Difficulty: Easy
Correct Answer: constant
Explanation:
Introduction / Context:
Reactor criticality is a foundational concept in nuclear power. It describes the balance between neutron production (via fission) and losses (via absorption and leakage). Understanding the terms subcritical, critical, and supercritical is essential for safe operation and control.
Given Data / Assumptions:
Concept / Approach:
A reactor is critical when the effective multiplication factor keff = 1. At this condition, each generation of neutrons produces exactly one subsequent generation of the same size, so neutron population and hence reactor power remain constant over time.
Step-by-Step Solution:
Verification / Alternative check:
Examine reactor power trends: during long steady operation, heat removal (steam generation) balances fission heat production, indicating constant neutron flux and critical state.
Why Other Options Are Wrong:
Common Pitfalls:
Equating “critical” with “dangerous”. In nuclear engineering, “critical” simply means steady-state chain reaction, not instability.
Final Answer:
constant
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