Reactor Theory (I)

Question 1

Radioactivity equation

Answer 1

Activity (after) = Activity(before) * e^[(-landa = LN(2)/ half-life)*time]

Question 2

Elements

Answer 2

defined by the number of protons in nucleus

Question 3

Isotopes

Answer 3

defined by the number of neutrons in nucleus

Question 4

Mass defect

Answer 4

difference between mass of atom and sum of individual necleons

Question 5

Binding energy

Answer 5

energy equivalent of mass defect; converts mass defect to MeV using 931.5 as conversion factors

Question 6

Microscopic Cross section

Answer 6

probability of neutron reactions to occur; measured in barns (1 barn = 10^-24 cm2)

Question 7

Mean free path

Answer 7

average distance neutron travels in material before interactions; landa = inverse cross section

Question 8

Macroscopic Cross section

Answer 8

atom density * micro cross section

Question 9

Reaction Rate

Answer 9

flux * macro cross section

Question 10

Fissile material

Answer 10

undergoes fission by neutron of any energy, usually odd numbered

Question 11

Fertile material

Answer 11

absorbs a neutron to become a fissile isotope

Question 12

Fissionable material

Answer 12

fissions by neutrons of some energy, usually even numbered

Question 13

Neutron generation time

Answer 13

prompt neutrons born 10^-4 seconds; delayed neutrons born 12.5 seconds after