Applications of nuclear reactors: Identify which listed application is not feasible for a reactor (practical perspective).

Introduction / Context:
Nuclear reactors serve multiple roles beyond electricity generation. They are sources of neutrons, heat, and specific radionuclides. The question asks which of the listed uses is not possible; recognizing real-world reactor applications is key.

Given Data / Assumptions:

• Research reactors routinely produce radioisotopes and neutron beams.
• Naval propulsion reactors power submarines and surface ships.
• We assume standard reactor types (research, power, and naval designs).

Concept / Approach:
Reactors can irradiate targets to produce medical and industrial radioisotopes (e.g., Mo-99, I-131). Research reactors provide high neutron fluxes for beam lines, material studies, and neutron imaging. Naval reactors have been used for decades for marine propulsion in submarines and aircraft carriers. Therefore all listed applications are in fact feasible, so there is no item that a reactor cannot do among the options given.

Step-by-Step Solution:

Verification / Alternative check:
Examples include isotope production at OPAL, BR2, and HFIR; neutron science at ILL and NIST; propulsion in U.S. Navy and others.

Why Other Options Are Wrong:

• Each of (a), (b), (c) accurately describes a real use of reactors.

Common Pitfalls:
Assuming only power generation is a valid use; research and naval reactors are large, long-standing applications.

Final Answer:
None of these.