ARTICLE

 

RADIOACTIVE WASTE: TREATMENT AND MANAGEMENT

Aswathy Aji P
St. Joseph College of Teacher Education for Women, Ernakulam

 

ABSTRACT

Energy is fundamental for meeting human needs, driving economic growth, and enhancing the standard of living. Nations often equate their well-being with the escalating demand for energy, considering it a crucial element in sustaining and advancing their prosperity. Nuclear energy is an efficient energy source. Nuclear energy, while offering numerous benefits, presents inherent drawbacks and risks, notably in the realm of radioactive waste disposal. Nuclear energy has been well utilized in many ways, especially in the field of nuclear power generation. However, as the number of nuclear power plants continues to increase, it intensifies the challenge of effectively managing nuclear waste (radioactive waste). The world has over half a century’s knowledge and experience on how to deal with nuclear waste ad what to do with the leftover radioactive waste. Nuclear waste disposal is a complex process. If not handle it properly, it can harm people and the environment. For nuclear waste treatment, people initially stored it temporarily or directly dumped it. However, as people's awareness of nuclear waste increases and the huge potential threat of nuclear waste are known, it is necessary to analyze the current characteristics of nuclear waste in order to find a better nuclear waste treatment and management method. The primary goal of waste management is to safeguard both current and future generations.

Keywords: Radioactive waste, nuclear energy, radiation, hazardous, disposal, nuclear waste management

 

INTRODUCTION

Modern life is filled with technology and the technology often creates radioactive. Radioactive waste is an unavoidable by-product of the use of radioactive material and nuclear technology. Most radioactive waste comes from nuclear power plant. it is also generated in hospitals from the use of radioactive material to diagnose and treat the sick and sterilize medical products, in universities in conducting important research in biology, chemistry and engineering, and and even in agriculture for better crops. Radioactive waste can be hazardous to health and the environment. To tackle this, we need to handle the waste carefully to make sure it doesn't expose us to too much radiation. The main goal here is to protect human health, the environment, and the well-being of future generations. So, managing radioactive waste is crucial – whether it's from power plants, hospitals, universities, or agriculture – to keep everyone safe and make sure we follow the rules and standards set to control radiation exposure

RADIOACTIVE WASTE

Radioactive waste is a type of dangerous waste containing radioactive substances. It consists of materials that are naturally radioactive or has been contaminated by radioactivity, and is no longer useful. Various industries producing this waste include nuclear power, nuclear medicine, nuclear research, coal and rare-earth mining, manufacturing, construction, and nuclear weapons reprocessing. The key is that once something becomes radioactive waste, it’s deemed useless and has to be handled carefully due to its potential harm.

TYPES OF RADIOACTIVE WASTE

According to the form of radioactive waste, it can be divided into three

1.      Radioactive gaseous waste

2.      Radioactive liquid waste

3.      Radioactive solid waste

According to The Environmental Protection Agency (EPA), there are five types of radioactive waste

1.      Low-level waste (LLW) -contaminated industrial waste.

2.      Transuranic waste (TRUW) from the production of nuclear weapons.

3.      Uranium mill tailings from the mining and milling of uranium ore.

4.      Spent nuclear fuel (SNF) from reactors and High-level waste (HLW) Spent reactor fuel and other highly radioactive wastes generated at reprocessing plants.

5.      Naturally occurring radioactive materials (NORM)

CLASSIFICATION OF RADIOACTIVE WASTE

Classification of radioactive waste differs from country to country. According to the INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA), Radioactive Waste Safety Standards (RADWASS), has classified the radioactive waste into six categories based on the amount of radioactivity. it contains

1.      Exempt waste (EW).

2.      Very short lived waste (VSLW).

3.      Very low level waste (VLLW)

4.      Low level waste (LLW).

5.      Intermediate level waste (ILW).

6.      High level waste (HLW)

1.      Exempt waste (EW)

Exempt waste has a low level of radioactive materials which is not considered harmful to people or the environment. This waste mainly includes materials like concrete, plaster, bricks, and metals from nuclear power sites. These materials are safe and don’t need special disposal facilities because they’re harmless and they pose no threat from radiation.

2.      Very short lived waste (VSLW)

Very Short-Lived Waste (VSLW) contains radio nuclides of very short half-life, making it harmful for a brief period as it quickly undergoes radioactive decay. Such waste is store until its radioactivity drops to the level of exempt waste, becoming harmless to the environment. Examples of VSLW include radioactive waste from industries and medical applications, where the materials have short half-lives and lose their harmful effects relatively fast.

3.      Very low level waste (VLLW)

Very Low-Level Waste (VLLW) is a waste from nuclear facilities and their shutdown, where the radioactivity is a bit higher than exempt waste but still quite low. Waste with such a limited hazard, which above or close to the levels for exempt waste, is termed very low level waste. Safety from radiations of such waste is achieved by careful disposal in engineered surface landfill facilities.These are designed to make sure the waste is contained and doesn’t pose a risk to people or the environment.

4.      Low level waste (LLW)

Low level waste (LLW) comes from hospitals, industries and nuclear fuel cycle. It includes things like paper, rags, tools, clothing, filters, and medical waste.This waste has small amounts of short-lived radioactive. So no heavy shielding is needed during handling or transport and is suitable for shallow land burial. The range of radioactivity in LLW goes from a bit above Very Low-Level Waste (VLLW) to levels where some shielding is needed for a few hundred years. Low level wastes are disposed at varying depths from the surface down to 30 m.

5.      Intermediate level waste (ILW)

Intermediate-Level Waste (ILW) is a long-lived radioactive material and needs more isolation and shielding. Reactor metal cladding resins and chemical sludge falls into this category. To dispose of ILW safely, it's buried at depths ranging from a few tens to a few hundred meters. Sometimes, it's solidified in materials like concrete or bitumen for safe disposal. It contains 4% of the radioactivity in the world's radioactive waste. So, it requires extra care due to its longer-lasting and more significant radioactivity.

6.      High level waste (HLW) 

High-Level Waste (HLW) is a serious concern, holding 95% of the world's radioactive activity. It comes from the reprocessing spent nuclear fuel, containing uranium fuel and transuranic elements from the reactor core. This waste is intensely radioactive, with high temperatures requiring both shielding and cooling. Most HLW is found in spent fuel and separated waste from reprocessing. It contains high concentrations of both short and long-lived radioactive materials. Though recycling spent nuclear fuel is an option, it's not a complete solution as the separated waste still contains HLW. The safest method for disposal is deep burial in geologically stable locations, as this helps prevent any harmful effects on the environment. It’s a crucial step in managing the substantial radioactivity contained in high-level waste.

HAZARDS OF WASTE

In a nuclear power plant, a specific type of radiation known as ionizing radiation, which is a form of energy that’s capable of removing electrons from atoms, is emitted both naturally from uranium and as part of the nuclear fission process. These radiations have somatic effects and genetic effects. The physical effects mainly include:

1.      Acute injury: damage caused by large doses of the human body in a short period of time

2.      Chronic injury: caused by low-dose irradiation of long-term, super-allowable dose limits.

3.      Long-term effects: refers to the effects that occur after 6 months of exposure, mainly including leukemia, aplastic anemia, malignant tumors, cataracts, and effects on early fetuses.

The presence of this radiation negatively impact both workers and public health. Workers in nuclear plants and emergency teams face heightened risk of high radiation exposure, resulting in Acute Radiation Syndrome (ARS), also known as radiation sickness or radiation poisoning. ARS symptoms include skin burns, vomiting, diarrhoea, and potentially coma. The cause of death in most cases of ARS is damage to the bone marrow, which leads to infection and internal bleeding. Additionally, intense ionizing radiation exposure harms DNA, causing cancers and genetic mutations that can be transmitted to future generations. Even lower exposures pose an elevated risk of cancers like leukemia and thyroid cancer.

At the same time, nuclear waste can also pollute the environment. Environmental impacts include soil, air and water contamination affecting ecosystems and wildlife. It had a notable impact on diverse animal species, including fish, birds, and mammals. The disruptions caused by nuclear radiation extend to the health systems of these various animal species. It had profound effects on the plant life in their respective regions, causing disruptions in their growth and leading to the death of different types of plants. Radiation spread into the air and atmosphere and caused its contamination.

STORAGE AND DISPOSAL OF RADIOACTIVE WASTE

1.      Deep geological repository.

2.      Spent fuel pool.

3.      Dry cask storage.

4.      Near surface disposal

 1.      Deep geological repository

A deep geological repository is like a secure underground storage space designed to keep highly radioactive waste (HLW) safe from harming humans. It’s built beneath the ground to shield people from dangerous radiation. The repository has layers of natural and man-made barriers that act as shields, ensuring the safety of the stored radioactive waste. This way, human activities above ground don’t interfere with the storage, creating a protective environment.

2.       Spent fuel pool (SFP)

Spent fuel pools serve as a storage solution for the radioactive fuel discharged from the nuclear fuel cycle. Filled with thermally controlled water, these pools use water as a natural barrier against radiation. When the spent fuel is taken out of the reactor for replacement with new fuel, it's necessary to store it in these pools for a specific duration.The underwater storage is crucial because the decay of fission products in the spent fuel generates heat. This underwater storage helps manage the heat and limits radiation levels around the spent fuel pool. Over time, as the heat diminishes, the spent fuel is moved to ground level. Specially designed casks are employed for this purpose, providing effective radiation shielding to ensure safety during storage

3.       Dry Cask Storage

 Once highly radioactive waste (HLW) has cooled in the spent fuel pool, it’s moved to dry cask storage at ground level. These storage containers, called casks, are made of steel and are sealed either by welding or bolting. Inside, the fuel rods are surrounded by inert gas. The steel cylinder is designed to prevent any leaks of the spent fuel. Each cask is then surrounded by extra layers of steel, concrete, or other materials to shield workers and people nearby from radiation. Some of these casks are versatile and can be used for both transportation and storage purposes.

4.      Near surface disposal

Near surface disposal involves the disposal of low-level (LL) and short-lived intermediate-level (IL) radioactive waste either at ground level or in underground caverns. These disposal sites utilize a combination of natural and engineered barriers. Excavation is carried out for sites at or below the surface, allowing for the placement of waste with several meters of soil covering. The waste, typically solid and including very low-level (VLLW), low-level (LLW), very short-lived (VSLW), and short-lived intermediate-level (ILW) materials

MANAGEMENT OF RADIOACTIVE WASTE

The practice of nuclear science and energy production results in a growing volume of radioactive waste each year. This waste, containing radioactive elements harmful to living organisms and the environment, requires unique management to protect human health and minimize environmental impact. Radioactive waste varies widely in terms of radioactivity, chemical composition, and physical characteristics. The proper disposal of these wastes varies based on their specific properties. The choice of disposal and safety measures depends on how long the waste remains hazardous. Ensuring the safe management of radioactive waste is crucial for safeguarding our health and the environment

Nuclear waste management involves both administrative and technical tasks throughout the entire lifecycle of nuclear waste. This includes activities such as waste generation, pre-treatment, treatment, conditioning, storage, transportation, disposal, and decommissioning. It is the whole process management from waste generation to disposal. To handle nuclear waste responsibly, specific principles and systems are followed to minimize waste generation and ensure safe disposal. These principles guide the entire process, from production to disposal. Different countries have their own management principles tailored to their specific needs and regulations, ensuring a systematic and safe approach to nuclear waste management on a global scale

Nuclear waste management must indeed protect human health to an acceptable level. Nuclear waste management must indeed protect the environment to an acceptable level.  Nuclear waste management must take into account the impact on human health and the environment when transferred across national borders. Nuclear waste management must ensure that the health hazards it may cause to future generations are not expected to be greater than today's acceptable levels. Waste management must ensure that the current treatment can be handled resolutely, with as little unnecessary burden as possible for future generations. Nuclear waste management must be supported by a corresponding national legal framework. The generation of nuclear waste must be reasonably minimized.

Based on the generation country, radioactive wastes are managed according to the country’s safety regulation rules. Each country has developed and implemented standardized procedures for different kinds of radioactive waste they produce. Since radioactive materials become less radioactive over a given time, the best way to manage radioactive waste is to store them until they lose their radioactivity. Different radioactive materials have different half-lives, implying different storage times. Very short-lived radioactive wastes are disposed of by storing them in buildings until they are non-radioactive. HLW from nuclear fuel cycle require storage of thousand years, whereas ILW and LLW need hundred years or less for becoming non-radioactive. Considering the distinct characteristics of solids, liquids, and gases, each type of waste undergoes specific processing methods. Throughout this process, minimizing the risk of public exposure, ensuring the safe management of radioactive waste.

CONCLUSION

In recent decades, nuclear energy has played a significant role in electricity generation, and its demand is expected to rise in the future to meet growing energy needs. However, the byproduct of nuclear processes, radioactive waste, poses a challenge. This waste, left after using radioactive materials in reactors or producing nuclear weapons, emits radiation, leading to potential harm. To address concerns regarding public safety and environmental impact, the storage and management of radioactive waste are critical issues. With the necessity of public safety and the environment, radioactive waste disposed of in a safe manner.

Radioactive Waste Management encompasses a sequence of operations starting with the generation of radioactive waste, including its storage and disposal.  The nuclear industry is concern with the wastes it generates, employing advanced treatment and management techniques to effectively isolate it from the biosphere. Managing radioactive waste involves collecting the waste, implementing necessary treatments followed by a long-term management strategy. This strategy may include storage, disposal or transformation of the waste into a non-toxic form.  Throughout this process, the priority is to safeguard the waste and ensure the utmost safety for both human health and the environment, for now and in the future without imposing undue burdens on future generations.

Nuclear energy is one of the cleanest, most efficient, most available forms of power in the world. However, the challenge arises from the fact that waste produced by nuclear reactors remains radioactive for tens to hundreds of thousands of years. Storing nuclear waste in one place for the long term isn’t feasible because it requires a lot of space, and as we use more nuclear energy, the issue grows. To solve this, we need careful planning, clear direction, and enough funding for a sustainable, permanent solutionTo ensure long-term public safety, the solution lies in disposing of this waste in appropriate containers within engineered and naturally secured multi-barrier facilities, left undisturbed and isolated indefinitely. Though a majority of radioactive waste can be disposed of permanently in acceptable routes that are established around the world, some radioactive waste needs long term disposal plan. Various disposal methods, such as ocean disposal, outer space disposal, and underground burial, have been used to dispose of high-level radioactive wastes. Each method undergoes careful consideration to strike a balance between harnessing nuclear energy’s benefits and responsibly managing the long-lasting impact of its by-products.

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