Question 14 of 19: Managing Liquid Radioactive Wastes

Question 14: Managing Liquid Radioactive Wastes (3 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

In Canada, liquid radioactive waste is regulated by the Canadian Nuclear Safety Commission (CNSC) under the Nuclear Safety and Control Act, and management depends on the isotope's activity level and half-life. Common strategies are: (1) decay storage — hold short-half-life waste (common in medical/laboratory use) in shielded storage until its activity decays to background/exempt levels (a common rule of thumb is roughly ten half-lives), after which it can be managed as ordinary waste; (2) treatment to concentrate and reduce volume — ion exchange, evaporation or chemical precipitation to transfer the radioactivity into a small solid/sludge fraction for licensed disposal, releasing a decontaminated liquid; (3) controlled, licensed discharge — only within CNSC-authorized concentration limits to a sanitary sewer, where explicitly permitted; and (4) long-term managed storage or disposal at a licensed facility for higher-activity or long-half-life waste. Throughout, full characterization, licensing and chain-of-custody documentation are mandatory — radioactive liquid waste is never discharged to the environment without prior authorization.