Nuclear fission and chain reaction
Nuclear energy · Physics
Bohr atom
Interactive 3DElectrons orbit the nucleus in shells — switch element to see H, He and Li fill their shells.
Controls
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Study notes
(a) In a fission, ²³⁵U + n → ¹⁴¹Ba + ⁹²Kr + 3n. Verify nucleon and charge conservation. (b) If each fission releases 200 MeV, how many fissions per second produce 1 GW of thermal power? Solution: (a) Nucleons: 235 + 1 = 236; 141 + 92 + 3 = 236 ✓. Charge: 92 = 56 + 36 ✓. (b) 200 MeV = 200 × 1.602×10⁻¹³ = 3.2×10⁻¹¹ J. Fissions/s = 10⁹ / 3.2×10⁻¹¹ ≈ 3.1 × 10¹⁹ per second — yet this consumes only ~1.2 g of ²³⁵U per day per GW... actually ~1 g/day per MW thermal ≈ 1.2 kg/day for 1 GW.