Radioactivity

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Radioactivity is a property exhibited by unstable nuclei resulting in the emission of particles and energy. An unstable nucleus decomposes spontaneously to form a stable nucleus. During radioactive decay, new elements are formed with the emission of electromagnetic radiation. The rate of decay is known as half-life during which half of the original amount of the unstable nucleus is reduced by half. Unstable nuclei undergo several cycles to form stable nuclei. The radioactive decay process may occur in three forms namely alpha, beta, and gamma radiations. The neutrino type is less common (L’Annunziata, 2016).

In 1895, Roentgen was busy working in his lab when he noticed that a strange fluorescence was emitting from a nearby work table. Roentgen observed that it emanated from a partly evacuated Hittof-Crooked tube, that was covered in opaque black paper. He says that he was working on cathode rays. According to the report he made later, he wrote that the fluorescence that had pierced through the opaque black paper must have been caused by rays. Roentgen could not figure out what caused the rays so he named them x-rays. Later discoveries disqualified x-rays from forms of radiation. However, Roentgen opened the door to further discoveries (Mann, Ayres & Garfinkel, 2016).

Antoine Henri Becquerel was the first person to discover radioactivity. He has a Nobel Prize in his honor. Roentgen motivated characters such as Henri who even used a similar experiment. Henri surrounded many photographic plates with black material and added fluorescent salts. What is ironic is that Becquerel only intended to advance knowledge on x-rays. It was a serendipitous discovery. The weather was bad on the day of his experiment, and, therefore, he was forced to delay the experiment (L’Annunziata, 2016). He positioned the enveloped plates in a dark desk. After a few days, he came back to his lab and unwrapped the papers, and was surprised to see that the fluorescent salts left distinct marks on the photographic material in the absence of energy.

In 1903, the Curie family was awarded a Nobel Prize in physics for their work in radioactivity. Marie Curie and Pierre Curie coined the term “radioactivity”. Curie used a device to measure the voltage of the air around uranium. She noticed that there was a change in the current. Her experiments revealed that radioactivity was dependent on the quantity of uranium and that the radioactivity was due to the atom itself. She discovered that radium and polonium were radioactive. Unfortunately, the curies died young, with the wife dying due to aplastic anemia likely due to exposure (L’Annunziata, 2016).

Ernest Rutherford is the father of nuclear physics. In 1903, he received a Nobel Prize in Chemistry for his contribution to the atomic structure of elements. It formed the basis of the modern understanding of the structure of the atom. The atom consists of a nucleus with protons and neutrons and is surrounded by negatively charged electrons (L’Annunziata, 2016). He also did numerous experiments on radioactive decay. He classified the types of radiation depending on their depth of penetration.

There are a variety of models that have attempted to elaborate on the structure of the atoms. John Dalton’s model stated that all matter consists of small particles. He coined the term “atoms” for the particles. According to his model, the matter is composed of minute atoms that are indivisible and indestructible. Also, the atoms have identical physicochemical properties. He stated that compounds are formed from a reaction between two or more different atoms. Most of his theory was correct. The only exceptions are that there are even smaller particles than the atom and the discovery of isotopes. In 1897, electrons were discovered. This led Thompson to propose the plum pudding model. In his model, the atoms contain electrons. Thompson was unaware of the presence of the nucleus. However, he knew that the atom was electrically neutral. In the plum pudding model, the electrons float in a soup of diffuse positive charge (Sproull & Phillips, 2015).

Rutherford disputed the Thompson plum pudding model. The plum pudding model stated that the electrons were floating together with positive mini-particles. However, Rutherford introduced the concept of the nucleus. In the planetary model, the nucleus contains positively charged particles which are surrounded by the lighter and negatively charged electron. He stated that the nucleus contains the bulk of the atomic mass. The majority of the concepts are still widely accepted in the world today. He, however, did not elaborate on why some atoms emitted light (Sproull & Phillips, 2015).

The Bohr model of the atom described the structure of the atom similarly to Rutherford. Furthermore, he explained why some atoms fluorescence. Bohr theorized that the electrons revolve around a positively charged nucleus. The electrons occupied distinct energy levels. The lowest level is called the ground state and is the most stable. Electrons absorb energy and move from lower energy levels to higher energy levels (Sproull & Phillips, 2015). The higher energy levels are called the excited states. Energy is absorbed or emitted in photons between the orbits.

The quantum mechanical model of the atom is the current description of the structure of the atom. The model makes numerous assumptions. All particles are perceived as matter waves with a distinct wavelength. The other assumption is based on the principle of uncertainty states, which says that one cannot know the energy and location of an electron. There exists more than one energy level in an atom (Sproull & Phillips, 2015). The electrons have two intrinsic spin properties. Not two electrons in a given orbital can have the same spin. Four quantum numbers are used to describe the traits of electrons and their orbitals. The numbers are principle quantum number, angular momentum, magnetic quantum, and spin quantum numbers.

Natural radioactive decay series

In alpha decay, an energetic Helium atom is emitted. The resulting daughter nuclide has an atomic number which is two less than the parent. The atomic mass number is four less than the original molecule. An alpha particle can be stopped with a few centimeters of air, hence possess the least penetrating ability. Since it is the heaviest it is the most ionizing. The particles have a net charge of zero. The velocity of alpha particles is 4% of the speed of light. The beta particles are high energy, high-speed electrons emitted during the radioactive process. Beta particles have a higher penetrating ability than alpha particles. The particles are also lighter, hence, they travel at a higher speed than alpha. The speed is approximately 0.9 x speed of light. They have lower ionization properties than the former due to the small mass. Gamma radiation is a form of energy emitted from the nucleus. It has the most penetrating power (Adloff, 2018). Also, it travels at the speed of light. Besides, gamma radiation has the least ionizing property since it tends to lose all its energy at once. It can be stopped by a thick concrete or lead. However, like all other forms of radioactivity, it has severe damage to living organisms.

Radiation detectors

A radiation detector is a device used to identify high energy particles. In the early stages, photographic plates were utilized to identify the paths left by nuclear interactions. Modern devices use calorimeters to quantify the energy of the detected radiation. The scintillator exhibits scintillation in the presence of ionizing radiation. The gaseous ionizing detectors are also used to detect ionizing radiation. The Geiger Mueller counter is the most commonly used detector. The GMC has a gas-filled tube at high voltage that responds to incident ionizing radiation. It cannot distinguish between the various types of radiation (Mann, Ayres & Garfinkel, 2016).

Acute radiation syndrome

Acute radiation syndrome is an immediate sickness that develops from extreme radiation exposure over a small period. The large doses result in cellular damage within a short period. There are four stages of the ARS. The first one is the prodromal stage which is characterized by anorexia, nausea, vomiting, and diarrhea. In the latent stage, the patient may have few or no symptoms at all. The manifest illness level may have features of the three specific syndromes namely, hematopoietic, gastrointestinal, or neurovascular. The recovery or death stage is the fourth stage. It may take one up to two years to fully recover. Those who do not recover die within a few weeks or months. The three ARS syndromes occur depending on the amount of radiation exposure. The neurovascular syndrome requires the highest amount of dose, while the hematopoietic syndrome requires the least dose. Long term exposure to radiation leads to cancer and death (Desouky, Ding & Zhou, 2015).

Radiation-induced damage to DNA

When radiation interacts with matter several things can happen. The effect is dependent on the dose and the length of exposure to electromagnetic radiation. The radiation could pass through the cell without affecting it. In some cases, the radiation may harm the DNA, and the cell may repair itself. In some situations, the radiation may lead to apoptosis. Ionizing radiation can cause direct damage to the DNA molecules leading to cancer. Radiation may cause a change in the chemical structure of the bases. It may also break the sugar-phosphate backbone. It may also break the hydrogen bonds connecting the base pairs (Desouky, Ding & Zhou, 2015). The result is either DNA damage or DNA mutation. Ionizing radiations have indirect damage to cells and DNA. For example, radiation can form radicals such as ROS that may lead to DNA damage. Radiation-induced mutations are alterations in the genome. Hence, it can alter either the chromosome or the genes. Mutations that occur in gametic cells are passed on to future generations. Radiation-induced carcinogenesis is widely believed to occur as a result of exposure to ionizing radiation. Living cells are damaged, and the normal physiological cell cycle regulators are impended. As a result, the surviving cells are outside the regulating mechanisms, which lead to cancerous growth.

Radioisotopes are widely used in the biological fields. Radionuclides are used to tag biological particles before commencing biochemical assays. The assays determine the constituent of the plasma and body fluids. The technique is known as radioimmunoassay. An example is the iodine bioassay that emits gamma radiation using iodine-125 and iodine-131 (Yeng, Cheng & Ng, 2014). Radionuclides can be used to determine the GFR during urinalysis. Radionuclides may be used to conduct trace studies in an organism. Radioactive C-14 is utilized in carbon dating. The radionuclide K-40 decays to form argon, hence, is applied to investigate the age of rocks. Positron Emission Tomography (PET) makes use of radionuclide emitting positron particles. The positrons react with nearby negatively charged particles to emit gamma rays that are sensed by the PET. Radionuclide therapy utilizes radioisotopes that emit radiations upon decay. The released radiations are utilized in radiotherapy, especially in cancer. Surgical instruments are sterilized using gamma-emitting radionuclides.

Radionuclides are employed in many sectors, especially in the medical field. The exposure to ionizing radiation lead to serious medical problems hence, the need to protect the workers from occupational harm. Employers seek to minimize stochastic risks. The basic principle is to ensure that the dose limit is as little as rationally attainable. Essentially, the dose should be below the limit and effective to treat the patient. The control of occupational exposure should be systematic (Yeng, Cheng & Ng, 2014). It starts from the design of the facility, the workplace, monitoring contamination, the use of personal protective tools, and following the local rules and regulations for the safe handling of radiopharmaceuticals. The organization should focus on training its personnel. Public access to the nuclear medicine department should be restricted. Apart from this, the patient’s family needs to be educated on how to handle their patient who is radiotherapy.

Short and long term effects of the atomic bombs

It is estimated that between 150000-200000 died in Hiroshima and Nagasaki as a result of the two bombs that were detonated by the American government in World War 2. Some of these people gradually. The deaths were referred to as acute deaths. The survivors of the atomic bombs have been under the radar since 1950. They are assessed to determine their health. The studies focus on utero exposure, life span, pathology, and adult health. The offspring of the survivors are studied for mortality, biochemical genetics, and cytogenetics. Cancers are prevalent in this population. The Chernobyl accident was a product of severely flawed reactor design. It was an RBMK reactor design. The Soviet Union stubbornly used this design despite widespread rejection from around the world. The main concern was the inherent instability, particularly on startup and shutdown. Thirty-one people died from the accident. The accident led to approximately 20,000 cases of thyroid cancer, especially among the youth. The vegetation was intoxicated with the radioactive material, and the animals died. Those that thrived spread the radionuclides to humans (Beresford et al., 2016).

Nuclear weapons pose significant threats to the world. One would argue that no nuclear weapons have been used since world war 2. However, more powerful and destructive weapons are tested weekly. The weapons are tested underground (Futter, 2015). The only thing that has been suspended is the use of these weapons on military and civilian people. The world talks of nuclear disarmament but the actions reveal otherwise. For example, during the Cuban crisis of 1962, the US used its nuclear power to threaten the Cuban government to submission. Currently, the issue of disarmament is only addressed by a political and technical background. Critics argue that the world should shift focus to moral and ethical issues regarding the use of these weapons. From a moral ground, a state should not use weapons that they would not like to be used against them due to the long term and short effects on people. It is immoral because of what the effects continue to do to people. And also, it is immoral because of what the nuclear industry is prepared to do in the name of national security. Human beings should promote the continuation of human survival instead of annihilating it (Davidson, 2019). The move ought to be towards quality engagement. To do that, a new culture and language of peace should enshrine all the talks about the use of nuclear weapons.

References

Adloff, J. P. (2018). Fundamentals of radiochemistry. CRC Press.

Beresford, N. A., Fesenko, S., Konoplev, A., Skuterud, L., Smith, J. T., & Voigt, G. (2016). Thirty years after the Chernobyl accident: What lessons have we learned?. Journal of environmental radioactivity, 157, 77-89.

Davidson, D. L. (2019). Nuclear weapons and the American churches: Ethical positions on modern warfare. Routledge.

Desouky, O., Ding, N., & Zhou, G. (2015). Targeted and non-targeted effects of ionizing radiation. Journal of Radiation Research and Applied Sciences, 8(2), 247-254.

Futter, A. (2015). The politics of nuclear weapons. Sage.

L’Annunziata, M. F. (2016). Radioactivity: introduction and history, from the quantum to quarks. Elsevier.

Mann, W. B., Ayres, R. L., & Garfinkel, S. B. (2016). Radioactivity and its Measurement. Elsevier.

Sproull, R. L., & Phillips, W. A. (2015). Modern physics: the quantum physics of atoms, solids, and nuclei. Courier Dover Publications.

Walker, J. S. (2016). Prompt and utter destruction: Truman and the use of atomic bombs against Japan. UNC Press Books.

Yeong, C. H., Cheng, M. H., & Ng, K. H. (2014). Therapeutic radionuclides in nuclear medicine: current and future prospects. Journal of Zhejiang University SCIENCE B, 15(10), 845-863.