Interview Questions for Nuclear Decay Processes

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. There are three main types: alpha, beta, and gamma decay. Each involves different particles and energies.

• Alpha Decay: Emission of an alpha particle (two protons and two neutrons, essentially a helium nucleus).
• Beta Decay: Emission of a beta particle (an electron or a positron) and a neutrino or antineutrino.
• Gamma Decay: Emission of a gamma ray (a high-energy photon).

The type of decay a nucleus undergoes depends on the specific imbalance of protons and neutrons within its nucleus, aiming for a more stable configuration.

Alpha decay occurs when a nucleus is too large and unstable. To achieve stability, it ejects an alpha particle, reducing its atomic number by 2 and its mass number by 4. Think of it like shedding excess weight to become more balanced. For example, Uranium-238 (²³⁸U) decays into Thorium-234 (²³⁴Th) via alpha decay.

The energy released in alpha decay is primarily kinetic energy carried away by the alpha particle. This energy is calculated using Einstein’s famous equation, E=mc², where the mass difference between the parent and daughter nuclei (the mass defect) is converted into energy. The energy is typically on the order of several MeV (Mega-electron volts).

Beta decay involves the conversion of a neutron into a proton (beta-minus decay) or a proton into a neutron (beta-plus decay). This process aims to adjust the neutron-proton ratio for stability.

• Beta-minus (β^–) decay: A neutron transforms into a proton, emitting an electron (β^– particle) and an antineutrino. The atomic number increases by 1, while the mass number remains the same. Example: Carbon-14 (¹⁴C) decays into Nitrogen-14 (¹⁴N).
• Beta-plus (β⁺) decay: A proton transforms into a neutron, emitting a positron (β⁺ particle) and a neutrino. The atomic number decreases by 1, and the mass number stays constant. Example: Fluorine-18 (¹⁸F) decays into Oxygen-18 (¹⁸O).

The energy released in beta decay is shared between the beta particle and the neutrino. The energy spectrum of beta particles is continuous, reflecting this energy sharing.

Gamma decay is different from alpha and beta decay because it doesn’t involve a change in the number of protons or neutrons. Instead, it’s the emission of a gamma ray (high-energy photon) by an excited nucleus. Imagine the nucleus as a ball that’s been energized and needs to release that extra energy; the gamma ray is how it does so.

Alpha and beta decay often leave the nucleus in an excited state. Gamma decay is the subsequent release of this excess energy as a gamma ray, returning the nucleus to its ground state. It doesn’t change the atomic number or mass number, simply reducing the energy of the nucleus. Gamma rays have very high energy and penetrate deeply, posing a significant radiation hazard.

The half-life of a radioactive isotope is the time it takes for half of the atoms in a sample to decay. This is a crucial concept because it indicates how quickly a radioactive material will lose its radioactivity. It’s a constant characteristic for a given isotope and doesn’t depend on the amount of the material or other external factors (except in very rare cases involving extreme conditions).

For instance, if a substance has a half-life of 10 years, after 10 years, half of the original radioactive atoms will have decayed. After another 10 years (20 years total), half of the remaining atoms will have decayed, leaving only a quarter of the original amount, and so on. Half-life is used extensively in radiometric dating, nuclear medicine, and radiation safety calculations.

Determining the half-life of a radioactive isotope involves measuring the decay rate of a sample over time. Scientists track the number of radioactive atoms remaining and plot this data on a graph. The half-life can be calculated from this graph by determining the time it takes for the number of radioactive atoms to decrease by half. Sophisticated instruments like Geiger counters and scintillation detectors are used to measure the decay rate accurately. The statistical nature of decay requires large sample sizes to ensure reliable results.

Advanced techniques involving nuclear spectroscopy further refine the process. The precision of half-life measurement varies depending on the isotope and the available instrumentation, with some isotopes exhibiting half-lives that are extremely difficult to measure precisely due to their exceptionally long or short decay times.

A radioactive decay chain is a series of radioactive decays that an unstable nucleus undergoes until it transforms into a stable nuclide (one that doesn’t decay). Each decay step in the chain involves a different type of decay (alpha, beta, or gamma) and results in a new, often still unstable, daughter nucleus. This process continues until a stable nucleus is reached. For example, the uranium-238 decay chain involves a series of alpha and beta decays, eventually resulting in stable lead-206. Understanding these chains is essential in various applications like geological dating and nuclear waste management.

Decay chains are often visualized as diagrams showing the sequence of decays and the resulting isotopes. These diagrams are important for understanding the environmental impact of radioactive substances and predicting the evolution of radioactive waste over time.

Nuclear radiation encompasses several types of energetic emissions from unstable atomic nuclei. These emissions differ significantly in their penetrating power, which dictates their interaction with matter.

• Alpha (α) particles: These are essentially helium nuclei (2 protons and 2 neutrons), carrying a +2 charge. They are relatively massive and slow-moving, making them easily stopped by a sheet of paper or even a few centimeters of air. Their high ionization power means they cause significant damage along their short path.
• Beta (β) particles: These are high-energy electrons or positrons (anti-electrons). They are much lighter and faster than alpha particles, thus exhibiting greater penetration. A thin sheet of aluminum can typically stop beta particles. They also cause ionization, but less intensely than alpha particles, allowing them to travel further.
• Gamma (γ) rays: These are high-energy electromagnetic radiation, similar to X-rays but with shorter wavelengths and higher energies. They are highly penetrating, requiring thick layers of lead or concrete for substantial shielding. They interact with matter through various processes, primarily photoelectric effect and Compton scattering.
• Neutron radiation: Neutrons are electrically neutral particles and thus interact differently than charged particles. They penetrate deeply into materials, requiring substantial amounts of shielding, such as water or concrete, for effective attenuation. They cause damage primarily through nuclear reactions rather than direct ionization.

Imagine it like this: Alpha particles are like a bowling ball – big, slow, and easily stopped. Beta particles are like a baseball – smaller, faster, and needing a bit more effort to stop. Gamma rays are like tiny bullets – small, incredibly fast, and requiring heavy armor to block them. Neutrons are like invisible projectiles, powerful but hard to detect until they strike something.

Radioactive equilibrium describes a state where the activity of a radioactive daughter nuclide is equal to the activity of its parent nuclide. This doesn’t mean the amounts are equal, only the rate of decay. It’s a dynamic balance where the daughter is being produced at the same rate it’s decaying.

This equilibrium is achieved when the half-life of the parent nuclide is significantly longer than that of the daughter nuclide (by a factor of at least 10). In such cases, the daughter nuclide’s activity quickly reaches a steady state, mirroring the parent’s activity.

For example, consider the decay chain of Uranium-238 to Lead-206. Many intermediate daughter products exist with varying half-lives. However, if we consider a specific daughter product with a much shorter half-life than U-238, it will eventually reach secular equilibrium where its activity matches that of U-238. It’s important to note that transient equilibrium also exists, where the half-life of the parent is shorter than the daughter, resulting in a temporary balance of activities before the daughter also decays.

The activity of a radioactive sample, typically measured in Becquerels (Bq) or Curies (Ci), decreases exponentially over time. The half-life (t_1/2) is the time it takes for half of the radioactive atoms to decay. We can use the following formula to calculate the activity (A) at a time (t) given the initial activity (A₀) and half-life:

Where:

• A is the activity at time t
• A₀ is the initial activity
• t is the elapsed time
• t_1/2 is the half-life

Example: If a sample has an initial activity of 1000 Bq and a half-life of 10 days, what will its activity be after 20 days?

Therefore, the activity after 20 days will be 250 Bq.

Radioactive decay finds numerous critical applications in medicine, primarily in diagnostics and therapeutics.

• Diagnostics: Radioactive tracers, such as Technetium-99m, are used in medical imaging techniques like SPECT (Single-Photon Emission Computed Tomography) and PET (Positron Emission Tomography). These tracers emit gamma rays that can be detected externally, allowing visualization of internal organs and physiological processes. This helps diagnose various diseases including heart conditions, cancers, and bone disorders.
• Therapeutics: Radioactive isotopes, such as Iodine-131, are utilized in radiotherapy to target and destroy cancerous cells. Brachytherapy, for instance, involves placing radioactive sources directly into or near tumors. Targeted alpha-therapy is a newer approach which utilizes alpha emitting radionuclides conjugated to tumour specific ligands for highly selective treatment. Other techniques use external beam radiation, but the decay process is central to their effectiveness.

The choice of isotope depends on factors like the half-life (short half-life for diagnostics to minimize radiation exposure, longer half-life for therapy), the type of radiation emitted (gamma for imaging, beta or alpha for therapy), and its biodistribution within the body.

Industrial gauging leverages radioactive sources to measure various properties of materials and processes non-destructively. This is crucial for quality control and process optimization.

• Thickness Gauging: Beta emitters are commonly used to measure the thickness of materials like paper, plastic film, and metal sheets. The amount of radiation that passes through the material is inversely proportional to its thickness.
• Level Gauging: Gamma emitters with high penetration power are employed to determine the level of liquids or solids in containers or storage tanks. The attenuation of the gamma rays as they pass through the material indicates the level.
• Density Gauging: The attenuation of gamma or X-rays provides information on the density of materials like soil or concrete, crucial in construction and civil engineering.
• Moisture Gauging: Neutron sources are used to measure the moisture content in various materials, such as soil or concrete. Neutrons interact with hydrogen atoms in water, generating signals that can be detected and analyzed.

The choice of radioactive source depends on the material’s characteristics and the desired measurement accuracy. Safety regulations are paramount as these methods involve handling radioactive materials.

Radioactive decay plays a vital role in environmental monitoring, helping assess the presence and movement of pollutants and contaminants.

• Tracing Pollutants: Radioactive tracers can track the movement of pollutants in water bodies, soil, or air. This helps understand how pollutants disperse and potentially mitigate their impact.
• Monitoring Radioactive Contamination: Following nuclear accidents or leaks from nuclear facilities, radioactive isotopes are used to map the extent of contamination and guide cleanup efforts.
• Dating Sediments and Groundwater: Radioactive isotopes like Carbon-14 and other naturally occurring radionuclides are used to determine the age of sediments and groundwater, providing insights into geological processes and hydrological systems.

Environmental monitoring using radioactive isotopes necessitates strict safety protocols to minimize exposure to radiation and ensure accurate measurements.

Radioactive isotopes serve as natural clocks, allowing us to estimate the age of ancient artifacts, geological formations, and other materials. Carbon-14 dating is a prime example.

Carbon-14 is a radioactive isotope of carbon formed in the upper atmosphere by cosmic ray interactions. Living organisms continuously intake Carbon-14, maintaining a relatively constant ratio with stable Carbon-12. Upon death, the intake stops, and the Carbon-14 begins to decay with a half-life of approximately 5,730 years.

By measuring the remaining Carbon-14 to Carbon-12 ratio in a sample (e.g., a piece of wood or bone), we can estimate how long ago the organism died. Other dating methods utilize different radioactive isotopes with longer half-lives to date older materials. Uranium-Lead dating, for example, is used to date geological samples billions of years old.

The accuracy of these dating techniques depends on several factors, including the initial concentration of the isotope, the stability of the decay rate, and potential contamination of the sample.

Nuclear fission is the splitting of a heavy atomic nucleus into two or more lighter nuclei, releasing a tremendous amount of energy. Think of it like breaking a giant glass ball into smaller pieces – the energy released comes from the rearrangement of the subatomic particles. This process is directly related to radioactive decay because many fission products are themselves radioactive, undergoing further decay to reach a stable state. For instance, the fission of uranium-235 often produces radioactive isotopes like strontium-90 and cesium-137, which then decay through beta emission and gamma decay, respectively. The initial fission event triggers a chain reaction, further emphasizing the intertwined nature of fission and decay. This chain reaction is harnessed in nuclear power plants to generate electricity, while uncontrolled chain reactions are the basis of nuclear weapons.

Nuclear fusion is the opposite of fission; it involves the combining of two light atomic nuclei to form a heavier nucleus, also releasing a vast amount of energy. Imagine merging two small water droplets to form a larger one – the excess energy is released because the mass of the combined nucleus is slightly less than the sum of the masses of the original nuclei (mass-energy equivalence, E=mc²). While fusion reactions in stars produce many radioactive isotopes, the relationship to radioactive decay isn’t as direct as with fission. Fusion reactions themselves don’t typically produce radioactive byproducts in the same way that fission does. However, some fusion products may be unstable and undergo radioactive decay. For example, some isotopes of helium produced in fusion reactions might be radioactive but their decay is generally less problematic compared to fission products.

Radioactivity is detected and measured using various instruments that respond to the ionizing radiation emitted by radioactive materials. These instruments include:

• Geiger-Müller counters: These detect ionizing radiation by measuring the ionization it produces in a gas-filled tube. They’re widely used for quick radiation surveys.
• Scintillation detectors: These use materials that emit light when struck by ionizing radiation. The light pulses are then counted, providing a measure of radiation intensity. These are very sensitive and can differentiate between different types of radiation.
• Semiconductor detectors: These utilize semiconductors that generate an electrical signal upon interaction with ionizing radiation. They offer high energy resolution, making them suitable for precise measurements of radiation energy.
• Film badges and thermoluminescent dosimeters (TLDs): These passive detectors measure accumulated radiation dose over time. Film badges use photographic film that darkens upon exposure, while TLDs store energy from radiation and release it as light when heated, allowing for quantification of the dose.

The choice of instrument depends on the type and energy of the radiation, the required sensitivity, and the application. For example, a Geiger counter might suffice for a quick check of radiation levels, while a semiconductor detector would be needed for precise spectral analysis.

Handling radioactive materials requires strict adherence to safety protocols to minimize exposure. Key precautions include:

• Time minimization: Limit the time spent near radioactive sources.
• Distance maximization: Increase the distance from the source; radiation intensity decreases rapidly with distance.
• Shielding: Use appropriate shielding materials (lead, concrete, etc.) to absorb radiation.
• Containment: Radioactive materials should be contained in sealed containers to prevent leakage.
• Personal protective equipment (PPE): Use gloves, lab coats, respirators, and other protective equipment.
• Monitoring: Regularly monitor radiation levels using appropriate instruments.
• Proper training: Personnel must receive adequate training in radiation safety procedures.
• Waste disposal: Radioactive waste must be handled and disposed of according to regulations.

Failure to follow these precautions can lead to serious health consequences, ranging from mild skin irritation to severe radiation sickness and even death.

Ionizing radiation, due to its ability to strip electrons from atoms, can damage biological molecules such as DNA. The effects depend on the dose, type of radiation, and the exposed tissue. Low doses might have no immediate effects, but they can increase the risk of cancer later in life. Higher doses can cause acute radiation sickness, characterized by nausea, vomiting, fatigue, and potentially organ damage. Severe exposure can be fatal. The damage to DNA can lead to mutations, cell death, or uncontrolled cell growth (cancer). Different types of radiation have different relative biological effectiveness (RBE), meaning some types of radiation are more damaging per unit of dose than others. For example, alpha particles have a higher RBE than beta particles or gamma rays.

Radiation shielding reduces exposure to ionizing radiation by absorbing or attenuating the radiation. The choice of shielding material depends on the type and energy of the radiation.

• Lead: Effective at shielding against gamma rays and X-rays, commonly used in medical imaging and industrial applications.
• Concrete: Relatively inexpensive and effective for shielding against gamma rays and neutrons, commonly used in nuclear power plants and research facilities.
• Water: Effective against neutrons and gamma rays, often used in research reactors as a biological shield.
• Steel: Provides shielding against beta particles and lower energy gamma rays.

The thickness of the shielding material is crucial; thicker shields provide greater attenuation. The design of shielding structures often involves complex calculations to ensure adequate protection.

Radioactive waste management is a critical aspect of nuclear safety. It involves a multi-stage process:

• Waste characterization: Determining the type, quantity, and radioactivity of the waste.
• Waste treatment: Processing the waste to reduce its volume and radioactivity. This may involve techniques like solidification, incineration, or chemical separation.
• Waste storage: Temporarily storing the waste in facilities designed to prevent leakage and protect the environment. This can range from simple storage in drums to highly engineered repositories.
• Waste disposal: Ultimately disposing of the waste in a way that minimizes the risk to human health and the environment. This might involve deep geological repositories for high-level waste or shallow land burial for low-level waste.

The approach to waste management varies depending on the type of waste. High-level waste (from nuclear reactors) requires long-term, highly secure storage and disposal, while low-level waste can be disposed of using less stringent methods. International regulations and national policies guide the safe management of radioactive waste.

Regulations governing radioactive materials are incredibly stringent and vary slightly between countries, but the core principles remain consistent. The overarching goal is to protect both workers and the public from the harmful effects of ionizing radiation. These regulations typically cover:

• Licensing and Permits: Organizations must obtain licenses to possess, use, and dispose of radioactive materials. The licensing process involves rigorous safety assessments and demonstrations of competency.
• Transportation: Strict rules govern the transport of radioactive materials, including packaging requirements, route planning, and emergency response protocols. This ensures that materials are safely transported without risk to the public or environment.
• Storage and Handling: Specific procedures must be followed for storage, handling, and use of radioactive materials, emphasizing radiation shielding, containment, and monitoring. Regular safety inspections are common.
• Waste Management: Regulations detail procedures for the safe disposal and management of radioactive waste, taking into account the different levels of radioactivity and the potential long-term risks. This often involves specialized facilities and long-term storage solutions.
• Emergency Preparedness: Facilities handling radioactive materials must have detailed emergency plans in place to address accidents, spills, or other unforeseen events. These plans involve evacuation procedures, radiation monitoring, and medical response.
• Monitoring and Reporting: Regular monitoring of radiation levels is mandatory, along with reporting requirements to regulatory bodies. This ensures that exposure levels remain within acceptable limits and that any incidents are promptly addressed. Examples include detailed record-keeping of radioactive material inventory and personnel dosimetry reports.

Enforcement of these regulations is crucial and involves regular inspections and penalties for non-compliance. The specific regulations are often detailed in national legislation and international agreements like those from the IAEA (International Atomic Energy Agency).

Radiation detectors are essential tools for measuring ionizing radiation. Different detectors utilize varying principles to detect and quantify radiation:

• Geiger-Müller (GM) Counter: This is a relatively simple and robust detector commonly used for detecting alpha, beta, and gamma radiation. It operates based on gas ionization. Incoming radiation ionizes gas molecules within a tube, creating a cascade of ions that generates a measurable electrical pulse. The number of pulses is proportional to the radiation intensity. GM counters are relatively inexpensive and easy to use, making them suitable for various applications, from radiation surveys to monitoring environmental radioactivity.
• Scintillation Detector: These detectors utilize a scintillating material that emits light photons when struck by ionizing radiation. The light is then detected by a photomultiplier tube (PMT), which converts the light into an electrical signal. Scintillation detectors offer better energy resolution than GM counters, allowing for identification of the type and energy of radiation. They are used in a wide range of applications, including medical imaging (PET scans), nuclear physics experiments, and industrial radiation monitoring.
• Semiconductor Detectors: These detectors utilize semiconductor materials (e.g., silicon, germanium) that generate electron-hole pairs upon interaction with radiation. The number of pairs is proportional to the energy deposited by the radiation. Semiconductor detectors provide excellent energy resolution and are widely used in various scientific and industrial applications, including high-resolution spectroscopy and x-ray analysis.
• Ionization Chambers: These detectors measure the ionization current produced by radiation in a gas-filled chamber. They are often used for high-dose-rate measurements, such as those encountered near reactors or in radiation therapy machines. They are usually less sensitive than other types but provide a more stable and linear response over a wider range of radiation intensities.

The choice of detector depends on the specific application and the type and energy of the radiation being measured. Factors such as sensitivity, energy resolution, and cost all play a role in selecting the appropriate detector.

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique that exploits the magnetic properties of atomic nuclei to obtain information about molecular structure and dynamics. It’s based on the principle that many atomic nuclei possess a property called spin, which gives them a magnetic moment. When placed in a strong external magnetic field, these nuclei can align themselves either parallel or antiparallel to the field. The energy difference between these two states is directly proportional to the strength of the magnetic field. By applying radiofrequency (RF) pulses, we can induce transitions between these energy states.

The key to NMR lies in the fact that the magnetic field experienced by a nucleus is influenced by its local electronic environment. Electrons shield the nucleus from the external magnetic field, and this shielding varies depending on the chemical bonds and surrounding atoms. This leads to slight variations in the resonance frequency of different nuclei in a molecule, a phenomenon known as chemical shift. By analyzing the chemical shifts and other NMR parameters (e.g., coupling constants), we can determine the structure and connectivity of atoms within a molecule.

Imagine it like tuning a radio: each nucleus is like a radio station broadcasting at a specific frequency (its resonance frequency). The NMR spectrometer is like the radio receiver, detecting and measuring the signals from each ‘station’ (nucleus) to determine its unique chemical environment.

Applications of NMR are incredibly broad, including determining the 3D structure of proteins, analyzing the composition of materials, and studying metabolic processes. It’s a crucial tool in chemistry, biochemistry, materials science, and medicine.

Radioactive tracers, also known as radioisotopes, are radioactive atoms incorporated into molecules to track their movement and distribution within a system. Their use is based on the principle that the radioactive decay of the tracer can be easily detected and quantified. They are invaluable in numerous research and industrial applications:

• Medical Research: Tracers are used to study metabolic pathways, drug distribution, and the effectiveness of therapies. For example, ¹⁸F-FDG (fluorodeoxyglucose) is a commonly used PET tracer to detect cancer cells based on their increased glucose metabolism.
• Environmental Science: Tracers are used to track the movement of pollutants in water systems, study soil erosion patterns, and monitor the spread of contaminants. For instance, tritium (³H) can be used to trace groundwater flow.
• Industrial Processes: Tracers help optimize industrial processes, such as tracking the flow of fluids in pipelines or investigating wear and tear in machinery. For example, radioactive isotopes can be added to lubricants to monitor their flow and distribution within a machine’s components.
• Agricultural Research: Tracers help understand nutrient uptake by plants, fertilizer distribution, and the efficiency of irrigation systems. For instance, ³²P can be used to study phosphorus uptake in plants.

The choice of radioactive tracer depends on several factors, including its half-life, the type of radiation emitted, its chemical properties, and the sensitivity of the detection methods available. Safety procedures are always paramount when using radioactive tracers, ensuring minimal exposure to personnel and the environment.

Radiation exposure can be categorized as either internal or external, depending on the location of the radioactive source:

• External Radiation Exposure: This occurs when a radioactive source is outside the body, emitting radiation that penetrates the body’s tissues. The severity of the exposure depends on factors like the distance from the source, the intensity of the radiation, and the duration of exposure. Examples include exposure to gamma rays from a nuclear power plant or exposure to X-rays during medical imaging.
• Internal Radiation Exposure: This occurs when a radioactive substance enters the body through inhalation, ingestion, or absorption through the skin. Once inside, the radioactive material emits radiation directly to surrounding tissues, causing localized damage. The severity depends on the type and amount of radioactive material, the route of entry, and the radioactive material’s biological half-life (how long it remains in the body). An example could be the ingestion of radioactive iodine or inhalation of radon gas.

Both internal and external exposure can lead to various health effects, ranging from minor skin irritation to severe damage to organs and DNA, depending on the dose and type of radiation. Protective measures, such as shielding and appropriate handling procedures, are crucial in minimizing radiation exposure in both scenarios.

Calculating the dose equivalent from different types of radiation requires considering the energy deposited by the radiation and the relative biological effectiveness (RBE) of each type of radiation. The dose equivalent (H) is calculated using the following formula:

H = D x WR

Where:

• H is the dose equivalent (measured in Sieverts, Sv)
• D is the absorbed dose (measured in Grays, Gy)
• WR is the radiation weighting factor, which accounts for the relative biological effectiveness of different types of radiation.

The radiation weighting factor (WR) is dimensionless and varies depending on the type of radiation:

• X-rays, gamma rays, and beta particles: WR = 1
• Alpha particles: WR = 20
• Neutrons: WR varies depending on energy

Example: If a person receives an absorbed dose of 0.1 Gy from gamma rays, the dose equivalent would be 0.1 Sv (0.1 Gy x 1). However, if the same absorbed dose (0.1 Gy) is received from alpha particles, the dose equivalent would be 2 Sv (0.1 Gy x 20). This illustrates that alpha particles are significantly more damaging than gamma rays at the same absorbed dose.

Calculating dose equivalent from mixed radiation fields requires summing the weighted doses from each type of radiation. This process is vital for radiation protection assessments and ensuring that exposures are within the acceptable limits set by regulatory bodies.

Several units are used to measure radioactivity and radiation dose:

• Becquerel (Bq): This is the SI unit of radioactivity, representing one nuclear decay per second. It quantifies the activity of a radioactive source.
• Curie (Ci): This is an older unit of radioactivity, where 1 Ci is equal to 3.7 x 10¹⁰ Bq. It is still used in some applications but the Becquerel is preferred.
• Gray (Gy): This is the SI unit of absorbed dose, representing the energy deposited by ionizing radiation per unit mass of tissue (1 Gy = 1 joule/kilogram). It measures the amount of radiation energy absorbed by the body.
• Sievert (Sv): This is the SI unit of dose equivalent, representing the biological effect of radiation on the body. It takes into account both the absorbed dose and the relative biological effectiveness of the radiation. It’s a crucial unit for assessing the potential health risks associated with radiation exposure.

It’s important to understand the differences between these units. The Becquerel and Curie measure the radioactivity of a source, while the Gray and Sievert measure the effect of that radiation on a living organism. The Sievert is particularly relevant for radiation protection, as it reflects the potential biological harm caused by radiation exposure.