Nuclear Reaction & Mass Defect Calculator
Calculate nuclear binding energy, mass defect, and energy released in nuclear reactions using E=mc2.
Nuclear Energy Guide
Mass Defect and E=mc2
Nuclear mass is always less than the sum of its protons and neutrons. The mass deficit converts to binding energy: E = delta-m times c2. 1 atomic mass unit = 1.66054 x 10 to the -27 kg. 1u times c2 = 931.5 MeV. Mass defect of Fe-56: 26 protons + 30 neutrons - actual mass = 0.52847u. Binding energy = 0.52847 x 931.5 = 492.3 MeV = 8.79 MeV/nucleon. Iron has the highest binding energy per nucleon — neither fission nor fusion of iron releases energy.
Nuclear Fission
U-235 + n gives Ba-141 + Kr-92 + 3n + energy. Energy per fission approx 173 MeV. Energy per kg U-235 = approximately 71 TJ. Compare: 1kg coal releases 30 MJ. Nuclear fission is about 2 million times more energy dense than chemical fuel.
Nuclear Fusion
D-T fusion: deuterium + tritium gives helium-4 + neutron + 17.6 MeV. Energy per kg fuel approx 337 TJ. Requires 100 million degrees Celsius to overcome the Coulomb barrier. Stars achieve this through gravitational compression. ITER fusion reactor currently under construction in France.
Fission vs Fusion Waste
Fission waste: long-lived radioactive fission products (Cs-137 half-life 30 years, Sr-90 half-life 29 years) require secure storage for centuries. Fusion waste: primarily helium (inert) and neutron-activated reactor components (half-lives of decades, not centuries). This is one of the key advantages of fusion power over fission.
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