Which equation describes the behavior of fission product X over time after a reactor restart?

The chosen equation accurately reflects the factors influencing the behavior of fission product X over time after a reactor restart.

This equation encompasses several key components:

1. The term (γ_x Σ_f φ) accounts for the production of the fission product due to fission events, where (γ_x) is the yield of product X per fission, (Σ_f) is the fission cross-section, and (φ) is the neutron flux. This term illustrates how the rate of fission reactions contributes to the generation of fission products in the reactor environment.

2. The term (λ_i I) represents the contribution to the fission product inventory from an initial isotope concentration I, indicating that there may be a precursor or an external source contributing to the buildup of fission product X.

3. The term (-λ_x X) signifies the decay of fission product X over time, where (λ_x) is the decay constant of the product. This term demonstrates the natural decrease in quantity as the product undergoes radioactive decay.

4. Finally, the term (-σX φ) includes the loss of the fission product due to capture by other neutrons in the reactor,