How many applications does nuclear technology have?

The diverse applications of nuclear energy are fundamental to everyday life. Moreover, in the future they will be even more important thanks to the investigations that increase the possibilities of their application and justify their use.

Industry

The use of isotopes and radiations in modern industry is of great importance for the development and improvement of processes, for measuring, automation and quality control. Currently, almost all branches of technology use radioisotopes and radiations of diverse forms:

• Tracers: Radioactive substances that are introduced into a derterminate industrial process, to detect their trajectory thanks to their radioactive emission. This allows the investigation of different variables of the process (flows, filtrations, leaks, etcetera) in order to obtain information valuable towards extending the life of industrial equipment.
• X-rays of the pieces’ internal structure: This is a quality control application. It’s done with gamma rays or neutrons, for which reason they are known as gammagraphies or neutrographies. It is a non-destructive method that makes it possible to check the quality of weldings, metallic or ceramic pieces, etcetera, without damaging or altering the material’s composition.
• Improving the quality of determinate products: This consists on irradiating with intense sources in order to improve the quality of determinate products. Example: Polymerization by radiation, used for the manufacturing of plastic and for sterilizing “one use only” products.
• Zinc (Zn-64) injection into the nuclear reactor cooling liquid: This reduces the radioactive dose rate and in many cases mitigates the initiation of cracks by caused by corrosion from tension.

Hydrology

Out of all the Earth’s water resources, only 2.5% are sweet water, the rest are salty. The key for the sustainable management of water resources consist of possessing the necessary knowledge to make the right decisions.

Isotopic hydrology is a nuclear technique that is used both for stable and radioactive isotopes, to trace the movements of water in the hydrologic cycle. Isotopes can be used to investigate underground water sources and to determinate their origin, their recharge method, whether there is any risk of intrusion or contamination by salty water and whether it is possible to use it in a sustainable form.

Both hydrogen and oxygen, which are the constitutive elements of water, contain mostly light isotopes. In the evaporation and condensation stages, the concentration of oxygen and hydrogen isotopes in a molecule undergoes small changes. The oceans are responsible for sending the greatest amount of water steam to the atmosphere, and when this is produced the heaviest isotopes are condensed first, then fall down as rain before the lighter ones. Thus, the furthest rain is from the coast, the less heavy isotopes it carries. Oxygen and hydrogen isotopes, contaminating isotopes such as metallic traces or chemical compounds, are as singular as a finger print, and this gives off some clues as to their origins.

Mining

Through the use of nuclear sounding lines the physical and chemical state of the ground can be determined, and this makes it possible to learn if a stratus meets favorable conditions to house minerals or fuels. Some of its applications are diagraphy of monitoring wells and isotopic dating.

Agriculture and food

• Improve the quality of the food: Such as, for instance, the direct radiation of food in order to post-harvest losses, and lengthen their conservation period, so that when food is exposed to a predeterminate controlled gamma radiation dose using radiation energy to eliminate insects and pathogenic germs and delay ripening in fruit. This technique, accepted and recommended by FAO, WHO and IAEA, consumes less energy than conventional methods and can radically replace or reduce the use of additives and fumigants in foods. Irradiated food is also known as ionized or ionized radiation treated food, and must not be mistaken for radioactive food, since they emit no radioactivity.

• Plague control: The technique is the sterilization of insects that are considered plagues. These insects are raised in special sites and irradiated before incubation. The sterile insects are then disseminated to infected areas. Since they do not produce descendants, the plague’s population goes down and is eventually eradicated.
• Neutronic sounding waves: They are used to measure humidity and are perfect to make the most of limited hydric resources. In some cases it has been possible to save up to 40% of the water.

Medicine

Nuclear medicine techniques might be, along with nuclear energy production, the best known and widely accepted. In the industrialized Western world, diagnosis and treatment techniques have become as commonplace, reliable and precise that approximately one in every three patient undergoes some sort of therapeutic radiologic or diagnosis proceeding.

• Radiopharmaceuticals: Mostly organic, radioactive chemical compounds that are administered to the patient to investigate a biological process or the functioning of an organ inside the human body. Currently over 300 radiopharmaceuticals are used for diagnosis. Some must be produced within the hospital since their medical life is very short, but most are produced at nuclear centers or specific nuclear laboratories.
• Gammagraphy: Once the radiopharmaceutical has been administered to the patient, and thanks to its special affinity, it fixes itself to the organ that is to be studied and then emits gamma radiation, which is then detected by a gammachamber via a detector placed over the organ under exploration. These signals are transformed by a computer attached to the equipment, which permits the spatial representation of the organ. Diagnosis by nuclear images provides unique information on the performance of diverse organs, such as the heart, thyroid gland, kidneys, liver and the brain, and it also makes it possible to diagnose a wide range of tumors.
• Radiotherapy: This is a medical specialty that uses the application of ionizing radiations with curative means for the destruction of malignant tissue and tumors. This therapy might be used on its own or associated to other therapeutic means such as surgery or chemotherapy. Example: Cobalt therapy, which uses sources of Cobalt-60.
• Diagnosis through radioisotopes: Radioisotopes such as Carbon-11, Zirconium-89 and Fluoride-18 are used for PET scans, Cripton-81m is used to obtain images from lung performance, Strontium-89 for bone cancer therapy, Iodine-131 for thyroid cancer, etcetera.
• Sterilization of medical equipment: Through radiation. It’s a highly efficient and low-cost process.
• Knowledge of biological processes through tracers: The information provided by the marked molecules in the different stages of the cellular cycle and the help given by analytic separation techniques have made it possible to determine miniscule concentrations of enzymes, hormones, drugs, poisons, etcetera through the technique of radioimmune analysis (RIA), which makes use of the specificity of antigen-antibody reactions.
• Study of the characteristics of tumor cells, their location and extension: It makes it possible to plan the radiation type, calculate the total dose, the administration method and its possible fractioning with intervals of rest in order to facilitate the tumor’s progressive reduction, thus favoring the elimination of dead cells and permitting a better repair of surrounding tissues.

Art

Some examples of the application of nuclear technology to art are:

• Heritage conservation: The problem presented by a deteriorating piece of art is twofold: on one hand, the progressive loss of fixation it endures by being exposed to the environment, and on the other hand the contamination with xylophagous insects (they feed on wood), fungi, etcetera. By permeating it with a monomer (small molecule) and then performing gamma radiation on it, it is possible to produce the consolidation of the piece by polymerization (chemical grouping of compounds), while at the same time eliminating the contaminating insects by sterilization.
• Age determination: To date works of art, just as it is done to determine age on geological and archeological formations, the Carbon-14 technique is used. This technique consists in determining the quantity of these isotopes contained inside an organic body. Due to the presence of Carbon-14 the existing radioactivity goes down by half every 5,730 years, for which reason, by precisely measuring its activity (and quantity) the age of the sample might be inferred.
• Authenticity of artworks: Through non-destructive analyses, it is possible to obtain information on the “digital fingerprints” of artworks; that is to say, micro-constituent elements of the prime matter that vary according to the author and the time.

The Environment

It is used to detect and analyze various contaminating agents. One of the best known techniques is called Neutronic Activation Analysis, and consists of irradiating a sample in such a way that afterwards it is possible to obtain the gamma specters emitted by it. Computer processing of this information identifies the elements in the sample and their concentration.

Nuclear techniques have been successfully applied to several contamination problems such as those caused by sulphur dioxide, gaseous discharges at ground level petroleum spillages, agricultural waste, water contamination and in the contamination generated by cities.

Space exploration

One of the main applications of nuclear technology is space navigation, using nuclear batteries. This means the isotopic electric generators are instruments that contain a hermetically encapsulated radionucleid, whose radiation are absorbed into the capsule’s walls. This is the equivalent to a heat source, since the capsule transforms energy from radiations. This source is fixed to an electric circuit to generate an electric current that feeds the instruments. The source will be long-lasting if the radioisotope’s semi-disintegration period is long.

Unmanned flights to planets outside the Earth’s solar system have been carried out in missions provided with robotic feeding on the electricity produced by the radio isotope Plutonium-238, with a semi-disintegration period of 87.74 years and not fissionable like other isotopes of Plutonium, for which reason it can only be obtained from the uranium irradiated fuel.

The European Space Agency is considering the substitution of Plutonium-238 with another electricity-generating isotope, to cater to the needs of electric and electronic equipment used for measuring and transmission of data to Earth. One of the isotopes being considered is Americium-241, commonly used in fire detectors, and also an alpha emitter whose disintegration heat is similar to that of Plutonium-238, but which has a disintegration period of 432.2 years. This makes it possible to use it for longer missions, although a larger  quantity will be required in order to achieve the same amount of energy.

Cosmology

Modern cosmology embraces a wide span of ages, from the beginning of rock formation to current times. Current measuring techniques for the ages of stars are based on the stars’ masses, chemical compositions, temperatures and their comparison of how they vary with time according to the particular type of star.

In the case of rocks, the most followed dating method is the one based on comparing uranium-lead. Zircons are silicates found in igneous rocks, which sometimes incorporate small quantities of uranium in their crystalline structures. This uranium contains Uranium-238 (whose period is 45 billion years) and Uranium-235 (with a period of 740 million years). Both decline until they reach a stable lead form.

For younger rocks and objects with a human origin, other radioisotopes are used. One of them is based on the disintegration from potassium to argon. The most important part of human history, spanning about 60,000 years, is written on the carbon isotopes, the stable carbon-12 and carbon-14 (with a 5,730 year period).