Rx kinetics

Question 1

Properties of a Prompt Neutron

Properties of a Delayed Neutron

Answer 1

Prompt

• born within 10-14 seconds after fission (i.e. 10-16 sec)
• average energy 2.0 Mev

Delayed

• born after 10-14 seconds after fission (avg. 12.5 sec)
• average energy 0.5 Mev

Question 2

What is the “effective delayed neutron fraction” (Beta bar eff)?

What is a “reactor Period”?

What is “prompt criticality?

Answer 2

Beff - fraction of all neutron induced fissions caused by delayed neutrons

Rx period - time in seconds for Rx power to change by a factor of “e”

Pmpt crtcl - condition where Rx is critical on prompt neutrons alone (reactivity =/> B bar eff)

Question 3

When can the SUR power equation be used? (P = P_o10^sur(t) )

Define SUR?

Answer 3

when you have a stable SUR (criticality to POAH, i.e. No feedbacks)

Number of times reactor power changes by a factor of 10 in one minute