The insulation and sheath materials of cables used in nuclear power plants must use low-smoke, non-toxic, non-corrosive halogen-free flame-retardant materials, such as thermoplastic flame-retardant halogen-free or cross-linked flame-retardant halogen-free materials to meet special nuclear safety requirements.
In the event of a fire, the halogen-free cable emits a very low amount of smoke and is non-toxic. Its flame-retardant components can effectively play a flame-retardant effect and will not make the cable a channel for flame spread.
High-quality fine aluminum hydroxide is usually used as a flame retardant in the cables.
The materials for nuclear power plant cables must have environmental resistance, that is, heat resistance, radiation resistance, and LOCA resistance.
1)Heat resistance: as nuclear power plant cables often work in high-temperature environments, therefore, they need to have long-term heat-resistant performance, select polymers that meet the required heat resistance, and allow the cable to have a service life of more than 40 years.
2)Radiation resistance: When the cables used in nuclear power plants are exposed to a large amount of radiation, the insulation and sheath materials will become brittle and the mechanical properties will deteriorate. Therefore, the insulation and sheath materials for nuclear power station cables must have excellent radiation resistance.
3)LOCA resistance: In nuclear power plants, the loss of cooling accident (LOCA) and the high energy linebreak (HELB) are usually collectively referred to as LOCA. When LOCA/HELB occurs, the cable will be subject to the impact of high temperature and high-pressure steam and corrosive chemicals and will be exposed to a higher dose of radiation. Therefore, nuclear power plant cables should have LOCA resistance.