The power output of a U-235 fission reactor is 100 kW. What is the mass of U-235 consumed per hour (about 200 MeV released per fission)?
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Question

The power output of a U-235 fission reactor is 100 kW. What is the mass of U-235 consumed per hour (about 200 MeV released per fission)?

G1 Physics · Accepted Answer

Total energy per hour = (100 × 10³ W)(3600 s) = 3.6 × 10⁸ J. Energy/fission = 200 MeV = 200 × 1.602 × 10⁻¹³ = 3.204 × 10⁻¹¹ J. Fissions/hour = (3.6 × 10⁸)/(3.204 × 10⁻¹¹) ≈ 1.12 × 10¹⁹. Mass = (1.12 × 10¹⁹)(235 g/mol)/(6.022 × 10²³ mol⁻¹) ≈ 4.38 × 10⁻³ g = 43.8 μg. Nearest option: 40 μg (B). Final answer: Option B.