Which risk increases when a reactor uses unenriched uranium fuel?

💡 Explanation

Neutron moderation becomes less efficient because unenriched uranium contains a higher proportion of uranium-238, which absorbs neutrons without fission. Therefore chain reactions are harder to sustain because neutron flux decreases, rather than thermal runaway that occurs with insufficient cooling.

• Which outcome occurs when a water-gas shift reactor experiences catalyst poisoning?
• Which limitation arises when designing Carnot cycle engines using materials near superconducting transition temperatures?
• Which risk increases in portable alpha spectrometers when radioisotope shielding degrades?
• Which consequence occurs during uncontrolled nuclear reactor fission?
• Which outcome occurs when excess product accumulates in reversible reaction?
• Which process limits the hydrogenation rate using transition metal catalysts?