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Q9(a):
Discuss briefly the following:
(a) Radioactive wastes
Solution :
1. Definition and Origin of Radioactive Waste
Radioactive waste is defined as any material containing radionuclides—unstable isotopes that undergo spontaneous nuclear decay, emitting ionizing radiation (alpha, beta, or gamma rays). These wastes are primarily generated as byproducts of nuclear power generation, medical diagnostics, radiotherapy, and nuclear research facilities [Per the Atomic Energy Act and international guidelines by the IAEA].
2. Classification of Radioactive Waste
Radioactive wastes are classified based on their level of radioactivity and half-life:
| Classification | Source | Hazard Potential |
|---|---|---|
| Low-Level Waste (LLW) | Contaminated laboratory equipment, medical gowns, paper. | Low activity; requires short-term isolation. |
| High-Level Waste (HLW) | Spent nuclear fuel rods, concentrated liquid from reprocessing. | Extremely high activity; intense heat generation; long half-lives. |
3. Physiological and Environmental Impact
The primary concern regarding radioactive waste is its lethality to biological systems. Ionizing radiation causes damage via two primary mechanisms:
- Direct Damage: Radiation strikes DNA molecules directly, inducing double-strand breaks that lead to mutations or cell death [By Biological Principles of Radiotoxicity].
- Indirect Damage: Radiation causes the radiolysis of water within cells, creating highly reactive free radicals ($OH^•$, $H^•$) that oxidize cellular components, leading to carcinogenic, mutagenic, and teratogenic effects.
4. Management and Disposal Protocol
Due to the longevity of certain isotopes (e.g., $^{239}Pu$ with a half-life of 24,100 years), current scientific consensus favors the following mitigation strategy:
- Pre-treatment: Volume reduction through compaction or incineration (where applicable) and solidification in glass (vitrification) to prevent leaching.
- Containment: Encapsulation in shielded, corrosion-resistant containers (lead or high-density concrete).
- Deep Geological Disposal: Burial of containers in stable, geologically inactive formations (e.g., deep salt mines or crystalline rock) at depths of $500\text{–}1000$ meters to ensure isolation from the biosphere for millennia [Per Nuclear Regulatory Commission standards].
5. Conceptual Visualization of Radioactive Decay Chain
Final Solution: Radioactive wastes are hazardous byproducts of nuclear operations that emit ionizing radiation capable of damaging biological DNA. Their management requires strict adherence to international safety protocols, specifically vitrification and deep geological sequestration, to isolate radionuclides from the biosphere until they reach safe levels of decay.
More Questions from Class 12 Biology Environmental Issues EXERCISES
- Q1: What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
- Q1: What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
- Q2: List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?
- Q2: List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?
- Q3: Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
- Q3: Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
- Q4: Match the items given in column A and B:
- Q4: Match the items given in column A and B: Column A Column B (a) Catalytic converter (i) Particulate matter (b) Electrostatic precipitator (ii) Carbon monoxide and nitrogen oxides (c) Earmuffs (iii) High noise level (d) Landfills (iv) Solid wastes
- Q5(a): Write critical notes on the following: (a) Eutrophication
- Q5(a): Write critical notes on the following: (a) Eutrophication
- Q5(b): Write critical notes on the following: (b) Biological magnification
- Q5(b): Write critical notes on the following: (b) Biological magnification
- Q5(c): Write critical notes on the following: (c) Groundwater depletion and ways for its replenishment
- Q5(c): Write critical notes on the following: (c) Groundwater depletion and ways for its replenishment
- Q6: Why does ozone hole form over Antarctica? How will enhanced ultraviolet radiation affect us?
- Q6: Why does ozone hole form over Antarctica? How will enhanced ultraviolet radiation affect us?
- Q7: Discuss the role of women and communities in protection and conservation of forests.
- Q7: Discuss the role of women and communities in protection and conservation of forests.
- Q8: What measures, as an individual, would you take to reduce environmental pollution?
- Q8: What measures, as an individual, would you take to reduce environmental pollution?
- Q9(a): Discuss briefly the following: (a) Radioactive wastes
- Q9(b): Discuss briefly the following: (b) Defunct ships and e-wastes
- Q9(b): Discuss briefly the following: (b) Defunct ships and e-wastes
- Q9(c): Discuss briefly the following: (c) Municipal solid wastes
- Q9(c): Discuss briefly the following: (c) Municipal solid wastes
- Q10: What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
- Q10: What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
- Q11(a): Discuss briefly the following: (a) Greenhouse gases
- Q11(a): Discuss briefly the following: (a) Greenhouse gases
- Q11(b): Discuss briefly the following: (b) Catalytic converter
- Q11(b): Discuss briefly the following: (b) Catalytic converter
- Q11(c): Discuss briefly the following: (c) Ultraviolet B
- Q11(c): Discuss briefly the following: (c) Ultraviolet B
CBSE Solutions for Class 12 Biology Environmental Issues
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
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