Radioactive Waste: Sources and Half-life

Radioactive waste is material -- solid, liquid or gaseous -- that contains radioactive isotopes (unstable atomic nuclei that spontaneously emit ionising radiation as they decay toward a more stable form) at concentrations or activities considered too high for the material to be released into the environment without special handling. Unlike ordinary chemical waste, radioactive waste cannot be neutralised, broken down or otherwise made safe through chemical treatment; the only way its hazard genuinely decreases over time is through the natural process of radioactive decay itself, which proceeds at a fixed rate for any given isotope regardless of the temperature, pressure or chemical environment it is kept in.

The major sources of radioactive waste in a country like India reflect the range of peaceful applications of nuclear and radioactive technology. Nuclear power plants are the single largest source by volume and by overall radioactivity, generating spent nuclear fuel once it can no longer efficiently sustain the chain reaction inside a reactor, along with contaminated equipment, protective clothing and other materials used during reactor operation and maintenance. Medical use of radioisotopes is a second major source: hospitals use radioactive material for diagnostic imaging (certain scanning procedures use short-lived radioactive tracers) and for radiotherapy in cancer treatment, generating comparatively small volumes of waste but requiring careful handling given how widely distributed hospitals are compared with the small number of nuclear power plants. Research laboratories and universities that use radioisotopes for scientific studies, and various industrial applications (such as radiography for inspecting welds, or certain types of measuring and gauging instruments that use sealed radioactive sources), together form a third significant category of source. …