Chapter 3

Question 1

What is the equation for enthalpy?

Answer 1

H = U + PV

Question 2

What is the equation for the Gibb’s free energy at constant pressure?

Answer 2

G = H - TS

Question 3

What is the specific heat?

Answer 3

quantity of heat required to rais the temperature by one degree kelvin at constant pressure.

Question 4

What are intensive properties?

Answer 4

Independent of size (T and P)

Question 5

What are extensive properties?

Answer 5

Size/quantity dependent (V, U, H, S, and G)

Question 6

What is the Latent Heat?

Answer 6

heat released or absrobed by a chemical substance or a thermodynamic system during a process that occurs without a change in temperature

Question 7

What does “undercooling the melt” means?

Answer 7

It means cooling faster than the material is able to crystallize

Question 8

During crystallization is heat being released or absorbed

Answer 8

released

Question 9

What type of grains are created during slow cooing process?

Answer 9

round

Question 10

What type of grains are created during slow cooing process?

Answer 10

Dendritic grains

Question 11

What shape allows for the minimum surface energy?

Answer 11

Sphere

Question 12

What are wulff crystals?

Answer 12

Crystals that grow assymetrically due to areas with higher surface energy

Question 13

Which side grows faster in a crystal: ones with lower or higher surface energy? What shape?

Answer 13

Sides with higher surface energy like flat surfaces.

Question 14

What does the entropy of mixing consist of?

Answer 14

i) configurational and ii) vibrational or thermal entropy

Question 15

Entropy of mixing consists of configurational and vitrational (thermal) entropy? Which is larger?

Answer 15

Configurational. Vibrational or thermal are often negletegted to first order.

Question 16

How can activities be measured in the context of chemical potentials?

Answer 16

1) partial pressure of vapor in equilibrium with a solid, 2) electrolitic transfer in a galvanic cell (EMF), 3) Equilibrium with ideal solution (reference) and concentration measurment

Question 17

What is a phase?

Answer 17

uniform state of matter within a system that is physically distinguishable in terms of composition and structure from other states and theoretically separable

Question 18

What is the phase rule?

Answer 18

relates the physical state of a mixture to the # of constituents in the system and to its conditions.

Question 19

What are the three gamma stabilizers?

Answer 19

Ni, Co, Mn

Question 20

What are gamma stabilizers?

Answer 20

Components that enlarge the gamma phase therefore increasing solubility.

Question 21

What are alpha stabilizers?

Answer 21

gamma phase reduced and alpha enlarged

Question 22

Name all alpha stabilizers

Answer 22

Cr, Al, Ti, Si, Mo, W, V

Question 23

What is the dominant cause of RPV embrittlement?

Answer 23

Formation of high number density of nanometer copper rich precipitates

Question 24

How does copper end up in the RPV and what enhances its diffusion through it causing precipitates?

Answer 24

from scrap metal or during welding and although at 300 C the driving force is enough, it is slow. Radiation enhances diffusion rates due to excess vacancy populations

Question 25

Why does the zircaloy cladding goes brittle?

Answer 25

Because of Hydrogen absorption by cladding. Hydrogen precipitates into hybride phase (ZrHn) causing the material to go brittle

Question 26

What are some sources of hydrogen in a PWR that can lead to cladding embrittlement?

Answer 26

1. native hydrogen remaining in cladding after fabrication
2. waterside corrosion of cladding
   2.1 H produced by metal inside cladding by water entering fuel-cladding gap due to leaks
3. H added to water purposly to scavage oxygen
   etc.

Question 27

What happens to the solidus line when fast cooling?

Answer 27

It shifts and its larger the bigger the cooing rate.

Question 28

What is the crystal structure of martensite? and what changes from its normal arrangement?

Answer 28

BCT (tetragonal body centered) but carbon atoms sit in octahedron spaces.