Purpose of the neutron reflector in reactor design State the primary function of installing a reflector region around the active reactor core.

Introduction / Context:A reflector region surrounds the active core to improve neutron economy. By scattering outward-moving neutrons back towards the fuel, a reflector reduces leakage and can increase multiplication, flatten flux, and allow smaller cores for the same reactivity.

Given Data / Assumptions:

• A reflector is made of low-absorption, good-scattering material (graphite, beryllium, water, or steel depending on design).
• Steady-state operation is considered.
• The statement claims the reflector is used to reflect neutrons back into the active core.

Concept / Approach:Neutron transport theory shows that adding a region with favorable scattering length and low capture cross section increases the probability that leaking neutrons re-enter the core. This produces the well-known “reflector savings” in criticality calculations, effectively reducing the required core size or fuel loading.

Step-by-Step Solution:Identify desired effect: reduce leakage (neutrons escaping boundary).Add reflector with appropriate properties → more back-scatter and moderation.Result: more neutrons return to the core and contribute to fissions.

Verification / Alternative check:Flux measurements show higher peripheral flux and improved core reactivity with reflectors, consistent with design calculations.

Why Other Options Are Wrong:

• “False” or restrictive conditions ignore that reflectors are standard across many reactor types, not only fast or heavy-water designs.
• “Absorb all neutrons” contradicts the reflector selection principle of low absorption.

Common Pitfalls:Assuming any material placed outside the core acts as a reflector; material selection is critical to achieve reflection rather than absorption.

Final Answer:True