Final answer:
a) Uranium-235 radionuclides are NOT regulated by the NRC.
Step-by-step explanation:
The Nuclear Regulatory Commission (NRC) primarily regulates radionuclides that are used in various applications, including medical, industrial, and research settings. Uranium-235, however, is primarily regulated by the U.S. Department of Energy (DOE) rather than the NRC. Uranium-235 is a fissile isotope used as fuel in nuclear reactors and is subject to separate regulations due to its significance in the nuclear energy sector.
While Cobalt-60, Technetium-99m, and other radionuclides are regulated by the NRC, uranium-235 falls under the jurisdiction of the DOE, which oversees issues related to nuclear energy production and security. It is crucial to distinguish between different regulatory bodies to ensure proper oversight and compliance with safety standards for each specific radionuclide.
In conclusion, a) the radionuclide that is NOT regulated by the NRC among the given options is Uranium-235. Understanding the regulatory framework for various radionuclides is essential to maintain safety and security in the use of radioactive materials across different industries and applications.