Question

Water is used as a coolant in a nuclear reactor because of its

• A. high thermal expansion coefficient
• B. high specific heat capacity
• C. low density
• D. low boiling point

Answer 1

The Correct Option is B

Water is an effective coolant in a nuclear reactor due to its high specific heat capacity. Let's explore what makes this property ideal for cooling purposes:

1. High Specific Heat Capacity:
   • Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius.
   • Water has a high specific heat capacity (approximately 4.186 joule/gram °C), which means it can absorb a significant amount of heat without experiencing a large increase in temperature.
   • This property is crucial in a nuclear reactor where substantial heat is generated. The ability of water to absorb and carry away this heat efficiently helps maintain the reactor’s temperature at safe levels.
2. Ineffectiveness of Other Options:
   • High thermal expansion coefficient: While important for some applications, this property does not directly aid in heat absorption or removal.
   • Low density: Lower density would not contribute to cooling ability; it might instead complicate circulation in the reactor.
   • Low boiling point: This would be unfavorable, as it would lead to boiling at lower temperatures, which could pose risks in a nuclear reactor environment.
3. Conclusion:
   • Therefore, the correct reason water is used as a coolant is its ability to absorb a lot of heat with a minimal change in temperature, which is attributed to its high specific heat capacity.