Types of nuclear waste generated from nuclear power station
The nuclear wastes produced from nuclear power station are classified into three categories (i.e. gas, liquid and solid wastes). The disposal of nuclear wastes is based on the principle of recycling and minimize the release quantities as far as possible. The management of the nuclear wastes must comply with the requirements of the national safety regulations. The release of the nuclear waste is strictly monitored and controlled by the national authority and the actual release is far below the prescribed permissible quantities.
Each nuclear power station has its own waste processing facilities to properly treat the gas and liquid wastes generated during daily operation of the plant. The waste treatment process includes filtering, clean-up, storage, decay and dilution depending on the characteristics of the wastes and its radioactivity. When the radioactivity of the waste has diminished to a very low level, it would be released to the environment on condition that it would not exceed the permissible limit. The gaseous waste is released to the environment after treatment via the stack. The liquid waste is mixed and diluted with the effluent from the plant after treatment before discharging to the sea.
Solid nuclear wastes produced by the nuclear power station will not be released to the environment. There are three types of solid nuclear wastes classified in terms of its radioactivity (i.e. low, intermediate and high-level wastes).
Low-level waste (LLW)
Low-level waste (LLW) consists of daily refuse such as paper, gloves, plastic containers, disposable overalls and overshoes with low radioactive contamination. LLW is compressed into steel drums, sealed and stored temporarily at the nuclear power station and eventually be transported to the repository for disposal.
Intermediate-level waste (ILW)
Intermediate-level waste (ILW) consists of radioactive resin and chemical sludge, spent filter cartridges etc. collected from waste treatment process and maintenance work. ILW is solidified by mixing it with sand/cement and then poured into concrete drums. The ILW would be transported to the repository for burial eventually after temporary storage at the nuclear power station.