Expert-level nuclear energy covering fission reactor physics, reactor types, safety systems, nuclear fuel cycle, waste management, and advanced reactor concepts.
Fission: heavy nucleus splits releasing energy and neutrons. Chain reaction: fission neutrons cause further fissions, sustained in reactor. Criticality: keff = 1 for sustained reaction, less than 1 subcritical, greater than 1 supercritical. Neutron moderation: slow neutrons more likely to cause fission in U-235. Moderators: light water, heavy water, graphite, beryllium.
PWR: pressurized water reactor, most common, primary and secondary loops. BWR: boiling water reactor, steam generated in core, simpler but radioactive turbine. CANDU: heavy water moderated, natural uranium fuel, online refueling. Fast reactors: no moderator, breed plutonium, burn actinides. SMR: small modular reactors, factory built, passive safety, flexible deployment.
Defense in depth: multiple independent safety barriers. Passive safety: natural circulation and gravity, no active components needed. Negative temperature coefficient: reactivity decreases as temperature rises, self-limiting. ECCS: emergency core cooling system, prevents fuel damage after loss of coolant. Containment: reinforced structure preventing radioactive release.
Front end: mining, conversion, enrichment, fuel fabrication. In-reactor: burnup measured in MWd per tonne, fission products accumulate. Back end: spent fuel storage, reprocessing, final disposal. Proliferation: enrichment and reprocessing dual-use concerns, safeguards.
| Pitfall | Fix |
|---|---|
| Confusing activity and dose | Dose depends on radiation type, energy, and shielding |
| Ignoring delayed neutrons | Critical for reactor control dynamics |
| Overlooking xenon poisoning | Xe-135 buildup after shutdown can prevent restart |
| Underestimating waste volume | All stages of fuel cycle generate waste |