Calcolatore Energia Fissione Nucleare — Formula

Neutron Flux and Reaction Rate

Neutron flux is a fundamental quantity in nuclear reactor physics. It determines the rate of nuclear reactions.

Formulas

phi = n × v (neutron flux)

R = phi × Sigma = n × v × Sigma (volumetric reaction rate)

where n is neutron density, v is neutron speed, and Sigma is the macroscopic cross section. Thermal neutron velocity at room temperature is about 2200 m/s.

Esempio Risolto

A thermal reactor with n = 10⁸ n/cm³, v = 2.2 × 10⁵ cm/s, Sigma = 0.1 cm⁻¹.

  1. phi = 10⁸ × 2.2 × 10⁵ = 2.2 × 10¹³ n/(cm²·s)
  2. R = 2.2 × 10¹³ × 0.1 = 2.2 × 10¹² reactions/(cm³·s)