Introduction to Nuclear Power Plant Cables

Nuclear power plant cables refer to the raw materials used for insulation and sheath of nuclear power plant cables, including various varieties such as plastic and rubber. The type of cable is determined by the type of cable.

type

There are two classification methods for nuclear power plant cables: one is based on function, including measurement cables, communication cables, instrument cables, fire-resistant cables (silicon insulated cables), etc; Another method is to classify cables used in nuclear power plants according to their safety level. The safety level of cables used in nuclear power plants belongs to IE level and should have a service life of more than 40 years. IE level nuclear power plant cables are further divided into three safety levels: K1, K2, and K3,3. The development process of nuclear power plant cable products is essentially the replacement of materials, the selection of cable types and raw materials.

characteristic

Low performance smoke

The insulation and sheath materials of cables used in nuclear power plants must be low smoke, non-toxic, and corrosion-free halogen-free flame-retardant cables, such as thermoplastic flame-retardant halogen-free or cross-linked flame-retardant halogen-free materials, in order to meet special nuclear safety requirements. When a halogen-free cable undergoes a fire, the amount of smoke released during combustion is very low, without toxicity or corrosiveness. Its flame retardant components can effectively exert their flame retardant effect and will not make the cable a channel for flame spread. The main technical characteristics of halogen-free flame-retardant cables include: (1) the total accumulated smoke Dm of cables used in nuclear power plants is less than 150; (2) Non toxic and corrosive, that is, the combustion of the cable does not release HCI and CO; (3) It has flame retardancy, and the flame retardancy of polymers is usually evaluated using the oxygen index (0I) method, with an OI ≥ 28.

Environmental resistance

The materials used for nuclear power plant cables must have environmental resistance, including heat resistance, radiation resistance, and LOCA resistance.

(1) Heat resistance is due to the fact that nuclear power plant cables often work in high-temperature environments, such as high-temperature cables. Therefore, they need to have long-term heat resistance performance, choose polymers that meet the requirements of heat resistance, and ensure that the cable has a service life of more than 40 years.

(2) Radiation resistance (mild environment, harsh environment): When cables used in nuclear power plants are exposed to a large amount of radiation, the insulation and sheath materials become brittle and the mechanical properties deteriorate. Therefore, as insulation and sheath materials for nuclear power plant cables, they must have excellent radiation resistance. Various types of polymers have different radiation resistance properties. People usually add radiation resistant agents to polymers to improve their radiation resistance.

(3) In LOCA resistant nuclear power plants, Loss of coolant accident (LOCA) and High energy line break (HELB) are commonly referred to as LOCA. When a LOCA/HELB occurs, the cable will be subjected to the impact of high-temperature and high-pressure steam, corrosive chemicals, and higher doses of radiation than normal operating conditions. Therefore, nuclear power plant cables should have resistance to LOCA.