Engineering requirements for a reactor moderator Beyond high slowing-down (moderating) power and low neutron absorption, a good moderator in nuclear reactors should also be…

Introduction / Context:
Moderators reduce neutron energy to the thermal range where fission cross-sections are high for many fuels. While neutronics drives the primary choice, engineering requirements determine whether a material can survive and perform inside a real reactor environment.

Given Data / Assumptions:

• Moderator must slow down neutrons effectively (high moderating ratio).
• Moderator should absorb as few neutrons as possible.
• It must survive thermal and radiation environments while transferring heat safely.

Concept / Approach:

Practical moderators (e.g., light water, heavy water, graphite) must be radiation-stable to avoid property degradation, corrosion resistant to maintain integrity against coolant/chemistry, and reasonably good at heat removal via adequate thermal conductivity to prevent hot spots and dimensional changes.

Step-by-Step Solution:

Verification / Alternative check:

Historical choices—graphite (good thermal properties, radiation moderated design), heavy water (chemically managed systems), and pressurized water reactors (materials selection and chemistry control)—show these requirements in practice.

Why Other Options Are Wrong:

Choosing only one property ignores other critical constraints; failures often arise from corrosion or radiation damage rather than neutronics alone.

Common Pitfalls:

Assuming neutronics alone determines suitability; engineering survivability is equally decisive.

Final Answer:

all of these