Neutron Detector Mineral Insulated Metal Sheathed Cable

Neutron Detector of MI Cable for Nuclear Power Plant is used to measure the core power distribution of the reactor and output the current signal which is proportional to the core neutron flux.

The product consists of a continuous metal sheath, signal core wire, vanadium emitter and mineral powder insulation material. The insulating material between the vanadium emitter and the signal wire and the metal sheath is usually Al₂O₃.

Specific structural dimensions and performance parameters need to be customized or developed according to your needs

Special purpose mineral insulated cable is composed of conductor core, closely compacted mineral insulated powder and metal sheath, which has excellent characteristics of high temperature resistance, radiation resistance, corrosion resistance and high mechanical strength. However, due to the existence of irreducible and extremely fine air gap in the mineral powder insulation layer, it is easy to absorb moisture and reduce its insulation resistance when exposed to the air.

In order to ensure the insulation performance of the cable and avoid damage during use, the following matters shall be noted during storage and use:

1. The cable shall be stored in a dry and sunshade room, and shall be protected from rain, moisture, immersion and corrosion, as well as the damage of the temporary end sealing of the cable.

2. When it is necessary to remove temporary sealing or cut cable, such as making sealing, it shall be carried out in indoor environment with humidity below 30%, and the sealing shall be completed within 20 minutes after cable end cutting or remove temporary sealing.

3. When making cable terminations, the loose mineral insulation powder at the end shall be removed, and the exposed conductor and the outer surface of metal sheath at least 1cm long at the end shall be cleaned with clean cotton-yarn or fine-sand cloth

4. After removal or cutting of temporary cable termination, if the cable cannot be terminated within 20 minutes, it shall be placed in a dry oven or other similar environment with a temperature of not less than 150 ℃ for closed storage to prevent the cable from moisture absorption.

5. After the cable is cut, if it is not used in a short period of time, it shall be sealed temporarily with hot melt adhesive and heat shrinkable sleeve and stored as required.

6. If it is found that the temporary sealing end of the cable is damaged and the insulation is reduced, one of the following two methods can be adopted:

——Remove the damaged temporary sealing end of the cable, and use the blowtorch to dry the damp end until the specified insulation value is reached, and then use the hot melt adhesive and heat shrinkable sleeve to seal the end temporarily;

——Remove the temporary sealing ends at both ends of the cable, and conduct moisture removal treatment in the oven or heat source with the temperature not lower than 200 ℃ until the insulation reaches the specified insulation value, and then use hot melt adhesive and heat shrinkable sleeve to temporarily seal the ends.

7. When welding the cable sheath, ensure the reliable electrical connection between the metal sheath and the grounding wire of the welding machine.

8. During cable installation, in addition to the forced cooling hollow mineral insulated cable, the bending radius of the cable shall meet the following limits:

——Cables with an outer diameter of 5mm or less: the minimum bending radius shall not be less than 3 times the outer diameter of the cable;

——Outer diameter 5mm-10 mm (including 10 mm) cable: the minimum bending radius shall not be less than 4 times the outer diameter of the cable;

——Outer diameter of 10-15 mm (including 15 mm) cable: the minimum bending radius shall not be less than 6 times the outer diameter of the cable;

——Cable with an outer diameter of 15mm and above: the minimum bending radius shall not be less than 10 times of the outer diameter of the cable;

9. The minimum radius of cold bending of forced cooling hollow mineral insulated cable shall not be less than 50 times of cable outer diameter.