PENNSYLVANIA NUCLEAR ENGINEER EXAM
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2025|2026 Q&A |
INSTANT DOWNLOAD PDF
1. The neutron life cycle in a reactor includes all the following EXCEPT:
• a) Fission neutron production
• b) Fast neutron slowing down
• c) Thermal neutron absorption
• d) Moderation
Rationale: Fission neutron production is part of the cycle, not a separate life stage;
the life cycle refers to neutron behavior after production.
2. The effective multiplication factor keff=1keff=1 indicates:
• a) Subcritical reactor
• b) Critical reactor
• c) Supercritical reactor
• d) Reactor shutdown
Rationale: keff=1keff=1 means each fission leads to exactly one subsequent fission
on average.
3. Which material is commonly used as a moderator in light water reactors?
• a) Water
• b) Graphite
• c) Heavy water
• d) Boron carbide
,4. The delayed neutron fraction is important for:
• a) Fuel enrichment
• b) Reactor control and stability
• c) Waste disposal
• d) Heat transfer
5. The primary fissile isotope used in most commercial reactors is:
• a) U-235
• b) Pu-239
• c) Th-232
• d) U-238
6. Fast reactors primarily rely on:
• a) Moderation by light water
• b) Fast neutrons without moderation
• c) Graphite moderation
• d) Heavy water moderation
7. Neutron flux is defined as:
• a) Energy released per fission
• b) Rate of fission reactions
• c) Number of neutrons per unit area per unit time
• d) Total neutron population
8. Control rods in a nuclear reactor primarily:
• a) Increase thermal conductivity
• b) Increase fuel enrichment
• c) Absorb neutrons
, • d) Slow down neutrons
9. A reactor is considered supercritical if keffkeff is:
• a) <1
• b) >1
• c) =1
• d) ≤0
10. In a PWR, the primary coolant loop:
• a) Directly drives turbines
• b) Transfers heat to the secondary loop
• c) Is open to the atmosphere
• d) Contains boron only in trace amounts
11–20: Thermodynamics & Heat Transfer
11. The Rankine cycle is used in nuclear power plants for:
• a) Converting thermal energy to electrical energy
• b) Enriching fuel
• c) Reactor cooling
• d) Controlling neutron flux
12. The boiling point of water increases in a pressurized reactor due to:
• a) Neutron flux
• b) Elevated pressure
• c) Moderator presence
• d) Control rods
13. The heat transfer in a fuel rod is primarily by:
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2025|2026 Q&A |
INSTANT DOWNLOAD PDF
1. The neutron life cycle in a reactor includes all the following EXCEPT:
• a) Fission neutron production
• b) Fast neutron slowing down
• c) Thermal neutron absorption
• d) Moderation
Rationale: Fission neutron production is part of the cycle, not a separate life stage;
the life cycle refers to neutron behavior after production.
2. The effective multiplication factor keff=1keff=1 indicates:
• a) Subcritical reactor
• b) Critical reactor
• c) Supercritical reactor
• d) Reactor shutdown
Rationale: keff=1keff=1 means each fission leads to exactly one subsequent fission
on average.
3. Which material is commonly used as a moderator in light water reactors?
• a) Water
• b) Graphite
• c) Heavy water
• d) Boron carbide
,4. The delayed neutron fraction is important for:
• a) Fuel enrichment
• b) Reactor control and stability
• c) Waste disposal
• d) Heat transfer
5. The primary fissile isotope used in most commercial reactors is:
• a) U-235
• b) Pu-239
• c) Th-232
• d) U-238
6. Fast reactors primarily rely on:
• a) Moderation by light water
• b) Fast neutrons without moderation
• c) Graphite moderation
• d) Heavy water moderation
7. Neutron flux is defined as:
• a) Energy released per fission
• b) Rate of fission reactions
• c) Number of neutrons per unit area per unit time
• d) Total neutron population
8. Control rods in a nuclear reactor primarily:
• a) Increase thermal conductivity
• b) Increase fuel enrichment
• c) Absorb neutrons
, • d) Slow down neutrons
9. A reactor is considered supercritical if keffkeff is:
• a) <1
• b) >1
• c) =1
• d) ≤0
10. In a PWR, the primary coolant loop:
• a) Directly drives turbines
• b) Transfers heat to the secondary loop
• c) Is open to the atmosphere
• d) Contains boron only in trace amounts
11–20: Thermodynamics & Heat Transfer
11. The Rankine cycle is used in nuclear power plants for:
• a) Converting thermal energy to electrical energy
• b) Enriching fuel
• c) Reactor cooling
• d) Controlling neutron flux
12. The boiling point of water increases in a pressurized reactor due to:
• a) Neutron flux
• b) Elevated pressure
• c) Moderator presence
• d) Control rods
13. The heat transfer in a fuel rod is primarily by:
