Nuclear Science Awareness and Industrial Safety
Nuclear Science Awareness covers fission, fusion, reactor components, the fuel cycle, criticality, and PHWR fundamentals. Industrial Safety covers permit-to-work, PPE, fire, electrical, confined-space, and lockout/tagout controls. The exam favours clear definitions and safe-sequence reasoning.
Core rules
- U-235 fission releases about 200 MeV per fission; a chain reaction depends on the neutron multiplication factor k.
- k < 1 is subcritical, k = 1 is critical and steady, k > 1 is supercritical.
- A moderator slows fast neutrons; heavy water (D₂O) is the moderator in Indian PHWRs; control rods absorb neutrons.
- The nuclear fuel cycle includes mining, conversion, enrichment or heavy-water use, fabrication, irradiation, reprocessing, and waste management.
- Permit-to-work authorises specific maintenance with hazards identified, isolation confirmed, and a responsible person signing off.
- Fire needs fuel, oxygen, and heat; remove one side of the fire triangle to extinguish.
Worked example. If a reactor has k = 1, each fission generation produces exactly one surviving neutron that causes another fission. Power remains steady at the existing level. If k = 1.001, the neutron population rises slowly; if k = 0.999, it falls. A reactor is not "critical" in the everyday sense of dangerous; it is critical in the physics sense of a self-sustaining chain reaction.
Traps. Do not confuse moderator with control rod; heavy water is not the same as light water; fusion powers the Sun but current power reactors use fission; criticality means steady state, not automatic runaway; lockout/tagout must be applied before maintenance on energised equipment.