In the four-factor formula kinf, what does the factor e represent?

In the four-factor formula kinf, what does the factor e represent?

• A. Production factor
• B. Thermal utilization factor
• C. Fast fission factor
• D. The ratio of fission cross section to absorption cross section

Answer: (C)

The e in kinf is the fast fission factor. It represents the extra neutrons produced by fission when some neutrons remain fast enough to cause fission before they slow to thermal energies. In many reactors, fast fission of fertile isotopes (like U-238) adds to the neutron population, so this factor is typically greater than one. This additional neutron production multiplies with the other factors to determine the overall infinite multiplication factor.

The e in kinf is the fast fission factor. It represents the extra neutrons produced by fission when some neutrons remain fast enough to cause fission before they slow to thermal energies. In many reactors, fast fission of fertile isotopes (like U-238) adds to the neutron population, so this factor is typically greater than one. This additional neutron production multiplies with the other factors to determine the overall infinite multiplication factor.