Some number of the fast neutrons produced by fission in one generation will eventually cause fission in the next generation. The series of steps that fission neutrons go through as they slow to thermal energies and are absorbed in the reactor is referred to as the neutron life cycle. The neutron life cycle is markedly different between fast reactors and thermal reactors.This chapter presents the neutron life cycle for thermal reactors.

EO 1.1 DEFINE the following terms:

a. Infinite multiplication factor, k d. Critical

b. Effective multiplication factor, k_eff e. Supercritical

c. Subcritical

EO 1.2 DEFINE each term in the six factor formula using the ratio of the number of neutrons present at different points in the neutron life cycle.

EO 1.3 Given the macroscopic cross sections for various materials, CALCULATE the thermal utilization factor.

EO 1.4 Given microscopic cross sections for absorption and fission, atom density, and V, CALCULATE the reproduction factor.

EO 1.5 Given the numbers of neutrons present at the start of a generation and values for each factor in the six factor formula, CALCULATE the number of neutrons that will be present at any point in the life cycle.

EO 1.6 LIST physical changes in the reactor core that will have an effect on the thermal utilization factor, reproduction factor, or resonance escape probability.

EO 1.7 EXPLAIN the effect that temperature changes will have on the following factors:

a. Thermal utilization factor

b. Resonance escape probability

c. Fast non-leakage probability

d. Thermal non-leakage probability