Chapter 8: RPV

Question 1

What happens when dislocations encounter precipitates and vacancy clusters? What effect does it have on mechanical properties?

Answer 1

Impede the motion of dislocations causing an elevation in yield strength.

Question 2

What does fracture toughness assess?

Answer 2

The resistance of a material to crack propagation.

Question 3

RPV suffers embrittlement due to…

Answer 3

fast neutron damage

Question 4

Fast neutron damage causes what change in the Kic value and in the DBTT?

Answer 4

reduction of Kic or an increase in the ductile-to-brittle transition temperature (Delta_T)

Question 5

How do you measure DBTT?

Answer 5

Charpy tests

Question 6

When could the DBTT increase cause a problem in a power plant?

Answer 6

When the ECCS cold water is injected into the system because of LOCA brittle failure is possible because of the rapid reduction in the inner wall temperature.

Question 7

What happens during a pressurized thermal shock?

Answer 7

ECCS cold water causes a rapid reduction in the inner wall temperature creating tensile thermal stresses which add to the existing stresses.