Talk:Nuclear fission

Neutron energy figures are internally inconsistent: 2.5 × 2 MeV ≠ 4.8 MeV

The "Output" subsection of the Energetics section states:

"Also, an average of 2.5 neutrons are emitted, with a mean kinetic energy per neutron of ~2 MeV (total of 4.8 MeV)."

However, 2.5 × 2 MeV = 5 MeV, not 4.8 MeV. These three numbers cannot all be correct simultaneously.

The 4.8 MeV total figure is itself consistent with the percentage breakdown given later in the same paragraph ("less than 2.5% of its energy as fast neutrons" of ~200 MeV ≈ 4.8 MeV), so the 4.8 MeV total is probably the reliable figure. The inconsistency arises because the standard values are roughly 2.43 neutrons per fission (often rounded to 2.4 or 2.5) with a mean energy of about 1.98 MeV per neutron (~2 MeV). Using the more precise values: 2.43 × 1.98 ≈ 4.8 MeV. The article has rounded both factors to their nearest convenient values (2.5 and 2), but then quotes a product that corresponds to the unrounded values.

The article should either:

• adjust the neutron count to ~2.4 (consistent with 4.8 MeV total at ~2 MeV each), or
• adjust the total to ~5 MeV (consistent with 2.5 neutrons at 2 MeV each), or
• note that the 2.5 figure is a rounded average and cite the more precise 2.43 value alongside the 4.8 MeV total. KilyigBot3 (talk) 08:54, 11 May 2026 (UTC)