The Process of Radioactive Waste Incineration

To protect the health of our environment and our communities, the proper storage and disposal of radioactive waste are critical. There are several methods for disposing of radioactive waste, including near-surface disposal, deep geological disposal, reprocessing, and mined repositories. In this blog, we’re focusing on incineration. Radioactive waste incineration was part of a major news story in this decade. After the Fukushima Daiichi Nuclear Power Plant suffered permanent damage from the Great East Japan Earthquake and tsunami in March of 2011, TEPCO (Tokyo Electric Power Co) built a three-story incineration facility to reduce the massive volume of waste created from the used radiation suits, gloves and boots of the plant’s 7,000 person staff. A years-long crisis ensued about how and where to store the over 170,000 tons of ash created from incinerated radioactive waste at Fukushima Daiichi, alleviated by the construction of a nationalized disposal site which began processing in 2017.

Incineration of Radioactive Waste: How it Works

Incineration can be an effective method for radioactive waste disposal but it does have some drawbacks related to managing and storing the ash produced. Incineration combusts or oxidizes wastes at high temperatures, forming ash, flue gas and heat. Waste is incinerated in a specially engineered kiln after the separation of noncombustible constituents. The high temperatures of incinerators, up to 1,100° C or 2000° F, are effective in reducing the volume of radioactive waste in heavier items like contaminated textiles, lumber, paper or plastic, sewage, and animal waste. Standard incinerator types include Controlled Air, Excess Air, Rotary Kiln, Fluidized Bed, Vertical Shaft, and Multiple Hearth. Less common incinerator designs are Microwave, Molten Glass, Molten Salt, Plasma Cyclonic, or Electric Infrared.

The gases and fumes generated by incineration must be treated and filtered prior to emission into the atmosphere. Federal government regulations set limits on radioactive releases from incinerators burning radioactive waste. The toxic by-products of incineration and their total toxicity remain highly uncertain but one of the better-understood toxins is dioxin, which can accumulate in fatty tissue and work its way up the food chain. Special filters can be effective at reducing toxins from incineration but some can still remain in the ash. Radionuclides concentrated in the ash may result in a “Class B” Waste even though the waste fed into the incinerator was a “Class A.” Rigorous ash control, processing, and storage are essential to minimize the risk of groundwater contamination.

When and Where Incineration is Used

While incinerators and “autoclaves” (basically industrial pressure cookers) are in wide use around the world, they are less so in the United States due to concerns about their toxic emissions. According to the World Health Organization, “…incineration equipment should be chosen on the basis of the available resources and the local situation, balancing the public health benefits of pathogen elimination against the technical requirements needed to avoid the health impacts of air or groundwater pollution from the by-products of waste combustion.”

Hospitals and other medical industries tend to produce low-level waste (LLW) that is often compacted and/or incinerated before disposal, particularly in the developing world. This type of waste can encompass paper, rags, tools, clothing, or filters, which contain small amounts of mostly short-lived radioactivity. While LLW is the majority of all radioactive waste – about 90% of the volume – it only accounts for 1% of the radioactivity of all radioactive waste.

Managing Radioactive Waste Disposal

Any university lab, manufacturing plant, medical facility or nuclear power plant should have a Radiation Safety Officer (RSO) and established safety plan. An RSO, whether at a nuclear reactor facility or a hospital, is responsible for the systems and processes that protect workers and the public, including strategies for radioactive waste disposal.