================================== DOCUMENT 9: SESSION 9 (S9) ================================== POLLUTION ABATEMENT (21CHO105T) Unit 2 - Session 9 I. MULTIPLE CHOICE QUESTIONS (MCQs) 1. Vitrification of nuclear waste involves: ● Answer: C. Immobilizing waste in glass ● Explanation: Vitrification is a high-temperature immobilization process where liquid high-level radioactive waste is melted together with glass-forming materials into stable borosilicate glass. 2. The main purpose of vitrification is to: ● Answer: C. Prevent migration of radioactive materials ● Explanation: Vitrification locks radioactive isotopes inside a durable, chemically resistant glass matrix, preventing leaching and migration into the environment. 3. Interim storage of nuclear waste is required to: ● Answer: B. Allow radioactive decay and cooling ● Explanation: Spent nuclear fuel and high-level waste require interim cooling pools or dry casks for decades to allow short-lived radioactive isotopes to decay and thermal heat loads to decrease. 4. Environmental monitoring in nuclear waste management includes: ● Answer: B. Monitoring radiation levels and groundwater quality ● Explanation: Comprehensive environmental surveillance programs continuously test ambient radiation levels, air, soil, and nearby groundwater sources for radioactive contamination. 5. Groundwater protection is important in nuclear waste disposal because: ● Answer: B. Radioactive leakage can contaminate drinking water ● Explanation: Deep geological repositories and containment barriers protect groundwater systems to prevent any leached radionuclides from entering aquatic food chains and drinking water supplies. II. SHORT ANSWER QUESTIONS 1. What are the types of nuclear waste? ● Answer: 1. Low-Level Waste (LLW): Contaminated paper, rags, tools, and clothing with low radioactivity levels. 2. Intermediate-Level Waste (ILW): Resins, chemical sludges, and reactor components requiring shielding. 3. High-Level Waste (HLW): Spent nuclear fuel and liquid byproducts from reprocessing, characterized by high radioactivity and long heat-generation half-lives. 2. Why is safety important in nuclear waste management? ● Answer: Nuclear waste emits ionizing radiation that can cause severe biological damage, genetic mutations, and cancer in humans, alongside long-term ecological destruction. Strict containment and safety protocols are vital to prevent radiation leaks over thousands of years. III. LONG ANSWER QUESTION 1. Describe the processing and disposal methods of nuclear waste. ● Answer: 1. Volume Reduction and Conditioning ● Compact & Incineration: Compacting low-level solid waste and incinerating combustible contaminated materials to reduce overall volume. ● Liquid Treatment: Precipitation, ion exchange, and evaporation to concentrate radioactive isotopes from aqueous waste streams. 2. Vitrification (Immobilization) ● High-level liquid radioactive waste is combined with glass frit and heated in high-temperature ceramic melters to form stable borosilicate glass blocks. This traps radioactive atoms within an inert, leach-resistant matrix. 3. Interim Storage ● Placing conditioned waste in secure, monitored interim facilities—such as water-filled cooling pools or robust concrete dry casks—for decades to allow thermal cooling and radioactive decay. 4. Final Disposal (Deep Geological Repositories) ● Permanent disposal of high-level and long-lived waste deep underground (500 meters or more) in stable rock formations (granite, clay, or salt domes). Multi-barrier systems (waste form, corrosion-resistant canisters, bentonite clay buffers, and host rock) isolate the waste from the biosphere permanently.