PSI - Issue 37

M. Annor-Nyarko et al. / Procedia Structural Integrity 37 (2022) 225–232 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Method 3.1. Reference transient event and the multi-step simulation implementation

The inadvertent SIS actuation PTS scenario selected for this study was investigated by Wang et al. (Wang et al., 2017). The unexpected action of the SIS caused the injection of colder water into the reactor coolant system leading to a rise in the loop pressure. The maximum injection flow rate was approximately 13 kg/s. The cooling water temperature and internal pressure distributions obtained from the AOO PTS event are shown in Fig. 3. The initial temperatures of the inner and outer surface of the RPV model are conservatively set to 289 o C and 20 o C respectively. In addition, the heat transfer coefficient between the air and the outer surface vessel is assumed to be 20 W/m 2 o C. The thermo-mechanical and fracture mechanics analyses were performed following the multi-step simulation procedure shown in Fig. 4.

Fig. 2. PTS transient reference data for temperature and pressure histories

Fig.3. Flow chart of the integrity assessment of RPV subjected to the AOO PTS loading