and temperature in the test spool were increased following a procedure until the pressure tube got burst at 171 bar pressure having a mean temperature of 210 °C. It was observed that one of the 4 part through OD axial cracks opened during the test. Visual examination of the pressure tube did not reveal any gross deformation. However, local plastic deformation at the opened crack location was observed. The outer Calandria Tube (CT) spool was examined visually after the experiment and no damage/ deformation of the CT was observed. A2. Burst test of pressure tube spool with 60-80 wppm circumferential hydrides A pressure tube spool of 475 mm long was charged with about 60-80 wppm of hydrogen. Four nos. of part through wall (2.5 mm deep and 100 mm length) OD cracks were machined on the test spool. The cracks were axially located at the center of the pressure tube and 90° apart in circumferential orientation. CT spool concentric to the pressure tube specimen was also employed maintaining the annulus space similar to reactor. The pressure and temperature of the test spool were increased following a procedure until the pressure tube got burst. The pressure and mean temperature at bursting were 142 bar & 210 °C respectively. It was observed that one of the 4 part through OD axial cracks opened during the test. A pressure tube spool of 475 mm long was charged with about 60-80 ppm of hydrogen. Stress reorientation treatment of the hydrogen charged pressure tube spools was carried out to form radial hydrides. As done for the previous experiment, four nos. of part through wall (2.5 mm deep and 100 mm length) OD cracks were machined on the test spool. The cracks were axially located at the center of the pressure tube and 90° apart in circumferential orientation. CT spool concentric to the pressure tube specimen was also employed maintaining the annulus space similar to reactor. The pressure and temperature of the test spool were increased following a procedure until the pressure tube got burst. The pressure and mean temperature at bursting were 92 bar & 210 °C respectively. It was observed that one of the 4 part through OD axial cracks opened during the test. A pressure tube spool of 475 mm long was charged with about 200 wppm of hydrogen. Stress reorientation treatment of the hydrogen charged pressure tube spools was carried out to form radial hydrides. Owing to limitation in temperature, only partial conversion to radial hydrides could be carried out. Four nos. of part through wall (2.5 mm deep and 100 mm length) OD cracks were machined on the test spool. The cracks were axially located at the center of the pressure tube and 90° apart in circumferential orientation. CT spool concentric to the pressure tube specimen was also employed maintaining the annulus space similar to reactor. The pressure and temperature of the test spool were increased following a procedure until the pressure tube got burst. The pressure and mean temperature at bursting were 98 bar & 210 °C respectively. It was observed that one of the 4 part through OD axial cracks opened during the test. Hence, the pressure tube got opened at comparatively lower pressure in presence of radial hydrides compared to as received material and with circumferential hydrides as shown in Figure 5 and Figure 6. A3. Burst test of pressure tube spool with 60-80 wppm radial hydrides A4. Burst test of pressure tube spool with 200 wppm mixed hydrides