What is applications of radioactivity?

Q: What is applications of radioactivity?

Applications of Radioactivity are the practical uses of radioactive materials and their emissions in medicine, agriculture, industry, research, and energy production. These applications harness alpha, beta, and gamma radiation to solve real-world problems.

Applications of Radioactivity — Chemistry Keypoint

Applications of Radioactivity are the practical uses of radioactive materials and their emissions in medicine, agriculture, industry, research, and energy production. These applications harness alpha, beta, and gamma radiation to solve real-world problems.

Quick Summary

Radioactivity treats cancer and sterilizes medical equipment
Carbon-14 dating helps archaeologists determine the age of ancient artifacts
Industrial uses include detecting metal defects and measuring thickness
Nuclear power plants generate electricity using controlled fission
Food irradiation kills harmful bacteria and extends shelf life

Medical Applications

Cancer Treatment (Radiotherapy)

Radioactive isotopes destroy cancer cells. Cobalt-60 produces strong gamma rays that target tumors. Doctors at Lagos University Teaching Hospital (LUTH) and other Nigerian hospitals use radiotherapy machines to treat breast cancer, cervical cancer, and other malignancies.

The radiation damages the DNA of cancer cells, stopping them from growing and dividing. Because cancer cells divide faster than normal cells, they’re more sensitive to radiation. Doctors carefully calculate doses to kill cancer cells while sparing healthy tissue.

Common isotopes used:

Cobalt-60 (external beam therapy)
Iodine-131 (thyroid cancer)
Phosphorus-32 (blood disorders)
Radium-226 (implanted near tumors)

Medical Diagnosis

Radioactive tracers help doctors see inside your body without surgery. A tracer is a radioactive substance that emits gamma rays doctors can detect with special cameras.

For example, technetium-99m is injected into the bloodstream. It travels to organs like the heart, brain, or bones. A gamma camera takes pictures showing how blood flows or where bones are damaged. The isotope has a short half-life (6 hours), so it doesn’t stay radioactive for long.

PET scans (Positron Emission Tomography) use isotopes like fluorine-18 to detect cancer, brain disorders, and heart disease. The isotope concentrates in active tissues, creating bright spots on the scan.

Sterilization of Medical Equipment

Gamma rays from cobalt-60 kill all bacteria, viruses, and fungi on surgical instruments, syringes, bandages, and gloves. This is called gamma sterilization.

NAFDAC approves this method for medical products in Nigeria. The radiation penetrates sealed packages, so equipment stays sterile until opened. Unlike heat sterilization, it doesn’t damage plastic or rubber items.

Agricultural Applications

Pest Control

Scientists use the Sterile Insect Technique (SIT) to control pests. Male insects are exposed to gamma radiation, which makes them sterile (unable to reproduce). These sterile males are released into the wild, where they mate with females. The females lay eggs that never hatch.

Nigeria’s Institute for Agricultural Research uses this to fight tsetse flies that spread sleeping sickness. It’s also effective against fruit flies that damage mango and orange crops.

Food Preservation

Irradiating food kills bacteria like Salmonella and E. coli, parasites, and insects. It also slows ripening, so fruits and vegetables last longer.

At Ikeja markets, yam tubers often sprout quickly. Irradiation prevents sprouting, extending storage time by months. Irradiated food doesn’t become radioactive—it’s like how standing in sunlight doesn’t make you glow.

Benefits include:

Reduces food poisoning risks
Decreases post-harvest losses (important in Nigeria where 40% of food spoils)
Eliminates need for chemical preservatives
No change in taste or nutritional value

Mutation Breeding

Exposing seeds to controlled radiation creates mutations. Most mutations are harmful, but occasionally one produces a better plant—higher yield, disease resistance, or drought tolerance.

Scientists at the Nigerian Institute for Nuclear Research and Development (NINERD) have developed improved cassava and rice varieties using this technique.

Industrial Applications

Thickness Gauging

Factories use radioactive sources to measure the thickness of paper, plastic sheets, or metal foils as they’re manufactured. The source emits beta particles on one side of the moving sheet. A detector on the other side measures how many particles pass through.

If the material gets thicker, fewer particles penetrate, and the detector signals machines to adjust the rollers. This ensures uniform thickness—critical for producing quality aluminum foil or PVC pipes.

Detecting Defects in Metals

Radiography uses gamma rays to check welds and metal parts for cracks, voids, or weak spots. It’s like an X-ray for machines.

The Nigerian National Petroleum Corporation (NNPC) uses this to inspect oil pipelines. Gamma rays from iridium-192 pass through the pipe and expose photographic film on the other side. Cracks show up as dark lines because more radiation passes through gaps.

This prevents pipeline bursts that cause oil spills and environmental damage.

Leak Detection

To find leaks in underground pipes, engineers inject a radioactive tracer into the water flow. They use detectors on the ground to track where the tracer appears. A sudden increase in radiation shows where water is escaping.

Lagos Water Corporation could use this to find leaks wasting millions of liters daily.

Smoke Detectors

Many smoke alarms contain americium-241, which emits alpha particles. These particles ionize air molecules between two metal plates, creating a tiny electric current.

When smoke enters the detector, it absorbs the alpha particles, reducing the current. This triggers the alarm. The amount of radioactive material is extremely small and safe.

Archaeological and Geological Applications

Carbon-14 Dating

Archaeologists determine the age of ancient objects using carbon-14, a radioactive isotope. All living things absorb carbon-14 from the atmosphere. When they die, the carbon-14 decays with a half-life of 5,730 years.

By measuring how much carbon-14 remains in wood, bones, or cloth, scientists calculate how long ago the organism died. This method works for objects up to 50,000 years old.

Nigerian archaeologists used carbon-14 dating to confirm that the Nok terracotta sculptures are over 2,000 years old, proving Nigeria’s ancient civilization.

Geological Dating

For rocks and minerals millions of years old, scientists use isotopes with longer half-lives:

Uranium-238 (half-life: 4.5 billion years) for Earth’s oldest rocks
Potassium-40 (half-life: 1.3 billion years) for volcanic rocks
Rubidium-87 (half-life: 49 billion years) for meteorites

Energy Production

Nuclear Power Plants

Nuclear fission of uranium-235 produces enormous heat. This heat boils water, creating steam that spins turbines connected to generators.

One kilogram of uranium-235 produces as much energy as burning 3 million kilograms of coal. Nuclear plants don’t emit carbon dioxide, so they help fight climate change.

Advantages:

Produces massive amounts of electricity from small fuel quantities
No greenhouse gas emissions during operation
Reliable baseload power (runs 24/7)
Low operating costs once built

Disadvantages:

Radioactive waste remains dangerous for thousands of years
High construction and decommissioning costs
Risk of accidents (Chernobyl, Fukushima)
Potential for weapons material diversion

Radioisotope Thermoelectric Generators (RTGs)

Space probes like Voyager use RTGs because solar panels don’t work far from the Sun. These devices convert heat from radioactive decay directly into electricity. Plutonium-238 is commonly used.

RTGs also power remote weather stations, lighthouses, and pacemakers (older models).

Military Applications

Nuclear Weapons

Atomic bombs use uncontrolled fission of uranium-235 or plutonium-239. The sudden release of energy creates a massive explosion, intense heat, and deadly radiation.

Hydrogen bombs use fusion reactions, combining hydrogen isotopes at extreme temperatures initiated by a fission bomb. These are far more destructive.

The international community works to prevent nuclear weapons spread through the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which Nigeria signed.

Comparison of Medical vs Industrial Uses

Aspect	Medical Applications	Industrial Applications
Main Purpose	Diagnose and treat diseases	Quality control and testing
Isotopes Used	Cobalt-60, Technetium-99m, Iodine-131	Iridium-192, Americium-241, Cobalt-60
Radiation Type	Mainly gamma (deep penetration)	Beta (thickness), Gamma (defects), Alpha (smoke)
Safety Concerns	Patient exposure carefully controlled	Worker exposure minimized with shielding
Half-Life Preference	Short (hours to days) for diagnostics	Long (years) for continuous use
Benefit	Saves lives, improves health	Improves product quality, prevents accidents

Common Exam Mistakes

WAEC examiners report these frequent errors:

Vague answers: Writing “used in medicine” isn’t enough. Specify whether it’s for treatment (killing cancer cells) or diagnosis (imaging organs).
Confusing sterilization with preservation: Sterilization kills germs on equipment; food preservation prevents spoilage. They’re different applications.
Not mentioning specific isotopes: Good answers name isotopes like cobalt-60, carbon-14, or iodine-131 and explain why they’re suitable.
Ignoring disadvantages: When asked about nuclear power, students forget to mention radioactive waste disposal problems or accident risks.
Mixing up carbon dating and other dating methods: Carbon-14 is only for organic materials up to 50,000 years old. Use uranium-238 for rocks millions of years old.
Claiming irradiated food becomes radioactive: This is false. Food irradiation doesn’t make food emit radiation.

Practice Questions

Multiple Choice

1. Which radioactive isotope is commonly used to treat thyroid cancer?

(a) Cobalt-60
(b) Iodine-131 ✓
(c) Carbon-14
(d) Uranium-235

2. Carbon-14 dating is used to determine the age of:

(a) Rocks and minerals
(b) Volcanic lava
(c) Ancient organic materials ✓
(d) Metal artifacts

3. In industrial radiography, gamma rays are used to:

(a) Measure liquid levels
(b) Detect cracks and defects in metals ✓
(c) Sterilize equipment
(d) Power machinery

4. The Sterile Insect Technique (SIT) uses radiation to:

(a) Kill insects directly
(b) Make male insects unable to reproduce ✓
(c) Increase crop yield
(d) Preserve harvested crops

Essay Questions

5. (a) List three applications of radioactivity in medicine. (3 marks)

(b) Explain how cobalt-60 is used in cancer treatment. (4 marks)

Total: 9 marks

Exam tip: For part (a), be specific: “cancer treatment” is better than just “medicine.” For part (b), explain that gamma rays damage cancer cell DNA, preventing growth.

6. (a) Describe how carbon-14 dating works. (5 marks)

(b) Explain why carbon-14 dating cannot be used for rocks millions of years old. (3 marks)

Total: 10 marks

Exam tip: Mention the half-life of carbon-14 (5,730 years) and calculate how much would remain after millions of years (essentially zero). Suggest uranium-238 dating for old rocks.

7. (a) State three industrial applications of radioactivity. (3 marks)

(b) Explain how radiation is used to detect leaks in underground pipes. (4 marks)

Total: 11 marks

Exam tip: For part (c), advantages include high energy output and no CO₂ emissions. Disadvantages include radioactive waste and accident risks.

8. A WAEC 2002 question asked:

(a) List three applications of radioactivity in different fields. (3 marks)

(b) Explain the difference between nuclear fission and ordinary chemical reactions involving electron loss. (4 marks)