Locations in the reactor system, in addition to the reactor pressure vessel, that are primary concerns for thermal shock include the pressurizer spray line and the purification system.

Summary

The important information in this chapter is summarized below.

Pressurized Thermal Shock Summary

Definition of pressurized thermal shock (PTS)

Shock experienced by a thick-walled vessel due to the combined stresses from a rapid temperature and/or pressure change.

Pressure in closed system raises the severity of thermal shock due to the additive effect of thermal and pressure tensile stresses on the inside reactor vessel wall.

Plant transients with greatest potential to cause PTS include: Excessive heatup and cooldown

Plant scrams

Plant pressure excursions outside of normal pressure bands Loss of coolant accident

Locations of primary concern for thermal shock are: Reactor Vessel

Pressurizer spray line Purification system